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i770 00924 0120–VHBE BELL EDUCATION CENTRE

HANDOUT

A1000 S12FUNCTIONAL DESCRIPTION

Edition : 06

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iiBELL EDUCATION CENTRE 770 00924 0120–VHBE

The Bell Education Centre put in a great effort to give you this document. In case you haveany remarks, do not hesitate to send us your comments.

Our Training Directory describes all training programmes and modules this document (andothers) is used in.

This document was especially written for use during class instruction. The contents of this document is generic. It deals with concepts and principles, rather thanwith the latest releases of and modifications to the product delivered to the customers.

International audiences use this document. It is therefore written in a clear, concise andabove all, consistent language.

iii770 00924 0120–VHBE BELL EDUCATION CENTRE

PREFACE 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. A1000 S12 OVERVIEW 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Introduction 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Exchange structure 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 Hardware 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.2 Software 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.3 Equipment practice 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3 Configurations and applications 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.4 Supplementary Services 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4.1 Centrex 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4.2 Business Communication Group (BCG) 17. . . . . . . . . . . . . . . . . . . .

1.5 Operation, Administration & Maintenance (OA&M) 18. . . . . . . . . . . . . . .

2. A1000 S12 HARDWARE 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 The Digital Switching Network (DSN) 19. . . . . . . . . . . . . . . . . . . . . . . . . .

2.1.1 Introduction 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.2 Digital Switching Element (Multiport) 21. . . . . . . . . . . . . . . . . . . . . . . 2.1.3 Switching in the Multiport 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.4 Network Structure 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.5 Network addresses 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.6 Blocked Paths 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.7 Tunnels 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2 Generic structure of a module 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Terminal Interface 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.2 Processor 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.3 Physical implementation of the Control Element 50. . . . . . . . . . . . . 2.2.4 The On Board Controller (OBC) 55. . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3 Description of the different hardware modules 56. . . . . . . . . . . . . . . . . . . 2.3.1 The Analogue Subscriber Module (ASM) 56. . . . . . . . . . . . . . . . . . . 2.3.2 Digital Trunk Module (DTM) 64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.3 High–performance Common Channel Module (HCCM) 83. . . . . . . 2.3.4 Service Circuit Module (SCM) 84. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.5 Trunk Testing Module (TTM) 95. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.6 Clock & Tone Module (CTM) 99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.7 Digital Integrated Announcement Module (DIAM) 110. . . . . . . . . . . . 2.3.8 Peripheral & Load Module (P&L) 112. . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.9 ISDN Subscriber Module (ISM) 117. . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.10 Mixed Subscriber Module (MSM) 122. . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.11 ISDN Trunk Module (ITM) 122. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.12 The Data Link Module (DLM) 124. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.13 EPM: Extended Peripheral Module 124. . . . . . . . . . . . . . . . . . . . . . . . 2.3.14 ISDN Remote Subscriber Unit (IRSU)

ISDN RSU Interface Module (IRIM) 127. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.4 Remote Terminal Sub Unit (RTSU) 136. . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. A1000 S12 SOFTWARE 143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Functional subsystems 143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3.2 Software concepts 146. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Finite Message Machine (FMM) 146. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Messages 152. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3 System Support Machine (SSM) 157. . . . . . . . . . . . . . . . . . . . . . . . . .

3.3 Communication between processes 159. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Communication within the same CE 161. . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Communication over a virtual path (VP) 162. . . . . . . . . . . . . . . . . . . . 3.3.3 Communication over a user controlled path (UCP) 168. . . . . . . . . . . 3.3.4 Communication with the internal packet protocol (IPP) 171. . . . . . .

3.4 Software modules 174. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 Logical grouping of the Call Handling software into call control planes . . . . . . . .

1743.4.2 Operating System 179. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Database 182. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Device handler FMMs 192. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.5 Signalling system 193. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.6 Call Control 194. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.7 Auxiliary Resources TCE Allocator 194. . . . . . . . . . . . . . . . . . . . . . . . 3.4.8 Analysis of the Called Party Digits 195. . . . . . . . . . . . . . . . . . . . . . . . . 3.4.9 Subscriber analysis 202. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.10 Trunk Search 208. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.11 Device Interworking Data 217. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.12 Private Access Resource Management (PARM) 218. . . . . . . . . . . . . 3.4.13 Physical mapping of the software onto control elements 223. . . . . .

4. A1000 S12 EXCHANGE CONFIGURATION 225. . . . . . . . . . . . . . . . . . . 4.1 Input/Output exchange devices 225. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2 Control Elements 227. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 Control element configurations 227. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 Terminal Control Elements (TCEs) 228. . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3 System Control Elements 229. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4 Auxiliary Control Elements 230. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.3 Software principles and organisation 233. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 Programs and data on mass storage media 234. . . . . . . . . . . . . . . . . 4.3.2 Memory organization 234. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3 CE logical and physical identities 235. . . . . . . . . . . . . . . . . . . . . . . . . .

4.4 J–Rack family 236. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5 Training Exchange (TREX) 240. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.1 Rack alarm gathering 251. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5. CALL HANDLING OVERVIEW 253. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 dtuaPossible accesses to an exchange 253. . . . . . . . . . . . . . . . . . . . . . . .

5.2 Overview of the call types 254. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.3 Call handling blocks 256. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Terminating or Local Call 258. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Transit or Outgoing Call 259. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.3 Hunting to lines/trunks 260. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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5.4 Overview of the call phases 260. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.1 Originating exchange 260. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.2 Incoming exchange 263. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.5 Generic call scenario 264. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.1 Call Setup 264. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.2 Answer 269. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.3 Release (Local Call only) 270. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. CALL HANDLING EXAMPLES 273. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Local call with analogue subscribers 273. . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1.1 Seize A–party 275. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.2 Start scanning for digits / Send dial tone to A–party 281. . . . . . . . . . 6.1.3 Activate call control / Perform A–party analysis 288. . . . . . . . . . . . . . 6.1.4 Receive prefix digits 289. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.5 Perform prefix analysis 291. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.6 Receive remaining digits / Release receiver 293. . . . . . . . . . . . . . . . 6.1.7 Perform B–party analysis / Request DID 296. . . . . . . . . . . . . . . . . . . 6.1.8 Seize B–party / Start ringing phase 298. . . . . . . . . . . . . . . . . . . . . . . . 6.1.9 Activate charging 304. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.10 Pass to stable state 305. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.11 Detect ring trip 306. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.12 Stop charging / Release A–party 307. . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.13 Release B–party 311. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2 Local call with ISDN subscribers 312. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 Example of an ISDN 312. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 Overview of the ISDN protocols 314. . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.3 Layer three: the network layer 315. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.4 Layer two: the data link layer 316. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.5 Layer one: the physical layer 318. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.6 Terms and definitions 319. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.7 Handling of a Q.931 message in S12 321. . . . . . . . . . . . . . . . . . . . . . 6.2.8 Local ISDN call overview 322. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.9 Local ISDN call in detail 325. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.3 Outgoing / incoming call with CCS N7 signalling 330. . . . . . . . . . . . . . . . . 6.3.1 Introduction 330. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2 CCS N7 overview 333. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.3 Outgoing / incoming N7 call overview 339. . . . . . . . . . . . . . . . . . . . . . 6.3.4 Outgoing / incoming N7 call in detail 346. . . . . . . . . . . . . . . . . . . . . . .

6.4 Transit N7 call 354. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.5 Outgoing / incoming call with CAS/R2 signalling 355. . . . . . . . . . . . . . . . . 6.5.1 CAS line signalling 355. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.2 R2 register signalling 359. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.3 Outgoing / incoming R2 call overview 366. . . . . . . . . . . . . . . . . . . . . . 6.5.4 Outgoing / incoming R2 call in detail 368. . . . . . . . . . . . . . . . . . . . . . .

7. FACILITY HANDLING 373. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Overview of some of the supplementary services 373. . . . . . . . . . . . . . . .

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7.2 Facility handling model. 379. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.1 General structure 379. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 Call and Facility Control System (CFCS) architecture 380. . . . . . . .

7.3 Supplementary service data structures. 381. . . . . . . . . . . . . . . . . . . . . . . . 7.3.1 Semi permanent data 381. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2 Dynamic data 383. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.4 Triggers to activate supplementary services. 385. . . . . . . . . . . . . . . . . . . . 7.4.1 Trigger from the Originating profile. 385. . . . . . . . . . . . . . . . . . . . . . . . 7.4.2 Trigger from the Prefix Analysis result. 386. . . . . . . . . . . . . . . . . . . . . 7.4.3 Trigger from the terminating profile. 387. . . . . . . . . . . . . . . . . . . . . . . . 7.4.4 Recall pulse from the subscriber received. 387. . . . . . . . . . . . . . . . . . 7.4.5 Trigger from received signalling events (Event monitoring). 388. . . 7.4.6 Busy/free changes of a subscriber line (Monitor Access). 390. . . . .

7.5 Facility handling examples 393. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.1 Subscriber Control (SC) 393. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2 Call Completion to Busy Subscriber (CCBS) 395. . . . . . . . . . . . . . . . 7.5.3 Malicious Call Identification (MCI) 401. . . . . . . . . . . . . . . . . . . . . . . . .

8. CHARGING 407. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Charging functions 407. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.2 Different ways to charge calls... 408. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Bulk billing 408. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2 Detailed billing 408. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.3 Detailed billing observation 408. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.4 Toll ticketing 409. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.5 Automatic Message Accounting (AMA) 409. . . . . . . . . . . . . . . . . . . . . 8.2.6 Division of revenue (accounting) 409. . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.7 Charging statistics 409. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.8 Limit of credit 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.9 Advice of charge (AOC) 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.10 Facility charging 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.3 Charging methods 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.1 Unit charging 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.2 Continuous charging 411. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.4 Charging analysis 413. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.1 Charging analysis with MMC commands 413. . . . . . . . . . . . . . . . . . . 8.4.2 Charging parameters 413. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.3 Software involved with charging analysis 423. . . . . . . . . . . . . . . . . . .

8.5 Charging generation 425. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.6 Charge scale change–over 426. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.7 Charging collection 427. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.1 Bulk billing collection 427. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.2 Detailed billing collection 428. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.3 Division of revenue collection 431. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8.8 Charging output 433. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.1 Bulk billing output 433. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vii770 00924 0120–VHBE BELL EDUCATION CENTRE

8.8.2 Detailed billing output 434. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.3 Division of revenue output 437. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9. MAINTAINING AN A1000 S12 439. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 System and microprocessor initialization 439. . . . . . . . . . . . . . . . . . . . . . .

9.1.1 CE initialization 439. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2 System initialization 445. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.3 OBC initialization 454. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9.2 Introduction to maintenance 455. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9.3 Hardware and software used in maintenance 455. . . . . . . . . . . . . . . . . . .

9.4 Maintenance concepts 458. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.1 Definitions 458. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Relationship 459. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.3 Security block states and state transitions 463. . . . . . . . . . . . . . . . . . 9.4.4 SBL management on CE Level (SBL=CTLE) 465. . . . . . . . . . . . . . . . 9.4.5 Automatic error handling 467. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.6 Corrective maintenance 471. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.7 Alarm system 472. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.8 Preventive maintenance 478. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.9 Summary report for all scheduled routine tests 480. . . . . . . . . . . . . .

10.OPERATING AN A1000 S12 483. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 IOS overview 483. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.1.1 Introduction 483. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1.2 IOS functions 484. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1.3 Overall structure 486. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.2 Hardware configuration 490. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.3 File–oriented interface 494. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.1 Introduction 494. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.2 Logical file 495. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.3 Logical device 496. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.4 Physical and virtual devices 498. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.4 The MMC interface 499. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.1 Introduction 499. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.2 MMC–dialogue–interface 500. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.3 MMC–monologue–interface 502. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.4 Logging 503. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.5 Exchange administration 504. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11. ADMINISTRATION 507. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction 507. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11.2 Traffic measurements collection and supervision 508. . . . . . . . . . . . . . . . 11.2.1 Measurements based on statistical counters 508. . . . . . . . . . . . . . . . 11.2.2 Call observation 511. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.3 Supervision 513. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11.3 Exchange management 514. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.1 Analogue and ISDN subscriber line administration 514. . . . . . . . . . .

viiiBELL EDUCATION CENTRE770 00924 0120–VHBE

11.3.2 Routing administration 516. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.3 Prefix administration 519. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.4 Charging administration 520. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11.4 Network management 522. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4.1 Destination controls 524. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4.2 Routing controls 528. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4.3 Machine congestion analysis 532. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11.5 Extensions 532. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ��

��

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1770 00924 0120–VHBE BELL EDUCATION CENTRE

PREFACE

Alcatel 1000 System 12 (A1000 S12) offers the main advantage of having fully distributedcontrol. As a consequence, the hardware and software are structured in separate modules,each module interacting with others by means of well defined interfaces. Because of thismodular structure it is possible to study each module separately.

The System Overview was the basis to gather fundamental information about System 12.Only general topics of every domain were treated.

The main objective of the ’Functional Description’ is not only to give the reader moreinformation about every module (hardware and software), but first of all to link all thesemodules together. These links are explained by describing a local and an outgoingtelephone call in more detail.

The intention is that after this course, a trainee understands exactly which hardware andsoftware parts are involved in a telephone call. From each part he will posses the functionalknowledge.

It is certainly not the purpose of this course that detailed information is given by the trainer.Detailed material is explained in separate courses, that follow the Functional Description. Atcertain points in the text, references to the detailed courses are made.

To arrive to those objectives, a good knowledge and understanding of the following items isnecessary before getting started :

� General knowledge of digital telephony and data communication

� System Overview: 770 00435 6560–VHBE

http://dms.bel.alcatel.be/secure/cgi-bin/osform/dms?osform_template=calldoc.oft&act=HLINK&code=_770/_00/_435/_6560/_vhbe__.pl

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2BELL EDUCATION CENTRE 770 00924 0120–VHBE

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1. A1000 S12 OVERVIEW

1.1 Introduction

During the first years of this century the role of the telephone industry was that of providing aworldwide network dedicated, above all, to voice communication. For that purpose,Analogue and mechanical nodes and transmission means were developed.

However, the appearance of new technologies, such as the computer and the capacity forthe large scale integration of circuits, has led to great changes. These changes are, on theone hand, the automation of the telephone networks through the incorporation of storedprogram switching nodes and digital transmission mechanisms; and on the other, theemergence of needs for non–voice communication: data, images, etc., which in turn impactsthe design and development of communication networks.

Therefore, at present a series of alternative networks are being created. These newnetworks must by means of international standards and strategies, in order to create a singleintegrated service network. In this context A1000 S12 presents itself as a switching systemthat is applicable to almost all existing networks and adaptable to future needs and services.

A1000 S12 is designed mainly for use in the Public Switched Telephone Network (PSTN),providing access to Analogue subscribers, ISDN, mobiles, private branch exchanges,remote units, etc. Furthermore, the system can be incorporated into the Packet SwitchingNetwork (PSN), Broadband ISDN, Intelligent Networks, Telecommunication ManagementNetwork, Alcatel MAN, etc.

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Figure 1 : A1000 S12 environment

Network Service Centre A1000 S12

Analogue Subscriber ISDN Subscriber

Broad Band

Network

Cellular

Network

Private Exchange

PublicSwitched

TelephoneNetwork

Packet

Switching

Network

Remote SubscriberUnit (RSU)

(PBX)

(NSC)

From a user point of view, access to A1000 S12 is provided by a set of I/O interfaces inorder to use its services and control its operation.

Telephonic interfaces allow telecommunication network users to connect each other toexchange information (voice and data). The most basic interface is the two wireloop,although there are also more powerful ways of access by using high quality carrier systems.Thus, digital exchanges are connected to each other by means of multiplexed lines (digitaltrunks). This means that several conversations are transmitted by just one physical cable. Inaddition, data links are used to gain access to O&M remote centres or data processingcentres.

The simplest known interface is obviously the subscriber loop. This subscriber loop is madeup of a couple of wires used for full duplex transmission. It goes without saying that the linefeatures allow the transmission of Analogue signals within the band from 300 to 3400 Hz.Subscribers’ telephone sets employ either decadic or multifrequency dialling. This sort of lineis used for voice communication as well as for data communication by means of modems.

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Figure 2 : Analogue subscribers

Analogue telephone set

Modem

ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ

Power

freq.

A1000 S12

300 3400

Another interface, defined according to the same type of physical connection, is the set ofbasic accesses to ISDN. As we already know, sophisticated digital transmission andreception equipments can use a couple of wires for the emission of two 64 Kb/s channels(voice or data) and additionally one 16 Kb/s channel used for signalling.

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Figure 3 : ISDN subscribersISDN telephone set

A1000 S12

NT

B1 B2 DPC

B1: 64 Kbps

B2: 64 Kbps

D : 16 Kbps

An upper level is the access to the telephonic network from Private Branch Exchanges.These PBXs are connected to the host exchange through different types of interfaces.

The most basic interface consists of a set of lines (couples of wires) in charge of distributingthe outgoing calls, with the host exchange handling the incoming calls directed to thesubscriber’s line. Another method is to use high–quality lines (PCM Links). This allowsadvanced control access by using a signalling channel (usually #16). Finally, PBXs can beconnected to ISDN exchanges by means of the PRA interface (Primary Rate Access) whosestructure is similar to PCM but which uses a different signalling protocol.

In order to provide global telephone service, all the telephone network exchanges areconnected to each other by means of trunks. Usually digital, these trunks forward theinformation through 2048 Kb/s PCM frames supported on coaxial cables, radiolinks, oroptical fiber.

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Figure 4 : ISDN PABX

ISDN telephone set

A1000 S12

NT

PCB1: 64 Kbps

B2: 64 Kbps

D : 16 Kbps

ISDN PABX

30 B D

Coaxial Cable

B1 B2 D

Finally, let us consider the access to network management centres. The most commonlyused systems are the N7 signalling and X.25 data protocols. The O&M and Taxation users(OMUP and TAXUP respectively) are usually connected to the Network Service Centre(NSC) through the N7 signalling network. The X.25 protocol is used as link between the

exchange and some data processing centres (EDPC).

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Figure 5 : Exchange interconnection

A1000 S12

30 +1+1

PCM format

Coaxial Cable

Remote ExchangeRemote Exchange

Coaxial Cable

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Figure 6 : Management centres

X.25

X.25

N7

X.25PSN

NETWORKSERVICECENTRE

ELECTRONICDATA PROCESSINGCENTRE

NETWORK

X.25

N7N7

A1000 S12

1.2 Exchange structure

The A1000 S12 exchanges are characterized by two essential properties: digital technologyand distributed control.

First, A1000 S12 is said to use digital technology because its control and functions areperformed by programs that are executed on microprocessors, and the information internalhandling (switching and transmission) is carried out by fully digital techniques. Thesefeatures make the system capable of handling any piece of information, whatever its nature(speech, data, text, etc.), as long as it is digitized, thus ensuring a better quality thanks to theactual advantages of digital transmission and the absence of moving or mechanical parts.

Secondly distributed control means that the functions carried out by the system, from aglobal point of view, are divided into sets of tasks which are grouped in a homogeneous wayand assigned to specific and specialized control elements. This idea allows to obtain of avery reliable system for failures of control elements do not entail a meaningful impact on thesystem. Furthermore, the way in which the different functions are organized allows new onesto be added without having to redesign the system and, therefore, permits the easyadaptation to new needs and services as they arise in the market.

The implementation of a system with these characteristics is achieved with the design of aninternal digital switching network that interconnects the different system modules to transmit

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internal control information as well as user data over the same paths. This internal networkcan be easily extended by the addition of new modules. Furthermore, the network switchingcontrol is of the gradual type (non–centralized) which simplifies its use. Another factorcontributing to the reliability of the System is that the network allows to link two modulesthrough multiple paths in order to ensure minimum blocking probability.

Another significant advantage is the use of customized integrated circuits (CLSI – CustomLarge Scale Integration –), which allows the optimization of the number of functionsperformed by each printed circuit board, making possible the building of extremely compactand reduced equipment.

1.2.1 Hardware

The A1000 S12 functional structure is remarkably simple; it consists of an internal switchingnetwork to which a variety of terminal modules are connected according to the size of theexchange and the services and facilities offered.

The A1000 S12 functional diagram has, therefore, a spider look (’Spider Diagram’) wherethe nucleus is the internal switching network and the extremities are the modules. Thesemodules are connected to the network through transmission PCM links modified for theiradaptation to the functions required by the system interior.

The internal switching network (DSN –Digital Switching Network–) is formed by a set ofbasic switching elements arranged under a folded topology. Given that the DSN’s number ofstages and planes can be increased with great easiness, there are two potential ways ofexpansion: the number of inlets (terminals connected), and the possibility of alternativepaths (traffic flow capacity).

On the other hand, all the modules are connected to the network through two modified PCMlinks presenting a single input and output protocol irrespective of the module. All the

modules contain a common part called Control Element or CE , composed of amicroprocessor and its memory, and a standard interface circuit towards the switchingnetwork. These CEs are classified into two groups: Terminal Control Elements or TCEs, and

Auxiliary Control Elements or ACEs .

The TCEs are those control elements that are connected to a cluster or circuitry associatedwith the specific module functions, for example line circuits, trunk circuits, etc.. The interfacetowards the cluster circuits is also standard. However, there are other control elementswhich are exclusively dedicated to performing support functions for the TCEs. They carry outspecific tasks such as error handling, prefix analysis, local subscriber identification, etc.,without including any cluster or circuitry aside from the actual CE. These control elementsare called ACEs.

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Figure 7 : System diagram

ACE TCEAnalogueCIRCUITS

TCE

TCETCE

TCE

TCE

SUBSCRIBER MODULESTRUNK MODULES

SERVICE MODULES

CLOCK & TONE MODULES

PERIPHERAL &LOAD MODULES

C & TCIRCUITS

P & LCIRCUITS

SERVICECIRCUITS

TRUNKCIRCUITS

DigitalSwitchingNetwork

AUXILIARY CONTROL

ELEMENTS

DIGITALSIGNALLING

CIRCUITS

DIGITAL SIGNALLINGHANDLING MODULES

Some of the major A1000 S12 modules are briefly described below:

� Analogue Subscriber Module:

Composed of a control element and a set of line circuits that provide access toAnalogue subscribers. The different types of Analogue subscribers (regular, publiccoinbox, priority class, etc.) are all supported through the same type of line circuit.

There are other similar modules for access to ISDN subscribers, mobile subscribers,etc.

� Digital Trunk Module:

Consists of a CE and the digital trunk circuits required to provide access to externalsystems (telephone exchanges, private automatic branch exchanges, remotesubscriber units, etc.) through a standard PCM link. The same piece of equipment isable to handle different signalling types (MF or digital) that can be supported byspecialized signalling modules (Services Circuit Modules and Digital SignallingHandling Modules).

� Peripheral & Load Module:

This module performs functions to access pieces of equipment such as peripherals

(Man Machine Communication terminals, printers, tapes, disks, etc.) and panelsand alarm lamps.

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� Clock & Tone Module:

Provides the system synchronization signal and generates the necessary telephonictones.

� ACE :

They perform auxiliary functions depending on the associated set of programs anddata. These programs define the name given to the ACEs.

These and other modules will be described in detail later in this document.

The singular structure described above allows the original design to be maintained for thewhole range of A1000 S12 applications.

1.2.2 Software

The software is organized under the support of an operating system and a data base thatare specific to the system and over which a set of application programs or software modulesare arranged.

The operating system is made up of a series of software functions that allow for themanagement of all the system resources (CPU time scheduling, memory management,communication through the network, etc.). This software subsystem is distributed over thesystem microprocessors.

The data base consists of the information it contains in the form of tables or relations(relational data base), and the programs to manage and access the data contained. Thesetwo elements, the data and the programs, are also distributed over the system, yet all theinformation can be accessed by any microprocessor.

The programs in charge of performing the actual system functions, such as signalling,switching, charging, etc., are designed as independent modules. These modules reside inthe control element or elements where they must carry out their tasks. The exchange of databetween different software modules, whether they reside in the same CE or not, iscoordinated making use of the services provided by the operating system and carried out bymeans of data units called Messages .

1.2.3 Equipment practice

The A1000 S12 digital exchanges are extremely compact and can be installed in regularcommercial buildings.

As regards the equipment’s physical appearance, the System consists of printed circuitassemblies, panels, subframes (also called ’shelves’) and racks.

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As mentioned before, the use of the customized circuit manufacturing technique (CLSI)allows the integration of a great number of functions in a single printed board. Thesesmall–sized boards are inserted into slots, inside subframes laid in racks, which areaccessible from the front as well as from the back. These racks are arranged in rows thatappropriately interconnected form the exchange floor over a small area.

Each module is composed of one or more PBAs, which may be equipped in differentlocations of several racks. This means that the rack equipment layout is variable.

Furthermore a set of DC/DC converters are provided to supply different voltages to thecircuits (5V, 12V,...)

Figure 8 : A1000 S12 Exchange floor

EXCHANGE FLOOR

SYSTEM 12

RACK

PBA

SUBRACK

ROW

1.3 Configurations and applications

The A1000 S12 modular structure accommodates a wide range of different configurationsusing the same basic elements and similar equipment structures.

All possible configurations, from small remote units to large local exchanges, are covered.Furthermore, the system can be set to offer the most advanced user facilities whatever theconfiguration.

A brief list of the A1000 S12 product range is outlined on the following page:

� Local, transit (toll) and combined exchangesFrom 512 to 256 000 linesUp to 60 000 trunks

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� International exchanges

� Small capacity exchanges:SSA (Small Stand Alone)From 256 to 3 840 lines VSSA (Very SSA)From 16 to 768 lines.

� Remote applicationsRemote Subscriber UnitsUp to 976 Analogue lines

� Other configurations Network Service Centre SSP in intelligent networks

1.4 Supplementary Services

From a subscriber point of view, A1000 S12 offers a wide range of supplementary services.Some of these supplementary telephone services, such as the following ones, are commonto Analogue and ISDN subscribers:

� Fixed Destination call:

The exchange provides a preprogrammed number without digits send.

� Abbreviated dialing:

Using a short number the user can establish calls to public subscribers.

� Do not disturb:

If active, the exchange considers the user as being busy, and every terminating call tothe user is released.

� Call forwarding on no reply:

Calls to the user are forwarded only on no reply after a time–out.

� Completion of calls to busy subscriber:

The exchange manages the calls to the user holding the incoming call until theterminating subscriber is free.

� Malicious call identification

Information about terminating calls to the user is stored in case a defined signal isincoming from the called subscriber.

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� etc.

Other facilities, as those outlined below, are exclusively for ISDN subscribers:

� Advise of charge:

The user is informed about charging throughout the call duration or/and at the end ofthe call. The information is shown on the display of the telephone set.

� User–to–user signalling:

ISDN users are able to send their own information through the ISDN using theparticular features of the N7 signalling system.

� etc.

Also, we can mention here some services like Centrex ., Wide Area Centrex (WAC), and

Business Communication Group (BCG).

1.4.1 Centrex

First of all, Centrex is an implementation of a private telecommunication networkexchange that is not located on the premises of the private network operator but which ispart of a public local exchange. The users of a Centrex have the impression of beingconnected to one homogeneous private telecommunication network, which is invisible tothem. The Centrex service is able to provide supplementary services inside the CentrexGroup. However, a Centrex subscribers must be connected to the same local exchange.

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Figure 9 : Centrex Structure

A1000 S12

CENTREX

Subscriber 1

Subscriber N

Centrex user 1

Centrex user M

PBX 1

PBX P

The Wide Area Centrex service improves the basic Centrex to support extensions connectedto different exchanges. The main limitation of WAC is that it has a private numbering planwhich is completely associated with the public numbering plan.

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Figure 10 : Wide Area Centrex

EXCH A

EXCH B

EXCH C

Centrex A subscribers

Centrex C subscribers

Centrex B subscribers

1.4.2 Business Communication Group (BCG)

To solve the above problems, A1000 S12 supports also the Business Communication Group

service. Business Communication is a service that allows business user belonging todifferent exchanges to have a virtual private telecommunication network. ISDN andAnalogue subscribers belonging to Centrex, and private exchanges, can be connected bythis service. Using a private numbering plan, BC users establish calls for voice or datapurposes in the Business Communication Group. Of course, using the public numberingplan, users can reach any subscriber outside the group. This private numbering plan canhave a different structure compared to the public numbering plan.

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Figure 11 : Business Communication Group

EXCH C

Centrex A subscribers

Centrex C subscribers

Centrex B subscribers

EXCH B

EXCH A

PBX

PBX

PBX

PBX

1.5 Operation, Administration & Maintenance (OA&M)

The administration of the A1000 S12 is made easier with the creation of a powerfulman–machine communication system. This communication mechanism supplies theoperator with simple and easy access to all the information related to subscribers, trunks,etc., and, of course, provides all the necessary output messages regarding operatingtroubles or other events that should be notified. The only requirements for the use of thissystem are a series of input–output devices (specific VDU, PC with emulator, printers, etc.)that permit the introduction of action–to–take orders in the form of operation commands, andthe output of messages in the form of text lists either on screen or on the printer.

All the commands that can be executed by the system are arranged in different specializedareas related to subscribers, trunks, charging, etc.

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2. A1000 S12 HARDWARE

2.1 The Digital Switching Network (DSN)

2.1.1 Introduction

The key element in the distributed control possible is the Digital Switching Network. Thisnetwork is a device that carries out space–time switching, i.e., it transfers the contents of anincoming PCM channel to another channel time of a different PCM link .

Figure 12 : Space–time switching

LINK 1

LINK 2

LINK 8 LINK 8

LINK 2

LINK 1

CHANNEL 12

CHANNEL 5

The network is used to switch PCM channels that carry speech samples from the terminalcircuits as well as messages between control elements.

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Figure 13 : Communication between processors

SWITCH

SWITCH

SWITCH

TCE

TCETCE

TCE

NETWORK

ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ

CONTROLDATA

CONTROLDATA

SPEECHSAMPLES

The network presents a folded structure, that is, all the modules are connected to the sameside of the network and the procedure used to access a module from any other module isalways the same irrespective of the modules involved.

The channels supporting every communication progress through the network up to areflection point before they reach their destination.

This structure allows the use of the same basic design for all applications and facilitatesfuture extensions.

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Figure 14 : Communication progress through the network

CH Z

CH X

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

SOURCE

DESTINATION

REFLECTION

POINT

2.1.2 Digital Switching Element (Multiport)

The network is made up of a series of identical units called Digital Switching Elements orMultiports. The Multiports are interconnected by 32–channel PCM links.

The multiport has the ability to carry out space–time switching between the channels of 16incoming PCM links and those of 16 outgoing PCM links. Each incoming PCM link ends atone of the 16 receiver ports in the multiport, and each outgoing PCM link starts at one of the16 transmitter ports.

Physically, the multiport is made up of 1 LSI mounted onto a printed circuit board. This LSIcontains 16 receiver and 16 transmitter ports, and is called SWEL.

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Figure 15 : Multiport structure

0

7

8

15

SWEL..

.

.

communicationbus

ports

line adaptation (Amplifiers)

PCM link

To facilitate the representation of the network, a multiport is depicted with the portsnumbered 0 to 7 on its left and those from 8 to 15 on its right, without implying any functionalchange. Ports 8 to 11 are named ’Low Ports’, and ports 12 to 15 ’High Ports’.

Figure 16 : Multiport representation

0

7

8

15

1

2

3

4

5

6

9

10

11

12

13

14

ports

low numberedports

high numbered

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2.1.3 Switching in the Multiport

The content of each channel is stored, upon arrival, in a memory when it arrives. At theappropriate moment it is read to be transmitted towards the correct destination. In this waythe switching network has progressive control.

The first two of the 16 bits in each channel are the protocol bits. If a channel is not to beswitched, the protocol is 00 (CLEAR); on the other hand, if switching is to be initiatedthrough a channel, these two bits is 01: SELECT command. The remaining bits are used fordifferent purposes.

There are several types of SELECT command. The first is called “SELECT Fixed Port, FixedChannel”. Here, the remaining bits indicate the outgoing port and the outgoing channel. Thisdata relating the input with the output is stored in a special memory. Once the SELECT hasappeared, the switching step has already bee carried out through the storage in the memory,using a common bus mainly composed of: four destination port number lines, fivedestination channel number lines, and sixteen data lines.

The figure shows a multiport switching scheme. The channel X content is saved in an inputmemory. At the time of its creation, the stored protocol is compared against the previouschannel state. If the state is IDLE and the protocol is clear, nothing happens and the stateremains the same. If the state is IDLE, but the protocol is SELECT, the saved channel andport destination identities are stored in the state memory, and the channel state changes toBUSY.

On the other hand, if the channel is already BUSY, and the protocol different from CLEAR,the saved channel content is sent to the addressed transmitter to be stored there in itsoutput memory (into the word addressed by the destination channel identity). To do this, thelines of the common bus are used. The channel state remains BUSY.

The arrival of two consecutive CLEAR idles the channel state.

Protocol overview:

� 00 : IDLE protocol

� 01 : SELECT protocol

� 10 : ESCAPE protocol

� 11 : SPATA protocol

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Figure 17 : Multiport switching

0

1

2

31

0

1

2

31

INPUT

MEMORYSTATE

MEMORY

0

1

2

31

ÌÌÌÌ

STATEDEST.PORT

DEST.CHANN.

BUS

4

5

16

DATA

DEST.CHANN.

DEST.

PORT

ADDRESS

VERIFYIDENTITY

CH X

CH Y

RECEIVE PORT

TRANSMIT PORT

OUTPUT MEMORY

The speech samples representing analogue signals are bytes that are sent as successivecontents of the same channel. The messages between microprocessors are transmitted asbytes (in some cases 12 bits are used), and sent in the same way. The following consecutivecontents of the same channel will come with a protocol 11 (SPATA) if they are speechsamples, or 10 (ESCAPE) if they are data (message between Ps).

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Figure 18 : Communication between processors

C X C X

C Y C Y

C Z C Z

P

MULTIPORT

MULTIPORTTCE

TCEMEMORY

MEMORY

10

8 BITS

ESCAPE

ÌÌÌÌÌÌÌÌÏÏÏÏ

16 BITS

MULTIPORT

MULTIPORTTCE

TCEC Z

11

8 BITS

SPATA

ÌÌÌÌÌÌÌÌ

D / A

C XA / D C Y

C I C X

MESSAGE TRANSMISION

SPEECH TRANSMISSION

µ

Pµ

Pµ

Pµ

However, another possibility is the arrival of other SELECTs that are addressed to multiportslocated deeper in the network. These SELECTs will be handled as SPATA or ESCAPE. Themultiport will handle all of them the same way, driving the channel contents through theoutgoing channel pointed out in the memory. The situation will continue as described until itis “cleared” with the arrival of two consecutive CLEAR (00) protocols which will release theassociation between the incoming and the outgoing channels.

The selection indicating the output port and channel is too strict and for this reason othertypes of SELECT commands are used more often. These other SELECTs may indicate onlythe outgoing port, allowing the actual transmitter to choose a channel from those it has free.This SELECT command is called “SELECT Fixed Port Any channel”. In the most extreme case, neither the port nor the channel is indicated. For this latter case,the receiver has stored in its memory the identity of the ports that have at least one freechannel. When one of these SELECT types is used, the transmit port is requested to providethe identity of the channel that will be used.

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Figure 19 : Port memory with free transmit port channels

RECEIVE PORT TRANS. PORT 8

01

2

31

01

2

31

INPUTMEMORY

STATEMEMORY

LOGIC

10 8 15

PORTS WITH FREE CHANNELS

1 TRANS. PORT 15

CHOOSE ONE

CHANNEL

SELECTEDCHANNEL

EVERY TRANSM.

PORT WRITES

PERIODICALLY INTO

THIS MEMORY

1 = AT LEAST ONE FREE CHANNEL0 = NO FREE CHANNELS

This SELECT command is called “SELECT Any port, any channel”. This command choosesany channel of a port in the set 8–to–15. This allows the progression of the incomingchannel deeper through the network (right side on the drawings). There are other SELECTsthat are used for a very particular case of progression through the network which will beseen later. These commands are the SELECT “Any Low port, any channel” (any channel ofthe port 8, 9, 10 or 11), and SELECT “Port P or P+4, any channel”.

In order to allow for the proper operation of everything seen thus far, every incoming PCM

link contains an alignment pattern in all its zero channels to allow the recognition of thestart of each frame.

The transmitter ports emit this pattern through their zero channels.

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Figure 20 : Patterns emitted by the transmit port

0

310 0

0Rx

Tx Rx

Tx

Multiport A Multiport B

Pattern Alignement

p q

2.1.4 Network Structure

The switching network is made up of a set of multiports that are connected in such a waythat there is full accessibility between the terminals and the probability of internal blocking isminimal.

First, we will study the connection of the modules to the network and then, theinterconnection of the multiports.

a. Connection of the modules to the network

The modules are connected through a pair of multiports called Access Switches (AS).Each PCM link outgoing from the TI is connected to the first port in each AS.Depending on the traffic carried by the modules, eight or four of them are connected to

two multiports making up a structure called TSU (Terminal Sub–Unit).

In this example, if the modules are subscriber modules, a TSU can contain a maximumof 1024 subscriber lines.

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Figure 21 : TSU structure for subscriber modules

MODULE 0

MODULE 1

MODULE 7

ACCESSSWITCH

ACCESSSWITCH

8

9

10

11

12

13

14

15

8

9

10

11

12

13

14

15

TO GROUPSWITCHES

TO GROUPSWITCHES

0

1

7

0

1

7

In order to allow the interconnection of modules belonging to different TSUs, ports 8 ofthe eight access switches are linked together, using the first eight ports (0–7) of amultiport as shown in the figure below. This multiport is called Group Switch (GS).This

structure is called TU (Terminal Unit).

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Figure 22 : TU structure

TI

ÏÏÏÏÏÏÏÏÏÏÏÏ

7

ÑÑÑÑÑÑÑÑÑÑÑÑ

6

ÓÓÓÓÓÓÓÓÓÓÓÓ

5

ÌÌÌÌÌÌÌÌÌÌÌÌ

4


3

ÑÑÑÑÑÑÑÑÑÑÑÑ

2

ÓÓÓÓÓÓÓÓÓ

1


0ÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌÌ

ÏÏÏÏÏ

ÏÏÏÏÏ

TI

TI

TI

4th TSU

1st TSU

GS

8

8

8

8

8

8

8

8

01

234567

ONLY ONE MULTIPORT

IN FIRST STAGE

Thus, four TSUs form a Terminal Unit (TU). The eight access switches are numberedfrom 0 to 7 and connected to the same port number in the GS. AS 0 and 4 belong tothe first TSU, 1 and 5 to the second one, 2 and 6 to the third one and, 3 and 7 to thefourth one.

b. Interconnection of Group Switches

If there is more than one TU, it will be necessary to interconnect them. This is achievedwith multiports in a second network stage.

Up to eight TUs are connected under a structure named SECTION . A Section isestablished by connecting the eight GS in the first stage with another eight multiports inthe second stage, using a multipath–topology.

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Figure 23 : Section structure

00

1 1

7 7

0

0

0 0

0

0

1

1

1

7

7

7 7

7

7

8

8

8 8

8

89

9

9

15

15

15 15

15

15

FROM 8thTU

FROM 2ndTU

FROM 1stTU

1st STAGE 2nd STAGE

SECTION

The algorithm that defines the connection between the 1st and 2nd stages is asfollows:

1st stage multiport no. = 2nd stage port no.1st stage port no. – 8 = 2nd stage multiport no.

If there is more than one section, up to 16, it will be necessary to interconnect all ofthem through a third stage. This third stage must be the last stage, thus all ports areoriented to the sections. The third stage is made up of groups. Each group is formed byeight multiports, each of them connected to all sections via one PCM link.

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Figure 24 : Network structure

00

7 7

0

0 0

0

7

7 7

7

8

8 8

8

15

15 15

15

SECTION 15

7

6

5

4

3

2

1

0

TI 0

8

8

8

8

8

8

8

8

TI 7

00

7 7

0

0 0

0

7

7 7

7

8

8 8

8

15

15 15

15

1st STAGE 2nd STAGE

SECTION 0

ACCESS

SWITCHES

0

70

0

15

15

GROUP 0

3rd STAGE

0

7

0

0

15

15

GROUP 7

The interconnection of the 2nd and 3rd stages is defined by the following equations:

2nd stage port no. – 8 = 3rd stage group no. 2nd stage multiport no. = 3rd stage multiport no.2nd stage section no. = 3rd stage port no.

Although one group interconnects all the sections, a maximum of eight groups may beimplemented in order to increase the number of possible paths and minimise theinternal blocking.

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The set of sections and groups is called PLANE . As mentioned before, the accessswitches of each TU are connected to the plane through port 8. If, due to traffic needs,more paths must be provided, up to three more planes can be connected to ports 9, 10and 11 of the access switches (at least two planes are equipped). Ports 12 to 15 areused to connect the ACEs (ACEs are also connected to ports 4 to 7 for low trafficTSUs), the Clock & Tone modules and the Peripheral and Load modules.

Figure 25 : Network structure with four planes

PLANE 4

PLANE 3

PLANE 2

0

7

0 0 0

0 0

7 7 7

7 7

80 0 0

7 7

8

15 15 15

PLANE 1

SECTION 0 GROUP 0

SECTION 15 GROUP 7

STAGE 1 STAGE 2 STAGE 3

ACCESS

SWITCHES

8

9

10

11

TERMINAL

INTERFACE

The exchange sizing up rules define the number of group switches per plane necessaryfor a given number of terminals, while the value of the expected traffic flow gives thenumber of planes, bearing in mind that the equipment is identical in all planes and thattwo planes are always equipped for security purposes.

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Figure 26 : Network growth

NUMBER OFTERMINALS

TRAFFIC 1 STAGE 2 STAGES 3 STAGES

2 PLANES

3 PLANES

4 PLANES

2.1.5 Network addresses

A network path will be established with consecutive SELECT commands that a controlelement will emit through one of the channels that link it to the access switches. This way,the path will be established gradually, advancing towards the interior of the network up to thereflection point in order to reach the destination module.

This path will be the shortest possible one, in such a way that, for modules of the same TSU,the reflection will take place at the access switch, for modules of the same TU at the 1ststage, for modules of the same section at the 2nd stage and, at the 3rd stage when theybelong to different sections. This means that the number of SELECT commands used will be1, 3, 5 and 7 respectively.

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The following figure shows an example of a path established between the CEs A and B, witha single SELECT command, that is, the reflection point is at the access switch. Thecommand used is the following one (on this figure and on the following ones, only the firstplane is represented):

Step (1) – SELECT PORT 4, ANY CHANNEL.

Figure 27 : Reflection at the Access Switch

(1)TI 0

CE A

40

80

1st STAGE

0

40

8

15

8

8

15

7 7

0

7

8

15

7

0

15

0

0

15

GROUP 0SECTION 0

SECTION 15

0

0

15

0

0

7

8

15

0

7

8

157

7

8

15

GROUP 7

0

15

0

15

0

15

2

TI 3

CE B

44

0

2nd STAGE

0

7

8

15

0

3rd STAGE

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The following figure shows a path set with 3 SELECT commands, that is, the reflection pointis located in the first stage. The commands used are:

(1) SELECT LOW PORT, ANY CHANNEL(2) SELECT PORT 2/2+4, ANY CHANNEL(3) SELECT PORT 2, ANY CHANNEL

Figure 28 : Reflection at the first stage

00

7 7

1 0

0

5 7

7

8

8 8

8

15

15 15

15

SECTION 15

0

7 7

0

0

7

7

8

8 8

8

15

15 15

15

1st STAGE

2nd STAGE

SECTION 0

0

7

0

0

15

15

GROUP 0

3rd STAGE

0

7

0

0

15

15

GROUP 7

0

CE A

CE B

TI 0

TI 2

(1) (2)

(3)

4

2

6

00

0

2

2

8

8

8

8

0246

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The following figure shows a path established with 7 SELECT commands, that is, thereflection point is located at the third stage. The commands used are:

(1) SELECT LOW PORT, ANY CHANNEL.(2) SELECT ANY PORT, ANY CHANNEL(3) SELECT ANY PORT, ANY CHANNEL(4) SELECT PORT 15, ANY CHANNEL(5) SELECT PORT 7, ANY CHANNEL.(6) SELECT PORT 1/1+4, ANY CHANNEL(7) SELECT PORT 2, ANY CHANNEL

Figure 29 : Reflection at the third stage

00

7 71 0

0

5 7

7

8

8 8

8

15

15 15

15

SECTION 15

00

7 7

0

6

7

7

8

8

8

1515

15

1st STAGE 2nd STAGE

SECTION 0

0

70

0

15

15

GROUP 0

3rd STAGE

0

7

0

0

15

15

GROUP 7

20

6

12 8

5

2 8

CE A

CE B

TI 0

TI 2

(7)

(6)

(5)

(4)

(1) (2)

(3)

8

0 8

2

15

0 8

In order to be able to connect two modules through a path, it is necessary that each moduleis unequivocally defined. This is achieved with the coordinates of network addresses,indicated with the codes ZYXW or DCBA :

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Z: Indicates the section number (0–15).Y: 1st stage multiport number to which its TU is connected (0–7).X: Lowest access switch number to which its TSU is connected (0–3).W: Control element number within its TSU (0–7 and 12–15).

Another view of coordinates is related in the following figure:

Figure 30 : Meaning of the coordinates

00

7 7

5

7

8 8

8

15 15

15

SECTION 15

15

15

15

GROUP 7

1

2 8

5

8CE B

TI 2

ACCESS

SWITCH

COORDINATE W COORDINATE ZCOORDINATE YCOORDINATE X

Input ports toAccess Switch

Input ports to1st Stage

Input ports to2nd Stage

Input ports to3rd Stage

2

1

7 15

2.1.6 Blocked Paths

As we have seen, the path establishment process is progressive through the network and, toa large extent, random since the exact path that is going to be selected is not knownbeforehand.

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When a SELECT command is executed in a multiport, the transmitter port involved sends anacknowledgement signal to the receiver, provided that the switching can be carried out.Thus, when executing the SELECT “port P, any channel”, if the transmitter port P has no freechannels it will not send the acknowledgement signal, whereby the incoming channel passesto the “not acknowledged” state (NACK) , which is memorized at the receiver.

The switching steps that have been established up to the NACK point are then no longer ofany use and the path must be released. For this, the processor that originated the SELECTcommand is notified making use of channel 16 of the PCM links parallel to those alongwhich the path was thus far established.

Figure 31 : NACK sending through the network

4

7

16

16

TRANSMISSION NACK BACKWARDS

T5 WITH NOFREE CHANNELS

0 8

1

6

TI

SWITCHINGNOT POSSIBLE

1 2

3

4

6

5

Pµ

(1), (2), (3): The path is set up to the first stage. At this stage switching is not pos-sible.

(4): Using backward channel 16 the input channel identity (i.e. 4) is sentback towards the first stage.

(5): The multiport at this first stage sends back the identity of the inputchannel with in channel 16, using the connection related data.

(6): The microprocessor reads this identity and is able to make another at-tempt.

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2.1.7 Tunnels

When a loss of sync occurs at a pair of ports or in the event of a hardware failure, alarminformation is transmitted through channel 0 towards a microprocessor. The arrival of thealarm is marked by changing the channel 0 protocol from CLEAR to SPATA.

Since this information travels through channel 0 and this channel is not switched usingSELECT commands as for the other channels, switching is performed through presethardware switches at every multiport in such a way that the HIGH and LOW ports are linkedtogether. This association is named Tunnel, meaning that is, whatever reaches receiver portP at channel 0 time, leaves through transmitter port P+8 also at channel 0 time; andwhatever arrives at receiver port P+8 leaves through transmitter port P. This way, in a totallyequipped network, the alarm information will reach two microprocessors. In thesemicroprocessors, when channel 0 with SPATA protocol arrives, the channel 0 content isstored in a specified position of the CE RAM, where the microprocessor can read it.

In the case of a network that is only partially equipped, the alarm may reach only one

microprocessor. If this is the case, the “tunnel” is called cave . However, in some cases ofpartial equipment the alarm may not reach any microprocessor; therefore, it will benecessary to implement enough HW jumpers or cross–links for these paths to be at leastcaves so that the alarms can reach at least one microprocessor.

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Figure 32 : Alarm Information reaching the processors

0 8

156 14

16

ALARM

CONTROLELEMENT

SYNCHRONISATION

LOST IN RECEPTION

ALARM–SYNCHRONISATION LOST

–POINTER: ORIGIN OF THE ALARM

7

ALARM ALARM

CH 0 CH 0

CH 0

CH 0

ALIGN. PATTERNCHANNEL ZERO

11

SPATA

Pµ

0 8

CONTROL

ELEMENT

CH 0 CH 0

Pµ

102

0

8

91CH 0

CH 0

2.2 Generic structure of a module

An A1000 S12 exchange is made up of a set of functional modules linked to each otherthrough the digital switching network. Each module is formed by a series of circuits thatperform similar functions, whether of a telephonic or non–telephonic type.

Generally, all the modules have the structure shown in the following figure:

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Figure 33 : Module structure

TERMINAL

INTERFACE

CONTROL ELEMENT

MODULE

CIRCUITS

PROCESSOR&

MEMORY

Two basic parts can be distinguished in the figure: the specific module circuitry which is

specific to each particular case, and the Control Element (CE) . which is common to allsystem modules. The latter in turn is formed by a microprocessor with its main memory ,where the main programs that control the module functions are executed, and a devicecalled Terminal Interface (TI) , which allows the communication between the module andthe other modules in the exchange through the switching network.

There will be modules in the system that have no associated circuitry. These modules areknown as ACEs (Auxiliary Control Elements) and their only relation with the exchange HWis their connection to the network through the Terminal Interface. Therefore, these moduleswill perform support auxiliary functions for the rest of the system. Given their HWindependence, the functions are assigned to these control elements with more flexibility thanto the others, and they may be replaced by others in case of failure. Some examples offunctions that will be carried out by the ACEs are: prefix analysis, charge analysis, trunkresource allocation, statistics, etc.

We will first study the structure of each of the Control Element parts and then their functionsand the circuits associated with each specific module are discussed.

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2.2.1 Terminal Interface

The terminal interface is the component that enables the control element to use thechannels of the network PCM links. Thanks to the TI, a control element will be able totransmit data packets addressed to another TCE, and also to receive data packets comingfrom other control elements.

Another important function of the TI is to accept the two PCM links originated at the modulecircuitry (line circuits, trunks, etc.) and establish the port and channel switching towards thenetwork. All these functions are performed under processor control or, in some cases, arecommanded by the channel content in the same way as the switch works.

The TI employs four pairs of receiver/transmitter ports, two pointing towards the network andtwo towards the module circuitry, to perform its functions. There is a fifth receiver portconnected to tone distribution in such a way that a tone can be sent to a line circuit. Eachreceiver has two software selectable inputs, one of which (except for port 5) is alwaysconnected to the pair transmitter port, for test loop purposes. This structure is depicted in thefigure below.

The link that arrives at port 5 from the tone generator carries the samples of each specifictone along fixed channels. Therefore, the emission of a given tone towards a terminal willsimply consist of port and channel switching under the control of the processor. Port 5receives two input PCM link, and has no transmitter.

Furthermore, the TI includes a 2 or 4 KWord RAM memory called Packet RAM . Themicroprocessor uses it for the transmission and reception of data packets. The packets to besent are written into a specific part of the RAM, which contains the Select commands forsetting up the path through the network and the data to be transmitted. The data must be 64words length or less. On the other hand, the receiving packets are not written into RAMrandomly, instead, discrete areas of 64 consecutive words must be used. Themicroprocessor uses two specific words from its memory map for carrying out its orders overthe TI.

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Figure 34 : Terminal Interface basic structure

R1

T1 R2

T2

R3

T3 R4

T4

TO / FROMNETWORK

TO / FROM

CIRCUITS

TONES A

TONES BR5

Therefore, the final structure of the TI is as shown in the following figure.

Figure 35 : Terminal Interface structure

R1

T1

R3

T3

R5

R4

T4

R2

T2

2/4

KWORD

MICROPROCESSOR

ORDERSANDDATA

PACKETS

Before we see how the processor handles the above–mentioned memory, let us enumeratesome of the most important channel states, that is, the possible states of the channelsarriving at the receivers and of those leaving the transmitters. Thus, looking at a receiver, theincoming channels may be in one of following states:

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� FREE: The channel is not switched, and clear protocols are received in each frame.

� PUT TO RAM: The channel content is written into a specific RAM address each time it isreceived:

Figure 36 : ’PUT TO RAM’ state

CH X CH X

� CUT THROUGH: The channel is linked to a transmitter outgoing channel:

Figure 37 : ’CUT THROUGH’ state

CH X

CH Y

� RECEIVE PACKET: The channel is receiving a data packet sent by another controlelement through the network. Every time this channel time is reached, its content isloaded into consecutive positions of the RAM starting at a specific initial address:

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Figure 38 : ’RECEIVE PACKET’ state

CH X CH X

Similarly, the transmit channels may be in one of the following main states:

� IDLE : The channel is not assigned to any channel of any receiver to establish aswitching step with it, nor is it being used by the processor for data transmission. Achannel in this state sends CLEAR protocols.

� LAUNCH : A channel in this state will launch the data contained in a RAM area starting ata specific initial address provided by the processor:

Figure 39 : ’LAUNCH’ state

CH X CH X

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� FETCH : A transmitter channel in this state will go to RAM to “fetch” (extract) the contentof a single memory position indicated by the processor:

Figure 40 : ’FETCH’ & ’INDIRECT CUT THROUGH’ states

CH X CH X

CH Z CH Z

Using the FETCH state in combination with the corresponding PUT–TO–RAM of a receivingchannel, it is possible to join both channels. This feature is calledINDIRECT–CUT–THROUGH.

� CUT THROUGH : In this state, the transmitter channel is linked to a receiver channel:

Figure 41 : ’CUT THROUGH’ states

CH X

CH Y

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The COMMANDs procedure is used to modify the behavior of the channels. TheCOMMANDs are orders written by the processor into two reserved memory words and readby the port whose identity is written into a third register.

Figure 42 : Transmission of orders to Ports

R1

T1

R3

T3

R5

R4

T4

R2

T2

O

P P

COMMAND WORDS

PORT IDENTITY

ORDER &PARAMETERS

DIRECTEDTO PORT P

1 2

P

3

4

µ

1. The micro writes the command code (’o’) and the parameters (’p’) into the com-mand words.

2. The micro writes the target port id. into a register.

3. Every port periodically scans this register. Only the addressed port is triggered.

4. This port reads the command order (’o’+’p’), and executes it.

With the above–described procedure, the processor will order the transmission of a datapacket addressed to another Control Element:

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Figure 43 : Packet transmission


PACKETRAM

16

COMMAND WORDS

PORT IDENTITY

1

2 3

4

5

6

ÌÌÌÌÌÌÌÌ

018

6

CH X

Pµ

1. Writing of packet to be sent:

– SELECTs to establish network path

– SOP (Start Of Packet flag)

– Data

– EOP (End Of Packet).

2. Writing of command:

– Launch packet through any free channel

– Memory address where the packet is located.

3. Writing of the identity of the port to be used for the launch.

4. All ports read this register.

5. The “called” port reads the command words.

6. The command is executed by writing the words as successive contents of the chosen channel.

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The packet launched is received, through the network, by the TI of the destination ControlElement. The reception proceeds is as follows:

Figure 44 : Packet reception

ÌÌÌÌÌÌÌÌ

PACKETRAM

FREE

FIFO

EVENT R.

EVENT

1

2 3

4

7

6

CH XCH XCH X EOP

SOP

P

4

5

8

1

EVENT CONTENT:

–PACKET RECEIVED

– USED ADDRESS

µ

1 The receiver detects the Start Of Packet indicator, SOP.

2. It looks in a FIFO for the address of a free packet area in the P.RAM.

3. Starting at this address, it writes the successive channel contents (packet).

4. When the receiver detects the EOP, it enters the event into a register:

– Arrival

– Incoming channel

– Address.

5. This situation is recorded in an external register, indicator of ports that have events. This register is periodically read by the processor.

6. When the processor reads in the register that a receiver has an event, it reads the event (by executing a command), and finds out that a packet has arrived and where the packet is in RAM.

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7. Finally, the processor reads the packet and registers the packet address as free in the FIFO so that it can be used again.

In some A1000 S12 System modules, the module circuitry contains a local processor, theOBC (On Board Processor) . This processor has the asset of being able to send and receivemessages to/from another OBC or another system Control Element, by establishing a pathin the TI as if it were one more network stage.

Figure 45 : OBC – OBC communication

C X

C Y

C Z

MULTIPORT

MULTIPORTCLUSTER

OBC

TCE

T I

TCE

T I

CLUSTER

OBC

MULTIPORT

This is possible because the incoming channels of the TI receiver ports accept selectioncommands in the same way as multiport ones do. These commands carry out the operationcalled TRANSPARENT SELECTION.

2.2.2 Processor

The processor will be the part of the Control Element in charge of coordinating the moduleperformance. To achieve this, the processor will basically carry out two types of operationsthrough the Terminal Interface:

� Set up space–time switching between the channels of the different ports.

� Occupy channels in the outgoing PCM links to send data packets (messages) to otherCEs through the network, or to the actual module circuitry.

The information that goes from the TI to the network through the different channels of thePCM links, will undergo successive space–time switching steps to arrive at the destinationControl Element through the appropriate channel. There, it will be captured by the processor(in the case of messages) or switched towards the circuitry of the module in question.

For the processor to be able to carry out its functions, it must be provided with a 1, 4 or8–Mbyte memory, where the different programs to be executed at any given moment will bestored.

2.2.3 Physical implementation of the Control Element

Originally, the Terminal Interface occupied a whole board known as TERI, while theprocessor occupied several boards, one with the actual processor and several with the

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memory. Later, the processor and the memory were integrated into one board calledTCPA/B. Nowadays, the whole control element is contained in a single board of which thereare several different versions:

MCUA : In this particular version, the microprocessor used is the 8086 or a compatible. Themicroprocessor is clocked at 8 MHz and addresses 1 Mbyte of memory. In this example thePBA is used as TCE for subscriber and service circuit modules.

Figure 46 : MCUA structure

8086

RAM

1 Mbyte

MEMORY

BUS

PROM

INTERR.

CONTROLLER.

PROG. CLOCKPROT. RAM

TO

NETWORKTO

CLUSTER

C&T

SERIAL OUTPUT

TI

MCUB : The microprocessor used is the 80386 or a compatible. In System 12, a 4 MB, 8MB and a 16 MB variant of the MCUB are used. The microprocessor is clocked at 16 MHz. Itis used in some modules (i.e. Peripheral and Load TCE, N7 Digital Trunk modules,..), andfor the ACEs. Besides the larger RAM capacity, the memory bus goes out as a “multimaster”bus, allowing the MCUB RAM access to be shared with an external processor.

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Figure 47 : MCUB structure and RAM sharing

80386RAM

up to16Mbyte

PROM

PROG. CLOCK LOCK RAM

TONETWORKTO

CLUSTER

C&T

INTERR.Controller

MEMORYBUS

EXTERNALMULTIMASTERSERIAL

INTERFACE CONTROLLINES

BUS

TI

80386RAM

OTHERPROCESSOR

BUSCONTROLLER

MCUBRQ

RQ

sharedaccesses

BUSGRANT

MCUC : The microprocessor used is the 80486DX2–66 or a compatible. In System 12 a 16MB, a 32 MB and a 64 MB variant are foreseen. The MCUC is primarily used for ACEs,especially for the SCALSV.

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Figure 48 : MCUC structure

80486

RAMup to64 Mbyte

PROM

PROG. CLOCK LOCK RAM

TONETWORKTO

CLUSTER

C&T

INTERR.Controller

MEMORYBUS

EXTERNALMULTIMASTERSERIAL

INTERFACECONTROL

LINES

BUS

TI

80486

RAM

OTHER

PROCESSOR

BUSCONTROLLER

MCUBRQ

RQ

sharedaccesses

BUSGRANT

Cache8Kb

MCUE : due to the unavailability of 8086 and compatible processors, a new board has beendeveloped, fully compatible with the MCUA, and used to replace the MCUA in newexchanges or when existing exchanges are extended, and this for modules such as linemodules, improved service circuits modules, high performance common channel signallingmodules, ... . The microprocessor used on the MCUE is the 32–bit 80386EX, running at a speed of 25Mhz. In System 12, an 8 MB version is provided, extendable to maximum 16 MB. Comparedto the MCUA, a performance improvement of factor 4 has been noted.

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Note : Although the MCUE has initially been developed to replace the MCUA, and therefore hasbeen provided with a low speed bus (LSB), the devolpment has been done in such a way that it canalso be used instead of a MCUB. This is valid for modules such as the ISDN Subscriber Module, theISDN Remote Interface Module, ...

The following table gives an overview of main characteristics of the existing MCUx’s.

Table 1 : CE Overview

MCUA MCUB MCUC MCUE

8086 80386 80486 80386

8 Mhz 16 Mhz 66 Mhz 25 Mhz

1 Mbyte on boardRAM

up to 16 Mbyte onboard RAM Current variants: 2,4, 8 and 16 Mbyte

up to 64 Mbyte onboard RAMCurrent variants: 16,32 and 64 Mbyte

up to 16 Mbyte onboard RAMCurrent variants: 8and 16 Mbyte

serial output serial output serial output serial output

Multiplexed bus

LSCB (speciali )

HSB/MMB HSB/MMB LSB (special variant)

HSB presently noti d ( d ivariant) required (update is

possible)

Note : The name MCUE given to that new module suggests that there should also be anothermodule, called MCUD. This is indeed the case : the MCUD is a high–performance Pentium–basedprocessor–board. It is not mentionned in the previous list, because up to now, it is not used in anyEC7.4 SW release.

All MCUx have three LEDs whose meaning is shown on the figure. The fast test isperformed by a PROM stored program which tests the TI, the memory, and the bootstrapchecksum.

If this fast test is successful, the Bootstrap program is started which requests the CEdownloading. If not one of three possible failures is shown.

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Figure 49 : MCUx LEDs meaning

1

1

1

FAST

TEST

RUNNING

OKLOAD REQUEST

0

0

0

END OF LOAD

INDICATION

X

X

X

OK

1

0

0

ACTIVE

1

1 TI failure

0 1

0 RAM failure

1

0 Bootstrap–

1 Checksum

0 failure

X = BLINKING

1 = LIGTHING

0 = OFF

2.2.4 The On Board Controller (OBC)

In many modules, the module circuitry contains its own resident processor which is in chargeof routine and initialization tasks, relieving the Control Element of these functions. For thisOn–Board Processor to work, a standardized interface is located in the module circuitry. Thisinterface is called OBCI (On–Board Controller Interface) and allows for the OBC–TCEdialogue and the direct handling of channels by the OBC, and also for the dialogue withother OBCs/TCEs in the network:

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Figure 50 : OBC communication

POBC

OBCI

MCUx

PCMLINK

PCMLINKS

PCMLINKS

OTHER TCEsOR OBCs

µ

Similar to the terminal interface, the OBCI contains some PCM ports. With in channelcommands sent to the correct OBCI (using an address because more than one OBCI can beconnected in parallel) connections can be established to send data, ... Also connectionstowards the OBC processor are possible (the OBC is connected via a parallel bus usingDMA channels to pass data to and from the OBCI).

For packet sending between the TCE and the OBC, it is possible to establish temporarypaths. For call connections (e.g: trunks ) it is possible to make fixed connections which existuntil a release command is given.

2.3 Description of the different hardware modules

2.3.1 The Analogue Subscriber Module (ASM)

Each of the A1000 S12 modules is dedicated to a specific task. The Analogue SubscriberModule provides the line end circuit for the analogue subscribers.

Each module is made up of ALCN boards (Analogue Line Circuit board type N) andeach board handles sixteen analogue subscribers. The module is composed of eight ALCNboards, thus serving, 128 subscribers. There exists also a RNGF boards for ring currentgeneration, the TAUC for testing and the RLMC board for alarms (these PBAs onlyimplemented in some of ASM modules: two TAUC and two RMLC per rack). All these PBAsare connected to a MCUA/E type control element via two PCM links. Every two controlelements of the subscriber modules are connected in such a way that each has access tothe ALCN boards of both, and all of these sixteen boards may be handled by one of the twocontrol elements in the case of failure of the other one. In A1000 S12, this connection modeis known as CROSSOVER (represented as ’X–OVER’).

Note : Besides the ALCN, another board can be used : the ALCP, which makes also uses of thelatest CLSI techniques, but only provides connections to maximum 8 subscribers. This board was

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developed in such a way that it is compatible with ELC technology, and can therefore be used asreplacement of the older ALCB on the E–Rack family. In the following text, we will only refer to theALCN. The reader should be aware that the text is also valid for an ALCP.

Figure 51 : Analogue Subscriber Module structure

ALCN

RNGF

TAUC/RLMC

0

15

ALCN0

15

A

B

A

B

MCUA/E

TO THE

NETWORK

PCM LINKS4 Mb/s

16 x 4 = 64

64 x 2 = 128 LINES

5

8

4

1

ALCN0

15

A

B

8

5

ALCN0

15

A

B

4

1 MCUA/E

TO THE

NETWORK

16 x 4 = 64

64 x 2 = 128 LINES

ASM ’A’

ASM ’B’

The following functional blocks are found in each ALCN board:

1. Input resistance and relay contacts to the test (TAU) and ring (RING) buses, in general: Input interface.

2. Transmission interface (one per line).

3. Digital signal processing block (analogue to digital conversion). (One block per every four lines.)

4. MCUA/E interface block. One per board.

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Figure 52 : ALCN functional blocks

TAUBUS

RINGBUS

TRANSM.

INTERFACE

DIGITAL

PROCESS.

SIGNAL

INTERFACE

WITH THE

CE (MCUA/E)

DPTC

ALCN

PCM LINKS

TO MCUA/E

0

1

2

3

0,34,7

8,1112,154 x 4 = 16 LINES

The main functions of every block are:

� Input interface

– High Voltage protection (=line protection)

– Relays to connect the line, send ringing current, execute in/outward tests,...

– Resistors to detect off hook and on hook

– Overcurrent protection.

� Transmission Interface

– Couples voice band signals to the line

– Supplies DC current to the subscriber (48/60V)

– 2 to 4 wire conversion.

� Digital Signal Processing

– A/D and D/A converters: conversion of the analogue speech signal into an 8–bit logarithmic sample and vice versa

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– digital and analogue filters

– gain control: switching an attenuation / amplification network into the subscriberterminal circuit in order to maintain a specified transmission level

– echo cancellation.

� DPTC (Dual Processor Terminal Controller)

– Interface between subscriber terminals and even/odd TCEs

– Control of the line functions upon reception of TCE commands

– Informing the TCEs about HW events (errors, off hook, ...).

The PCM inputs and outputs of the four digital processing blocks are joined and connectedto the processor interface (DPTC) . There, they enter into channel switches that, accordingto the appropriate control, associate the fixed channel of each line with one of the channelsof the two PCM links that go towards the two MCUA/Es (X–OVER).

The controls are performed by the control element based on the transmission of messagesthrough channel 16, which is reserved for this use. The messages are delimited with theSOP–EOP (Start and End of Packet) flags. After the SOP, a DPTC address byte is used todrive the message towards a particular DPTC. The data bytes contain codes that are usedto read or write from/into different control registers contained in the DPTC and, significantly,the bytes of a memory composed of 16 sets of eight bytes each (one set per line), alsocontained in the DPTC. Each bit of the bytes in these sets handles a certain control of theline associated with this set. In order to send the different controls, the bits are transmittedserial, periodically sweeping the memory, towards the four digital processing blocks and,from each of these, to the four transmission interfaces. Each line will take only the controlsthat are addressed to it.

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Figure 53 : Control Paths

ÌÌÌÌÌÌ

LINE 1

LINE 160

7

0

7

REGISTERS

ONLYCHAN. 16

CONTROL MEMORY

DIGITALSIGNAL PCM

4 Mb.

TO / FROMMCUA/E

X_OVER

INTERFACE WITH PROCESSOR (DPTC)

PROCESSING

SERIAL CONTROL OUTPUT

SERIAL EVEN RECEPTION

� Working principle:

The DPTC contains some registers and 16 maps with data (one map/subscriber). Wheneversomething happens (subscriber on hook, ...) it is stored in the correct map (a bit toggle).Then it is up to the DPTC to inform the TCE. This is done by sending a CH0 alarm which isreceived in the Packet RAM of the terminal interface. The SW reads this location regularly todetect the CH0 alarm in time. Upon detection, the SW sends commands towards the DPTCs(the CH0 alarm doesn’t explain ’what’ has happened and doesn’t explain ’which’ DPTCgenerated the alarm).

When the DPTCs receive this polling command, they will report the events (e.g: DPTC of the2nd ALCN, the 3th subscriber lifted the handset) This information is also called a mismatch. All DPTCs have the opportunity to report their events one by one (a cyclic., timedmultiplexed algorithm).

It is also possible to send information towards the hardware. E.g: to switch the relays (tosend ringing current), the SW launches commands towards the correct DPTC to changedata in the map of the correct subscriber (1..16). After that the DPTC sends this informationto a decoder to drive the relays.

Remember:

– The HW informs the TCE about events by sending a CH0 alarm (subscribermismatch, HW error or SW error)

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– The TCE SW can send commands to the HW and/or retrieve information from theHW by sending and/or receiving information via CH16.

� The module is completed with a RNGF board for ring current generation. The function ofthis board is to generate the ringing signal to send through any of the lines. To performthis function, the board contains two current generators from which two pairs of wires goout, each covering 64 subscribers. In each of these boards the ring current is applied orcut with the adequate cadence, by closing the appropriate relay. For more informationabout the ringing, see the chapter of the local call in PART II.

� Rack layout

Given the high integration of each board, up to twelve line modules may be located in asingle rack , connecting the control elements of every two modules according to theX–OVER method.

Figure 54 : ASM location

X_OVER

AIR BAFFLE

ÌÌ

ÌÌ

MCUA/E RNGF MCUA/E RNGF

RACK TYPE

ALCN

JA00

1 18 82 2

One module occupies only ten of the sixteen slots in each subframe side, leaving six freeslots for other boards and converters. One rack contains two measuring boards, TAUC (oneper side), that depend upon the two control elements of two concrete modules. Each ofthese boards sends a measurement bus, that covers all the modules on one side (right orleft).

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Figure 55 : Measurement bus distribution

ÌÌÌ

ÌÌÌ

ÌÌÌ

ÌÌÌ

ÌÌÌÌ

AIR BAFFLE

MCUA/E

TAUC

ALCN

PCM LINK(X_OVER)

METERINGBUS

The two RLMC PBAs are connected in a similar way, .

� TAUC description

Each TAUC board, used to carry out measurements, is formed by two distinct parts: one thatphysically takes the measurement and another one that processes it.

For the physical measurement, the TAUC contains a series of measuring devices andgenerators connected to the test bus by relays. The contacts are closed, assigning onedevice or another, according to what is written in the interface with the control elementsimilar to that used in the ALCN boards (DPTCs). To connect the test bus to the subscriberline, a command is sent towards the correct ALCN to close the relays.The TAUC executesthe measurement and evaluates the result (Digital Signal Processing part). Test results canbe sent to the TCE via a dedicated channel and further on to the maintenance.

Thus a measuring circuit is used to observe the line voltage, for a fixed measurement range,and to send it, converted to digital, to the control element through the assigned channel. Themeasurement will be carried out over the terminating resistance previously arranged for it.This circuit will serve as an encoder for the transmission of audio signal samples, by closingthe loop with the adequate impedance and fixing the precise range.

In the outgoing direction, the circuit will be able to feed the measurement bus with aprogrammable DC or AC voltage by connecting the signal generator, to transmit audiosignals that obey the samples received from the control element through the adequatechannel.

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The TAUC may be used to carry out different measurements by performing the appropriateconnections through accurate controls. For example, one measurement that may be taken isthe resistance, RL, between the two wires, a and b, of one of the lines.

In the TAUC, there is a processor that is responsible for the required algorithms, such as theRL calculation in the above example. This processor is specialised in Digital SignalProcessing (DSP). It is related to the control element through the same interface used in theALCN board, the DPTC.

Different types of measurements may be taken, not only electrical but also audio signalevaluations. Following the figure examples, a program in the DSP generates a signal withknown frequency and power. The signal is sent to the MCUA/E and from there to the line tobe measured (step 1 of the figure). The line pair is deviated to the measurement bus throughwhich it enters the TAUC where it ends at the simulated ’subscriber’ termination [2].Themeasuring circuit takes samples of the signal received, the samples are sent back via theMCUA/E and re–enter the DSP which evaluates them [3]. Finally, the result is sent to thecontrol element (MCUA/E)[4].

All test procedures are always triggered by the maintenance software. Therefore the resultsare sent to this software at the end of the process.

Figure 56 : Measurement example

MCUA/E

ALCN

TAUC

ALGORITHM

RESULT

DSP

DPTC

MEAS.

CIRCUIT ÌÌ

FREQ. GEN.

RESULT

600 Ohm.

MCUA/E

DPTC

CHANNEL ASSIGNMENT

DIGITALNETWORK

ANALOGUE PART

DIGITAL PART

ÌÌÌÌÌÌ

ÌÌÌÌ

1

1

11

2

3

3

33

4

4

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2.3.2 Digital Trunk Module (DTM)

The function of the digital trunk module is to act as interface between a transmission PCMlink at 2 Mb/s and the system internal links at 4 Mb/s, as well as, in some cases, to act asinterface between the signalling used in the trunk and the exchange control.

Figure 57 : Digital Trunk Module

ÌÌÌÌÌÌÌÌ

DIGITAL TRUNK

CONTROL

NETWORK

DIGITALLINK

ÌÌÌÌÌÌ

ÌÌ

ÌÌ

SIGNALLING

VOICEÌÌ

2 Mb/s4 Mb/s

We may find trunks with multifrequency signalling or with signalling through messages(common channel signalling). All the different trunk modules will have to perform somecommon tasks:

� Clock extraction and conversion of line code to binary

In order to read the incoming bits properly, a 2 MHz clock must be regeneratedresembling as closely as possible the one used at the transmitter side. Thisregeneration is carried out by a circuit through the observation of the incoming pulses.If the incoming signal were to present too many consecutive zeros the clockregeneration would be a difficult task. For this reason, the information is not transmitteddirectly in binary, but so–called ’line codes’ are used:

Figure 58 : Binary transmission

01 0 0 0 0

?

The line code, HDB3 code in Europe (AMI in USA), consists of the transmission ofthree different logical levels (–1, 0, +1). The ’1’s are transmitted alternately as ’+1’ and’–1’. If more than three consecutive zeros are to be transmitted, the fourth zero ischanged to 1 with the same sign as that of the last coded 1.

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Figure 59 : HDB3 transmission

01 0 0 0 0

IS SENT

1 0 0

–1

0 0 01 0

–1

Therefore, it is necessary to reconvert the signal from HDB3 line code to binary at thereceiver side, by performing the inverse task as that performed at the transmitter side.

� Retiming

Each exchange sends data through the transmission link with its own clock, which mayvary to some extent from that of the receiver exchange. Therefore, it is necessary toperform ’retiming’ or adaptation to the clock signal at the receiver side. This isachieved through the use of a memory buffer where the data is written according to oneclock, and read according to the other clock. If the difference between the read clockand the write clock remains for a ”longer time” then using this buffer maximum 1 frameis skipped or read twice (this is called: SLIP). CCITT allows only one slip in 70 days.

Figure 60 : Retiming

PULSESLOPES

HDB3 / BIN

2 Mb/s 2 Mb/s

ADDRESSES

WRITINGLOGIC

RETIMING

MEMORYREADING

LOGIC

RETIMEDSIGNAL

1/24 Mb/s

EXTERNALCLOCK

CLOCKREGENERATION

BUFFER

INTERNALCLOCK

ADDRESSES

� Frame alignment detection

In the transmission link, the start of each of the 32–channel PCM frames is marked bythe repetitive transmission of an alignment pattern every two frames. Therefore it isnecessary to recognize this pattern in order to detect the start of each frame.

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Figure 61 : Frame alignment

ERRORCOUNTER

FRAME ALIGNMENT DETECTOR

HDB3 / BIN

PCMLINK

LOSS OF FRAMEALIG. ALARM

To ensure this recognition, an alignment detector will observe if the pattern is repeatedin channel zero every two frames. The third time that this process fails, the system fallsin the alignment loss state and an alarm is produced.

It is possible that the alignment pattern is not observed where it should be, but if thisdoes not occur three consecutive times, the system will not fall in the mentioned state.These error situations are counted and read by the control which, when a threshold isexceeded, produces an excessive error rate (ERR) alarm.

� CRC4 detection

As an added protection procedure, CCITT recommends the use of the CyclicRedundancy Code CRC4, which consists of the elaboration of a 4–bit checking codetaking as input all the bits in eight frames. The code, C1C2C3C4, is sent in the first bitof the four zero channels that carry the frame alignment pattern in the eight followingframes. This first bit is not used for alignment since the alignment pattern consists ofseven bits only.

The receiver side elaborates its own C1C2C3C4 character every eight frames andcompares it with the one it receives in the eight following frames. With the comparisonresult, the receiver side accepts the reception as valid or not, and produces an alarm inthe second case.

Figure 62 : CRC4

0 0 0 0

FRAME 0 FRAME 7

CRC CODE C1 C2 C3 C4

C1 F.A.P.

C2 C4

C3 F.A.P.

F.A.P. F.A.P.F.A.P.= FRAME ALIGNMENT PATTERN

FRAME 0 FRAME 7

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a. Modules that handle multifrequency signalling: Digital Trunk Module Low

The PCM transmission link has its frames organized into groups of sixteen frameseach, called multiframes. The groups are recognized by a specific pattern that travelsthrough channel 16 of frame 0. The channels 16 of the subsequent frames are used forthe line signalling of two of the link channels: channel 16 of frame 1 for the signalling ofchannels one and seventeen, that of frame 2 for channels two and eighteen, etc. Fourbits are used for the line signalling of each channel.

Figure 63 : CAS signalling

ÌÌÌÌÌÌ

ÌÌÌÌÌÌ

ÌÌÌÌ

16 16 16

FRAME 0 FRAME 1 FRAME 2

a b c d a b c d a b c d a b c d

LINE SIGN.CHAN. 1

LINE SIGN.CHAN. 17

LINE SIGN.CHAN. 2

LINE SIGN.CHAN. 18

MULTIFRAMEALIGNMENT

These four bits will represent the line signalling variations corresponding to the mostcommonly used trunks, in the same way as the E and M pair are used in an E and Manalogue trunk to indicate the trunk status.

Figure 64 : Line signalling

M = + E = + Ready

Ready E = + M = +

M = – E = – Trunk seizure

Acknowledgement E = – M = –

E

M E

M

Taking this system as an example, bit ’a’ would be sufficient for the exchange ofsignalling.

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Figure 65 : CAS encoding

A X X X X

1 M = +0 M = –

FRAME 1

16

This line signalling method is called CAS (Channel Associated Signalling).

Register signalling (transmission of digits and different dialogue controls betweenexchanges), is carried out with different multifrequency signalling systems. Thetelephonic events to be exchanged are represented by a pair of frequencies out of aspecific set of, usually, six different frequencies. In order to detect this signalling, it willbe necessary to deviate the channel towards a service module made up of a DSPAboard (similar to the one described in chapter 2.3.4). This board will have the adequateprograms loaded in the DSP, since each service module will be able to receive andanalyze up to 32 channels of up to eight different signalling systems, such as R2, ...

Figure 66 : MF treatment

X 16

CAS

MF CODE

ANALYSIS

ÌÌÌÌ

Y

DSPASCM

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Figure 67 : Trunk & DSPAs

TRUNKS

X Y

Z

A B

X Y A

Z B ANALYSIS

DSPA

X + Y + Z +.......+ A + B = 32

SCM

The outgoing codes to be transmitted are also generated at the service module, fromwhere they are sent through the network towards the corresponding trunk.

Figure 68 : MF codes transmission

X

DSPA

TRUNK

Y

CODE TOBE SENT

In the A1000 S12 system, there exists two modules which perform all the differenttasks of the CAS digital trunk mentioned here : these modules are called Digital TrunkModule Low (DTM–L), and both consist of only one board : the DTUA and the DTUE.

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Figure 69 : DTUA/E

D T U A/E

NETWORKDIGITALDIGITAL

TRUNK

2 Mb/s

The DTUA/E contains the Terminal Interface, the processor and the TCE memory, plusthe typical trunk functions included in a single block.

As shown on the next figure, the board consists of: a digital trunk physical interfaceblock that contains the adapting and isolation transformers, the loop that allows thefeed–back of the outgoing signal and the circuit to extract the 2 MHz clock (thisextracted clock may be wired with the Clock and Tone modules to serve there as amaster reference –see further–).The Trunk Access circuit (TRAC) contains, in a single LSI circuit, the logic forHDB3–to–binary conversion, retiming, frame alignment handling, CAS extraction,multislot handling and management of the different alarms (Trunk Interface).

The circuits that act as the TI and the actual control element are also located on thesame board. The control element is composed of the processor, its PROM and RAMmemories, and a number of associated circuits (interrupts, clock, etc).

Using the DTUA/E, the processor reads the CAS received for each channel from theTRAC memory, and writes the CAS to emit. The conversation channels are switchedtowards their destination at the on–board TI. This destination may be another trunk, ananalogue subscriber or a service circuit, depending on the current call phase.

The next table gives an overview of the main characteristics of both DTM–L’s. The nextfigure shows schematically the layout of the DTUA.

Table 2 : DTUA vs. DTUE

DTM–LDTUA DTUE

1 PBA = 1 module 1 PBA = 1 module

Single trunk Single trunk

CAS or no signalling CAS or no signalling

Blue Book (CRC4/Ebit) Blue Book (CRC4/Ebit)

8086 80386EX

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1 Mbyte 8 Mbyte (up to 16 Mbyte)

2 x QUAP+ POCO 2 x QUAP + POCO

TRAC TRAC

No FW Loadable FW

Not DTRE compatible Not DTRE compatible

No RLMA connection No RLMA connection

No X–over No X–over

Figure 70 : DTUA block diagram

HDB3 /BINRETIMINGFRAME ALIGN.CRC4MULTI–SLOTALARMS8 / 16 BITS

PROM, RAM

PROCESSOR

TI PART

ACCESS CIRCUITTO TRUNK (TRAC)

PHYSICAL INTERFACEWITH THE LINE

DTUA PBA

2 Mb/s

EXTERNAL RECOVEREDCLOCK (2 Mb/s)

TO C&TMODULE

8086

The DTUE is designed as a low cost alternative to replace the DTUA. The functionality of theDTUA is limited by

� The restricted performance of the on–board processor

� The 1 Mbyte memory capacity

These restrictions are erased with the inroduction of the DTUE. Based on a MCUE (with80386EX microprocessor) as TCE part and the implementation of minimum 8 Mbyte (up to16 Mbyte) of memory capacity, the DTUE stands for an increased performance with at leasta factor 3 compared to the DTUA.

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The DTUE shalll support both the real mode and protected mode operation by providing theVirtual Machine Motor (VMM) and the Common CE–SW Interface (CCSI) in one FPROM.The DTUE will run the same real mode code as the DTUA. This will be realised by theVMM.In addition a hardware independent CCSI shall be provided for protected modeoperation. This shield avoids direct HW accesses by the SW. This funtion will beimplemented on all new processor boards to avoid SW impact in case of future HW changesin the processor area.

Figure 71 : Signalling & speech channels path

31

01

DTUA/E

MCUA/E ALCN

CAS

TI16 X

Y Z

X

CE

16

The CAS digital trunk module (DTM_L), based on the DTUA/E board, are linked to thenetwork forming high traffic TSUs, that is, TSUs of four modules each. A JH00 rack mayhold up to fifteen of these TSUs. Where such a large implementation is not required, theDTM–L modules may be located in several positions of other rack types:

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Figure 72 : DTM–L physical situation

AIR BAFFLERACK TYPE

JH

1 2 3

4 5 6

7 8 9

10 11 12

151413

SWITCH

DTUA/E

AIR BAFFLERACK TYPE

JB

SWITCH

DTUA/E

ÌÌÌÌÌÌÏÏÏÏ

ÌÌÌÏÏÏÏÏÏ

ÌÌÌÏÏÏ

ACE

ISCM

b. Modules that handle common channel signalling: Digital Trunk Module High.

In common channel signalling, one channel of one of the links that make up a route isused for the transmission of signalling messages. These messages, conform to CCITTNumber 7 recommendation, may be related to any route channel, that is, to channels ofthe same link carrying the signalling or channels of a different link. A route is usuallyformed by at least two links for reliability purposes. In A1000 S12, links that do not

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carry N7 signalling are implemented with Digital Trunk Module Low as seen in theprevious section.

Figure 73 : Common channel signalling

1

2

3

4EXCHANGE A EXCHANGE B

CHANNEL WITH SIGN. MESSAGE

ANY CHANNEL IN ANY LINK A –BSIGNALLING

MESSAGE

The N7 signalling messages have the following structure:

The 64 Kb/s of a signalling channel are organized into frames delimited by two 8–bitflags. These frames are given a sequence number when sent forward (FSN: ForwardSequence Number) and recognized backwards on the basis of the said number (BSN:Backward Sequence Number). The frame data field is used for the transmission of theactual message. This field contains the following sub–fields: the message length, theorigin, the destination and the trunk and channel identity within the trunk to which themessage is referred (CIC) .

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Figure 74 : Number 7 protocol

0 1 2 3 4 5 6 72 Mb/s

CHANNEL DEDICATED TO SIGNALLING(USUALLY CHANNEL 16)

LENGTH

ORIGIN

DESTINATION

LINK / CHANNEL

BODY

OF THE

MESSAGE

FSN

FIB: TOGGLED TO INDICATE START OF RETRANSMISSION

FRAME N IS FORWARDED

BSN

BIB: TOGGLED TO REQUEST RETRANSMISSION

FRAME N. RECEIVED

FLAG CRCÌÌÌÌÌÌÌÌ

FSN BSN FLAG

8 16 MESSAGE 8

VERIFICATION

CODE

LEVEL 2 FRAMES

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

NEXT FRAME

64Kb/s

FIRST BIT TO BE SENT

CIC:

CIRCUIT

IDINTIFICATION

CODE

(LINK & CHANNEL)

A digital trunk with N7 signalling will look for the channel dedicated to signalling at thebeginning of each frame, check its uncorrupted reception (CRC ) and send theacknowledgement for the frame uncorrupted arrival in the next transmission in theopposite direction. From the actual message data, the trunk will determine whether themessage is directed to ’this’ exchange or to another one. In the first case, the trunk willpass the message to the digital trunk module in charge of receiving the link and voicechannel to which the message is referred. In the second case, the trunk will send themessage to the trunk handling the outgoing signalling channel that will reach thedestination point. This function is named Signalling Transfer Point. In the N7 protocol,all these functions are named MTP (Message Transfer Part) level 3 discrimination,distribution and routing functions.

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Figure 75 : Routing and distribution

CH 16

CH 16

ÌÌCIC

CH 16

BSN = FSN RECEIVEDBIB = 0, FRAME OK

O.K.

DTM HIGH

DTM HIGH

DTM LOW

DTUA

ROUTING

DISTRIBUTION

Destination

– detects the frame (flags) and checks CRC

– if OK, acknowledges uncorrupted reception

– if the destination is:

. this exchange, sends message to the digital trunk that receives the indicated channel, identified by the CIC indicator (distribution).

. another exchange, sends message to the digital trunk that handles the appropriate signalling channel (routing).

A continuous flux of ’filling’ frames or FISUs, i.e. frames without data field, is sentbetween the frames with data fields (messages), called MSUs (Message SignallingUnits). The FISUs do not increment the FSN field, but may use the BSN field foracknowledgements.

There are two different types of DTM–H which are capable of handling N7 signallingmessages : the IPTM and the DTUB.

� The IPTM – module :

The IPTM basically consists of two boards : a DTRI and a MCUB. In the first board, theDTRI, we find the same digital trunk physical interface as the one used in the DTUA,with the possibility of setting the test loop; and, also, the same Trunk interface with thecommon functions of HDB3–to–binary conversion, retiming, CRC4, frame alignmentand multislot service, but without making use of the CAS extraction function. The voicechannels, once time–adjusted and converted from 8 to 16 bits, pass through the TRACand go to the MCUB for subsequent routing through the network.

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Figure 76 : IPTM structure

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

1 2

3

4

LIN / OUT

CH X, CH Y

TRAC

RAM

OBC (386)

OBCI

ILC

MEMORY BUS

PHYSICALINTERFACE

DTRI

MCUB

2 Mb/s

IPTM

EXTERNALCLOCK

Although channel 16 is usually the signalling channel, there may be as many as four.The signalling channel passes through the TRAC, also in a transparent manner, but isswitched through the TI, reflected in the Access Switch, sent back through the TI and atthe OBCI towards the ILC.

This ILC circuit (Integrated Link Controller), which is, pre–programmed by the on–boardprocessor OBC, observes the arrival of the messages (flag detection). The ILC thenpasses these frames to a memory and notifies the OBC when this process ends. TheOBC deals with the level 2 & MTP level 3 distribution and routing functions. Thereforethe OBC sends the message through the OBCI, the MCUB and the network to theDTUA that handles the associated speech channel or to the IPTM that reroutes themessage to the destination exchange (Signalling Transfer Point).

The channel 16 loop is handled in this way to make it common, from a software point ofview, in case an IPTM module handles the incoming signalling channel that is received inanother DTM or when a specific HCCM N7 treatment module is used.

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Figure 77 : Message routing and distribution

1 2

3

4

RAM

OBC

ILC

MESSAGE

DTRI

MCUB

2 Mb/s

ÏÏÏÏÏÏÏÏÏ

DMA

ÌÌ

CH Y

CH X

DMA

CH Y

LEVEL 2 TREATMENT

MTP LEVEL 3 FUNCTIONS

ÌÌCH 16

ÌÌCH A

ÌÌCH 16

TRAC

DISTRIBUTION

AND ROUTING

DTUA

IPTM

OBCI

ÌÌ

CH 16

Therefore, a route with N7 signalling is composed of a certain number of links without anysignalling channel, based on the DTUA board (CAS handling logic omitted), and at least twolinks with a signalling channel each (usually channel 16), used to transmit and receive theN7 messages. These signalling links are based on the DTRI board.

Figure 78 : Route structure

ÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌ

ÓÓÓÓEXCHANGE A EXCHANGE B

MESSAGES RELATIVE TO ALL THE

ÓÓÓÓ

SPEECH CHANNELS IN THE ROUTE

DTUA

IPTM

SPEECH CHANNELS

DTUA

IPTM

Since the IPTMs (Integrated Packet Trunk Modules) do not handle all the links of a route, butonly those links carrying N7 signalling, only a few of them are implemented. The exactnumber of IPTMs that is equipped per route depends on the actual route traffic flow. These

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modules are combined into high traffic TSUs, four modules per TSU. Therefore, one of theseTSUs is implemented inside a subframe of the JH rack.

Figure 79 : Rack JH00 look

ÓÓÓÓÓÓ

1ÓÓÓÓÓÓ

2ÓÓÓÓ

3

ÓÓÓÓ

4 ÓÓÓÓ

5 ÓÓÓÓÓÓ

6

ÓÓÓÓÓÓ

7 ÓÓÓÓ

8 ÓÓÓÓ

9

ÓÓÓÓ

10 ÓÓÓÓ

11 ÓÓÓÓÓÓ

12

ÓÓÓÓÓÓ

13ÓÓÓÓÓÓ

14ÓÓÓÓÓÓÓÓÓ

15

ÓÓÓÓÓÓ

1 ÓÓÓÓÓÓ

15

MODULES WITHOUTSIGNALLING (DTUA)

ÓÓÓÓÓ


ÏÏÏÏÏÏÏÏÏÏ


ÓÓÓÓÓÓÓÓÓÓ

ÓÓÓÓÓ

ÌÌÌÌÌ

ÏÏÏÏÏ


ÓÓÓÓÓÓÓÓÓÓ

DTRIMCUB

SWITCH

RACK JH

SUBRACK

PBAs

ÌÏÏÏÏ

RACK JF

ÌÌÌÌ

ÌÌÌ

ÌÌ

ÌÌÌ

ÌÌÌ

DTML (DTUA)

DTMH

(DTRI + MCUB)

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Where such a large number of trunks are not needed, the DTM–Ls (DTUA) and the IPTMsmay be equipped in different positions of the other racks, such as the JF. These possibilitiesare show on the previous figure.

� The DTUB – module :

This module combines MCUB and DTRI functions on one board and offers a second 2Mbit/s trunk interface for optional use. The reduction of the HW from 2 to one PBA offersconsiderable cost improvements.

In the first implementation step (from EC74 on), DTUB will replace the current PRA andFrame Handling (PHI) applications of the IPTM module. For low end PRA applications, like «partial » PRA, not making concurrent use of all 30 PRA user channels, the DTUB–variantwith the second trunk interface will offer a further considerable cost improvement.

In further implementation steps (EC75 or later) the one board trunk module could withcomparable, or slightly improved performance replace the present and some further plannedIPTM applications, which require HDLC channels with various protocols (e.g. : IPTM/CCSand IPTM/X.25). Cross–over configurations and connections to the RLMA cannot besupported by DTUB bacsue of non–accessability of cluster links.

The next two figures represent the two DTUB variants. The first is called the 1–trunk variant,having two ILC’s connected to one trunk. In this example the board can terminate up to 4HDLC–channels for that one trunk. The other is called the 2–trunk variant, having two ILC’sconnected to one trunk each. Here a DTUB can terminate up to 2 HDLC–channels pertrunk.

The following table shows a comparison between both available DTM–H’s.

Table 3 : IPTM vs. DTUB

DTM–HIPTM DTUB

DTRI + MCUB 1 PBA = 1 module

Single trunk Dual / Single trunk

Nr7, ISDN–PRA, X31, X25 Nr7, ISDN–PRA, X31, X25

Blue Book (CRC4/Ebit) Blue Book (CRC4/Ebit)

80386SX (+80386) 80386DX

4 Mbyte 8 Mbyte

OBCI 2 x QUAP + POCO

TRAC 2 x / 1 x TRAC

2 x ILC 2 x ILC

Loadable FW Loadable Firmware

DTRE pin compatible DTRE pin compatible

RLMA connection RLMA connection

No X–over No X–over

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Figure 80 : DTUB –1 trunk

2Mbit trunk DSN

DSN

TRK I/F TRAC QUAP 0

QUAP 1

POCO

Tone

I/F

ILC 1 ILC 2

SRAM BA

80386 DRAM(8Mbyte)

INTI

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Figure 81 : DTUB – 2 trunks

2Mbit trunk DSN

DSN

TRK I/F TRAC QUAP 0

QUAP 1

POCO

Tone

I/F

ILC 1 ILC 2

SRAM BA

80386 DRAM(8Mbyte)

INTI

2Mbit trunk

TRK I/F TRAC

1

2

1

2

If the processing capacity of the IPTM/DTUB is insufficient to handle the signallingmessages, the DTUA board may be used to deviate the signalling channels to a specialmodule in a semi– permanent way. This special module is called HCCM (High–performance

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Common Channel Module) and is able to handle N7 signalling messages from up to eightdifferent origins. The structure of this module is described in the following section.

2.3.3 High–performance Common Channel Module (HCCM)

Figure 82 : HCCM structure

12

8

DTUA

MCUA/E

12

3

4 OBCI

RAM

RAM

OBC

(80186)

FLAG

DUAL

PORTMEMORY

SIGN.CONTR.

(8086)

ILC

DMA

SLTA

SLTA

ch 16

ANY CHANNEL WITHSIGNALLING MESSAGE

LEVEL 2PROCESS

ROUTINGANDDISTRIBUTION

The HCCM is composed of a control element and up to eight SLTA boards (Signalling LinkTermination type A). Each SLTA handles one signalling link. With the HCCM, a mucherhigher amount of signalling traffic can be handled : with an HCCM, a total traffic of 8 x 700

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MSU/s can be treated, which allows a traffic of almost 1E per link. An IPTM has a muchlower capacity : as the 4 possible signalling links must all be treated by the same OBC, thetotal capacity is restricted to 540 MSU/s, for the 4 links together (this means a traffic ofapproximately 0.2 E per signalling link).

The signalling channel is conveyed through the network up to the MCUA/E in charge of theeight SLTAs and, from there, sent by a fixed channel i assigned to each SLTA. Once in theSLTA, this fixed channel is switched at an OBCI towards a fixed channel of port 1, which isthen received by an ILC. When the ILC detects the frames, it passes them (without the flags)to a memory by means of DMA.

A dedicated process, known as Signalling Controller, checks the frame uncorruptedreception (level 2 analysis), and passes the message to a double port memory, notifying theon–board processor or OBC. The OBC then reads the message and continues the processaccording to the message destination address. Therefore, it routes the message towards thedigital trunk (DTUA) that receives the CIC voice channel, or towards the SLTA associatedwith the outgoing signalling channel that will be used to reach the destination.

2.3.4 Service Circuit Module (SCM)

This module is necessary for the detection, analysis and generation of the codes of thedifferent multifrequency signalling systems used between exchanges, for the detection andthe analysis of the multifrequency line codes (DTMF), as well as for the realisation ofmultiparty calls.

Figure 83 : Subscriber MF signalling analysis

ALCN

DTUA

Service Circuit Module

fx+fy

a/d

ch x

samples

ch a

ch b

ch bch a

Present code ofthe interexchangesignallingSystem X

Present code ofsubscriber MFsignalling system

ch y

Signalling XTrunk

ch i

MF code f1+f2 samples

The analysis to find out the multifrequency code present in the incoming channels consistsof the use of Finite Impulse Response (FIR) digital filters. These filters consist on theapplication of an algorithm based on the multiplication of a set of samples of the signal to be

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analyzed by a set of coefficients or weighting factors. These coefficients are specific to thefrequency which presence is to be confirmed. The result of the addition of all thosesuccessive products provides the instantaneous amplitude value that the frequency beinganalyzed presents in the channel.

The more coefficients used, the greater the detection precision, but also the longer the timerequired (t = n*125 micros). The use of 128 coefficients is a sensible choice since thatamount is sufficient to comply with the requirements of all the signalling methods.

The receiver will apply the algorithm multiplications and accumulates to find, or not, one andonly one pair of frequencies that present an amplitude higher than a set minimum. It willcarry out this process several times until it accepts the detection as valid for a time longerthan a minimum specified in each system: persistency test.

When multifrequency signalling is used, the Service Circuit Module not only must be able toanalyse the incoming multifrequency signals, but must also be able to emit multifrequencycodes.

Figure 84 : Service Circuit Module

Service Circuit Module

ch b

ch b

MF signallingTrunk

ch i

ch j

fx+fy

fw+fz

ch a

ch d

ch cch c

ANALYSIS

(RECEIVER)

SENDING

(TRANSMITTER)

The SCM specific hardware has sufficient processing power to analyse the incomingmultifrequency codes of up to 32 input–channels (these codes may be MF as well as DTMFsignalling codes, with a maximum of eigth different sets of frequencies), and emit at thesame time all the multifrequency codes of maximum two different signalling systems (eachsignalling system consisting of a set of frequencies in the forward direction, and a set ofother frequencies in the backward direction). This emission is done by placing each fixedcode (e.g. f1+f4) into a fixed channel, dedicating 2 times 15 channels to each multifrequencysystem (15 channels for the forward MF signals and 15 channels for the backward MFsignals). These codes are then to be distributed by the control element to the different TCEs.

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Figure 85 : Used channels on the PCM

SCM

HARDWARE

MCUA/E

ch i

ch j

1 15 17 31

S1 S2

1 17 31

S3 S4

15

Total number ofinput channels= 32

The whole logic required to handle the thirty–two incoming channels of up to eightmultifrequency systems and to emit the corresponding codes in four sets of fifteen channelseach, is located in a single board called DSPA (Digital Signal Processor type A). This PBAcontains a specialised processor for digital signalling handling named DSP, with its ownRAM memory, a set of programmable FIFOs contained in the queues RAM (64Kx16), andthe queues RAM interface LSI named QRC (Queue RAM Controller).

An On Board Controller (80186 or compatible) controls the queues RAM using the QRC andhandshakes with the DSP.

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Figure 86 : SCM structure

DSPA PBA

0 31

0 31

CEMCUA/E PBA

TI

RAMMICROPROCES-SOR.

QueueRAM

QueueRAMinterface

SIGNALPROCESSOR

DSP

OBC80186

64K x 16

RAM

PROM

RAM

interrupt

The OBC in the board initializes the queue RAM interface (QRC), assigning one FIFO toeach incoming channel. This FIFO will receive the samples of the code to be analyzed.

On the other hand, a certain RAM area is reserved in the queues RAM for the exchangesbetween the OBC and the Digital Signal Processor (DSP), which will carry out the adequatealgorithms. A third RAM area is used for the TCE–OBC message exchange.

The CE sends a message, through channel 16, containing a task performance request. Themessage is sequentially written into the queue RAM area that was assigned to channel 16during the initialization.

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Figure 87 : Message to DSPA OBC

CEMCUA/E PBA

TI

RAM

MICROPROCES-SOR OBC

80186

CH 16

Message to theOBC:– Request fora receiver– Ch 1, Sign X

Area assigned tothe channel 16

Message readby the OBC

(Message)

PROM

RAM

The OBC, using this interface area, assigns a FIFO to the successive contents of thechannel to analyze.

The OBC then writes the task performance request to the DSP, indicating the FIFO and theMF system, into an exchange memory area. It then interrupts the DSP which will read thecommand.

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Figure 88 : Task performance request to DSP

CEMCUA/E PBA

TI

RAM

MICROPROCES-SOR OBC

CH 1

DSP

FIFO N

ÏÏÏ

1

2

3

4

OBC–DSPmemoryinterface

5

RAM

Queue RAM interface

Queue RAM

1.– OBC command : assign FIFO N to input channel 1

2.– The OBC requests the DSP to run system X algorithm with FIFO N samples

3.– The OBC interrupts the DSP

4.– The DSP reads the OBC command.

In the assigned incoming channel the CE sends the samples to be analyzed. Through theQRC these are written into successive FIFO addresses. Taking into account the readcommand, the DSP runs the filtering algorithm.

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Figure 89 : Filtering algorithm running on the DSP

CEMCUA/E PBA

TI

RAM

CH 1

DSP

Filtering algorithm

sample 1

sample 2

sample 3

running

RAM

Queue RAM

QueueRAMinterface

MICROPROCES-SOR

The DSP, when it arrives at a conclusion, it writes the result into the DSP–OBC interfacezone of the queue RAM and notifies the OBC by means of an interruption. The OBC thenreads the result.

Figure 90 : Algorithm results

CEMCUA PBA

TI

RAMMICRO

Q–RAM

DSP

RAM

OBC

Q–RAM–ITF

INT

CH 1

The CE sends periodically requests towards the OBC, to ask for results.The OBC preparesa message, with the result found, in the queue RAM area associated with channel 16. Themessage will be transmitted sequentially, through the interface, as contents of this channel(16).

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Figure 91 : Sending of results to the CE

CEMCUA PBA

TI

RAMMICRO

Q–RAM

OBC

Q–RAM–ITF

CH 16

ResultMsg

CH 16assoc. RAM

In parallel with all this, the DSP must be writing, periodically, the FIFOs associated to thechannels outgoing towards the TCE that will carry the different multifrequency codes of thedifferent systems.

Figure 92 : Writing the FIFO

TI

RAMMICROPROC.

DSP

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

PeriodicUpdating

CH1, LINK 1

CH1 LINK 1

CH 31, LINK 2

f1+f2. System 1

f2+f3. System 1

f’5+f’6. System 2

1 2

Queue RAM interface

Queue RAM

RAM

31

These writings to the FIFOs must be performed within the appropriate period so that theFIFO is never emptied, taking into account that the emission period is 125 micros.

Another task carried out by the DSPA is that related to the multiple conference. It offers theConference Bridge service for, typically 3 or 5 parties, but with a capacity for up to 10parties. The speech samples of the different subscribers involved in the multiple conferenceare carried to the DSPA, where the DSP adds them and outputs them through differentchannels of the link going towards the MCUA/E.

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Figure 93 : Conference Bridge

OBC

DSP


ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

A

BC

A+BA+C

B+C

+

Initialisation

Task Request

DSPA

MCUA/EALCN

ALCN

ALCN

Speech A

Speech B

Speech C

A

C A B

A+B

B+CA+C

B

C

B+C

A+C

A+B

The multiple conference may be performed in a simplified way, by simply adding the differentcontributions, or in a complex way, by amplifying the weaker signals and not amplifying thestronger signal at any given moment.

Taking this into account, the DSPA, depending upon the loaded software, may have differentconfigurations, with different combinations of senders, receivers and conference bridges.The following table shows some examples of these configurations:

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Figure 94 : Possible SCM Configurations

Senders Receivers SCB3 SCB5

60 0 0 0

60 16 0 0

60 32 0 0

45 0 0 0

45 16 0 0

45 32 0 0

30 0 0 6

30 0 10 0

30 0 0 0

30 16 0 6

30 16 10 0

30 16 0 0

30 32 0 0

15 0 0 6

15 0 10 0

15 0 0 0

15 16 0 0

15 32 0 0

0 0 10 6

0 0 0 6

0 0 0 0

0 16 0 6

0 16 0 0

SimplifiedConferenceBridge for 3Subscribers

SimplifiedConferenceBridge for 5Subscribers

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The Service Circuit Module is a high–traffic module and is therefore arranged in TSUs offour modules each:

Figure 95 : Service Circuit Module TSU

DSPA MCUA/E

Access Switch

01234567

8

15

Access Switch

01234567

8

15

DSPA MCUA/E

DSPA MCUA/E

DSPA MCUA/E

The whole Service TSU may be implemented in a single subframe:

Figure 96 : Location in JH00 rack

ÓÓÓÓ

ÓÓÓÓ

ÓÓÓÓ

ÓÓÓÓÓÓÓÓ

RACK JH00

SUBRACK

Same PBAs

SWITCH

MCUA+DSPA

ÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌ

ÌÌÌÌ

ÏÏÏÏÏÏÏÏ

ÏÏÏÏ

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2.3.5 Trunk Testing Module (TTM)

This module is used to perform trunk tests for fault detection, and, for periodic checking ofthe service quality offered by the trunks. Several operations may be carried out on the trunksusing of this module, which consists of a Control Element (MCUA/E) plus specific hardware.The TTM will be able to perform measurements on trunks that end in exchanges that,although not A1000 S12, are equipped with devices conforming to the CCITTrecommendations.

Figure 97 : TTM Module

TTM

CLUSTERMCUA/EPBAs

Thus, TTM will be able to evaluate the power and noise level of a voice signal receivedthrough any channel of a link, and to generate any type of voice frequency tone in theopposite direction. The two ends of the link to be measured may ’understand’ each otherthrough the exchange of multifrequency signalling based on the CCITT Number 5 code(ATME2 ). This code may be detected and passed to the CE, and also, generated by it.

The CAS signalling is inserted in the unused bits (1 to 4) of each digital link channel, andswitched towards the TTM where it is observed. The following figures show, some of theTTM test facilities.

On the sender side the TTM function is called DIRECTOR and on the receiving side thefunction is called RESPONDER.

The TTM is also capable of executing ”Service Quality Tests”. This test generates a numberof calls to specified directory numbers in remote exchanges.These DNs are called robotnumbers because they do not correspond with a normal subscriber. A robot is nothing elsethan an automatic answer circuit which can be an external device connected at MDF–levelor a TTM if the remote exchange is a A1000 S12 exchange. The test result indicates thenumber of successful calls (answer).The test result give a good idea of the service quality of the exchange since the hardwareand the normal call handling software is used.

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Figure 98 : In band filters

ch x

Trunk

Exchange ’A’

Test equipment

Digital TrunkModule

MCUA/ECLUSTER

– Signal Filtering and evaluating

( Typical used Filters: Sofometric

and broad band (400/2800 Hz))

DSN

Figure 99 : On demand signal generation

ch x

Exchange ’A’

Digital TrunkModule

MCUA/ECLUSTERTestEquipm.

DSN

– Any combination of three tones in the vocalband with variable power.

– Aleatory Noise

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Figure 100 : In–channel CAS and frame alignment tests

ÌÌÌÌ

Exchange ’A’

Digital TrunkModule

MCUA/ECLUSTER

– SYNC Pattern Observation

– CAS Signalling Obervation

DSN

PCM CAS

0 1 15 16 17 30 31

SYNC CAS Signalling


4 1

Sample CAS

ÏÏÏÏÏÏÏÏ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

XY

Z

W

CH 1

CH 0

ÏÏÏÏÌÌÌÌ

Figure 101 : BER and fixed pattern tests

Exchange ’A’

Digital TrunkModule

MCUA/ECLUSTER

– Periodic Pattern Check or– Delivering to the Control Element of the fixed data sample

DSN

X

Z

1110111.......11111

CH PÌÌÌÌÌÌ

Periodic CCITT patternor

Fixed data sample

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Figure 102 : Two wires and V.24–RS232 interfaces

Exchange ’A’

Digital TrunkModule

MCUA/E

DSN

X

Z

ÌÌÌÌ

CH P

CLUSTER

12

16V24–1 V24–2

External Test Equipmentbased on PC

ExternalTest Equipment

2 wire interface

Figure 103 : In–channel CASDIGITAL TRUNK


CH X

8

CH 16

CH X CAS

1 1 CAS

4 1ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

X

8

CH X

TTM Processing

The TTM is also able to check the uncorrupted reception of the frame alignment pattern fromany link (Line Error Rate or LER test). This module can also generate and check the cyclicpatterns to be inserted into a channel to be tested, as recommended by the CCITT, (Bit ErrorRate or BER test); or fix the sample value to be sent through a channel, invariably the same,and check it at the other end.

Another test that can be performed by the TTM consists of converting to analogue andoffering to the exterior, the signal received through a certain digital link channel. In the same

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way, it can offer the contents of a channel to one of two V.24 interfaces for its connection tothe corresponding measuring device.

All of this is achieved using specific hardware based on the DSPA board, practically thesame board as that used in the Service Circuit Module. The only difference is that the DSPAused here incorporates of an OBCI since without it, it would not be possible to chain the twoDSPAs contained in the TTM to the TCE links.

The module is completed with a MIRB (Modem Interface and Rate Adapter Board) thatpasses the contents of a channel to V.24, and a TDAA (Test Desk Adapter Board) whichconverts up to six channels to analog. These two boards are optional.

Figure 104 : TDAA / MIRB location

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

TDAA MIRB

DSPA

MCUA/E

1 2 3 6

V–24

1 2

Both, the structure and the operation of the DSPA are similar to those of the board used inthe Service Circuit Module, with the before mentioned exception of the OBCI inclusion. Thisinterface provides the means to discriminate between the TCE messages that areaddressed to one DSPA or to the other, given that these messages start with an OBCIaddress that the DSPAs recognize. This configuration makes possible the simultaneousanalysis of up to 30 channels.

2.3.6 Clock & Tone Module (CTM)

This module, essential for the system, is in charge of the generation of the 8 MHz basicclock that will be distributed to all the multiports and control elements, ensuring the systemsynchronism. It is also responsible for the generation of exchange supervision tones as wellas real time. These functions are so important that the module is always duplicated, the twoCTMs working in active/hot–standby mode.

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Figure 105 : Clock and tones module

CTM 1

ExternalReferences

Remote Exchange

DigitalTrunk

ClockGeneration

Feed Back

Double tonedistribution

Double distributionfrom unique

Selection

Selection

MCUB

Tone Generation CTM 2

2Mbps

DTUA/DTRI

DSN

source of clock

Each Clock & Tone Module sends its 8 MHz output signal to the other one. Within eachmodule, the two 8 MHz signals enter a selection circuit where the same signal is selected byboth modules so that, the two parallel clock distributions end up distributing the same clocksignal. That is, the two clocks reaching all the multiports and control elements are taken fromthe same source: the output of the active CTM. The selector changes automatically from onesignal to the other when it does not receive a clock from the selected CTM.

The tones are distributed in parallel to all the control elements. They enter the controlelements through TI port 5 with a fixed channel pattern that is Administration dependent.

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Figure 106 : Clock and tone distribution

5

CLOCK A

CLOCK B

TONE

LINK

TONE

TI

MCUA/MCUB

0123

4

5

67

8

15

8 MHz 8 MHz

LINK

PCM

PCM

10 2 3 4 31

Tone Link PCM

– Tenth of Seconds– Seconds

– Tenth of hours (2 bits)– Hours (4 bits)– Tenth of minutes (3 bits)– MInutes (5 bits)

Tone 1 Samples

Tone 2 Samples

DSE

Each module is made up of the MCUB, the two boards, RCCB and CCLA, for clockgeneration, and one DSGA board for tone generation. The DSGA contains the interfaceregisters used by the control element (MCUA/E) to send and read data to and from the OBC(8086) located in the RCCB.

The CTM performs a priority–based selection at the RCCB of one reference signal. TheRCCB receives four external synchronization signals at 2 MHz from four exchanges linked tothis one by digital trunks, one atomic clock signal that is the same for all the exchanges, theoscillator output of the other CTM and its own oscillator output. The CCLA will track theselected reference signal and, with it, will produce an 8 MHz clock that enters a secondselector that also receives the clock produced by the other module. Both modules’ selectorsare initially set for the selection of one of the clocks, namely the one produced by the moduledefined as A by a backpanel connection. Therefore, at power–up, module A will be theactive and module B the hot–standby module.

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Figure 107 : RCCB and CCLA structure

1234567

From Digital Trunks

12

43

ATOMICCLOCK

+ Priority

2 MHz

RCCB

OBC8086

8 KHz

CCLA

MCUA/E

DSGA

8 MHz

1

TONES

MODULE A

Selector

Active

Divisor

8 KHz

PLL

8 MHz

OSC

1234567

From Digital Trunks

12

43

ATOMICCLOCK

+ Priority

2 MHz

RCCB

OBC8086

8 KHz

CCLA

MCUA/E

DSGA

8 MHz

TONES

MODULE B

Selector

Hot Stand By

Divisor

8 KHz

PLL

OSC0

8 MHz

The two OBCs (A and B) must periodically activate a circuit that supervises the properoperation of the firmware. If, at the active CTM, this periodic activation does not take placeor, the CCLA stops providing a clock signal, the output selector will automatically switch tothe other input in order to receive the signal produced by the other module, which from thatmoment on will be the active one. Given that the two modules’ selectors are joined, theselector will also switch at the other module for it to output its own clock signal since it is theactive CTM.

If all the external references fail, the OSC (oscillator) output is taken as a reference. Eachmodule takes the output of the other one as the highest priority reference.

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The RCCB and CCLA boards have LEDs on their stiffener whose meanings are indicated onthe figure below.

Figure 108 : RCCB and CCLA LEDs

RCCB

PBA

CCLA

PBA

FLL Alarm

OBC Alarm

Voltage to the PLLout of range

(BELLOW)

Voltage to the PLLout of range(ABOVE)

PLL Alarm

Clock outgoing Alarm

Fast test

Fast test

The output of each CCLA/RCCB pair is sent towards a distribution PBA which is calledCLTD (Cock & Tone distribution). From there the clock is distributed again towards each leadrack (every tenth rack), in which another CLTD is located (if there are more than 10 racks,more than one CLTD is needed). From there, the CLTDs distribute the clock signals (bothfrom the same source) to the other 10 racks which contain RCLA boards for further clockdistribution.

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Figure 109 : Clock distribution




ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ



ÏÏÏÏÏÏÏÏÏ




ÓÓÓÓÓÓ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

Switching or CE PBA

CCLA

RCCBCLTD

RCLA

CLTD

JF00

JA00

JB00

Distributionto all CEs andSWITCH PBA insidethe rack

ÏÏÏÏÌÌÌÌÏÏÌÌ

Figure 110 : Clock distribution scheme

Active

CCLARCCB CLTD

Hot Stand By

CCLARCCB

CLTD

CLTD

CLTD

ÏÏÏÏÏÏ

PLL

RCLA

A

ÏÏÏÏÏÏ

PLL

RCLA

B

ÏÏÏÏÏÏÏÏÏ

PLLB

A

8 MHz

SWITCH orCE PBAs

Row Lead Rack Any Rack in the same row

The CLTD is simply a distribution board. It may deliver a signal to up to 20 differentdestinations using of no special logic except for the logic necessary to detect the absence of

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a clock signal. If it detects such lack of signal, it lights up the LED on the board stiffener andsends an alarm to the rack alarm board which, in turn, sends it to Defence.

Figure 111 : CLTD board

INPUT

1

20

LED ON

ALARM

The RCLA board is, somehow, more complex. It collects the signals from the two distributionbuses, re–shapes the pulses and randomly selects one of the two signals. To ensure smoothswitching to the non–selected signal, when required, the RCLA aligns the two signals. Thisboard uses the selected clock signal as reference for an oscillator that, in an autonomousmanner, tracks it and produces the 8 MHz clock to be distributed to all the multiports andcontrol elements in the rack.

As you can see in the next figure, the RCLA may produce two alarms. When the secondalarm is produced, the RCLA outputs are blocked and it warns the other board for it not toreach the same block situation.

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Figure 112 : RCLA alarms

– There is not reference

– Difference between PLL outputand reference > treshold

– No PLL output

– Differencebetween selectand stand–bybranches > treshold

– Extreme correctionto the PLL

1

14

RCLA

A chain

B ChainOutput Blocking

Report to the pairPBA in the rack fornot blocking

Alarm 1 Alarm 2To the Alarm PBA

Chain A toneinput lost

Chain B clockinput lost

Clock output lost

Chain A clockinput lost

Chain B toneinput lost

Chain selection: on(B) – off(A)

The RCLA PBA have three LEDs with the meaning showed in previous figure.

Every multiport or control element receives the two clock signals from the two RCLAs in itsrack and, in turn selects one of them randomly and, using it as reference for an oscillator,regenerates the 8 MHz clock necessary for the board operation. As before, if the selectedsignal is not received, the selector will switch to receive the other one.

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Figure 113 : Clock distribution into the rack

141

RCLA

141

RCLA

Two RCLA ofsub–rack

MCUA2 MHz 4 MHz 8 MHzSending toanother PBAin the module

Aleatory selection

The tones are generated by the DSGA board. This board contains the physical interfacebetween the OBC and the RCCA board, and the control element processor. Therefore,without this board, the ’clock’ part of the module could not communicate with the processor.The samples of the different exchange tones, as well as, the controls required for theirorderly reading and transmission through the pre–fixed channel, are stored in a PROMlocated on the actual board.

The RCCA OBC writes the Time Of Day (TOD) into a DSGA register every 100 ms., for itstransmission through two fixed channels.

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Figure 114 : Tone and Time of day (’TOD’) generation

10 2 3 4 31Tone Link PCM

Tone 1 SamplesTone 2 SamplesTime of Day

RCCA

OBC

Time of day

Samplesand

control+

DSGA MCUB

DISTRIBUTION

Register

OBC Bus

time indication

Microprocessor

RAM

PROM

The tones are subsequently distributed in parallel with the clock signals via the CLTD andRCLA boards. Every control element receives the two tones through its TI port 5 and canchoose the appropriate channel of any of the two receivers, to send the required tonethrough any of the channels of the transmitter ports in the TI.

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Figure 115 : Tone distributionDSGA

MCUB

CLTD

CLTD

CLTD

RCLA

Row Header Rack Any Rack in the same row

TI

1

20

DSGA

MCUB

CLTD

TI

1

20

1

1

20

20 Clock

1

6

RCLA

Clock

1

6

5

TI

MCUA

Clock Regeneration

C&T MODULES

The TSAB (Test Signal Analyzer board) is connected to the free MCUB port (3) towards themodule side. This board performs the same test analysis functions as the signal processorcontained in the TAUC board. The TSAB is implemented in the cases where the TAUC isnot; for example, in toll exchanges where it might be necessary to perform some measuringalgorithm concerning tones or announcements.

Figure 116 : TSAB location

CLOCK & TONES

MICROPROCESSOR

1

3

MCUB

TSAB

DSP

PROM RAM

S / PÌÌÌÌÌÌÌÌ


ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌ

ch 1

ch 1

The MCUB processor is related to the signal processor in the TSAB through readings andwritings from/to a RAM. This RAM will also be used to load the program to be executed by

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the DSP if it is not in the PROM. The data, signal samples, go through channel 1 of the PCMlink that connects the two boards, the TSAB and the MCUB.

The C&T modules are always equipped in the JF rack at the fixed 001D and 001C networkaddresses. The CLTDs used for the distribution towards the ”leading rack CLTDs”, arelocated in the same subrack as the CTMs. The first leading rack is the JF00 rack itself, soanother CLTD pair is provided within the rack.

Figure 117 : Clock and Tone modules in the JF rack

C&T ’A’ C&T ’B’ÌÌÌÌÌÌÌÌ

ÏÏÏÏÏÏÏÏ

ÓÓÓÓ

ÌÌÌÌ

ÌÌÌÌ

ÏÏÏÏ

ÓÓÓÓ

ÌÌÌÌÌÌÌÌ

RACK JF00

CCLARCCB

DSGA

MCUB

TSAB

CLTD

ÌÌÌÌÌÌÌÌ

ÌÌÌÌ

RCLA RCLA

CLTD CLTD

TO OTHER RCLAs IN THE ROW

TO OTHER ROWHEADER RACK

2.3.7 Digital Integrated Announcement Module (DIAM)

The announcements module is used to send the different messages required to notify thecalling subscribers about certain situations such as, for example, that the called subscriber’s

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phone number has changed. This module will also be used to send the time, that is, the’talking’ clock.

The DIAM consists of a single board called Dynamic Integrated Announcements PBA(DIAA), whose memory can optionally be extended with the AMEA board.

The announcements are sent to the Clock & Tone Module to be distributed by the tone bus,if they are fixed announcements; or, through the network towards their destination if, theyare variable. The variable announcements, such as the message giving the new phonenumber of a called subscriber, are composed by the control element of the DIAM fromelementary ones.

Figure 118 : Announcements distribution

–Tone Distribution

MCUA

MCUAALCNs

ALCNs

5

ÌÌÌÌÌÌÌÌÏÏÏÏ

ÌÌÌÌÌÌ

ÏÏÏÏ

0 1 2 3 4 x y 31

time

tone–1

tone–2

ann–1

ann–2

Time and

Tones

Fixed Announc.

Varriable Announc.: New subscrber’s number

DIAA

RCCA

CCLA

DSGA

CLTD CLTD

RCLA

For the elaboration of the announcements, the DIAA contains a processor specialized insignal processing, a DSP; a Queue RAM, where the samples to be sent through eachchannel are stored as blocks; and the corresponding Queue RAM Controller, QRC, whichoperates similarly to the one seen in the DSPA. The control element is also located in thissame board.

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Figure 119 : DIA structure


DSP

AMEA PBA

Program RAM

Sample RAM (4 MB)

8086

PROMRAM

ch X

FIFO RAM

TI

!6 MBytes

DIAA PBA

With the configuration shown above, up to 524 seconds of announcement time may bestored in the DIAA and, up to 42 minutes if the AMEA is implemented.

2.3.8 Peripheral & Load Module (P&L)

The P&L module is responsible for all communication between the exchange control and theperipheral devices, and for the download of the microprocessors equipped in the system. Anexchange is always equipped with two P&L, working in active/standby mode.

Regarding its peripheral functions, the P&L modules handles the MMC system in order tocollect the operation commands and present their results to the operator using the VDU andprinter peripherals. It also controls the access to the mass storage peripherals like tape,magnetic and optical disk, which contain the programs and data of all the CEs in theexchange.

Furthermore, the P&L module is responsible for loading the different exchange CEs duringthe initial exchange load or later individual reloads.

Due to the importance of this module functions, it is always duplicated and the pair worksin ACTIVE/STANDBY mode. In this way there is always one working, the other being ready(updated memory) and waiting to take over if the former one fails. Both P&L modules areconnected to fixed network addresses: 000C and 000D.

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Therefore, when any control element receives the power (power–on), or it has received amessage from maintenance software forcing its reload, a BOOTSTRAP program (stored inPROM) will be started. This program sends messages requesting a reload to both P&LTCEs. One P&L module replies to the requesting CE and reads the software packagesrelated to that CE from disk, sending it, through the network, to the starting module.

Figure 120 : CE down loading

ÌÌÌÌ

ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ

P & L

P & L

Control Element

DSN

MicroPROM

RAM

ÏÏÏÏ

A

B

ACTIVE

STAND BY

Reply and

Software Loading

Load Bid

Request

Besides the tasks related to the load of the software, the P&L module is in charge of thefollowing functions:

– Coordinate the maintenance actions and manage the tests started as consequenceof a corrective or preventive maintenance action.

– Handle the Man–Machine Communication system, in order to receive operationcommands and present their results.

– Control the mass storage peripherals for the performance of the reload, the load ofoverlay programs, the charging data collection, etc. These peripherals are: tapes,magnetic disks and optical disks which will replace the tapes in the future.

– Handle and coordinate the system extensions.

– ...

The structure of the P&L module is shown in the following figure.

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Figure 121 : P&L board structure

Inputs

16 alarms

fire,intrusion,..

DPTC

active

urgentalarm

non urgent

alarm

20

lamps

CLMA

MCUB

alam readings/lamp commands

ÏÏÏÏÏÏ

8 MB

RAM80386

MultimasterBus

localRAM

ROM

serialchans SCSI

ctrller

80186

sharedmemory

request andgrant lines

MMCA (optional)

DMCA

FIFO

80186RAM

PROM

four more devices

Magnetic

Disk

Optical

Disk

Adapt Formater

TAPE

SCSI

Bus

Up to 8SCSI devices

CH 16

The module is composed of the control element (MCUB), DMCA board (Direct MemoryControllers), the CLMA (Central alarm PBA) and, optionally, the MMCA (Man–MachineController).

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The MCUB, as the control element, can handle up to eight mass storage peripherals with a

standard interface called SCSI (Small Computer System Interface) and with the supportof the DMCA for the performance of the purely mechanical tasks. The devices may be eithermagnetic or optical disks, or magnetic tapes with their corresponding formatters andadapters to the SCSI. The MCUB can also handle two asynchronous terminals or up to fourof them if one MMCA extension board is implemented. A maximum of two MMCAs can beequipped per P&L module, allowing the connection of eight more terminals, or else theterminals may be connected in a ’shared’ mode.

Figure 122 : Simplex configuration

DMCA A DMCA B

MMCA A MMCA B

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Figure 123 : Duplex Configuration

DMCA A DMCA B

MMCA A MMCA B

Request line

Request line

4

4

The figure above shows how to connect two MMCAs with four shared terminals. Althoughthe diagram shows the connections of only two MMCAs, when four of them are equipped,the connections are done in the exact same way.When a MMCA is going to work with oneterminal, it activates the request line so that the terminal will be ’captured’ by that side (thatMMCA) and the other side will not be able to close the access relays for that terminal.

The CLMA communicates with the MCUB through channel 16 messages that are collectedby a DPTC interface. This message collection is done in a way similar to that in the ALCN(line board). When the MCUB sends a message to the CLMA, four bytes are written into amemory that is later emptied into a control register. This register handles the periodicerasure of a counter that, when not preset, produces an alarm: Dual failure . This alarm iswired together with the alarm of the other module so that both CLMAs must failsimultaneously before the alarm signal is sent to the Main Panel for Alarms (MPA).

The CLMA LEDs have the following meaning:

1. active board 2. urgent alarm3. non–urgent alarm.

The MCUB can read up to 16 floor alarms (fire, intrusion, etc.) and the status of four keys,from the main panel (MPA).

Optionally a second CLMA can be connected which will simply receive and light up morealarms while the ’dual failure’ handling mechanism is deactivated.

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The two P&L modules, as well as the two CTMs, are located in the same rack: the JF00rack.

Figure 124 : P&L into the rack JF00









DMCA

MCUB

Access switch

1st and 2nd (opt)

MMCA

1st and 2nd (opt)

CLMA

airbaffle

2.3.9 ISDN Subscriber Module (ISM)

The ISDN Subscriber Module is prepared to receive a ’U–interface’ . This interface providesfor the digital transmission and reception to/from the subscriber of two 64 Kb/s channels for

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speech or data, and one 16 Kb/s channel for signalling or X.25 packets, using the same pairof wires of the actual analogue subscribers.

Figure 125 : Basic access diagram

NT

TA

a

b

subscriber loop

2

2

S

interface

TA

PC

4

B B D

8 8 4

ISDNSubscriberModule

(two copper wires)

Four wires A1000 S12 EXCHANGE

Up to eight terminals can be connected to the subscriber side. They will be connecteddirectly if they are ISDN terminals, or through a Terminal Adapter (TA) in the case ofnon–ISDN terminals.

To allow for the transmission of the 144 Kb/s (the two B plus the D channels) through thepair of wires, the line codes of three or four levels are used. These line codes are the’4B/3T’, which sends a ternary symbol representing a four–bit pattern; or the ’2B/1Q’, whichsends a quaternary symbol representing a two–bit pattern. These line codes reduce thespeed to 3/4 or 1/2 of the original speed, depending on the code used. The subscribermodule will be in charge converting this code to binary.

Besides the code adaptation, the subscriber module must also separate the twotransmission directions and cancel the incoming echo.

The line signalling of the eight possible terminals consists of the transmission of messagesthrough the D channel. Therefore, the eight terminals must ’compete’ for the use of theavailable 16 Kb/s available. Conceptually, these messages are similar to the N7 messagesbetween exchanges. A link level is used to protect the transmission of these messages, i.e.

the messages are sent in HDLC (High–level Data Link Controller) frames of a particular

format called LAPD (Link Access Procedure D). This format allows the transmission orreception of messages to/from more than one terminal since it contains a terminal identityfield.

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Figure 126 : Signalling levels

ÌÌÌÌÌÌ

D

D

Dialling

Terminal + TA

SETUP

Type of info

Called Number

Calling number

Facilities

speech

audio 3.1

digital

flag CRC DATA control address flag

Level 3 information

Level 2 Frame

Call Control

Level 3

Internal dialogueISDN SubscriberModule

– Terminal identity (1/8): TEI– Service Type (Signalling or packet): SAPI

Frame type:establishment orinformation orreceiver ready oretc.

Level 2

The ISDN subscriber module is made up of eight ISTA/ISTB/ISTC boards (ISDN SubscriberTermination type A PBA). Each board handles eight subscribers, so the ISM provides accessto a total of 64 ISDN subscribers. In the same way as for the analogue subscriber module,every two ISMs are connected in crossover (X–OVER).

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Figure 127 : ISM PBA composition

1

8ISTA/B/C

MCUB

1

8ISTA/B/C

TO THE OTHER CE

(Cross–Over)

a

b

8 x 8 = 64 Subscriber loops

1. The ISTA board, which is used when the U–interface uses the 4B/3T coding,almost contains the same circuits as the DTRI board used in the N7 trunk module. Thus, wehave the ILC for the partial handling of level 2, and the OBCI as the local space–timeswitching element. These circuits plus the UIC (U–Interface Controller), which performs theabove–described functions of code adaptation and echo cancellation, make up the ISTAboard (see figure 128).

Each UIC receives clock signals (channel time strobe) that it uses to order its output.

Four ILCs, each with two HDLC frame handlers, are programmed by the OBC to check ifthere are frames, delimited by flags, in the eight possible D channels: ILC1 will check thefirst D channel and the second D channel, and so on. When one HDLC in one ILC finds aframe, it puts it in memory and notifies the OBC. The OBC then analyzes the level 2 fieldsand eventually responds by extracting the signalling message and sending it, through theOBCI, to the control element (MCUB). At the request of the CE, the OBC drives theswitching of the speech channel in the OBCI.

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Figure 128 : ISTA structureOBCI

sending

ILC ILC ILC ILC

1 2 3 4

found

frame

found

frame

RAM

PROM

OBC

– Level 2 Analysis

–Level 3 extraction

– Ordering of

switching the

speech channels

OBCI switching

B1 B2 B3 B4 ..............

1 2 3 4 5 6 7 8 ...............32

V* Interface

0

7

4B/3T

T/4B

0

7

– Echo cancellation

– Decodig to binary

UICs

clock

to CE

ch1: B1

D1 D2

2. For the 2B/1Q line code, a similar board, differing only in respect of the UIC LSI,has been designed. This board is named ISTB.

3. Recently, a new board has been developed : the ISTC, which can be used forboth 4B/3T and 2B/1Q coding.

This card exists in different hardware variants

ISTC–T –—–> 4B3T coding for the U–interface (replacing the ISTA)

ISTC–Q –—–> 2B1Q coding for the U–interface (replacing the ISTB)

ISTC(+)–T –—–> 4B3T coding for the U–interface (replacing the ISTA)

ISTC(+)–B –—–> 2B1Q coding for the U–interface (replacing the ISTB)

(ISTC(+) supports HDLC tunnel.)

Compared to its predecessors, this ISTC is an enhanced ISDN board in terms of use of stateof the art technology leading to increased performance. In line with cost control, technicalimprovements are introduced: technological progress, corrections needed to meet changedstandards and functionality.

To cope wuth these new features, memory size is increased allowing more OBC–code andsoftware resources, but also the ”double memory” feature for future support of ’softwarereplacement with Zero Outage Time (ZOT) and Stable Call Preservation (SCP)’.

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The functional enhancements are

1) compliance to newest standards of ETSI

2) Support of Zero Outage Time (ZOT) and Stable Call Preservation (SCP)

3) HW Identification

4) HDLC Frame concentration function for B–channelsBecause of ISDN subscriber demands for internet, there is an increasing demand forHDLC frame handling no longer only on D–channels but as well on B–channels. Up tonow we handled packet traffic on B–channels circuit switched. This strategy must beextended because of internet calls are characterized by other/new traffic values. Thoseare

– in average a much longer call holding time a low average data rate (comparedto 2*B–channel bandwidth)

– an unbalanced average data rate from subscriber to network compared to fromnetwork to subscriber

– traffic peaks using the complete bandwidth to one subscriber

Because of those characteristics a frame concentration function shall be implemented,which allows concentration of packet traffic from several (amount is traffic dependent )B–channel to a single 64 Kbit/s channel on a cluster link. In average a concentrationfactor of 8 is envisaged.

Therefore each B–channel shall be terminated by a HDLC controller.

5) HDLC Tunnels and Cluster Bus Contention MechanismThe basic characteristic of a HDLC–tunnel is, that it provides between two modules ofA1000–S12 and across the DSN a permanently established 64 Kbit/s channel, which isterminated on both ends by a hardware HDLC controller.

Examplary an HDLC–tunnel can be accessed on the cluster bus of subscriber moduleby multiple (OBC–)processors (sharing the same channels), while it ends on the otherside in a single processor, which handles the concentrated traffic.

2.3.10 Mixed Subscriber Module (MSM)

Besides the Analogue Subscriber Module (ASM) and ISDN Subscriber Module, a third typeof subscriber module exists, which consists of a MCUB, and a number of ALCx and ISTx,allowing to connect to the same module a number of analogue and/or ISDN subscribers.

2.3.11 ISDN Trunk Module (ITM)

The subscriber access previously studied provides only two channels for speech/data at 64Kb/s and is called basic access. For high traffic subscribers such as an ISDN PABX, a

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different access, called primary access, is used. This access is based on a digital32–channel PCM link where one channel is reserved for the signalling of all the others.

Figure 129 : Primary Rate Access

31 X 16 0

SIGNALLING CHANNEL:

– Sending of point to point LAPD framesTEI = 0, SAPI= signallingwith signalling messages related to therest of the channels

In the A1000 S12 system, the module that receives such interface is the ITM. This module ismade up of a DTRI and an MCUB board, identical to those used in the N7 trunk module butwith different software. The ITM boards contain the software required to handle the ISDNlevels two and three.

Figure 130 : IPTM functions in PRA

TRAC

ILC

RAMOBC

386

PROM

CH X

CH 16

CH Y

CH X

SIGNALLINGMESSAGES

LEVEL 2 ANALYSIS

LAP–D

FRAMES

– HDB3 / BIN

– RETIMING

– FRAME ALIGNEMENTTREATMENT

– 8 / 16 BITS

LEVEL 3

TREATMENT

DTRI

MCUB

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2.3.12 The Data Link Module (DLM)

The A1000 S12 modules do not support modem connections (e.g: HCCM, IPTM, ...) Whenan analogue modem connection is required (e.g: connections towards an Electronic Data

Processing Centre (EDPC) through the Packet Switching Network (PSN), analogue N7connections, ...), an additional module is used: the Data Link Module.

The Nr7 message is prepared in the HCCM (or IPTM) module. From there it is transmittedtowards the DLM module which is connected to the modem using a V24 functional interface.

The DLM is composed of two PBAs: the MCUA/E and the MIRB. The MCUA/E contains theCE and the TI. The MIRB PBA is responsible for the physical data transmission to theEDPC.

Figure 131 : Analogue N7 connectionÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌ

ACE

DATA TO BE SENT

IPTM X.25

LAPB

X.25 PACKET

DTE1

DTE4

DCEPSN

X.25 PKT

GENERATION

MCUA/E MIRB

DLM

modem

modem

modem

2.3.13 EPM: Extended Peripheral Module

Extended Peripheral Module (EPM) provides the means of interworking between S12 andLocal Area Network (LAN), which is combined with TCP/IP on transport and network layerand 10 BaseT Ethernet on data link layer and physical layer.

As a node in a local area network (LAN) which uses 10 BaseT Ethernet as a backbone,EPM allows S12 to interconnect with all nodes of a LAN by means of TCP/IP protocol. Theadvantages of developing EPM module is that :

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� By using TCP/IP functions in EPM, as an interface between S12 and LAN, applicationprograms can be developed on the WSs/PCs

� Because of the powerful tools and libraries to design graphic user interface (GUI) with aworkstation, such as X windows, MOTIF, Sunview, etc. S12 programmers can developuser friendlier interfaces

� An alternate for S12 to provide other I/O channel devices. For example, the networkmeasurement data or the charging data can be sent directly to a workstation or a PCdisk. I

� High speed transmission channel toward PC/WS, compared with RS232.

The EPM module will be implemented as a system ACE in phase 1. More than one EPMmodule is possible in one exchange which act as nodes for different LANs. The number ofEPM modules depends on the traffic load of various applications. The maximun traffic loadper EPM will be evaluated during testing.

An interesting board in the EPM is the LAN Module Controller (LMCA) PBA. This PBAinterfaces to a twisted pair ETHERNET LAN (10baseT) external device or HUB. It will beused in the S12 EPM for LAN applications. The PBA–LMCA environment in the S12 systemis presented in the next figure.

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Figure 132 : LMCA

TERMINAL

INTERFACE

BUFFER

MEMORY

SERIAL INTERFACE

PROCESSOR

DSNCLUSTER

MMB/HSB

TERMINAL

INTERFACE

PART

PROCESSOR

PART

LMCA

DEMUX

ETHERNET

LANI/F

The processor (D229) is a 32–bit Intel 80386 compatible microprocessor

The memory includes up to 8 Mbytes of on–board memory.

The ETHERNET LAN interface circuits comprise the following areas:

� Serial network interface controller (SNIC). The serial network interface used inPBA–LMCA is NS DP83902 (Serial Network Interface Controller, SNIC) D1701. Itprovides a comprehensive single chip solution for 10BASE–T IEEE 802.3 networks.

� Address ID PROM. This is used to store a unique network address.

� Buffer memory. The buffer memory (D1601,D1602) is used for temporary storage ofreceive and transmit packets.

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� I/O ports . The I/O ports are the buffer which interface between processor and SNIC.

� 16/32 Bit data Bus buffer. The data bus buffers (D1604 and D1607 or D1613 andD1616) are used for 16–bit bidirection data transfer.

� LED Indicator. These LEDs are used to indicate the status of LAN chip.

2.3.14 ISDN Remote Subscriber Unit (IRSU)ISDN RSU Interface Module (IRIM)

The IRSU is a mixed analog/ISDN telephone line concentrator, designed for use in both ruraland urban environments. Subscribers connected to an IRSU receive the same services andfacilities as if they were connected to a subscriber module.

An IRSU allows the remote connection of up to 976 analogue subscribers, 480 ISDNsubscribers or a combination. The proportion of analogue and ISDN can be varied to meetchanging requirements, using the ratio of one ISDN to two analogue subscribers. SeveralIRSUs can be connected to an A1000 S12 exchange, which is called the multidropconfigurations. This multidrop configuration consists of a maximum of eight IRSUs, providingaccess to up to 1024 analogue or 512 ISDN subscribers or a combination. The interfacemodule used in the A1000 S12 exchanges is the so called IRIM. The actual interface isrealised with digital links.

Figure 133 : IRSU point to point configurationIRSU

IRIMPCM LINKS

A1000S12

Up to976 Analogue

or480 ISDNsubscriber

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Figure 134 : Multidrop configuration

1 2 8

IRSU

IRIM

IRSUIRSU

UP TO 1024 OR 512

The multidrop configuration can be easily extended till the maximum number of 8 IRSUs byadding new IRSUs. The dialogue between the IRIM and each IRSU in the multidrop is basedon the control of a series of multiplexers , named K1 and K2. These multiplexers makepossible the isolation of the IRSU (e.g. when the feeding fails), or the closing of the loopfrom one IRSU on, as well as, the option to insert messages or not into channel 16, or lettingthe messages addressed to another IRSU or to the IRIM pass through.

Figure 135 : Multiplexers in the multidrop configuration

CONTROL

LAST

IRSU

IRSU 8 IRSU 1

IRIM

ÌÌÌÌÌÌÌÌ

MIO DATA

K2 (LOOP)

K1 (BY PASS)

CH 16

ALL

CHANNELS

CH 16LOOP

CH 16

K2TOKEN

IRSU TO IRIMIRIM TO IRSU

IRSU

ADDRESS

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Let’s suppose that the K1 and K2 muxes are in the position shown in the figure. The channel16 loop mux is in the position that lets channel 16 go forward to be transmitted by the IRIM.After the complete loop channel 16 will come back to this mux.

Using the token and the address field in the signalling frames, the IRIM starts the procedureto exchange data in the multidrop. The token is passed in a circular way and only the IRSUwhich has the token can send CCS Nr7 messages to the IRIM and at the same time, receiveMSUs from the IRIM.

Both the IRSU and the IRIM consist of several specific boards, mainly the DTRH or thedigital trunk,the CALC for the simplified clock and alarms; the control element board (MCUB)in the IRIM, the subscriber PBAs (ALCN and /or ISTA/B) in the IRSU, with the addition of theRNGF and the TAUC PBAs for ringing and testing functions. Furthermore, the optionalboards for transmission, the TMIA and LPFA, can be added.

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Figure 136 : IRSU structure at PBA level

TRACOBCI

TRAC

OBCI

OBC

TI

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ

MCUB MCUB

DTRHDTRH

DTRH

DTRHCALC

CALC

TMIA

32 ALCN / ISTA + RNGF + TAUC

32 ALCN / ISTA + RINGF

HIGH LINES

LOW LINES

K1

K2

TMIA

LAST IRSU

AMPLIFIERS

STANDARD PCM TANSMITION EQUIPMENT

TWO PCM LINKS

X_OVER

ILCOBC

OBCITRAC

ILCOBC

TRAC

OBC

OBCI

TI

IRIM

CLOCK

CLOCK

OBC

OBC

The DTRH board has the following structure:

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Figure 137 : DTRH PBA structure

ILC

USART 256 K 1 KOBC80386

RAMPROM

DTRHV24 TEST INTERFACE

2 Mb/s

CH 16

CH 16

OBCI

CH 1

CH 1

LOOPCONTROL

First we find the same physical interface (transformers and loop) used in the DTUA and theDTRI and also the same trunk interface circuit for HDB3 binary conversion, retiming andframe alignment handling. Then we find a PCM link at 4 Mb/s (16 bits/channel) that goes tothe OBCI. In the OBCI, channel 16 is switched towards the ILC to monitor the messages.Also the multiplexer is shown via which the CH16 loop can be opened or closed (seeexplanation before).

On the other hand, the CALC board (Clock & Alarms) contains a simplified clock circuit thatproduces the internal clock, using the 2 Mb/s clocks regenerated from the PCM links. Thesereference clocks are sent by the clock regeneration circuit contained in the physical interfacecircuit of each DTRH. This board is duplicated in each IRSU. Each CALC controls the clockto be selected (choice between their own or the partner clock). In that way, only one singleclock is distributed. In each CALC, the selected clock is supervised, and a switching isperformed in case of failure.

The CALC also contains the logic required for the handling of the alarms and the control ofthe TMIA loops.

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An 8031 processor collects the IRSU alarms (converters, etc.), writes alarm indicators, andreports changes to SW in the host. The processor handles the TMIA loops, through a’programmable interface’ contained in a chip, and also controls the ring current and itsassignment to one of the board by closing the appropriate relays.

It must be clearly understood that, with this architecture, the call and the PCM link channelsused are under the control of the IRIM control elements (MCUBs). A possible call scenariocould then be as follows:

Figure 138 : Call Handling simplified scenario for IRSUs

OBCI

OBC

OBCI

OBC

OBCI

OBC

OBCI

OBC

DPTC

ALCN

DTRH MCUBDTRH

DTRH DTRH

1

5

2

2

3

3

CH 16

CH 16

4

4

ÌÌ

ÌÌÌÌ

X Y

TONES

1. The related DPTC line collects the hook off event.

2. This event is read by both OBCs of the two DTRH PBAs

3. Using the token protocol, both OBCs send a message containing the event to the mate OBCs in the IRIMs

4. These OBCs, knowing from the message content that the related line is a high one, transfer the event to the high MCUB (if it is on line).

5. The MCUB software selects a speech channel (’Y’) in the MCUB DTRH link, and another one (’X’) is selected in the PCM link towards the IRSU. In the DTRH, both channels are joined, allowing the tones to reach the IRSUs over this path.The IRSU is informed of this speech channel assignment by a channel 16 message.The Call Control software continues, using this strategy, with a message flowIRSU–IRIM, and vice versa, to perform the different Call Control decisions in the hostexchange.

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To increase the traffic capacity of the IRSU multidrop, calls between subscribers connectedto the same IRSU are switched internally (within the IRSU), whereas calls betweensubscribers connected to different IRSUs on the same multidrop are switched locally, usingonly a channel of the PCM link in each direction for each call.

In case the communication between the IRSU and the host exchange is lost, the IRSU willbe switched to stand–alone mode. Functions to be performed depend on whether anoptional Emergency Call Feature (EFC) is equipped or not. If so, up to 23 stable callsbetween subscribers connected to the same IRSU can be handled.

If required by the traffic, the number of available PCM channels can be doubled byduplicating the number of PCM links. To do so, the DTRF board is used instead of the DTRHas the former has two PCM links.

Figure 139 : DTRF PBA structure

LINK 1

LINK 2

TRAC

TRAC

OBCI

OBCI

LSCM

ILC

OBCRAM

DTRF

With this, the IRSU structure would be:

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Figure 140 : IRSU structure using DTRF PBAs

ALCN/ISTA

ALCN/ISTA

CALC

CALC

DTRF

DTRF DTRF

DTRF MCUB

MCUB

IRSU

IRIM

The IRSU contains maximum 61 ALCNs or 60 ISTAs, as the ALCN boards may besubstituted by ISTA boards (some exceptions for some positions). In case of maximumcapacity (976 analogue lines or 480 ISDN subscribers), one IRSU is placed in half a JR03rack, occupying three subframes (shelves). One rack may hold up to two IRSUs, thetransmission equipment being installed separately.

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Figure 141 : IRSU Rack distribution and IRSU alternatives

480

240

112

40

24

32 64 96 256 512 976

ANALOG LINES

ISDN LINES

FRAME WITH 3 SHELVES

FRAME WITH 2 SHELVES

FRAME WITH1 SHELF OR

CABINET

AIR BAFFLE

ALCN

ÏÏÏÏ

ÌÌÌÌ

ÓÓÓÓ

ÓÓÓÓ

ÌÌÌÌ

ÏÏÏÏ

ÑÑÑÑ

1 16 161

1 14 151ÑÑÑ

ÏÏÏÌÌÌÌÓÓÓ

TAUC

RNGF

DTR M/F

CALC

CONVERTERS

– TRANSMISSION EQUIPMENT

– BATTERIES

The TMIA and CALC boards have some LEDs and keys on their stiffener that have thefollowing meaning:Remark: Going signal = from previous IRSU and Back signal = from next IRSU.

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Figure 142 : CALC and TMIA PBAs

Urgent Alarm

Sanity Timer Expired

Non Urgent Alarm

”By pass” mux switch

CALC

Pass done

Going signal lost

Back signal lost

Loop mux switch

Loop done

Loop bypass activated

Loss of synchronisation

2.4 Remote Terminal Sub Unit (RTSU)

In addition to IRSUs, and in particular for larger subscriber clusters, it is possible to opticallyremote entire parts of an Alcatel 1000 S12 exchange, including some subscriber modulesand their access switches to the Digital Switching Network. These segregated parts arenamed RTSU (Remote Terminal Sub Units), which can be equipped with one or moreanalogue or ISDN TSUs – Terminal Sub Units–, linked to the host by means of optical fiber.

As explained in previous chapters, every subscriber TSU is composed of up to eightanalogue or ISDN modules connected to ports 0 to 7 in two Access Switches. Furthermodules (Auxiliary Control Elements, P&L TCE, C&T TCE, etc.) can be connected to ports12 to 15. The Access Switches use ports 8 to 11 to connect to the group switches in planes0, 1, and optionally 2, and 3. The figure shows an example of these TSUs for a four–planeDSN.

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Figure 143 : ’TSU structure’

MODULE 0ACCESS

SWITCH

ACCESS

SWITCH

89101112

13

1415

89101112

131415

0

1

7

0

1

7

ACCESS

SWITCH

89101112

13

1415

1

7

ACCESS

SWITCH

89101112

13

1415

1

7

ACCESS

SWITCH

89101112

13

1415

1

7

GROUP

SWITCH

89101112

13

1415

N

PLANES

3

2

1

0

SUBSCRIBER

MODULE 1

SUBSCRIBER

MODULE 7

SUBSCRIBER

MODULE

NOT SUBSCRIBER

MODULE

NOT SUBSCRIBER

MODULE

NOT SUBSCRIBER

MODULE

NOT SUBSCRIBER

N+4

N

N

N

If, as in the above TSU example, subscribers are located in a remote area, an RTSU can beused to provide telephone access to these subscribers. The figure represents a scheme ofthat possible configuration.

Figure 144 : Remote Terminal Sub Unit

MODULE 0

ACCESSSWITCH 1

7

1

7

1

7

GROUPSWITCH

REMOTE AREA HOST SITE

Optical FiberMODULE 1

MODULE 7

ACCESSSWITCH

0

1

2

3

The concept of RTSU –remote subscribers and optical links– makes possible to spreadsubscriber lines of an exchange to be spread over a vast area, entailing copper pair costsaving and allowing long distances from the subscriber cluster to the host exchange. Allthese remote subscribers are offered the same functionality as the local ones.

In case of isolation, due to a link failure, the RTSU must make it possible to set up internalcalls. Therefore, for MF analysis purposes, some SCMs are equipped in the RTSU. Another

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feature of the RTSU is the possibility of connecting a VDU to it for on–site Operation andMaintenance purposes.

The link to the host is realised by extending all the 4 Mbps PCM links between the accessswitch and the group switch in the first stage of the Digital Switching Network. Every AccessSwitch offers a 4 Mbps link to every equipped plane in the host. These links are multiplexedat both ends using one or more multiplexers, which are implemented as standard Alcatel1000 S12 PBAs. These multiplexers can combine up to eight 4 Mbps PCM links in a 34Mbps CCITT G.703 link and a binary interface to an EOC (electro–optical coupler). ThisEOC can also be provided in a standard Alcatel 1000 S12 PBA.

The transmission system also gathers the clock and tone provision in the cluster from thehost. The tone link is sent as a 4 Mbps PCM link, and the clock is extracted from the 34Mbps link by the multiplexer. This clock is the reference used by the SCLA –SimplifiedCLock version A– PBA, to produce and distribute the internal clock in the RTSU. This boardincludes a PLL circuit that is able to provide a clock signal in the case of a link failure. ThisSCLA board plus the control board is named the RTSU Emergency Clock & Tone Module–RECM–.

The figure shows an RTSU architecture for one TSU with 1024 analogue lines – approx.0.15 Erlang per line–, or 512 ISDN subscribers. Two optical lines –therefore twomultiplexers– are always used for reliability reasons.

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Figure 145 : RTSU architecture and connection

ASM/ISMSWITCH

ASM/ISM

ASM/ISM

1

2

8

ACCESS

N

SWITCHACCESS

N+4

SCM

SCM (opt)

RECM

1

1

2

M

U

X

M

U

X

E

O

C

C&T

Distribution

Tone

Clock

ACCESS

SWITCH

89101112

13

1415

1

7

ACCESS

SWITCH

89101112

13

1415

1

7

ACCESS

SWITCH

89101112

13

1415

1

7

GROUP

SWITCH

89101112

13

1415

N

N+4

PLANES

3

2

1

0

M

U

X

M

U

X

N

N

N

ToneClock

Optical

Fiber

0

1

7

0

7

1

8

1112

15

8

1112

15

E

C

O

E

O

C

E

O

C

For more than one TSU segregation –multi–RTSU–, it is not necessary to provide eachTSUwith its own multiplexer (one or two). It is possible to take advantage of the eight inputs ofthe multiplexer to mix the links of each TSU. The second example on the next page shows amulti RTSU example which supports three TSU accesses using four multiplexers.

In these multi–RTSU configurations, where three or more 34 Mbps connections are needed,it is generally more economical to multiplex the links (G.703 outlet) to a higher order –e.g.140 Mbps– using a commercial multiplexer and EOC.

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Figure 146 : Multi–RTSU example

AccessSwitch

AccessSwitch

TSU 0

AccessSwitch

AccessSwitch

TSU 1

AccessSwitch

AccessSwitch

TSU 2

M

U

x

M

U

x

M

U

x

M

U

x

M

U

x

4 Mbps

34 Mbps

140 Mbps

The RTSU is implemented in the JA02 rack. This rack, fully equipped, supports up to 12subscriber modules (ASM or ISM ones), 3 service modules, 6 RTSU Emergency C&Tmodules, 6 multiplexers, and up to 6 Access Switches. The EOC PBAs can be equipped inthe air baffle area of the rack. In the host, the RTSU optical links are connected to a set ofEOCs and multiplexers located in the rack type JJ02. This rack has the same configurationas the JJ00 rack (see the Exchange configuration chapter), but includes a number of slotsfor the multiplexer PBAs.

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Figure 147 : JA02 Rack

AIR BAFFLE

ALCN / ISTX

1 8

ÌÌÌ

ÏÏÏ

ÏÏÏ

ÏÏÏ

1 8

ÌÌÌ

ÏÏÏ

ÏÏÏÏÏÏ

ÏÏÏ

1 8

ÌÌÌÌÌÌ

ÓÓÓÓÓÓ

ÓÓÓ

1 8

ÌÌÌ

1 8

ÌÌÌÌ

ÏÏÏÏ

ÏÏÏÏ

ÏÏÏÏ

1 8

ÌÌÌÌ

ÏÏÏÏ

ÏÏÏÏÏÏÏÏ

ÏÏÏÏ

1 8

ÌÌÌÌ

ÏÏÏÏ

ÏÏÏÏ

ÏÏÏÏ

1 8

ÌÌÌÌÌÌÌÌ

ÏÏÏÏ

ÏÏÏÏ

ÏÏÏÏ

1 8

ÌÌÌÌ

1 8

ÌÌÌÌÌÌÌÌ

1 8

ÌÌÌÌÌÌÌÌ

ÓÓÓÓÓÓÓÓ

ÓÓÓÓ

1 8

ÌÌÌÌ

ÓÓÓÓ

ÓÓÓÓÓÓÓÓ

ÌÌÌÌÌÌÌÌ

Subscriber

Module

MCUB

ÓÓÓÓÓÓÓÓ

ÓÓÓÓ

SCM

ÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏ

Multiplexer

RECM

SWCH

This rack is used to equip three different sizes of TSU. For traffic reasons, an exchangeshould not have a mixture of different RTSU sizes, except in those cases where RTSUshave not reached their final size to allow for future extensions. The quantity of ASM/ISM perTSU is defined by the traffic per line according to the following list:

� Low traffic RTSU (less than 0.151 Erlang/Line): 8 Subscriber modules/TSU

� Medium traffic RTSU (less than 0.201 Erlang/Line):6 Subscriber modules/TSU

� High traffic RTSU (less than 0.275 Erlang/Line):4 Subscriber modules/TSU.According to this ratios, the maximum capacity of the JA02 rack is of three –hightraffic–TSUs .

The following figures contain two schematics of rack and RTSU configurations for high andlow traffic TSUs. The first one shows a three high traffic TSU RTSU configuration –twelvesubscriber modules–. The second one shows, a three low traffic TSU RTSU –24 subscribermodule–. In the second case, two racks JA02 are needed.

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Figure 148 : RTSU Rack for High Traffic TSU

AIR BAFFLE

Module 2TSU 2

Module 3TSU 2

Module 1TSU 2

Module 0TSU 2

Module 3TSU 1

Module 2TSU 1

Module 1TSU 1

Module 3TSU 0

Module 1TSU 0

Module 0TSU 0

Module 2TSU 0

Module 0TSU 1

Figure 149 : RTSU rack configuration for Low Traffic TSU

AIR BAFFLE

Module 2TSU 1

Module 3TSU 1

Module 1TSU 1

Module 0TSU 1

Module 7TSU 0

Module 6TSU 0

Module 5TSU 0

Module 3TSU 0

Module 1TSU 0

Module 0TSU 0

Module 2TSU 0

Module 4TSU 0

AIR BAFFLE

Module 6TSU 2

Module 7TSU 2

Module 5TSU 2

Module 4TSU 2

Module 3TSU 2

Module 2TSU 2

Module 1TSU 2

Module 7TSU 1

Module 5TSU 1

Module 4TSU 1

Module 6TSU 1

Module 0TSU 2

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3. A1000 S12 SOFTWARE

3.1 Functional subsystems

The Alcatel 1000 S12 software provides all the exchange services by managing the relevantcircuits. The main service is the call handling function, with a series of additional facilities(abbreviated address, three party, detailed billing, etc..). In addition, the software offers tothe administration a broad range of features intended for operation, administration, andmaintenance tasks.

This software is broken down into a series of subsystems by grouping common functions.Furthermore, by successively breaking down these functions they are grouped into areasand finally modules .

The software breaks down into six basic subsystems :

� Operating System

� Database

� Call Handling

� Telephonic support

� Maintenance

� Administration.

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Figure 150 : Software building blocks

MAINTENANCE

ADMINISTRATION

CALL

HANDLING

DATA

BASE

OPERATING

SYSTEM

TELEPHONIC

SUPPORT

Every subsystem breaks down into a series of software areas.

� The Operating System and the Data Base contain the following software areas:

– Operating System Nucleus

– Network Handler

– Input/Output

– Man Machine SW

– Load and initialization

– Clock, Tone and Calendar

– Data Base Management System

� The Telephonic Support subsystem is made up of:

– Telephonic Device and Signalling Adaptation

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– Signalling Handling

– Charging

– Remote Subscriber Unit

– Network Service Centre

– Packet Switching

– CCITT N7 Common Channel Signalling Message Transfer

� The Call Handling consists of the following areas:

– Call Handling and Facilities

– Call Service

� Maintenance covers the areas:

– Maintenance SW

– Status and Alarm SW

– Line and Trunk testing SW

– Test Signal Analyzer and Test Access Unit SW

� Finally, the Administration subsystems contains:

– Administration SW (Traffic and performance measurements)

– Extensions

At the lowest level are the software modules. The software areas are divided into modulesthat are completely independent of each other. These modules are called Finite MessageMachines (FMMs) and System Support Machines (SSMs) . The communication betweenFMMs is carried out through normalized data structures known as messages . Theinteraction between FMMs and SSMs is performed by means of procedure calls in the FMM––> SSM direction, and through messages in the SSM ––> FMM direction.

All these software modules are distributed over the different hardware modules. As can beseen in the figure, the software is distributed among the different modules. This distributionis not carried out in an arbitrary way, instead each module contains that part of the softwareit needs for its operation.

The support software (Operating System Nucleus, Network Handler, Data Base SW, and soon) is distributed over all CEs in the exchange.

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3.2 Software concepts

3.2.1 Finite Message Machine (FMM)

a. Definition and characteristics

An FMM is the basic software–building functional block and has the followingproperties:

– It can communicate with other FMMs but only through messages.

– From the outside, an FMM is a “black box”, i.e. its internal structure is not known tothe rest of the system. Its functional behavior is uniquely defined by the set ofmessages it sends and receives.

– It may be in one of several different states and transactions between these areallowed. A limited set of messages is defined for each state. After receiving amessage, the FMM may generate and transmit output messages and its state maychange.

Figure 151 : An FMM as a black box

FMM INTERFACE:

M1_ORIG M3_INFO_LDC M4_SLCT_CH&

M2_CH_INFO M5_ACT_CACO

M1_ORIG

M2_CH_INFO

M3_INFO_LDC

M4_SLCT_CHF M M

M5_ACT_CACO

b. Finite State Machine (FSM)

By definition, we know that an FMM may be in one of several states. The FMM mayemit one or more output messages and/or change from one state to another uponreceipt of a message. This state change mechanism brings us to the FINITE STATEMACHINE concept.

For a proper understanding of this concept, we will study the example shown in nextfigure. It shows how the FMM can receive messages A, B and C and, in turn, send

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messages D and E. The functional behavior of the FMM is completely defined when themessage reception and transmission sequence is known. The sequence in ourexample will be: For the FMM to send message D, it must first receive either messageA, or C and then B. To send message E, it must receive message B before A.

This FMM may be built with three states. Figure 152 shows the way the FMM works.The three states are:

– INIT:This state indicates that the FMM is waiting for message A, B or C. If it receivesmessage A, it sends message D and changes to the INIT state. If it receivesmessage B, it changes to the B_REC state. If it receives message C, it changes tothe C_REC state.

– B_REC:This state indicates that the FMM received message B and is now waiting to receivemessage A. When this message arrives, the FMM will send message E and go backto the INIT state.

– C_REC:This state indicates that the FMM received message C and is waiting to receivemessage B. When it arrives, the FMM will send message D and go back to the INITstate.

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Figure 152 : FSM structure

START FMM

INIT B_REC C_REC

INIT

STATE

WAITING

MESSAGES

BA C A B

D DESTATE

B_REC

STATE

INIT

STATE

C_REC

STATE

INIT

STATE

INIT

c. Types of FMMs

Before studying the different types of FMMs to be found in the system, we must firstdefine a term that is very important in all FMM executions : the PROCESS. An FMMconsists of a part that is pure code, called process definition , and another part withthe data, known as process data . The execution of a process definition with itsassociated process data is known as process .

Let us now study the different types of FMMs with the help of some practical examples.

– Monoprocess FMM

First, let us have a look at the FMM that analyzes the prefix. When executed, this FMMwill establish, among other things, the call destination, i.e. whether the call is local oroutgoing. The FMM will start its execution (process definition) using the data area(process data) at the moment it receives a request in the form of a message. When theexecution ends, the FMM will output a message and the data area will no longer beneeded for this request. When a new message arrives at the FMM, asking it to analyzeof a prefix, the same process definition will be executed again and the same data areawill be used. This means that a single data area is required for this type of FMM. These

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FMMs are therefore called MONOPROCESS since only one process may be active atany given moment.

Figure 153 : Monoprocess FMM

PROCESS DEFINITION

PROCESS DATA

– Multiprocess FMM

For the second example, let’s take the FMM that handles the call setup. When a call isset up, a process is created which uses a data area to store all the information requiredfor this call. This FMM will be handling one subscriber for a more or less prolongedtime; if during this time, another subscriber starts a call, the FMM will have to store datafor this second call. The FMM will then not be able to use the same data area, since ithas already been taken by the first call. If the FMM must handle multiple callssimultaneously, independent data areas (one for each call) have to be created.

The FMMs that are implemented in this way are called MULTIPROCESS FMMs. In thiscase, an independent data area is created for each new request. When the executionof a request is completed, the data area used for it is released. The FMM part that is incharge of creating and releasing the data area is called SUPERVISORY PART and hasits own data area. The FMM part responsible for carrying out the actual FMM function,is called APPLICATION PART.

The execution of the supervisory part is known as a supervisory process , and theexecution of the application part on one data area is called an application process .This means that multiprocess FMMs always have one supervisory process and avariable number of application processes.

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Figure 154 : Multiprocess FMM

SUPERVISORY PART

PROCESS DATA

APPLICATION PART

PROCESS DEFINITION

PROCESS DATA

PROCESS DEFINITION

– Monoprocess multidevice FMM

Up to now, we have seen two different types of FMM – monoprocess and multiprocess– each having its own specific structure and operating mode. As seen before, amonoprocess FMM can only handle one execution request at a time. There is,however, a special type of FMMs which has a single process but can handle more thanone request simultaneously.

Let us consider an FMM that scans the line circuits. The number of these circuits isfixed and known beforehand; furthermore, the scan must be executed continuously.Under these conditions, one data area per circuit will be required but the number ofthese areas is also fixed.

We could implement this FMM as a multiprocess one. In this case, the FMMsupervisory part would have to create an application process per circuit only once, atthe initialization time. All these processes, however, would have to exist forever sincethe scan must be performed continuously.

This solution does not seem to be the smartest, nor the most adequate. The alternativeis a monoprocess FMM that uses one data area per device. The result is then a singleprocess that controls a fixed number of circuits. This type of FMM, i.e. implemented inthis way, is known as a MONOPROCESS MULTIDEVICE.

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Figure 155 : Monoprocess Multidevice FMM

DEVICE 1

DEVICE 2

DEVICE N

PROCESS DEFINITION

d. Overlay FMMs

There are kinds of FMM which do not require a periodic performance or/and whichoccupy too much memory. FMMs with these properties are not resident (permanently)in the CE memory, and are therefore called OVERLAY FMM –OFMM–. They are storedon the system disk and will only be loaded into CE memory when their performance isneeded. At this moment the FMM program code and data will be set up in a particularzone of the CE, called ’Overlay Zone’.

e. Shell based systems

The FMMs that we saw so far are implemented as one software unit. There are anumber of drawbacks though with this implementation:

– the maximum size of a software unit is 64 kB;

– if the software is CDE dependent a lot of variants have to be written and maintained;

– if the software handles signalling, possibly different versions of signalling have to behandled, so again a lot of variants have to be written and maintained.

To solve all of these problems, an FMM can be implemented as a so–called ShellBased System (SBS) . The FMM contains a shell and a number of entities. Each entityperforms a specific task. Figure 156 gives an example.

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Figure 156 : Shell based system

��

��

��

��

��

��

S12 m

essages

internal messages

S12 m

essages

Usually the shell is implemented as an FMM. The entities can be:

– a part of the FMM;

– an SSM (with interface procedures);

– a procedure that is linked with the FMM to form one software unit.

There are a number of rules in an SBS. Here are a few:

– only the shell can receive S12 messages from other software units;

– both the shell and the entities can send messages to other FMMs;

– the entities communicate indirectly with each other, via the shell;

– internal messages are used:

– for the communication between the entities;

– for the communication between the shell and the entities.

– the shell and the entities use shared data.

3.2.2 Messages

a. Standard messages

In the previous section, we have seen how the communication between FMMs isperformed through normalized information structures, called MESSAGES. Thesemessages have the following properties:

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– When a message is sent, the information will be placed into a 64–byte datastructure, called MESSAGE BUFFER. Each Control Element (CE) will have a certainstock (pool) of message buffers.

– The message buffer structure consists of two parts: header and body . The headeris used to route the message towards the destination FMM and occupies 16 bytes. Itincludes among others, the following information fields: a number (msg_identity),which uniquely defines the message; a priority; message type; etc, as shown in thenext figure. The body, in turn, is divided into two parts. The first part is the text, orthe actual information, which occupies 40 bytes. The second part is reserved for useby the Operating System and occupies 8 bytes.

– Each message structure is defined “off_line” and is known by different FMMs whichmust use them. When an FMM has to send a message, it must first request one ofthe free message buffers. The Operating System will search for a free buffer andreturn a pointer with the message buffer starting address to the requesting FMM.This pointer will be used to copy the message to the message buffer. In the sameway, a pointer will be passed to the destination FMM, where it will be used to readthe message information.

Figure 157 : Message structure

INFORMATION LENGTH

TYPE

MSG–IDENTITYPRIORITY

DESTINATIONSOURCE

BODY

TEXT (40 BYTES MAXIMUM)

RESERVED WORDS

HEADER

b. Types of standard messages

Although up to now, we have basically referred to the messages as the communicationmeans between FMMs, they are actually used for the intercommunication of FMMprocesses. The messages will always be sent/received through the “message buffer”mechanism. There are two main types of messages depending on whether thedestination process is known by the originating process or not. These two types are:

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– BASIC MESSAGE:

This type of message is sent from an FMM (process) to another FMM (process). Theactual destination process is not specified when the message is sent. Determination ofthe destination process will be a function of the Operating System.

As an example of this type of messages, let us take the FMM which handles the call setup. When a new call is set up, there is no active process for its handling; thus, the firstmessage that the FMM (which detected the call set up), sends to the former FMM, isthe one without a specific destination, a basic message.

– DIRECTED MESSAGE:

This type of message is sent by a process to a known destination process.

In the above example, when the call set up continues, the originating process alreadyknows which process is attending to it. Therefore, in this case, the originating processwill send the events to the destination process in the form of directed messages.

There are two rules to be taken into account when sending and receiving messages.These rules, graphically represented in the next figure, are:

– A supervisory process may send and receive basic as well as directed messages.

– An application process may only receive directed messages; however, it may sendeither basic or directed ones.

The same rules that apply to the supervisory part of a multiprocess FMM also apply tothe monoprocess FMMs. Therefore, the only process of a monoprocess FMM, will becalled supervisory process.

Figure 158 : Rules for sending & receiving messages

SUPERVISORY PROCESS

APPLICATION PROCESS

BASIC

DIRECTED

DIRECTED

BASIC

DIRECTED

BASIC

DIRECTED

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c. Creation of application processes

Now that we have studied the different types of FMMs and messages that are generallyfound in the system, we can describe the mechanism used to create an applicationprocess for a multiprocess FMM. The steps followed to achieve this creation are shownin the next figure.

[ 1 ]A basic message is sent from a process to the supervisory process of an FMM.As a result, this supervisory process decides to create an application process thatwill handle the request received in the message.

[ 2 ]The supervisory process will use the O.S. services to create the applicationprocess. The new process will have an identity that is known, from the time of itscreation, by the supervisory process.

[ 3 ]At this point, the supervisory process can send a DIRECTED message to thecreated application process since it knows its identity. This message will containall the information that the supervisory process received in the basic message.

[ 4 ]The application process reads the information received in the directed messageand starts its execution. The result of this execution may be either a basicmessage to another process or a directed message to the process that sent thefirst basic message. From now on, the originating process will communicate withthis application process through DIRECTED messages (remember that theapplication processes can only receive directed messages).

[ 5 ]When the application process has completed its task, it will notify this and theresources assigned to it will be released (process data).

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Figure 159 : Application process. Creation

ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ

PROCESS SUPERVISORY PROCESS

APPLICATION PROCESS

1

4

3

2

5

4

BASIC

DIRECTED

DIRECTED

BASIC

OTHER FMM

ANY

(PROCESS)

OPERATING

SYSTEM

d. User buffer

When a process has to send more than fourty bytes, it uses two buffers: a messagebuffer and a user buffer. The user buffer is a memory area that can have any size up to64 kB. The user buffers are organised in memory pools. Each memory pool contains anumber of buffers of a particular size. Within a control element you can have up to 10different memory pools. A control element can therefore have user buffers of 10different sizes.

The message buffer is organized exactly as seen before; however, the header containsan indicator notifying that it has a user buffer associated with it, while the text includesa field indicating the length and the address of the user buffer.

When a process wants to send a message with a user buffer, it delivers them to OS.OS then puts the message in a delivery queue and presents it when appropriate. Theprocess that receives the message obtains the length and address of the user buffer toread the information contained therein.

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Figure 160 : Message buffer with associated user buffer

HEADER

MESSSAGEBUFFER

USERBUFFER

POINTER

LENGHT

1

DATA

DATA

TEXT

e. Compound messages

The messages discussed so far have a fixed structure: both the length of thesemessages and the layout of the messages is fixed. When the higher level FMMscommunicate, the same message has to be sent a number of times during a call, butthe layout may differ depending on circumstances, such as when the message is sentand what kind of facilities the subscribers have.

For ISDN subscribers there is an extra difficulty: they communicate with the exchangewith ISDN signalling, that uses optional components. These messages have to be sentfrom one FMM to an other in the form of a S12 message. The standard S12 messagesdo not support optional components.

To cope with these restrictions of the standard S12 messages, a different type of S12message can be used: the compound message. A compound message contains anumber of message blocks. Each message block has a message block identifier(MBID), a length indication and the contents part.

3.2.3 System Support Machine (SSM)

a. Definition and characteristics

Generally, the software modules are implemented as FMMs and written in the highlevel language CHILL. The FMM not only offers specific advantages (modularity andflexibility), it also has some drawbacks:

– Many times, the software must be available and ready to attend to certain events,e.g. a hardware interrupt. This readiness is not furnished by the FMM model since,as mentioned earlier, the FMMs are only started through the reception of messages.

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– In the case of common support routines which we want to group into independentSW modules, we could actually use FMMs. However, every time one of thoseroutines were to be used, a message would then have to be sent to the FMMcontaining them. This would involve a great shuffle of messages and overload, withthe subsequent loss of time for their reception and transmission.

The reasons exposed here are more than enough to think out a different module, onemodule to complement the FMMs and solve the above problems. This software moduleis known as SYSTEM SUPPORT MACHINE (SSM).

An SSM is designed as a set of routines, all within the same module, that carry outsome support function for one or more FMMs. These routines are not started throughmessages, but through procedure calls; although they can actually send messages tothe FMMs.

b. Types of routines in a SSM

– Interface routines

These routines are started by FMM processes through procedure calls. In this case, theroutines are executed as if they were part of the calling program. The interface routinesmay send and receive directed messages, such as the answer–back message from theFMM to which a message was previously sent. The routines of this type are the onlyones that may be called by an FMM process. Furthermore, for a process to be able tomake use of these routines, the process and the SSM interface routine must be in thesame CE.

– Clocked procedures

These routines are run periodically. They are mainly used for scanning telephonicdevices. The interrupts are masked out during the execution of these routines, so theywill not be interrupted by a timer or any hardware event.

– Interrupt procedures

These routines are executed whenever a hardware interrupt takes place. Just as theclocked procedures, they also run with the interrupts masked out.

For this reason, both the periodic and the interrupt procedures must have a shortexecution time so that no hardware interrupts are missed. Consequently, these routineswill not be able to send or receive messages as this would take too long. Thus,functions that require a longer execution time, or the sending of messages, will not bedesigned with these type of routines; instead, they will be designed as Event Handlers.

– Event Handlers

These routines run with the interrupts allowed and, therefore, will be able to sendmessages.Their main function is to prepare and send messages based on the data

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provided to them by the periodic and/or interrupt procedures. These routines have anassociated flag (event flag) that, when set by the periodic and/or interrupt procedures,or even FMMs processes, indicates to the Operating System that the Event Handlermust be started. Once the execution of the Event Handler has ended, control is givenback to the Operating System.

Figure 161 : Interconnection of an SSM and other modules

MESSAGEO. S.

MESSAGES

FMM

INTERFACE INTERRUPT EVENT

HANDLER

SSM

SSM ROUTINES

MESSAGES

MESSAGES

DIRECTED

PROCEDURE

CLOCKED

PROCEDURE PROCEDURE

3.3 Communication between processes

As we already know, the software stored in the different control elements is organized in theform of FMMs, SSMs, and OS modules. Of all these software tools, the FMMs are thoseused to create processes that perform the application functions. These processes exchangeinformation with each other by means of standardized messages.

The transfer of these messages, from the originating to the destination process, is carriedout via the OS, and may be established within a single microprocessor or, between differentCEs through the internal switching network. The following figure shows an example of thetransmission of messages between the A, B and Y FMMs resident in the CE1 and CE2control elements.

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Figure 162 : Communication between processes

FMM

A

OPERATING SYSTEM

FMM

B

OPERATING SYSTEM

FMM

Y

DSN

CE 1

CE 2

This transfer works as follows: the originating process must first obtain a message bufferand fill it in correctly and then it must ask the OS for its transmission. Thanks to theOperating System, the transmission of these messages is completely transparent to theprocesses involved. The destination process is known from the type of message and theinformation contained in the message header, and the path to follow is established by analgorithm called routing. The routing result may be ’internal’ (communication within theactual CE) or ’external’ (communication between different CEs).

There are two different ways to start the routing procedure, depending on whether themessage is a directed or a basic one. If it is a directed message, the originating processknows the identity of the destination process, and writes it into the message header. Thisdestination process identity contains the identity of the CE where the process is executed.Therefore, the routing will consist of comparing the two CE identities (origin and destination)and deciding whether the message is internal or external.

In the case of a basic message, the originating process does not know the identity of thedestination process. In this case, routing is essentially based on the message number. Forthis situation, the OS data provides a set of tables called MRT ’Message Routing Tables’ ineach system control element. These tables contain for every message the informationnecessary to find out the destination process identity or the CE where the destination FMMresides.

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Figure 163 : Routing of ’Basic’ and ’Directed’ messages

Ps–1

Pa–1

FMMA

OPERATING SYSTEM

MRT

INFO

ExternalInternal

BASIC

MESSAGE

HEADER

Ps–1

Pa–1

FMMB

OPERATING SYSTEMHEADER

INFO

ExternalInternal

DIRECTED

MESSAGE

As we already know, the basic difference between the two types of messages is that,directed messages may be sent to any type of process (supervisory or application), whereasbasic messages may be sent only to supervisory processes. The reason for this is that therouting result is the identity of the destination FMM and this identity only provides a link tothe supervisory process in an unambiguous manner.

3.3.1 Communication within the same CE

If the routing result indicates that the message is internal, the Operating System mustcomplete the transmission by presenting the message to the destination process. Thispresentation is not carried out immediately, instead the message is inserted in the deliveringqueues with its corresponding priority. The message stays in this queue until the momentwhen it is presented to the destination process.

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Figure 164 : Internal communication

P1

P2FMM

A

OPERATING SYSTEM

FMM

B

MRT

INTERNAL

DELIVERING QUEUES

HEADER

INFO

MESSAGE

3.3.2 Communication over a virtual path (VP)

Virtual Paths (VP) are temporary paths that are used exclusively for the transmission of amessage and are released after the message is completely received. This is the mostcommonly used type of path and it is dedicated to the support of individual exchanges ofinformation.

As we already know, a path can be released by sending two or more ’Idle’ or ’Clear’commands through the actual path. The message arrival acknowledgements are also sentthrough virtual paths.

a. Communication with messages

On the other hand, if the Operating System decides, based on the routing result, thatthe message is external, it will be necessary to establish a communication path throughthe network with the remote control element that contains the destination process.Once the identity of the destination CE is known, the Operating System must see to thetransmission of the message. This transmission is carried out in accordance with thesteps.

[ 1 ]Copy the message buffer to the TI memory.First a launching buffer is reserved in the TI Packet RAM. The message is copiedfrom the Main Memory into this buffer. Of course, the message will be precededby the SELECT commands required to establish the path towards the destination

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CE, and the SOP or Start Of Packet indicator. Furthermore, a CRC and the EOPor End Of Packet command are appended to it.

[ 2 ]Order to launch the buffer:Once the buffer is copied, the OS orders its launching using of the TI controlregisters, where a command is given to launch the packet in any free channel. Inthe response command the TI indicates the chosen channel identity. The TIhardware sends the message–words from the buffer to the chosen channel, in anautonomous way. Once the launch is completed, the TI notifies the OS whichreleases the associated buffer of the actual TI packet RAM.

Figure 165 : Transmission of an external message

TI

MICRO

P–RAM

TI

P–RAM

MICRO

DSN

1

2

34

5

Main

Memory

Main

Memory

[ 3 ]Progress through the network:The SELECT commands, written at the beginning of the packet, establish anetwork path that terminates at the TI of the required control element.

[ 4 ]Collection and storage in the destination TI:The SELECT commands of the packet sent stay in the different networkmultiports, so that the first word arriving at the TI is the Start Of Packet, SOP. Thisindicator causes the TI hardware to collect all the incoming information until thearrival of the EOP and store it in its internal memory.

[ 5 ]Copy the buffer to the main memory of the destination CE:

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Once the EOP is detected, the TI notifies the microprocessor through theappropriate registers. This provokes the entry of the OS which transfers themessage to the main memory, checks the CRC, and releases the buffer used.After the message is copied to the destination, the Operating System againanalyzes the message in order to obtain the identity of the destination processand stores it in a presentation queue.

Besides the well–known NACK mechanism (backward information), provided by thenetwork when the continuation of the path establishment proves impossible, theOperating System uses an error protection protocol. This protocol consists of thetransmission of an acknowledgement with CRC. This acknowledgement is materializedin the transmission of an acknowledgement message (ACK).

If the message does not arrive within a specified period of time (’To’ in the figure), theoriginating Operating System retries the message launch a certain number ofconsecutive times (usually three). If the acknowledgement is still not received, apartfrom other actions to be taken, the appropriate error reports are generated and senttowards the defence CE responsible for error handling.

Figure 166 : Error protection

CE1 CE2 DEF

Message 1 (1)

Ack

Message 2 (N)

Error Report

To

To

Message 2 (1)

Message 2 (2)

However, this whole operation is transparent to the processes involved and they are notnotified of the correct or incorrect message arrival. Therefore, the actual processes mustsupport, if required, their own acknowledgement protocol.

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To continue with these ideas, there are basically two strategies to establish a paththrough the switching network: the virtual paths and the user paths.

b. Communication with user buffers

The user buffer transmission is carried out by splitting it up into 64–byte portions (dueto the mapping of the Terminal Interface P–RAM). These portions are sent through thenetwork using a held–up path towards the destination CE. This path is established bythe first packet sent and is held by ’SPATA’ words until the transmission of the lastpacket. The destination OS assembles the incoming portions using the previouslyreserved area.

Difference must be made between ”small user buffers” (up to 128 bytes) and ”largeuser buffers”.

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Figure 167 : UB transfer indication

USER OS OS USERMSG_UB

MSG (keep conn.) Get UB

UB[1]

(UB[2]) (clr conn.)

ACKMSG_UB

ÉÉÉÉÁÁÁÁÁÁ

MSG

UB

ÉÉÉÉÁÁÁÁÁÁÁÁ É

É

ÁÁÁ

MSG

UB

Held

Path

U.B. up to 128 bytes

U.B. 256 bytes or more

ÉÉÉÉÁÁÁÁÁÁÁÁ

ÉÉÉÉ

ÁÁÁÁ

ÁÁÁÁ

É

ÁÁÁ

USER OS OS USERMSG_UB

MSG (VP)

UB[1](keep conn.)

(UB[n]) (clr conn.)

MSG_UB

MSG

UB

MSG

UB

Via2Held

Paths

Get U.B. (VP) Get UB

ACK_UB (VP)

...

ACK

ACK

ACK

– User Buffers up to 128 bytes

In this case the user sends the ”message with user buffer” to OS (see figure 167). OStransmits this message and the user buffer to the remote side via the DSN. The firstpacket sets up the connection and the last packet clears the connection. At the end anacknowledgement is sent back to the originating OS. The first packet contains themessage itself (standard S12 message). The header information indicates the

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presence of a user buffer, so that the destination OS can allocate a user buffer. At theend of the scenario the ”message with user buffer” is sent towards the user.

– User Buffers of 256 bytes or more

This scenario also starts with the transmission of the ”message with user buffer”towards the OS. In this case the originating side sends a request (message via virtualpath) to the destination side for a user buffer. The destination OS allocates a buffer andsends an acknowledge back (also message via a virtual path). This ACK_UB messagecontains the pointer to the user buffer (in the destination CE). Then the user buffer istransmitted via two held paths (see figure 168, the first packet makes the connectionand the last packet clears the connection for each held path). Finally the A1000 S12MSG is sent via a virtual path. This message already contains the new pointer (pointsto the user buffer in the destination CE). The complete ”message with user buffer” isdelivered to the user.

Figure 168 : Transmission of a user buffer via two held paths

TI

P–RAM

TI

P–RAMDSN

1

2

3

N

1

2

3

N

1

3

2

N

1

3

1

3

2

N

1

3

1

2

3

N

1

2

3

N

SPLIT 1

SPLIT 2

SPLIT 1

SPLIT 2

VP 1

VP 2

Another strategy used to save transfer time is to pack the data in the outgoing channel.Up to now, we have seen that eight of the sixteen bits of an A1000 S12 PCM channelare used to carry data through the network. For user buffer transfers the ’bitpacking’ method is used. This new method consists on carrying 12 bits instead of 8on each PCM channel thus achieving a better transfer time.

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Figure 169 : Packing strategy

Protocol Bits BYTE 1Protocol Bits BYTE 2

Protocol Bits BYTE 3

Protocol Bits B2–L BYTE 1Protocol Bits B2–H BYTE 3

Protocol Bits B5–L BYTE 4

8

4 8

1

2

3

1

2

3

UNPACKED

PACKED

Note: Another way to send information greater than fourty bytes is to organize it in successivemessage buffers. This strategy saves the time spent in the search for the user buffers and in thesplitting up of the buffer, but increases the transmission time as it involves the routing of each andevery one of the messages making up the series to be sent.

3.3.3 Communication over a user controlled path (UCP)

There are also User Controlled Paths (UCP). The main feature of these user paths istheir two–way and lasting nature. The paths are assigned to two processes, one at eachpath end. These two processes are considered the path users. This type of path is primarilyused to create a conversation path between two subscribers or two trunks located indifferent control elements, but also for the massive exchange of control data between CEs.Therefore, unlike the virtual paths, the UCPs are established and released under direct usercontrol. These two functions, path establishment and release, are performed using theservices offered by the operating system.

When a user, for instance the process PA, seeks to establish a UCP towards the remoteprocess, PB; it asks the OS for a user path.(step 1). This request assigns, from this momenton and in a bi–univocal manner, the process PA to the identity of the path that will becreated. This means that all the messages that arrive through the created UCP willautomatically be sent to process PA.

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Figure 170 : Request of an UCP

O.S. O.S.

PA BP

1

CE 1 CE 2

DSN

Now the originating process PA has to associate the UCP to the destination process, PB. Inorder to achieve this, PA requests the transmission of a basic message via the UCP (step 2).

As a consequence of the request, the Operating System sends a message notifying thecreation of the UCP to the destination side OS (step 3). The latter, defines a new UCPidentity that will be significant within that CE (CE 2), and responds with the creation of thereturn path (step 4). At this moment, the two–way path is established in the network,although it has not yet been assigned to any process on the destination side.

All messages transmitted through a UCP carry a UCP identifier which is relevant on theoriginating side within the message body; therefore, once the message has reached thedestination CE (step 5), the OS there must change that identity into one that is locallysignificant. This is done in a similar way for each message arriving through a UCP. However,the first message must be sent by use of the routing algorithm (basic message), for noprocess has yet been assigned to the UCP. Once the OS finds out the destination process, itplaces the message in a queue and hands it over to process PB when required (step 6).

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Figure 171 : Notification to the destination process

DSNO.S.

PA BP

CE 1 CE 2

4

5 62

3O.S.

The receiving process must now ask the OS for its association to the created UCP (step 7).

Figure 172 : Answer from the destination process

DSNO.S. O.S.

PA BP

CE 1 CE 2

7

Once the path is established, and the processes involved are identified, the path can beused for the fast exchange of messages. However, these user paths are used above all forthe connection of telephonic devices; that is, subscriber to subscriber, subscriber to trunk,subscriber to service circuit, trunk to service circuit, etc. In order to carry out theseconnections, it is necessary to link the established user path with the port and channelcorresponding to the external telephonic device. This link is performed through a request tothe operating system. The OS orders the Terminal Interface internal switching to establishthe duplex connection by a ’Cut through’ operation. This task is performed in the two CEsinvolved.

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Figure 173 : Switching in the Terminal Interface

Tx

Rx

Tx

Rx

TERMINAL INTERFACE

CH A

CH B

CH N

CH M

CLUSTER UCP

P–RAM

Figure 174 : Connection of a subscriber to a UCP

TERMINAL INTERFACE

CH O

CH P

CH C

CH D

TERMINAL INTERFACE

CH A

CH B

CH N

CH M

ASMHARDWARE

DSN

ASMHARDWARE

Either process (origin or destination) may ask the Operating System for the release of theuser path while it is being used. As a consequence of this release request, the respectiveOSs release the established communication and notify the associated processes.

3.3.4 Communication with the internal packet protocol (IPP)

The communication mechanisms discussed so far provide services that are sufficientlygeneric for the transmission of messages. Yet there still are some limitations:

� the time that a message must wait in the delivery queues

� none of the previous procedures allows for the transmission of messages to remoteOBCs

� the routing algorithm can provoke a work overload in some control elements, especiallythose associated with packet handling (N7, X.25, ISDN,...).

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These problems are solved by the use of a new internal communication protocol called IPP(’Internal Packet Protocol’). This protocol was introduced to support the transfer ofmessages between an N7 user, resident in the module that provides access to the speechchannel, and the module that provides access to the associate signalling trunk. Thisintroduction considerably increased the performance of the message transfer between them,and its use was subsequently extended to include the data and packet communicationareas.

Figure 175 : IPP protocol in N7

INCOMINGDTM

OUTGOINGDTM

ACE

P&L C&T

ch x

ch 16

ch y

ch 16

IPP

IPP

IPP

UCPUCP

N.7 DTM N.7 DTM

Due to design reasons, there are different types of IPP users: for N7 application, for X.25,OSI stack, etc. These software modules are called interworkings (IWs), and, as we will seelater, in order to take full advantage of the IPP protocol, it is suggested to code them under aparticular structure so that they can be activated from any other software module byprocedure calls.

The part of the Operating System responsible for managing this protocol can support onlyone kind of user, a module called Common IPP (CIPP) or IPP Handler is added between theinterworkings and the actual OS.

The functions of this new module are to provide multiple users with access to the IPPs, toreceive and route the messages towards their corresponding points, to reserve the requiredchannels in the network as well as in the cluster PCM links for the transparent transfer ofIPP packets to the OBC/s through the Terminal Interface, etc.

When a process needs to transmit data using the IPPs, it stores the information into amemory buffer and through the corresponding IW, passes the buffer to the Common IPPwith the identity of the destination CE or OBC and the destination IPP user identification inthat CE.

The Common IPP adds an IPP header –with the identities related to the transfer over IPPs–to the packet and transmits it to the destination CE.

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An important factor to be taken into account is the size of the information to be sent. If theinformation is too long to be sent in a single message, the Common IPP must find analternative way for its transmission. The most commonly used procedure is to place theinformation in a message buffer and a user buffer – ’Segmenting’ –. If the information totransfer is excessively long, the previous procedure becomes too slow. Therefore, thetransfer time can be reduced by using of a transmission mechanism similar to the userbuffer, that is, splitting up the information into two halves, and sending them through twopaths – ’Splitting’ –. Both procedures are invalid for communication with OBCs, given theneed to use held–up paths (not supported by the OBC Operating System).

Figure 176 : Transference of an IPP packet

HEADER

TEXT

IPP HEADER

DATA

MESSSAGE

BUFFER

IPP PACKET

DATA

CE or OBC Identity

IW Identity

The transmission of medium length messages (similar to the N7 packet size) or to/fromOBCs, is carried out by a strategy called ’Chopping’ . This mechanism consists of dividingup the information into multiple portions that form a set of separated but related messages.For very small messages the data from several users are grouped – ’Grouping’ – and sentas a whole in a single message buffer, thereby significantly improving the traffic flowbetween micros.

At the destination the message is passed to the Common IPP of that side, which stores it ina new buffer and hands it over to the destination IW through the ’procedure call’.

As we have seen, one reason that supports the advance in performance is the fact that theIPP implementation offers a dedicated message transfer. By dedicated, we mean that themessages are directly handed over to the corresponding user module, without having topass through the routing or message presentation queue steps. However, one first drawbackis that the destination user (IW) must be designed as an SSM routine. Furthermore, theusers must have knowledge of the different identities of the CEs, OBCs and IWs involved inthe communication.

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Figure 177 : IPP levels

NH BYPASS

FMMs SSMs

INTERWORKING

Common IPP

OPERATING SYSTEM

DIGITAL SWITCHING NETWORK

S–12MESSAGES

IPPPACKET

IPPPACKET

InternalInterface

The Common IPP or IPP Handler supports the two protocol types: connection oriented andconnection–less. The connection oriented protocol is mainly designed for the communicationwith OBCs. In this case, the CIPP manages a table to link the connection identities with theassociated OBC identities. The second case (connection–less) allows the transmission ofdata units to CEs or OBCs without any sequence number.

3.4 Software modules

3.4.1 Logical grouping of the Call Handling software into call control planes

In every access module (ASM, ISM, IPTM, ...) there is software to handle a call. Figure 178shows the building blocks in the call origination and in the call termination modules. Thebuilding blocks are always present, independent of the type of access: BA, PRA, analogueline or trunk.

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Figure 178 : Call Handling building blocks

SIGNALLING HANDLING

DEVICE HANDLING

TRUNK SEARCH

SUBSCRIBER IDENTIFICATION

DSN

BA

PRA

Analogue Line

Trunk (CAS or Nr7)

CALL AND FACILITYCONTROL SYSTEM

SIGNALLING HANDLING

DEVICE HANDLING

BA

PRA

Analogue Line

Trunk (CAS or Nr7)

CALL ORIGINATION CALL TERMINATION

AUXILIARY CONTROL ELEMENTS

PARM

SIGNALLING HANDLING

PREFIXANALYSIS

These different blocks can be placed in 3 planes:

� Call Control Plane;

� Protocol Plane;

� Connection Plane.

Each of these planes performs tasks within their own area.

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Figure 179 : Call Handling Planes

TrunkSearch

Subscriber

Identification

Prefix

Analysis

DeviceHandling

Signalling

Handling

Call and FacilityControl System

DeviceHandling

Signalling

Handling


CONNECTION PLANE

PROTOCOL PLANE

CALL CONTROLPLANE

DEFINE CALLED DEVICE

PARM

a. Connection Plane (Device Handling)

The main tasks are:

– cluster handling (seizure and release);

– speech path control (join, release, ...);

– Allocation of devices to various requesters.

In general it consists of an FMM and SSM. It also keeps the busy/free status of thedevices (therefore the FMM part is a monoprocess multidevice). The type of device isalso dependent upon the module, e.g: trunks for a DTM, subscriber lines for an ASM,B–channels for a PRA, ...Not only access modules contain a device handler. The Service Circuit Module forexample, also contains a device handler where the devices are the senders/receivers.

b. Protocol Plane (Signalling Handling)

One of the major tasks of the exchange during the setup of a call is signalling.

– Line signalling:

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Hardware events coming from the Device Handler (changes in the state of thesubscriber line) are sent towards the signalling software. These events must betranslated into telephonic events which can be passed to a higher software level.Conversely, logical telephonic signals coming from the higher level software mustbe translated into commands for the operation of the subscriber’s line equipment.Examples: off–hook of a subscriber, trunk seizure, clear forward/backward, ...

The line signalling function is performed by the signalling handling software.

– Register signalling:

Register signalling deals with the supervision of transmitting and receivingidentities. These identities can be sent by the subscriber via his push button set ordial set, or via MF/R2 or No7 for incoming/outgoing calls.

For a push button set the DTMF code is detected in the hardware of the SCM.The device handler collects the result from the hardware and delivers it towardsthe signalling handling software. The same principle is used for trunks with MFsignalling.

For a dial set the digits enter the ASM by means of line events, and are thereforedetected in the device handler of this module. The device handler delivers thedigits (after counting the pulses) to the signalling handling software.

For incoming trunks with No7 , the messages enter the signalling handlingsoftware and contain the digits.

– Combining line and register signalling:

When using more sophisticated signalling systems, it becomes possible tocombine some events in one message. E.g: if a Q931_SETUP (ISDN) messageenters the exchange, it combines the seizure (line signalling) and the digits(register signalling) in one message. The same applies for the Nr7 messagesused on trunks.

Conclusion:

Whatever type of signalling is used, the result is always the same. The signallinghandling software will collect the digits so they can be transmitted towards the highersoftware level, the Call Control.

Summary of the main functions:

– Protocol interpretation and translation into Call Control plane terminology and viceversa.

– Protocol interpretation and translation into Connection plane terminology and viceversa.

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– Establishing a datalink.

– Communication within the protocol plane (=inter–signalling communication)

– Administration of timers and call references used in call control procedures.

– Administration of access resources.

– Handling of auxiliary devices such as senders and receivers.

c. Call Control Plane

This is the highest software level within the module. It controls the setup and therelease (during unstable phase) of the call. When events enter the signalling handlingsoftware, it can check in the data if call control should be informed or if the event istreated locally.

The main tasks are:

– Number Analysis

– Routing

– Call configuration management (complex facilities)

– Registration / erasure / activation / deactivation of features ordered by thesubscriber

The call control plane is signalling independent

The call control plane is steered by data coming from the building blocks within thegroup: ”DEFINE CALLED DEVICE”. These building blocks are discussed in the nextchapters.

Figure 180 gives a more detailed view of the call handling planes. The software blocksare described in the following chapters.

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Figure 180 : Call handling planes

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

CFCS

TRA TRC PATED LSIF

ASM HARDWARE DTM HARDWARE

SIG

DH

SCM HARDWARE

DEVICE HANDLER

SIGNALLING

ARTA

DHDEVICE HANDLER

DHDEVICE HANDLER

CONNECTION PLANE

PROTOCOL PLANE

SIGSIGNALLING

OPERATING SYSTEM and DATABASE

CALL SERVICES

CALL AND FACILITY CONTROL SYSTEM

CALL CONTROL PLANE

SIGSIGNALLING

SIGSIGNALLING

3.4.2 Operating System

The A1000 S12 software is divided into nine subsystems. Each subsystem has its specificfunction.

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Figure 181 : Software Subsystems

ADMINISTRATION

MAINTENANCE DATABASE OPERATINGSYSTEM

CALLCONTROL

CALLSERVICES

CHARGING RESOURCEMANAGER

DEVICEHANDLER

CALLHANDLING TELEPHONIC FUNCTIONS

The Operating System is the subsystem that provides support to the rest of the system, bymanaging the own resources of each processor. These resources are, as in any otherprocessor system, the time and the memory of each one of them.

Regarding the time, the Operating System is in charge of its management, since it is theOperating System which determines the task to be performed at any given moment.

The memory, having a limited capacity, will also be controlled by the Operating System,which is in charge of its distribution among the programs that require it.

For these reasons, the Operating System will be stored in all the CEs of the differentmodules.

Given its control over time and memory, the Operating System will be essential for theexistence of the FMMs and the SSMs since it will allow the communication throughmessages and will take part in the activation process of the different SSM routines.

This subsystem will also handle the clock and peripheral interrupts, thereby allowing theexecution of the appropriate SSM routine. Another function of the Operating System will beto control the switching network and the Terminal Interface, since it will establish the physicalcommunication paths between the different system modules.

Finally, it will be in charge of the reloading and recovery of the different control elements forwhich purpose it is equipped with error handling elements. Once an error is detected, theOperating System will interact with the Maintenance modules for subsequent recovery.

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The main functions of the Operating System can thus be summarized as follows:

� Manage processor time: For the OS to be able to perform this function, there is a seriesof different tasks to be carried out by the processor. The operating system indicates at alltimes which of these tasks is executed according to the previously assigned priority. TheOS will have FIFO queues for managing each of these priorities.

� Manage main and mass memory: When creating a process, the Operating Systemprovides it with a data area, and when it terminates the Operating System releases thisarea so that it may be allocated to a new process. The OS provides the message buffersallowing these processes to intercommunicate. It also controls the memory areasreserved for the overlay programs, indicating the relevant areas and their respectivecontents.

� Timing: The OS will start the clocked procedures (inside SSMs) at a fixed time intervalper routine.Other processes (FMMs) can start relative and absolute timers (periodic or not) and theOS will inform the process upon expiration of the timer(s).

� Message Handling: OS will deliver the messages to the appropriate processes accordingto their priority.

� Control the switching network and the Terminal Interface: The OS allows for thetransmission and reception of messages by controlling the Terminal Interface memory,ports and channels. It also controls the switching network since it will be in charge ofwriting the network control commands for the establishment and release of paths.

� CE load and initialization: A set of OS modules are responsible for requesting the load,when necessary, of the different programs loaded in the processor memory. They arealso responsible for managing the initialization process of the different programs.

� Control the man–machine communication peripherals: The whole input/output system ispart of the Operating System; the OS will therefore contain the controllers for thedifferent peripherals.

� Control the loading and execution of overlay programs: The OS will control the loadingand execution of these programs when required.

Functionally, the Operating System can be broken down into several functions, all of themindependent of each other. This basic breakdown is as follows:

� Programs support: Creates the conditions necessary for the execution of the differentFMMs and SSMs. It supports the sequential execution of the processes, for whichpurpose it “handles the processes” (creates, activates and terminates them) and performsthe process time planning. It provides time services for the implementation of time–outs.It collects, controls and initiates local actions for all errors detected. It allows for theexecution of Overlay programs.

� CEs communication interface: carrying out allows the rest of the Operating System, tosend/receive messages to/from the Operating System of other modules.

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� Network Handler: Directly controls the TI and the switching network.

� Loaders and Initializers: They obtain the load packet, load it into memory and initialize thedifferent programs.

� Input/Output System (IOS): In charge of the peripherals, the man–machinecommunication and direct memory access.

Figure 182 : Operating System functional breakdown

ALLCEs

P & L

NETWORK &CIRCUITRYHANDLER

PROGRAMSSUPPORT

CEsINTERFACE

LOADERS&INITIALISERS

INPUT /OUTPUTSYSTEM

All the kernel OS functions are loaded in all the CEs, but specific functions are loaded only inthe corresponding CEs. In the above example, the Operating System controls the cross–over in the line TCEs, the input/output system in the P&L TCE, etc.

3.4.3 Database

So far we have seen that all software functions are implemented as FMMs, SSMs or specificOS modules which will have to handle subscriber and exchange data. In previous systems,each program had its own data file. This method has two drawbacks: REDUNDANCY, whichmeans that a piece of data can be stored in more than one place and be used by more thanone program, and INCONSISTENCY, which occurs when a program updates a piece of data

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in its own data file, without changing it in the data files of the other programs in which thesame piece of data is stored.

a. Objectives and use

Given modular structure of the software , a piece of data can be used by differentFMMs (data users) not necessarily belonging to the same subsystem and, due to theA1000 S12 distributed control , these users will probably be executed in differentcontrol elements. Therefore, a solution must be found so that the data can be sharedby the different users. The two above–mentioned drawbacks can thus be obviated.

In summary, a DATABASE can be defined as a “common pool” of consistent data,shared by different programs.

This DATABASE concept covers two objectives: no data redundancy and dataconsistency.

How then are we to implement our DATABASE so as to bring it in line with the FMMand SSM concepts?

The data will to be stored in zones of the CE memory and/or on disks. If one FMMrequires a piece of data, it will only have to search for that piece of data in that place.The problem remains how the FMM calculates the physical address of the piece ofdata. This problem is resolved with the introduction of programs that handle the datadirectly. The function of these programs will consist of accepting data requests from theFMMs in the form of procedure calls (not through messages), localizing the specificpiece of data in that place and, giving the piece of data back to the user that requestedit.

This set of programs is called DATABASE CONTROL SYSTEM (DBCS).

As a result of the introduction of these programs, data independence is achieved withrespect to the data user programs. This increases the modularity and the futuresecurity of the data. Possible changes in the DATABASE itself will not have any effecton the programs that use it. Bearing in mind the “Virtual Machine” concept, it can bestated that the data and the DBCS that handle them form a virtual machine with respectto the data user FMMs.

Besides convenient data access, another basic database property is that of dataSECURITY, so that the data is protected against unauthorized access and also duringdangerous situations such as data copy or update. The system in charge of providingthis security is the DATA BASE SECURITY SYSTEM (DBSS), which is contained in thePeripheral & Load module.

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Figure 183 : Data Base overview

DATA

CONTROL SYSTEMDATA BASE

CE 1 CE 2 CE N

PROCESS 1 PROCESS N

b. A1000 S12 relational database

– Definitions.

The Database used by A1000 S12 has a relational structure, i.e. the data is organizedinto bi–dimensional tables called relations.

A RELATION is a bi–dimensional matrix where the rows are known as TUPLEs. Thetuples are divided into fields, called DOMAINs, which are the matrix columns. All thetuples in a relation have the same domains.

An example of a relation, i.e. a bi–dimensional representation of data, is shown in thenext figure.

In the relations, KEY is the name given to the domain or set of domains that uniquelyidentify a certain tuple. The different programs achieve the data access, always, bygetting one whole tuple.

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Figure 184 : Example of a relation

DOMAIN

TUPLE

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

ÏÏÏÏÏÏÏÏÏ

KEY

– Types of relations.

The database system distinguishes two types of relations according to whether therelations exist physically or only logically (such a relation exists only for the user):

1. REAL relations, are relations that are physically stored in memory or disk, as they have been defined. If a user requires a tuple, it will be presented as a whole.

2. VIRTUAL relations, are relations that do not physically exist but are supported by a set of real relations.

There are different types of virtual relations depending on how they are made up:

– REDEFINED.

– MULTITARGET.

– PROCEDURAL.

A REDEFINED VIRTUAL relation is supported by a single base relation and itsdomains are a subset of the base relation domains. The key of the redefined relationmust be the key of the base real relation.

Whenever a user asks for a tuple of a redefined relation, the DBCS will search for thetuple in the corresponding real relation. Only the subset of domains defined for theredefined relation, will be extracted and presented to the user. This new relation willhave a name different from that of the base real relation.

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Figure 185 : Redefined relation

REAL RELATION (ONLY ONE TUPLE REPRESENTED)

D_KEY D_1 D_2 D_3

R_1 A B C D

A D

D_KEY D_3

REDEFINED RELATION

(USER VIEW)

A MULTITARGET VIRTUAL relation is made up of domains of two or more realrelations. Of this set of relations, constituting a multitarget, one is the starting baserelation, the key domain of the multitarget relation being the same as that of the basereal. The joining with the rest of the relations that originate the virtual one, is performedthrough the common domains and by means of a JOIN operation.

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Figure 186 : Multitarget relation

JOIN

B C D

A B

A C D

D_1D_KEY

D_KEY D_1 D_2

D_KEY (R_1) D_1(R_2) D_2(R_2)

MULTITARGET

RELATION

REAL RELATION R_1

REAL RELATION R_2

(USER VIEW)

A PROCEDURAL VIRTUAL relation will be built up by a special procedure when theregular procedures provided by the database prove inadequate.

Obviously, the relation is not physically stored in memory and is based on one or morereal relations.

Whenever a user requires a tuple of a procedural relation, the DBCS calls theprocedure that searches for the requested information within the relevant real relations.This procedure will build the requested tuple and present it to the user that asked for it.

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Figure 187 : Procedural relation

A13 B12 N11

A12 A13A11

R_A

B12 B13B11

R_B

N12 N13N11

R_N

PROCEDURE

USER VIEW

A property common to all types of virtual relations is that it is absolutely necessary thatall the base relations are in the same control element as the FMM that requested thevirtual relation.

– Physical location of the relations.

A relation need not necessarily be stored entirely within one CE, nor does it have to bein a single CE. In other words, a relation may be split up and distributed among a set ofCEs, or copied entirely to more than one CE, or even both.

It is, however, also possible that neither of these two conditions are present; in thiscase the relation is called NORMAL.

A relation is said to be DISTRIBUTED when it is split up among a set of CEs. Each ofthese CEs has a set of tuples in storage depending on the value of one or more of therelation domains; these domains are called distribution domains. In this way only thatpart of the relation needed in the CE is loaded.

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Figure 188 : Distributed relation

DISTRIBUTION

USER

DBCS DBCS

DATA DATA DATA

BASEBASE BASE

CE_1 CE_2 CE_3

R_1

7

8

9

10

6

13

14

15

11

12

R_1

DBCS

R_1

1

2

3

4

5

A relation is called REPLICATED when there is an entire copy of the relation in severalCEs. One of the CEs, called master, will control the modifications of the relation tupleswhich is important to maintain the data consistency. A replication control procedure canfind which CEs contain a copy of the relation.

Figure 189 : Replicated relation

REPLICATION

USER

DBCS DBCS

DATA DATA DATA

BASEBASE BASE

CE_1 CE_2 CE_3

R_1 R_1

DBCS

R_1

1

2

3

4

5

1

2

3

4

5

1

2

3

4

5

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When both possibilities occur together, the result will be a DISTRIBUTED andREPLICATED relation. The distribution always taken place first, and then each of theparts into which the relation is divided, is replicated on a set of micros..

c. Communication between the user and the DBCS

In order for a user (FMM) to be able to obtain a piece of data from the database, it willhave to call an “interface” procedure that is a component of the DBCS. When the FMMcalls this procedure, a pointer (p) to a data area within the FMM is passed, as a callparameter, to the DBCS. This data area, that belongs to the FMM, is known as theUSER WORK AREA (UWA) and it is used as the communication area between thecalling process (user) and the DBCS.

Figure 190 : User – DBCS interface

FMMP UWA

R2

R3

RUWA

R1

ÉÉÉÉ

DB STATUS

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

DATA

DBCS

R1

R2

R3

In this FMM data area (the UWA), amongst others, the following main fields may befound:

1. DB_STATUS:This field will contain information about the result of the operation requested aftergetting back from the DBCS.

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2. RUWA:Relation User Work Area. In this area, one tuple for each of the relations that theFMM has access to, may be stored.

We will explain the way to make this communication effective with an example.

Let’s suppose that a FMM process (data user) requires to read a tuple of the relationR_1. The steps to follow are:

1. The call to access the data is done by the process to the DBCS. As said before, a pointer to the UWA is passed as a call parameter.

2. The DBCS is the system in charge of searching for the data in the data storage device (memory or disk) and of obtaining the requested relation tuple.

3. If the tuple is found, it is copied into the RUWA for the R_1 relation.

4. An indicator of satisfactory result of the operation will be written into the DB_STATUS field.

5. The control will be given back to the calling FMM process.

Figure 191 : UWA handling

UWA

DB_STATUS

RUWA

R_1

DBCS

DATA

R_1

FMM

GET R_1

D1 D2 D3 D4

D1 D2 D3 D4

1 CALL

5 RETURN

4 SET

DB_STATUS

3

COPYTUPLE

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d. Direct Access Relations

Even though the use of the DBCS for the access to the data stored in the database,has many advantages, it also has a great inconvenience that we cannot obviate: Thecalls to the DBCS take up execution time.

In order to reduce the time necessary to find the requested information, the users are,in some cases, allowed to access the database by themselves. To accomplish this, theusers look for the relation start address in the database only once, at the initializationtime. For the subsequent accesses, the users simply fetch the data directly from thedatabase, knowing the relation start position beforehand.

This type of access has an important restriction: it is valid only for read actions on realrelations . For the performance of relation modifications, it will be necessary to call theDBCS.

3.4.4 Device handler FMMs

The device handlers manage different devices depending on the module used:

a. Device handler in the ASM

In the ASM there are 128 subscribers (256 in X–over) and the ring circuits. They arehandled by the Subscriber Module Device Handler FMM (SMD) . The SMD is amonoprocess multidevice FMM with a separate data zone for each device. The task ofSMD is to manage the busy / free status of the devices.

In addition to the FMM there is an SSM. The SSM is called the Line Circuit, RingCircuit Device Handler SSM (LCRC DH SSM ). The SSM contains:

– clocked procedures and event handlers to scan the hardware for events;

– interface procedures to drive the hardware (hardware of the subscribers and theringing PBA).

b. Device handler in the ISM

In the ISM you find the same device handling software as in an ASM. The devicehandler can handle both analogue and ISDN subscribers.

c. Device handler in the DTM

In the DTM there are 31 trunks, which are looked after by the Trunk Circuit DeviceHandler FMM (TC DH FMM) . The TC DH is a monoprocess multidevice FMM (why ?).When a DTM is selected, and a trunk request enters, the TC DH selects a free trunkand marks it busy.

Also the TC DH FMM has an SSM counterpart to perform scanning and driving of thehardware: the Trunk Circuit Device Handler SSM (TC DH SSM) .

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d. Device handler in the SCM

In the SCM there are maximum 32 DTMF receivers . The FMM that manages thesedevices is called the Service Circuit Device Handler FMM (SC DH FMM) . The SC DHFMM is a monoprocess multidevice FMM.

The SC DH FMM is complemented with the Service Circuit Device Handler SSM (SCDH SSM). The SSM takes care of the driving of the senders and the scanning of thereceivers. It receives DTMF digits from subscribers and R1 or R2 information fromtrunks. It passes the digits one–by–one to the signalling subsystem.

3.4.5 Signalling system

In every access module the signalling is handled by a corresponding signalling system.

In the case of a subscriber module (ASM or ISM) and the trunk modules (DTM or IPTM), thesignalling system has quite a large number of functions. If these access modules have atleast 4 MB memory, the whole signalling system can be present in the access module. Ifhowever the access module only has 1 MB memory, the signalling system is split into twoparts:

� the terminal related functions are stored in the TCE (the access module);

� the call related functions are stored in an ACE. Typically this is the System ACE for CallServices (SCALSV).

a. Signalling system in the ASM

All subscriber events pass via the signalling FMM (line and register signalling).For each event signalling ”knows” (from a table) if call control should be notified or not.The signalling system is called the Analogue Subscriber Signalling System (ASSS) .Since the ASM only has 1 MB memory, ASSS is split into ASSS_TSIG (in the ASM)and ASSS_ASIG (in a SCALSV).

b. Signalling system in the ISM

The signalling system in the ISM is the ISDN Signalling System (ISS) . An ISM has 4MB memory, so the whole ISS is kept in this TCE.

Because of the CDE dependency of the ISDN signalling systems, ISS is implementedas a SBS. There are different entities for the different ISDN versions, but also differententities to handle the different layers in ISDN signalling.

c. Signalling system in the DTM

This signalling depends on the signalling used for the trunk (to which trunkgroup itbelongs). DTM signalling takes care of the line and register signalling between theexchanges. Here again you can have a split signalling system. Depending on thesignalling type, you have:

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– CAS_ASIG (in the SCALSV) and CAS_TSIG (in the DTM);

– ISUP_TUP_ASIG (in the SCALSV, handling both ISUP and TUP signalling) andISUP_TSIG, TUP_TSIG (in the DTM).

d. Signalling in the SCM

Here the Register Signalling SSM (RSIG SSM) collects the digits one–by–one fromthe SC DH SSM. Once a certain number of digits has been received, RSIG reportsthem to the requesting signalling system. The RSIG is always informed about therequested number of digits, so it knows when the digits should be transmitted in bunchtowards the requesting signalling system.

3.4.6 Call Control

� This plane contains Call and Facility Control System (CFCS) . CFCS is a multiprocessFMM.

CFCS handles:

– the basic call set–up for subscribers;

– the basic call set–up for trunks;

– supplementary services;

– the interface towards the SSF for IN services.

Whenever a call starts, the FMM is activated. Activation means the creation of an applicationprocess.

CFCS is implemented as a SBS:

� the shell is part of the application process.

� each entity has it’s specific task. Entities can be common or CDE. This depends on themain call control functions they logically belong to:

– basic call set–up: these entities are common;

– supplementary services: these enities are CDE;

– interface to IN: these entities are common.

3.4.7 Auxiliary Resources TCE Allocator

ARTA stands for Auxiliary Resource TCE Allocator. Resource means a DTMF receiver or anR2 sender / receiver.

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ARTA finds a Service Circuit Module that contains the correct receiver or sender and that isavailable. Its implemented as a monoprocess FMM and is located in the System ACE forCall Services.

The actual search for a SCM is performed by a procedural relation. This relation is consultedby ARTA. Figure 192 explains how the procedural relation works:

Figure 192 : ARTA procedural relation

1 SCM 1 AVAIL

2 SCM 2 UNAVAIL

3 SCM 3 UNAVAIL

4 SCM 4 AVAIL

5 SCM 5 AVAIL

6 SCM 6 AVAIL

4 SCM 4 AVAIL

RUWA

ARTA

Procedural Relation

5

2

INDEXa

b

c

d

Following steps are taken in the procedural relation :

[ a ]The index is used to select a tuple from the relation.

[ b ]Starting from this index, a sequential search is done until an SCM with the statusAVAILABLE is found.

[ c ]The tuple is copied to the RUWA of the ARTA FMM.

[ d ]The index is updated to make sure that the next search starts with the next SCM in thelist.

Then we return from the procedural relation.

3.4.8 Analysis of the Called Party Digits

Based upon the received digits, the destination of the call has to be defined. This is done byan FMM, called PATED (Prefix Analysis and Task Element Definition).

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PATED consists of two functional parts

� Prefix Analysis. This part provides a digit preparation and analysis, resulting in a

Condensed Prefix (CPX), a Cause or a request for more digits. The CPX is a number assigned to all digit combinations which result in a common set oftasks : all subscribers connected locally, which must be charged in the same way have asame CPX, while all digit combinations leading to the selection of the same outgoingroute (for outgoing calls) have another CPX assigned to it.A cause is a number indicating which faulty situation occurred. The cause value found byPATED could for instance be a value indicating ’DN Not Assigned’.In the case of a CPX or a Cause, the result is passed to the second part for furtheranalysis. In the case of a request for more digits, a message is sent back to CFCS to receive moredigits from the originating side.

� Task Element Definition. This part receives the result from the previous part (CPX orCause) and retrieves information about the tasks to be executed to complete the call.These tasks are : destination information, charging parameters, restrictions, numberingtype and signalling information.These tasks not only depend on the received digits (CPX), but some of them are also afunction of the time of day, the type of call (normal call, operator call,...) or the origin of thecall (subscriber, incoming trunk,...).

Figure 193 gives an overview of the structure of PATED. We will describe the differentblocks in greater detail.

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Figure 193 : PATED Structure

CategoryAnalysis

Digit preparation

Digit Analysis

Received digits

Type of call

Origin OriginAnalysis

TimeAnalysis

TaskElementDefinition

CPX

CAUSE

Request more digits

&

Time

ÉÉÉÉÉÉ

ÉÉÉÉÉÉ

Tasks

Prefix Analysis Task Element Definition

a. Category Analysis

Here, the Type of call is analysed. Possibilities are : Operator call, Data call, Test call,normal call, priority call,...The result of this analysis serves as input for the Task Element Definition and for theDigit Preparation.

b. Origin Analysis

In this block the origin of the call is defined. This origin is a combination of :

– Type of Numbering Plan (telephone, telex, private numbering plan,...)

– Nature of Address : The Nature of Address specifies the layout of the received digitstream (International, National, Network Specific,...). This value indicates whetheror not the country code is inserted in the received digit stream, whether or not thetrunk code is inserted ... .

– SourceCode : Defines the type of originating equipment (Subscriber, trunk, test

equipment,...) and the group (subscriber group , trunkgroup,...) to which theoriginating device belongs.

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The result of this analysis serves as input for the Task Element Definition and for theDigit Preparation & Analysis.

c. Time Analysis

Here, the time of day is analysed. This analysis result serves as input for the TaskElement Definition block.

d. Digit Preparation

The function of digit preparation is to adapt the layout of the received digit stream to astandard digit stream layout, used inside the exchange.

Example :

Suppose the standard layout in the exchange is :

0 P Q A B C D E ...

Where P Q = The zone prefix

A B C = The exchange prefix

D E ... = The subscriber identity inside the exchange

If the received digit stream has layout A B C D E..., digits 0 P Q have to be insertedbefore the A.

The digit preparation depends on

– The received digits

– The type of call

– The origin of the call (Source code + nature of address + Numbering plan indicator)

Figure 194 gives an overview of the digit preparation.

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Figure 194 : Digit preparation

Digit

Preparation

Received digit stream

Adapteddigit stream

Origin

Type of call

Received digits Origin Type of call Adapted digit streamSourcecode Nataddr. Numb. plan

0 P Q A B C D E ... 0 P Q A B C D E ...

0 P Q A B C D E ...

0 P Q A B C D E ...

0 P Q A B C D E ...

Subscr

Subscr

E164

E164

E164

E164

Incoming

Incoming

unknown

unknownA B C D E ...

P Q A B C D E ...

I1 I2 I3 P Q A B C D E ...

Normal Call

Normal Call

Normal Call

Normal Call

... ... ... ... ... ...

National

Internat.

e. Digit Analysis

In this block the received digits are analysed to define the destination and the tasks tobe executed to reach that destination. For the analysis of the digits, we use a treestructure. Figure 195 shows the layout of this tree. Each element of the tree contains16 entries. The first digit, D1 is used as an index in the first element. Here we find apointer to a next element. Now we use the second digit, D2 as index in this newelement. Again we will find a pointer to a new element.We will continue with this algorithm, each time using the next received digit (D3, D4,...),until we find an indication that the prefix has been analysed. In the last entry we willfind a Condensed Prefix (CPX) or a CAUSE. This result is now passed to the lastblock, the Task Element Definition.

The result of digit analysis not only depends on the received digits, but also on theorigin of the call. This is implemented by making the entry point in the tree structureorigin dependent. In the block Origin Analysis, we will find the entry point in the treestructure. From this entry point on, we will start analysing the received digits. Thisimplies that for another origin, we will follow a completely different branch in the treeand so the final result will be different.

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Figure 195 : PATED Tree structure

...

...

...

...

...

...

...

...

...

...

...

...

...

...

D1

D2

D3

01

15

Digit AnalysisResult

(CPX or CAUSE)

Origin

Analysis

Numbering planindicator

Nature of address

SourceCode

f. Task Element Definition

This block defines the tasks that have to be executed to reach the desired destination.

Most tasks depend not only on the Analysis result (CPX),, but also on the origin, thetype of call and even the time of day. Therefore the outputs of all 4 blocks of the prefixanalysis part (see figure 196) serve as input for this Task Element Definition block.

The most important information we find here includes :

– Do we have a terminating or an outgoing call

– Do we have open numbering or closed numbering. What is the length of thenumber.

– Is it a priority call or not

– If we have an outgoing call, after how many digits do we start trunk selection

– ...

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Type of call Extra Information

LOCAL DNET of Called Subscriber

OUTGOING Routecode , start selection point, ...

So far, we have only discussed the successful analysis of an existing prefix. Now let ussee what happens if something goes wrong.

– We did not receive enough digits (yet) to find a Condensed prefix. Suppose we received 3 digits from the originating device. After having analysed thethird digit, we still have not found a CPX. In that case, PATED will send a messageback to Call Control, asking for one or more digits. After having received somemore digits, Call Control will send all digits back to PATED, where digit analysiscontinues.

REMARK: The number of digits, which is sent to PATED, is always greater than or

equal to the number of requested digits retrieved from OLCOS . For example: anISDN subscriber provides all the called digits in one message, so all the digits aretransmitted to PATED and there will not be a request for more digits.

– Another possibility is that the received number does not exist. Instead of finding acondensed prefix (CPX), the digit analysis output will give us a CAUSE. Now we willhave to find out what we have to do to end the call properly (e.g. It will tell us that wehave to send a congestion tone to the calling subscriber.)This is done by the same Task Element Definition block. This time we will send theCAUSE value instead of the CPX to the Task Element Definition. Now we will find alist of tasks that have to be executed to end the call. Just as in the normal case,these tasks are also a function of the Origin, Type of Call and Time of day.

– This feature of PATED is also useful if we find other problems during the callhandling. (e.g. we can not find a free DTMF receiver, A timer expires, a Q931protocol error is detected,...)Each possible problem is identified with a CAUSE value. When such a problemoccurs, we will send the corresponding CAUSE value to PATED. In PATED, theDigit Analysis step is skipped and we jump immediately to the Task ElementDefinition step. Here, too, we find a list of tasks to solve the problem.

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Figure 196 : PATED for CAUSE analysis

CategoryAnalysis

Digit preparation

Digit Analysis

Type of call

Origin OriginAnalysis

TimeAnalysis

&


CAUSE

Time

ÉÉÉÉÉÉ

ÉÉÉÉÉÉ

Tasks


3.4.9 Subscriber analysis

a. Subscriber data in general

During a call a lot of information about subscribers is needed. Some of the data isrequired to set up the call, other information describes the facilities that a subscribermay have. Since the amount of data is so big, the data is stored in two locations:

– the data that is required to set up the call is stored in the subscriber’s TCE itself. Wecall this the subscriber data at TCE level. The data is retrieved by the device handlerFMMs and the signalling FMMs;

– the rest of the subscriber data, including possible facility data, is stored in an ACE.

This ACE contains both the originating and the terminating profiles . The FMMthat retrieves all the subscriber data in the ACE is the Local SubscriberIdentification (LSIF) FMM. We therefore talk about the subscriber data at LSIFlevel.

The ACE that is mentioned here is the SACELSIF. Please refer to chapter 4.2.4..c formore information on this ACE. At this moment it is important to know a little about theconfiguration of this ACE.

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The SACELSIF works in an active / stand–by configuration. The amount of subscribersa SACELSIF can handle is limited. So in a medium, and certainly in a large exchangethere will be a number of these SACELSIF pairs. The problem then of course is toknow which one of these pairs to choose when the subscriber data at LSIF level isrequired. The directory number equivalent thousands (DNET) of the subscriber thatis anlysed, is used for that purpose. This applies to both an originating subscriber, as toa terminating subscriber.

First let us have a look at the subscriber data itself. Figure 197 shows the organisationand location of the subscriber data.

Figure 197 : Subscriber Data location

DNE analysis facility_1

facility_2

COL

OLCOS

COS

TCE level

LSIF level

DNE

The next chapters describe these data blocks one by one.

b. Class Of Line (COL)

The COL gives information about the physical line that is connected to the exchange.For an analogue subscriber it indicates amongst others:

– the settings of the hybrid on the ALCN board;

– the type of set (push button set, dial pulse set, combined set);

– whether a hardware key is used on the set.

c. Originating Line Class of Service (OLCOS)

This is the data we need when a subscriber originates a call. The OLCOS data is thebare minimum data to set up a call. The most important fields of this OLCOS are:

– the terminal number or data key. This is the index into this data;

– the directory number equivalent (DNE). Such a DNE consists of the directory

number equivalent thousands (DNET) and the directory number equivalent units

(DNEU) ;

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– if the tuple represents a subscriber’s line, the equipment number (EN) is given. TheEN consists of the LCE identity of the TCE and the terminal number or datakey;

– if the line belongs to a PABX, the PABX identity is given;

– the tone map, that indicates which dial tone to apply.

d. DNE analysis

The DNE analysis indicates:

� the type of directory number (DN). Some possibilities are:

– not assigned number;

– normal subscriber line;

– Multi–Subscriber Number (MSN);

– Direct Dialling–In Extension (DDI–Ext).

– depending on the type of DN, further information is given:

– if the DN represents a single subscriber line, the equipment number (EN) is given. The EN consists of the LCE identity of the TCE and the terminal number or datakey;

– if the DN represents a line of a PABX, the PABX identity is given.

e. Class Of Service (COS)

The COS data gives information about both public subscribers (analogue and ISDN)and BCG subscribers.

The COS data contains both the originating COS data and the terminating COS data.

f. Facility data

The data that describes the different facilities is stored in separate relations. As anexample there is a relation that holds the abbreviated dialling information, an otherrelation that holds the call forwarding information, and so on.

If a subscriber does not have any facilities, no tuple out of these relations are allocatedto this subscriber.

If an operator assigns a facility to a subscriber, a tuple from the relation that describesthat facility is allocated to the subscriber. The tuple is then linked to the subscriber’sCOS data. If a second facility is assigned, a tuple from an other relation is allocatedand linked to the COS data as well. The COS data and the facility data thus form achained structure. The reason for implementing the facility data in a chained structure,

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is that you only have to use a tuple of a particular facility relation if the subscriber hasthat facility.

In the example of figure 197 the subscriber appears to have two facilities.

g. Retrieval of data for originating subscribers

To describe the subscriber data in detail and how it is retrieved, let us have a look at anexample. Let us assume closed numbering with seven digits. Let us call the digitsD1D2D3D4D5D6D7. Figure 198 indicates how the DN can be broken up into the DNET,the DNEU and the DNEH.

Figure 198 : DNET, DNEU and DNEH

D1 D2 D3 D4 D5 D6 D7

DNET

DNEU

DNEH

Figure 199 gives an overview of the subscriber data structure.

Figure 199 : Subscriber data in detail

DNET

DNEU

TN or DK

formula

D5

D6D7

COS linkchain

COS

facility_1

facility_2

TCE level LSIF level

DNEHanalysis

00

99

00

99

DN analysis

DNEH

blockof100

tuples

OLCOS

The subscriber data is retrieved in the following sequence:

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[ 1 ]The OLCOS data is retrieved in the TCE. The key to this data is the terminal number(TN) or the data key (DK). The DNET is amongst others used in the SCALSV to findthe correct SACELSIF.

Note : An analogue subscriber can only have one profile stored at TCE–level in R_OLCOS; thatprofile is stored against the TN. An ISDN BA can have up to 8 MSN’s assigned to the same access,thus to the same TN, and for each of these MSN’s, a separate profile can be stored. For each MSN,a tuple has to be stored in R_OLCOS. At TCE–level, a specific procedural relation, called theSCREENING PROCEDURE, will translate the TN and MSN in a new parameter called the DataKey(DK), which is used as a key in R_OLCOS.

[ 2 ]In the SACELSIF the first action is to find the directory number equivalent hundreds(DNEH). The DNEH is calculated with a formula: DNEH = (DNET – 1) * 10 + D5 + 1.

[ 3 ]The DNEH is then analysed. The DNEH can represent:

– a block of 100 DNs for normal subscribers;

– a block of 100 DNs reserved for an indialling PABX;

– an unused block of 100 tuples.

If we assume that the DNEH represents a block of 100 DNs for normal subscribers,then the DNEH analysis gives a link into the DN analysis block.

[ 4 ]To find the correct entry in the DN analysis block, you have to take the link as providedby the DNEH analysis and increment it with the last two digits of the DN (D6D7, in therange of 0 to 99). The DN analysis gives the information as presented in chapter d.This includes the type of DN and further information. If we assume a single subscriberline, the ’further information’ also contains a link to the COS link chain.

[ 5 ]The COS link chain always contains at least one link: the link to the COS. This data isalways required. If the subscriber has facilities, then further links can link all theadditional tuples (in different relations) together.

[ 6 ]The COS data was described in chapter e. The facility data was described in chapter f.

h. Retrieval of data for terminating subscribers

In the case of a terminating call, PATED gives us:

– an indication that it is a terminating call;

– the DNET value of the terminating subscriber. This value was derived during digitanalysis.

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In CFCS, we collect the remaining digits (D5, D6 and D7) from signalling. We use theDNET value to find the appropriate SACELSIF and send a request to LSIF to startsubscriber identification. As in figure 201 LSIF retrieves the EN of the terminatingsubscriber, together with the subscriber data. With the EN we have know the locationof the B–party.

i. Restriction match

In the case of a terminating call, LSIF has to examine if the call is allowed to continue.This check is called the restriction match. Figure 200 shows how it is implemented.

Figure 200 : Restriction match

CAUSE CAUSE CAUSE

CallingPartyCategory

Access Status

– No CAUSE– Destination restricted

normal line operator linecoinboxdataline

normal call

priority call

operator call

testcall

There is a restriction match table. We select a row using the Calling Party Category

(CPC) as index. For originating calls, the CPC comes from the COS data. Forincoming calls, the CPC value is retrieved from the remote exchange via signalling(sent from the remote exchange as a Type Of Call (TOC)).In the selected row, we use the access status as index to pick out one element. Theaccess status was retrieved from the TLCOS. The value in the selected element tellsus if the call is allowed (no Cause) or not (destination restricted).

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Figure 201 : LSIF

RETRIEVAL OF OLCOS

RETRIEVAL OF TLCOS

Restriction Match

PATED

OLCOS

LSIF

DNET,DNEU

DNET

CALLING PARTY CATEGORY

Prefix Digits

OK/ NOK

DNEU

originating subscriber

terminating subscriber

3.4.10 Trunk Search

Figure gives an example of (a part of) a network. Suppose that a subscriber from exchangeA wants to call a subscriber from exchange D. In the following chapters you find a number ofdefinitions that are used in the routing of this call.

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Figure 202 : Routingblock – Route

Exch A

Exch B

Exch C

Exch D

a. Trunk

A trunk corresponds with one channel of a PCM link. A trunk is bi–directional. To avoidthat the exchanges at either side of the trunk try to seize the trunk simultaneously, twopossibilities exist:

– you can declare some of the trunks as outgoing and the rest of the trunks asincoming. The fact whether a trunk is outgoing or incoming only reflects whichexchange can seize the trunk: an exchange can only seize the outgoing trunks. As aresult, the trunks that are declared as outgoing in one exchange, have to bedeclared as incoming in the exchange at the other end of the PCM link and viceversa.

– you can also declare the trunks as bothway trunks. In this case both exchanges canseize the trunk. In this case the possibility of a collision exists. The software thenhas to solve the problem.

Every trunk has to be handled by a particular signalling system. This way the seizureand all the other events of the trunk can be reported to the exchange at the other sideof the trunk, but also the digit information can be reported.

Note : Let us abbreviate trunk to TK.

b. Trunkgroup

Trunks that have the same characteristics can be grouped into a trunkgroup. Typically”the same characteristics” means:

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– interconnecting the same exchanges;

– having the same direction (outgoing, incoming or bothway);

– using the same signalling system (for example MFC, CCS N7).

Figure 203 : trunkgroups – Trunks

DTM 2

DTM 1

DTM 2

DTM 1

Trunkgroup AB1R2 trunks

30 trunks

30 trunks

Exch A Exch B

IPTM 2 IPTM 230 trunks

DTM 3 DTM 331 trunks

IPTM 1 IPTM 130 trunks

Trunkgroup AB2Nr7 trunks

In figure 203 exchange A is connected to exchange B with 5 PCM links. There are twotrunkgroups: trunkgroup AB1, with R2 trunks and trunkgroup AB2 with CCS N7 trunks.

The equipment number of a trunk consists of the LCE identity of the trunk module +the channel number, or the trunkgroup identity and the trunk sequence number.In the figure, trunkgroup AB1 contains 60 trunks, spread over 2 DTMs, while trunkgroupAB2 contains 91 trunks, spread over 2 IPTMs and one DTM.

Note : Let us abbreviate trunkgroup to TKG.

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c. Route

The collection of all the trunkgroups between two exchanges is called a route. Atpresent this definition is primarily used for administrative and traffic managementpurposes.

d. Trunkgroup combination

At present subscribers can demand a certain minimum bearer capability of thenetwork. Possible bearer capabilities are:

– speech;

– 3.1 kHz audio;

– 64 kb/s unrestricted digital.

In addition, if the subscriber has activated certain facilities, possibly a minimumsignalling dependency is also required. Possible signalling dependencies are:

– any;

– digital mandatory;

– ISDN signalling preferred;

– ISDN signalling mandatory;

– ISUP signalling mandatory.

Hence, when a call is outgoing and a trunk has to be selected, it is possible that not allthe trunkgroups can be used, if they do not support the minimum bearer capability orsignalling dependency. Therefor a restriction has to be built in to the trunk searchmechanism. Observe the following figure.

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Figure 204 : Definition of trunkgroup combination lists and trunkgroup combinations

BC Sign. System

Speech , AudioDigital

any

digital signalling

ISUP preferred

ISUP mandatory

Speech , AudioDigitalSpeech , AudioDigitalSpeech , AudioDigital

any

digital signalling

ISUP preferred

ISUP mandatory

ISUP

R2

Analogue transmissionISUP

Analogue transmission

Exch A

Exch C

Exch B

2

3

4

5

6

1

Digital transmission123 Analogue transmission

TUP

456

ISUP

R2 Analogue transmission

Digital transmission

tkgcom AC1

tkgcom AC2

tkgcom AC3

tkgcom AB3

tkgcom AB1

tkgcom AB2

trunkgroup Characteristics

trunkgroup Characteristics

Routingblock to Exchange B :

Route AB Route AC

tkgcom AB1

tkgcom AB1

tkgcom AB1

tkgcom AB1

tkgcom AC1

tkgcom AC1

tkgcom AC1

tkgcom AC1

tkgcom AB3

tkgcom AB2

tkgcom AB2

tkgcom AB1

tkgcom AC2

tkgcom AC2

tkgcom AC2

tkgcom AC3

subrouteblock

subroutingblock 1

subroutingblock 2

subroutingblock 3

subroutingblock 4

subroutingblock 2subroutingblock 1

subroutingblock 1

subroutingblock1

trunkgroups

In the route AB there are three trunkgroups:

– trunkgroup 1 (ISUP signalling);

– trunkgroup 2 (TUP signalling);

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– trunkgroup 3 (R2 signalling).

Suppose that you need a trunk from exchange A to exchange B. If a bearer capabilityof digital and a signalling dependency of ISUP mandatory is requested, then only atrunk of trunkgroup 1 can be selected. If however a bearer capability of speech and asignalling dependency of ISDN preferred is requested, then both trunkgroups 1 and 2comply.

So based on the required bearer capability and signalling dependency, a subset of thetrunkgroups from a route can be declared. This subset is called a trunkgroupcombination.

Note : Let us abbreviate trunkgroup combination to TKGCOM.

e. Subroutingblock

In figure 205 you can see three exchanges. For a particular call from exchange A itmay be possible that both a trunk via exchange B or a trunk via exchange C can beselected. The collection of trunkgroup combinations that lead to the correct destinationis called a subroutingblock.

The definition of a subroutingblock is important for the routing of a call, since it onlycontains trunks that (eventually) lead to the correct destination. The definition of asubroutingblock also guarantees that it only contains trunks that comply with aparticular bearer capability and a signalling dependency.

Note : Let us abbreviate subroutingblock to SRTGBL.

f. Routingblock

The collection of all the trunkgroups that (possibly) lead to the correct destination, iscalled a routingblock. This destination does not have to be an adjacent exchange.

Note : Remark that the definition of a routingblock does not indicate any dependency. It onlyindicates the routing of a call.

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Figure 205 : Routingblock – Route

Exch A

Exch B

Exch C

Exch D

Route AB

Route AC

RoutingBlock Destination Routes

1

2

3

Exch B

Exch C

Exch D

Route AB Route AC

Route ABRoute AC

Route AB Route AC

+

+

+

In Exchange A :

The table in figure 205 gives an overview of all the routingblocks, defined in exchangeA. We see that exchange A is not connected to exchange D, yet we define aroutingblock to that exchange D (routingblock 3). If we want to set up a call toexchange D, we can select route AB or route AC, because exchange D is reachablethrough exchange B or exchange C.

A routingblock is identified with a routingcode. For outgoing calls, PATED translatesthe dialled digits into a routingcode, which is used to select a free trunk to reach thecorrect exchange.

When PATED gives a routingcode, the restrictions for bearer capability and signallingdependency have to be built in. We call this the routingcode modulation . The result isa subroutingblock.

Note : Let us abbreviate routingblock to RTGBL.

g. Trunkgroup combination list

In the previous chapters we collected the trunkgroup combinations that lead to thesame destination into a subroutingblock. If you require traffic distribution over thetrunkgroup combinations is required, or if you require overflow possibilities, you can

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define a step in between the subroutingblock and the trunkgroup combinations: thetrunkgroup combination list. Observe the following example:

Figure 206 : Example of trunkgroup combination lists

overflow choice

Exch A

Exch B

Exch C

Exch D

Exch E

first choice

Exch F

50%

30%

20%

50%

50%

The first choice is via exchanges B, C or D, with a respective traffic distribution of 50%,30% and 20%. The overflow choice is via exchanges E or F, with a traffic distribution of50% and 50%. The result is the following hierarchy:

Note : Let us abbreviate trunkgroup combination list to TKGCOML.

Figure 207 : Routing hierarchy with trunkgroup combination lists

TKGCOM_1 TKGCOM_2 TKGCOM_3 TKGCOM_4 TKGCOM_5

TKGCOML_1 TKGCOML_2

SRTGBLfirst choice overflow choice

50% 30% 20% 50% 50%

Trunkgroup combination lists are optional in the routing hierarchy !

h. Distribution group

If in a country several carriers operate the telephone network, it is possible that toreach a certain destination, the traffic has to be distributed between these carriers.These carriers have defined complete subroutingblocks. As a result the traffic

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distribution has to be defined between the routingblock (indication of the destination)and the subroutingblocks.

Therefore distribution groups have been defined. A distribution group contains anumber of subroutingblocks, each corresponding with a particular carrier, and indicatesthe traffic distribution values between them.

Distribution groups are optional in the routing hierarchy !

Note : Let us abbreviate distribution group to DISTRG

i. Routing hierarchy

Figure 208 : Routing hierarchy

RTGBL

SUBRTGBL

TKGCOML

TKGCOM

TKG

TK

ROUTE

DISTRG

Y

N

tkgcoml

distrg

needed?

needed?

Y

N

j. FMMs involved

There are three FMMs involved in the selection of a trunk.

– Trunk Request Coordinator (TRC) : responsible for the routingcode modulation, theselection of a trunkgroup combination and the selection of a trunkgroup within thattrunkgroup combination. The selected trunkgroup identity is sent to the next FMM,

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the Trunk Resource Allocator (TRA). The TRC is located in the same CE as CFCS,i.e. in each SCALSV.

– Trunk Resource Allocator (TRA) : selects a DTM with free trunks belonging to therequested trunkgroup. The LCE–Identity of the selected DTM is sent back to CFCS.Also the Device Interworking Data is retrieved here (see figure 209). All TRA’s in anon–line exchange are located in dedicated CE’s called SACETRA.

– The Trunk Circuit Device Handler (TC DH FMM) : selects a free trunk belonging tothe requested trunkgroup and establishes a UCP towards the DH of the incomingside (SMD FMM or TC DH FMM)

Figure 209 : Trunk selection

PATED CFCS

TRC

TRA

BCPrefix

Routingcode Sign.Type

DTM–id

DID–data

REMARK: The inputs indicate information, so these arrows are no messages.

TrunkgroupcombinationTrunk group

3.4.11 Device Interworking Data

Apart from the selection of a free and compatible trunk, another very important task remains

to be done : retrieval of the Device Interworking Data (DID) .

The DID is a task map describing all necessary tasks to connect the originating device(calling subscriber or incoming trunk) to the selected terminating device (outgoing trunk orterminating subscriber).

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The originating device is identified by the subscriber group identity in the case of anoriginating subscriber or by the trunkgroup number in the case of an incoming call.

The data is retrieved by the TRA FMM and sent back to CFCS.

The Device Interworking Data are subdivided into:

� incoming tasks : these tasks are executed by the incoming signalling. Examples:

– new value for inter–digit time–out;

– send a call–in–progress tone to the incoming device.

� outgoing tasks : these tasks are executed by the outgoing signalling. Examples:

– digit forward sending point;

– digit preparation;

– calling line identification restriction;

– moment of through connection (upon address complete, upon answer,...).

� common tasks : these comprise additional tasks or call control. Examples:

– perform charging or not.

3.4.12 Private Access Resource Management (PARM)

So far, we have discussed two types of called devices :

� Subscriber lines : In this case LSIF is called to translate the called DN into the EN of thecalled subscriber.

� Outgoing trunks : Here, we call the Trunk Search FMMs is called to select an outgoingtrunk to the correct destination.

In this chapter we will discuss a third type of called device : The Private Automatic Branch

Exchange (PABX).

A PABX is a switching network, located on the customer’s premises, serving a number ofextensions. It is connected to the public exchange by means of a number of lines (Analogueor BA) and/or a number of trunk connections (Analogue trunks, Digital CAS–trunks orPRAs).

Figure 210 gives an overview of a few PABX types.

� PABX without indialling : The PABX is identified by means of the General Directory

Number (GDN) . For a call to this GDN, we have to select a free access towards the

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PABX. The process of selecting a free access is called hunting. Inside the PABX, the

call is routed to an attendant . This person is responsible for routing assistance. Theattendant can establish a further through connection between the incoming call and the

desired PABX extension . The extensions are invisible to the public exchange.

� PABX with indialling : In such a PABX, the extensions can be reached immediately fromthe public exchange. Apart from the GDN, we assign a DDI range (Direct Dialling In

range) to the PABX. In the figure the DDI range is from 00 to 99. Each numberinside this DDI range corresponds to one extension.To identify an extension in the public network, we take a Prefix value, assigned to thePABX, in combination with the extension number. In the example the PABX prefix is24037. To reach extension 69, the DN = 2403769 has to be dialled.The signalling towards the PABX must contain at least the dialled extension number. Thisis used to establish a connection inside the PABX towards the correct extension.In the public exchange, hunting is based on the dialled prefix, not on the GDN. In such acase the GDN is only needed to uniquely identify the PABX.

� Hunt group : We can also group a number of individual lines into a hunt group. Thishunt group is also identified via a GDN. A call towards this GDN will give a hunting overthe lines.

Each line is also assigned an individual DN (IDN) . A call towards this individual DN isalso possible, but in this case no hunting is involved.

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Figure 210 : PABX types

PABX

(GDN = 2403600)

Hunting on GDN

Call routedto attendant

PABX without indialling :

PABX with indialling :

Hunting on prefix 24037

Call routed to extension

.

.

.

Hunting on GDN = 2403800

IDN1 = 2403801

IDN2 = 2404523

IDN3 = 240 2534

PABX

(GDN = 2403700)

.

.

.

Huntgroup :

00

01

99

02

Attendant

Attendant

In System 12, the Private Access Resource Manager (PARM) is responsible for the huntingprocess and the class provision of PABXs or hunt groups. PARM is located in a dedicatedSystem ACE, working in Active/Standby mode. Following tasks have to be executed :

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a. Class provision

All classes (originating as well as terminating) of PABXs, hunt groups or citylines are stored in the system ACE where PARM is located. PARM is responsible for theretrieval of these classes for originating and terminating calls. Figure 213 shows theretrieval of classes.

Figure 211 : Class provision

A. Originating calls.

B. Terminating Calls.

Prefixdigits PATED LSIF PARM

Remainingdigits

DNET PABX–Id

TN OLCOS LSIF PARMDNET,DNEU PABX–Id

Originating classes

Terminating classesRestriction match

b. Hunting

In the case of a terminating call towards a PABX or hunt group, PARM selects a freeaccess towards the PABX. Figure 214 gives an overview.

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Figure 212 : Hunting

Hunt Id. (Derived from PABX–Id)

Hunt group Modulation

BC

Signalling SystemReduced Hunting

LineGroup TrunkGroup

DTM–IdENEN DTM–Id

HuntingSubgroup block



First of all, the Hunt Identity has to be defined. This hunt identity is derived from thePABX identity. It can be compared with a RouteCode identity in the case of trunksearch (see TRC–TRA). The hunt identity defines a HuntGroupBlock.

Each Hunt group block is further subdivided into Hunting Subgroup blocks. Theselection of a subgroup block depends on :

– The Hunt Identity

– The required Bearer Capability

– The required signalling system

– A Reduced Hunting indication. In the case of reduced hunting, we will only selectfree accesses from a subset of all available accesses. This can be useful during lowtraffic periods, when only a few lines of a hunt group are being served.

This selection process is almost identical to the Route code Modulation used in TrunkSearch.

Each hunting subgroup block consists of a number of line groups and/or trunkgroups.A line group consists of a number of individual lines (analogue or BA) having the samecharacteristics. A trunkgroup was already been defined in the chapter on trunk search.

In the case of a line group, the hunting procedure will select a free line belonging to thatgroup. This line is identified by its EN.

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In the case of a trunkgroup, PARM selects a DTM with free trunks belonging to theselected trunkgroup. The selection of a free trunk within this DTM is left to the TC DHFMM.

c. Queue service

If all accesses towards a PABX or hunt group are busy, it is possible exists to queue acall until an access becomes free. This process of queuing is done by the PARM FMM.Whenever a line or trunk towards a PABX/hunt group becomes free, the DH informsPARM. Here, the queue is checked. If there is a call on the queue, it will be offered tothis access.

3.4.13 Physical mapping of the software onto control elements

Figure 213 : Physical mapping of the software onto control elements

CFCS

ASSS_ASIG

ASSS_TSIG

ARTAPATED

SMD FMM

LCRC DH SSM

SCALSV

TRA

LSIF

SACELSIF

SC DH SSM

SC DH FMM

RSIG

SCMASM

TC DH FMM

TC DH SSM

DTM

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

HARDWARE

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

HARDWARE

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

HARDWARE

... _TSIG

... _ASIG

TRC

SACETRA

SMD FMM

LCRC DH SSM

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

HARDWARE

ISM

ISSS

PARM

SACEPBX

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4. 1000 S12 EXCHANGE CONFIGURATION

4.1 Input/Output exchange devices

From the administrator point of view, access to Alcatel 1000 S12 is provided by a set of I/Ointerfaces which provide a set of tools to maintain and operate the exchange. Thisadministration device can be split into the following two groups: Man–MachineCommunication and Mass Storage.

The Man–Machine communication (MMC) devices are basically VDUs and printers. TheVDUs can be system specific VDUs or PCs on which VDU simulation programs areexecuted. Their main objective is to control the whole exchange by entering the properorders (Operator Request Jobs). Both VDUs and printers are used to dump autonomoussystem reports and ORJ reply reports.

These devices are connected to the P&L modules by serial channels – 1200 b/s using theDMCA PBA or, 9600 b/s using the MMCA PBA–. After the activation procedure, each ofthese connections is named ’MMC channel’.

Figure 214 : Man Machine Communication devices

PRINTERS

EXCHANGE

VDU & PCs

Serial Lines

On the other hand, there are also mass storage devices. These devices are used to storethe software and the data of the exchange as well as statistical and charging data which arevery useful for the administration of the exchange. It is important to note that the size of theexchange is sometimes small and the quantity of required data large. In such cases, the newdata is transmitted to a remote center (NSC, EDPC..), where it is processed.

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The mass storage devices are mainly the Magnetic Tape Unit, the Magnetic Disk and theOptical Disk.

The Magnetic Tape is the most commonly used device with large capacity and sequentialaccess. The digital recording is carried out by using a plastic tape covered with a layer ofmagnetic liquid. This magnetic tape is moved by two reels and the data is read/written by aR/W head.

On the other hand, magnetic disk memories are large capacity memories with a lower costthan random access memories. A disk is made of metal coated with a ferromagneticmaterial, and rotating under one or more read/write heads. The reading and writing principleis the same as for magnetic tape.

These hard disks have an embedded controller that performs all address calculating andaddress translating functions, as well as driving functions of the hard disk. To the outsideworld, the hard disk looks like a SCSI device. The hard disks support re–selection, whichmeans that they can act as an initiator in an SCSI environment.

The re–writable optical disk combines the advantages of two capacity worlds: the mediumand the high. It ranges in the order of 600 MB. The information carrying medium of an opticaldisk is a 5.25” cassette that contains a compact disk (CD). This CD consists of an alloy oftransition and rare–earth materials. The alloy can be magnetized only when it is hot, but itkeeps its magnetic field when it is cool.

Therefore, the writing principle of the optical disk consists of a laser heating up the spot tobe written just before the head of the optical disk writes the information in a magnetic way.The reading is based on the laser scanning the disk’s surface and detecting any differencein the angle of reflection caused by upward or downward pointing magnetic fields. So theread write principle of the optical disk is in fact a magneto–optical principle.

The optical disk used in A100S12 is equipped with an embedded SCSI controller. Thiscontroller handles all the driving functions for the optical disk, and makes it look like anordinary SCSI device to the outside world. The most common specifications of optical diskare 652 MB of capacity and 1.4 MB per seconds as transfer rate (at SCSI interface).

This optical disk might be used as system disk instead of the magnetic disk, but it presentstwo problems at the moment: first, the writing/reading operations are performed in asequential way, therefore the data access time is slower than for the magnetic disk, andsecond, the writing towards the optical disk is limited.

There are other special I/O devices such as MPTMON (Multi–processor Test Monitor) .This terminal is mainly used for integration tests, although it is also useful for other purposessuch as installation and maintenance.

It may be a specific VDU or one PC running the suitable simulation program. In any case,the terminal is connected to the associated CE via a serial line. The CE is called PTCE(Permanent Test Control Element). This CE contains the software necessary to carry out itsfunctions (e.g. access to target CEs, debugging of programs, message traces, etc...). The

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results are displayed on the screen for further analysis. The software located in this CEprovides access to the target CE memory as well.

Figure 215 : MPTMON architecture

DSNPTCE

LTCE

TTCE

PLTCE

ACE

MPTMONVDU OR PC

4.2 Control Elements

4.2.1 Control element configurations

As seen in the previous chapters, the A1000 S12 control is distributed among the exchangeprocessors. These processors are located in different modules, each of them performing aspecific function in the system.

The function of a particular module may be critical to the whole system operation, therefore itmust be replaced immediately after a malfunction. On the other hand, the replacement ofCEs that perform non critical functions may be delayed. Taking this fact into account, thesystem modules will work in different modes:

a. Simplex

For CEs with non critical functions. Only one module is equipped to control a cluster.

b. Active/Hot stand–by

The module function is critical to the system operation and one pair of modules must beequipped. The two modules work in parallel and provide exactly the same output. Aspecific device must at all times select one of the two outputs.

c. Active/stand–by

The module function is critical, but the pair of modules do not work in parallel. Thestand–by module collects the output information from the active one in order to updateits own data so that it is ready to take over in case of failure of the active one. Theupdating refers only to the data, since the complete set of programs are stored in itsmemory.

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d. Load sharing

The functions will be shared among several modules that form a group. Whenrequested, one of the modules in the group performs the function. This way, the failureof one of the modules simply increases the work load of the others.

e. Spare

If another CE goes off line, then a spare CE can be loaded with the correct GLS, DLSand PLS to take over from the malfunctioning CE. The take over should be defined indatabase (per CE).

f. Cross–over

In this case, two CEs are able to reach two different clusters via hardware links. EachCE is assigned to control one of the two clusters but, in case of failure of one of them,the other CE takes the control of both clusters. This CE simply increases its work load. The cluster data is updated in both CEs, but only the software functions that are in astable phase can be taken over when the control switch is produced (i.e. only calls in astable state are maintained).

4.2.2 Terminal Control Elements (TCEs)

The TCEs are CEs which control a cluster (lines, trunks, etc.). The main TCE names andfunctions are described below:

a. Analogue Subscriber Module (ASM)

The associated TCE is named JLTCE . This TCE can handle up to 128 analoguesubscribers having an average traffic flow of 0,275 E per line. These modules work inCross–over.

b. ISDN Subscriber Module (ISM)

The associated TCE is named ISMTCE. This CE can handle up to 64 basic accesses,having a total traffic flow of 35,2 E, or an average flow of 0,275 E per B channel. Thesemodules work in Cross–over. The equipped OBC is known as ISMOBC.

c. IRSU Interface Module (IRSUIM)

The associated TCE is named IRSUIMTCE and, connected to a set of IRSUs inmultidrop, handles up to 8 mixed analog/ISDN subscriber IRSUs. These TCEs work inCross–over mode. The maximum number of subscribers to be handled by a pair ofIRSUIMTCEs is 1024 analogue lines, 512 digital or a combination. The equipped OBCis known as IRSUOBC.

d. Digital Trunk Module Low (DTML)

The name of the TCEs associated with these modules depends on the kind ofsignalling to be handled. For example:

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. DCASTCE: For CAS signalling.

. DISUPTCE: For N7–ISUP (the N7 ISUP user is handled by this module,

but the signalling link is handled by the DTM

High modules).

These modules work in Simplex mode.

e. Improved Service Circuit Module (ISCM)

The associated TCE name depends on the MF signalling system to be handled and onthe supported simplified conference bridge. Two common types of modules are:

. ISVCE–A: To control 32 MFC R2 or DTMF.

. ISVCE–B: To control 16 MFC R2 or DTMF, and 6 SCB.

In case of handling 32 MF signalling inputs, the overall maximum traffic flow supportedis 22,8 E; however, if only 16 inputs are handled, the traffic flow becomes 9,5 E. These CEs work in Load sharing mode, having one CE group for each signalling type.

The equipped OBC is known as ISVOBC.

f. Digital Announcement Module (DIAM)

The associated TCE is named DIAMTCE and provides up to 58 simultaneousannouncements that are distributed through the DSN or the tone PCM link. Thesemodules work in Load sharing mode. The associated OBC is known as DIAMOBC .

g. Digital Trunk Module High (DTMH)

This module performs, among others, the analysis of the digital signalling protocols, upto four inputs in parallel (i.e. N7 MTP part, X.25, etc.) and, sometimes, the typicalfunctions of the DTM Low.The module is also called IPTM (Integrated Packet Trunk Module). The associatedTCE name depends on the protocol to be handled:

. IPTMN7 : For N7 signalling (with IPTMN7OBC).

. IPTMU : For Primary Rate Access (with IPTMUOBC).

. IPTMN : As Protocol Handler Interface –ETSI PSN access Case A or B–(with IPTMNOBC).

. IPTMX25 : To act as a X.25 DTE in the exchange connection to a EDPC (withIPTMX25OBC).

The analysis capacity of this module is 400–500 messages/s and 300–400 frames/s.These modules work in Load sharing mode.

4.2.3 System Control Elements

The System Control Elements are CEs always equipped in every exchange. These are:

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a. Peripheral and Load (P&L)

These modules cover the main functions related to the system initialisation, the CEsand OBCs downloading, backup data, etc.. They handle the rack alarms and themaster panel for alarms. The associated processor is named PLADMCE. Two PLADMCEs, working in Active/Stand by mode, are always equipped in everyexchange.

b. Clock and Tones (C&T)

It generates and distributes the master clock towards every exchange CE and Switch inthe DSN. It also generates and distributes the tones towards every TI. The processor is named CTCE.Two CTCEs, working in Active/Hot Stand by mode, are always implemented in everyexchange.

c. Monitor Module (MONI)

It provides a set of features in order to perform different management and testfunctions. The associated CE is named MONI (or PTCE). Usually, one MONI working inSimplex mode is equipped per exchange.

d. Improved Trunk Testing Module (ITTM)

It provides trunk testing facilities. The associated processor is known as ITTMTCE, andits OBC as ITTMOBC. Usually, one ITTMTCE, working in Simplex mode, is equippedper exchange.

4.2.4 Auxiliary Control Elements

The ACEs contain centralized software and data, and perform support functions for theTCEs. Actually, all the ACEs are implemented with a 80386 or a compatible processor and 8MB RAMs. The main functions performed by the ACEs are: Call Services, PBX andCharging data storage, Exchange Defense, Operation & Maintenance remote software, N7management, Data Collection and Trunk Resource Management, Intelligent Network andOSI Stack handling.

Each group of functions are stored on several ACEs named as follows:

a. Defense ACE (DFCE)

These ACEs work in Active/Stand–By mode. There is one pair per exchange. The pairperforms the following function:

– Exchange defense (failure gathering, report analysis and defense proceduretriggering)

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b. System ACE for Call Services (SCALSV)

These ACEs work in load sharing and perform the following functions related to CallHandling:

– Prefix Analysis and Task Element Definition (PATED)

– Call and Facility Control System (CFCS)

– Charging analysis (CHAN and CGC)

– Trunk request coordination (TRC).

– Auxiliary Resource Allocation (ARTA)

Figure 216 : SCALSV configuration

loadsharing

LCE

_id of TC

E

LSSG_1

LSSG_2

LSSG_3

SCALSV1 SCALSV2 SCALSV3 SCALSV4

SCALSV5 SCALSV6 SCALSV7

SCALSV8 SCALSV9 SCALSV10

c. System ACE for Subscriber Analysis (SACELSIF)

The SACELSIF handles the subscriber analysis function. It contains the static anddynamic subscriber data. The SACELSIF works in active/standby pairs. There may bea number of these pairs per exchange, depending on the number of subscribers. TheSACELSIF pair is determined by the DNET of the subscriber that has to be analysed.

Figure 217 : SACELSIF configuration

DN

ET

active standby

active standby

active standby

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d. System ACE for PABX Resource Management (SACEPBX)

The SACEBPX handles the PABX resource management. It contains the PABX data,which is managed by the PARM FMM. The ACE works in active/standby configuration.Since there could be a large number of PABXs, there may be a number of ACE pairs.The correct pair is determined by the PABX identity.

Figure 218 : SACEPBX configuration

active standby

active standby

active standby

PA

BX

_id

e. System ACE for Administration (SACEADM)

The SACEADM handles the administrative function of the exchange. Amongst others itreceives the measurements data from the LDCs. There is one SACEADM pair perexchange, working in active/standby configuration.

f. System ACE for Charging (SACECHRG)

The SACECHRG handles:

– meter count collection (MCC): the bulk counters are stored and updated in thememory of this ACE and saved on disk at fixed intervals

– automatic message accounting (AMA): the detailed billing information is kept inmemory and saved on disk at fixed intervals

– local tax layouting (LTL).

The SACECHRG works in active/standby pairs. Each pair serves a dedicated numberof lines.

g. System ACE for Local Data Collection (SACELDC)

The SACELDC handles the local data collection (LDC). This implies the collection of allcall handling events, such as a seizure, a call release and prefix analysis. With theseevents local counters are updated.

h. System ACE for Trunk Resource Allocation (SACETRA)

The SACETRA handles the trunk resource allocation (TRA) function. This ACE worksin a very special and unique configuration: if traffic measurements indicate that N ACEs

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are needed, then one extra ACE is equipped. We therefore call this an N+1configuration. The spare SACETRA is a hot–spare ACE: it already contains the correctsoftware; it only has to initialise it’s data when it has to take over from one of the otherSACETRAs.

i. System ACE for Intelligent Network (SACEIN)

These ACEs work in load sharing mode. They perform the SSP functions in the IN.

j. System ACE for OSI Stack (SACEOSI)

These ACEs work in load sharing mode. They provide the OSI Stack interface for theCEs that need to transfer data to the EDPC via X.25.

k. System ACE for CCS N7 (and OMUP) (SACEN7 and SACEN7O)

The SACEN7 handles the CCS N7 network functions. If also the Operations andMaintenance User Part (OMUP) is equipped, the ACE is called the SACEN7O. There isone pair of these ACEs (if required). The pair works in active/standby mode.

l. Spare

On the other hand, some ACEs that have no specific function assigned, are equippedin every exchange. These ACEs are named SPARE. Their main function is to take overthe functions of any other ACE in case of failure.

m. Special configurations

Depending on the size of the exchange and the type of traffic it handles, a number ofACE functions can be combined into one ACE, or can be unbundled. Some examples:

– the SCALSV can be unbundled into a specific SCALSV for lines (SCALSVL ) and aspecific SCALSV for trunks (SCALSVT );

– the IN function (SACEIN) and the OSI function (SACEOSI) can be bundled into theSINOSI;

– the defense function (DFCE) and the CCS N7 function (SACEN7O) can be bundledinto the DFN7OCE;

– the PARM function (SACEPBX) and the charging function (SACECHRG) can becombined into the SACEPBCH .

4.3 Software principles and organisation

In the previous chapters we have seen that the system software is composed of applicationprograms, called FMMs or SSMs, and of support software, such as the Operating Systemand the Data Base Management System software. These programs are classified into

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resident programs, memory resident because they are frequently run; and overlay programs,which are loaded into memory from disk when required.

On the other hand, we can find different kinds of data: the data related to the program code(data segment) and the data belonging to the actual database.

In summary, the complete system software can be said to consist of programs and data.

4.3.1 Programs and data on mass storage media

When the SW is produced, the final result is a system magnetic tape or a system opticaldisk. At system initialization, all the information (programs and data) must be transferred tothe system from this tape or optical disk. In order to organize the system SW on this massstorage devices, it will be necessary to define a set of files according to the system structure.

There is a set of files that form the so called GENERIC LOAD SEGMENT (GLS) whichcontain the resident programs (code and data segment) for a certain CE. Other files containpieces of database data that are related to a certain microprocessor and form the DATA

LOAD SEGMENT (DLS).

On the other hand, the PLS (PATCH LOAD SEGMENT) is a code file containing a set ofpatches to be loaded into a CE, together with the GLS. This set of patches is produced toimprove or correct the original software included in the GLS, once this GLS has beenproduced.

As said before, a GLS contains the set of programs that are associated to a CE. Therefore,all the CEs that have the same function will have the same set of programs, i.e., the sameGLS. For example, let us think about the JLTCEs (J–rack Line TCEs). All the line TCEs willhave the same GLS and therefore, only one JLTCE GLS will be stored on disk. The samereasoning applies to the PLS.

Regarding the DLS, the situation is different. A certain CE will only have in storage thosepieces of database data that it uses. In the previous example, one given JLTCE will have instorage the data specific to the subscriber lines that it controls (directory numbers, telephoneset types, etc.).

There is one more set of files that contain the overlay programs. These files are named

GENERIC OVERLAY SEGMENT (GOS) . Each GOS contains the code and its patches,together with the associated code data, for a specific overlay program.

4.3.2 Memory organization

Every CE memory is organized by splitting it up into several functional areas. This is done byassigning different addresses and sizes for different memory contents, i.e., by mapping thememory. The memory map is then provided to the Operating System allowing it to optimallymanage the CE memory resources.

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The resident programs (resident related FMMs, all related SSMs, required part of theOperating System and of the Data Base Management System) are contained in the GLS,together with their associated data segments. These programs are permanently loaded intoa fixed area of the CE memory assigned to them.

As said before, there is a set of patches (the CE PLS) associated with the residentprograms. These patches are also loaded into a fixed memory area.

The pieces of database data related to a CE make up the its own DLS. The DLS varies forthe different system CEs, since they all contain different data, however, the DLS size andstructure is identical for all the CEs of the same type. This data is permanently stored in afixed memory area reserved for this purpose.

Another memory area is reserved for loading the overlay programs when required. The sizeof this area is defined as a function of the overlay programs that must be concurrentlyexecuted in the CE in question.

Furthermore, there are other memory mapped areas that are reserved for differentpurposes. For example, one area will contain the message buffers, another one the userbuffers and process stack segments, a third one the TI PRAM, etc.

Figure 219 : Simplified memory layout

ROM AREA

BUFFER MESSAGE AREA

USER BUFFER AND STACK AREA

CODE SEGMENT AREA

DATA SEGMENT AREA

OVERLAY RESERVED AREA

DATABASE AREA

PATCHES AREA

4.3.3 CE logical and physical identities

The complete set of functions to be performed by the system are distributed among all theCEs. Using the TREX example seen in the previous chapter, we can see that the analoguesubscriber connections are performed by twelve JLTCEs, the call control service functionsby two SCALSVs, the defence functions by two DFN7OCEs, the MF analysis and generationby four ISVCEs, etc.

Moreover, within every functional set of CEs, each CE has a specific function: each JLTCEsupports 128 particular subscribers, one of the two DFN7OCE is active while the other one

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is in stand–by, etc. According each function is identified by a number called Logical Identity.A particular Logical Identity is related to a particular function and, therefore, associated withthe exchange CE that performs this function.

On the other hand, every system CE is connected to a particular point of the DSN, i.e., everyCE is at a permanent location defined by the coordinates W, X, Y, and Z. This set ofcoordinates is called CE Network Address or Physical Identity.

The relationships between the logical and physical identities of the CEs are defined by theconfiguration data. At system initialization, a basic configuration data set (provided for everyexchange in the system tape or optical disk) drives both P&Ls to download the CEs, andthus, assign the logical and physical identities for every CE. These relationships betweenboth identities must be stored in all CEs, and updated when necessary since they willchange throughout service life of the exchange.

Let us see two examples. First, when a SCALSV fails it can be substituted by the SPAREone. In this situation, the logical identity of the first ACE will be linked to the physical identityof the SPARE, once the latter has been loaded with the SCALSV GLS, DLS, and PLS fromdisk. Secondly, let’s take two JLTCEs connected in X–over. If one of these two JLTCEs fails,its logical identity will be assigned to its mate which will then have two logical identities : itsown plus that of the faulty JLTCE.

4.4 J–Rack family

In the A1000 S12 system exchange implementation, up to seven different rack types areused: the J–Family Rackset. Each of these rack types can contain a fixed number ofmodules with their related PBAs. However there is no relation between the rack type and thetype of modules inserted in it. A variable module means that different type of modules canbe inserted in the same position within the rack.

Each rack layout is flexible, allowing different rack contents to be defined for differentexchanges. To cope with all this, four variable modules are defined: the V01M, V02M, V03M,and V04M .

In the rack documents the PBA positions are indicated as follows:

VnnMCxx or VnnMTxx

nn = variant type (01, .., 04)xx = numbering within the rackC = CE position (MCUA,...)T = Terminal position (ALCN, DTRI, ...)

The V01M module type defines all modules composed of only one PBA (i. e. the ACEs–MCUB PBA–). The V02M module type includes all modules composed of two PBAs (i.e.the IPTM – MCUB+DTRI PBAs–). The V03M includes those modules that have up to eightcluster PBAs (i.e. the ASM –MCUA/E+ 8 ALCN PBAs–).

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On the other hand, the DIAM module is a special case, that can be only equipped intodefined locations in some of the racks. Thus, a fourth variable module type is defined, theV04M one, which covers all the two–PBA modules as well as the DIAM one.

Inside a rack, when an slot is defined to equipped a V02 module, also any V01 module maybe equipped into that slot. The following table shows some of the major module groups.

Figure 220 : Variable modules

Module Control Cluster V01 V02 V03 V04 Auxiliary Control Element (ACE) MCUB – x x xAnalogue Subscriber Module (ASM) MCUA/E ALCN xHigh Digital Trunk Module (DTM–H) MCUB DTRI x xLow Digital Trunk Module (DTM–L) DTUA/E – x x xISDN RSU Interface Module (IRIM) MCUB DTRF/H x xImprove Service Circuit Module (ISCM) MCUA/E DSPA x xISDN Subscriber Module (ISM) MCUB ISTA/B/C x

An exception to the previous grouping are the system modules: the PLADMCE, the CTCE,the DFN7OCE, the MONI, and the ITTMTCE, which are always equipped in fixed positionsin the JF00 rack.

The following table shows the different rack types in the J–Family, and the correspondingmodule type provisioning and switch PBAs included in it (Access Switch and Group Switchstages 1, 2, and 3). The full rack capacity is considered.

Figure 221 : Rack Types

Rack DSN

V01 V02 V03 V04 ACE PTCE C&T P&L TTM DEF AS GS GSType 1/2 3

JF00 4 2 6 9 1 2 2 1 2 6 32JA00 12 8 10JB00 6 8 10 10 32JH00 80 18 32JH01 20 48 22JJ00 54 18 22 32JJ01 40 10 16 64

As an example, the JF00 rack type can be taken. The following figure shows its simplifiedrack layout. Notice the fixed PBA locations for the DFN70CE?, PLADMCE, CTCE, MONI,and ITTMTCE.

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PBAs in black represent the SWITCH PBAs.

MCUB slots have to be equipped with the system ACEs (no V01M modules), and MCUXslots identifies the slot for a MCUA or MCUB PBA. MDS represents the Magnetic DiskSystem.

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Figure 222 : JF00 simplified rack layout

16 SWITCH PBAs

MCUB

V01

V02

V02

V03

control PBA

cluster

DEF

MONI

MCUB

CTCE

ITTMTCEMDS MDS

JF00

2

3

4

6

7

8

16 SWITCH PBAs

MCUB

V01

V02

V02

MCUB

MCUB

V03

control PBA

cluster

V02 DEF

MCUX

MCUB

V02

VO1

CTCE

VO1

MCUB MCUB

PLCE PLCE

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4.5 Training Exchange (TREX)

At this point, it is useful to have a look at the equipment of a real exchange and itsimplementation in different racks. This exchange will be called Training Exchange (TREX).

The exchange has to provide services in the following environment:

� 1536 analogue subscriber lines

� 512 ISDN Basic Accesses

� 2 ISDN Primary Rate Accesses

� 1 multidrop IRSU link

� 180 CAS–R2 Trunks (Route–1) to exchange A

� 60 CAS–R2 Trunks (Route–2) to exchange B

� 120 ISUP Trunks (Route–3) to exchange C

� X.25 PSN 2 Mb/s digital link (via Protocol Handler Interface)

Figure 223 : Training Exchange environment

ALCATEL1000 S12

EXCHANGE

LOCAL CONNECTIONS REMOTE CONNECTIONS

BAs

ANALOG

1

512

1

1536

PRA

IPBAX

ROUTE–1

CAS R2

180

Trunks

EXCHANGE A

EXCH. B

ROUTE–2

CAS R2

60 Trunks

1

1

2

IRSU

PCM

ROUTE–3

N7–ISUP

120 TrunksEXCHANGE C

PSN–NODE

PHI

1

1

According to the dimensioning rules, the types and the number of the different modulesrequired for the exchange are:

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� – 12 analogue line modules ( 12 modules * 128 lines/module = 1536 lines)

� 8 ISDN line modules ( 8 modules * 64 lines/module = 512 lines)

� 8 DCASTCE–R2 modules ( 8 modules * 30 trunks = 240 trunks).To handle MF signalling, 4 ISVCE modules are equipped.

� 2 DISUP plus 2 IPTMN7 modules ( 4 modules * 30 trunks/module = 120 trunks).The N7 signalling is handled by both IPTMN7.

� 1 IPTMX25 to perform the DTE functions

� 1 IPTMN to link with the PSN using Case A or B ETSI scenarios

� 2 IPTMU (one module per PRA link)

� 2 IRSUIM (two PCM links towards one multidrop)

� 2 P&L, 2 C&T (system modules)

� Requried System ACEs

� Other modules.

Figure 224 : TREX spider diagram

DSN

SPARESACEs

1

10 – SLDCTRA (2)– SACEPBCH (2)– SINOSI (2)– DFN70CE(2)– SCALSV (2)

JLTCE

12

2

DIAM MONI

1

ITTM1

2

PLADMCE

2

CTCE

IPTM X.25

IPTMN1

1

DCASTCE

DISUPTCE

IPTMN7

8

2

2

4

ISMTCE

8

IRSUIMTCE

2

IPTMU

2

ISVCE

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As we will see later on, all these modules are distributed into 10 TSUs, which are connectedto the planes using 3 Group Switches in the first stage. Therefore, three TUs and thus, onesection must be implemented.

Regarding the dimensioning rules, only six switches, in the second stage, and four planesare needed to achieve the traffic goals.

Physically, all these modules grouped as TSUs, and the DSN are located in three racks: theJF, the JB, and the JA.

Figure 225 : TREX rack contents

JF JB JA

PLANE 0PLANE 1

PLANE 2PLANE 3

3 TSUs– Analogue lines– CAS Trunks– ISUP Trunks

– Services– P&L– C&T– ACEs

4 TSUs– Analogue lines– CAS Trunks– ISDN Lines– Services– Trunk PHI– Link X.25– Link PRA– IRSU int.– iSUP Trunks

3 TSUs– ISDN Lines– Analogue LInes– CAS Trunks

The connection between the multiports for this two–stage and four–plane DSN is shownbelow:

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Figure 226 : DSN architecture

4 TSUs

2 TSUs

4 TSUs

0

1

7

8

15

01

7

8

15

9

01

7

8

15

9

01

7

8

15

9

01

7

8

15

9

0

1

7

8

15

9

0

1

7

8

15

9

01

7

8

15

0

1

7

8

15

0

1

2

0

1

2

3

4

5

13

13

13

2

2

2

2

2

2

PLANE 1

PLANE 0

STAGE 1 STAGE 2

PLANE 2

PLANE 3

The complete list of TREX CEs is given is the following table. It also includes the CENetwork Addresses, the rack type, and the subrack and slot numbers where they arelocated. The list is sorted by the Network Addresses.

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Figure 227 : TREX CEs (a)

0030 ISMTCE JB 08 13 0031 ISMTCE JB 08 33 0032 JLTCE JB 07 01 0033 JLTCE JB 07 45 0034 DCASTCE JB 03 29 0035 DCASTCE JB 03 63 003E SLDCTRA JB 03 01

NA CE RACK TYPE SUBRACK SLOT

0000 JLTCE JF 04 01 0001 JLTCE JF 04 33 0002 DIAM JF 06 31 0003 DIAM JF 06 63 0006 MONI JF 06 23 0007 ITTM JF 08 55000C PLADMCE JF 06 13000D PLADMCE JF 06 4 000E SCALSV JF 06 250010 IPTMN7 JF 03 110011 IPTMU JF 03 430012 DISUPTCE JF 07 230013 DISUPTCE JF 07 550016 SACEPBCH JF 03 310017 SINOSI JF 03 63001C CTCE JF 07 17001D CTCE JF 07 49001F SCALSV JF 07 570020 ISVCE JF 03 250021 ISVCE JF 03 570022 DCASTCE JF 03 290023 DCASTCE JF 03 610027 SPARE JF 06 25002C DEFN7OCE JF 06 21002D DEFN7OCE JF 06 53002E SINOSI JF 03 01 002F SACEPBCH JF 03 33

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Figure 228 : TREX CEs (b)

NA CE RACK TYPE SUBRACK SLOT

003F SLDCTRA JB 03 33 0100 ISMTCE JA 06 19 0101 ISMTCE JA 06 51 0102 ISMTCE JA 04 19 0103 ISMTCE JA 04 51 0110 ISMTCE JA 03 13 0111 ISMTCE JA 03 45 0112 DCASTCE JA 04 31 0113 DCASTCE JA 04 63 0200 IRSUIM JB 06 31 0201 IRSUIM JB 06 63 0202 IPTMU JB 04 31 0203 IPTMN7 JB 04 63 0210 IPTMX25 JB 08 03 0211 IPTMN JB 07 35 0212 DCASTCE JB 03 11 0213 DCASTCE JB 03 43 0220 JLTCE JB 06 19 0221 JLTCE JB 06 51 0222 JLTCE JB 04 19 0223 JLTCE JB 04 51 0224 ISVCE JB 03 25 0225 ISVCE JB 03 57 0230 JLTCE JA 08 13 0231 JLTCE JA 08 33 0232 JLTCE JA 07 01 0233 JLTCE JA 07 45

Next, the structures of the 3 TUs are shown:

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Figure 229 : TU 0 structure

7

ÏÏÏÏ

6

ÌÌÌÌÌÌ

5

ÑÑÑÑÑÑ

4

3

ÏÏÏÏÏÏ

2

ÌÌÌÌÌÌ

1

ÑÑÑÑÑÑ

0

Module CE

0 JLTCE

1 JLTCE

2 DIAMTCE

3 DIAMTCE

6 MONI

7 ITTMTCE

Module CE

0 IPTMN7

1 IPTMU

2 DISUPTCE

3 DISUPTCE

6 SACEPBCH

7 SINOSI

Module CE

0 ISVCE

1 ISVCE

2 DCASTCE

3 DCASTCE

7 SPARE

Module CE

0 ISMTCE

1 ISMTCE

2 JLTCE

3 JLTCE

4 DCASTCE

5 DCASTCE

TU 0

Module CE

12 PLADMCE

13 PLADMCE

14 SCALSV

Module CE

12 CTCE

13 CTCE

15 SCALSV

Module CE

12 DFN7OCE

13 DFN7OCE

14 SINOSI

15 SACEPBCH

Module CE

14 SLDCTRA

15 SLDCTRA

PLANES

ACCESS SWICTHES

0 1

01

2

0

52 3

JF

JF

JB

JB


5

4

1

0

Module CE

0 ISMTCE

1 ISMTCE

2 ISMTCE

3 ISMTCE

Module CE

0 ISMTCE

1 ISMTCE

2 DCASTCE

3 DCASTCE

TU 1PLANES

ACCESS SWICTHES

0 1

0 0

1

2 52 3JA

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7

ÏÏÏÏÏÏÏÏÏ

6

ÌÌÌÌÌÌÌÌÌ

5

ÑÑÑÑÑÑÑÑÑ

4

3

ÏÏÏÏÏÏÏÏÏ

2

ÌÌÌÌÌÌÌÌÌ

1

ÑÑÑÑÑÑÑÑÑ

0

Module CE

0 IPTMX25

1 IPTMN

2 DCASTCE

3 DCASTCE

Module CE

0 JLTCE

1 JLTCE

2 JLTCE

3 JLTCE

4 ISVCE

5 ISVCE

Module CE

0 JLTCE

1 JLTCE

2 JLTCE

3 JLTCE

TU 2PLANES

ACCESS SWICTHES

0 1

01

2

0

5

Module CE

0 IRSUIMTCE

1 IRSUIMTCE

2 IPTMU

3 IPTMN7

23

JB

JA

Finally, a simplified rack layout of the exchange is given on the next three figures. Only mainPBAs are shown. The Access Switch PBAs are drawn in black.

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Figure 232 : JF rack simplified layout

SWITCH SWITCH

SINOSI

DCAS

S.PBCH

ISVCES.PBCH

DCAS

SINOSI

ISVCE

IPTMN7 IPTMU

JLTCE

mcua

alcn

JLTCE

mcua

alcn

PLADMCE

mcub DFN70CE

MONI

DIAM

SCALSV PLADMCE

mcubDFN70CE

SPARE

DIAM

CTCE

mcubccla

rccb

DISUP CTCE

mcubccla

rccb

DISUP

SCALSV

ITTMTCE

mcua

MDS MDS

JF00

1 3 17 33 35 47 4915 31 63

111

2529 31

33

43 57 61 63

1

13 21 23 2531

45 53 55 63

17 23

55

55 57

2

3

4

6

7

8

002E 0010 0020 0022 0016 002F 0011 0021 0023 0017

00010000

000C 002C 0006 000E 0002 000D 002D 0027 0003

001C 0012 001D 0013 001F

0007

33

49

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Figure 233 : JB rack simplified layout

SWITCH SWITCH

SLDCTRA

DCAS

ISVCE

DCAS

JLTCE

mcua

alcn

SLDCTRA

DCAS

ISVCE

DCAS

IPTMU IPTMN7

JLTCE

mcua

alcn

JLTCE

mcua

alcn

IRSUIM

JLTCE

mcua

alcn

IRSUIM

ISMTCE

mcub

ista

ISMTCE

mcub

ista

IPTMX25

JLTCE

mcua

alcn

IPTMN

JLTCE

mcua

alcn

2

3

4

6

7

8

JB00

1 3 17 33 49

111 25 29 33 43 57 63

19 31

51

63

19 31

51

63

1 35 45

3 13 33

003E 0212 0224 0034

0222 0202

003F 0213 0225 0035

0223 0203

0220 0200 0221 0201

0032 00330211

003100300210

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Figure 234 : JA rack simplified layout

ISMTCE

mcub

ista

JLTCE

mcua

alcn

JLTCE

mcua

alcn

ISMTCE

mcub

ista

JLTCE

mcua

alcn

JLTCE

mcua

alcn

ISMTCE

mcub

ista

ISMTCE

mcub

ista

mcub

ISMTCE

mcub

ISMTCE

JA00

13 45

19 51

19 51

145

13 33

2

3

4

6

7

8

ista ista

0110 0111

0113010301120102

DCAS DCAS

31 63

0100

0203

0101

0233

02310230

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4.5.1 Rack alarm gathering

In every rack there are some events, not directly controlled by the Control Elements includedin it, which have to be reported to the maintenance software. These events are, for instance,malfunctions in the DC/DC converters, the fuses and the clock and tones distribution.

In order to gather all these events from the rack circuitry, a new PBA is provided: the RLMC(Rack aLarM version C). Two of these PBAs are equipped in every rack, and they areassociated to two Control Elements. These CE are responsible for managing the reportsgenerated in the RLMC.

This alarm board is composed of a group of alarm inputs which are connected to a memoryregister that stores the occurred events. A DPTC circuit is responsible for the protocolcommunication with the associated CE, in a similar way as used for the ALCN board of theASM.

Figure 235 : Simplified RLMC board

REGISTER

DPTC

INPUT ALARMS

RLMC

PCM Links

Taking the TREX as example, two RLMC PBAs are equipped in each of the three racks. Inthe JF00 rack, both PBAs are associated with the PLADMCEs, and in the JB00 and theJA00, the boards are associated with the line modules, as the following figure shows:

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Figure 236 : The RLMC boards in the TREX

JF00

air baffle

2

3

4

6

7

8

RLMC PLADMCE

JB00

air baffle

2

3

4

6

7

8

RLMC

ISMTCE

JA00

air baffle

2

3

4

6

7

8

RLMC JLTCE

JLTCE

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5. CALL HANDLING OVERVIEW

5.1 Possible accesses to an exchange

Figure 237 : Incoming/Outgoing accesses

DSN

ASM

ISM

IPTM

DTM

DTM

BA

PRA

CAS

Nr7

PABX

ASM

ISM

IPTM

DTM

DTM

BA

PRA

CAS

Nr7


DTMCAS

DTM

CAS

PABX

� An analogue subscriber telephone set is connected to an exchange via the a– andb–wire. In chapter 2.3.1 we saw that analogue lines are connected to A1000 S12 via anAnalogue Subscriber Module (ASM).

� An ISDN subscriber is connected via a Basic Access (BA) which is a digital access usingtwo B–channels and one D–channel. The BAs are connected to an ISDN SubscriberModule (ISM)

� An IPABX is connected via 1 or more PRAs which consist of 30 B–channels and 1D–channel. An IPTM (Integrated Packet Trunk Module) can handle a PRA when loadedwith the correct software.In general, accesses used for traffic towards PBXs can be of the following types :

– analogue line

– basic access

– PRA channel

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– Trunk channel

� Connections to other exchanges are via trunks (PCM) which can use different signallingsystems like No7, R2/CAS, R1, Nr5, ... The drawing below shows a DTM (Digital TrunkModule) as access module. From chapter 2, we know that this can be an DTUA/E forCAS, and an IPTM/DTUB or DTUA/E + IPTM/DTUB/HCCM for No7.

� Definitions:

– When both the originating access and the terminating access are subscribers, thecall is named a local call . The switching is done within the exchange.

– When the origination is a subscriber and the dialled digits result in a trunk channelselection, the call is named an outgoing call .

– When the call enters the exchange via a trunk channel and terminates towards asubscriber, it is named an incoming call .

– When the call enters via a trunk channel and leaves the exchange towards the nextexchange, it is named a transit call .

5.2 Overview of the call types

During a call setup it is possible that different accesses are combined. Figure 238 gives theoverview and can be used for all call types:

� [1] + [2] in the same exchange = Outgoing Call

Examples:– Analogue to No7 or MF/R2 trunk.– ISDN to No7 or MF/R2 trunk.

� [3] + [4] in the same exchange = Incoming Call

Examples:– No7 or MF/R2 trunk to analogue – No7 or MF/R2 trunk to ISDN.

� [1] + [4] in the same exchange = Local Call

Examples:– Analogue to analogue subscriber– Analogue to ISDN subscriber and vice versa.

� [3] + [2] in the same exchange = Transit Call

Examples:– No7 to No7 trunk

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– MF/R2 to MF/R2 trunk– No7 trunk to MF/R2 trunk or vice versa.

However in all these cases the scenarios are similar. Most of the differences are related tosignalling differences.

Figure 238 gives some call possibilities for analogue subscribers and N7 trunks.

Figure 238 : Overview Call Types

ASM IPTM

SCM

STP

ACE

IPTM

IPTM

ASM

ACE

IPTM

(No7)

No7

No7

Originating Exchange

Destination Exchange

DSN

DSN

12

34

The modules perform the following functions :

� ASM

This is the Analogue Subscriber Module

� SCM

If the subscriber is allowed to have a PBR telephone set, we need a SCM to detect theDTMF. This is of course only necessary in the originating exchange.

� IPTM

The IPTM (Integrated Packet Trunk Module) is used for two purposes:

(1) Speech connection (via a trunk channel)

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(2) Inter exchange signalling (No7)

The drawing shows two IPTMs per exchange to indicate that the speech connectionand the signalling path are independent of each other. It is possible that the No7messages are transmitted via the same IPTM as the speech connection, but they mayalso be transmitted via another link, possibly via a Signalling Transfer Point (STP).

It is also possible to use a DTUA/E + HCCM for the No7 link, or HCCM + IPTM, orDTUA + IPTM, or .... For more information see also PART I.

� ACE

This function is necessary for software support such as, call control, prefix analysis,trunk search, subscriber identification.

– The call is an example for Belgium. This means :

– Closed numbering;

– Zone with Directory Number (DN) = 7 digits, represented by D1......D7;

– Number of prefix digits = 3.

5.3 Call handling blocks

Figure 239 shows the possible accesses for CALL ORIGINATION and CALLTERMINATION which were discussed in the previous chapters. The figure will be used tobriefly explain the call flow. CFCS is drawn over the links between the different blocks,because we know from the previous chapter that CFCS is used during the call setup.

� Prefix Analysis

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Figure 239 : Prefix analysis

ISDN BA

ISDN PRA

Trunk(CAS)

PrefixAnalysis

SubscriberIdentif.

AnalogueLine

ISDN BA

ISDN PRA

Trunk(CAS)

Trunk(No7)

AnalogueLine

CALLORIGINATION

CALLTERMINATIONDEFINE CALLED DEVICE

TrunkSearch

PARM

CFCS

Trunk(No7)

This block will receive the digits coming from the Call Origination. During call setup thenecessary number of prefix digits is retrieved from database. Prefix analysis checksthese digits and can ask for more digits if necessary.The result can be LOCAL or OUTGOING.

In case the result is OUTGOING CALL , the trunk search building block is accessed.

In case the result is LOCAL , the subscriber identification building block is accessed.

This results in three cases, which are explained in the following paragraphs.

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5.3.1 Terminating or Local Call

Figure 240 : Terminating or Local Call

ISDN BA

ISDN PRA

Trunk(CAS)

PrefixAnalysis

SubscriberIdentif.

AnalogueLine

ISDN BA

ISDN PRA

Trunk(CAS)

Trunk(No7)

AnalogueLine

CALLORIGINATION

CALLTERMINATIONDEFINE CALLED DEVICE

TrunkSearch

PARM

CFCS

Trunk(No7)

� Subscriber Identification

In this case prefix analysis found that the call is LOCAL. However, from the point ofview of the exchange the call is LOCAL if the call originates in this exchange, and thecall is TERMINATING if the call origination is a trunk.

In both cases it is up to the subscriber identification to identify the call termination,which is an analogue line or a Basic Access.

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5.3.2 Transit or Outgoing Call

Figure 241 : Transit or Outgoing CallÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

ISDN BA

ISDN PRA

Trunk(CAS)

PrefixAnalysis

SubscriberIdentif.

AnalogueLine

ISDN BA

ISDN PRA

Trunk(CAS)

Trunk(No7)

AnalogueLine



TrunkSearch

PARM

CFCS

Trunk(No7)

� Trunk Search

In this case prefix analysis found that the call is OUTGOING. However from the point ofview of the exchange the call is OUTGOING if the call originates in this exchange, andthe call is a TRANSIT if the call origination is a trunk.

In both cases it is up to the Trunk Search mechanism to define a module to switch tothe next exchange (=Trunk module No7 or CAS)

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5.3.3 Hunting to lines/trunks

Figure 242 : Hunting to lines/trunksÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

ISDN BA

ISDN PRA

Trunk(CAS)

PrefixAnalysis

SubscriberIdentif.

AnalogueLine

ISDN BA

ISDN PRA

Trunk(CAS)

Trunk(No7)

AnalogueLine



TrunkSearch

PARM

CFCS

Trunk(No7)

� Private Access Resource Manager (PARM)

In this case prefix analysis found that the call is LOCAL. As in chapter 5.3.1 the call canbe local or terminating. Therefore the subscriber identification is accessed. The resultof subscriber identification is a PABX identity which is passed towards PARM.

PARM executes line hunting in case the destination is BA or an analogue line. In thecase of an (I)PABX connected to a PRA or CAS trunks, trunk hunting is executed tofind an outgoing trunk or PRA. This function is similar to the trunk search the previouschapter.

5.4 Overview of the call phases

5.4.1 Originating exchange

Figure 243 is the flowchart for the originating (local or outgoing) exchange.

The call origination is an analogue subscriber using a PBR telephone set.

After prefix analysis the call is LOCAL or OUTGOING. The ”end of dialling” and the ”releaseof the receiver” are still common, but the subsequent actions are different for the local and

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the outgoing call. However many actions are similar and are therefore printed on the samehorizontal level.

The flowchart is read from top to bottom. Every time the flow is interrupted, this means thatthe exchange is waiting for an external action, which is a subscriber action or a No7message.

With this flowchart it is possible to handle two call types: the left branch is the LOCAL CALLand the right branch is the OUTGOING CALL .

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Figure 243 : Originating Exchange

RELEASE RECEIVER

SUBSCRIBER

SEIZURE

PREPARE & SEND DIAL TONE

DETECTION OF PREFIX DIGITS

PREFIX ANALYSIS

LOCAL OUTGOING

END OF DIALLING

OUTGOING TK SELECTION

OUTGOING TK SEIZURE

PASS TO STABLE PHASE

ANSWER

TERMINATING SEIZURE


ANSWER

IAM

ACM

ANC

C O N V E R S A T I O N

FORWARD RELEASE FORWARD RELEASE

CLF

CLEARRLG

SUBSC. IDENTIFICATION

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5.4.2 Incoming exchange

In the incoming exchange the origination is a trunk (see figure 244). In this example a No7trunk is used, so the incoming seizure is a Nr7 IAM (Initial Address Message) coming fromanother exchange.

After the prefix analysis there are again two possibilities:

� The call is local and terminates in this exchange (an analogue subscriber in our example)This is an INCOMING CALL .

� The call is outgoing and will leave the exchange via a trunk (No7 trunk in this example).This is called a TRANSIT CALL .

Figure 244 : Incoming Exchange

TRUNK

SEIZURE

PREFIX ANALYSIS

LOCAL OUTGOING

OUTGOING TK SEIZURE



ANSWER

TERMINATING SEIZURE


ANSWER

IAM

ACM

ANC



CLF

CLEAR

RLG


ACM

IAM

ACM

ANC ANC

CLF CLF

RLGRLG

These two flowcharts will be used in the description of the different call types.

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5.5 Generic call scenario

The previous chapter discussed the various possible accesses. Depending upon thecombination, a call can be local, outgoing, incoming or transit. This chapter outlines a common scenario which is independent of the access and can beused for all types of call. The discussion of the scenarios includes the prefix analysis, subscriber identification andtrunk search items. In the paragraphs following the scenarios, these items are explained ingreater detail because of their importance. As shown in figure 245, these software blocksare called Call Services .

5.5.1 Call Setup

This scenario shows the interface between call services, CFCS, signalling and devicehandling.

� 1 : SETUP or Origination message

After reception of the off–hook event for an analogue subscriber or the SETUPmessage for an ISDN subscriber or the IAM for No7 trunks or the Seizure on a CAStrunk, the call is activated in Signalling.

Signalling stores a reference for this call, which is used during the call handling to

identify the call. In other words, a transaction is created for each call request froma user (the information is stored in a Transaction Control Block which is a uniquenumber). A transaction is also created whenever a situation occurs where extraresources are needed that cannot be catered for within the existing transaction.

A transaction can contain references to three paths :

– a main path (=speech path in stable phase)– a temporary path (=intermediate for 3 party service, ...)– a system path (=towards SCM,...)

If these three paths are not sufficient, another transaction is created.

� 2 : SELECT CHANNEL

The device handler (DH) selects a free cluster path for the duration of this call. This is achannel on the cluster side of the terminal interface.

The seized device is also put ’available busy’ by the DH.

The message also contains ’join information’. Later in the setup phase a path isestablished between the SCM and the analogue subscriber for DTMF. So, for an

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analogue subscriber this join information means a connection between the cluster pathand the SCM–path. This is not true for an ISDN subscriber. For the latter the joininformation means a connection between the cluster path and the path leading to thecall termination, when it is defined later.

� 3 : CHANNEL INFORMATION

This message also indicates a positive acknowledgement that the cluster channel isavailable.

At this point CFCS can be activated. However, in parallel with the CFCS activation, it ispossible to request an auxiliary device (e.g: SCM receiver, if needed for DTMF or MF). Thismeans that [4] and [4’] are transmitted in parallel.

� 4’ : SELECT AUXILIARY DEVICE

The device can be a DTMF receiver (for an analogue subscriber) or an MFsender/receiver (for CAS trunks). The selection of a SCM is executed by a separateFMM (ARTA : Auxiliary Resource TCE Allocator). The selection mechanism isexplained in chapter 6. The selected SCM establishes a path towards the originationmodule where it is joined to the cluster path. Via this path the SCM receives the DTMFtones coming from the subscriber or the MF signalling between the two exchanges.In the case of a DTMF receiver, dial tone is already transmitted towards the subscriberand the SCM is ready to detect DTMF tones.

� 4 : ACTIVATE CFCS

CFCS is activated for this call using the call reference (identity) mentioned earlier.

� 5 : ACKNOWLEDGEMENT

Acknowledgement towards Signalling of the successful activation of CFCS.

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Figure 245 : Call Setup

DeviceHandler

Signalling

CFCS

SubscriberIdentification/PARM

Prefix Analysis

Trunk Search

Signalling

DeviceHandler

1

17,2 3

13,9,4 5,8,12,16,23

14,6 7,15

4’

10 11 14’ 15’

18

19

20

21

22 24

CALL SERVICES


� 6 : GET CLASSES

The data profile of the calling subscriber is retrieved from Subscriber Identification.Also the dial tone type and the required amount of prefix digits can be indicated heredepending on the facilities of the subscriber.

� 7 : CLASSES RESULT

The results are sent back towards signalling. Based upon the facilities the number ofdigits required for prefix analysis can change. This is also retrieved here.

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� 8 : DIGIT REQUEST

Signalling receives the number of digits (=prefix digits) needed and passes them to theSCM.

� 9 : DIGITS

Signalling sends the digits towards CFCS. For analogue subscribers, e.g., the digitswere received from the SCM.Signalling sends all the digits it has received up to then, but the minimum is the numberof digits required. For ISDN subscriber and for No7 all the digits were received”en–block” (if applicable).

� 10 : PREFIX ANALYSIS

The digits are transmitted to ”Prefix Analysis” to be analysed. More details on the prefixanalysis will be given later in this chapter.

� 11 : PREFIX ANALYSIS RESULT

As explained before, the result can be LOCAL or OUTGOING.

Prefix Analysis also detects the remaining number of digits required.

� 12 : DIGIT REQUEST

Request to signalling for the remaining number of digits.

Again for an analogue subscriber, the request is further transmitted towards the SCM.The latter will send the digits to signalling after reception. The SCM is then releasedbecause it is no longer needed.

� 13 : DIGITS

Signalling sends the remaining digits towards CFCS. Remember that there were twopossibilities : LOCAL or OUTGOING.

LOCAL : Subscriber Identification is accessed (see [14] and [15])

OUTGOING : Trunk Search is accessed (see [14’] and [15’]).

� 14 : SUBSCRIBER IDENTIFICATION

Here, the prefix analysis result and the remaining digits are used to fetch the profile ofthe called party and define the call termination module.

� 15 : RESULT

The result is passed to CFCS

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� 14’ : TRUNK SEARCH

The prefix analysis result and some other information is sent to trunk search.

� 15’ : RESULT

Trunk search has retrieved the identity of the terminating trunk module (for more detailson the trunk search mechanism, see later in this chapter).

� 16 : INFORM SIGNALLING

Signalling is informed about the termination identity.

After analysis is complete, determination of the destination of the call, and selection ofthe terminating resource (see above), a seizure is sent.

� 17 : JOIN INFO

This message is sent only for analogue subscribers, because the previously mentionedjoin information for analogue subscribers indicated a path coming from the SCM. Nowan indication is given that the main path, coming from the termination device is beingestablished.

� 18 : TERMINATING SEIZURE

This message is sent from signalling A to signalling B. In the termination module areference is created for this call.

� 19 : SELECT CHANNEL

On the termination side, signalling requests a channel to the device handler. Thismeans a cluster path and a network path, and the join information.

The ringing current and tone are started (if requested).

� 20 : SETUP SPATA PATH

The result of this message between the device handlers is the creation of a UCP (UserControlled Path). The device handler on the A side will join this path towards the clusterpath.

� 21 : CHANNEL INFORMATION

This message is also a positive acknowledgement indicating that the connections havebeen allocated.

� 22 : ACKNOWLEDGE

This message is the acknowledgement towards CFCS, because it is the latter whichhas started the terminating seizure with message [16]. It is also an indication that thealerting phase has started.

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Depending on the signalling system, this message can be split into two messages. E.g: for ISDN signalling, message 22 indicates an acknowledge and an indication towait for alerting. The signalling scenario is as follows. The called terminal is activatedwith a Q931 SETUP message. One or more terminals will send a CALL PROCEED andan ALERTING message backwards. When this alerting message from the terminatingside is received, a second message is transmitted towards CFCS.

At this moment CFCS activates charging. Charging is not further explained herebecause it is handled in PART IV.

� 23 + 24 : PASS TO STABLE PHASE

CFCS sends the stable call data to signalling A and signalling B and terminates. Theanswer and release is handled by the signalling (protocol) planes.

Customer dependent a ”wait for answer” timer is running in signalling B.

5.5.2 Answer

When the called subscriber answers, an event is received. Depending on the terminationdevice, the event can enter via the ASM hardware reporting mechanism,or via a Q931message, ...

See figure 246:

� 1 : ANSWER

The answer event enters the signalling (protocol) plane. Customer dependent, the ”waitfor answer” timer is cancelled.

� 2 : JOIN

Signalling dependent, the ringing tone and/or ringing current are removed. The clusterpath is joined to the network path.

� 3 : PASS EVENT

The answer message is passed to signalling A because signalling A will start thetaxation.

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Figure 246 : Answer

DeviceHandler

Signalling Signalling

DeviceHandler

13

2


5.5.3 Release (Local Call only)

The following scenario describes an autonomous release of the calling subscriber. Like theprevious scenarios, this scenario is access type independent.

See figure 247 :

� 1 : RELEASE

The on–hook condition enters the signalling (protocol) plane. Signalling will informcharging to stop the taxation for this call.

� 2 : INFORM DEVICE HANDLER

The DH will release the network path and the cluster path and put the line or trunkavailable free (for a new call).

� 3 : INFORM B–SIDE

Signalling B is informed about the forward release.

� 4 : ACKNOWLEDGEMENT

This is the acknowledgement for the release trigger. On receiving this message theoriginating signalling knows that the release event was received.

� 5 : INFORM DEVICE HANDLER–B

The release event is passed to the DH. The B–side is put in parking. The cluster path isdeallocated.

� 6 : ON–HOOK B–SIDE

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� 7 : RELEASE

The B–subscriber is put available free.

Figure 247 : Release

DeviceHandler

Signalling Signalling

DeviceHandler

64

5,7


13

2

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6. CALL HANDLING EXAMPLES

In this chapter many figures use numbers to indicate a sequence. In the text you can find areference to these numbers. This is done by repeating the number in the text betweensquare brackets, [number].

6.1 Local call with analogue subscribers

Figure 248 summarises the hardware which is used during the local call.

Figure 248 : Local Call

ASM

SCM

ACE

ASMDSN

1 4

Figure 249 sketches the major steps in the treatment of a local call. Every block in the figurecorresponds with a chapter.

To work out a complete example, we will have to make a number of assumptions during thecall. Some of these assumptions are listed here:

� closed numbering

� seven digit number for the subscribers

� neither the A–party, nor the B–party have any facilities active

� the number of prefix digits is three.

In the figures that indicate a sequence of actions in the software:

� a full line represents a S12 message;

� a dotted line (with indented text) represents a procedure call.

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Figure 249 : Local call overview

A–party B–partyA1000 S12

activate call control

receive prefix digitsdial digits

receive remaining digits

seize B–party

pass to stable state

hook on

hook off

stop charging

request DID

hook off

conversation

hook on

conversation

ringing currentringing tone

seize A–party

send dial tone to A–party

perform A–party analysis

perform B–party analysis

release receiver

release B–party

dial tone

release A–party

start scanning for digits

start ringing phase

perform prefix analysis

detect ring trip

prepare charging

activate charging

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6.1.1 Seize A–party

a. Actions in the hardware and operating system

Figure 250 : Hook off

ALCN 7

ALCN 0

A

B

0

15

.

.

.

..

..

LOGIC

To cross–over

PRAM

OS

DH

SIG

MCUA

DSN

12 3

4

5

[ 1 ]When the subscriber lifts the handset, the loop resistance is low and the currentthrough the subscriber’s line increases.

[ 2 ]This increase in current is detected by the hardware of the subscriber line. Thisdetection is translated into the setting of a bit. The digital logic of the subscriber sendsthis information towards the common logic of the PBA.

[ 3 ]This common logic is the communication link towards the control element processor.The processor can send commands to the logic (via CH16 = drive) and the logic cansend the results back in CH16 (=scan). If there is an event in the hardware (hook–off,hook–on, HW fault, ...) then the logic sends a CH0 alarm towards the processor.In our case (hook–off) the logic sends a CH0 alarm towards the terminal interfacePRAM.

[ 4 ]The CH0 alarm is received and detected by the OS which periodically scans the PacketRAM with a clocked procedure. Then a command is sent to the logic to ”ask” what hashappened in the hardware. The result is again received in the PRAM via CH16 and isread by the OS.

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The received information explains what happened (subscriber hook–off) and gives thesubscriber’s identity.

It consists of two words: one word indicates hook–off and the second word is the

identity. The latter is called the PTN = Physical Terminal Number .

All this information is passed to the LCRC DH SSM as follows. The OS places theinformation in a queue which belongs to the LCRC DH SSM. The latter reads thisqueue periodically (clocked procedure) and detects the creation of a new entry.

[ 5 ]The LCRC DH SSM then sends the first A1000 S12 message towards the signallingsubsystem (ASSS_TSIG). Since the message indicates the start of a new call, it iscalled the origination message .

At this point the software is activated. The scenario is summarised in figure 251. Thisfigure starts with step 5 out of the previous figure, where the LCRC DH SSM sends thefirst message of the call to ASSS_TSIG.

b. Actions in the software

Figure 251 : Seize A–party

ASSS_TSIG

SMD FMM

LCRC DH SSM

ASM (orig)

LCHG

1

23

4

5

A

Note: Because of the cross–over connections, this hook off event is also received in the cross–overmodule. However, in a normal situation the software detects that the subscriber is handled by its own

module. This is detected after the PTN to TN translation. In this case the message toASSS_TSIG is only sent in the own module.In a cross–over situation the active module takes care of all the subscribers.

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When a subscriber hooks off, the software has to mark the subscriber as busy.Furthermore, since there are only a limited number of cluster paths, one has to beallocated to the newcall.

TN = 1...128 EVEN MODULE SUBSCRIBERS

TN = 129...256 ODD MODULE SUBSCRIBERS.

[ 1 ]originationWhen ASSS_TSIG receives the origination message, it allocates a transactioncontrol block (TACB) for this call, further on labeled as ASSS_TSIG_A. During callset–up, this reference is passed from one software block to the other in the messages.So this reference identifies this call.

[ 2 ]ASSS_TSIG_A calls an interface procedure within the LCRC DH SSM to removethe terminal from origination scanning list.

Next ASSS_TSIG_A checks whether the subscriber has priority during overload. Thispriority is only important if the CE has an overload condition. The priority level is part ofthe Class Of Line (COL) data. This data is stored in a relation. There is one tuple persubscriber in the relation. The key to the relation is the TN.

[ 3 ]select channelThe actions of the SMD FMM are combined in figure 252.

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Figure 252 : Actions of the SMD FMM

POWER ON

GET COL

INITIALISATION ACTIONS

STATE FREE

MSG_WAIT

STATE:FREE STATE:BUSY

SELECTCHAN

GET CLUSTER PATH

STATE BUSY

CHANINFO

.

.

.

.

.

.

.

.

.

[ 4 ]SMD FMM calls an interface procedure to request a cluster path. Some of thesub–actions include:

– power on the the ESLIC and DSP chips on the ALCN board:To limit power dissipation in the module, the speech path only receives power whenit is needed. This is when the subscriber’s line becomes busy. The LCRC DH SSMtherefore sends a packet over channel 16 to the ALCN logic.

– allocate a cluster path (see figure 253):The allocation of a cluster path is done via an OS primitive. This primitive allocates afree Rx / Tx channel pair. Then OS sends a packet to the ALCN logic to indicate that

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subscriber X is connected to Rx/Tx channel pair Y. In this way the hardware knowsin which channel the samples are going to be transmitted and received.

Figure 253 : Cluster path allocation

ALCN 0

A

B

0

15

.

.

.

LOGIC

OS

DH

SIG

MCUA

DSN

1

3

2

4

Cluster Channel pair

e.g: CH 7

RT

RT

RT

RT

SMD FMM changes the state of the subscriber from available_free to available_busy.

Also SMD FMM checks some COL data. The data needed by the device handler aretransmission parameters:

– the receive and the transmit gain;

– the settings of the hybrid on the ALCN board.

[ 5 ]channel informationThe SMD FMM sends the result to ASSS_TSIG_A. This message includes the channelidentity and the COL information.

ASSS_TSIG_A checks some additional COL data:

– the type of set: this can be dial pulse set (also called rotary set), push button set (orDTMF set), or combined set. Let us assume that the subscriber has a combined set.In other words: the software doesn’t know whether a dial pulse set or a push buttonset will be used. In this case both types of scanning have to be triggered. As soonas the first digit is detected, the redundant scanning type can be switched off.

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– the priority during catastrophic condition: an exchange can be put in a catastrophiccondition, for example if there is an earthquake, to avoid originating traffic from anexchange;

– the presence of a hardware key is checked. A hardware key can be used to switchon or off a particular Outgoing Call Barring (OCB) level.

Also some Originating Line Class Of Service (OLCOS) data is checked. This data isstored in a relation. The most important information is the dial tone type.

A subscriber who hasn’t activated any facility, may receive normal dial tone, whereas asubscriber who has activated a Call Forwarding Unconditional (CFU) facility, mayreceive a special dial tone.

Note: The OLCOS relation mentioned only contains part of the COS data. This data is the absoluteminimum COS data that is necessary to start the call. It contains the dial tone type to send the dialtone as quickly as possible. The more advanced COS data is stored at LSIF level. Refer to chapter3.4.9.

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6.1.2 Start scanning for digits / Send dial tone to A–party

Figure 254 : Start scanning for digits and send dial tone to A–party

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM SC DH SSM

SC DH FMM

RSIG

SCALSV

ASM (ori g) SCM

CGCCHAN

LCHG

1

2 3

4

5

6

7

8

9

TRC

10

A

A

Signalling starts dial pulse scanning, finds a DTMF receiver and starts DTMFscanning.

Note: Time–out handling:During the register phase, several time–outs are used:– wait–for–first–digit time–out;– overall–dialling time–out;– inter–digit time–out.These time–outs are started in the signalling software block. Depending on the dialling type, thetime–outs are running in different CEs. The table below gives an overview.

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PB set only dial pulse set only combined set

overall–dialling time–out ASSS_ASIG_A ASSS ASIG_A ASSS ASIG_A

wait–for–first–digit time–out RSIG ASSS TSIG_A ASSS TSIG_A

inter–digit time–out RSIG ASSS TSIG_A ASSS TSIG_A orRSIG

dial tone SCM ASM SCM

[ 1 ]ASSS_TSIG_A calls an interface procedure within the LCRC DH FMM to start dialpulse scanning.

Because we assumed that the dial type is combined, we are not sure at this moment ifour subscriber is using a PBR set or a dial pulse set.

In case of dial pulse scanning the digit value is determined by the number of pulsescoming in. The pulses are created by changing the loop status from high to low andvice versa.This generates events in the subscriber line hardware in the same way as was the casefor lifting the handset. These events are reported to the LCRC DH SSM. The SSMchecks the ”making” and the ”breaking” times to verify whether they are within the limit.If the ”inter–digit” time is exceeded, then the number of pulses gives the digit value. Infigure 255 the detected digit is two.

Figure 255 : Dial pulse scanning

digit detected

inter–digittime–out

OPEN LOOP

CLOSED LOOP

66 ms

33 ms

[ 2 ]loadsharing intra signallingASSS_TSIG_A now has to link with ASSS_ASIG. ASSS_ASIG is stored in the SCALSVs. Toobtain an equal distribution of originating traffic over the SCALSVs, the message to triggerASSS_ASIG is sent in loadsharing.

The message contains the information that ASSS_TSIG_A has collected so far:

� the COL data

– dial set type;

– priority level during overload;

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– priority level during catastrophic condition;

– presence of a hardware key.

� the OLCOS data: primarily the dial tone type.

To check whether the linking was successful, ASSS_TSIG_A starts a time–out for theacknowledgement from ASSS_ASIG.

The first action of ASSS_ASIG is to allocate a TACB of it’s own, further on labeled asASSS_ASIG_A. The information received from ASSS_TSIG_A is then copied into the TACB.

[ 3 ]intra signallingASSS_ASIG_A sends an acknowledgement to ASSS_TSIG_A. The latter then stops thetime out.

[ 4 ]activate CFCSThe actions that are performed by CFCS and the subsequent steps are explained in the nextchapter.

[ 5 ]select deviceTo detect DTMF digits, a DTMF receiver has to be allocated in a SCM. This allocation isperformed in two steps:

1. a SCM has to be found that first of all has receivers of the correct type and that is available maintenance–wise;

2. the chosen SCM has to be contacted, to check whether it still has a free receiver.

To find an available SCM with the correct device type, a message is sent to the AuxiliaryResources TCE Allocator (ARTA) FMM. ARTA uses a procedural relation to find a SCM.Please refer to chapter 3.4.7 for more information on how the procedural relation works.

In the meantime a time–out is running in ASSS_ASIG_A. Three possibilities exist:

– The SCM selects a free receiver and replies to ASSS_ASIG_A via SMD FMM;

– The SCM replies with a message to indicate that no receiver is available. In thiscase ASSS_ASIG_A starts a new time–out and sends a new request to ARTA, untilmaximum number of retries is reached;

– The time–out in signalling expires. ASSS_ASIG_A sends a retry to ARTA and thelatter puts the SCM unavailable for 30 s.

Note: Queuing is also possible but is not further discussed here.

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[ 6 ]select deviceNow, ARTA sends a message to the selected SCM to continue the search for a free DTMFreceiver within the SCM. Because of the distribution of the traffic (via this cyclic searchmechanism) the possibility of finding an SCM with a free DTMF receiver is very high.

The SC DH FMM selects a free receiver and changes it’s state to available busy.

[ 7 ]seized MF registerThe SC DH FMM sets up UCP to the ASM. It is a duplex path that is held until one of theDHs (SMD FMM or SC DH FMM) asks to disconnect it. This path will be used in thedirection from SCM to subscriber to send dial tone, and in the direction from subscriber toSCM to send the DTMF digits, if at least the subscriber has a push button set. To set up theUCP the following steps are performed:

1. the DH asks a SPATA channel via an OS primitive. The NA of the ASM (destinationCE) is given as an input parameter. The identity of the allocated path is returned as anoutput parameter, so that it can be used by the process to send the message.

2. when control is returned to the SC DH FMM, the BASIC message can be sent VIAthat UCP. (get a message buffer, fill in the message buffer and send the message )

3. OS finds out that the message is sent via a UCP, so it starts a 3 packet sequence(refer to figure 256):

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Figure 256 : Setup of a UCP

1

3

2

4

RT

RT

RT

RT

ÉÉ

SCM

DSNÉÉ

1 2

3 4

RT

RT

RT

RT

ASM

aa

a

ÉÉÉÉ

ÉÉÉÉ

12

34

RT

RT

RT

RT

SCM

DSN

1 2

3 4

RT

RT

RT

RT

ASM

b

bb

ÉÉÉÉ

ÉÉÉÉ

12

34

RT

RT

RT

RT

SCM

DSN

1 2

3 4

RT

RT

RT

RT

ASM

cc

c

[ a ]Contains information to set up and hold a simplex path through the DSN from theSCM towards the ASM (selects and EOP hold). The OS in the ASM is informed toestablish a return path.

[ b ]Contains information to set up and hold a simplex path through the DSN from theASM towards the SCM (selects and EOP hold). The OS in the SCM is informed tosend the actual message via the existing path towards the SMD FMM.

[ c ]This packet does not contain select words because the path already exists. It isthe only packet which contains data (message data) to be delivered to the SMDFMM.

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When the BASIC VIA message is received in the SMD FMM, it will connect the UCPpath to the cluster path pair. This is done by calling an OS primitive which executes thejoin. The join is a duplex cut–through connection. For the result see figure 257.

Figure 257 : Join the A–party

1 2

3 4

R

T

R

T

R

T

R

T

ASM

DSN

Cluster channels

[ 8 ]start receivingThe dial tone type was retrieved from OLCOS and the dial tone should be connected assoon as possible. Also the receiver is connected to the UCP:

[ 9 ]start scanningRSIG triggers a procedure in SC DH SSM to start scanning for DTMF digits.

To connect the receiver, the Rx channel of the UCP is PUT TO RAM, so the samples arereceived in the PRAM. Then a FETCH is created to connect the PRAM location towards thechannel of the receiver.

The dial tone is available in one of the channels of the tone port. At initialisation the tonechannels are PUT TO RAM to adjacent PRAM locations. Therefore, to send the dial tone tothe subscriber, it is sufficient to FETCH from the correct PRAM location towards the UCP Txchannel. For the result see figure 258.

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Figure 258 : Connect receiver and send dial tone

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T

R

T

R

T

R

T

SCM

DSN

R

5

Receiver

DT

[ 10 ]seized registerThe ASSS_TSIG_A is informed about the successful DTMF receiver selection. NowASSS_TSIG_A can cancel the time–out which has been running since the selection startedvia ARTA.

Figure 259 gives an overview of the connections made so far in the hardware.

Figure 259 : Subscriber connections

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RT

RT

RT

RT

SCM

DSN

1 2

3 4

RT

RT

RT

RT

ASM

DT

ÉÉÉ

Receivers

R

At this moment the subscriber receives dial tone and the exchange is waiting for the digitscoming from the subscriber. The overall dialling time–out and wait–for–first–digit time–outare running. To continue the call, let us assume that the subscriber has a push button set.

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6.1.3 Activate call control / Perform A–party analysis

Figure 260 : Activate call control and perform A–party analysis

CFCS

ASSS_ASIGARTA

PATED

LSIF

SCALSV

SACELSIFCGCCHAN

2

3

TRC

1

A

An application process is created to control the call and the A–party’s profile isretrieved.

[ 1 ]call control to signallingThis message is merely an acknowledgement to ASSS_ASIG_A.

[ 2 ]data requestCFCS requests the A–party’s profile. Remember that the DNET of the A–party is used tofind the correct SACELSIF.

The profile contains:

– the Originating Line Class Of Service (OLCOS) data. One of the most importantparameters at this moment is the amount of prefix digits. This represents theminimum amount of digits that have to be collected before CFCS submits them toPATED. Let us assume that the number of prefix digits is set to three.

Note: In chapter 6.1.1 ASSS_TSIG already collected the basic OLCOS data from a relation in theTCE. Here the more advanced OLCOS data is retrieved from a number of relations.

– the facility data.

[ 3 ]data resultLSIF returns the results from analysis. Let us assume that the subscriber does not have anyparticular facility active.

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6.1.4 Receive prefix digits

Figure 261 : Receive prefix digits

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM SC DH SSM

SC DH FMM

RSIG

SCALSV

ASM (orig) SCM

CGCCHAN

LCHG

1

2

3

5

67

8

4,10,13 9,11,12,14,15

16

17

TRC

A

A

When the first digit is received the dial tone is removed and the redundant scanningtype is stopped. The first three digits are sent to callcontrol.

[ 1 ]call control to signallingCFCS passes the A–party profile to ASSS_ASIG_A. The message also contains a digitrequest. The number of prefix digits was found in chapter 6.1.3. We assumed that threedigits are requested.

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[ 2 ]digit requestASSS_ASIG_A forwards the digit request to SC DH FMM.

[ 3 ]intra signallingASSS_ASIG_A forwards the digit request to ASSS_TSIG_A.

ASSS_TSIG_A starts the wait_for_first_digit time–out.

[ 4 ]signalThe digit detection principle was explained in the chapter about the SCM. The first digitis detected by the hardware and delivered to the SC DH FMM. The digit is passed tothe RSIG.

RSIG analyses the received DTMF code. Digits with code 0..9 and ’*’ or ’#’ areaccepted. Other codes are considered as a bad digit. The digits are stored in a localdigit buffer. They are collected there until all three prefix digits have been received.

[ 5 ]first PBR digitBecause the subscriber is using a PBR set, the ASM has to be informed to stop thetime–outs and to stop the dial pulse scanning. SC DH SSM therefore reports the event toSMD FMM.

[ 6 ]disconnect toneRSIG reports the event to SC DH FMM to disconnect dial tone.

[ 7 ]eventSMD FMM reports the event to ASSS_TSIG_A. ASSS_TSIG_A cancels thewait–for–first–digit time out and the overall–dialling time–out.

The overall time–out in the SCM, however, is still running.

[ 8 ]switch off dial pulse scanningASSS_TSIG_A stops the dial pulse scanning and puts the terminal in the busy scanlist.

[ 9 ]start time–outRSIG starts an interdigit time–out.

[ 10 ] [ 13 ]signalThe next digits are detected. The actions are similar to those executed after the reception ofthe first digit.

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– cancel the interdigit time–out [ 11 ] [ 14 ];

– start a new one [ 12 ] [ 15 ];

– check the MF code for a bad digit;

– increment the number of received digits and store the digit in the buffer;

– check if the required number of digits have been received (e.g: 3).

[ 16 ]address in bunchThe first three digits are sent in bunch to ASSS_ASIG_A.

[ 17 ]signalling to call controlThe first three digits are sent in bunch to CFCS.

6.1.5 Perform prefix analysis

Figure 262 : Perform prefix analysis

CFCS

ASSS_ASIG ARTA

PATEDSCALSV

CGCCHAN

1 2

TRC

A

The first three digits that were dialled, are analysed.

[ 1 ]call control to PATEDCFCS sends the first three digits to PATED.

For our example, the message to PATED contains the following information:

� digits D1, D2 and D3 received from the subscriber.

� Type of Call (TOC), retrieved from the COS data, where it is called Calling Party Category(CPC). E.g: Normal call.

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� Numbering Plan Indicator (NPI). For originating analogue subscribers CFCS fills in E164.

� Nature of Address (NATADDR) . For our analogue subscriber it is set to ”unknown”.

� source code, which consists of:

– an indication of the source code type: here it is set to subscriber;

– a value that depends on the type. For subscribers the value is the subscriber group.

� the time of day (TOD) is retrieved from the tone port (CH1 and CH2).

Figure 263 : Input for PATED

CategoryAnalysis

Digit preparation

Digit Analysis

Received digits

Type of call

Origin

OriginAnalysis

TimeAnalysis


CPX

CAUSE

Request more digits

&

Time

ÉÉÉÉÉÉÉÉÉÉ

Tasks


D1,D2,D3

CPC (OLCOS)

(Normal Call)

NPI (E164)NATADDR (unknown)SOURCECODE Type (Subscriber) Subgrp (OLCOS)

TOD

–LOCAL–DNET–tasks ...

[ 2 ]PATED to call controlThe results of the analysis are sent back to CFCS.

The result from PATED is: Request for more digits. This is passed to CFCS which sends therequest to ASSS_TSIG_A. From there the SCM is requested for one more digit and uponreceipt the RSIG transmits it to ASSS_TSIG_A and further to CFCS. This intermediatescenario is not shown in the figures because the principle remains the same.

CFCS accesses PATED for a second time. Now four digits are presented to PATED.

PATED now finds that the call is LOCAL . In that case also a DNET is retrieved fromdatabase and all this is sent to CFCS.

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PATED also delivers some tasks :

– destination allowance check: according to the originating and destinationrestrictions, it is checked whether the destination may be accessed or not;

– start selection point: indicates the number of digits which should be received beforetrunk selection starts (not for our local call);

– charging information (=input for charging);

– priority check: if the call has priority or not;

– numbering type check: indicates open or closed numbering. For closed numberingthe number of digits of the DN is given. For open numbering a minimum andmaximum is given. Let us assume closed numbering with seven digits.

6.1.6 Receive remaining digits / Release receiver

Figure 264 : Receive remaining digits and release receiver

CFCS

ARTA

PATED

SC DH SSM

SC DH FMM

RSIG

SCALSVCGCCHAN

SCM

1

2

3

4

78

9

5,6 repeated

TRC

ASSS_ASIG

A

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The remaining digits are requested by call control. Signalling supplies them.

[ 1 ]digit requestSince we assumed closed numbering with seven digits, and we have already received fourdigits, CFCS requests three more digits. In addition CFCS indicates that this will be the lastrequest. This makes an autonomous release of the receiver possible (see later).

In case of open numbering, the SCM will pass every received digit to the ASM. This willcontinue until the called DN is complete. In other words, when the called device is defined.Only then will CFCS trigger the release of the SCM.

[ 2 ]digit requestASSS_ASIG_A requests three more digits.

[ 3 ]digit requestSC DH FMM indicates the next amount of digits to RSIG.

[ 4 ]signalThe next digit is detected.

[ 5 ]stop time–outRSIG stops the running inter–digit time–out.

[ 6 ]start time–outRSIG starts a new inter–digit time–out.

Actions 4,5 and 6 are repeated for every next digit, except for the last digit: then RSIGstops the running inter–digit time–out and the overall–dialling time–out and stops thescanning as well. This is an example of autonomous release.

[ 7 ]address in bunchThe remaining digits are sent in bunch to ASSS_ASIG.

[ 8 ]disconnectRSIG sends a request to SC DH FMM to release the UCP. This happens in three steps:

1. Join a null pattern to the receiver:

Remember that during the operation the receiver was connected from the PRAMtowards a cluster transmit channel (FETCH). Now a null pattern is sent to the receiver.

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This is done by changing the FETCH from a new PRAM location. This new locationcontains the null pattern for the receiver. In this way the receiver is released.

2. Release the UCP:

Figure 265 : Release UCP

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RT

RT

RT

SCM

DSN

1 2

3 4

RT

RT

RT

RT

ASM

É

É

Receivers

R

É

a

bc

d

e

This is done by calling an OS primitive.

[ a ] On command of the OS, the IDLE pattern is sent via the Transmit channel of theterminal interface to the DSN. After reception of the IDLE pattern during 2consecutive frames, the connection is broken by the DSEs. The idles enter theTERI in the ASM. The hardware reports this to the OS.

[ b ]Because of the idle pattern received by the receive channel at the network side,the cut–through to the transmit channel at the cluster side is broken automatically.Also this event is reported to the OS.

[ c ]Processing of the events: The event in the transmit channel at the cluster side isdetected by the OS which breaks the other cut–through connection between thecorresponding receive channel at the cluster side and the transmit channel at thenetwork side.

[ d ]The event in the receive channel at the network side is also processed and theOS detects that the path that was released, belongs to a duplex connection. Ittakes actions to release the other part of the UCP. This is also done by sendingthe IDLE protocol over the network. The path is released and the same type ofevent is created in the receive channel of the SCM.

[ e ]The PUT TO RAM between the receive channel and a PACKET RAM location isdisconnected automatically.

From this moment on there is no longer a relation between our subscriber and theDTMF receiver.

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When the release of the path was successful, both DHs (in the ASM as well as in theSCM) are informed. OS sends a message to both device handlers (not shown in theoverview figure !).

3. Set the receiver idle:

The receiver is brought to the idle state.

[ 9 ]signalling to call controlThe three digits are sent to CFCS.

6.1.7 Perform B–party analysis / Request DID

Figure 266 : Perform B–party analysis and request DID

CFCS

ASSS_ASIG ARTA

PATED

LSIF

SCALSV

SACELSIF

TRACGCCHAN

SACETRA

1 2

3 4

TRC

A

The B–party’s profile and the DID are retrieved.

[ 1 ]data requestCFCS requests B–party analysis.

The message towards LSIF contains:

– DNET: this code was retrieved from PATED;

– the remaining digits: D5, D6 and D7 in our example.

[ 2 ]data resultsIn chapter 3.4.9 we explained how LSIF uses this information to determine the destination.Via a conversion to DNEH an index is found, and together with the last two digits the correcttuple can be identified. LSIF finds:

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� Equipment Number (EN);

This includes the LCE–identity and the TN of the destination subscriber. The ENuniquely identifies the subscriber within this exchange.

� Terminating Line Class Of Service (TLCOS)

This is the data of the B–party. It contains amongst others:

– Facility indications and allowance flags (Call transfer, ...)

– Access status: Normal line, coinbox, operator, priority line, ...

– Allowed Basic Services and Bearer Capabilities (see also ISDN calls)

� Restriction Match

As explained in the chapter or LSIF, the restriction match checks the Calling PartyCategory (CPC) against the access status (normal line, operator, dataline, coinbox, ...)

The result indicates if the call can continue or results in a CAUSE. With this CAUSEPATED is accessed to define what to do next (see CAUSE analysis). In our examplethe call will continue.

[ 3 ]DID requestCFCS requests the Device Interworking Data (DID). The DID is handled by the TrunkResource Allocator (TRA). Refer to chapter 3.4.11 for more details on the DID.

[ 4 ]DID dataTRA returns the DID results to CFCS.

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6.1.8 Seize B–party / Start ringing phase

Figure 267 : Seize B–party and start ringing phase

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM

ASSS_TSIG

SMD FMM

LCRC DH SSM

SCALSV

ASM (term)ASM (orig)

CGCCHAN

LCHG LCHG

1

2

7,9

8

10

11

13

4

TRC

15

5,12 6

AASSS_TSIG

B

A B

3 14

The B–party’s profile and the DID are retrieved.

[ 1 ]call control to signallingCFCS sends the B–party’s profile to ASSS_ASIG_A.

[ 2 ]joinFor analogue calls the new join information is transmitted to the device handler becausevery soon the UCP between both subscribers will to be connected.

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REMARK: It is possible that the information is queued if the SCM is not yet released.

[ 3 ]signalling to signallingTo set–up the terminating call ASSS_ASIG_A allocates new TACB, which will be labeledfrom now on as ASSS_ASIG_B.

[ 4 ]intra signallingThe ASSS_TSIG of the terminating side is triggered, resulting in the creation of a newTACB, from now on labeled as ASSS_TSIG_B. Depending on the cross–over state, themessage is received in the own ASM or in the mate ASM of the destination subscriber.However in both cases the actions in software remain the same.The message also contains the destination TN to identify the B–party in ASM_B.

Note: If the destination subscriber is busy, a message is returned to ASM_A. There (PA)TED isaccessed with a CAUSE to define how to terminate this call. The result indicates that a busy toneshould be transmitted to the A–party. This tone is retrieved from the tone port (see dial tone) but thistime the connections are established in the terminal interface of the ASM instead of the SCM.

[ 5 ]remove terminal from the origination scanning list.

[ 6 ]select channelASSS_TSIG_B sends a request to the device handler to:

– indicate the device state busy;

– [ 7 ]get cluster handler path

send a command to the hardware to power on the subscriber line;

select a cluster channel towards the ALCN. The identity is also transmitted to theALCN logic (compare with A–party);

– set up a UCP towards ASM_A;

– send ringing tone to the originating subscriber;

– request for ringing current to the B–party;

– relink with CFCS . In the message also the channel identity is returned. CDEdependent a ”wait for answer” is started in ASSS_TSIG_B.

Some of these actions are discussed in more detail below.

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[ 8 ]set up spata pathThe setup of a UCP was also discussed in chapter 3.3.3. The DH_B transmits a BASIC VIAto the DH_A after requesting a spata channel to the OS.Upon receipt of this message in the SMD FMM_A, the latter makes a duplex cut–throughbetween the UCP and the cluster path.

SMD FMM_B connects ringing tone to UCP towards A–party.

The RT is connected to the UCP via a FETCH command.

First, immediate ringing tone is sent to the subscriber (500 ms) The samples for thistone are available in a fixed PRAM location.

Second, after the 500 ms time–out the interrupted ringing tone is sent (e.g: 1 secondtone and 3 seconds silence, ...)

[ 9 ]request ringing activeSMD FMM_B requests ringing current towards the B–party.

The hardware situation at this moment (except for the ringing current) is shown in figure 268.

Figure 268 : Ringing phase

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RT

RT

RT

RT

ASM

DSN

1 2

3 4

RT

RT

RT

RT

ASM

ÉÉ

R

Ring.Gen.

� Request ringing current

To provide the subscribers with ringing current (=RC), there is one RNGF PBA forevery ASM.The main function of the RNGF PBA is to generate a stabilised AC ringing signal inaddition to the DC voltage of the ’a’ and ’b’ wire.One RNGF contains two identical ring circuits and provides a RC source for up to 128subscribers. It can provide asymmetric (the 2 buses serve 64 subscribers each) as wellas symmetric ringing current (the 2 buses are combined to serve 128 subscribers).

a. Hardware

– The RNGF PBA

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The ringing PBA is connected to the cluster link of the own terminal interface andthe cross–over terminal interface (in case of cross–over, the mate processor mustaccess the ring PBA). The processors can send commands to the PBA (viaCH16) to activate or deactivate the circuit.When the circuit is activated, it generates a continuous AC signal. This signal isreceived on all subscriber circuits of all ALCNs, but it is not connected. To connectthe signal (so that the telephone starts ringing), the processor must transmit acommand to the appropriate ALCN to close the switch (relay). The cadence of theRC (e.g: 1 second ringing and 3 seconds silence, ...) is done by opening andclosing (activating and deactivating) the relays.This is clarified in figure 269.

Figure 269 : Switching of RC

RCALCN

...

RNGF

To own TERI

To cross–over TERI

To other ALCNs

Ringing

Generator

Ringbus

CH16 Commands

CH16 Commands

– Ring phases

Let us consider the example of 1 second RC and 3 seconds silence. It is possiblefor the RNGF PBA to send RC to maximum 8 subscribers. This means thatmaximum 8 different subscriber relays are activated.

During the silent phase, however, the relays are deactivated and nobody isreceiving RC. During this phase it is possible to send RC to other subscribers, etc.

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This can be done for 4 phases and the result is shown in figure 270. In this way itis possible to send RC to maximum 32 subscribers.

Figure 270 : Ringing Phases

Phase 1 Phase 1

Phase 2 Phase 2

Phase 3

Phase 4

RCon

off

RCon

off

RCon

off

RCon

off

b. Software

– Ring phases

The switching of the phases is implemented in the software. The DH receives atime out message every 200 ms. In this way it can count the 4 phases with a 200ms resolution.Each time a phase change occurs, the DH opens all the relays of the subscribersreceiving RC and closes the relays of the subscribers belonging to the nextphase.If all 4 phases are empty (no subscribers assigned), then a command is senttowards the RNGF PBA to switch off the ringing generator.

Note: The switching of the relays is called ”dry switching”. This means that the ringing generator isswitched off before the relays are opened and switched on again when the other relays are closed.

– Ringing current request

When the DH wants to send RC to a subscriber, it must assign a phase to thesubscriber. Then the subscriber receives RC according to the phase switchingmechanism explained above.

The phase selection is done according to the flowchart below.

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Figure 271 : Phase selection

Ringing Request

Time left in current phase <400ms

Nbr of assignedsubscribers = 8

NEXT PHASE

Y

N

Y

N

Assign to the selected phase

Connect immediate RC (Activate switches)

All phases checked ?

CAUSE

Y

N

In the above flowchart, one of the actions is: ’Connect immediate RC’. This is when asubscriber is assigned to a phase which is not the current one. In this case the subscriberswitches are closed at any rate, and the normal cadence starts when the subscriber’s phaseis reached.

[ 10 ]channel infoSMD FMM_B replies with the channel information.

[ 11 ]intra signallingASSS_TSIG_B acknowledges the terminating seizure.

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[ 12 ]transmission parametersASSS_TSIB_B initialises receive and transmit values.

[ 13 ]signalling to call controlThe final acknowledgement: linking of the terminating side is complete.

[ 14 ]signalling to signallingAcknowledgement of the seizure of the B–party.

[ 15 ]intra signalingAcknowledgement of the seizure of the B–party.

6.1.9 Activate charging

Figure 272 : Activate charging

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM

SCALSV

ASM (orig)

CGCCHAN

LCHG

12

3

4

5

TRC

A

A B

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The charging information is picked up and a taxation cell is allocated.

In most countries charging is activated at this moment. For more details refer to chapter 8.In this chapter only an overview is given.

[ 1 ] charging request

Charging is activated via a message from CFCS. It is up to the charging FMMs to define thecharging for ”our” subscriber (method, number of pulses, rate, ...). The charging FMMs alsoallocate a taxation cell for the call (1 or more depending on the supplementary services ofthe subscriber). Then the result is sent back to CFCS. The most important informationreceived from charging is the identity of the taxation cell(s).

[ 2 ] request charging information

[ 3 ] send charging information

[ 4 ] request allocation of charging cell

[ 5 ] charging start–up acknowledge

6.1.10 Pass to stable state

Figure 273 : Pass to stable state

CFCS

ASSS_ASIG ARTA

PATEDSCALSV

CGCCHANTRC

A B

1 2

Once the B–party has been seized and the ringing phase has started, the only task leftto do is to wait until the B–party answers. Therefore there is no need for high–level softwareto be active. Remember that CFCS controlled the whole call and kept all the data about thecall in a datazone. At this moment the CFCS passes part of it’s information to the signallingin ASM_A, and part of it’s information to signalling in ASM_B. The application process maythen terminate.

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[ 1 ] [ 2 ] pass to stable stateThe stable call data is passed to signalling.ASSS_ASIG_A stops the overall–dialling time–out.

ASSS_ASIG_A also received the taxation cell identity because it is ASSS_ASIG_A thatwarns the charging FMM about the on–going events, like B–party answer and A–party orB–party hook–on. These events can then be used by the charging FMM to start or stop thecharging.

At this moment we are in stable state which means that the A–party is receiving ringing toneand the destination set is ringing. The A–party and the exchange are both waiting foranswer.

6.1.11 Detect ring trip

Figure 274 : Detect ring trip

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM

ASSS_TSIG

SMD FMM

LCRC DH SSM

SCALSV


CGCCHAN

LCHG LCHG

1

2

3

4

5

7

TRC

BA

A B

6

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When the B–party answers the signalling has to be informed and the charging has tostart.

[ 1 ] ring tripThe detection of answer is the same as the hook–off detection. The hardware reportstowards OS which triggers the LCRC DH SSM_B.

LCRC DH SSM must remove the ringing current as soon as possible. If the subscriber is inthe silent period, the SSM removes the subscriber from the ringing queue. However, if thesubscriber receives ringing current at this moment, the SSM first deactivates the relay beforeremoving the subscriber from the queue.

LCRC DH SSM then reports the ring trip to ASSS_TSIG_B.

[ 2 ] put terminal in busy scan with recall.

[ 3 ] intra signallingASSS_TSIG_B reports the answer to ASSS_ASIG_B.

[ 4 ] joinSMD FMM_B removes the ringing tone and joins the B–party to the UCP.

[ 5 ] request ring idle.

[ 6 ] signalling to signallingASSS_ASIG_B reports the answer to ASSS_ASIG_A.

[ 7 ] charging eventASSS_ASIG_A indicates the answer to charging (e.g. to start the collection of chargingpulses)

ASSS_ASIG_A also cancels the answer time–out.

6.1.12 Stop charging / Release A–party

a. Clear forward (forward release)

If the release of the call is initiated by the A–party we call this a clear forward or aforward release .

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Figure 275 : Stop charging and release A–party

CFCS

ASSS_ASIG

ASSS_TSIG

ARTA

PATED

SMD FMM

LCRC DH SSM

ASSS_TSIG

SMD FMM

LCRC DH SSM

SCALSV


CGCCHAN

LCHG LCHG

1

2,7

5

68

TRC

3,10

9

BA

A B

4,11

When the A–party hooks on, the subscriber has to be released and the charging has tobe stopped.

[ 1 ] hook onLCRC DH SSM_A indicates to ASSS_TSIG_A that the A–party hooked on.

[ 2 ] put terminal in busy scan list

[ 3 ] intra signallingASSS_TSIG_A reports the hook–on to ASSS_ASIG_A.

[ 4 ] signalling to signallingASSS_ASIG_A reports the hook–on to ASSS_ASIG_B and starts a time–out for delayedcongestion tone (e.g. 12 s).

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[ 5 ] intra signallingASSS_ASIG_A indicates the necessary actions to ASSS_TSIG_A:

– release the A–party;

– report the charging event.

[ 6 ] charging eventASSS_TSIG_A reports the hook–on to charging (e.g. to stop the charging).

[ 7 ] remove terminal from busy scan list

[ 8 ] releaseSMD FMM_A executes the release of the UCP and the cluster path.

[ 9 ] return cluster path

(the principles of UCP release were explained in the chapter on the DTMFreceiver release)

put terminal in origination scanning list

The terminal can originate a new call and is powered down.

Also the subscriber state is changed to ’available free’. When the UCP is released, OSsends this event to both DH FMMs (not indicated in the overview figure !).

[ 10 ] intra signallingASSS_TSIG_A acknowledges the release.

[ 11 ] signalling to signallingASSS_ASIG_A indicates the release to ASSS_ASIG_B.

From the COL the software retrieved the information whether or not the subscriber shouldreceive a parking tone (see retrieval of COL before). Depending on this information, twocases are possible:

� Silent parking

ASSS_TSIG_B sends the clear forward to the DH. The latter puts the subscriber in theparking state. The cluster path is released and the line is put in power down. When theB–party replaces the handset, the event is sent to the DH and the subscriber is putavailable free.

� Parking with tone

The ASSS_TSIG_B starts a time–out and sends a request to the DH to connect thistone and to enter the parking state.

If the subscriber replaces the handset within this time–out, then the time–out is stoppedand the DH is triggered to disconnect the tone and put the subscriber available free.

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If the time–out expires, then ASSS_TSIG checks in database if a second tone has tobe connected. If not, the silent parking actions are started.

b. Clear backward

If the release of the call is initiated by the B–party we call this a clear backward or abackward release . Because of the similarity of the scenario (same principle as clearforward), no scenario is given here.

Upon receipt of the called hook–on, ASM_B informs ASM_A. There, charging isinformed because CDE dependent charging can continue, change or be temporarilystopped.Moreover, a reanswer time–out is started to give the B–party the chance to lift thehandset of the same or another set connected to the same line. Three possibilitiesexist:

– A–party hooks on:

The hook–on results in the same actions as the clear forward. Only this time theB–party is available free instead of being put in the parking state.

– Reanswer time–out expires:

ASSS_TSIG_B receives the time–out message. Actions are taken to put theB–party available free and release all the connections and the cluster path.The originating ASM is informed to stop charging and to put the A–party in theparking state until hook–on.

– B–party hooks off again:

The event is translated to REANSWER and the reanswer time–out is stopped.Also the originating ASM is informed to send the event to charging (if the chargingwas modified or stopped, it will resume with the previous charging) Theconversation can continue.

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6.1.13 Release B–party

Figure 276 : Release B–party

CFCS

ASSS_ASIG ARTA

PATED

ASSS_TSIG

SMD FMM

LCRC DH SSM

SCALSV

ASM (term)

CGCCHAN

LCHG

1

2,5

3

4

TRC

B

B

The B–party’s telephonic state is changed to available free.

[ 1 ] hook–onLCRC DH SSM detects that the B–party hooked on.

[ 2 ] intra signallingASSS_TSIG_B reports the hook–on to ASSS_ASIG_B.

[ 3 ] intra signallingASSS_ASIG_B indicates the necessary action to ASSS_TSIG_B:

– release B–party.

[ 4 ] releaseSMD FMM releases the B–party: the cluster path is released and the telephonic state ischanged to available free.

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[ 5 ] intra signallingASSS_TSIG_B acknowledges the release.

6.2 Local call with ISDN subscribers

6.2.1 Example of an ISDN

Figure 277 : Example of an ISDN

S–interface

U–interfaceNT1

subscriber’s premises A1000 A12

ISM

IPTMPRA

ISDN

PABX

IRSU2 Mb/s PCM

IRIM

Ç

Ç

Ç

ÇÇ

Ç

Ç

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a. The S interface

The S–interface has a four wire configuration.It allows to connect up to eight ISDN terminals. The terminals are simply connected indaisy chain.

b. The basic rate access interface

The basic rate access interface is an interface with many names:

– basic rate access (BRA);

– basic access (BA);

– 2B+D interface.

Technically the more interesting name is 2B+D interface, because it sheds some lighton the capacity of the interface: the interface contains two B channels and a D channel.

The B channels are used for any type of circuit switched communication, such as:

– speech;

– circuit switched data transmission;

– video transmission.

The B channels are allocated for the duration of a call. They have a bit rate of 64 kb/seach.

The D channel is used for:

– signalling, for example to set up and release a call;

– packet switched data transmission;

– telemetry.

The signalling information and possibly the data packets are all multiplexed into thesame channel. The D channel has a bit rate of 16 kb/s.

The total bit rate on a BRA interface is thus 2*64 kb/s + 16 kb/s = 144 kb/s.

The line coding on the BRA interface is either 4B3T or 2B1Q.

– With 4B3T 4 binary digits (bits) are converted into 3 ternary digits. As a result thesignalling rate on a BRA is 120 kBaud (144 *3 /4 + control signals).

– With 2B1Q line coding 2 bits are converted into 1 quaternary digit. As a result thesignalling rate on a BRA is 80 kBaud (144 /2 + control signals).

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The BRA interface has a two wire configuration.To provide a full duplex transmission, echo cancellation is used.

c. The primary rate access interface

A primary rate access (PRA) has 30 speech channels (B) and one signalling channel(D). It is therefore called a 30B+D interface. Each channel operates at a bit rate of 64kb/s.

Note: The D channel of a PRA has a bit rate of 64 kb/s, as opposed to the bit rate of the D channelof a BRA, which has a bit rate of 16 kb/s

The bit rate on a PRA is 2.048 Mb/s. The PRA uses a frame of 32 channels, numberedfrom 0 till 31. The channels have the following functions:

channel 0 synchronisation

channel 16 conveys the D channel information

channels 1–15 and 17–31 contain the 30 B channels

A PRA is typically used to connect an ISDN PABX to an exchange. The distancebetween the user and the network is unlimited, provided that regenerators are used.

6.2.2 Overview of the ISDN protocols

Figure 278 : The OSI model for a BRA

B1 entity S entity P entity T entity

LAPD entity

physical entity

speech / video /data (circuit switched) signalling

data(packet switched) telemetry

layer three

layer two

layer one

B2 entity

B1 entity B2 entity

The ISDN standards are compatible with the bottom three layers of the open systemsinterconnection (OSI) reference model. Figure 278 demonstrates this for a BRA.

In layer three, the network layer , you find the entities that represent the two B channels andthree entities for the D channel: the signalling entity, the packet switching entity and thetelemetry entity.

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In layer two, the data link layer , the D channel follows a data link protocol of the high–leveldata link control (HDLC) type. That protocol is called link access protocol on the Dchannel (LAPD) .

In layer one, the physical layer , a frame structure has been defined to convey the bits on aBRA or a PRA. It is only on this level that a distinction between BRA and PRA is made !

The following table compares the OSI definitions with the ITU–T standards.

layer OSI model ITU–T standard

3 network layer Q.931

2 data link layer Q.921

1 physical layer I.430 / I.431

6.2.3 Layer three: the network layer

The network layer performs the routing functions and handles the signalling messages andsignalling procedures.

The signalling at layer three is referred to as digital subscriber signalling one (DSS1) .

Figure 279 : Generic layout of a DSS1 message

protocol discriminator

length ofcall reference

call reference

message type

information element

0 0 0 0

1 byte

optional and repeatable

Figure 279 gives the generic layout of a DSS1 message. It contains the followingcomponents:

� Protocol discriminator

The protocol discriminator indicates the layer three protocol. The most important value hereis H’08 indicating Q.931 user–network call control messages.

� Call reference

The call reference uniquely identifies a call within a logical link connection on auser–network interface. It has no end–to–end significance. This means that the call

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reference value that identifies a call between the A–party and the exchange and the callreference value that identifies the same call between the exchange and the B–party can betotally different.

The call reference is a layer three parameter. It has a length of one byte for a BA and one ortwo bytes for a PRA. The following figure gives possible layouts of the call reference.

The call reference value is allocated by the originator on the user–network interface.Typically this would be the A–party’s telephone set on the first user–network interface andthe exchange on the second user–network interface.

� Message type

The message type is a 7 bit value that indicates the type of DSS1 message, such as set–upmessage, connect message and so on.

� Information element

The real information is carried in a number of information elements.

6.2.4 Layer two: the data link layer

The data link layer performs the error control functions and the flow control functions.

a. Layer two packet layout

Figure 280 : Layer two packet layout

information

flag address control frame checksequence

8 b 16 b N*8 b

flag

16 b 16 b 8 b

layer three

layer two

The packet contains the following fields:

– flag:

The flag is used to separate two messages. It has a fixed layout: B’0111 1110.

– address:

Since there can be up to eight terminals on a BA, each terminal has to be addressablein a unique way. This is achieved with two layer two parameters: the terminal endpointidentifier (TEI) and the service access point identifier (SAPI).

The terminal endpoint identifier (TEI) identifies the physical terminal on a BA. It is anumber from 0 to 127. The values have the following purpose:

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TEI purpose

0 – 63 non–automatic TEI assignment

64 – 126 automatic TEI assignment

127 broadcasting

The values for non–automatic TEI assignment have to be programmed into the ISDNequipment by the user.The values for automatic TEI assignment are dynamically allocated when the first call isstarted from a newly connected terminal.

The service access point identifier (SAPI) identifies the type of call. It is a value from0 to 63 with the following assignment:

SAPI purpose

0 call control part (circuit switched call)

16 packet switched call

63 management call

The combination of the TEI and the SAPI uniquely identifies a data link.

With a SAPI value of 16 the packet switching network can be accessed. This requiresinterworking between the D–channel and the PS network. The System12 module thattakes care of this is the IPTMN.

– control:

The control field contains a sequence number and flow control information. It is used toacknowledge messages or to request retransmission.

– information:

The information is passed by layer three.

– frame check sequence:

The frame check sequence (FCS) is calculated by the sending side and transferredtogether with the message. The receiving side recalculates the FCS and compares thefound value with the FCS value from the message. If they are equal, the message isassumed to be received correctly. If the two values are different, the message isdiscarded.

b. Layer two packet carrying a layer three packet

If a terminal sends a layer three packet, it first passes the packet to layer two. Layertwo then adds a number of fields, as explained in the previous chapter. Eventually the

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packet arrives in the ISM. The packet is passed to the ISS FMM in the form of aSystem12 message. The data part contains the terminal number (TN) and the TEI. Theactual layer two packet, including the layer three cargo, is attached as a user buffer.

c. Layer two packet sequences

Figure 281 : Layer two packet sequences

TEI assignment

data link set–up

receiver ready

TE NTUI

SABME

UA

RR

UI

RR

– TEI assignment

When a terminal requests a TEI, it broadcasts the request to the host. The hostallocates a TEI and sends the TEI value over the broadcast data link to the terminal.Since it is possible that several terminals request a TEI simultaneously, the requestingterminal includes a random number with it’s request. When the host replies, it includesthat number as well. This way each terminal knows which reply it has to use.

– data link set–up

To set up a data link a set asynchronous balanced mode extended (SABME)message is sent. The response is an unnumbered acknowledgement (UA) .

– receiver ready

This layer two message is sent every 10 seconds if a data link is established.

6.2.5 Layer one: the physical layer

The physical layer is described by three types of recommendations:

– electrical recommendations;

– mechanical recommendations;

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– functional recommendations.

According to these recommendations the S interface has a four wire configuration; two wiresin either direction. The wires are connected via an RJ45 plug (8–pins).

6.2.6 Terms and definitions

a. High layer compatibility

The high layer compatibility (HLC) is a value that is used by the terminating side toperform compatibility checks. It represents the type of equipment that is used. Thepurpose is to connect a telephone set to an other telephone set, a facsimile machine toan other facsimile machine and so on. Typical values include:

– telephony;

– facsimile group 2/3;

– facsimile group 4, class I;

– facsimile group 4 class II/III;

– teletex services;

– message handling systems (MHS);

– OSI applications.

b. Low layer compatibility

The low layer compatibility (LLC) is a value that is used by the terminating side toperform compatibility checks. It contains data that describes the lower level of theequipment that is used, such as the information transfer rate, the transfer mode, thenumber of stop bits and data bits, and so on. If provided by the call originator, the LLCis passed to the termination transparently through the ISDN.

c. Bearer capability

The bearer capability indicates the requested bearer service to be provided by thenetwork. Typical possibilities are:

– UNR_DIG

– SPEECH

– AUD_3_1K

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d. Basic service

The basic service (BS) represents the meaningful combinations of a bearer capabilityand a high layer compatibility. The purpose is to allow certain facilities to be defined perbasic service. If all the combinations of BC and HLC were defined, too much datawould be required.

e. Multi–subscriber number

The multi–subscriber number (MSN) allows an operator to assign multiple directorynumbers to the same ISDN subscriber. The subscriber would then program histerminals with different numbers. The purpose can be diverse:

– an A party can dial one of these numbers to arrive at one terminal in particular;

– the ISDN subscriber can request different facilities for the different MSNs;

– the B party will see this MSN as the originator (providing CLIP for B party and noCLIR for A party);

– the MSN can be used for charging to indicate the A party.

For call handling one of the MSNs is declared as the default. This is amongst othersimportant for the location of the subscriber data, which depends on the DNET. All thedata associated with that ISDN subscriber will be stored in the same SACELSIF, even ifhe has MSNs with different DNET values !

f. Subaddress

The subaddress is a number additional to the directory number of a subscriber. Thedirectory number identifies an S interface, whereas a subaddress allows to distinguishbetween different terminals on the same S interface. The subaddress is passedtransparently through the ISDN. If a subscriber wishes to use subaddresses, he has toprogram the value on his equipment.

If an originator passes a subaddress in a set–up message, then at the termination onlythe terminal that has that subaddress will react to the set–up message.

Note: Also the terminals that do not have a subaddress programmed will react !!

g. Interworking directory number

An interworking directory number (IWDN) allows an operator to assign different DNs toan ISDN subscriber. The numbers can only be used in calls terminating at one of thosenumbers. The terminating exchange translates the IWDN into the real DN of theterminating ISDN subscriber and a subaddress and a HLC.

This is the only way an analogue subscriber can reach a particular type of equipment,represented by the HLC, at the terminating subscriber (except for the default HLC).

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It can also be used, in addition to the MSN, to allow an analogue subscriber to reachone of the terminals in particular at the terminating side.

h. User–to–user signalling

User–to–user signalling (UUS) allows an ISDN subscriber to send information (typicallytext or numbers) via the D channel to an other ISDN subscriber. This information canthen be displayed on the telephone set, or used by the B party’s PC.

There are four types of UUS:

– UUS1: UUS during the call set–up and clearing;

– UUS2: UUS during the alerting;

– UUS3: UUS during the active phase of the call;

– UUS4: UUS without allocating a B channel.

6.2.7 Handling of a Q.931 message in S12

Figure 282 : Q931 messages

PROCDH

SIG

PROC

D–CH

D–CH

DSN

ISM

BA

...

...

ILC

MEM

L3L2

L2

L1

L3

L2

L1D

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Figure 282 shows which elements in S12 handle the different layers of the D channel.

� The Q931 is received via the D–channel of the BA. The D–channel is read by the ILC(ISDN Link Controller).This LSI executes the hardware L2 functions: Flag insertion and detection, bit(de)stuffing,FCS (Frame Check Sequence) generation and checking, generate Tx fillers and deleteRx fillers (flags or all ones).

� The ILC writes the message in the memory and informs the processor (interrupt).

� The processor can check the FCS result from the ILC and executes the remaining layer 2functions (handling the sequence numbers, TEI and SAPI, flow control, ...)

� The processor then transmits the message (layer 3 information only!) to the controlelement. Because of the limited size of the PRAM buffers, the processor partitions the Q931message into several parts (if necessary) and transmits them one by one. Again toprovide error free transmission, the packets are labelled and a sequence check (withacknowledge) is used (similar to CCS N7 using FIB,BIB). This principle is not shown infigure 282.

� The packets are received one by one in the DH and transmitted as a whole (A1000 S12message) to the ISS.

� ISS is responsible for the layer 3 actions.

The principle of message sending is the same in the other direction and is therefore notrepeated here.

6.2.8 Local ISDN call overview

The following figure sketches a local call scenario, displaying only the DSS1 messagesexchanged between the subscribers and the exchange. The figure indicates the scenario incase the B party has two terminals (of the requested type).

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Figure 283 : ISDN local call scenario

set–up

call proceed

alert

connect

connect acknowledge

disconnect

release

release complete

A1000 S

12

A dials B’s DN

ringing

conversation

A hooks on

B–party

term_1 term_2

term_1 answers

term_1 hooks on

A party

connect acknowledge

ringing ringing

disconnect

release

release complete

conversation

connect

release

release complete

set–up

alert

alert

call proceed

call proceed

A couple of remarks:

� if the B–party hooks on first, the release of the call is the same as above with the bottom6 messages mirrored;

� the scenario assumes en–bloc sending , where the set–up message contains the fullB–party number (DN and possibly SA). An alternative is overlap sending , where theset–up message contains either only a part of the B–party number or no number at all.The further digits are then sent in information messages;

� the scenario excludes the data link set–up and release.

a. Scenario from A–party towards S12

This scenario is given for a BA.

When a call is generated in an ISDN set, the called DN is entered manually or from theset’s database and a key (or multiple keys) is pressed to start the call setup.

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At this moment the set wants to send a Q931 SETUP message but a BA is normallypowered down. Therefore the subscriber’s equipment (NT1) activates layer 1 (powerup) by sending a fixed pattern.

Then layer 2 is activated via the SABME and UA sequence.

Then the set can transmit the layer 3 Q931 SETUP message. This message containsthe following layer 3 information:

– Call reference;

– Bearer Capability:

This was explained before, in our example it is speech.

– Channel identification:

Identity of the B–channel on the BA (B1 or B2). From the subscriber to the ISMthis field is optional because the host is responsible for the channel assignment(SMD FMM).

– B–party Number (DN) and Subaddress;

– A–party Number (DN) and Subaddress;

– LLC and HLC;

– User to User Signalling (UUS).

The host responds by sending the CALL PROCEEDING backwards. This messagecontains the channel identity (B1 or B2) to be used for this call.

The ALERTING message indicates that the B–party is reached and that the call hasentered the stable phase (ringing).

When the CONNECT is received from the called party the set will acknowledge with aCONNECT–ACK . The connect message can indicate the ’connected address’ whichcan be displayed on the display.

From now on we are in conversation phase.

For an ISDN subscriber the clear forward and clear backward are treated in the sameway because the reanswer possibility does not exist in ISDN. This is because an ISDNsubscriber can use the SUSPEND and RESUME messages to switch to another set ortemporarily suspend a call.

When the subscriber finishes the call, a DISCONNECT is transmitted to the exchange.This is a request to release the call.

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If the request is accepted, the exchange transmits a RELEASE backward, which is alsoacknowledged with RELEASE COMPLETE .

The final actions are the termination of layer 2. This is done by sending the DISC andUA frames.

b. Scenario from S12 towards B–party

This scenario is different compared to the originating scenario because here we useCall Offering. This means that the call is offered to all compatible terminals and oneterminal can connect the call.

This is done by sending a Q931 SETUP Broadcast message (after activating L1 andL2). This message contains the channel identity (B1 or B2).Broadcast means that the message contains the TEI = 127. In this case the message isaccepted by all the terminals. When the terminals check the information (HLC) only thecompatible terminals will respond. When a subaddress is available only that terminalwill respond.In our example, 2 terminals will respond (two telephone sets).

Terminal 1 responds by activating its layer 2 (SABME and UA) and sending the CALLPROCEED. Then the set starts ringing and indicates this via the ALERTING message.

The same procedure is repeated by terminal 2. Both telephone sets use the same callreference but the difference between the message for terminal 1 or terminal 2 is madeby the TEI values. Each set connected to the same BA uses a different TEI.

In our example, terminal 1 answers by sending the CONNECT message.

The host responds by sending the CONNECT ACK back to terminal 1. However, thesecond terminal is still in the alerting phase. Therefore the host sends the RELEASE tothis terminal which responds with a RELEASE COMPLETE . Also the L2 of terminal 2 isdisconnected (DISC and UA).

We are now in conversation phase. The call release scenario is the same as for theoriginating call and is therefore not repeated.

6.2.9 Local ISDN call in detail

Figure 284 gives the call phases for an ISDN local call. The principles for an outgoing orincoming call are the same as explained before (see case study). That is why only the localcall is indicated.

The Q931 messages are also indicated in this figure. Their meaning and contents werealready discussed in the previous paragraphs, so they are not repeated here.

Only some differences with the analogue local call are explained in the following paragraphs.

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The phases are more or less the same, except that for an ISDN subscriber some phases areomitted. This is because of the powerful Q931 signalling system (compatible with CCS N7)which doesn’t need a receiver. These phases are deleted from the scenario (see crosses)but are still visible to clearly indicate the differences with analogue scenarios.

Remark: the A–party Q931 messages are on the left side of the pages and the B–party messagesare printed on the right side.

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Figure 284 : Local Exchange

RELEASE RECEIVER

SUBSCRIBER

SEIZURE



PREFIX ANALYSIS

LOCAL OUTGOING

END OF DIALLING

OUTGOING TK SEIZURE



ANSWER

TERMINATING SEIZURE

PASS TO STABLE STATE

ANSWER

IAM

ACM

ANC


FORWARD RELEASEFORWARD RELEASE

CLF

CLEARRLG


SETUP

CALL PROC

ALERT

CON

ACK

DISC

REL

REL_C

SETUP

CALL PROC

ALERT

CON

ACK

DISC

REL

REL_C

a. Seizure

SETUP

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– The setup contains all the necessary information to start the call. Because all theinformation in the message is digital, there is no need for a receiver to detect thedigits. The dial tone is generated locally in the set.

– Signalling creates a transaction for this call and allocates a transaction control block(see local call).

– SCREENING (figure 285)

Screening applies to ISDN subscribers and to analogue subscribers in case theyare connected to a Mixed Subscriber Module (MSM), Mixed–RSU or ISDNConcentrator (ICON).

Figure 285 : Screening

A–party DN

TN

Translate

Translate

&

DK

OK/NOK

(Default DN/DK)

Screening

Scrn_grp

Scrn_grp

The TN (only 1 TN / BA) and the A–party DN are translated into a screening groupnumber (scrn_grp). Both numbers must be equal to have an ’OK’ condition. At thesame time the DN is translated into the DataKey (DK). This key was mentionedbefore. Each data key (read: Directory Number) can have a different data profile.There is a one to one relation between the DK and the DN, but the DK is easier touse to access database (index instead of the binary search using the DN).

If the A–party DN is not found (E164, PBX number or Private Number [seefacilities]), then the call is REJECTED.

In case the A–party DN is not provided or the screening procedure is not used(depends upon the administration), the TN can be translated into the defaultA–party DN and DK which will be used during the further call setup.

– A cluster path is allocated and connected to the B–channel

– ISS gets the OLCOS from the database using the DK as input.

DNET: used to define the LSSG for this subscriber to access the LSIF data (donelater by CFCS)

Subscriber group

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Calling Party Category = CPC (normal subscriber, coinbox, data line, test call,...)

Charging information

Number of prefix digits required

Facility allowance (abbreviated dialling, hotline, ...)

Indication if CFCS must access the data at ACE level

...

– CFCS is activated. The global scenario can be compared with figure 254, but theaccess to ARTA is not included.CFCS sends a request to LSIF to retrieve the data (the DNET and the digits areused to define the index in the LSIF relations):

Facility related data: abbreviated dialling, full three party service, hotlineinformation, password for subscriber control (SC), ....

Changed number (can be used to send announcement)

Selective scanning list. This is a list of DNs of which the calls can be rejected,different ringing or forward their incoming calls.

Specific ISDN information: CUG information (Closed User Group), UUS (User toUser Signalling), Advice of Charge (AOC), DNs presentation (restrictions andoverride), ...

Basic Service dependent facilities: Call forwarding, Incoming and OutgoingBarring, ... (remember BS=0 for analogue subscribers)

Call Proceed

b. Prefix Analysis

– All the digits were received ’en–bloc’. So all the digits are transmitted towardsPATED. For the input and output of PATED see the case study.

– For an outgoing call the actions were discussed detailed in the case study. For thelocal call we terminate towards an ISDN subscriber. Because this is new, weconsider a local call.

Reception of the remaining digits and release of the receiver are not needed foran ISDN call.

c. Subscriber identification and terminating seizure

– The terminating seizure scenario is similar to that of the analogue call (see alsofigure 249).

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– For the terminating seizure some messages are transferred to the terminatingequipment (in our example only one set responds to the broadcast)

SETUP

Call Proceed

d. Pass to stable state

– Chapter 5.5.1, message [22] mentioned the fact that signalling waits for theALERTING coming from the B–party’s equipment, before sending this alerting eventto CFCS. It is only then that CFCS activates charging and goes stable.

Alerting Alerting

– At this moment the called terminal is ringing and the calling terminal receives RTfrom the exchange.

e. Answer

– Upon answer (CONNECT msg) the RT is disconnected, the through connection isestablished and taxation is started.

Connect Connect

Connect Ack Connect Ack

f. Forward release

Release

Release Com

Disconnect

Release

Release Com

DisconnectStart release actions Stop taxation

B–ch free

B–ch free

All connections are cleared and the subscriber is free again.

6.3 Outgoing / incoming call with CCS N7 signalling

6.3.1 Introduction

Figure 286 shows the situation for an outgoing / incoming call using N7 signalling.

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Figure 286 : Overview Outgoing / Incoming Call

ASM IPTM

SCM

STP

ACE

IPTM

IPTM

ASM

ACE

IPTM

(N7)

N7

N7

Origination Exchange

Destination Exchange

DSN

DSN

12

34

Figures 287 and 288 show the different phases in the outgoing and the incoming exchange.It is left up to the reader to go through the flowcharts. In the subsequent chapters thesephases are discussed in more detail while references will be made to the local call becausemany actions are the same or similar.

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Figure 287 : Originating Exchange

RELEASE RECEIVER

SUBSCRIBER

SEIZURE



PREFIX ANALYSIS

LOCAL OUTGOING

END OF DIALLING

OUTGOING TK SEIZURE



ANSWER

TERMINATING SEIZURE


ANSWER

IAM

ACM

ANC



CLF

CLEARRLG


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Figure 288 : Incoming Exchange

TRUNK

SEIZURE

PREFIX ANALYSIS

LOCAL OUTGOING


OUTGOING TK SEIZURE


ANSWER

TERMINATING SEIZURE


ANSWER

IAM

ACM

ANC



CLF

CLEAR

RLG


ACM

IAM

ACM

ANC ANC

CLF CLF

RLGRLG

6.3.2 CCS N7 overview

Before we continue with the call discussion, some information is given concerning the N7signalling in A1000 S12. For more details we refer to document 770 00438 0590–VHBE.

a. CCS N7 network

It is possible that the N7 signalling messages are sent directly from the outgoingtowards the incoming exchange without an intermediate STP (Signalling Transfer Part).However, to make the call as generic as possible, we will discuss the situation WITH anSTP (see figure 289).

OP = Origination Point, the exchange where the N7 message originates.STP = Signalling Transfer Point, the exchange where the N7 message passes.DP = Destination Point, the exchange where the N7 message terminates.

http://dms.bel.alcatel.be/secure/cgi-bin/osform/dms?osform_template=calldoc.oft&act=HLINK&code=_770/_00/_438/_0590/_vhbe__.pl

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Figure 289 : Outgoing / Incoming Call with N7 (STP)

Speech

N7 N7

OP DP

STP

b. CCS N7 message layout

The CCS N7 system is a message oriented signalling system, which means that all theuser information is placed in one or more N7 messages. A N7 message is called asignal unit .

The CCS N7 system can be divided into two distinct parts (figure 290).

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Figure 290 : CCS N7 structure

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

SIGNALLING LINK FUNCTIONS

SIGNALLING DATA LINK FUNCTIONS

MTP

USER PART

To / From remote exchange

layer 3

layer 2

layer 1

SIGNALLING NETWORK FUNCTIONS

DISCRIMINATION

DISTRIBUTION

ROUTING

Y

N

DPC =own PC

?

– The Message Transfer Part (MTP) is capable of transporting information withouterrors between two end points. This part is common to all N7 users. It is subdividedinto three functional levels (levels 1, 2 and 3).

– A number of different User Parts , which are situated on level 4. Each User Parttakes care of a specific function. E.g: the Telephonic User Part (TUP) is responsiblefor the signalling handling. It uses the MTP to pass the signalling information to theother exchange. Other examples are the ISDN User Part (ISUP), the Taxation UserPart (TAXUP), ...

Besides the User information, the signal unit contains some information to executelayer 2 functions (error detection and correction) and layer 3 functions (routing). The

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message layout is shown in figure 291. Some of the fields will be used in the followingexplanation of how A1000 S12 handles the N7 messages.

Figure 291 : MTP structure

flag CRC message header CIC OPC DPC SSF SI LI FIB FSN BIB BSN flag

flag CRC

message header

CIC OPC DPC SSF SI

LI FIB FSN BIB BSN flag

N*8b8b 16b 12b 14b 4b 7b7b 1b1b4b14b8b 6b 8b

user part

layer three

layer two

layer one

firsttransmitted

bit

– Circuit identification code (CIC)

Since in a N7 environment speech can follow a different path from the signalling,there is a need to be able to indicate the speech trunks unambiguously. This isdone by numbering them. The exchanges at either end of a trunk have to indicatethat trunk with the same number. This number is the circuit identification code(CIC).

– Point Code

Every N7 exchange has a unique 14 bit number: the point code. Whenever anexchange sends a N7 message to an other exchange, it includes its point code asthe Originating Point Code (OPC) and the point code of the other exchange as theDestination Point Code (DPC).An exchange can have one point code per network level.

– Sub Service Field (SSF)

The SSF indicates the network level. It is a 4 bit field, therefor giving 16possibilities. The two least significant bits are not used however, so that only twobits are used effectively. This gives four possibilities:

Sub Service Field network level

00XX international 1

01XX international 2

10XX national 1

11XX national 2

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In practice only international layer 1 and the national level are used. In Belgiumthe local level is used as the network to transport the charging messages(TAXUP).

– Service Indicator (SI)

The SI indicates the type of user part, such as TUP, ISUP, SCCP, and so on.

– Length Indicator (LI)

Per definition the length indicator indicates the number of bytes between the LIfield and the CRC field. However the following possibilities exist:

length indicator purpose name of the signal unit

0 empty message fill in signal unit (FISU)

1 – 2 link status link status signal unit (LSSU)

3 – 62 real length of the user part message signal unit (MSU)

63 user part > 62 B message signal unit (MSU)

– Forward Indicator Bit (FIB)

The FIB is toggled by the sending exchange to indicate start of retransmission.

– Forward Sequence Number (FSN)

The FSN indicates the sequence number of the message. It is allocated by thesending exchange and is used by the receiving exchange to detect missingmessages. The FSN ranges from 0 till 127. Only the messages that contain alayer three message get a new FSN. The other messages repeat the last FSN.

– Backward Indicator Bit (BIB)

The BIB is toggled by the receiving exchange to request retransmission.

– Backward Sequence Number (BSN)

The BSN contains the number of the last message that was received correctly. Itis used by the sending side to know which messages it may deallocate from theretransmission buffer. The BSN ranges from 0 till 127.

– Cyclic Redundancy Check (CRC)

The CRC is calculated by the sending side and transferred together with themessage. The receiving side recalculates the CRC and compares the found valuewith the CRC value from the message. If they are equal the message is assumedto be received correctly. If the two values are different, the message is discarded.

– Flag

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The flag is used to separate two messages. It has a fixed layout: B’0111 1110.

– Header

The header indicates the type of message. The header consists of two 4–bitfields: H1 and H0.

Figure 292 gives an overview of the working of the N7 system. A user part in exchangeA wants to send some information to a user part in exchange B. There is no directsignalling connection between exchange A and exchange B. Therefore, the informationwill be routed via exchange C. The originating exchange (A) is called the OriginationPoint . The destination exchange (B) is called the Destination Point and theintermediate exchange (C) is called the Signalling Transfer Point . It is left up to thereader to understand the flow.

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Figure 292 : Signal Unit flow

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

MTP

USER PART

layer 3

layer 2

layer 1

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

MTP

USER PART

layer 3

layer 2

layer 1

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ

MTP

USER PART

layer 3

layer 2

layer 1

exchange A

exchange C

exchange B

OP DPSTP

DISCRIMINATION

DISTRIBUTION

ROUTING

Y

N

DPC =own PC

?

DISCRIMINATION

DISTRIBUTION

ROUTING

Y

N

DPC =own PC

?

DISCRIMINATION

DISTRIBUTION

ROUTING

Y

N

DPC =own PC

?

6.3.3 Outgoing / incoming N7 call overview

The example below considers only an OP exchange and a DP exchange (figure 293). It isleft up to the reader to extend the example to include an STP, although some informationabout STP N7 handling will be given at the end of the chapter.

The exchanges are shown in more detailed in figure 294 (OP) and figure 296 (DP). The CallHandling software, via the TRC, has selected a speech DTM which uses N7 signalling

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(=bottom DTM in the drawings). The selection of such a trunk was based on therequirements of the calling subscriber (he could have asked for a minimum signallingdependency), and based on the content of the routing tables, as tey are populated by theadministration. The OP will send a message to the DP. To do this, an IPTM/HCCM is selected to transmitthe message via a N7 link.

Note: The connection between the two circuits of the IPTM/HCCM is called a Signalling link . Thepart of this link between the DTMs (CH16) is called the Data link .

Figure 293 : Outgoing / incoming N7 call

Speech

N7

OP DP

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a. Actions in the Origination Point

Figure 294 : Sending a N7 message (OP)

L2(L3)

L1

IPTM/HCCM

L1

DTM

SCALSV

USER PART (ASIG)

routing

CH16

speech

CIC–id

SLS=xxx0

L3

L1

DTM

DHUSER PART (TSIG)

IPP

UCP

DSN

The user part decides to send a message. In our example the user part is TUP. It issituated at the signalling level. The TUP signalling system consists of TUP_ASIG

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(situated in the SCALSV) and TUP_TSIG (situated in the trunk module with the speechtrunk).

The TC DH FMM has selected a trunk channel within this module.

TUP_ASIG delivers the message to the block ”TR/ROUT”. TR stands for ”TRanslate”, which means translating the message from A1000 S12(Chill modes) into TUP modes.ROUT stands for ”ROUTing ”, because we have to find out which signalling link will beused. This function can find the signalling link (LCE–id + TN) for every TN (trunk).

Figure 295 : Message sending

USER PART

ROUTING (L3) TN IDX CIC DPC SSF

IDX .... .....

SLS0 . . . . 15

LCE–id (IPTM/HCCM) TN (N7 link)

TN (Speech Trunk)

key

L2

FLAGS FCSFSN/FIBBSN/BIB

To IPTM/HCCM using LCE–id

To N7 CH16 using TN

Note: Please note that the representation in this figure is a simplified representation !! It in no wayreflects the relations that are used to store this information.

Using the TN of the trunk speech channel, the DPC, CIC, SSF are found to includethem in the N7 message (figure 291). Also the own OPC is filled in. Then also the

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LCE–id of the HCCM or IPTM which handles the link, is found together with the TN ofthe link within the module.

For the LCE–id and TN of the signalling, loadsharing is applied using the 4–bit SLSfield as parameter.

Using the retrieved LCE–id, the N7 message is sent towards the HCCM or IPTM. Therethe correct link is selected using the TN.

Layer 2 adds the FSN, FIB, BSN, BIB, FCS and the FLAGS before the message is puton the signalling link towards the next exchange (L1).

b. Actions in the Destination Point

The message is received via L1 in the HCCM or IPTM of the destination exchange.

L2 checks if the frame is without errors and if the sequence number is correct. If theframe is accepted, L2 delivers it towards L3 discrimination.L2 also delivers the real message length. Remember that if the LI = 63, it means thatthe real length is > 63. In this case L2 receives the real number of bytes from thehardware reception logic.

It is up to the discrimination part to find out if this exchange is DP or STP. This is doneby comparing the own OPC with the received DPC code from the message (also theSSF is used, which indicates whether the type is NAT or INTAL)In our example the exchange is DP (own OPC=DPC) so the message is deliveredtowards distribution.

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Figure 296 : Receiving a N7 message (DP)

L2

discrimination

L1

IPTM/HCCM

L1

DTM

SCALSV

USER PART (ASIG)

CH16

speech

CIC–id

SLS=xxx0

L1

DTM

DHUSER PART (TSIG)

IPP

UCP

DSNdistribution

The distribution part uses the OPC, SSF and bits 5...11 of the CIC to define theLCE–id of the user part DTM.The speech channel is retrieved from bits 0...4 of the CIC code.The SI field indicates the correct user part (TUP in our example).

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Note: The way that the distribution is described is a simplified way. Further it only applies to a normalCIC distribution. If random CICs are used, the distribution function is more complex.

Using the retrieved LCE–id the message is sent to the TUP_TSIG of the destinationspeech DTM. In the DTM the translation part translates the TUP modes into A1000 S12modes.

Figure 297 : Message receiving

USER PART

OPC SSF CIC(bit 5...11)

DISTRIB. (L3)

LCE–id (DTM) TN of trunk (=CIC bits 0...4)

To DTM using LCE–id

key

L2 FLAGS FCSFSN/FIBBSN/BIB

DPC=own OPC

From N7 CH16

DISCRIM.(L3) CHECK DPC/SSF

WITH OWN OPC/SSF DPC<>own OPC

ROUTING (L3)

SI = TUP

c. Actions in a Signalling Transfer Point

In the above example, there was no STP. However, in the case of an STP the HCCM orIPTM L3 will access the L3 routing (see also figure 298 ) This routing is different fromthe routing in the speech DTM, because in an STP it is not possible to use the TN ofthe trunk speech channel to define the outgoing N7 link.

In this case, the DPC and the SSF of the message are used to define the HCCM orIPTM LCE–id and the TN of the N7 link. Also loadsharing is used based upon the SLS.

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The selection mechanism is shown in the figure below.REMARK: The newly selected HCCM/IPTM can be the same (or different) but it isobvious that the outgoing N7 link (CH16) is different from the incoming link.

Figure 298 : Routing in STP

DISTRIB. (L3)

key

L2 FLAGS FCSFSN/FIBBSN/BIB

DPC=own OPC

From N7 CH16

DISCRIM.(L3) CHECK DPC/SSF

WITH OWN OPC

DPC<>own OPC

ROUTING (L3)

DPC SSF IDX

IDX .... .....

SLS

0 . . . . 15

LCE–id (IPTM/HCCM) TN (N7 link)

key

To IPTM/HCCM using LCE–id

To No7 CH16using TN

6.3.4 Outgoing / incoming N7 call in detail

In the next chapters, the call phases are discussed for the outgoing and the incomingexchange. The phases were shown in figures 287 and 288. The call is discussed insequential order, which means that after transmitting the IAM, the discussion continues inthe destination exchange. With the ACM the call continues in the originating exchange.Thus, it may be confusing for the reader to know at all times in which exchange the actionsare taking place. To solve this problem, the title of each chapter indicates whether theactions happen in the originating exchange (O), or in the destination exchange (D).

a. Prefix analysis (O)

All actions from the moment of hook–off until the start of the prefix analysis are ofcourse exactly the same for a local call and an outgoing call because until the prefix

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analysis result is known it is not yet clear whether the call is local or outgoing.Therefore these actions are not repeated here and we start with the prefix analysis. Fora refresh of the actions we refer to the local call.

After the required number of prefix digits have been received, they are transmittedtowards PATED. The input parameters are the same as in the local call (see figure262). The results from PATED are different:

– PATED finds that the call is OUTGOING.

– A ROUTECODE is found, which is used later to define the outgoing direction (seeTRC and TRA)

– Start selection point: indicates the number of digits to be received before trunkselection starts (in our example this is 7, which means that the entire DN is receivedbefore the trunk selection starts).

– Signalling information (second dial tone, ...)

– ... (see local call)

These results are transmitted back to CFCS which informs signalling of the remainingdigits to be received.

The outgoing exchange and the software blocks involved are shown in the figure below.

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Figure 299 : Outgoing exchange

DSN

DH

TUP_TSIG

ROUT

DTM HW

DH

ASM HW

Speech

DH

SIG

DTMF Rec. IPTM

DTM HW

N7 Lk

PATED

TRC TRA

LSIF

CFCS

ACE

MTP

ARTA

SCM

ASM DTM

DTM

TUP_ASIG ASSS_ASIG

ASSS_TSIG

Note: The ACE in the figure in fact represents a number of ACEs, such as the SCALSV, theSACELSIF and the SACETRA.

Note: It is up to the teacher and/or the reader to use the exchange drawings. This means, try toknow at any moment in which module the actions are taking place and also try to indicate theconnections in all the modules and to clear them when necessary (UCPs, tones, cluster connections,...).

b. End of dialling (O)

The result – 4 more digits required – is sent to the SCM.

When all the requested digits have been received they are transmitted towards CFCS.

c. Release receiver (O)

The actions to release the receiver are exactly the same as for the local call.

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d. Outgoing trunk selection (O)

CFCS sends the necessary information towards the TRM (Trunk ResourceManagement). As explained before, it is up to TRM (=TRC + TRA) to define a DTMwith at least one trunk speech channel free.

The following information is sent to TRC:

– ROUTECODE. This routing code was retrieved in PATED and depends upon:

Origin (subscriber or trunk, for trunk the same outgoing signalling type could berequested);

Destination (routing depends upon the dialled prefix);

TOC (priority calls or operators can be routed via high quality trunks);

Time (e.g: different routing during night time);

Circuit or Packet switched call.

– BC (Bearer Capability). A subscriber can request on a per call basis a certain BC forhis call (e.g: bandwidth and quality of the connection) The request for a certain BCresults in release of the call if the request cannot be fulfilled.

– Signalling type: certain services (e.g: for ISDN) can only be provided via a fullydigital signalling (ISUP).

For our example the three parameters are:

Routecode X

BC = speech , default retrieved from DB for analogue subscriber who cannotprovide this information.

Signalling type = any , because BC=speech and no facilities are used.

The selection mechanism was explained in chapter 3.4.10 and is therefore notrepeated here. The result coming back from the TRM is the following:

– Identity of the outgoing DTM which will be used for the speech.

– DID data for the outgoing trunk (time–out values, signalling information (N7, R2, ...),hardware parameters, ...).

All this information is received in CFCS.

e. Outgoing trunk seizure (O)

The outgoing trunk seizure can be compared with the terminating seizure in the case ofan analogue local call (see before). The selected module is contacted and a UCP is

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established between the selected module and the originating module. Also theconnections in the terminal interface are established.

The scenario is the same as in figure 267. The differences are: destination ASM shouldbe replaced by DTM and the actions [1] and [2] are access to TRM instead of LSIF.Also RC and RT are not connected here.

However, for an outgoing call an additional action is required. It is up to the outgoingexchange to inform the remote exchange about the trunk seizure. This is done bysending a seizure. In our example we are using N7, so the seizure means sending anIAM (Initial Address Message). The sending of N7 messages has been explainedbefore.

The IAM contains more information than the seizure indication:

– Entire Called DN ( ”en–bloc” )

– Calling Party Category (normal call)

– A–party DN (optional)

– ...

IAM

f. Seizure (D)

The IAM message is received in the destination exchange. However, it is only after theprefix analysis that the software knows if this is the terminating exchange or a transit. Inour example it will be terminating, so the situation is shown in figure 300.

In the chapter on N7 it was explained that the incoming exchange can retrieve thespeech channel from the N7 message (bits 0...4 of the CIC). In the incoming DTM acluster path is allocated and connected to the speech trunk channel.

For bothway trunks (N7 always), the TRA FMM is informed that the incoming trunk isinvolved in an incoming call and may not be selected for an outgoing call.

CFCS is activated. This FMM has the same functionality as the CFCS for originatingsubscriber calls.

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Figure 300 : Incoming exchange

DSN

DH

TUP_TSIG

ROUT

DTM HW

DH

ASM HW

Speech

IPTM

DTM HW

N7 Lk

PATED

TRC TRA

LSIF

CFCS TUP_ASIG

ACE

MTP

ASMDTM

DTM

ASSS_ASIG

ASSS_TSIG

Note: The ACE in the figure in fact represents a number of ACEs, such as the SCALSV, theSACELSIF and the SACETRA.

g. Prefix analysis (D)

The prefix digits are sent to PATED. In this case all digits are sent to PATED, becausethey were all received ’en–bloc’.

The input parameters for PATED are:

– Digits received in IAM.

– TOC (Calling Party Category: Normal Call received in IAM)

– NPI and NATADDR: E164 and National, received from IAM or filled in by CFCS.

– Sourcecode: Type = trunk and trunk group number retrieved from DB.

– TOD

The result coming from PATED indicates a local call . The parameters provided in thiscase were already discussed in the Local Call chapter and are not repeated here.

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h. Subscriber identification (D)

LSIF is accessed to define the terminating subscriber. The input and the results are thesame as for a local call.

i. Terminating seizure (D)

Here the terminating subscriber module is informed about the call. If the subscriber isfree, all connections are established and the ringing phase is started.

CFCS sends a request to TRM to retrieve the incoming DID.

The scenario starting with the subscriber identification and ending with a positiveacknowledgement towards CFCS is the same as for the local call in figure 267,replacing CFCS by CFCS and the incoming ASM by the DTM.

Now it is also possible to inform the originating exchange about the successful callsetup. This is done by sending the ACM to the originating exchange.

There exist ACM messages with different meanings. The ACM which is sent in ourexample is of the AFC type. In this case the ACM contains the following information:

– Address complete (no more digits required).

– The B–party is Free.

– Charging has to be applied.

At this moment RC is sent to the B–party and RT is sent from the called ASM to theA–party via the connections. We are now in the ringing phase.

ACM

j. Pass to stable (D)

CFCS passes all the stable data to ASSS_ASIG and TUP_ASIG and terminates.

k. Pass to stable (O)

The ACM message is received in TUP_ASIG in the originating exchange.

CFCS is informed and activates the charging.

Then CFCS passes all the stable data to ASSS_ASIG and TUP_ASIG.

At this moment both exchanges are waiting for answer of the B–party.

l. Answer (D)

As soon as the B–party lifts the handset, the RC and RT are removed and the throughconnection is established. It is up to the destination exchange to inform the originatingexchange of this event to start the taxation.

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To do so, ASSS_ASIG sends the answer signal to TUP_ASIG which transmits the N7ANC (ANSWER) message.

The message content indicates:

– ANswer

– with Charge.

ANC

m. Answer (O)

The N7 answer message is received in TUP.SIG which forwards the event toASSS_TSIG. The latter will actually start the taxation. Both subscribers are now inconversation.


n. Forward release (O)

When the A–party finishes the call, it is called a Clear Forward and this means that thecall will be released.

ASSS_ASIG stops the taxation for this call.

Via the DHs all the connections are released and the DTM will send the Clear Forwardevent to the destination exchange. This is done via the message CLF.

CLF

o. Forward release (D)

The CLF is received in the destination exchange, where actions are taken to release allthe connections and make the trunk free again.

The fact that the trunk has become free, is sent towards TRA.

The clear forward message is acknowledged with another N7 message, called RLG(Release Guard).

RLG

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p. Clear (O)

Upon receipt of the RLG the trunk is indicated free again, and TRA is informed.

REMARK:

For ISUP some of the messages have different abbreviations but the main principlesremain the same (in some messages also different (more) parameters are used):

– ANC becomes ANM (Answer Message)

– CLF and CBK become REL (Release)

– RLG becomes RLC (Release Complete)

6.4 Transit N7 call

Figure 301 shows the situation for a transit call using N7 signalling.

Figure 301 : Transit Call

IPTM

ACE

IPTMN7

Transit Exchange

DSN

32

speechIPTM

IPTMN7

speech

Figure 302 gives the different call phases. The actions are all similar to or the same as thoseexplained in the previous chapters (see local and outgoing/incoming call).

Because there is nothing new to explain, it is up to the trainee to make the transit scenario.

Note that a transit exchange is transparent for the signalling when the incoming andoutgoing connections have been established.

REMARK:

A transit exchange should never be confused with a signalling transfer point (STP). A transitexchange is for speech and an STP is for signalling.

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Figure 302 : Transit Exchange

TRUNK

SEIZURE

PREFIX ANALYSIS

LOCAL OUTGOING


OUTGOING TK SEIZURE


ANSWER

TERMINATING SEIZURE


ANSWER

IAM

ACM

ANC



CLF

CLEAR

RLG


ACM

IAM

ACM

ANC ANC

CLF CLF

RLGRLG

6.5 Outgoing / incoming call with CAS/R2 signalling

6.5.1 CAS line signalling

CAS stands for Channel Associated Signalling. In this chapter a brief explanation is given ofthe CAS handling in A1000 S12. However for more details we refer to the correspondingSignalling courses.

CAS is used to transmit and receive line events, in other words line signalling . Thechanges in line states are transmitted in CH16 of a digital PCM connection. For everyspeech trunk a nibble is reserved so a change in line state results in the change of the bitpattern (nibble).To know which nibble belongs to which speech channel, a multiframe structure is used. In

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this way it is possible to send for every speech channel (one speech channel is used for onecall) the line events in the nibble of the dedicated CH16.

Figure 303 shows a PCM channel structure with the CH0 frame alignment pattern. Alsonotice the CRC4 + E–bit which was introduced in the CCITT Blue Books. However theCRC4 multiframe structure (not shown here) may not be confused with the CAS multiframestructure.

The CAS multiframe structure is shown in figure 304. The ”first” CH16 contains themultiframe alignment pattern and the remaining fifteen CH16s each contain the CAS bits fortwo speech channels.

Figure 303 : PCM frame alignment.

ÍÍÍÍÍÍÍÍ

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

0 1 2 3 4 5 6 7 8 9 10 3130292827262524232221

MULTIFRAME (2ms)

FRAME (125 µs)

Channel TS (3.9 µs)

(EVEN frames)

(ODD frames)

0 0 01 1 1 1

1

C

YC N N N N N

Frame alignment pattern

CRC4 + synchronisation

National use + E–bit

Remote Junction Alarm (RJA)

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Figure 304 : CAS multiframe structure

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15MULTIFRAME (2ms)

0 0 Y0 1 1 10

b c bd a c da

Multiframe AlignmentPattern

Multiframe align. alarm

for CH1 for CH17

a,b,c,d = CAS information

CH16

b c bd a c da

for CH2 for CH18

CH16

b c bd a c da

for CH15 for CH31

CH16

.

.

.

.

CH16

� Working principle

The CAS line signalling is sent and received by the trunk hardware. Figure 305 showsthe principle.

[ a ]The processor in the DTM wants to send a CAS line event to a remote exchange. Thenew bit values (abcd) are transmitted towards the processor of the trunk hardware.

REMARK: This does not apply to the DTUA, because it uses only one processor.

[ b ]The processor copies the abcd bit values into the CAS memory. The lay–out of this

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memory is easy to understand. It contains 16 adjacent memory locations (words), eachlocation being the CH16 content for transmission in the multiframe (=16 frames).

[ c ]If the hardware is initialised for CAS, it will fetch the correct word (=CH16 content) intothe correct frame.This is repeated for as long as CAS is applicable.

REMARK: If the DTM is not initialised for CAS, it will not execute the above mentionedprocedure. In this case CH16 can be used for speech or CCS (Common ChannelSignalling).

As long as the CAS bits are not changed by the software, the hardware keeps sendingthe same bit values in CH16 of each multiframe.

[ d ]This is the reception of a CAS line signalling event. Every CH16 is written in a receivebuffer(in memory) on 16 consecutive locations (one specific CH16 in the multiframestructure will overwrite the same location, multiframe after multiframe). If the received bits have changed, the hardware takes no action.

[ e ]It is up to the processor to check the received CAS bits with the previous value(therefore the processor checks and copies the CAS buffer on a regular basis).

[ f ]If a mismatch is encountered, the processor sends the CAS line event towards the CEprocessor.

Figure 306 shows the relevant software blocks in the DTM control element. The CASevents are transmitted to and received from the hardware by means of the DeviceHandler (DTM.DH). The events were triggered by or reported to the Signalling level,which is responsible for the line signalling (=R2.SIG).

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Figure 305 : CAS handling

CAS MEM

PROCDH

SIG

PROC

CH16

CH16

DSN

a

b,e

c

d

f

DTM

Figure 306 : CAS software

SIG

DH

=R2.SIG

=DTM.DH

DTM.CE

To/From DTM HW trunk processor

CAS Line Events

6.5.2 R2 register signalling

The MF–R2 register signalling system sends MF codes during the register phase. Totransmit the digits to a remote exchange, a combination of 2 frequencies out of 6 is used.This frequency combination is sent in the speech channel from a sender towards thereceiver in the next exchange and vice versa.

There are 2 groups of 6 frequencies. One group is used for the Forward direction, the otherfor the Backward direction (see figure 307).

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Figure 307 : R2 signalling

Forward MF/R2

Backward MF/R2

Outgoing Exchange

Incoming Exchange

2 freq. out of 6

f1...f6

2 freq. out of 6

f’1...f’6

Forward: signals sent from the outgoing to the incoming exchange.

Backward: signals sent from the incoming to the outgoing exchange.

Two frequencies out of six makes a total of 15 combinations . This is multiplied by twobecause of the two groups (see figure 308).

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Figure 308 : R2 registers signals

SIGNAL GROUP I (In response to A1) GROUP II (In response to A3/A5) MEANING MEANING

1 DIGIT 1 NORMAL SUBSCRIBER2 DIGIT 2 PRIORITY CALL3 DIGIT 3 MAINTENANCE EQUIPMENT CALL4 DIGIT 4 SPARE5 DIGIT 5 OPERATOR CALL6 DIGIT 6 DATA TRANSMISSION CALL7 DIGIT 7 SUBSCRIBER CALL8 DIGIT 8 SPARE9 DIGIT 9 SPARE10 DIGIT 10 OPERATOR CALL11 ACCESS TO OPERATOR SPARE12 ACCESS TO DELAY OPERATOR SPARE13 ACCESS TO MAINTENANCE

EQUIPMENT SPARE14 INSERT HALF ECHO SUPPRESSOR

(Only for very long lines) SPARE15 END OF PULSING SPARE

SIGNAL GROUP A GROUP B MEANING MEANING

1 SEND NEXT DIGIT (n+1) SPARE2 SEND LAST BUT 1 DIGIT (n–1) TRANSFERRED SUBSCRIBER3 CHANGE OVER TO B SERIES SUBSCRIBER BUSY4 CONGESTION CONGESTION5 SEND NATURE OF ORIGINATOR UNALLOCATED SUBSCRIBER/

SWITCHING STAGE NOT WIRED6 SET–UP SPEECH CONDITIONS SUBSCRIBER FREE WITH CALL

CHARGING7 SEND DIGIT (n–2) SUBSCRIBER FREE WITHOUT

CALL CHARGING8 SEND DIGIT (n–3) SUBSCRIBER LINE OUT OF ORDER9 SPARE SPARE10 SPARE SPARE11 SEND INTERNATIONAL TRANSIT

INDICATION SPARE12 SEND LANGUAGE OR

DISCRIMINATING DIGIT SPARE13 SEND CODE OF INTERNATIONAL

TRANSIT EXCHANGE SPARE14 SPARE (ECHO SUPPRESSOR) SPARE15 CONGESTION SPARE

FORWARD

INTERNAT. USE

NAT. USE

BACKWARD

INTERNAT. USE

NAT. USE

The MF–R2 signalling system is compelled . Compelled means that every action(appearance and disappearance of the MF frequency code) is acknowledged by the remoteexchange in the following way:

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– Exchange A starts sending the MF code (Forward)– Exchange B detects this MF code.– Exchange B starts sending the MF code (Backward)– Exchange A detects this MF code.– Exchange A stops sending the MF code (Forward)– Exchange B detects the MF code disappearance.– Exchange B stops sending the MF code (Backward)– Exchange A detects the MF code disappearance.

� Implementation in A1000 S12

The MF–R2 senders / receivers are implemented in the A1000 S12 SCM. The hardware partof the SCM generates 15 forward and 15 backward register signals. Each signal is sent in afixed channel and enters the terminal interface receive port. From there the channels are ina PUT TO RAM status to 30 consecutive PRAM locations (all this is done at initialisation ofthe SCM). If a register signal has to be transmitted, a connection is made between thecorresponding PRAM location and the transmit channel of the UCP (the UCP is furtherconnected to the outgoing speech channel in the DTM)

If the MF code is disconnected, then the connection (FETCH) is moved from an MF codePRAM location towards a location which contains the quiet pattern, otherwise rubbish is sentto the remote receiver.

All this is illustrated in figures 309 and 310. The latter shows also the connection of thereceiver. This principle was already explained for the local call, because it is the same for aMF receiver and a DTMF receiver, although in both cases the hardware will use differentfilters.

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Figure 309 : Outgoing / Incoming exchange for R2

DSN

DH

SIG

DTM HW

DH

SIG

MF Rx/Tx.

DSN

DH

SIG

DTM HW

Speech

DH

SIG

MF Rx/Tx.

MF

MF

ACEs ACEs

DTM

SCM SCM

DTM

outgoing exchange incoming exchange

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Figure 310 : R2 sender receiver

DH

SIG

MF SENDER

RECEIVER

R2FORWARD SIGNALS

R2BACKWARD SIGNALS

Quiet pattern

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Figure 311 : Register signalling

RSIG

SC DH

a d e h

RSIG

SC DH

gfcb

a

c

e

g

aForward

Backward

Figure 311 describes the MF sending mechanism in A1000 S12. The software involvedis the DH and SIG of the SCM.

[ a ]The RSIG calls the DH to make a connection between the transmit channel of the UCPand the PRAM location corresponding to the forward register signal. The register signalis then transmitted to the destination receiver.

[ b ]In the destination exchange the signal is detected by the DH and reported to the RSIG(e.g: the first digit).

[ c ]RSIG stores the digit and calls the DH to start sending the backward signal: ’Send NextDigit’.

[ d ]The backward signal is detected and reported to RSIG.

[ e ]Now the RSIG calls the DH to disconnect the MF code (FETCH quiet pattern).

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[ f ]The disappearance of the forward signal is detected in the next exchange and reportedto RSIG.

[ g ]The backward signal is also disconnected.

[ h ]The disappearance of the backward signal is detected, so RSIG can order the nextforward signal to be transmitted (start again at (a) ).

6.5.3 Outgoing / incoming R2 call overview

Figures 312 and 313 give an overview of the call phases for an outgoing / incoming callusing R2 signalling. If you compare these drawings with these of the N7 call, you will noticethe similarity between them. They differ only with respect to the limitation of the R2 signallingcompared to the N7 signalling. The additional new blocks are indicated in the followingpattern:ÍÍÍÍÍÍ

In the following paragraphs, only some remarks and differences are given for some of thecall phases, because all the other necessary information to understand the call was alreadygiven in the case study.

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Figure 312 : Outgoing / Incoming Call using R2 (A)

RELEASE RECEIVER

SUBSCRIBER

SEIZURE



PREFIX ANALYSIS

OUTGOING

END OF DIALLING

OUTGOING TK SEIZURE

OUTGOING TK SELECTIONSEIZURE

TRUNK

SEIZURE

PREFIX ANALYSIS

LOCAL

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

REGISTER PHASE

SEIZ. ACK

D1NEXTD2

NEXTD3

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

REGISTER PHASE

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

REGISTER PHASE

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

REGISTER PHASE

NEXT

D4NEXTD5

NEXT

D7

.

..

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Figure 313 : Outgoing / Incoming Call using R2 (B)


ANSWER


FORWARD RELEASE

CLEAR

TERMINATING SEIZURE


ANSWER

FORWARD RELEASE


ANSWER

CHANGE TO B

NORMAL SUB.

SUB.FREE

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

RELEASE

ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ

RELEASE

CLF

RLG

6.5.4 Outgoing / incoming R2 call in detail

Note: The title of each chapter indicates whether the actions happen in the originating exchange (O),or in the destination exchange (D).

Note: The line signalling (CAS) events are printed in dotted lines and the register signalling (MF–R2)is printed in normal lines.

a. Prefix analysis (O)

PATED finds out that the call is outgoing and also retrieves the requested number ofdigits before the trunk selection. It is possible that after the outgoing trunk selectionmore digits are needed from the incoming side to obtain the complete number.However, the digits collected thus far can be sent out.

b. End of dialling + Release receiver (O)

c. Outgoing trunk selection (O)

CFCS receives the identity of a DTM which uses R2 signalling.

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d. Outgoing trunk seizure (O)

Because the selected DTM uses R2 signalling, the DTM will access ARTA (cf. localcall) for the selection of an MF sender receiver. In the Tx direction a quiet pattern isconnected. In the DTM a duplex connection is established.

Then the outgoing seizure (CAS) is transmitted from the R2.SIG.

Seizure

e. Seizure (D)

The incoming DTM knows the identity of the incoming speech channel. For N7 theidentity is indicated in the CIC and for CAS indicated by the ’CH16 number’ within themultiframe).

The specified trunk channel is indicated busy and the seizure is acknowledged.

Seizure acknowledge

Also in the destination exchange an MF sender / receiver is selected and connected tothe speech trunk. The sender also transmits quiet pattern and the receiver is waiting forthe first digit.

f. Register phase (O)

This part is different compared to the N7 call. This is because N7 transmits the seizureand the digits in one message. Here we still have to transmit the dialled digits. Theprinciple of MF sending receiving was explained in chapter 6.5.2.

The receiver is connected to receive the backward signals.

The digits were transmitted to the RSIG from where they are transmitted one by one.

Digit 1

g. Register phase (D)

Upon receipt the RSIG sends the MF signal: ’SEND NEXT DIGIT’ until the requestednumber of prefix digits have been received.

Next

Digit 2

Digit 3

Next

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h. Prefix Analysis (D)

The result is local call

Next

Digit 4

Digit 7

Next...

i. Subscriber identification (D)

j. Terminating seizure (D)

The called ASM is contacted to check if the B–party is free and to connect the ASM(UCP + cluster path)

k. Release receiver (D)

CFCS can always request additional information. For example:

– A–party number for malicious call (A9)

– Calling Party Category (A5)

– ...

Also the address complete message must be transmitted as does the signal indicatingthat the B–party is free. However this is a signal of the second group (II) of MF signals.This is done by first sending the signal ’CHANGE TO B SERIES (A3)’. Now theoriginating exchange must answer with a forward signal. Usually this will be the CallingParty Category signal. The register phase is closed by the backward signal’SUBSCRIBER FREE WITH CHARGING’.

Change to B

Normal Sub.

Sub. Free

When the receiver is released actions are taken to connect the DTM trunk to thesubscriber UCP and in the ASM RT and RC is activated.

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According to the DID information, the full joining can be delayed until answer oraddress complete.

l. Release receiver (O)

Also in this exchange the subscriber is connected to the trunk channel.

m. Pass to stable phase (O)

n. Pass to stable phase (D)

o. Answer (D)

Disconnect RT and RC and send ANSWER to the originating exchange to starttaxation.

Answer

p. Answer (O)

Start taxation.


q. Forward release (O)

The actions are the same as for the No7 call. Also Clear Forward (CLF) and ReleaseGuard (RLG) are transmitted. However, these messages are CAS line signalling andtherefore transmitted in the CH16 multiframe.

CLF

r. Forward release (D)

RLG

s. Clear (O) (D)

All connections are cleared and the trunk is free again.

ASSIGNMENT: Try to map all the CAS/R2 signals onto the No7 messages (IAM = ?, ...).

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7. FACILITY HANDLING

7.1 Overview of some of the supplementary services

Supplementary services exist in a wide variety. The list below gives an overview of the mostimportant supplementary services. Some of the services are only available for analoguesubscribers while others are only available for ISDN subscribers and some are available forboth. It is beyond the scope of this document to give a detailed explanation of these servicesand their availability.

In the next chapters some of the services are used to explain the implementation in A1000S12.

� Abbreviated Address (AA)

Allows a user to make a call by sending a short code instead of the complete number.

� Add–On Conference (CONF)

Provides a user with the ability to set up a multi–connection call, i.e. a simultaneouscommunication between more than two parties.

� Advice of Charge (AOC)

The possibility for a user to receive information about the charging rates at call setuptime and possible change of charging rates during the call.

� Alarm Call (AC)

This supplementary service allows the served user to order alarm calls to be made tohis line at times specified in advance by the user.

� Call Deflection (CD)

Allows the called user to respond to an incoming call offered by the network byrequesting redirection of that call to another address specified in the response. This ispossible before or after the alerting starts.

� Call Forwarding Busy (CFB)

Permits a served user to have the network send all incoming calls, or just thoseassociated with a specified basic service, which meet busy and are addressed to theserved user’s ISDN number, to another number. The served user’s originating serviceis unaffected.The busy condition can be detected by the network or indicated by the subscriber. Thisclassification is called:

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– NDUB = Network Defined User Busy

– UDUB = User Defined User Busy

� Call Forwarding to Fixed Announcements (CFFA)

Permits a served user to have the network send all incoming calls carrying speechinformation addressed to the served user’s ISDN number to a fixed announcement.The served user’s originating service is unaffected. If this service is activated, callscarrying speech information are forwarded no matter what the condition of thetermination is.

� Call Forwarding No Reply (CFNR)

Permits a served user to have the network send all incoming calls or just thoseassociated with a specified basic service, which meet No Reply and are addressed tothe served user’s ISDN number, to another number. The served user’s originatingservice is unaffected.

� Call Forwarding Unconditional (CFU)

Permits a served user to have the network send all incoming calls or just thoseassociated with a specified basic service, addressed to the served user’s ISDNnumber, to another number. The served user’s originating service is unaffected. If CallForwarding Unconditional is activated, calls are forwarded no matter what the state ofthe termination is. It can be fixed (operator command) or variable (programmed by thesubscriber).

� Call Hold (HOLD)

Allows a user to interrupt communications on an existing call and then subsequently, ifdesired:

– re–establish communications

– make an additional call to another user, switch from one call to another as required(privacy being provided between the two calls), and/or release one call and return tothe other.

� Call Pick–up (CPU)

Enables the served user to pick up a call alerting at another terminal within apredefined group, eg. Centrex. The user may subscribe to Group Call Pick–up or both.

� Call Transfer (CT)

Enables a user to transfer an established (i.e. active) call to another user. The serveduser must be the called user of at least one of the calls. (i.e. at least one of the callsmust be incoming). For users within a BC network, this service differs from the Call

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Diversion supplementary services in that the Call Diversion services deal only withincoming calls that have not yet reached the “fully established” state, whereas in thecase of Call Transfer an established end–to–end connection exists.

� Call Waiting (CW)

Permits a subscriber to be notified of an incoming call with an indication that nointerface information channel is available. The user then has the choice of accepting,rejecting or ignoring the waiting call.

� Calling Line Identification Presentation (CLIP)

Makes it possible for the called party to receive identification of the calling party.

� Calling Line Identification Restriction (CLIR)

Enables the calling party to restrict presentation of its number to the called party.

� Closed User Group (CUG)

Enables users to form groups, to and from which access is restricted. A specific usermay be a member of one or more CUGs. Members of a specific CUG cancommunicate among themselves but not with users outside the group. Specific CUGmembers can have additional capabilities that allow them to originate calls outside thegroup, and/or to receive calls from outside the group.

� Coinbox (CB)

Allows charging information related to outgoing calls to be transmitted to a terminal(coin box) for the purpose of immediate charging fee payment.

� Completion of Calls to Busy Subscriber (CCBS)

Enables a calling user A, encountering a busy destination B, to have the call completedwhen the busy destination B becomes not busy, without having to make a new callattempt.

� Completion of Calls on No Reply (CCNR)

Enables a calling user A, encountering a busy destination B, to be notified when thedestination B becomes not busy after having terminated an active call and to have theservice provider reinitiate the call to the specified destination B.

� Connected Line Identification Presentation (COLP)

Provides the ability to indicate the ISDN number of the connected line with possibleadditional address information to the calling party when the call is established.

� Connected Line Identification Restriction (COLR)

Offered to the connected party to restrict presentation of the connected party’sISDN–number and subaddress information (if any), to the calling party.

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� Credit Card Calling (CRED) – Credit Calling – IN service

Allows the automatic charging of a call to a particular account not associated with thesubscriber line on which the call originates. The use of an Account Number (AN), incombination with a confidential code, permits the Served User to charge calls to anaccount, which may either be associated with a particular connection to the network(ISDN number) or independent of any physical network termination.

� Credit Card Validation (CCV) – IN service

Validates Credit Cards issued by Credit Card companies and Bank Cards issued byBanks. The validation must be based on an agreement between the Administration andCredit Card companies and Banks.

� Direct Dialling In (DDI)

Enables a user to call directly another user on an ISPBX or other private systemwithout attendant intervention.

� Emergency Call Service (EMERG)

Enables the termination of emergency calls in predetermined installations all over thecountry. Any customer who calls an emergency number will be connected to apredetermined installation. Different numbers will be allocated for different purposes,e.g. police, fire department or medical personnel.

� Fixed Destination Call (FDC)

Allows a user to make a call to a number, nominated by the user, without sendingaddress information to the network.

� General Deactivation (GD)

Allows the user to deactivate certain supplementary services which he has subscribedto.

� Green Numbers (GN) – IN service

Allows the Served User having one or several installations to be reached from all partsof the country with a Green Number and to be charged for these calls.

� Group Call Pick–up (G–CPU)

Invoking this service allows, the served user to pick–up any call alerting at one of theterminals in the group.

� Home Meter (HM)

Call charge units being added to the served user’s meter in the network are alsoregistered on a call charge meter at the subscriber’s premises.

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� Incoming Call Barring (ICB)

Makes it possible for a subscriber to prevent all incoming calls to his access/line or justthose associated with a specific basic service. The ability of the served user to originatecalls remains unaffected.

� Individual Call Pick–up (I–CPU)

To pick up a call using I–CPU, the served user must specify the ISDN number (E.164 orPNP number) of the terminal at which the call is alerting.

� Interception of Calls (INTCP)

When call attempts or supplementary service manipulations for some reason do notgive the expected response, the calling or served user is given information on thereason for the unsuccessful outcome.

� Line Hunting (LH)

Enables the automatic selection of a free information channel on an access from agroup of accesses servicing a subscriber, on receipt of a call to that subscriber’s LineHunting number (LH–number) or Universal Access Number (UAN).

� Malicious Call Identification (MCI)

Enables a user to request that the source of an incoming call be identified andregistered in the network.

� Meet–Me Conference (MMC)

Provides a user with the ability to arrange for a call between more than two participantswith all participants accessing conference bridge.

� Multiple Subscriber Number (MSN)

Allows multiple ISDN numbers to be assigned to a single interface. Each number canbe given a different data profile.

� Outgoing Call Barring (OCB)

Makes it possible for a subscriber to prevent all outgoing calls or just those associatedwith a specific basic service, which are intended to be originated from his access. Theability of the served user to receive calls remains unaffected. The ability of the serveduser to set up emergency calls also remains unaffected.

� Priority (PRI)

Provision is made to give preferential treatment to calls originating from and/oraddressed to certain numbers for call establishment.

� Private Numbering Plan (PNP)

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Allows a Private Telecommunication Network (PTN) Operator to define a PrivateNumbering Plan (PNP) with a different structure than the public numbering plan; toidentify extensions in the PTN, the Operator may give each extension in the PTN anindividual private number. Calls between different extensions in the PTN can beestablished over the public ISDN by using PNP.

� Queue Service (QS)

Enables the called party to have incoming calls placed in a queue when the calledparty’s capability is in a busy state.

� Reverse Charging (REV)

A service allowing the served (called) user to be charged for some or all calls. Onlyusage–based charging may be charged to the called party.

� Subaddressing (SUB)

Allows the called (served) user to expand his addressing capacity beyond the onegiven by the ISDN number.

� Televoting (TVOT) – IN service

A supplementary service that makes it possible for the subscriber to record the numberof calls to one or more specific TVOT–numbers. It is possible to forward some or allcalls to a voice response system or an operator.

� Terminal Portability (TP)

Allows an ISDN user to move a terminal from one socket to another or to move a callfrom one terminal to another within one basic access, during the active state of a call.

� Three Party Service (3 PTY)

Enables a user to establish a Three–Party Conversation i.e. a simultaneouscommunication between the served user and two other parties.

� Universal Access Number (UAN) – IN service

A served user with several installations in different parts of the country can be reachedfrom anywhere in the country by a calling user dialling one given number. Calls fromsubscribers in a predetermined area will be routed to installations chosen (with certainrestrictions) for that area by the Served User.

� User to User Signalling (UUS)

Allows an ISDN user to send/receive information to/from another ISDN user over thesignalling channel in association with a call to the other ISDN user.

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7.2 Facility handling model.

7.2.1 General structure

Supplementary services exist in a wide variety. From an implementation point of view it isappropriate and even necessary to split the set of supplementary services into a number ofgroups:

� Services which can be handled within the context of the call, during the call setup phaseand requiring no complex additional logic.

The required logic for this type of services will be handled by the existing common callhandling software.

� Services which can be handled within the context of the call, but outside the call setupphase or requiring complex additional logic.

Since the actions required by the service have to be executed outside the call setupphase, or because they require too complex scenarios to be implemented in theexisting common call handling software, either additional functionalities are neededwithin the call handling software, or the service has to be handled by the signallingmodules (when those services are closely related to the protocol).

� Services which include multiple parties (three or more)

These services will be handled by some dedicated functionalities of the existing callhandling software.

� User profile manipulation

The manipulation of the user profile by the user himself (user control) can be definedeither as an inidividual supplementary service or as an option of another supplementaryservice.Since user profile update is a very specific call type which does not fit in with the twoparty call concept, again the treatment has to be done by some dedicatedfunctionalities of the call handling software.

The handling of supplementary services can be handled on two locations in A1000–S12:

a. Signalling

Some supplementary services are treated by SIG. When a user invokes such a service,it has to be checked whether the user has subscribed to the service. The class marksbelong to the subscriber’s profile data.

E.g: Call Hold, Call Waiting, ...

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b. Call Control

In chapter 3.4.6 you learned that CFCS is a multiprocess FMM. When we talk aboutsupplementary services it is interesting to know a little bit more about the CFCSenvironment.

In CFCS more and more functions have to be performed which are project specific. Themost important features of this kind are abbreviated dialling, call diversion, keypadfacilities, signalling requirements and allowance checks.

7.2.2 Call and Facility Control System (CFCS) architecture

CFCS can execute:

– All classes that can be executed by CFCS.

– Call Deflection (CD), after Alert.

– CFNR

– ...

CFCS FMM is implemented as a multiprocess FMM with a number of linked procedures(CDE). Whenever the supervisory process of the CFCS FMM receives an activationmessage, an application process is created.

The CDE nature of supplementary services implies that the CFCS has to be a Shell BasedSystem (SBS) (see chapter 3.2.1.e.).

The linked procedures are also called ”SW entities”. Each entity has its specified task toperform. This task is only a part of the complete scenario. It is not the intention to have anentity that handles a specific supplementary service.

Not all the entities are linked to the FMM. Some of them can be accommodated in one ormore CDE SSM(s).

Functions of some of the entities :

� When a service is requested, one of the entities will decide at any moment what to donext. It will link all the necessary entities (by calling them one by one) together tocomplete the service.

� To determine which services can be invoked by a served and how this can be done.

� Execute the call completion of a 2 party call setup as part of a supplementary service.This function depends on the required service and is therefore CDE.

� CDE charging

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� To handle the CDE part of the stable data.

� A lock function to prevent concurrent data changes

� To allocate a conference bridge by sending a request to ARTA.

� ...

The functions of some of the common entities are:

� To retrieve data of a user.

� Interface towards signalling to request digits,...

� Interface towards PATED.

� Terminating seizure: to treat terminating line or trunk seizure, to set up a path.

� Common charging interface

� To handle the common part of the stable call data

� To handle the release of all resources in a basic call

� To handle the connection of a tone or announcement

� Interface towards the Dynamic Data Manager (DDM, see later)

� ...

The above list of functions makes it clear that the common entities can also be used forother purposes than call setup.E.g: Interface towards PATED to analyse the stimuli for the invocation of a service.The condition is that they are all common.

7.3 Supplementary service data structures.

Remember from chapter ’3.4.9 Subscriber analysis’ that most of the subscriber data isstored at LSIF level. This subscriber data can be subdivided into semi permanent data anddynamic data. The following chapters expand on these two types of data.

7.3.1 Semi permanent data

The semi permanent data, also called Low Penetration Data, is the part of the subscriberprofile that has a long life–span. It gives a description of all services, applicable to thissubscriber. For each service a subscriber is allowed to use, we find here all necessaryparameters in order to handle the service.

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For example: if a subscriber has a call forwarding facility, then the semi permanent dataindicates what kind of call forwarding it is and possibly to which DN a call is forwarded.

a. Location of the semi permanent data

Figure 314 : Location of the semi permanent data

ISSS

LSIF DDM

CFCS

PATED

PNP_XL

SACELSIF

SACEBCG

SCALSV

TCE

DNET

BCG_id

PABX_id

DDM

SACEPBX

DDMPARM

ASSSTSIG

ASSSASIG

PABX_id

PABX_id

Figure 314 gives an overview of the semi permanent data of normal subscribers,PABX lines and BCG users.

– semi permanent data of normal subscribers

The semi permanent data of normal subscribers is stored in the SACELSIF. This ACEworks in an active / stand–by configuration. Since the semi permanent data is fairlyimportant, both ACEs, active and stand–by, contain that data. The semi permanentdata is therefore replicated over the two ACEs.

Since in an exchange you can have a number of SACELSIF pairs, it is important to findthe correct one. Correct means, the SACELSIF that handles the data of the subscriberthat is analysed. The choice of SACELSIF is made with the DNET of the subscriber.This applies to both originating and terminating subcribers. As in any active / stand–byconfiguration, the active ACE will normally be accessed.

The subscriber data is retrieved by the Local Subscriber Identification (LSIF) FMM.

– semi permanent data of PABX lines

If the DN that is analysed belongs to a PABX, then at some point the PABX identity isretrieved. This can happen in the TCE, where the PABX identity may be indicated in theOLCOS data, or in LSIF.

The PABX data is stored in a specific ACE: the SACEPBX. Also this ACE works inactive / stand–by pairs. And again, depending on the number of PABXs, you can have

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a number of theses pairs in an exchange. So to retrieve the data of a particular PABX,you have to access the correct SACEPBX pair. The pair is chosen with the PABXidentity. All the data that describes a PABX is stored in the same ACE pair.

The PABX data is retrieved by the PABX Resource Manager (PARM).

– semi permanent data of BCG users

The semi permanent data of BCG users is stored in the SACEBCG. The ACEconfiguration is similar to the previous cases. The correct SACEBCG pair is determinedby the BCG identity.

7.3.2 Dynamic data

a. Definition

Dynamic data is defined as data which only lasts during a call or the time it takes toexecute a facility. This can be from a few seconds to a few minutes.

Here is an example. Remember from the previous chapter that if a subscriber has a callforwarding facility, then the semi permanent data indicates the type of call forwardingand possibly the DN that the call is forwarded to. If a call is made to this subscriber,then the call is clearly forwarded, but temporarily (this means during this call), a counteris kept to count the number of calls that are forwarded simultaneously. This data is thedynamic data.

Dynamic data is created by the service handling software and has to be stored for thetime it takes to execute the service. The data is stored in memory only relations .

The dynamic data is also stored in the SACELSIF, just like the semi permanent data.However the approach for the static (replication over the two SACELSIFs of a pair) cannot be used for the dynamic data. If the dynamic data were replicated over the twoACEs of one pair as well, this would cause a big overhead (the number of updates ondynamic relations is rather high).

The dynamic data is only stored in the active ACE of a SACELSIF pair ! TheSACELSIF pair that is mentioned here is the same pair that also holds the semipermanent data of that subscriber. The correct ACE is again determined by the DNETof the subsciber.

To store and access the data, a separate FMM is designed. This FMM is called theDynamic Data Manager (DDM) . This FMM is a multiprocess FMM. However it is not anormal multiprocess because the tasks are executed by the supervisory process. Theapplications are created to perform time supervision on the services (audit function).

b. Dynamic data users

– Normal users

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For normal users the dynamic data is stored in the SACELSIF as explained in theprevious chapters, and it is handled by the normal DDM.

The data is fully distributed which means that the data is available as long as the CE ison line. The data survives a restart but is cleared after a reload. If the active ACE isdown, the stand–by ACE takes over and becomes the active ACE.

– MSN users

The dynamic data for the MSN users is stored in the same ACEs as for the normalusers and is handled by the normal DDM.

REMARK: if a subscriber uses multiple MSNs then the semi permanent data could bestored in different ACEs because each MSN is connected to a DNET and the DNETcan be different for each MSN. However to make data updates easier (for operatorcommands), the semi permanent data for all the MSNs that belong to the samesubscriber is stored in one ACE. This is the ACE of the default MSN and if a datarequest is sent to another ACE (for the other MSNs) then the DNET of the default MSNis retrieved and the request is forwarded to the default MSN ACE. This ACE alsocontains the dynamic data.

– PBX users

The dynamic data for PBX users is stored in the SACEPBX (active/standby). Unlike thePABX data which is replicated over an active/standby pair, the dynamic data is notreplicated.

Since the dynamic data is only updated in the active CE, it is lost when the standbytakes over (e.g. after a restart). To avoid old (=wrong) data being used, the relationsare updated after a restart.

– Trunks (remote users)

The dynamic data of trunks is stored in the SCALSVT, together with the DDM.

The data survives a restart but is lost after a reload.

c. Overview of dynamic data functions

– Call forwarding

This function stores information on how many simultaneous CFs exist for the sameuser (per basic service). When the maximum is reached, an additional CF will not beallowed and the call is released.

– CCBS & CCNR

This function stores information necessary to set up a call to the busy or no–answeringparty when he becomes free.

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– Queue service

The DDM manipulates the FIFO queue of priority and non–priority waiting calls andensures that the maximum number of queue cells is not exceeded.

– Simultaneous access inhibition for Subscriber Control

The service maintains a ”busy indication” for updating subscriber data, so that only oneprocess can have access at a time. If simultaneous access were allowed, datainconsistency could occur.

– Malicious call identification

The service provides for the intermediate storage of MCI data to give the subscriber theopportunity to request the data output.

– ....

7.4 Triggers to activate supplementary services.

There are different triggers for the activation of a supplementary service. Let us have a lookat the different possibilities.

7.4.1 Trigger from the Originating profile.

The trigger for some services comes from information retrieved from the originating profile.Figure 315 shows a part of the Common Call scenario up to the retrieval of the originatingprofile (message 7). By analysing this profile, CFCS knows that a service has to beexecuted and from this moment on a deviation from the standard scenario can occur.

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Figure 315 : Trigger from the originating profile

Signalling

CFCS

DeviceHandler

Subscriber analysis

1

2 3

4 5

6 71: SETUP or origination message

2: Select Channel

3: Channel Information

4: Activate Call Control

5: Acknowledgement

6: Get Originating Classes

7: Classes Result

Examples :

� Fixed Destination Call : In this case we do not need to collect digits from the originatingsubscriber. The semi permanent data contains the DN to where we have to setup a call.This DN can now be passed to PATED for digit analysis. From here on, we follow thenormal Call Handling scenario.

� Call Completion allowed : If the originating subscriber is allowed to use Call Completion,we have to store all information about this call in the dynamic data (upon request of thesubscriber, see later). This information can be retrieved when the destination subscriberbecomes free.

7.4.2 Trigger from the Prefix Analysis result.

The trigger for a service may also come from the Prefix Analysis result.

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Figure 316 : Trigger from Prefix Analysis

Signalling

CFCS

DeviceHandler

Subscriber analysis

1

2 3

4,9 5,8

6 71: SETUP or origination message

2: Select Channel

3: Channel Information

4: Activate Call Control

5: Acknowledgement

6: Get Classes

7: Classes Result

PrefixAnalysis

10

11

8: Digit Request

9: Digits

10: Prefix Analysis

11: Prefix Analysis result

Example : If a subscriber uses Subscriber Control to change his profile, he dials subscribercontrol codes (*SC*...#) instead of a normal DN. The received digits are sent to PATED forprefix analysis. The PATED result indicates a facility call. From this moment on, the CFCSpasses control to the facility handling software to deal with the service.

7.4.3 Trigger from the terminating profile.

In the case of a terminating call, we pass the DNET value (retrieved by PATED) togetherwith the last three digits to LSIF. Here, we determine the physical location of the calledsubscriber (Terminal Number) and we retrieve the terminating profile. This profile can holdinformation about terminating services (like call forwarding). So this is yet another possibletrigger to leave the standard call flow in order to execute a service.

7.4.4 Recall pulse from the subscriber received.

A Recall pulse is a signal, generated by an analogue subscriber during the stable state ofthe call. It is used to activate a service. Depending on the subscribed services, differentactions can be taken.

Examples

� If a subscriber is subscribed to Malicious Call Identification, the recall pulse is a signal tothe exchange to register the terminating call. As a result, a printout of the call is made.

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� If a subscriber is subscribed to Three Party Service, the recall pulse is used to set up acall to a third party. In the exchange, a receiver is joined to the subscriber and dial tone issent.

The following figure gives a brief overview of the scenario in the case of a recall pulse.

Figure 317 : Recall pulse received

Signalling

CFCS

1

SubscriberIdentification

2 3

4 51: Recall pulse

2: Activate CFCS

3: Acknowledgement

4: Get classes

5: Classes result

Whenever a recall pulse is received in signalling, the Call and Facility Control System will beactivated (actions 1 to 3). Here, the classes of the subscriber are retrieved. (actions 4 and5). Depending on these classes, different actions can be taken. (connect receiver and senddial tone, register the malicious call, book Call Completion, ...)

7.4.5 Trigger from received signalling events (Event monitoring).

a. Definition

The purpose is to have a general, service independent mechanism for SIG for its eventtreatment, so as to avoid that the SIG modules have to do service specific checks tofind out whether an event can be treated autonomously or has to be passed to the callcontrol level. At Call Control level, modules that may be interested in an event include:

– CFCS

– DDM

– PARM

– BCGRM

– Call Control function for intelligent networks.

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When there is interworking between some services (e.g: supplementary service and anIN service), more than one of the above mentioned modules may be interested in anevent.

To cope with all this, a data driven mechanism is created inside SIG.

b. Working principle

Figure 318 shows that there exists a pool of tables. One such table contains eventsreceived by SIG for which the treatment may vary. E.g: a release event can be handledby SIG autonomously , while in some cases another module has to be activated to treatthe event.

Events for which the treatment is fixed are not indicated in the table. E.g: Registerrecall events are always passed to CFCS.

Figure 318 : Event monitoring

Treat Report Link to Send toLocal CFCS CFCS SIG B

Answer Y/N Y/N Y/N Y/NRelease Y/N Y/N Y/N Y/NOn hook Y/N Y/N Y/N Y/N ... Y/N Y/N Y/N Y/N

TACB

.

.

.

POOL

SIG

The meaning of the different options in the table is as follows:

– Treat local

This indication specifies whether ’Signalling Actions’ can be performed by SIGreceiving the event at its side.

– Report to Call Control

Indication whether a call control module has to be informed about the event or not.Signalling will not receive a reply. The module where the event has to be reported to isalso specified.

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– Link to Call Control

Indication whether a call control module has to be activated and linked to SIG. SIG willreceive a reply message containing the process identity of the call control module. Inthis case too, the destination module is specified.

– Send to remote Signalling

Indication whether the event has to be reported to the remote SIG at the other side.

Each TACB is linked to a table, because for a basic call without any service involved,one table is necessary per TACB .

As mentioned before it is possible that multiple destinations have to be informed.Therefore there may be more than one link in the TACB. In case of interworking it issometimes necessary to combine the tables, e.g: perform an ’AND function’ todetermine if local treatment is possible.

Note : Only one link can exist for an unstable call because SIG then reports to the destination whereit is linked to.

Some of the tables (like normal call and specific services) are fixed and only the link tothese tables has to be inserted in the TACB. Other tables are created at CFCS leveland downloaded to SIG (e.g: result of an IN access)

7.4.6 Busy/free changes of a subscriber line (Monitor Access).

a. Definition

The LCE–id of the DDM is stored in the DH. This data is overwritten whenever itbecomes obsolete.

In addition, several call services (e.g: CCBS, CCNR, QS, ...) require a supervisionmechanism based upon the identity of the physical access of a subscriber (LCE–id &TN). This mechanism is used only for lines (analogue or ISDN) and not for trunks.

To cope with all this, a feature ”Monitor ACcess” (MAC) is defined. This is amechanism which uses data stored in the DH.

b. Working principle

Figure 319 shows the working principle.

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Figure 319 : Monitor Access

Request MAC

free

busy

Timer1 Timer2

(1) (2) (3) (4)

free

Report reservation

(1) One or more channels of the access are free but there is no reply (e.g: CCNR) As aconsequence, the service can request to supervise the access .

(2) Access is occupied (e.g: CCBS) Also in this case a service can request to supervisethe access.

(3) When the line becomes free (on hook), the DH is informed (=release). Timer 1 isstarted (e.g: 5s) during which period the subscriber can originate a new call. Anyterminating call is refused.

When the subscriber originates a new call, the timer is stopped, the access becomesbusy again but the MAC request remains booked.

(4) At this moment the MAC requestor is informed. At the same time a timer 2 (e.g:10s) is started during which period the subscriber can start a new call or terminatingcalls are accepted if they are initiated by the MAC requestor (DDM, PARM). Thereforethe call setup must contain a ”MAC indicator” to distinguish this set up from another”normal” setup.

(5) Access free. Any incoming or terminating call is accepted.

The required functionality can be summarized as follows:

– When a subscriber cannot be seized (e.g: busy or no reply) some services maywant to reserve one of the channels and request to report its availability wheneverit becomes free.

– When a subscriber releases the call, he is given some time to originate a new call(timer1)

– After this time out, the requesting facility should be given precedence on this accessfor terminating calls for a limited time (timer2)

– Also the DDM LCE–id is stored in this datastructure.

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c. Interfaces

– Storage of the DDM LCE–id.

The DH stores the LCE of the DDM per subscriber. During the set up of a call, thisinformation is passed to SIG and further to CFCS.

– Request to supervise a subscriber access.

It is possible to check a subscriber access to verify when it becomes free and to passthis information towards the ”monitor access” requestor.

A requestor can be: DDM, PARM, CFCS, BCGRM (=Business Communication GroupResource Manager), ...

Figure 320 gives an example of this principle:

Figure 320 : Monitor Access request

DDM

SIG B

DH

CFCS

ASM B

SCALSV

12

3

1

12

3

3

3

ON HOOK

(1) CFCS received the information that the B subscriber is busy and queueservice is applicable. In this case a request is sent to the DDM which in turnrequests monitor access to the DH via SIG.

(2) The necessary acknowledgements are sent backwards and the CFCSterminates. All the necessary information (dynamic data) is stored and thesubscriber line is in monitoring.

(3) When the subscriber goes on–hook the DH is informed (release). Timer 1 isstarted (see before) to give the B–subscriber the opportunity to start a new call.When the timer expires the DDM is informed, which retrieves the necessaryinformation to start the call. The call setup is started by activating the CFCS.

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For lines belonging to a hunt group PARM is always informed when a line becomesfree. Individual DNs (IDN) can have also timer 1 running (see above). However, GDNscannot have this timer as the access is seized immediately when it becomes free.

7.5 Facility handling examples

7.5.1 Subscriber Control (SC)

a. Facility description.

Subscriber Control allows a subscriber to activate, deactivate, register and invokecertain supplementary services. There are different procedures for analogue and ISDNsubscribers.We will here discuss the case of an analogue subscriber.

Figure 321 : Subscriber Control Procedure

Subscriber Exchange

OFF_HOOK

DialTone

SC–Digits

Confirmation Tone

In case of registration, activation or invocation, the SC – Digits are :

*SC[*PW][*SD]#

In case of cancellation or deactivation, the SC – Digits are :

#SC[*PW][*SD]#

SC: Service Code : Identifies the service to be manipulated.

PW: Password : This is a secret code, assigned on an individual basis. Theassignment, changing and deleting of a password is done by the administration.For some services the use of a password is mandatory.

SD: Service Data : This is a set of parameters, necessary for the manipulation ofthe corresponding service. The layout of this service data is different for eachservice.

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b. Implementation.

The following scenario shows how the subscriber control is handled in the CallHandling. The scenario starts from the moment the prefix digits are received inSignalling. In case that the number of prefix digits is 3, the first digits that will bereceived are : *SC or #SC. These digits are passed to PATED for analysis. The resultfrom PATED indicates that we have a Subscriber Control procedure and from here on adeviation from the general Call Scenario.

Figure 322 : Subscriber Control Scenario

SIG–A

CFCS

DDMPATED

1

2

3

5

6

4 56

SDM

7

8

910

11

LSIF

(1) The received prefix digits from the subscriber (*SC or #SC) are passed to CFCS.

(2) From CFCS, they are passed to PATED for prefix analysis.

(3) PATED analyses the prefix digits and returns as result :

– Type of call = Facility Call

– The type of facility that is being manipulated. This is derived from the analysis of theSC.

– The Facility action (activation, deactivation, invocation, ...) This is derived from theleading * or #.

– The layout of the expected parameters. For each type of facility, PATED can find ina database relation a list of expected parameters, with their layout and an indicationwhether the parameter is optional or mandatory.

All this information is sent back to CFCS. Now CFCS has to perform the followingtasks:

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(4) Pick up the profile of the calling subscriber to check if this subscriber isallowed to invoke Subscriber Control for this service. This is done by sending arequest to LSIF to retrieve the Originating Classes of the subscriber.

(5) Send a request to the Dynamic Data Manager (DDM) to make sure that noother process is updating the profile for this subscriber. At this moment, a busyindication for the CFCS is set, so that from now on CFCS has exclusive access tothe subscriber data.

(6) Perform the combinability check. Again a request is sent to LSIF to collect allnecessary information to check if the service that is being manipulated can becombined with the already active services.

(7) Now the updating of the subscriber’s profile can be initiated. The update itselfis performed by a dedicated FMM, called the Subscriber Data Manager (SDM).Therefore, CFCS sends a command to SDM to start the updates.

(8) First, the SDM will pass its process identity to the DDM. The exclusive accessthat was assigned in DDM (see message 8) is now associated to the SDMprocess.

At this stage the SDM will perform all required Database updates.

(9) At the end of the updates, the exclusive access in DDM has to be released.SDM sends a message to DDM, where the busy indication is reset.

(10) SDM finally sends an acknowledgement to CFCS.

(11) CFCS gives a command to SIG–A to send a confirmation tone to thesubscriber and terminates.

7.5.2 Call Completion to Busy Subscriber (CCBS)

a. Facility Description

This facility allows a calling user A, encountering a busy destination B, to have the callcompleted when the destination B becomes free, without having to make a new callattempt. When user A encounters a busy destination, user A can activate thesupplementary service. The service monitors the destination on becoming free. Whenthe destination becomes free a connection is first set up towards A and when Aanswers, a connection is setup towards B.

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Figure 323 : CCBS Procedure

Subscr. A Exchange Subscr. B

Setup call to B

Check state of B : BusyBusy Tone

Recall

Connect Receiver

Dial Tone

Digits : *SC#

Start monitoring B

Confirmation tone

On_hook

On_hook

Ringing CurrentSet up connection to A

Set up connection to B

Conversation

Ringing CurrentRinging tone

Answer

Answer

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b. Implementation

Figure 324 : A sets up na call to B

SIG–A

CFCS

DDM–A

1

2

3

4

5

SIG–B

DH–B

6

The scenario starts with the setup of the terminating call. LSIF has already found theprofile of the called subscriber and has performed the restriction match.

Remark :

– The profile of the calling subscriber contains a flag indicating that CCBS booking isallowed.

– The profile of the called subscriber contains a flag indicating that CCBS can bebooked against B.

(1) CFCS sends an indication to SIG–A to set up a terminating call towards B.

(2) SIG–A sets up a terminating call towards SIG–B.

(3) SIG–B sends a request to the DH–B to allocate a channel towards B. Now the DHreturns with an indication that subscriber B is busy.

(4) The Busy indication is sent to CFCS.

(5) Since CCBS is allowed (see remark above) and B is busy, the possibility exists thatsubscriber A will book a CCBS. Therefore a request is sent to the DDM–A to store all

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necessary information to handle the booking.

In the DDM, the following information is stored :

– Calling DN

– Called DN

– Terminal Number of A

– Indication that this is an originating CCBS booking.

– Indication that this is only a temporary tuple. The A–subscriber has to activateCCBS booking within a predefined time period. After this period is passed, the tuplewill be removed.

– ...

(6) Now CFCS will send a command to SIG–A to return Busy tone to the callingsubscriber. Then CFCS terminates.

Figure 325 : A books CCBS

SIG–A

CFCS

LSIF

12

3

4

5

SIG–B

DH–B

DDM–BDDM–APATED

6

7

8 9

10

11

12

13

14

15

16

17

This scenario shows what happens if subscriber A books CCBS.

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(1) Subscriber A hits the Recall button. This event is reported to SIG–A

(2) Whenever Recall is received, SIG–A activates CFCS.

(3) CFCS sends a request to LSIF to pickup the profile of the calling subscriber. This isnecessary to check if the subscriber is allowed to use the Recall pulse and to decidewhat to do when recall is received. For CCBS booking, the subscriber must dial theService Code (*SC#). Therefore,

(4) an indication is sent to SIG–A to allocate a receiver and to send dial tone (5) to thecalling subscriber. Also the number of expected digits is passed to SIG–A.

At this point, SIG–A will send a message to ARTA to start the selection of aDTMF–receiver. This action is not shown in the scenario. We continue the scenariowhen the expected number of digits has been received (6).

(7) The received digits are delivered to CFCS.

(8) CFCS sends the digits to PATED for analysis. The result from PATED indicates thatthis is a CCBS booking.

(9) First a request is sent to DDM–A to check if the previously stored information (seefigure 324, (5)) is still stored. It is possible that subscriber A waited too long for thebooking and that the tuple has already been deleted.

(10) Now a request is sent to DDM–B to store also all necessary information on behalfof the called subscriber. This is necessary, because if later B becomes free, the callhas to be set up again from that side.Stored information :

– Calling DN

– Called DN

– Terminal Number of B

– Indication that this is a terminating CCBS booking.

– ...

(11)..(13) DDM–B requests to start monitoring the access of subscriber B.

(14) A confirmation is returned to the CFCS.

(15) CFCS sends a message to DDM–A to indicate that the CCBS is now really active.The tuple at A–side which was marked as temporary, is now changed to active, so itwill not be removed.

(16) CFCS sends a command to SIG–A to send confirmation tone to the A–subscriberand terminates.

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(17) Sending of the confirmation tone.

Figure 326 : B becomes free

SIG–A

CFCS

LSIF

1

2

3

4

5

SIG–B

DH–B

DDM–BDDM–A

6

78

910

11

1213

14

1516

17

DH–A

18

19

20

21 22

23 24

Actions when B ends his previous call and the CCBS is triggered.

(1) On_hook of the B–subscriber.

(2) The RLS event is passed to the device handler. Here, a timer is started, giving Bthe time to originate a new call.

(3) When this timer expires. the DDM–B is informed.

(4) DDM–B reads the CCBS data and activates the CFCS.

(5) In CFCS, first the Dynamic data of the A–subscriber is picked up.

(6) Access to LSIF to get the terminating classes of A. This is necessary because theexchange first sets up a terminating call to the A subscriber.

(7) Command to set up a terminating call to A

(8) Acknowledgement

(9) Allocation of a channel to A.

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(10) Send ringing current to the A subscriber. This is a special ringing current toindicate to A that this is the recall from the exchange.

(11) A answers the call

(12) The answer event is reported to CFCS.

(13), (14) CFCS gives the command to send a special tone to A to indicate that a call toB is going to be set up.

(15) LSIF access to pick up the originating profile of A.

(16) LSIF access to pick up the terminating profile of B.

(17), (18) Terminating Call set up to B

(19) Select a channel to the B–subscriber.

(20) Acknowledgement of the terminating call set up.

(21), (22) CFCS passes the stable call data to SIG–A and SIG–B

(23), (24) CFCS sends a command to DDM–A and DDM–B to remove the dynamicdata for this CCBS. CFCS terminates.

7.5.3 Malicious Call Identification (MCI)

a. Facility Description

This supplementary service enables a user to request that the source of an incomingcall be identified and registered in the network. The following items are registered :

– Time and date of the request.

– Called party number.

– Calling party number (and possibly subaddress).

Depending on the subscription option, the supplementary service may be invokedduring or after the active phase of the call, but in any case before expiration of the MCIinvocation request timer.

b. Implementation

Malicious call identification is a terminating service. Therefore the scenario starts whenthe terminating call is set up.

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Figure 327 : MCI call setup scenario

SIG–A

CFCS

LSIF

12

3

4

5

SIG–B

DH–B

DDM–B

6

7

8

9

10 11

DH–A

(1) Access to LSIF to pick up the profile of the terminating subscriber.

(2) Profile of B is returned. This profile includes an indication that MCI is allowed.

(3), (4) Terminating call setup, via SIG–A to SIG–B

(5) Request to select a channel towards the called subscriber

(6) Set up a connection between called subscriber’s module and calling subscriber’smodule.

(7) Identity of selected channel is returned to SIG–B

(8) Acknowledgement to CFCS

(9) Since MCI is allowed, CFCS sends a request to DDM–B to create a tuple, holdingCalling and Called DN and the current time and date.

(10) CFCS passes stable call data to SIG–A.

(11) CFCS passes stable data to SIG–B. This stable data will hold a monitor table,used by SIG–A to report events to DDM–B and a monitor table, used to activate CFCS.The layout of this monitor table is shown in the next figure.

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Figure 328 : MCI monitor tables

TreatLocal

ReportCFCS

Link toCFCS

Send toSIG–A

AnswerReleaseOn–Hook

InfoRemote answerRemote release

...

Y NNN

NNN

YNN Y

N

Y N Y

N

Y

Y Y YY N N

Y... ... ... ...

TreatLocal

ReportCFCS

Link toCFCS

Send toSIG–A

AnswerRelease

On–HookInfoRemote answerRemote release

...

Y NN

NNNN

Y

N

Y Y

Y

Y YY N

... ... ... ...

YYY

YYY

NN

Monitor table towards CFCS

Monitor table towards DDM–B

According to the Monitor table towards CFCS, SIG–B will start up CFCS whenever :

– Subscriber B releases. In this case the CFCS will send a request to DDM–B toupdate the tuple.

– Subscriber A releases. Here, too, a request is sent to DDM–B to update the tuple.

– Subscriber B sends an INFO message (ISDN only). This is the request from B togenerate a report about this call. Now CFCS will send a request to DDM–B toretrieve the recorded information. Then this information is sent to a dedicated FMMfor subsequent printing.

An analogue subscriber indicates a malicious call by generating a Recall pulse. In thecase of a Recall, SIG–B will always activate CFCS. From this point onwards, theactions are the same as for an ISDN subscriber generating an INFO message.

The monitor table towards DDM–B is used by SIG–B to know which events should bereported to DDM–B for logging. According to the table, SIG–B will inform DDM–B

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about : a local answer, a remote answer, a local release and a remote release. TheDDM–B will update the information.

The following scenario shows what happens if B answers the call.

Figure 329 : MCI, B answers

SIG–A1

2

3

4SIG–B

DH–B

DDM–B

DH–A

(1) B answers

(2) SIG–B sends a request to the device handler to connect the calling and called party.This is the result of the column ”Local Treatment” in both monitor tables. This columnindicates two times YES.

(3) Send a report to DDM–B. This is the result of the second monitor table (towardsDDM–B). Here the column ”Report CFCS” states YES. No reply is expected.

(4) Send the answer event to the SIG–A. This is the result of the columns ”Send toSIG–A” of both monitor tables. Both columns have the indication YES.

The following scenario shows the actions when a Recall is received. This is the case ofan analogue subscriber. For the ISDN subscriber, this corresponds to the reception ofan INFO message.

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Figure 330 : MCI, Recall from B received

SIG–A

CFCS

LSIF

1

2

4

SIG–B

DDM–B

3

AlarmCall

FMM

5

(1) Recall event received.

(2) Whenever a Recall is received, CFCS is activated. When activated, CFCS returnsits process id to SIG–B.

(3) CFCS accesses LSIF to retrieve the profile of the B–subscriber. This is necessarybecause we have to check if no other services requiring a Recall, are active. In thatcase, we will have to connect a receiver and send dial tone to B. Then B can pass theService Code, corresponding to ”MCI request”.We consider the case where no other services are active. This implies that the Recallmust be an MCI request. So no receiver will be connected.

(4) Request to DDM–B to retrieve the information from dynamic data and to delete theallocated tuple. The data is passed back to CFCS.

(5) CFCS sends the data to a dedicated FMM where the necessary actions are taken toprint out the report. These actions are not shown in the scenario.

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8. CHARGING

8.1 Charging functions

Figure 331 : Charging functions

Ç

charginganalysis

charginggeneration

chargingcollection

charging

NSCcall

handling

BILL

billingcentre

chg acc

S S

S

S2 S

chg = chargingacc = accounting

output

taxation

N7 X25

X25

centre

The different functions of charging:

� charging analysis;

� charging generation;

� charging collection;

� charging output;

� accounting.

These components can be situated in the same exchange as the call handling, but each ofthem individually can be located in a different node. As an example consider a situationwhere the charging generation is done in the own exchange, whereas the charging analysisis performed in an other exchange.

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Figure 332 : Charging analysis in an other exchange

charging generation

charging analysis

A–party DNB–party DN

tariff code

other exchangeown exchange

The other exchange can be a higher–order exchange, a transit exchange or any other typeof exchange. The own exchange supplies the other exchange with the A–party DN and theB–party DN. The other exchange then checks which tariff is applicable to this call.

To allow charging generation in the own exchange, the information about the tariff, in theform of a tariff code, is returned to the local exchange. The tariff code is translated in thelocal exchange into a tariff group and a tariff identity (see chapter 8.4.2).

8.2 Different ways to charge calls...

8.2.1 Bulk billing

During the conversation a counter is incremented. After the call the counter value is addedto the subscriber’s bulk counter.

8.2.2 Detailed billing

Every call is charged in such a way that a detailed billing record is provided at the end of thecall. The contents of this record is very administration dependent, but it may containamongst others:

� the A–party number;

� the B–party number;

� the start and end time of the call;

� the amount of pulses accumulated during the call;

� certain facilities that were triggered during the call.

8.2.3 Detailed billing observation

Detailed billing observation is similar to detailed billing. The difference is that detailed billingobservation is a facility that is assigned to a subscriber, for example if he complains about

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his bills. The purpose of detailed billing observation is only to obtain a detailed record of thecall. The standard charging is still applicable as well to charge the call.

8.2.4 Toll ticketing

Toll ticketing should be considered as a combination of detailed billing and bulk billing : onlyfor calls to specific directions the detailed billing will be used, while for other directions thebulk billing method should be used.

8.2.5 Automatic Message Accounting (AMA)

AMA is an other name for any type of detailed billing.

8.2.6 Division of revenue (accounting)

The purpose of Division Of Revenue is to split the collected revenues between differentadministrations, in case more than one administration is envolved for setting up callsbetween two subscribers. The reason why the DOR function exists, is the fact that thecalling subscriber will only receive a bill from the administration he is connected to, while therevenue for that call should be divided over the two administrations.

In order to know how much of the money collected by the administration should be paid tothe other administration, the S12 keeps track of :

– the number of calls

– the number of pulses

– the total conversation time

– the amount of seizures

– the amount of seizure seconds

as a function of the destination and time.

8.2.7 Charging statistics

The purpose of the charging statistics is to investigate on which calls the most money isearned. Its implementation is based on the DOR implementation, whereby some extraaccounting classes are defined to which only the number of calls and the number of pulsesare associated.

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8.2.8 Limit of credit

Limit of credit is assigned to a separate counter per subscriber. When this counter reachesa certain limit of tariff pulses within a predefined time limit, some types of outgoing calls willbe barred.

8.2.9 Advice of charge (AOC)

Advice of charge is a facility of an ISDN–subscriber, allowing him to receive charginginformation on an individual call basis (requested at seizure), or permanently for all calls thesubscriber makes.The charging information is sent to his telephone set or to the PC connected to his basicaccess.Three variants of this facility are defined :

– AOC at call set–up;

– AOC during the call;

– AOC at the end of the call.

8.2.10 Facility charging

Whenever a subscriber activates, deactivates, invokes or interrogates a facility, he may becharged for it. The charging type in this case is facility charging.

8.3 Charging methods

8.3.1 Unit charging

Unit charging is understood as a charging method whereby a number of pulses is definedper time interval. Each of these pulses represents a certain cost, which is the same for allpulses charged during the call. Pulses are charged to the subscriber at the beginning ofevery time interval, or at the end of every time interval, depending on the charging method.

a. Unit Fee

The charging counter associated with the call is incremented only once with a certainnumber of pulses at the moment charging needs to be started, e.g. upon answer of thecalled subscriber.

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b. Periodic metering

The charging counter is incremented periodically with a number of pulses after eachelapsed time interval. The time interval between two increments is called the rate .Different methods use a different starting point for the periodic pulses.

Figure 333 : Unit Charging Methods

Unit Fee

Periodic

a

b b b b

rate

b

start of charging end of charging

a: unit fee pulsesb: periodic pulses

b

8.3.2 Continuous charging

Continuous charging is understood as a charging method whereby a price is determined pertime interval. If the length of the call is not a multiple of this time interval, the price iscalculated, up to a certain granularity, taking into account the exact call duration.

Total cost = call set–up cost + SUM taken over all tariff periods (price per time unit * callduration)

E.g. : price = 500 centimes per 6 min call duration = 230 sec call set up price = 300 centimes granularity = 1 sec

cost of the call = 300 + ( (500/(6*60)) * 230) = 619 centimes (see figure 334).

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Figure 334 : Continuous charging

500

1000

1500

360 720 1080

.

unit

continuous

call set–upprice

COST

TIME

(centimes)

(seconds)

619

230

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8.4 Charging analysis

8.4.1 Charging analysis with MMC commands

Figure 335 : Charging analysis with MMC commands

DAYCAT

DISPLAYTARIFF

ZONE

CHARGING

WEEKCAL

SCALE

DESTCH

ORCHG

DATE

holiday

not holiday

TIME

RATESEQ

RATE

CALENDAR:HOCAL

DISPLAY

CHARGINGCALENDAR:

DISPLAYDAY OFWEEK

DISPLAYCHARGING

DISPLAY DISPLAY

CHARGING CHARGINGTARIFF

DAYCAT

modulators

charging details

charging tariff

DISPLAYTARIFF

MODULAT

TZ

TG = tariff groupTI = tariff identity

TZ = tariff zone

TG’

modulators

TG/TI TG’/TI’

This overview is used in the following chapter to explain the different charging parameters.

8.4.2 Charging parameters

a. origin for charging

Each subscriber line or incoming trunk connected to the exchange is, for chargingpurposes, identified by an origination code. This code has been created to group thegeographical origins that are considered by the charging system as unique origins. Thiscode is called the origin for charging, abbreviated to ORCHG in figure 335. It is derivedfrom the source code which in turn defines the originator of the call (subscriber group,incoming trunkgroup).

E.g. see figure 336: subscriber 1 (belonging to an RSU) and subscriber 2 areconnected to the same exchange. Because they have a different origin for charging,they can be charged at a different rate for the same destination.

b. destination for charging

This parameter is used to group destinations that are considered by the chargingsystem as unique destinations. This code is derived from the dialled prefix. Refer toDESTCH in figure 335.

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c. tariff zone

The tariff zone defines a measure of distance between the charging origin and thecharging destination. Refer to figure 336: if a subscriber with origin for charging Amakes a call with destination for charging 1, then the tariff zone is A1. If an othersubscriber, with origin for charging B, makes the same call, with the same destinationfor charging 1, then the tariff zone is B1.

Figure 336 : Charging Overview

Exch 1 Exch 2RSU

Subscr 1

AREA 1

Exch 3

AREA 2

dest chg 1

dest chg 2

orig chg B

Subscr 2

orig chg A

tariff zone A1

tariff zone B1

tariff zone A2

dest chg 1

dest chg 2

tariff zone B2

The following MMC command demonstrates how the destination for charging that wasobtained from prefix analysis (DESTCH = 2), is translated in a tariff zone, depending onthe origin for charging (ORGCH 0 – 3 give TARZONE 3, ORGCH 4 gives TARZONE 4).

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ÊÊDISPLAY–TARIFF–ZONE:DESTCH=2.

DISPLAY–TARIFF–ZONE SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

TARIFF ZONE

ORGCH ORGUSE DESTCH UNIQUE TARZONE BCGTARZONE

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

0 IN USE 2 NUNI 3 NO




d. modulators

Modulators are extra parameters that may influence the final result of the charginganalysis. Modulators can operate on two levels:

– charging modulators can change the charging task that was found in a completelynew charging task;

– tariff modulators can only change the tariff group and tariff identity that were foundto new values.

The following parameters can be used as modulators:

– type of call;

This parameter defines the calling party category (CPC) , eg. normal subscriber,priority subscriber, coinbox, and so on. This code is retrieved from the class ofservice.

– bearer capability;

For ISDN–calls the charging may also depend on the bearer capability requestedfor the call. This parameter is received from the calling ISDN subscriber in theSETUP message. It allows the administration to charge a subscriber in relation tothe minimum quality of the connection requested by the subscriber.

– high layer compatibility;

– tariff type indicator (TTI), used in IN;

– BCG indication;

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– analogue/ISDN indication.

Note : A parameter can be used as either a charging modulator, or a tariff modulator.

The tariff modulators can be displayed with a specific MMC command:

ÊÊDISPLAY–TARIFF–MODULAT:TARGRPID=1&1,TYPE=INT.

DISPLAY–TARIFF–MODULAT SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

TARIFF MODULATOR

TYPE : INT

TARGRPID : 1 & 1

MOD1 = BCG MOD2 = HLC MOD3 = FAXSTR MOD4 = ANALISDN

MOD5 = IIBERCOM MOD6 = FULLHALF

MOD1 MOD2 MOD3 MOD4 MOD5 MOD6 TARMOD

GRP ID

–––––– –––––– –––––– –––––– –––––– –––––– –––––––

0 1 FALSE ANLOG FALSE HALF 2 1

0 0 FALSE ANLOG FALSE HALF 34 1

e. charging details (or charging task)

The above mentioned parameters define a unique charging task. This task includes:

– charging pattern: when to start and stop the charging;

– charging type: bulk billing, toll ticketing;

– charging analysis point: own exchange, higher order exchange;

– charging generation point: own exchange, not own exchange;

– recording point for bulk billing: own exchange, not own exchange;

– class of meter: to which subscriber’s meter are the pulses added;

– tariff group and tariff identity : they indicate which charging method, rate, number ofpulses will be used.

An example is given with the following MMC command and the resulting output. Fromthe prefix analysis we received a destination for charging (= 5) and an origin forcharging (=0), which is used as input in the operator command.

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ÊÊDISPLAY–CHARGING:TARZONE=3

DISPLAY–CHARGING SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

TARZONE

=======

3

TARIFF TARIFF CHPAT

ANALP RECPFBK GP & ID CLASS START STOP LNGCOMSI

===== ======= ======= ====== ================== ========

CHOWN SCP 1 5 5 CHSUBASW ANNMSTOP 0

RECIND CHANRES

KIND COMB PARTY TYPTRAF CHSEL INC OUTG CHGENPT

=================== ======= ====== ================= =======

NOIND COSPR CG INT SINGLE CHINCNON CHOGNONE CHOWN

LINEMTR

TOTCHSTA CHSTAALW NOAOCH NOPLSTAR 1 2 RSEQSND

======== ======== ====== ======== ======== =======

0 FALSE FALSE FALSE 0 0 FALSE

AMADCR

========

DBLNG

The output gives us tariff group 1 and tariff identity 5. We also find that charging has tostart at answer and stop at an announcement.

f. Tariff group

In every exchange, we can define 8 calendar types, consisting of a week calendar anda holiday calendar. This calendar type will give each day a day category : a workday, aweek–end day, a holiday and a special day.

The function of the calendar type is to allow administrations to charge international callsaccording the local calendar of the destination. Since in the USA Saturday isconsidered to be a workday, a call to the USA on a Saturday will be charged against anormal tariff, and on a Sunday against a reduced tariff. A call on a Saturday to aNordic country, however, will be charged against a reduced tariff.

To determine the day category, first the holiday calendar has to be checked:

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ÊÊDISPLAY–CHARGING–CALENDAR:HOCAL,YEAR=1996.

DISPLAY–CHARGING–CALENDAR SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

OPTION = BASIC HOLIDAY CALENDAR

––––––––

CALENTYP – YEAR – MONTH – DAY –––> DAYCAT DAY OF WEEK

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––

1 – 1996 – JAN – 1 HOLIDAY MO

1 – 1996 – APR – 8 HOLIDAY MO

1 – 1996 – MAY – 1 HOLIDAY WE

1 – 1996 – MAY – 16 HOLIDAY TH

1 – 1996 – MAY – 27 HOLIDAY MO

1 – 1996 – JUL – 21 HOLIDAY SU

1 – 1996 – AUG – 15 HOLIDAY TH

1 – 1996 – NOV – 1 HOLIDAY FR

1 – 1996 – NOV – 11 HOLIDAY MO

1 – 1996 – DEC – 25 HOLIDAY WE

If a particular date is not a holiday, then the week calendar has to be checked with theweekday.

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ÊÊDISPLAY–CHARGING–CALENDAR:WEEKCAL.

DISPLAY–CHARGING–CALENDAR SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

OPTION = BASIC WEEK CALENDAR

––––––––

CALENTYP SU MO TU WE TH FR SA TABLE

––––––––––––––––––––––––––––––––––––––––––––––––––––––––

1 WKA WDA WDA WDA WDA WDA WKA ACTIVE

2 WKA WDA WDA WDA WDA WDA WDA ACTIVE

3 WDA WDA WDA WDA WDA WDA WDA ACTIVE






1 WKB WDB WDB WDB WDB WDB WKB PASSIVE

2 WKB WDB WDB WDB WDB WDB WDB PASSIVE

3 WDB WDB WDB WDB WDB WDB WDB PASSIVE





8 WDA WDA WDA WDA WDA WDA WDA PASSIVE

A tariff group corresponds with one calendar type and one charging scale. A chargingscale specifies for each day category (workday, holiday, week–end, ...) and for eachswitch–over time in that day category, the corresponding rate sequence number(normal, reduced) to be used. This is shown in the next example :

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ÊÊDISPLAY–CHARGING–SCALE:TARGRP=1.

DISPLAY–CHARGING–SCALE SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

OPTION = BASIC SCALE

TABLE = BOTH TABLE WITH A ACTIVE

ACTIVE TABLE

SCALE

GROUP CALENTYP DAYCAT HOUR : MIN RATESEQ

–––––––––––––––––––––––––––––––––––––––––––––––––

1 1 WD A 0: 0 RATESEQ1A







1 1 WK A 0: 0 RATESEQ4A

1 1 HO A 0: 0 RATESEQ4A

1 1 SP A 0: 0 RATESEQ5A

PASSIVE TABLE

SCALE

GROUP CALENTYP DAYCAT HOUR : MIN RATESEQ

–––––––––––––––––––––––––––––––––––––––––––––––––

1 1 WD B 0: 0 RATESEQ1B







1 1 WK B 0: 0 RATESEQ4B

1 1 HO B 0: 0 RATESEQ4B

1 1 SP B 0: 0 RATESEQ5B

On workdays the following rate sequences apply:

– from midnight till 8 Hr: rate sequence 1A

– from 8 Hr till 9 Hr: rate sequence 2A

– from 9 Hr till 12 Hr: rate sequence 3A

– from 12 Hr till 13.30 Hr: rate sequence 2A

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– from 13.30 Hr till 17 Hr: rate sequence 3A

– from 17 Hr till 18.30 Hr: rate sequence 2A

– from 18.30 Hr till midnight: rate sequence 1A.

You also find the rate sequences for week–end days, holidays and special days.

Note : Although the parameter “rate sequence” usually only takes the values ”rates1”and ”rates2”(normal and reduced), other values may be applied. If the administration decides to employ a specialtariff for calls made during the busy hour, then the parameter rate sequence can be assigned thevalue ”rates3”. This new rate sequence will result in a different charging method, different pulses,different period.

Note : In the database some data is stored in an active table and in a passive table . This allowsthe operator to first implement new data changes in the passive tariff plan. After having checked allhis inputs, he can then switch over from passive to active table via an operator command.

g. Tariff identity

A tariff identity defines the content of the different rate sequences. There may bedifferent tariff identities for the same charging scale (= same tariff group).

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ÊÊDISPLAY–CHARGING–TARIFF:TARGRPID=1&2,TABLE=ACTIVE.

DISPLAY–CHARGING–TARIFF SUCCESSFUL

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

TABLE : ACTIVE TABLE A

TARGRPID : 1 & 2

TARCLS : 2

TARKIND : FIX

TARCLSGP : 0

BCGIND : OFF

SUBTKDTO : OFF

MINTIME LINEMTR

RATESEQ : CHMETH RATE RATETYPE CHGTYPE TAX NRC

––––––– –––––––––––––––––––––––––––––––––––––––––––––––

RATESEQ1 : UNFSYN 0 DECISEC CHSTRMEX 15 15

PHASE TIMES PULSES RATE RATETYPE NEXTPHASE

––––––––––––––––––––––––––––––––––––––––––––––––––––––

0 1 1 3600 DECISEC 1

1 ENDCALL 1 3600 DECISEC 1

MINTIME LINEMTR


––––––– –––––––––––––––––––––––––––––––––––––––––––––––



––––––––––––––––––––––––––––––––––––––––––––––––––––––

0 1 1 1800 DECISEC 1


MINTIME LINEMTR


––––––– –––––––––––––––––––––––––––––––––––––––––––––––



––––––––––––––––––––––––––––––––––––––––––––––––––––––

0 1 1 1500 DECISEC 1


The examples show that for tariff group 1 and tariff identity 2 the charging method isunit fee synchronised, with one unit fee pulse and one periodic pulse. The period is:

– 3600 deciseconds (=360 seconds = 6 minutes) for rate sequence 1 and 4;

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– 1800 deciseconds (=180 seconds = 3 minutes) for rate sequence 2;

– 1500 deciseconds (=150 seconds = 2.5 minutes) for rate sequence 3.

The tariff identity thus specifies which rate will be used at a specific time.

A tariff group covers tariff identities for which the same charging scale and calendartype are used.

Up to 64 tariff groups each comprising maximum 32 tariff identities are allowed.

8.4.3 Software involved with charging analysis

This paragraph describes a general call charging scenario. The charged call can be one ofthe following : an analogue subscriber, an ISDN subscriber, a trunk call. Depending on thecase, the charging is handled in different modules : ASM, ISM, DTM, ITM, SCM.

Depending on the requirements of the administration, charging of an analogue call will beactivated :

– when the calling subscriber goes off–hook;

– after indialling the prefix;

– after indialling the complete number.

For an ISDN call there is no indialling because all the digits are received at once.Nevertheless the moment of activation can also be after prefix analysis, ...

Figure 337 gives an overview of the software actions on activation of the chargingsubsystem.

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Figure 337 : Activation of charging

CFCS CGC

LCG

CHAN

SCALSV

TCE

1 2

36

MCCASSM

TCASSSM

4 5

[ 1 ]Request from CFCS sent to Charge Generation Control (CGC) to activate the chargingtogether with the parameters charging needs (origin for charging, destination for charging,type of call, bearer capability ..). CGC allocates a temporary buffer in which all charginginformation for this call is stored.

[ 2 ]CGC needs the following information:

– charging method;

– rate;

– number of pulses (unit fee and periodic);

– facilities;

– division of revenue;

– detailed billing.

To receive it, CGC sends a message to Charging Analysis (CHAN) with the necessaryparameters retrieved from CFCS.

[ 3 ]CHAN completes the charging analysis and sends the data back to CGC in one or moremessages. CGC copies this data to the already seized buffer.

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[ 4 ]CGC translates the taxation directory number received from CFCS into a so called chargingkey. This key determines in a unique way the location where the subscriber meter is stored.This function is performed by the Meter Counts Collection Access (MCCA) SSM.CGC passes all this information to the Local Charge generation FMM, situated at TCE level.Then CGC releases its own buffer. LCG in turn allocates one or more taxation cells (e.g. incase of facilities). The cells that belong to the same call are linked together.

The cells contain the charging data from CHAN, a counter to add the pulses and space tostore the time stamps needed for detailed billing.

Note : In case both the A–party and the B–party have to be charged (for example for a split chargingfacility call), then CGC sends a message to both the TCE of the A–party and the TCE of the B–party.

[ 5 ]Finally LCG sends a report message to CGC. This message contains the taxation cellidentity and the task that CGC has to perform. The task here is to inform CFCS. Now LCGwaits for the start charging event.

[ 6 ]CGC sends the acknowledgement to CFCS.

8.5 Charging generation

Figure 338 : Charging generation

TCE

eventsMetering

SSM

TCASSSM

AOCSSM

1

2

LCGSIG

[ 1 ]Each call event detected by Signalling (SIG) is reported to the LCG FMM (e.g. answer, clearback, clear forward, forced release...). These events are compared with the start and stopcharging events.

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In case of the start charging event (e.g. at answer), the charging meter in the taxation cell isstepped up depending on the charging method used. For periodic charging a timer isstarted.

In case of the stop charging event (e.g. clear forward), LCG stops accumulating thesubscriber meter and cancels the periodic time–out.

LCG uses three SSMs:

� Metering SSM: this SSM increments at the correct time the subscriber’s counter in the taxcell;

� Advice Of Charge (AOC) SSM: this SSM calculates the charging amount the subscriberhas to pay up to now and informs signalling at the time that was requested by thesubscriber [ 2 ] . Signalling sends the AOC information to the subscriber’s ISDN set.

� Taxation cell access SSM (TCAS): access to the taxation cell is performed via a commoninterface: the TCAS SSM. This SSM is also present in the SACE, because some of theLCG functions are now handled in the SACE.

8.6 Charge scale change–over

This function allows to change from one set of charging parameters (charging method,number of pulses, periodic rate ...) to another one as a function of the day of the year andthe time of day.This function is handled by an FMM situated in an Active/standby pair ACE, called ChargeScale Change Over FMM (CSCO). Via database relations, the FMM knows for each tariffgroup the current and the next rate sequence (normal, reduced..) to be used. It informs (seefigure 339):

– all CHAN FMMs to ensure that all new calls apply this new rate sequence.

– all LCG FMMs to ensure that all calls in conversation are switched over to the newtariff corresponding to this rate sequence.

– maintenance to set/reset the day/night indicator on the master alarm panel (MAP), ifrequired by the customer.

At switch–over time, CHAN is informed of the current and new rate sequence number foreach tariff group via the normal message routing principle.

This principle is not used to update all the LCGs in the line and trunk modules because thiswould take too much time. Instead the broadcast principle is used. The messages are sentto an FMM in the CTM modules where they are inserted in the tone link in a specific channeland thus sent to all the TERIs port 5.

So, at switch–over time, all LCGs receive via the broadcast mechanism all data they needfor both well the current and the next switch–over time (rate sequence number, tariff group

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and identity, tariff method, number of pulses ...). This data is stored in the LCG.The LCG then starts a time–out for the next switch–over time. When this timer runs out,LCG already has the charging data applicable at that moment from the previous broadcastmessage of CSCO. If there are cells with a difference between the current charging and thenew one, a switch–over action is done.

Figure 339 : Charge scale change–over

CHARGESCALECHANGEOVER

MAINTENANCESW

BROADCASTSW

OPERATINGSYSTEM

CHARGEANALYSIS

Switch ON/OFF

DAY/NIGHT tariff

Trigger LCGSwitch–over

New Tariff Info

:::

Switch over to next tariff

LOCAL CHARGEGENERATION

MASTER ALARMPANEL

SYSTEM 12

NextRate

ActualRate

ActualRate

NextRate

:::

8.7 Charging collection

In this chapter different possibilities are shown for handling the charging results after a call.The results can be stored locally in the exchange on disk or sent directly to a taxation centrevia a N7 link. Another possibility is immediate billing to an external device : e.g. to a printerin a hotel.

8.7.1 Bulk billing collection

The collector FMM for bulk billing is the Meter Counts Collection (MCC) FMM . MCC isstored in the SACECHRG, an active/stand–by ACE. There can be a number of ACE pairs in

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an exchange (minimum two) according to the size of the exchange (number of equippedsubscribers) and administration requirements.

The bulk billing data is sent to the MCC on a per call basis. The bulk billing data is senteither at the end of the call or at some intermediate points during the call, reachingthresholds of pulses and/or chargeable duration in time.

To secure the transport between the TCE where the charging data is generated and thecentralised collection function, a sequence numbering is used.

The collection function will then accept messages carrying these sequence numbers in awindow, allowing it to detect missing and retransmitted messages.

The sending of bulk billing data towards MMC is shown in figure 340.

Figure 340 : Scenario bulk billing collection

Local ChargeGeneration

Meter CountsCollection

(stand–by)

(active)

1 2

3

4

tax cell

checksumcharging keycounters

Meter CountsCollection

checksumcharging keycounters

TCE

SACECHRG

SACECHRG

LCG sends the charging data to the active MCC. The active MCC forwards the data to thestand–by MCC. The stand–by MCC finally sends an acknowledgement to LCG.

Periodically all the counters are stored on disk (always duplicated ). The time interval is aCDE parameter. The transfer from memory to disk is done in blocks of 2K Bytes.

8.7.2 Detailed billing collection

The detailed billing records can be handled in two ways, depending on whether local storageor central storage is used:

� local storage

The records are kept in a buffer and stored on a disk file when this buffer is full .

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� central storage

The detailed billing records are stored in a temporary buffer and sent on–line to aremote taxation centre for further processing.

a. local storage of detailed billing records

There are a number of ways to sort the detailed billing records:

– sorting per day

Records are written in 31 files, depending on the day of the month. Only recordsthat satisfy the selection criteria are written to disk.

– sorting of charging observation

This function is called time period detailed billing observation (TPDBO). Thepurpose is to record all calls generated by specified subscribers, meeting certaincriteria. The selection criteria determines to which files selected records arewritten. An example is to store the records per subscriber.

– chronological sequential output

Here a file, or a group of files are used per charging record type. The records arewritten to disk in the same order as they appear.

Figure 341 sketches the chronological collection.

Figure 341 : Chronological collection

CHRONO

LCG

TL SSM

TXCS

1

2

3 4 5

master slave

CHRONO TXCS

6

TCE

SACECHRG SACECHRG

TDFM TDFM

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The following software is involved:

– Chronological collector (CHRONO) FMM:

The CHRONO FMM receives the charging records from LCG. CHRONO thenchecks the sequence and the checksum.

– Taxation Collector (TXCS) SSM:

The SSM is responsible for the memory storage of the records, the interface withthe mate processor and the determination of the master / slave state.

– Tax layouter (TL) SSM:

This SSM performs the layouting of the charging records.

– Taxation Disk File Manager (TDFM) FMM:

TDFM handles the interface with the input/output system. It also selects a file or afile group. TDFM transfers the records to disk when either the relation where therecords are stored in memory, is full, or when a timer expires.

b. central storage of detailed billing records

After generating and collecting the detailed billing records of a subscriber, the recordscan be transferred to a centralised point in real time. This point is called a taxationcentre. A taxation centre can be a stand–alone system, or it can be collocated in anexchange.

The detailed billing records are stored on disk or tape for later transfer to a billingcentre. Here finally the records are processed, resulting in the bills that are presentedto the subscribers.

There are two FMMs for the specific central storage actions:

– Taxation Collector (TAXCOL) FMM;

– Originating Taxation User Part (OTAXUP) FMM.

The beginning of the central storage is identical to the local storage. Please refer tofigure 341. Then the following happens:

– TXCS triggers the TAXCOL FMM when the relation where the records are stored, isfull, or when a timer expires. TAXCOL then stores the records in a taxation buffer.

– at fixed intervals OTAXUP checks whether the taxation buffer is full. If the buffer isfull, the records are sent to the Destination Taxation User Part (DTAXUP) in thetaxation centre via the N7 network. When TAXUP receives an acknowledgementfrom DTAXUP, it deletes the records from the taxation buffer.

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For security reasons OTAXUP can send the records to two taxation centres: the normalor the alternate taxation centre.

8.7.3 Division of revenue collection

a. Accounting principle

Division of revenue (DOR) is used when the fee for a certain outgoing call has to bedivided between different administrations. This is done by gathering the number ofpulses, call duration, number of calls, seizure duration and number of seizures incounters as a function of the destination and time period.

DOR makes no reference to individual calls or to the individual subscribers. The pulsesare accumulated in counters defined by an accounting class.

For the purpose of DOR between administrations, 6000 accounting classes areprovided.

Each accounting class provides 5 counters :

– number of conversation minutes (time between answer and release)

– number of pulses

– number of calls

– number of seizure seconds (time between seizure and release)

– number of seizures.

b. Method of Collecting Division of Revenue

The Division of Revenue Collection is distributed over:

– CHRONO and TXCS;

– an Intermediate Division of Revenue Collector (IDRC) in the SACECHRG;

– several Division of Revenue Collectors (DORC) in SACECHRGs.

After a call, where DOR is required, the following happens (see figure 342):

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Figure 342 : Division of revenue collection

checksumaccounting classnumber of seizuresseizure durationnumber of callscall durationnumber of pulses

...

DORC

LCG

(active)

checksumaccounting classnumber of seizuresseizure durationnumber of callscall durationnumber of pulses

...

DORC

(stand–by)

IDRC

TCE

1

4

5

7

Buffer

TXCS

CHRONO2

3

6 SACECHRG

SACECHRG

[ 1 ]At the end of the call, LCG sends the charging cell to CHRONO in a loadsharing way.

[ 2 ]CHRONO stores the information in temporary buffers.

[ 3 ]When a buffer is full, TXCS informs IDRC.

[ 4 ]IDRC finds out which DORC is used for a specific accounting class.

[ 5 ]DORC passes the updated information to it’s mate.

[ 6 ]The stand–by DORC sends an acknowledgement to the IDRC, which can release thecell.

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[ 7 ]At regular intervals all counters are stored to disk. To save the counters on disk twoalternatives are provided:

– read before write;

– write only.

8.8 Charging output

The collected charging results can be treated in different, customer dependent ways :

� transfer data to magnetic tape, optical disk or system printer.

� transfer charging data to a Network Service Centre (NSC).

� transfer charging data via an X25 link to a billing centre.

The master program of all charging output activities is the Charge Recording Manager(CRM). All charging requests, both manual and automatic, are passed via the CRM to thedifferent FMMs depending on the charging data type.

The activation of the charging output can be done :

� manually via an operator command in the exchange;

� automatically as populated in database;

� requested by TDFM when a file is full;

� requested by the NSC : scheduled or via an operator command;

� requested by the billing centre.

8.8.1 Bulk billing output

The bulk billing data was collected at ACE level by the MCC FMM . This data is furtherprocessed for output by the Output Meter Block (OMB) FMM . OMB performs theformatting required by the administration. Here, 2 possibilities exist :

� transfer the formatted data to magnetic tape, optical disk or system printer.

� transfer the formatted data to a disk file. Disk files can be used as an intermediatestorage for formatted files , before this information is sent to the Network Service Centre.

The CRM is the controller for the OMB. All requests are routed through and verified by theCRM. A request originating in the NSC is passed to the CRM via the Exchange OMUP

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(Operations and Maintenance User Part) Subuser(EOS). Local operator commands arerouted via Man machine to the CRM.

The function of the OMB is: (see also figure 343):

� fetch the unformatted data

OMB sends a request to the active MCC FMM(s). Receiving data from the MCC givesus the possibility of getting recent data taken from memory or data already stored ondisk (chosen via a flag in database). The data is sent in blocks of 2 kB to the OMB.

� format the data

OMB sorts the meters per DN and omits the non–equipped DNs. The data is formattedinto codes required by the administration (ASCII, EBCDIC, BCD) and by the outputdevice (tape,disk, printer, binary devices). This is completely data driven.

� transfer the data to a specified output device

Via the Input/Output SW, OMB requests a file on disk or tape (or optical disk) to copythe formatted data or it sends the data to a printer or binary device.

Figure 343 : Output of bulk billingTO/FROM NSC

I/O SOFTWARE

I/O SOFTWARE

Tape or ODBUFFER

unformatted data

METER COUNTS COLLECTION

OUTPUT METERBLOCK

Output to NSC via EOS

EXCHANGE OMUPSUBUSER

CHARGERECORDINGMANAGER

operatorrequest

unformatteddata

formatteddata

8.8.2 Detailed billing output

Via the TDFM the AMA records were written on twin disk files. When a big amount ofdetailed billing records are generated in an exchange, one collector or one disk pair may not

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satisfy. In that case several collectors (TDFM) and disk pairs may exist. So besides thePLCE module, one or more Peripheral and Backup Database CE (PBDCE) pairs can beequipped.

An interface is required between the CRM and the collectors (TDFMs): the CollectorController (COLC) . This FMM determines which input file of which collector needs to beformatted next for output. The COLC FMM is a multi–process FMM because it must handlerequests for different AMA call types, different disks and different collectors at the sametime. It is located in the same ACE as the CRM: the SACE Command handler and Output(SACECP).

a. Detailed billing output to tape, optical disk or NSC

All output requests, whether they are automatic requests because of a threshold that isreached, or whether the request is triggered by an operator or by an NSC, are passedto the CRM. The input for CRM is an unformatted file. CRM then formats the file into asuitable layout for tape. The output file is called the formatted file. Via database theCRM defines the identity of the output file.

In case of transfer to an NSC, the requestor of the dump is always the NSC. The outputfile is formatted and transferred to an intermediate disk file, waiting to be copied by theNSC.

For the output of the AMA files, we need two FMMs:

– the AMA File Formatter (AFF) FMM;

The AFF formats and transfers the files. The formatting is completely data–driven.The AFF FMMs are distributed over all CEs that contain output devices. Thisincludes the P&L and the PBDCE.

– the AMA File Formatter Controller (AFFC) FMM.

The AFFC controls the AFFs. The AFFC is located in the same active/stand–byACE as the CRM and the COLC: the SACECP.

The CRM passes the request to dump the file(s) to the AFFC. The AFFC needsinformation about the input files, like the file identity, the start read pointer, the end readpointer. This information is retrieved by the Taxation Disk File Manager (TDFM) FMM,via COLC. The information is then passed to the involved AFFs.

The FMMs involved and a scenario are shown in figure 344.

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Figure 344 : Detailed billing output to tape, optical disk or NSC

stand–by SACECP

AFF SSM

AFF

AFFC

CRM

TDFM

COLC

SACECHRGPBDCE or PLCE

active SACECP

b. Detailed billing output to a billing centre

If the detailed billing records have to be transferred to a billing centre, the FileTransfer, Access and Management (FTAM ) protocol is used over X.25 links. FTAMallows to:

– request files. This includes open, transfer and close a file;

– deallocate files.

Every file that has to be transferred has a unique virtual file name. FTAM supportsseveral virtual file stores. the Virtual File Store (VFS) FMM is located in the IPTMOX25.This module also handles the X.25 link to the billing centre.

The output to a billing centre is handled by two FMMs:

– the Massive Charging Provider (MCP) FMM:

MCP formats the files and transfers them to the billing centre. MCP is located inthe IPTMOX25.

– the Massive Charging Reader (MCR) FMM:

MCR reads the files from disk and transfers them to MCP. MCR is located in thePBDCE or the PLCE.

In addition also a Q3 interface can be used to transfer the detailed billing records to abilling centre. In this case a dialogue is possible between the billing centre and the localexchange.

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8.8.3 Division of revenue output

The Division Of Revenue Collector Output FMM (DORO) is responsible for the formattingand transmission of the accounting results, collected by DORC. The counters can be sent totape, NSC or/and printer.

The DORC–files are reformatted by DORO into DORO– files. DORO gets the data to formatfrom DORC via 2K buffers, while the backup process keeps running in DORC.

These actions of DORO are scheduled in time :

� every 24 H: DORO stores the counters for output in a daily file. For security also the lasttwo daily files are kept.

� every of month: the monthly accumulated files are adapted. Two files are kept for the last2 months.

On the same times, also a printout is generated of the same data. This can also berequested immediately by the operator.

At the request of the CRM (via NSC or Man Machine), DORO can be asked to output itsdaily and monthly files to tape or NSC.

In case the operator requests current counter values, DORO sends a request to DORC.

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9. MAINTAINING AN A1000 S12

9.1 System and microprocessor initialization

Before the system is started, it is necessary to transfer the software from the disks to allsystem microprocessors (CEs and OBCs). This operation is called System Initialization.

Furthermore, during the operational life of the exchange, certain CEs and/or OBCs mayhave to be downloaded again from disk due to failures. Each individual load is known asReload .

However, some failure situations will be solved by simply starting up the software alreadycontained in the memory of the faulty CE. This software ’start’ is also performed after a CEload (at system initialization), as well as after a reload. This procedure is known as Restart .

9.1.1 CE initialization

The CE download consists of the transfer of the software packets (GLS, PLS and DLS) fromdisk into the microprocessor memory due to power–on, the detection of certain types of CEfailures (eg. when there is strong evidence that the write–protected memory has beenmutilated), following a forced request from the maintenance software or an operatorcommand.

Every microprocessor has a program called Bootstrap stored in ROM. This program, whichallows for the download and the initialization of the control element, is identical for all theControl Elements.

First, the Bootstrap decides, based on the reason for its triggering and/or on the data in therequest message, whether or not it is necessary to perform a series of fast tests to verify thecorrect operation of the CE elements (TI, memory and CPU). When the tests are finished orwhen the Bootstrap has decided that they are not necessary (’reload’ operation), theBootstrap program continues by trying to obtain its load packet.

Since the PLADMCEs are the only CEs able to access to the system tape and disks, theyare responsible for sending the load packets to the requesting CEs through the DSN. Theirdownload process is therefore different from the other. Thus, first of all, the Bootstrapprogram must check if it is located inside a PLADMCE or in another CE. To do so, theprogram tries to reach the DMCA board, an operation that will only be successful if the CErequesting the load is a PLADMCE.

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Figure 345 : Bootstrap triggering

CE ROM

Bootstrap program

Fast Test

BOOTSTRAP

– Power–on– Forced– Error detection

Triggering reason

RELOAD?

? OKNot OK

CE failure?

Any other CEPLADMCE

DMCA access attempt

ANY MODULE

Not OKOK

If the CE is not a PLADMCE, the Bootstrap program continues by requesting the downloadfrom the P&L modules. The Bootstrap program needs to establish a path through thenetwork in order to send a message requesting the load. Although it knows the messagedestination address because the PLADMCEs are located at the same addresses in all theexchanges, it does not know its own, the origin address. Because of this, the Bootstrapapplies a special algorithm to be able to send the request message to both PLADMCEs fromany CE address and any DSN equipment.

The algorithm involves of the sending of a set of sequential messages as follows:

First attempt:

Three stage message to PLADMCE–1 Three stage message to PLADMCE–0

Second attempt:

Two stage message to PLADMCE–1Two stage message to PLADMCE–0

and so on.

Whatever the number of DSN stages equipped, one of these attempts will reach thePLADMCEs successfully.

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Let us take the TREX example again, where the JLTCE (NA=0220) tries to reach thePLADMCEs (NA=000C and NA=000D) .

The first attempt consists of two messages with seven SELECT commands. The sequenceis:

A. Switching towards any low port of the AS

B. Switching towards any port of the first stage GS

C. Attempt to switch towards any port of the second stage GS

D. Since there are only two stages, this last command is not acknowledged, and thewhole attempt becomes unsuccessful.

Figure 346 : Unsuccessful JLTCE–to–PLADMCE connection

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STAGE 1 STAGE 212

013

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13

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉPLADMCE

1

2

2

6

JLTCE

0

0

A

B

C

D

After a time–out, the JLTCE Bootstrap program again tries sending two more messages withfive SELECTs commands. These are:

A. Select low portB. Select any portC. Select port 0D. Select port 0E. Select port C (in one case) or D (in the other one).

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As we can see in the figure below, the attempt is successful with this set of commands.

Figure 347 : Successful JLTCE–to–PLADMCE connection

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STAGE 1 STAGE 212

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13ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉPLADMCE

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6

JLTCE

0

0

A

B

C

D

E

In order to provide the PLADMCE with the requesting CE Network Address, the DSNsupports a special kind of ESCAPE protocol called ESCAPE INTERROGATE which ischaracterized by an Interrogate Flag set to ’True’. This command includes three fieldscontaining a pointer, a port number and a channel number.

A set of these commands, with decreasing pointer values, are stored at the end of the loadrequest message. When this command is switched at a multiport, the pointer value isdecreased by one. If the new pointer value is not equal to zero, the command is simplypassed to the output port. If, on the contrary, the pointer value is equal to zero, the multiportwrites the input port and channel numbers into the corresponding fields and sets the pointerto seven. In this way a trace of the path already covered by the message is kept.

The figure shows how this method works in the first multiport of the established path forreasons of simplicity the channel number field is not shown.

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Figure 348 : Escape Interrogate example

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STAGE 1 STAGE 212

013

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13ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

PLADMCE1

2

2

6

JLTCE

0

0

ESCAPE INT. FLAG INPUT PORT NUMBER FIELD POINTER = 1

POINTER–1 = 0

ESCAPE INT. FLAG INPUT PORT NUMBER = 0 POINTER = 7

POINTER–1 = 6

POINTER–1 = 5

POINTER–1 = 4

POINTER–1 = 3

The complete load request message will therefore have the same structure as shown on thefigure below:

Figure 349 : Structure of the load request message

UP TO 7SELECT COMMANDS

TO REACH A PLADMCE

LOAD BIT PACKET

DATA

7 ESCAPE INTERROGATE

Once the request is accepted and the address of the requesting CE known by the P&Lmodules, the associated load packets are split up into blocks and sent through a held path to

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the requesting CE. The Bootstrap program collects all the blocks received and stores theminto memory.

On completion of the CE load, the Bootstrap function terminates and a new RAM moduletakes control of the CPU to drive the initialization of the CE. This initialization, called Restart,consists mainly of cleaning all the Operating System data (queues, pointer, etc.) andcreating all the FMM supervisory processes.

If the CE reload is requested through an operator command, it is possible to indicatewhether the reload should be complete or partial. In the case of a partial reload, the requestcould e.g. inidcate to reload only the GLS and PLS packets, or only the DLS packet.

The Bootstrap sequence for PLADMCE is quite different. First, it tries to get the load packetfrom its mate P&L module through the network (as seen for any other CE) (step A on thefigure below). However, if this operation fails for some reason (eg. the other PLADMCE isnot on–line) the Bootstrap starts the ’Query–VDU’ procedure.

This procedure starts by placing a question mark on the VDU screen connected to a MMCchannel (step B1). Then, if the operator answers ’O’ to the question, the packet is loadedfrom Optical Disk (OD) or if the operator answers ’Y’, the packet is loaded from tape (stepB2); if, on the other hand, the answer is a negative or there is no answer before a time–out,the packet will be loaded from its own disk (step C).

Figure 350 : PLADMCE download sources

CE ROM

– Power–on– Forced– Error detection

Triggering reason

PLADMCE 1

PLADMCE 2

Bootstrap

?

ÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

CA

B1B2

In the first case, when the operator replies ’Y’ or ’O’ to the query after placing the SystemLoad Tape on the Magnetic Tape Unit or the System Load Disk in the OD (steps 1 and 2 on

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the figure below), the software is loaded into the P&L module (GLS, DLS and PLS, step 3).This procedure is called the disk–build, which is necessary to copy all the software from tape(OD) towards the system disk.

As soon as the disk–build procedure is completed (step 4), the PLADMCE will reboot (step5).

Figure 351 : Disk Build

PLADMCE 1

PLADMCE 2

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

1

3

2A

2B

4

4

4

’ YES ’

5

Once the download is completed, a request is sent from this CE to its mate to solve theActive/Stand–By status. If there is an answer to this request, the mate CE takes the Activestatus and the just–loaded CE the Stand–By one. If, on the contrary, there is no answer, theCE considers its mate to be off–line and takes the Active role.

9.1.2 System initialization

a. Network Loading

The System Initialization or System Start–Up consists of loading the systemmicroprocessors (CEs and OBCs) from disk and their start–up. This procedure is triggeredby the operator, and driven by a set of configuration and load data on disk.

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The System Start–Up may be performed as part of the system installation or when theoperator judges that only a full system initialization will recover the system from acatastrophic failure (Emergency Start–Up).

When both PLADMCEs are on–line and at least one disk is mounted, it is possible to carryout the System Init. To start–up the system, the operator uses a MMC command, whichtriggers the P&L software responsible for this task.

First, the software asks the operator for the system start–up confirmation. If it is confirmed,the initialization software inhibits, in both P&L, the triggering of the load software in order toavoid individual CE download requests.

The download of all CEs in the system is shared between the active and the stand–by P&Lmodules. The software of each P&L module collects the download information that containsthe list of the CEs to be loaded from the Database. The Active module sees to the CEsincluded in that list and the Stand–By one takes care of the remaining CEs.

Since the GLS and PLS are the same for all CEs of the same type, the initialization softwarefollows the ’cascade’ procedure. This procedure is as follows:

1. In order to place all CEs in a download request state, the initialization softwareforces all of them to trigger the Bootstrap program (forced bootstrap).

2. A handshaking overlay module is distributed from the PLADMCEs to all CEs.

3. Once this particular module is loaded in all CEs, the PLADMCE selects oneprocessor of each type to act as the ’source’ CE. Then, using the handshaking module,the PLADMCE loads it with the common part (GLS and PLS) and a task list indicatingwhich other CEs have to be loaded.

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Figure 352 : Distribution of the handshaking module

PLADMCE 1

CE list

PLADMCE 2

CE list

JLTCEs

DCASTCE

ISVTCE

IPTMN7

ACEs

HANDSHAKINGMODULE

HANDSHAKINGMODULE

Figure 353 : Load of the Common Part files into the source CEs

PLADMCE 1

CE list

PLADMCE 2

CE list

JLTCE

DCASTCE

CECOMMON

PARTFILES

ISVCE

IPTMN7

SCALSV

DFN7OCE

CECOMMON

PARTFILES

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Steps 2 and 3, as described above, are then repeated by the ’source’ CEs according to theirtask lists. This process is chained until all CEs of the same type are loaded.

Figure 354 : Download in Cascade

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

SCALSV

SCALSV DFN7OCE

DFN7OCE

DCASTCEDCASTCE

DCASTCE

DCASTCE

ISVTCE IPTMN7

IPTMN7

IPTMN7

ISVTCE ISVTCE ISVTCE

As for the load of the DLSs, the P&L module will not follow the previous process since thethey are different for each CE. Instead, it will send the DLSs one by one to each CE.

Since the PLADMCE memory is used as interface between the disk and the CEs during thesystem load, it must be cleaned at the end of the process. Therefore, a bootstrap operationwill be carried out in both PLADMCEs.

Where only a partial system initialization is required a parameter in the’SYSTEM–START–UP’ command will be used. This parameter allows either the reload of acertain set of CEs through the definition of a list of CE types, or the load of only the newones (in the case of an exchange extension). In this partial system init, only a PLADMCEworking in simplex mode is used to perform the load.

b. Tonebus System Loader

The tonebus system loader software is a recently developed system which utilizes the tonebus for down–loading, from system disk :

– the GLS’s which are common to a large number of CE/OBC processor types

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– the replicated data (i.e. any part of a DLS which is replicated in a large number ofCE’s)

The Tone Bus System Loader software, however, still uses the Digital Switching Network(DSN), for downloading from system–disk :

– the GLS’s which are common only to a small number of CE/OBC processor types

– the DLS’s

By using the tone bus, the GLS’s and replicated data that are common to a large number ofCE/OBC processors, can be distributed in parallel, without any switching involvement fromthe DSN.Prior to the distribution of this information itself, first the Tone Bus System Loader softwaremust be loaded in all CE’s of the exchange. The Tone Bus System Loader software consistsof three parts :

� the Master software runs on the P&L, and controls the entire loading operation, whichinvolves the following items :

– loading the load sources with the Load Source Master software, load tables ,non–tone bus GLS’s and DLS’s

– loading of the Tone Bus Slave Loader software into the target CE’s

– loading, via the tone bus, the common GLS’s and replicated data into the targetCE’s

� the Load Source Master software runs on the load sources, and is responsible for theloading of the non–tone bus GLS’s/DLS’s into their respective CE’s.

� the Tone Bus Slave Loader software is loaded into the target CE’s and into the Clockand Tones Module (CTM); this software is necessary in the target CE’s for the correctreception of the load packets via the tone bus, and in the CTM for preparing thesepackets for sending over the tone bus.

Figure 355 shows the distribution of the Tone Bus System Loader software within the CE’sand also the data paths that are used during the loading process.

The Master software is activated by an operator command to begin the loading process.When activated, the Master software accesses the hardware configuration files on thesystem disk to obtain the identities of all equipped CE’s with their network addresses. TheMaster software then enters the stand–alone operating mode by gaining control of the P&Land stopping all software running in it.

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Figure 355 : Tone Bus System Loader

MASTER

SystemDisk

P&L CE Active

Stand–by

Tone Bus Slave Loader

CTM TCE ActiveStand–by

Tone Port

Tone Bus

Load Source Master

Spare CELoadSources

Tone Port

Tone Bus Slave Loader

CETargetCE’s

Note : 1.2.3.4.

CE = Control Element, CTM = Clock & Tone ModuleThe channels of the tone bus por are routed via the DSN Access Switch tothe network ports of the CE

= Bulk Data Paths= User Controlled Path

(See note 4)

After activation and entering the stand–alone working mode, the Master software performssome preparation functions, such as :

– arranging the data into sorted tables, where the information is assembled regardingCE’s/OBC’s which require the same GLS’s

– initialising the load sources by sending a boot–request message

– setting up a bulk–data path to each load source, and send to each of them the LoadSource Master software, and the actual GLS’s and DLS’s which are to be loadedover the DSN into the target CE’s

– initialising the target CE’s by sending a boot–request message

Before the target CE’s can receive their load packets via the tone bus, they first must loadthe Tone Bus Slave Loader software : this loading is shared by both the Master software andthe Load Source Master software :

– the Load Source Master software first loads via the DSN, a first part of the Tone BusSlave Loader software, enabling these CE’s to accept packets from the tone bus

– the Master software then sends over the tone bus the second part of the Tone BusSlave Loader software, which comprises the OBC Slave Loader software, and theDebug software.

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Once the target CE’s are loaded with the Tone Bus Slave Loader software, the real loadingcan start :

– the common GLS’s and replicated data via the DSN to the Clock and Tone Modulefor distribution over the tone bus

– the load sources, loaded with the DLS’s and GLS’s which are common only to asmall number of CE/OBC processor types, now begin loading each of theirassociated target CE’s via a DSN bulk data path

– the OBC GLS’s are loaded by the OBC Slave Loader software

After the loading phase, each target CE reports the success, or failure of the loading to theMaster software, which then :

– sends a tone bus broadcast message to all target CE’s, instructing them to run thenewly–loaded software

– presents the report of the loading process on the system printer

– returns control of the P&L to its operational software by rebooting it

c. Warm Start–Up

A strategy different from the complete system start–up is the ’Warm Start–Up ’. The WarmStart– Up provides a fast reload for package replacements in on–line exchanges. Thisprocedure keeps most of the exchange CEs on–line during most of the time spent on thepackage replacement. This kind of system start–up, ’Warm–Start–Up’, is triggered by anoperator command.

One of the disks will hold the old SW (current package), while the other disk is built from thenew System Load Tape or optical disk. The PLADMCE associated with this magnetic disk isloaded with the new package (following the above–described PLADMCE downloadprocedure) and isolated from the rest of the system.

The following figure shows how this strategy works.

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Figure 356 : Warm Start Up triggering

PLADMCE 1

PLADMCE 2

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

’ WARM START UP ’

New SW versionpackage

only one disk withnew SW version

1

2

22

3

3

The procedure to be followed by the initialization software in this case, is very similar to theprevious one (known as ’Cold Start–Up’). In order to keep the system CEs on–line, only alimited set of selected ’source’ CEs (which will start the dumping of the common part incascade) are booted (driven off–line) and loaded with a GLS or different DLSs, together witha task list.

The selection of the ’source’ CEs is made in such a way that the normal operation of theexchange is not significantly disturbed (i.e. SPARE, MONI, ITTMTCE, etc.). In case of anexchange extension, the new CEs are used as ’source’ CEs.

Once this process is finished, the other CEs are booted and loaded from the different loadsources.

At the end of a Warm System Start–Up, all the source CEs must be reloaded with their ownload packets.

During an on–line replacement, whereby the message and data interfaces are changed, theinitialization software must make sure that the two packages do not communicate with eachother.

The following figures show the Warm Start–Up cascade process.

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Figure 357 : Download of some of the source CEs in the TREX

PLADMCE 1

CE list

PLADMCE 2

MONI

SPARE

COMMONPARTFILES

ITTMTCE

JLTCE FILES

DCASTCE FILES

IPTMN7 FILES

Figure 358 : Download from the source CEs in cascade

JLTCE

MONI JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

JLTCE

SPAREDCASTCE

DCASTCE

DCASTCE ITTMTCE

IPTMN7

IPTMN7

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9.1.3 OBC initialization

All the TCEs that contain loadable OBCs, contain some resident modules to carry out theOBC load control.

These modules manage the OBC status and are able to drive an OBC restart or a reloadtriggered by an operator command or by failure conditions. In the case of an OBC reload,these modules send a request message to the PLADMCEs in order to get the OBC load filesand send them to the requesting module. These OBC management modules collect the loadpackets and send them, through the OBCI, towards the OBC memory. Finally, an OBCrestart is forced.

Figure 359 : OBC download

PLADMCE 1

IPTMN7 CE Load Source

CE

TI

CE memory OBC memory

OBCOBCI

IPTMN7

CE – GLS + PLS

CE – GLS + PLSCE DLS

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

OBC – GLS + PLS

On the other hand, the system start–up (Cold or Warm) includes the OBC initialization. TheOBC packet is a GLS and optionally a PLS. The packet is loaded from the PLADMCE intothe TCE memory, using a reusable area such as, for example, the overlay zone or anotherfree zone if enough memory is available. When the exchange is started, the SW of the corresponding TCE transfers the OBC file fromthat memory into its own OBC (or OBCs), in the same way as seen above. This task is partof the TCE initialization.The OBC doesn’t receive a DLS. The necessary data is retrieved from relations included inthe DLS of the CE. This data is extracted and transmitted towards the OBC(s) by FMM(s).

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9.2 Introduction to maintenance

The maintenance function of an ALCATEL 1000 S12 exchange deals with the task ofmaintaining the system at the highest possible grade of service level. The maintenancefunctions can be divided into two main categories:

� Preventive maintenance

� Corrective maintenance

Preventive maintenance includes those tasks that identify potential faults before they occur.Corrective maintenance includes those tasks that isolate and correct fault conditions

An ALCATEL 1000 S12 exchange has extensive self–monitoring and fault handling facilitieswhich ensure that a hardware or a software fault has a minimum effect on the exchangeoperations. The objectives of the ALCATEL 1000 S12 maintenance strategy are to ensurethat the system effectiveness is met. System effectiveness is defined as a measure of anexchange’s ability to function normally and to cope with internal hardware and softwarefailures or other events that could disturb normal operations.

The ALCATEL 1000 S12 exchange maintenance is designed around self–supervisory andself–diagnostic procedures. The strategy calls for the performance of maintenance taskswith a minimum interruption of normal traffic. The necessary maintenance tasks includerapid detection, analysis, identification, alarm signalling and detailed fault reporting. The faultreporting includes internal software notation and a printed report to the exchange personnelfor these tasks. The functional maintenance software is called the MAINTENANCESUBSYSTEM and the hardware is arranged in functional units called SECURITY BLOCKS.Whenever the analysis by the maintenance subsystem determines that a hardware faultexists, the functional unit which carries the fault will be put out of service. The maintenancestrategy reduces to a minimum the effect of a fault on the exchange’s call carrying capacity.

9.3 Hardware and software used in maintenance

The functions of the maintenance subsystem are divided into a so–called centralized partand a decentralized part. The centralized functions are located in a special System–ACE,which is called DFCE (Defence Control Element) and the P&L (Alarm system), thedecentralized functions are located in every CE:

� Centralized functions

– Coordination of all maintenance functions and central control of decentralizedmaintenance functions

– Frequent access to maintenance data

– Interface to mass memory devices and I/O–devices

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– Central fault analysis

– Treatment of alarms

– Fault localization (tests)

� Decentralized maintenance functions

– direct access to the supervised module

– fast local error handling, fault detection

– Alarm detection

The corresponding Hardware is shown in the following picture:

Figure 360 : Hardware configurationVDU

P&L

CLMA RLMC

MAPMTU

PTR

CE

MCUB

switch

switch

switch

DSN

CE

MCUB

ODK

MD

CE

MCUB

Alarm Inputs

Clock &Tones

TAUC

CE DTM

PCM

Test Equip-ment

CE TTMCE

MCUBTSA

CTMClock & Tonesdistribution

CE

MCUB

CE CE PTCE

MPTMON Terminal

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Figure 361 : Maintenance SW distribution

P&L ASM

DTM

TTM

DFCE

CTM

PTCE

CE

CE

LEADH–FMM/SSM

LEADH–FMM/SSM

LEADH–FMM/SSM

LEADH–FMM/SSM

LEADH–FMM/SSMTest Resources(TSA)

LEADH–FMM/SSMRack alarm DH

LEADH–FMM/SSMReconfigurationTest (Fault localisa-tion)Operator Maint. cmdsSystem Defense

LEADH–FMM/SSMAlarm handlingI/O treatmentAlarm reporting

LEADH–FMM/SSMRack alarm DH

DSN

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9.4 Maintenance concepts

9.4.1 Definitions

a. Security block

Until now, errors in functional units usually led to their failure. Many errors, however,only affect a few circuits with limited subfunctions of a unit, so it can be wise to isolatethese circuits and allow the remaining functions of the unit to continue to work. In orderto do this, it is necessary to define clearly delimited areas whose operational status canbe controlled under security aspects.

Such an area is called Security block (SBL)

– A security block (SBL) consists of a limited number of circuits in the hardware whichperform certain related functions.

– Should one function fail then all other functions within the affected SBL also fail.

– Therefore it is possible to remove the entire security block from operation bysoftware without further affecting total system operation.

– Security blocks thus represent the smallest subunits in the system which, ifnecessary, can be reconfigured by software.

– The sum of all SBLs covers the whole system.

b. Replaceable item (RIT)

is the smallest identifiable unit which can be replaced for maintenance purposes(PBAs, power supply units, cables, I/O–Devices ...). Each security block thus consistsof one or more replaceable items.

Use:

As part of automatic error correction (error localization) a diagnostic program has thetask of identifying the replaceable items (RIT) suspected of being faulty within a failingsecurity block (SBL). When finished, the following information is given:

– the SBL type (with address)

– the RITs

– the RIT location coordinates (suite, rack, subrack, location).

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c. Repair block (RBL)

Before replacing a replaceable item, it is necessary to remove from exchange traffic allsecurity blocks contained in the appropriate repair block. These security blocks arethen switched off. Because this action represents a reduction of redundancy, repair hasto be done as quickly as possible in order to reestablish full redundancy.

Example:

The power supply must sometimes be switched off in order to replace a faulty RIT. AllSBLs which belong to the RBL being fed by the corresponding converter must first beswitched off by use of special MMC–Commands.

d. Device

The system can also be split up into functional units or so–called devices. This conceptis only used by the device handlers and maintenance has knowledge about it wheninterworking with device handlers.

The device type specifies the type of the device and is different from the SBL type, so itis possible to have different hardware devices hidden behind the same SBL type(realization of different interface conditions, signalling procedures,...).

9.4.2 Relationship

a. SBL – RIT

A RIT can contain different SBLs, e.g. a line RIT can contain 6 or 8 line SBLs. An SBLcan also consist of more than one RIT, e.g. the SBL CTLE can consist of a processorRIT and a converter RIT.

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Figure 362 : SBL–RIT Assignment

SBL/RIT Assignment

PROC

2

4

5

1

3

0

1

7

Functional Units which can be handled by themaintenance subsystem

CE PBA

Converter

SBL=CTLE

SBL=TOPT

SBL=TASL

SWITCH PBA

SBL=ACSW

b. SBL – RBL

A repair block can but usually will not coincide with the SBL. A RIT can contain severalSBLs. There are hierarchical dependencies among SBLs, that a lower level SBL cannotbe in service if a repair is being done on a higher level SBL, and the repair block willalso contain the lower level SBLs.

When the PBA to be replaced is not ’hot insertable’ the power unit has to be switchedoff before the repair. That power unit can be common to other SBLs (e.g. commonconverter for different modules), so the repair block will also contain the other SBLs fedby the same power unit.

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Figure 363 : Repair Block

Repair Block (example)

Converter

CE1 CE2 CE3 CE4 CE5

CTLE CTLE CTLE CTLE CTLE

c. SBL – device

The mapping of SBL type to device type is not always one to one. The device types arenecessary, because a special SBL type can map onto different device types! Forexample:

SBL – Type Device – Type

ASST PrinterVDU

(ASST = asynchronous sharedterminal)

d. Security block hierarchy

The SBL hierarchy shows the dependencies between different SBLs with respect to theaccessibility seen from the DSN. So when a ’higher level’ SBL is out of service, theSBLs which are ’lower’ in hierarchy are not accessible any more. This will be reflectedin their maintenance states. Therefore in case an SBL has to be taken out of service,all its lower level SBLs will also be taken out of service.

– The SBL hierarchy of a control element, which is the SBL–Type with the highestlevel, comprises maximum five levels.

– If a security block is removed from operation, all its subordinate security blocks aregenerally also (automatically) taken out of operation since they would not befunctional alone.

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– Information about the hierarchy of SBLs is given in the Support Information SI05.

Figure 364 : SBL–dependencies

SBLIN TRAFFIC

FAILING

SBL

SBLSWITCHED OFF

SBLSWITCHED OFF

SUBORDINATE SBLs ARESWITCHED OFF AUTOMATI-CALLY

As a result of error analysis thisSBL is switched off in order to isolate the error.

ERROR

SBL Hierarchy

High

Low

e. Security block categories

Although all SBLs are treated more or less in the same way. Some differences exist.Also some SBLs require a similar kind of treatment. Therefore the whole number ofSBLs are grouped in five categories.

– Control element (CE) All control elements

– Network (NET) comprises all SBLs within the Digital switching network such as Switch elements,Links between Switch elements...

– Telephonic (TEL) groups all SBLs related to lines, trunks, receivers....

– Peripherals (PERI) includes disks, tapes, printers...

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– System (SYS) all SBLs related to the clock and tone system,...

9.4.3 Security block states and state transitions

Security blocks can be in different states whereby each state specifies in which manner thesecurity block is part of the operation or isolated from the operation. An overview of thesestates is given below:

� IT In Traffic: An SBL in service is able to carry traffic, it is in full operation.

� EF External Fault: The SBL cannot carry traffic if the fault on the SBL is external to the exchange.

� FIT Faulty, but in Traffic: If a small error is detected during a diagnostic test, the SBL keeps on handling traffic, butmaintenance is informed of the error

� FLT Faulty: (error detected by the system) Due to the function in the SBL itself, more than apredetermined number of service–affecting faults have been encountered and themaintenance subsystem has confirmed these faults. The derived state is FLT. The SBL isinitialized automatically by the maintenance subsystem when the fault has beencorrected.

� FOS Faulty out of Service: Similar state to FLT, but the SBL is not initialized automatically by the system after thefault has been corrected. The SBL initialisation in this case is a task of the operator.

� OPR Operator out of Service: Following the request of an operator to take a particular SBL out of service. These SBLscan only be restored to service when the operator allows it.

� SOS Software out of Service: Due to a failure of another SBL, the SBL itself is not faulty but a higher level SBL in thesame control chain has been taken out of service, or the repair block to which this SBLbelongs has been taken out of service. The SBLs out of service for this reason can bereturned into service as soon as the system allows it. This is done automatically by thesystem.

� The following states are not accessible for maintenance:

NEQ Not Equipped: The SBL is not equipped hardwarewise and no data is foreseen softwarewise. The SBL isnot declared in the configuration.

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PEQ Partially Equipped: This state is only used for Network Link SBLs

EQAWL Equip allowed: The SBL is declared in the configuration, but not physically present.

a. SBL state transitions

An ALCATEL 1000 S12 – Exchange in top condition consists of SBLs in traffic only.The SBL states NEQ, PEQ and EQAWL are not taken into account because thecorresponding hardware is physically not present in the exchange.

The maintenance state of an SBL can change due to maintenance actions requestedby the operator, or autonomous actions supported by the Maintenance Subsystem.

Three basic maintenance actions on SBL are possible:

– DISABLE The SBL will be put out of service.

– TEST A diagnostic test will be started on the SBL.

– INITIALIZE The SBL will be put into service.

These three actions can be started internally by the Maintenance Subsystem or by theoperator via the corresponding MMC–Commands.

The combinations of two or more basic actions are called combined actions:

– VERIFY This command consists of three basic actions, first the SBL will be disabled, then itwill be tested, and if the test is successful, it will be initialized.

– REQUALIFY This command consists of two basic actions, first the SBL will be tested, and if the

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test is successful, it will be initialized.

SBL–state transitions

Maintenance action Begin state End state

Internal disable after external fault IT EFInternal put faulty FITInternal disabled/Verify FLT/FOSInternal/Operator Maintenance action disable on higher level SBL SOSOperator disable OPR

Operator disable EF OPRInternal initialize IT

Operator disable FIT OPR

Operator disable FOS/FLT OPR Operator requalify (Test o.k.) IT

Operator test (test o.k.) OPR OPR(test not o.k.) FLT

Operator initialize OPR ITOperator Requalify (test o.k.) OPR(test n.o.k.) FLT

Internal/operator maintenance action Initialize on higher level SBL SOS IT

9.4.4 SBL management on CE Level (SBL=CTLE)

SBL Management on CTLE, e.g. disabling or initialising, is the same as the handling of allother SBLs. There is an extended number of commands for this SBL–Type that affect theSBL states involved and their hierarchical organisation.

Redundancy (modes of operation)

� Duplication of critical modules having a great failure impact, e.g.:

– Peripheral and load – module (P&L)

– Defence module

– Clock and Tone Module

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– Auxiliary control element (ACE) for collecting charging information (CSAC)

� ”SPARE” redundancy for less critical modules having a lower failure impact, e.g.:

– Auxiliary control element for traffic measurement tasks (MSAC)

– Auxiliary control element for administrative tasks (ASAC)

Modules having a low failure impact do not have redundancy for economical reasons (e.g.Spare – ACE).

Low failure impact along with expected reliability means that it is unjustified to provideadditional redundance (redundance becomes more expensive the closer it must beimplemented to the line (HW) which itself is not redundant!)

Spare replacement is applicable to CEs with spare redundancy. Spare replacement can betriggered on different conditions.

When internal or operator requested actions decide to replace a certain CE by a spare or tointerchange two TCEs, the initial configuration is disturbed. The return to the initialconfiguration consists of the replacement of faulty ACEs by spare CEs and interchangingTCEs which are not in their initial configuration.

The ALCATEL 1000 S12 exchange is in its initial configuration after a System–Start–Up orwhen a special MMC–Command is successfully executed. In the meantime the configurationcan be changed by the operator or by autonomous maintenance actions.

Initial configuration means that the function of each CE, fixed to a so–called logical CEidentity, is stored at a predetermined network address, the physical CE–identity. Due tospare replacement, the logical CE identity and thus the function of a CE can move toanother network address within the same exchange. The initial configuration is thenchanged.

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Figure 365 : Operational modes of control elements.

Duplication/Active/Standby)(A/S)

Spare pool

Simplex (SI)

2 X Simplex (Act/Act)

Loadsharing/SpareLo/Sp

Loadsharing/Active/StandbyLo/A/s

Crossover

Standby concept/characteristics

Each duplicated control element is loaded withthe corresponding user software and constantlyupdated (with data). In case of faults, a fastswitchover is possible.

A spare control element (spare CE) is NOT yetloaded with the corresponding application soft-ware. In case of an error it must first be assignedto the failing exchange control element type (re-configuration/reloading is necessary) This iscalled takeover

No redundancy

Duplication , both active (e.g: module for clocksignals and tones), quickest switchover.

The load is divided between several equivalentcontrol elements (with the same or even differentdata). If one unit fails, the spare CE takes over.

Several equivalent control elements share theload, each being protected by a standby CE.

Duplication of TCEs especially for subscriberconnections.

Normal operation: both modules are simplex.

In case of failure (failure of a control element,CE): takeover of the connection traffic by the re-maining CE.

9.4.5 Automatic error handling

With regard to:

� Rapid detection of the occurrence of a fault

� Analysis of the detected fault

� Isolation of the fault

� Alarm signalling about the fault

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� Detailed fault reporting

A fault can be either a software or a hardware fault. For software faults we assume thecorrectness of the own program, so a check must be done on the data used . The programdenotes the software package running in the control element where the fault occurs. Thedata used denotes the data stored in the local database DLS or the data retrieved fromincoming messages.

� Faults will be identified by

– ERROR TYPE

i.e. every failure gets a number and is attached to an Error Class

– ERROR CLASS

more detailed description of the kind of fault, e.g.:

• HW fault

• SW fault (OSN, application program)

• Notify only to operator

� Rapid detection of the occurrence of a fault. The rapid detection of the occurrence of afault is necessary to avoid the degeneration of the exchange call carrying capacity. Faultconditions on hardware can be detected by monitoring the hardware devices, periodicscanning, performing read after write checks when giving commands to the device, orchecking completion codes, or interpreting the interrupts received from the device. Thesechecks are performed by the responsible Device handlers.

� Analysis of the detected fault. The fault analysis will be done on different levels. Thelower level is in the control element where the fault occurs. This is part of thedecentralized maintenance functions, the responsible modules are called ERRORHANDLER (Part of the OSN) and the LOCAL ERROR ANALYZER (LEA). On this levelsome recovery actions can also be done. The higher level of error analysis takes place inthe DFCE control element (centralized part of maintenance functions), which has todecide on the action to be taken (e.g Internal Disable, Internal Verify,...)

The following autonomous recovery actions (”recovery level”) are possible:

1. No recovery (autonomous) 2. Abortion of process that causes the problem 3. Takeover to active (RAM Restart) 4. Restart (ROM Restart) 5. Reload (Bootstrap)

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Transfer of information to centralized maintenance – SW

No recovery action CE restart or process abortion or CE bootstrap

Anomaly report to centralized Restart/bootstrap buffer to centralizedmaintenance SW for further errormaintenance SW (after restart/bootstrap ishandling executed and end–of–restart message

is sent to centralized maintenance SW)

� The choice is determined by the error class and the fault origin

– In each case the central maintenance part in the DFCE will be informed.

– Overflows between the recovery levels are possible (by using timers, thresholdvalues)

� Isolation of the fault For hardware faults, the fault has to be verified, the faulty equipment has to be isolated soit will not be used any more by the call handling actions of the exchange and the operatormust be warned because the faulty equipment must be repaired and replaced by properlyfunctioning equipment.

� Alarm signalling about the fault Alarm signalling is necessary to warn the operator of the occurrence of a fault, which willbe done by an audible tone and a visual indication on the master alarm panel.

� Detailed fault reporting A report with all details of the fault will be printed on the system printer to give theoperator all the parameters needed for the action to be taken.

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Figure 366 : Main functions of maintenance

MAINTENANCE

PreventiveMaintenance

Corrective Maintenance

Scheduled RTby the system

Manual RT by the operator

Schedule planCalendar scheduler inthe system

Autonomousactions

Manual actions by the operator

Self monitoring error treatment

automatic errorhandling

RT on devices (different device types)

Maintenance actions – on SBLs, except CTLE – on SBL–type CTLE

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9.4.6 Corrective maintenance

Figure 367 : Corrective maintenance

PERMANENT SELF–MONITORINGSELF– MONITORING

ERROR

ERROR DETECTION

ERROR ANALYSIS (LEA)

SYSTEM DEFENCE

ERROR LOCALIZATION (DT)

SYSTEM REPORT

REPAIR ACTION

AUTOMATIC ERROR HANDLING

Error reporting to Local Error Analyzer

After Analysis DFCE will be informed

DFCE decides which action has to be performed

After completion of the autonomous action the operator will be informed

by a detailed system report

A specific task has to be performed by the operator

SYSTEM REPORTS TO THE OPERATOR

OPERATOR TASK

a. Corrective maintenance by maintenance personnel

Repair of an exchange is necessary in the following cases:

– for errors detected during preventive maintenance of input/ output devices or otheroperator actions (”Error correction due to malfunctions”)

– Error indications after routine tests automatically generated error reports (alarms)

– Error indicators for connected exchanges/subscribers (”Error handling due toexternal messages”)

The following tools are available for handling the errors:

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– Diagnostic test protocols and/or

– TP/DP (Area: C = corrective maintenance)

With the help of these it is almost always possible to replace the replaceable itemsuspected of error or to remove the error by readjusting mechanical items.

Procedure upon receiving a corrective maintenance task

Figure 368 : Corrective maintenance task

Repair Task

Task List O&M : TL(C)

Task Procedure O&M : TP(C)

Detailed task description

Additional lists and tables

O&M : DP...USI

O&M : Listsand Tables

O&M : Reportdescriptions

– Routine Tests. They run periodically under system control or upon operator request.Routine tests are intented to check the functions of devices in traffic (call handling isnot affected). (No influence on traffic).

9.4.7 Alarm system

Objective:

To make sure that in case of certain fault conditions the maintenance personnel will beinformed.

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Such faults, leading to an alarm, are handled in a specific way by special HW and SW parts.

==> Alarm system

a. Alarm type / Alarm groups

In order to distinguish the variety of possible alarm conditions the following is defined:

Alarm type:

Identified by: Name or identification number (e.g. CONV/43)

As certain alarm types will be treated by the alarm system in an identical way, severalalarm types are organised in an

Alarm group

Main alarm groups (defined in the Support information):

– Module alarms (Converter failures)

– Rack alarms

– General alarms

– external alarms (e.g. rectifier alarm, power failure, Master Alarms Panel)

– internal alarms related to AC FMM (e.g. overflow of alarm category or alarm list)

– SW alarms (e.g. malicious call)

– Miscellaneous alarms

– SBL alarms

– CE concerning (CTLE)

– other SBL Alarms

– SBL alarm: SBL state = FLT/FOS alarm on SBL state = IT alarm

– SBL group alarm: If the number of SBLs of the same type (e.g. digital trunk channels, asynchr. I/O–devices) being in the state faulty exeeds a certain threshold value, a SBL group alarm of a higher category than the single SBL alarm is issued.

b. Alarm class / categories

Information about the urgency of an alarm :

– Disabled

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– Print only

– Non urgent (not critical)

– Urgent (critical)

Every alarm has two categories (Alarm Category (ALMCAT) and a reducedcategory (REDCAT)). The purpose is to implement an easy ’category switch’ at acertain time of the day. E.g. during low traffic hours some alarms are not asimportant as during high traffic hours, so the corresponding category could be setlower.

The appropriate maintenance action to be taken by the operator personnel depends onthe urgency and the operational administration concept.

c. Alarm indicators

The most common alarm indicators are:

– Alarm panel

– System printer

– LED on PBAs (on CLMA–PBA)

– Alarms sent to Network service centers (NSC)

d. Components and functions

– The alarm system is part of the implemented exchange maintenance functions

– It can be attached to the following basic functions:

– Fault detection leading to alarms (alarm detection)

– Handling of alarm reports issued via alarm indicators

– Alarm causes can be HW or SW related.

– For implementation of the described tasks the alarm system consists of:

– Alarm HW Components (PBAs)

– Alarm SW Components (FMM / SSM)

e. HW–Alarm–Reporting Chain

HW–alarms are detected by two different Device–Handler(DH)–types, theRack–alarm–DH and the Central–alarm–DH.

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The established alarm condition is signalled to the error handler by the DH by means ofan ERROR_REPORT. The error handler sends a message to the DFCE via LEA.

The information on the alarm condition detected by the DH is then supplied to the FMMAlarm Control (leads to an alarm output).

There is an acknowledgement mechanism via a DB relation in order to inform the DHwhich detected the alarm condition that the message has reached Alarm Control andthat corresponding maintenance actions will be carried out.

To clarify this, the acknowledgement process for a HW–alarm is described below.

Figure 369 : Example: HW–Alarm reporting chain

ERRORHANDLER

LEADFCE

MaintenanceFMMs

Rack/CentralAlarm deviceHandler FMM

Rack/CentralAlarm deviceHandler SSM

1

2

3

4

5

6

78

9

5

DATABASEALARMCONTROL

DFCE

R_ALRECE

List of activealarms

Alarm report to IO system

located in P&L

Alarm report to alarm system

Anomaly report

to DFCE

in every CE

Error reported to the ERROR HANDLER(ERROR_REPORT)

HW Alarm Inputs

Indicators (e.g: Master Alarm Panel)

Indicator Drive Message

Example of alarm treatment:

The general treatment of an alarm condition is described in the following scenario:

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Figure 370 : Scenario

RACK ALARMPBA

ALARM DHSW

DATA BASESW

EH/MAINT.SW

ALARM CONTROLFMM

1. Alarm–PBA is scanned for Alarm Inputs

2. Change of Alarm Bit State is reported to ERROR–HANDLER

3. Maintenance Software sends Alarm Report

4. Alarm Control Software acknowledges Alarm Report and changes the indicator states.

5. Alarm DH Software is told to read DATA BASE

6. Alarm DH Software requests Indicator data from DATA BASE

7. Alarm PBA is told to activate Indicators

8. Alarm DH Software requests Alarm acknowledge data from DATA BASE

9. Alarm bits not acknowledged are reported again

1

2

3

4

5

6

7

8

9

Explanation of the individual processes:

Alarm–PBA is scanned on a cyclic basis for changes in the input states by thealarm–DH–software (64 alarm–bits).

If a change in the input state is established, the alarm–DH–software generates analarm report (alarm=on, alarm=off), which informs the Error Handler (EH) aboutthe change

The EH sends an error report message to maintenance software. The latter in turngenerates an alarm report, which is sent to alarm control software.

Alarm control evaluates alarm reports, enters the alarm in the database andgenerates a new state pattern for alarm indication.

ALC then informs the alarm DH software that a change in the alarm indicationstate has occured and that this is available from the database.

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Alarm DH software fetches the corresponding data from the database.

Alarm DH software switches the alarm indicators on the alarm PBA in accordancewith a new state pattern.

The alarm DH SW checks whether alarm control has acknowledged the alarmreport within six minutes after the error report was sent to the error handler (step2).

If there was no acknowledgement, the error report (step 2) is sent again.

– Device Handler for Module and Rack Alarms (Rack Alarm DH)

Software is resident in the modules which have a corresponding RLMC PBA (2per rack)

Scanning of the connected HW signals (voltages, clocks ...)

In case of alarm the respective error handler is initiated

The error handler sends a message to the Defence Processor, whose alarmcontrol initiates the further procedure. (Printout on printer, alarm indicators).

– Central Alarm Device Handler / Master Alarm DH (CAL–DH)

Software is resident in P&L

Driving the functions of the Central Alarm PBA (CLMA)

Scanning for external alarms

In case of alarm triggering of the Alarm Control FMM or the Error Handler(depends on the Alarm type) and triggering by the Alarm Control FMM forindicator driving

– Alarm Control FMM

Central SW module within the Alarm system SW

Software resident in P&L

Analyses the alarm event in the arriving messages and alarm identification

Controls the appropriate alarm treatment (data–driven)

Generates commands to switch on alarm indicators

On request, display of an active alarm at a specific time

On request, removal of a redundant active alarm from the system

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On request, display and/or modification of an alarm category of a specific alarmtype

– Alarm identification

* Alarm identification by – Alarm type – Alarm group – Alarm address

– Routing of alarm reports

It is possible to route special Alarm reports based on Network address, Alarm type andAlarm number to certain output sets. The operator is able to modify the ’normal’ Alarmrouting .

9.4.8 Preventive maintenance

Preventive maintenance for an exchange encompasses manual activities which must becarried out according to a fixed schedule to avoid failures in the hardware.

– Objects for scheduled maintenance

– Peripheral devices

– Exchange devices (telephonic devices, system devices,...)

– Tools

– Routine test programs (manual or automatically started)

– Built in HW–self test (after power on)

– device manuals

– Directions

– proceeding according to operation and maintenance guide (O & M–Manual: Task area (S))

– schedule: depends primarily on customer administration

– recording of the activities

a. Routine test

– Method of fault detection for preventive maintenance

– Functional tests of devices, not related to SBLs

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– Necessary: some Test recources

– Fault detection with test result restriction: GO/NOGO

– For functions not monitored by on–line or alarm supervision

– No operational disturbance as it runs only when devices are not under traffic (lowpriority level) Important: starting the routine test is only possible on SBL–state IT!

– Periodically scheduled automatically by the system itself or once called by operator.

– Execution with help of overlay test programs (TEX–FMMs=TEST EXECUTION) andpossibly some Test HW (TAU, TSA).

Telephone exchanges require a minimum amount of test and preventive maintenancetasks, which have to be performed in definite time intervals (”ScheduledMaintenance ”)

b. Scheduling

Information about scheduling intervals, given in tables, are recommended values andcan be changed on the basis of operational experience gained during systemoperation.

– Possible time intervals (I/O–Devices)

– yearly

– monthly

– weekly

– daily

– Recommendations about time intervals

– In appropriate preventive maintenance TP for the specified device (O & M Manual)

––> scheduling plan

– Scheduling

– Manually triggered by personnel when a fault is suspected.

– Automatically triggered (once, periodically) by system according to current scheduling plan (normally already on SLT!), mostly during low traffic period

– monthly, weekly, daily

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– Change possibilities

– When required, change of the scheduling plan by operator commands (MMC)

– Manually triggerable of a routine test or premature abort by MMC

– For every routine test a total result is output

9.4.9 Summary report for all scheduled routine tests

It is possible to start a routine test (scheduled!) for the whole number of devices in thenetwork (Device–Type: NETWORK). This test will run a very long time, (dependent on thenumber of devices in the network) and will produce a lot of system reports with the results ofthe test. Therefore a number of Commands have been created to make it easier for theoperator to check those results by using a so–called test summary report. This summaryreport includes the

– Test number and device type

– number of devices to be tested

– number of devices witout fault

– number of faulty devices

– number of busy devices, untested

– number of untested devices for other reasons (for example: no test resourcesavailable)

� Preventive Maintenance for peripheral devices

– include manual activities by maintenance personnel

– tasks like functional checks, cleaning, adjustments etc.

Examples of peripherals:

– VDU

– VDU on PTCE

– Line printer

– Magnetic tape unit

– Master panel for alarms

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– Preventive Maintenance Activities

– Kind of device checks:

– Visibility check

– Functional test

– Built–in self test

– On–line check

– Kind of activities on the device:

– Cleaning (box etc.)

– Lubricating (moveable mechanic parts)

– Adjusting (write/read head etc.)

– Replacement of used up parts (filter etc.)

– Additional activities:

– Make a protocol

– Possibly repair the device*

If during preventive maintenance a malfunction is detected whereby the device must berepaired, then a corrective maintenance action has to be performed, e.g. replacementprocedure. ”Error correction due to malfunction”

– Principle task procedure for preventive maintenance

– Prerequisites:

– Follow O&M–Manual (TL, TP, DP etc.)

– Preparation of aids

– Make a protocol (related to the device)

– Establish a definite SW state (SBL related)

– Establish a definite HW state (Device related)

– Important notes:

– Set the devices in or out of operation only in accordance with to the instructions

– Take notice of notes and precautions

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Figure 371 : Preventive maintenance

Preventive Maintenance

Task

Task List

Task Procedure

Execution

FunctionalError

Error correction bymaintenance personnel(Corrective Maintenance)

Detailed Procedure

Additional lists and tables

Device Manuals

O&M : TL(S)...

O&M : TP(S)

Scheduled Maintenance

O&M : DPUSI–Manual

Manuals

O&M : Lists andTables (Support

Information)

no,ok

yes

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10.OPERATING AN A1000 S12

10.1 IOS overview

10.1.1 Introduction

The Input/Output System Software is a part of the Alcatel 1000 S12 Operating System andits evolution is specified by the so called System Kernel Release (S.K.R.). An example isshown in figure 372.

It interfaces to the common Operating System modules, especially the Operating SystemNucleus which always runs in the background for support of resources such as processortime, memory space and timer, and the internal communication interfaces such as theMessage Handler, Network Handler, Cluster Handler, Message Interface, etc.

For data access the IOS needs help from the Data Base Management System.

With the above mentioned support the IOS acts as a SW interface for communication

between the operator with his peripheral devices and Alcatel 1000 S12 applicationprograms, to enable him to maintain and administer the exchange for fulfilling its task ofconnecting subscribers by phone calls.

The IOS is the interface between the application programs and the peripheral devices for fileaccess to get, store, modify, create or remove data if necessary, e.g. charging information.

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Figure 372 : SW specification for A1000 S12

HW+Firmware

OperatingSystem

Data Base

+

+

HW–family (J–family)

Evolutionary Call Handling (E.C.)Software Package

System Kernel Release :S.K.R. 7.1

10.1.2 IOS functions

The main tasks of the IOS are to support the operator facilitaties for exchange administrationjobs such as:

� File Administration

� ORJ Control and Scheduled Job Administration

� Command Administration

� Report Routing

� Password Administration

� Peripheral Device Administration Magnetic Tape and Optical Disk Handling

� Hard Disk Synchronization

� Device Anomaly Handling

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� Time and Date Administration

� Backup Generation

� Logging

Besides these tasks the following functions are performed by the IOS:

� Device Control

� Report and Command translation and queuing

� File synchronisation and recovery

� Translation between application programs, which have a logical view and the peripheraldevices which have to be accessed physically

� ’Twin’ and ’Fallback’ Device Organization.

For all these duties the IOS consists of some FMMs and SSMs (with specific communicationinterfaces (MSGs) and influencing several control relations.)

The I/O System (IOS) connects the user software inside the exchange with the computerperipheral devices. There are mass storage media like optical and magnetic disks, andmagnetic tapes. There are also the devices connecting the exchange with the outside worldlike the VDU, PC, printer or the modem for connection to remote devices.

Input/Output–System tasks (see figure 373):

� File Oriented tasks,

� Man Machine Communication (MMC) tasks

On the one hand, the user software inside the system requires access to data residing onmass storage devices and it also writes data to the printer or the VDU. Since the data isorganized in files, these actions are called file oriented tasks.

On the other hand, the MMC tasks handle all the communication between the supervising

personnel (operators) and the exchange. Operator Requested Jobs (ORJs) aresubmitted via the IOS to the responsible command handler software, which performs therequired jobs. The command handler software or any other user software module informs

the operators by submitting a report to the IOS. The IOS routes it to the desiredperipheral devices.

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Figure 373 : IOS functions

file oriented interface MMC – interface

applicationprograms

logical :– file, record– device– ID– ...

”USER”

– CRN– RRN– JSQ– ...

��

��

��

��

� ��

report MSGORJ

PSW and syntaxcheck, translation,report routing,device control,...

report

PSW,command

read,write,modify

Physical:– NA– block– name– ...

– command syntax or form– report layout– input/output device

10.1.3 Overall structure

The software for the Input/Output System is mainly located (see figure 2–3) in the Peripheraland Load Module (P&L). In addition, there may be another module, the AdministrationSupport and Peripherals Module (A&P), which relieves the P&L and of which more than one

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pair may be fitted to an exchange, for a Network Service Center (NSC) or an additionalOperator System).

One main task of the Input/Output System software is to translate logical data into physicaldata and vice versa between application programs (users) and the peripheral devices.

The user’s view of the IOS is a logical one. The user software must specify three attributesto get access to the data.

Logical view :

� Logical device

� Logical file

� Logical record.

A logical device is where logical files reside. It hides most of the properties related to thephysical device which it represents. Logical devices may be one of two types:

� Single device, which defines one primary and one additional fallback physical device

� Twin device, which maps two physical devices onto one logical device.

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Figure 374 : Logical and Physical View of the IOS

”user”(application

program)

generalremoteI/Ointerface

IOSP&L activeP&L standbyA&P activeA&P standby

IOS–MMC–interface

IOS_utilities

IOS–fileorientedinterface

peripheraldevices

log.device device typenetwork addressdevice number

log.filelog.record

phy.filephy.record

A logical file is a collection of logical records. It appears to the user as a contiguousinformation space in a linear arrangement (a string of adjacent records without gaps andbranches).

The logical record defines the minimum amount of data which can be transferred at a time.

The I/O System maps the logical items onto their physical equivalents. For each logicaldevice, one or more physical devices are defined in a device assignment relation(DASSIGN). On the physical devices, the logical files have their equivalent in physical files,as have the logical records with the physical blocks. This assignment is treated by theresponsible file handler software.

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A physical device is identified by its type, the particular control element to which it isconnected, and a device number by which distinguishes it from several devices of the sametype connected to the same CE.

Device types :

� disks

� magnetic tapes

� printers

� VDUs

� binary devices

� virtual devices.

The logical view will be mapped step by step onto its physical representation (see figure375). The user software must specify only the logical items. The general remote I/O interfacemaps the logical device to the network address to which it is assigned, the device type withthe responsible file handler and the specific device number. The next step is performed bythe responsible IOS interface which locates the physical file on the device and accesses thedata in physical blocks.

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Figure 375 : Functional Block diagram of the IOS

general remote

I/O–interface

file

management

report

routing

Device

Control

IOS utilities

(support functions)

logging

jobmanagement

MMC–translation

autorisationcheck

”user”(applicationprogram)

peripheraldevices

10.2 Hardware configuration

The hardware independent software (the I/O System software, will be considered in thisdocument) run in the MCUB of the P&L or A&P. When an action must be performed to drivethe peripherals, this hardware related action is ordered by the MCUB, which will pass theresponsibility to the DMCA. The firmware of the DMCA executes the desired peripheraloriented job. The peripheral processor of the DMCA and the I/O processor of the MCUBcommunicate via the multimaster bus (see figure 376). The mass storage media areconnected via the SCSI bus to the DMCA. The SCSI bus supports up to 8 device units:

� 4 disks (magnetic and optical)

� 2 DIL adapters with up to 16 magnetic tape units

� 1 streamer

� the DMCA itself

Two serial devices are connected to on–board channels 1 and 2 of the DMCA. Via theperipheral bus up to 4 MMCA boards can be connected to channel numbers 9....24).

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Figure 376 : IO HW configuration

RLMC

CLMA

MCUB

TERIPART

80386

DMCA

MMCA0

MMCA1

MMCA2

MMCA3

SYSTEM DISK

MAGNETIC

MAGNETICOR

OPTICALDISK

MAGNETICOR

OPTICALDISK

MAGNETICOR

OPTICALDISK

STREAMER

MTUF0

MTUF1

MULTIMASTERBUS

inter CLMA link

TODSNFROM

C&T ITF

64 ALARM INPUTS

4 rack alarm lamp driver outputs

16 EXTERNAL ALARM INPUTS20 LAMP DRIVER OUTPUTS2 remote lamp outputs

system printer

system VDU

4 x

4 x

4 x

4 x

PERIPHERAL BUSSCSI BUS

DIL8844

DIL8844

. .

. .. .. .

. .. .. .. .

1

2

3

4

5

6

7

8

01

02

06

05

04

03

00

9

12

13

16

17

20

21

24

The P&L and A&P modules are always duplicated and the pair works in active/standbymode. This means that when the active module fails, the standby module will take overwithout loss of service.

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It will, however, not be possible for a certain side of the P&L or A&P pair (active, standby) toreach a peripheral as long as it is not connected to that side. Using shared devices (seefigure 377) solves this problem for MMC peripherals connected to the MMCA or DMCAboards. This means that one serial device is connected to both sides, to the active andstandby side. So it is possible to reach this peripheral from both P&L modules. Only theactive member of the P&L pair has the right to use the shared device. Each serial channel ofthe DMCA and MMCA boards may be of shared or private configuration.

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Figure 377 : Shared Devices

DSN

MCUB

MCUB

DMCA

DMCA

CLMA

CLMA

MAP

MAP

RLMC

RLMC

MMCA

MMCA

MMCA

MMCA

DIL–adapter F

orm

atte

r

Tape

MagneticDisk

OpticalDisk

DIL–adapter Tape

For

mat

ter

Disk

OpticalDisk

Magnetic

SC

SI b

usP

erip

hera

l bus

9

1110

12

14

1615

13

1

2

1

2

910111213141516

Printer

Printer

Printer

Printer

Printer

Printer

PrinterO&MTerminal

O&MTerminal

O&MTerminal

O&MTerminal

O&MTerminal

O&MTerminal

O&MTerminal

Multimasterbus

Multimasterbus

ext. Alarms

ext. Alarms

Rack Alarms

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10.3 File–oriented interface

10.3.1 Introduction

All manipulation of information via the IOS file–oriented interface is bound to the Logical File.Transfers (read, write) occur within boundaries of that file for which exclusive ownership isgranted.

Within a file, the subunits of information handled during data transfer are Logical Records.

The IOS maps the logical items onto their physical equivalents:

� For each Logical Device, one or more Physical Devices are defined in the IOS data. Onthe other hand, one or more logical devices may be assigned to the same combination ofphysical devices.

� On the Physical Devices, the Logical Files have their equivalent in Physical Files, as wellas the Logical Records with the Physical Records. (Blocks)

The IOS has a remote part in each Control Element, which needs file access (to store,remove or modify data or for data requests), that means an application program resides insuch a CE, which uses the file–oriented interface of the IOS via a general remote I/Ointerface. This remote interface is responsible for translating the logical device given by theuser into a physical or logical device with the help of an assignment list. With the physicalinformation the IOS can be accessed in the responsible P&L (or A&P). The next job for the IOS is to check the availability of the destination device and file toaccess the requested data in the correct way. This way the functions of device control andfile management are covered by the IOS.

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Figure 378 : File oriented interface of the IOS

peripheraldevices

devicecontrol

file management& recoverymechanism

I/O–interfacegeneral remote file access

data transfer

file description

file status

filedirectory

DeviceCharacteristics

Device StatusLog. DeviceList

”user”(applicationprogram)

Which physical device(s)stand behind the given logical device–ID

... ...

Is the physical device equipped,available, in traffic,...

How is therequested physical devicedefined (type, protocol,configuration,...)

Where is the logical filephysically stored (blocks) ?

Is the requestedfile available, uncorrupted,...

How is the requested filedefined (length, type, access,...)

10.3.2 Logical file

A Logical File in Alcatel 1000 S12 is a collection of Logical Records identified by thecombination of a Logical File Identity (a number) and the identity of the Logical Device onwhich it resides. It appears to the user as a contiguous information space in a lineararrangement.

A file is viewed as a sequence of consecutive logical records.

The size of a Logical Record is defined in the File Descriptor Block (FDB) of the logical fileand can range from 1 to 2048 bytes. The record is numbered inherently by its offset from thebeginning of the Logical File, the ’record offset’ (see figure 379).

For each Logical File to be used in the system, a logical and physical file description (recordsize, access type, data type, authorization, maximum length, etc.) has to be set up andmaintained for on line use. This information is part of a File Descriptor Block (FDB). TheFDBs of all files in the system (max. 5000) are combined to a common directory called theFile Descriptor Table (FDT) which is itself a Logical File in the system.

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The FDT is produced off line and it knows about all files that are possible in the system (perdefinition). For all files an entry is available in the FDT. When a new file is introduced, thispredefined entry is modified. For this purpose, a utility is provided to enter new items into theFDT. Similarly, file descriptors may be deleted or (in a restricted manner) modified. For eachfile access the relevant FDB must be read by the IOS to prevent the file from being misused.An important part of the file description is the time constraints put on to the access of theLogical File, which is supervised by the IOS.

Figure 379 : Logical File

logical view of SW

. . .file 1 file 2 file 3 file n0

1

2

0123

0

1

2

0

1

recordlength

3

4

5

6

record offset

In addition to administering the file definitions in the file descriptor table, the “filemanagement” of the IOS has to check the actual file status in the file status list to see if it isavailable on the given physical device or not. There is an entry for each file, which is eitherheld by another user or intended for a recovery action or left in an abnormal condition by thelast user. If the file access is not allowed, the IOS gives an error message back to therequesting user. The operator can display all entries of the file status list or just somestatistics of it.

10.3.3 Logical device

The view of an Input/Output Device to the file oriented user is a Logical Device. This iswhere Logical Files (see before) reside, and it hides most of the properties related to the

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actual Physical Device which it represents. In Alcatel 1000 S12, a Logical Device may beeither:

– a Single Device or

– a Twin Device.

The Single Device defines a Physical Device for primary use (Primary Device) and,optionally, one or more Fallback Devices to be used when the Primary Device has failed.Also optionally, a Logical Device may have a default Logical File associated with it. As aresult, the user can access a file with the specification of the Logical Device alone.

The Twin Device (only for mass storage media, usually the disk) maps two Physical Devicesonto one Logical Device to achieve secure information storage and/or transfer. Thisduplication is invisible to the user FMM. An exception to this is when one of the twin devicesis not available. In this case the user receives a warning, indicating that the write operation isonly performed on one device. The user does not need to take notice of this warning,because the IOS starts an automatic recovery action during which the write operation isperformed on the second twin device.

Such files, which reside with the same definition in the FDB and the same contents on twophysical devices as one logical twin device are called “Twin Files”. Twin files are marked witha recovery flag in the FDB. The file management of the IOS is responsible for synchronisingthe twin files.

Write, modify and remove operations for a twin file will be performed on both PhysicalDevices simultaneously. Even if one of the two is unavailable, the Input/Output System willallow the operation to continue (entry in the file status list). When the device becomesavailable again, a recovery action will be performed for the file by the file management of theIOS.

� SOFTINIT

Synchronisation of files stored in the file status list by periodically scanning the list or byrequest.

� HARDINIT

The operator can trigger a Softinit for all twin files by a Hardinit and can display theactual status periodically.

� Emergency Recovery

To save twin files with an entry in the status list before taking one device out of service.

� Sector Recovery

To save twin files from physically destroyed sectors.

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Read operations from Twin Device will be performed on either of the physical devices.

10.3.4 Physical and virtual devices

From the user’s view, there is no difference between Physical and Virtual Devices.

A Physical or Virtual Device is identified by its type, the particular Control Element (CE) towhich it is connected, and a number which distinguishes from several devices of the sametype connected to the same CE. The combination of device type, network address anddevice number is called the Physical Device Identity. The following list is an extract of theactually available physical and virtual device types:

DEVICE TYPE DEVICE TYPE NUMBER

DISK 1

MAGTAPE UNIT 2

PRINTER 4

VDU 5

BINARY DEVICE 7

MPTMON 130 (virtual device)

REMOTE MMC 131 (virtual device)

DISK INIT COMM FACILITY 135 (virtual device)

The term Physical Device refers to what is connected as a peripheral to a control element forcommunication with human beings (VDU, BINDEV, printer), for mass storage and/ortransport of machine readable data (disk, magnetic tape), or for communication with systemsoutside the exchange environment (remote links to devices or EDP centres). A VirtualDevice can be defined as a process (an application of an FMM) which looks as if it providesaccess to a real computer peripheral. A Virtual Device can be used for inter–processorcommunication (e.g. DICF or MPTMON).

For each device access the device control of the IOS has to read the characteristics of therelevant physical device, which are defined in a list. The operator can display and changethese characteristics for HW modifications. Device type, protocol, (baud rate, parities),configuration (with or without modem/shared or private), the whole interface peripheraldevice/device driver must be specified for each physical device. A second list permanentlypresents the actual device states.

A device can be

– unequipped (no HW)

– unavailable (out of service)

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– available (free, busy or passive)

For operator devices automatic–in–service–routines exist, meaning that the IOS willperiodically try to bring them in service again.

For mass storage media with random access (disks) a file directory resides on it to translatethe logical file into a “physical file”, i.e. to find the different parts of the file (records) on thecorrect blocks (sectors, tracks) distributed over the physical device. This directoryadministers the free space of the device.

10.4 The MMC interface

10.4.1 Introduction

The Man Machine Communication (MMC) software is a part of the I/O System and providescommunication between supervising personnel (operators) and the exchange (see figure380). It forms a component of the interface between the man machine terminals (VisualDisplay Units, printers, ...) and the software application programs. The application programs

(users) perform the functions requested by operators and/or generate automatic reports.

Communication between an exchange and the operators is divided into two parts:

� dialogue Handling, or the command interface:

ORJs are entered via the terminals to request the desired functions. Responsesare generated by the MMC software to make the dialog. These responses are not theresult of the functions being performed, but are related to the initial input data.

� monologue Handling, or the report oriented interface:

Output messages like reports and alarms are generated automatically, either as aresult of a previously given ORJ (solicited report) or as an indication of events detectedwithin an exchange (unsolicited report). Each report or alarm is identified by a uniquenumber, the Report Reference Number (RRN).

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Figure 380 : Communication with A1000 S12

ALC

ATE

L 1000 S!2

FUNCTIONS

EVENTS

ALARMS

OPERATOR

ACTION

REACTION

LINE PRINTERMONOLOGUE

DIALOGUE

REPORT

SYSTEM 12

MASTER ALARM PANEL

10.4.2 MMC–dialogue–interface

The operator initiates a dialogue session by sending a ’BREAK’ to the device control of theIOS. The device control identifies the input device and prompts the operator for a password.When entered the password is not displayed on the screen.

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The authorization check looks for the password in a password list. There are two possibilitiesfor this list : the passwords are either stored as mnemonics (a password consists of up to 8characters and is taken as it is entered) or encrypted. In the second case a passwordconsists of at least 6 up to 12 characters and has to be encrypted before the list is accessed.The password must be unique in this list.

The password list consists of 999 possible passwords. To each password a set of command

areas is assigned. All acceptable commands are distributed to 128 different commandareas. Further the authorisation check controls a second list, which assigns a set ofcommand areas to all possible input devices. The combination of both gives the list ofcommands for which the operator with his password and input device is authorized.

If the password is found in the password list the IOS sends a dialogue header, containing theexchange name, date, time, day of week, the physical address of the input device and alogical password identification (internal password index as a pseudo–user–ID) back to theinput device and prompts for a command input. Otherwise the dialogue session isterminated with an error message.

Then the command input is checked to determine, whether the authorization is given for theactual session. A command list gives the responsible command area for all acceptablecommands. For all other inputs the session terminates with an error message.

To perform the syntax check and translation of the ASCII input into binary format, which isunderstandable for the system SW, the dialogue data is accessed. Each command area ishandled in one disk file. A directory of all dialogue files is written in the prologue file. Eachfile access is performed by the IOS file oriented interface. The MMC translation sends aprompt for all missing mandatory–parameters to the input device. The response of eachinput is taken from a response list. A command can have up to 63 parameters and severalarguments per parameter.

After the correct command input is completed, the job management creates an ORJ byperforming an entry in the actual joblist to administer the job. The entry consists of the jobsequence number (job counter, which is incremented by one for each new job), date, inputdevice, logical password, index and the process ID of the command handler process whichis called to perform the task initiated by the given command. The job sequence number,date, command reference number and the job state ’JOB SUBMITTED’ are displayed to theoperator.

After the translated command string is launched to the responsible application process thesemantic check is performed by the command handler (arguments valid). If no errors aredetected, the new job state ’RESULT DELAYED’ is updated in the job list and displayed onthe input device.

Beside this single command input procedure the MMC dialogue interface can handle batchfiles. Files, stored on disk or externally, containing a list of commands. The compounddialogue works through the batch file by performing the requested tasks sequentially. Theoperator decides if the dialogue should be aborted or continue in case of an unsuccessfuljob and where the results should be stored.

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Figure 381 : MMC interface of the IOS

operator

AuthorisationCheck

MMC–translation

Device

ControlLogging

Loggingtablesandfiles

jobmanagement

reportrouting

generalremoteI/O–itf

”user”(e.g. command

handler)

Log.devicelist

reportroutingtables

Passwordlist

DeviceCharacteristics

Device Status

MMC–tables& files

jobstatuslist

command

...

...

...

to whichoutput devicesshould the given report be sent ?

is the operatorwith his input deviceauthorised for the given command

state of all allrunning jobs

What is the actual

10.4.3 MMC–monologue–interface

The MMC–Monologue–Interface of the IOS performs all functions concerning the output of

reports to the desired devices. A report is a type of message launched in order to passinformation given Alcatel 1000 S12 to a human being. There are three types of report.

� Solicited reports are responses to operator requests. The report is defined by a certainReport Reference Number (RRN) depending on the triggering command and belongs tothe created ORJ specified by the Job Sequence Number (JSQ).

� Unsolicited reports are messages without an external trigger. Their JSQ is set to 0,because they are not ORJ triggered.

� Alarm reports are special unsolicited reports. They are treated with a higher priority andsignal the change of an alarm state (on/off) in the system.

All reports are routed via a general remote I/O interface in the control element of the sendinguser to the IOS in the standby PLCE. First report routing launches the binary reportmessage to the MMC translation, which is responsible for translating data into ASCII and

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bringing it into a specific layout, depending on the RRN. All report layouts are stored in theMMC monologue file on disk. The report is sent back to report routing in an easily readableformat for the operator.

The user sends an Output Set Identification with the report message to report routing forindividual distribution to several output devices, depending on the contents of the report.Each combination of an RRN and an Output Set ID is linked to a group (report group) ofmaximum 8 logical devices, which represent different output channels, with optionalalternatives such as fallback as defined in the device assignment list.

Additionally the report may, if specified in the routing tables, be sent back to the input device.Further, the operator can specify an individual output device for each command by means aspecial parameter.

If a desired output device is not available, the report routing queues the reports for lateroutput, depending on their priority.

A displayed report consists of a monologue header with the same contents as the dialogueheader of the triggering command, the JSQ, the result (successful or not), a repetition ofcommand and parameters, additional information about the result and the RRN. With theRRN the operator can find further information in the Manuals to interpret the report. The ORJis deleted in the job status list, after the output of the final report to all desired devices.

10.4.4 Logging

The Logging subsystem provides a logbook of the MMC interface. All inputs and outputs ofthe system SW via the dialogue or monologue interface can be stored in special files on thedisk. There are five different log types, which are handled separately:

– all inputs entered by the operator with his peripheral device;

– all commands accepted by the job management (with access rights and correctsyntax);

– all solicited reports;

– all unsolicited reports;

– all alarms.

For each type the Logging function can be switched on and the stored data can becontrolled and saved. Several search parameters exist to display the subsets of the loggeddata.

– log type;

– time and data slice;

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– input device;

– LPN;

– CRN or RRN;

– exchange identification.

Any combination of the search parameters is allowed. The found subset of logged data foraccept commands can be executed again. All commands which are selected by the operatorare translated into ASCII and stored in a temporary file, which is handled as a batch file.

10.5 Exchange administration

The IOS provides several functions, called I/O utilities, for the operator to install hisadministration environment, and to support the application SW with help functions.

A main task is to save the system SW periodically, so as to have an actual fallback in case ofa crash. There are two possibilities supported and described in detail by task procedures inthe Manuals depending on the destination backup media, which are optical disks ormagnetic tapes.

The amount of maximum 5000 files is divided into unchangeable files for the system loadpart, and changeable files for the data load part; referring to the file type stored in the filedescriptor block. The two parts can be saved separately.

The operator has to administrate the volumes of the changeable mass storage media(format, mount, etc.) for the backup generation. Further he can save logged data, chargingor statistic data individually. For this purpose file handling features are available. Single filesand the whole contents of mass storage media can be copied, and the file status and filedefinition can be controlled.

Most of the commands can be submitted with a time schedule for later execution. Start date,time of job execution and time period for periodically executed jobs can be specified. Theoperator may control the job status and schedule.

In addition he can influence the report routing tables to decide which output devices shoulddisplay a certain report identified by its RRN and Output set ID. The logical deviceassignment and the physical device characteristics are changeable and the device statuscan be supervised by MMC commands.

Another important task is to prevent the system from misuse. Therefore, commands areassigned to command areas, command areas to passwords and to input devices andpasswords to users (operators). Each device and each operator has an individualauthorization profile. Only commands belonging to specified tasks are accessible for theoperator, depending on his duties.

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The IOS utilities treat the system SW in a common way without referring to its telephonicapplications. They can be triggered by any program which needs help. General informationabout the SW version and all SW parts are available. Load and initialization procedures aresupported, and recovery actions are performed.

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11.ADMINISTRATION

11.1 Introduction

The Administration subsystem is one of the nine subsystems into which the A1000 S12software has been divided. It occupies the highest level in the A1000 S12 software where itis distributed within the different modules that make up the software.

Figure 382 : Subsystem interface

OPERATING SYSTEMAND DATABASE

CONTROL ELEMENTHARDWARE

TELEPHONICSUPPORT

ADMINISTRATION

MAINTENANCECALL HANDLING

TELEPHONICDEVICES

SWITCHINGNETWORK

(DSN)

PERIPHERALDEVICES

This subsystem provides the software necessary for the exchange operation, that is, theexecution and support of all operational functions. This software executes the exchangemeasurements and statistical functions including data collection and display and printout ofthe measurements taken. Furthermore, this administration software manages the storage ofthe measurements and other associated data on mass storage devices.

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This subsystem uses the other subsystems mentioned before to gather the data necessaryto accomplish its task.

The programs that make up the software of this subsystem are generally not critical in time.The majority of these programs are therefore stored on disk and copied into the overlayzones of the different CEs when required.

The Administration software is divided into the following areas:

– traffic performance and measurement collection;

– exchange management;

– network management administration;

– HW and SW extensions.

11.2 Traffic measurements collection and supervision

The A1000 S12 is capable of carrying out statistical and traffic measurements.

All main statistical events are continuously collected by the exchange software and they areused to update a great amount of software counters. These counters are used to provide allthe different types of measurements that can be requested.

Measurements are intended primarily to determine the trend of carried traffic volume and thegrade of service, to obtain warnings of abnormal conditions, to investigate temporaryabnormal traffic situations, etc.

The types of measurements performed by the administration software are related to theexchange type and customer requirements. These can be general statistics (e.g. number ofincoming terminating calls, number of hook–off events during a certain period), occupancymonitoring, call sampling (e.g. call recording on one specific call in every N), observation fordifferent types of calls, CE load and overload measurements, etc.

11.2.1 Measurements based on statistical counters

The statistical system is divided into two different levels in order to perform its functions:

� Report generation level. This level is the interface with the operator and is active onlywhen the operator so requires.

� Collection level. This level is always active. The data collected by this level is used bythe control level.

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Figure 383 : System statistics structure

REPORT

GENERATION

LEVEL

COLLECTION

LEVEL

ACTIVATION PERIODICAL

INFORMATION

DATA

REQUEST

IO

SUBYSTEM

OPERATIONS

AND

REPORTS

a. Collection level

The A1000 S12 system is continuously collecting data and updating counters. LocalData Collectors (LDCs) are used to collect statistical data, and a Central Data Collector(CDC) groups the data distributed among all the LDCs.

– Local Data Collector (LDC).

The statistical events are reported to the Local Data Collectors SW (LDCs) mainly bythe Call Handling subsystem. The LDCs update and manage the counters associated athose events. This software LDC and the counters are located in the SLDCTRAs.

– Central Data Collector (CDC).

Most LDC counters are periodically collected by the Central Data Collector SW (CDC)using a polling strategy. The Central Data Collector is located at a duplicated ADMCEor PLADMCE. These data are summed up and stored in a centralized database.

The number of seizures per trunk, for example, is stored in the SLDCTRA related to thespecific trunk, while the average number of seizures per trunk group is stored in theCDC. The counters are collected every five minutes for network management andtrunk monitoring functions and every fifteen minutes for general measurementfunctions.

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Figure 384 : Collection Level

PLADMCEor

ADMCE

SLDCTRA_1

SLDCTRA_1

SCALSV_1

SCALSV_1

LINE TCEs

LINE TCEs

TRUNK TCEs

TRUNK TCEs

LOCALDATA

COLLECTOR

CENTRALDATA

COLLECTOR

EVENTS

EVENTS

POLLING

b. Generation report level

As previously mentioned, the generation report level SW acts as an interface with theoperator and uses the collection level to provide statistical data.

The interrogation of counters is performed by the Administration SW, which has theinterface with the collection level, LDC or CDC, depending on the type ofmeasurement.

The exchange statistics can be requested by defining a complex time pattern (differentdays, different times, etc.). A schedule module is in charge of sending a message forthe different analysis periods. This message will start or stop the measurement.

It is possible for the operator to display the requested statistics at any time, obtainingdetailed information about the measuring plans under way.

This generation report level manages most of the system counters. It allows theindication of several entities and several objects for each entity, over which to take themeasurements, in a single request. It is possible to indicate, the precise moment tostart and stop the measurements, the period of the measurements, and the device onwhich the results will be output.

There may be several active requests at any given moment. The collection methodused the compatibility of each measurement. This is so because the method is alwayscumulative and the values are calculated from the difference between the value at themoment the measurement starts and at the moment it is given to the operator.

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Basically, this SW decodes the operator requests, it drives the starting and ending ofthe collection periods, collects the values of the corresponding counters from thecollection level, and formats the monologues containing the requested counter values.

Figure 385 : Report generation level

REPORTGENERATION

LEVEL

IO

SUBYSTEM

SCHEDULER

ADMINISTRATION

DISPLAY

MEASUREMENTS

LDC

CDC

Certain events are not collected by the usual statistical system because they havespecial characteristics. These are referred to the overload of the Control Elements.

These events are handled directly by the Operating System. A special FMM is incharge of these events. This FMM belongs to both levels, the collection level and thereport generation level, so it both updates counters it manages operator commandswhile being in charge of the corresponding output reports.

Two main counters are provided:

– number of times an overload is encountered;

– duration of the overload.

11.2.2 Call observation

The Alcatel 1000 S12 SW contains an observation function to obtain an evaluation of thequality of service performed by the exchange itself and the peripheral exchanges. Thisfunction is started by an operator request. The results are supplied in the exchange in theform of reports (VDU or printer).

Call observation in the Alcatel 1000 S12 involves three types of measurements:

� Signalling register

The measurements are performed on one selected trunk. Mainly, the signalinterchange between both exchanges through the trunk, the trunk identity, the servicecircuit identity and the time are recorded.

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This function can be applied to any type of signalling CAS or CCS –ISUP, TUP, etc..–.

� Call sampling

One out of every N calls of a certain type (national, international, etc.) is sampled. Thesample provides an estimation of the traffic in the exchange, and determine the gradeof service for the basic and the supplementary services.

� Single Line Observation

All events that occur on incoming calls from local subscribers or trunks are collected.The time at which each event occurs is also recorded.

The observation breaks down into three different phases: activation, collection, and output.

In the Activation phase , the SW modules in charge of managing the call observation areactivated by operator command. It is possible to start, modify or stop the call observationusing a set of ORJs directed to these two modules. When indicated by the generation reportSW, the Call Observation SW puts the lines or trunks in observation (or removes them fromthis state), notifying the Call Handling SW. This subsystem determines which call must besampled and starts the transmission of the events to the collection level SW.

In the event collection phase , the call handling events relating to the observation types arecollected at the time at which they occur.

Finally, in the output phase , the module in charge of this function receives a buffercontaining a set of observation data of a call. It carries out the translation, using a specificformat, to a binary file of the system. Upon operator request from a PC, the translation toASCII is performed and this information is stored on a PC disc.

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Figure 386 : Observation data collection

SRCSSLO

OPERATOR

PRINTERDISK

CALL HANDLING

UNPACK

ACTIVATION

PHASE

COLLECTION

PHASE

OUTPUT

PHASE

DATACOLLECTION

11.2.3 Supervision

The main objective of this function is to provide a permanent surveillance of the exchangeand the network performance.

The objects under observation are mainly:

� The exchange itself

� Control elements

� Single trunks

� Trunk groups

� Routes

� Service circuit types and modules

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� Analog & ISDN lines

� X25 links

� etc.

The supervision is based on the measurement subsystem. In fact a set of statistics countersare interrogated, processed and compared to some threshold values (which can be modifiedby MMC). The counter values are provided in an Nx5 minutes period.

Based on this action, it is possible to report that something may be wrong –adding indicatorsor ratios– and to activate or deactivate alarms. Sometimes automatic tests on some objectswhich are suspected of being faulty are triggered. If, after checking, the ’faulty’ condition isconfirmed, the object is set to unavailable until the cause has disappeared.

Some examples of analog line supervision are:

� Unavailability of lines. This function allows to supervise the relationship between theunavailable lines and the total lines. This feature can be activated for homogeneousgroups and for a specified time.

� Dial tone delay. If the dial tone delay exceeds an administrable threshold, the call isconsidered as delayed. If at least one delayed call is found, a report with the percentageof delays calls and the average dial tone delay will be output.

� etc.

11.3 Exchange management

The Exchange Management software handles operator requests to change the Semi–Permanent Data of the exchange.

The Semi–Permanent Data (SPD) define the configuration of the exchange in terms offeatures, facilities, and associated information, such as subscriber and trunk facilities,charging information, allocation of routes, etc. All these data are created in the softwareproduction phase and are held in the relation of the exchange database.

When some of these data have to be updated, the operator can use a set of ORJs which aretranslated, by the Administration software, into data modification commands executed by theData Base Management System.

All these ORJs are organized into homogeneous groups, mainly Subscriber, Routing, Prefix,and Charging administration.

11.3.1 Analogue and ISDN subscriber line administration

Some of the ORJs enable the exchange personnel to manage the data associated with thesubscriber (analogue and ISDN) lines. Allocation, changing and removing a subscriber’s

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class of service, class of line, as well as interrogation are possible. Also ORJs formanagement of the PABX Semi–Permanent Data are provided. Introduction and removal ofPABXs, updating and displaying of the PABX organization plan are available to the operator.

A set of commands, known as ’Handle Line’, have been developed to manage eitheranalogue or ISDN individual lines. Both of them, subscribers connected directly to the A1000S12 host exchange and subscribers connected remotely via a IRSU, are handled in a sameway. The identity of the subscriber is indicated by the Equipment Number (EN) , DirectoryNumber (DN) or even Multi Subscriber Number (MSN). The EN is commonly used whenthe DN has not yet been defined.

This set provides the following commands :

� ’Create’ allows the operator to introduce new subscribers into the system. No facilitiescan be introduced during the creation phase.

� ’Modify’ and ’Display’ allow to update or display the subscriber’s featuresand classes.

� ’Remove’ is used to remove or intercept the subscriber specified in the input.

Another set of commands, known as ’Handle PABX’, is used to create and maintain PABXrelated software data. The PABX can be linked to the system by means of analogue or ISDNlines, by Primary Rate Access (PRA), by digital trunks, or other combinations.

It is possible to create a new PABX plan in the system. The corresponding ORJ allows theadministration to set up the PABX layout and to define the main PABX features. Thesefeatures, e.g. : line/trunk group organization, search mechanism, etc., can be modified ordisplayed on the VDU. In addition part of the PABX or the whole PABX can be removed fromthe exchange.

On the other hand, the so called ’Complex facilities’ are managed by a set of commands thatallow the creation, modification, and removal of abbreviated dialling, Closed User Groups,ISDN Packet Switching, etc.

An example of this command area is the command used to display a subscriber. To executethis command only the DN or the EN is needed:

<DISPLAY–SUBSCR:DN = K’4995060;

When the command is entered, the job is submitted:

ÊÊSEQ=6807.920624 9002

COM=4296

JOB SUBMITTED 9000

RESULT FOLLOWS

This command causes all features and characteristics of the subscriber, both analogue orISDN, to be displayed:

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OTES5_N4_1_213 1992–06–24 15:03:04 WE

001 0130/0006/0003

SEQ=6807.920624 04263

SUBSCRIBER ADMINISTRATION

DISPLAY SUBSCR SUCCESSFUL

FINAL RESULT 1 –

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

EN PHYS (LOG)/ENICONC DN A/I MSNDFLT GDN

H’30 (H’6C0 ) & 93 04995060 A

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

BCAUTH : SPEECH AUD_3_1K

CHARGING METERS : 0

SERVICES :

SUBGRP : 1

SUBSIG : CBSET

SUBCTRL : CFWDBSUB CFWDFIXA CFWDNOR

CFWDUVAR

CFWD : CFWDUVAR 04992345 ACTIVE

COL : NORMSUB

BLNGLEV : 0

MAXCFWD : CFWDU 1

CFWDFIXA 1

CFWDBSUB 1

CFWDNOR 1

DEFLECT 1

LAST REPORT NO = 04263

11.3.2 Routing administration

The purpose of routing administration is to maintain the routing info in an exchange bymeans of ORJs. The basic routing info in an exchange is:

� Trunk: The necessary elements to branch one user channel between two exchanges.

� Trunkgroup:A number of trunks between two end points, sharing the same facilities(signalling, direction, etc).

� Route: All trunkgroups directly connecting two points.

http://dms.bel.alcatel.be/secure/cgi-bin/osform/dms?osform_template=calldoc.oft&act=HLINK&code=_049/_92/_345/_acti/_ve____.pl

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� Routeblock: A number of routes which can be selected to reach an indicated destination(prefix). In each routeblock there is one preferred route which is called primary route. Theother routes in the same routeblock are called alternative routes. These routes arechosen only in case of congestion or unavailability of the primary route.

The main SPD of the trunks are:

– – the terminal number of the trunk

– the identity of the trunkgroup the trunk to which

– the control element identity

– the trunk state

– particular features (semi–permanent connection, etc.)

Figure 387 : Routing basic concepts

A

B

E

C

D

AnnouncementCentre

TRKGR ADTRKGR DE

TRKGR AC

TRKGR AB1

TRKGR AB2

TRKGR BC

TRKGR CE

TRKGR BE

RouteBlock AB

RouteBlock AE

Route AB SubscriberSubscriber

Subscriber

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Figure 388 : Relation between trunks

RouteBlock AB

Route AB

TrkGrp AB1

Route AC

TrkGrp AB2 TrkGrp AC

Trunk 1 Trunk 2 Trunk 1 Trunk 2 Trunk 1 Trunk 2

A trunk has to be seized by the operator in order to update its associated data. When theoperation is executed successfully, no more calls are allowed on the trunks. The trunks canbe specified with their terminal control element identity and terminal number or with theidentity of the trunkgroup they belong and the trunk sequence number within the trunkgroup.

Once a trunk is seized, the modify and display commands can be used by the operator tochange or/and display the call handling related data of this trunk.

The trunk can then be released from operations. After this command is executed, only callsor trunk test calls are allowed and data manipulations are no longer possible.

Another possibility is to move trunks. This command performs the reallocation of trunks fromone trunkgroup to another. In other words, this command functionally performs a decreasein the call handling capability through a trunkgroup, followed by an increase on the extendedtrunkgroup. The operator has to change the GLS of the TCE involved, if the new signallingtype of the trunks is not covered by the currently loaded GLS.

The trunkgroups can be divided into two main groups: the incoming and the outgoing ones.For these trunkgroups some of the associated Semi–Permanent Data are:

– – the trunkgroup identity

– the list of the associated trunks

– the signalling type

– the identity of the route to which the trunkgroup belongs

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– the reference trunkgroup for DID

– the preselection digits

– etc..

as well as the nature of address and destination point code for the N7 trunks.

Taking into account all these parameters, it is possible to create or remove trunkgroup, ormodify the data of an existing one. The data can also be displayed. Removal of a trunkgroupis only allowed if it is not allocated to a routeblock and does not contain trunks.

The commands to reduce or extend trunkgroups are used to decrease or increase thenumber of trunks within a trunkgroup. The command creates the relationship between thetrunk terminal control element identity and the terminal number at one side, and thetrunkgroup identity, the trunk sequence number and the trunk terminal control elementsequence number within the trunkgroup at the other side. It also copies the trunk relateddata defined at the trunkgroup level to the trunk level. The operator has to change the GLSof the TCE involved, if the new signalling type of the trunks is not covered by the currentlyloaded GLS.

In addition, the route administration software provides a set of tools to handle all the datarelated to the routes and the routeblocks. The main commands are create, modify, remove,display, etc..

When a route is created, it is included in the DataBase. The route number will be generatedby the ORJ for internal use. Once the route exists, a series of trunkgroup can be allocated toit, using the modify command. This command can also be used to change the status of theroute (in–service, out–of–service, etc.).

Analogue features exist for the routeblocks. The create feature is used to introduce a newrouteblock, and subsequently, a new node in the routing–plan. This routeblock will later beused by the Prefix Administration ORJs to connect it to a prefix. The bearer and thesignalling dependencies have to be specified by the introduced subroute–block (ahierarchical set of subroutes). The trunkgroups are sorted into subroutes which are selectedaccording to their priority: first the primary subroute, then the first alternative one, and so on.

11.3.3 Prefix administration

In an exchange, a number of specific call handling tasks have to be performed during callset–up and call release. These tasks can be charging, signalling and destination related(e.g. local or outgoing call, numbering type, signalling type). The decision on how to performthese tasks is based on three parameters: the originator of the call (subscriber ortrunkgroup), the destination of the call (prefix), and the type of call (normal, coinbox, etc.).

This information is used inside PATED. With these input parameters, PATED will be able toselect the specific tasks for every call. If the call set–up cannot proceed, the underlying

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cause is presented to the call service subsystem (=CAUSE) and a specific task will beperformed to release the call set–up in a defined way.

Most of the information related to prefix analysis is in Semi–Permanent Data form. Some ofthe data is administration dependent and a lot more data is exchange dependent. By meansof man machine communication, the operator can get access to all of these data.

The main key parameters used to handle the PATED data are:

� The source code: A number reference to the type of originator of the call in theexchange.

� The nature of address: Only relevant for a call on an incoming trunk. It indicates wherethe call originated.

� The Prefix: Used in the exchange to route the call.

� Type of call: Indicates the calling party category (normal, coinbox, etc.).

With these input parameters it is possible to find a specific origin and destination of thedifferent tasks. All this data can be retrieved by means of the display feature. For instance, itis possible to display, for a given prefix, an overview of the input parameters and next theinformation of every digit of the prefix. This result may be a CPX, a Cause, and the numberof digits that are still required.

It is, of course, also possible to create a new prefix. When you create a prefix you have todefine all the necessary data for that prefix. You can also modify a prefix data profile.

11.3.4 Charging administration

The charging administration of the A1000 S12 exchange provides tools to change thecharging calendar, the charging scale, the tariff, the charge accounting (revenue sharingbetween operating companies), etc.

To define the charging information. such as method, rate, number of pulses, etc., thecharging programs require four codes:

� The originating code for charging: This code is derived form the source code and thenature of address.

� The destination code for charging: This parameter is used to group destinations thatare considered as a unique destination by the charging system. It is derived from thedialled prefix.

� The type of call: This code is retrieved from the class of service.

� The calendar: Up to eight calendar types can be defined. This calendar gives a categoryfor every day: workday, weekend day, holiday, and special day.

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The operator has some commands to handle charging data. It is possible to display theprefix tasks for charging to a destination or to a supplementary service, as well as to modifythis data. Also, the different types of calendar, the charging tariff, the rate, the number ofpulses and the charging method used for each tariff group and their correspondingswitch–over times, can be displayed or modified.

Example : To display the charging calendar, with two possible parameters, either the weekcalendar or the year one, the execution of the command would be as follows:

ÊÊ<DISPLAY–CHARGING–CALENDAR:WEEKCAL ,TABLE=2;

SEQ=6817.920624 9002

COM=0752

JOB SUBMITTED 9000

RESULT FOLLOWS

Once the job is submitted, the charging assigned to every day in the week is shown:

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OTES5_N4_1_213 1992–06–24 15:28:20 WE

001 0130/0006/0003

SEQ=6817.920624 00766

AREA=CHARGING ADMINISTRATION

DISPLAY CHARGING CALENDAR SUCCESSFUL

FINAL RESULT 1 –

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

OPTION = BASIC WEEK CALENDAR

CALENTYP SU MO TU WE TH FR SA TABLE

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

















–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

LAST REPORT NO = 00766

11.4 Network management

The reason for implementing a Network Management system is to ensure to efficientoperation and to maximize the traffic handling capacity of the network during periods oftraffic overload.

Overload occurs when there are insufficient traffic handling resources in the network tohandle the incoming traffic. Causes of overload can be switching or transmission equipmentfailures, natural disasters, family–oriented holidays, underestimated growth in demand forservices, etc.

Overload has an undesirable effect on an uncontrolled network. When traffic is low and theavailable quantities of all the various types of resources needed to set up any call aresufficient to handle the traffic, all offered traffic is carried out. When traffic increases, the

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resources needed to complete some calls become unavailable and these calls are blocked.Since most of the calls are immediately (or soon) reattempted, further demands are placedon the network’s resources. The result is that, due to deadlocks, above some higher level ofoffered traffic, a congested network without Network Management begins to carry less trafficthan at lower traffic levels.

Moreover, calls initiated at the (usually) less congested periphery of the network in generalencounter congestion near the middle, after having already utilized several stages ofintermediate resources which therefore cannot be utilized by other traffic. Under conditionsof extreme overload, this congestion can result in the inability to complete any call in thenetwork.

The ideal action of the Network Management would to cause a reduction in the offered trafficto a point just below the critical level at which deadlocks begin to occur, thereby maximizingthe traffic handling capacity of the overloaded network. This can be accomplished byseveral methods, e.g.: cancelling offered traffic at the periphery of the network, delaying orpreventing reattempts on incomplete calls, minimizing the resources used to set up andcomplete the calls by restricting alternately routed call attempts, etc.

The Network Management in the A1000 S12 provides the facilities necessary for thenetwork managers to maintain the efficient operation of the network during periods of trafficoverload. First, it provides tools which enable network managers to obtain timely networkperformance data. Second, it provides tools that can be used to modify the network trafficflow in order to reduce overload and thus increase the number of calls that can becompleted by the network.

Since overload conditions cannot be predicted and do not affect the different equipmentswithin the network to the same extent, the Network Management system must be flexible,resilient, and for most of its actions rely on the timely application of the experience andwisdom of the network managers controlling it.

The strategy for Network Management in the A1000 S12 is based on the use of centralizedintelligence: the Network Service Centre or a particular administration dependent centre,which communicates with the depending exchanges. These exchanges give the necessaryindicators to the NSC and react to the requests received from the NSC.

Conclusion: Network Management can be defined as the whole of operations intended toexploit an existing network with maximum efficiency, and to restore normal operation whenthe proper working has for some reason been disturbed. Network Management can also beused as a planning tool to avoid network problems in the future.

The main objectives of the Network Management are to provide real time response tounexpected network conditions and pre–planned actions to deal with regularly recurring andpredictable conditions, as well as to work out methods to restore service after an overload.

In order to carry out the above mentioned objectives some indicators have to be provided.These indicators are related to interesting phenomena from a network management point of

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view, e.g.: indicator of traffic that has a low probability to reach a destination, trunkoccupancy indicators, exchange overload indicator (i.e. too many calls not accepted by thesystem), etc.

Based on these indicators, certain actions can be initiated in the exchange:

� actions which affect only the internal behaviour of the exchange: exchange load control;

� actions which have an influence in the network: network load control.

11.4.1 Destination controls

Destination controls are used to limit traffic which has a small probability of reaching aspecified destination.

Some of the implemented controls are: Code Blocking, Hard–To–Reach, Explosive TrafficControl and Call Gapping.

a. Code blocking

Code blocking control can be used to block traffic towards destination codes, whichhave a small chance of being completed. This capability is used to limit traffic surges toa destination. It can also be used to limit traffic early in the network to an office or codethat is partially or completely out–of–service, thereby conserving network resourcesand preventing local congestion from being propagated through the network.

A code blocking destination can be defined as a dialled digit string from 2 to 12 digits inlength. Calls can be restricted to certain areas, specific exchanges, or even individualsubscribers, and these calls are directed to a specific announcement. The cancellationof calls is done on a percentage basis.

Figure 389 : Code Blocking

PSTN

A1000 S12

Calling

Subscribers

CALLS ATTEMPTSTO A DESTINATION

– TELEPHONE AREA

– AN EXCHANGE

– INDIVIDUALSUBSCRIBERS

IS CODE BLOCKINGCONTROL TRIGGERED?

YES

HANDLE A PERCENTAGEOF CALLS (X%)

CANCEL A PERCENTAGEOF CALLS (100–X%)

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b. Hard–to–reach

Traffic which has a low probability of completion is named hard–to–reach. Since certaindestinations may become hard–to–reach only at certain times, especially under hightraffic conditions, it is desirable to block calls only during the time they are experiencingcongestion. Hard–to–reach analysis is used to determine when the relevantdestinations are congested. The analysis also determines when the congestion hasbeen relieved. Since the exchange does not automatically determine whichdestinations are involved (or are potentially hard–to–reach), this control can beconsidered as semi–automatic.

To determine whether a destination code is hard–to–reach four thresholds are used,namely: the lower & the upper ’call attempts’ thresholds, and the lower & the upper’answer/bid ratio’ thresholds. When the hard–to–reach analysis is triggered, thesethresholds are compared to the actual real–time call attempts and call completionmeasurement data counters. To establish the hard–to–reach condition on a destination,the number of call attempts towards the destination during the previous data–collectionperiod must exceed the upper ’call attempt’ threshold, and the collected answer/bidratio towards the destination must be less than the lower ’answer/bid ratio’ threshold.

The hard–to–reach blocking is removed from the destination when one of the followingconditions is met: the number of call attempts towards the destination during theprevious data collection period falls below the lower ’call attempts’ threshold, or the callcompletion ratio towards the destination during the previous data collection periodexceeds the upper ’answer/bid ratio’ threshold.

A hard–to–reach destination can be also defined as any dialled string from 2 to 12digits in length. Calls can be restricted to certain areas, specific exchanges, or evenindividual subscribers.

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Figure 390 : Hard–to–reach control

PSTN

A1000 S12

Calling

Subscribers

CALL ATTEMPTSTO A DESTINATION

– TELEPHONE AREA

– AN EXCHANGE


HARD–TO–REACH FLAG SET?

YES

HANDLE A PERCENTAGEOF CALLS (X%)

CANCEL A PERCENTAGEOF CALLS (100–X%)

c. Explosive traffic control

Explosive traffic control is used to avoid that calls to certain prefixes seize all resources(trunks).

The number of call attempts towards a certain prefix over a certain time period iscompared with a threshold, namely the maximum allowed number of call attempts. Ifthe maximum number of allowed call attempts determined to be towards a certainprefix is not reached then the actual number of call attempts is incremented and the callis handled. If, however, the actual number of call attempts towards that prefix is equalto the maximum allowed number of call attempts, then the call is cancelled and anannouncement is returned. After a timeout, a value is subtracted from the actualnumber of call attempts.

Because the PATED processors handle the traffic in load sharing, the maximumnumber of call attempts specified by the operator is proportionate part of the maximumvalue of the complete exchange.

An Explosive Traffic Control destination can be defined as a dialled digit string from 2 to12, so that calls can be restricted to certain areas, specific exchanges, or evenindividual subscribers.

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Figure 391 : Explosive Traffic control

PSTN

A1000 S12

Subscribers

CALLS ATTEMPTTO A DESTINATION

– TELEPHONE AREA

– AN EXCHANGE


IS THE NUMBER OF CALL ATTEMPTS GREATER THAN A THRESHOLD?

YES

CANCEL THE CALL

d. Call gapping

This control limits the number of call attempts routed to the specified destination over aparticular period of time. The affected traffic will be routed to a special announcement.

The call attempts are treated by different PATED processors (load sharing). Therefore,the Call Gapping control will be given to one processor at a time. This requires ascheduling of the PATED processors to accept the call attempts for destinations underCall Gapping control.

During a defined period of time a PATED can be open or closed. The open period, alsocalled Gap Time, is given by the operator. This Gap Time multiplied by the number ofprocessors will be the Gap Cycle time.

There are several possibilities for Call Gapping. The first defines that a call will only beaccepted when it is the first call in an open period. The following call attempts in thesame open period and the call attempts in a closed period will be rejected and routed toan announcement. Another possibility, which is used when traffic is low, defines that acall will be accepted when it is the first call in an open period and that a call attempt in aclosed period will be accepted, when there was no call during the previous open period.In all other cases the call is rejected and routed to an announcement.

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Figure 392 : Call Gapping control

PSTN

A1000 S12

Subscribers

CALLS ATTEMPTTO A DESTINATION

– TELEPHONE AREA

– AN EXCHANGE


IS THE FIRST ATTEMPTIN AN OPEN PERIOD?

NO

CANCEL THE CALL

11.4.2 Routing controls

As explained before, in the ’Trunk Search’ chapter, the interconnections between exchangesare organized as routeblocks, routes, trunkgroups, and trunks. Some tables belong to theTrunk Resources Management software used to carry out the selection of a trunk for theoutgoing calls. These data can be modified by Network Management tools to avoid overloador blocking of trunks, routes, or routeblocks.

The following figure shows an environment of exchange interconnections which will be usedas an example. The exchanges are A (local), B (local and transit), C (transit), D (transit andannouncement centre), and E (local). The different trunkgroups among them can be seen onthe figure. Trunkgroups AB1 and AB2 form route AB, trunkgroup AC forms route AC, and soon. Routes AB and AC form routeblock AB, route AD and route AC form routeblock AE, andso on.

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Figure 393 : Network environment

A

B

E

C

D

AnnouncementCenter

TRKGR DETRKGR AD

TRKGR AC

TRKGR AB1

TRKGR AB2

TRKGR BC

TRKGR CE

TRKGR BE

RouteBlock AB

RouteBlock AE

Route AB SubscriberSubscriber

Subscriber

The trunk search scheme to reach a subscriber from exchange A to B and to E, is asfollows:

Figure 394 : Routeblock AB

Route AB

RouteBlock AB

Route AC

TrkGrp AB1 TrkGrp AB2 TrkGrp AC

Trunk 1 Trunk 2 Trunk 1 Trunk 2 Trunk 1 Trunk 2

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Figure 395 : Routeblock AE

RouteBlock AE

Route AC Route AD

TrkGrp AD

Trunk 1 Trunk 2

TrkGrp AC

Trunk 3Trunk 1 Trunk 2

a. Routeblock controls

This network management control is related to a routeblock. Two types of control areprovided: Cancel Alternative Routing and Temporary Alternative Routing.

The cancel ’alternative routing’ control prevents traffic towards a destination fromoverflowing from the high usage primary route to alternate routes after a fixed positionin the sequential routing plan. It has a restrictive effect because it prevents the seizingof trunks from a certain point during the selection of a route in a routeblock.

Taking the previous figure as example, route AC is both the primary route for routeblockAE and the alternative route for routeblock AB. If that route is congested by theoverflow of calls coming from the route AB, it could be necessary to cancel all the callscoming from AB to increase the number of successful calls to exchange E. This ismade possibile by the appropriate operator command.

On the other hand, the temporary alternative routing redirects traffic from congestedroutes to other routes not normally available which have idle capacity at the time. Atemporary alternative routing consists of a list of different route alternatives.

In our example, although route AD is not included in routeblock AB, it may benecessary to modify the alternative routeblock list to provide an alternative temporarypath to the calls from A to B: the A–D–E–B path. In this particular scenario, loops wouldprobably be created between exchange A and D.

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b. Route controls

Route controls are used to limit traffic to a specified route or to expand routing withinthe normal in–chain routes during congestion periods.

Some types of manual route controls are implemented to regulate the maximum callrate to keep the network at peak performance during periods of overload: ’cancel–to’,’cancel–from’, ’skip’ and ’announcement’ controls.

’Cancel–to’ control is used to deny access to a route. Traffic is cancelled and directedto a specific announcement. Calls are cancelled on a percentage basis from 0% to100%, in steps of 1%. Still following the figure example, when trunkgroups AB1 andAB2 are congested, the ’Cancel–to’ operator command can be used to cancel apercentage of calls trying to reach route AB.

’Cancel–from’ control is used to deny access from a route which would normallyoverflow to an alternate route. Overflow traffic is canceled and directed to a specificannouncement, on a percentage basis. In our example, in case of congestion onalternative route AC of routeblock AB, the operator can deny the overflow of callscoming from route AB. The command ’Cancel–from’ cancels a percentage of thesecalls.

’Skip’ control is used to force traffic to the next in–chain route. Calls are skipped on apercentage basis.

’Announcement’ control is used on a final in–chain route to alter the normal recordedannouncement. This control may be used, for example, to advise callers to postponereattempts (especially of non–critical calls), until a later time, rather than rediallingimmediately.

c. Trunkgroup controls

Trunkgroup controls are used to limit traffic to a specified trunkgroup to expand routingwithin the normal in–chain trunkgroups during times of congestion. Several trunkgroupcontrols are implemented to regulate the maximum call rate to keep the network atpeak performance during periods of overload.

’Cancel–to’ control is used to deny access to a trunkgroup. ’Cancel–from’ control isused to deny access from a trunkgroup which would normally overflow to an alternateone. ’Skip’ control is used to force traffic to the next in–chain trunkgroup.’Announcement’ control is used on a final in–chain trunkgroup to alter the normalrecorded announcement.

’Reservation’ control is used to regulate the traffic flow on trunkgroups by reserving anumber of trunks for certain types of traffic. The affected traffic is skipped to the nextavailable trunkgroup or cancelled if no alternate trunkgroups are available. The trafficcategory is defined as a function of the origin and the destination, the type of call, thehard–to–reach status, the bearer capability, etc..

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11.4.3 Machine congestion analysis

In addition to network overloads due to unavailability of trunks, digital exchange overloadsdue to excess demands on internal resources (receivers, senders, processor time, memory,data bus capacity, etc.) can occur.

The functions, collectively titled Machine Congestion Analysis, are performed in the A1000S12 exchanges in order to implement dynamic overload control within the telephonenetwork. Machine Congestion Analysis functionality requires cooperation with the networkmanagement centre to which this exchange is connected. A machine congestion report issent to the network manager so that he can perform the necessary manual controls to solvethe overload problem in a certain exchange. In a centralized point, the operator can betterestimate the consequences of his actions on the network because he has a completeoverview of the network in the NSC.

For purposes of dynamic overload control, four levels of machine congestion are defined: nosystem overload, moderate system overload, severe system congestion, and completeinability of the exchange to handle incoming and transit traffic.

11.5 Extensions

This part of the administration software controls all operator requests to perform equipmentextensions in the existing on–line environment of the A1000 S12 exchange. The mainextension objectives are to increase the traffic capacity of an exchange, to add new facilities,or to adapt the exchange to network extensions.

Hardware extensions add more hardware modules to an exchange as well as thecorresponding non CE hardware required as a result of their addition (e.g. DSN, clock &tone distribution, etc). The main steps to be followed are as follows : updating the databaserelations to describe the new hardware configuration, modifying of the hardwareconfiguration by installing the new modules, testing this hardware, and starting up (on–line)those modules.

Software extensions are used to add new features to an exchange, to enhance the existingfeatures or to add a new software package (i.e. to support the above hardware extensions).This procedure involves the addition or the replacement of programs and data in some or allof the control elements.

The system start–up is developed as mentioned in the previous part of the document(’System– Start–Up’ and ’Warm–Start–Up’).

The A1000 S12 extension strategy is subject to a number of requirements. Thus, there shallbe no significant interference with normal exchange operation. This implies that call handlingcapability shall be maintained, that the loss of calls in the set–up phase or conversationphase shall not exceed the number of calls lost during normal maintenance activities, and

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that the system availability requirements shall be met. In every step of the extension,however, the system must be able to roll back to the original configuration.

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ANNEX A : LIST OF ABBREVIATIONS

A

ABS Alternate Billing Services

AC Alarm Control

ACE Auxiliary Control Element

ACM Address Complete Message

AFF AMA File Formatter

AFFC AMA File Formatter Control

ALCN Analogue Line Circuit type N

ALCP Analogue Line Circuit type P

AMA Automatic Message Accounting

AMEA Additional Memory Board (DIAM)

ANC Answer with Charging

AOC Advice Of Charge

A&P Administration Support and Peripherals Module

ARTA Auxiliary Resource TCE Allocator

ARU Automatic Recording Unit

ASAC Administration System ACE

ASCII American Standard Code of Information Interchange

ASM Analogue Subscriber Module

B

BA Basic Access

BC Bearer Capability

BCG Business Communication Group

BCGRM Business Communication Group Resource Manager

BIDH Binary Interface Device Handler

BPA Backpanel

BS Basic Service

BSN Backward Sequence Number

BUT Backup Tape

BUTG Backup Tape Generator

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C

CACO Call Control

CAE Customer Application Engineering

CALC Control and Alarm PBA type C

CAS Channel Associated Signalling

CB Clear Backward

CCBS Call Completion to Busy Subscriber

CCITT International Telegraph and Telephone Consultative Comittee

CCLA Central Clock Advanced

CCLD Central Clock Distribution

CCNR Call Completion on No Reply

CCS Common Channel Signalling

CD Call Deflection

CDC Central Data Collector

CDE Customer Design Engineering

CDM Compound Dialogue Manager

CE Control Element

CFB Call Forwarding on Busy

CFFA Call Forwarding to Fixed Announcement

CFNR Call Forwarding on No Reply

CFU Call Forwarding Unconditional

CGC Charge Generation Control

CH Cluster Handler

CHAN Charging Analysis

CHIR Charging Information Request

CIC Circuit Identification Code

CLF Clear Forward

CLIP Calling Line Identification Presentation

CLIR Calling Line Identification Restriction

CLMA Central Alarm PBA type A

CLTD Clock and Tones Distribution

COL Class Of Line

COLP Connected Line Presentation

COLR Connected Line Restriction

CPC Calling Party Category

CPU Central Processing Unit

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CPX Condensed Prefix

CRC Cyclic Redundancy Check

CRM Charge Recording Manager

CSAC Charging System ACE

CSCO Charge Scale Change Over

CTCE Clock and Tones CE

CTLE Control Element SBL

CTM Clock and Tone Module

CUG Closed User Group

CW Call Waiting

D

DAHU Device Anomaly Handling Utility

DASSIGN Device Assignment relation

DB Database

DBCS DataBase Control System

DBSS DataBase Security System

DBU Disk Backup Utility

DDDG Dynamic Data Distribution Group

DDI Direct Dialling In

DDM Dynamic Data Manager

DH Device Handler

DIAA Digital Integrated Announcement PBA type A

DIAM Digital Integrated Announcement Module

DIL Digital Interface Limited

DK Data key

DLM DataLink Module

DLP Data Load Partition

DLS Data Load Segment

DLT Data Load Tape

DMCA Direct Memory Controller type A

DN Directory Number

DNE Directory Number Equivalent

DNEH Directory Number Equivalent Hundred

DNET Directory Number Equivalent Thousand

DOR Division Of Revenue

DORC Division Of Revenue Collector

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DORO Division Of Revenue Output

DPC Destination Point Code

DPLF Defense Pair Load Failure

DPTC Dual Processor Terminal Controller

DSDR Device Status Disk Recovery

DSE Digital Switching Element

DSGA Digital Signal Generator type A

DSN Digital Switching Network

DSP Digital Signal Processor

DSPA Digital Signal Processor PBA type A

DT Dial Tone

DT Diagnostic Test

DTCL Digital Trunk Common Logic

DTM Digital Trunk Module

DTMF Dual Tone Multi Frequency

DTRF Digital Trunk PBA type F

DTRH Digital Trunk PBA type H

DTRI Digital Trunk PBA type I

DTUA Digital Trunk Unit PBA type A

E

EBCDIC Extended Binary Coded Decimal Interchange Code

ECMA 13 EUROPEAN Computer Manufactures AssociationStandard 13

EDPC Electronic Data Processing Centre

EF External Fault

EOP End Of Packet

ETSI Eurpean Telecommunications Standards Institute

EQAWL Equipment Allowed

F

FBK Fallback

FCS Frame Check Sequence

FCU File Comparison Utility

FD File Directory

FDB File Descriptor Block

FDBM File Descriptor Block Maintenance Utility

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FDT File Descriptor Table

FDTA File Descriptor Table Administrator

FISU Fill In Signal Unit

FIT Faulty, but In Traffic

FLT Faulty

FMM Finite Message Machine

FSM Finite State Machine

FSN Forward Sequence Number

FW Firmware

G

GD Ground Detection

GDN General Directory Number

GIOR General I/O Remote

GIOUTY General I/O Utility

GLS Generic Load Segment

GLSC GLS code

GOS Generic Overlay Segment

GSM Generic Segment Module

H

HCCM High Performance Common Channel Module

HDB3 High–Density Bipolar Excess 3

HDLC High Level Data Link Control

HIAU Hardinit Audit Utility

HLC High Layer Compatibility

HM Home Meter

HSB High Speed Bus

HSCB High Speed Cluster Bus

HW Hardware

I

IAM Initial Address Message

ICB Interrupt Control Block

ICLP Internal Connectionless Protocol

ID Identification

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IDC Intermediate Data Collector

IDN Individual Directory Number

ILC ISDN Link Controller

I/O Input/Output

IOC Input/Output Control

IOS Input/Output System

IPABX ISDN Private Automatic Branch Exchange

IPP Internal Packet Protocol

IPTM Integrated Packet Trunk Module

IRIM ISDN RSU Interface Module

IRSU ISDN Remote Subscriber Unit

ISDN Integrated Services Digital Network

ISM ISDN Subscriber Module

ISTA ISDN Subscriber Termination PBA A

ISTB ISDN Subscriber Termination PBA B

ISUP ISDN User Part

IT In Traffic

ITM ISDN Trunk Module

IW Interworking

J

JSQ Job Sequence Number

L

LAPB Link Access Procedure Balanced

LAPD Link Access Procedure in D–channel

LCACO Line Call Control

LCE Logical Control Element

LCE–ID Logical Control Element Identity

LCG Local Charge Generator

LCS Local Charge Synchroniser

LDC Local Data Collector

LED Light Emitting Diode

LH Line Hunting

LI Length Indicator

LLC Low Layer Compatibility

LPFA Line Power Feed type A

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LSB Low Speed Bus

LSI Large Scale Integration

LSIF Local Subscriber Identification

LSSG Load Sharing SubGroup

LTL Local Tax Layouter

M

MAC Monitor Access

MCC Metering Counts Collector

MCI Malicious Call Identification

MCUA Module Control Unit type A

MCUB Module Control Unit type B

MDF Main Distribution Frame

MF Multi Frequency

MH Message Handler

MIM Mobile Interworking Module

MIO Multidrop Information Octet

MIRB Modem Interface and Rate Adaptation PBA type B

MMB Multi Master Bus

MMC Man Machine Communication

MMCA Man Machine Controller type A

MMCH MMC Channel

MMCM MMC Maintenance

MMT Man Machine Translation

MONI MPTMON CE

MPA Master Panel for Alarms

MPM Maintenance and Peripheral Module

MPTMON Multi Processor Test Monitor

MSAC Measurement System ACE

MSG Message

MSM Mixed Subscriber Module

MSN Multiple Subscriber Number

MTP Message Transfer Part

MTTR Mean Time To Repair

MTU Magnetic Tape Unit

MTUF Magnetic Tape Unit Formatter

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N

NDUB Network Defined User Busy

NEQ Not Equipped

NMI Non Maskable Interrupt

NPI Numbering Plan Indicator

NSC Network Service Center

O

OBC On Board Controller

OBCI On Board Controller Interface

OCB Overlay Control Block

OD Optical Disk

ODK Optical Disk

OLCOS Originating Line Class Of Service

OMB Output Meter Block

OMUP Operations and Maintenance User Part

OPC Originating Point Code

OPR Operator Out of Service

ORJ Operator Requested Job

OS Operating System

OSI Open Systems Interconnection

OSN Operating System Nucleus

P

PABX Private Automatic Branch Exchange

PARM Private Access Resource Manager

PATED Prefix Analysis & Task Element Definition

PB Push Button

PBA Printed Board Assembly

PBR Push Button Receiver

PBX Private Branche Exchange

PC Personal Computer

PCM Pulse Code Modulation

PD Peripheral Device

PERI Input/Output Device

PEQ Partially Equipped

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P&L Peripheral and Load Module

PLCE Peripheral and Load Control Element

PLS Patch Load Segment

PNP Private Numbering Plan

PRA Primary Rate Access

PSM Packet Switching Module

PSN Private Switching Network

PSTN Public Switched Telephone Network

PTCE Peripheral Terminal CE

PTN Physical Terminal Number

Q

QRC Queue Ram Controller

QS Queue Service

R

RAL Rack Alarm

RBL Repair–Block

RC Ringing Current

RCCA Reference Clock Control type A

RCLK Rack Clock

RIT Replaceable Item

RLG Release Guard

RLMC Rack Alarm PBA type C

RNGF Ring PBA type F

ROM Read Only Memory

RRAM Remote Report and Alarm Module

RRN Report Reference Number

RSU Remote Subscriber Unit

RT Ringing Tone

RTSH Report and Task Supervision Handler

RTSU Remote Terminal SubUnit

RUWA Relation User Work Area

S

SABME Set Asynchronous Balanced Mode Extended

SACE System ACE

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SAPI Service Access Point Identifier

SBL Security Block

SCALSV Subscriber Call Services ACE

SCB Simplified Conference Bridge

SCDH Service Circuit Device Handler

SCM Service Circuit Module

SCSI Small Computer System Interface

SI Service Indicator

SIG Signalling

SKR System Kernel Release

SLP System Load Partition

SLS Signalling Link Selection

SLT System Load Tape

SLTA Signalling Link Termination type A

SOS Software Out Of Service

SPATA Speech & Data protocol

SSA Small Stand Alone

SSF Sub Service Field

SSM System Support Machine

SSP Service Switching Point

STAT Statistic data

STP Signalling Transfer Point

SW Software

T

TA Terminal Adaptor

TACB Transaction Control Block

TAU Test Access Unit

TAUC Test Access Unit type C

TAX Taxation data

TAXUP Taxation User Part

TCACO Trunk Call Control

TCE Terminal Control Element

TDM Time Division Multiplexed

TED Task Element Definition

TEI Terminal Endpoint Identifier

TEL Telephonic Devices

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TERA/I Terminal Interface type A/I

TI Terminal Interface

TKG Trunk Group

TL Task List

TLCOS Terminating Line Class Of Service

TMIA Transmission and Multidrop Interface type A

TOC Type Of Call

TOD Time Of Day

TP Task Procedure

TRA Trunk Resource Allocator

TRAC Trunk Access Circuit

TRC Trunk Request Coordinator

TREX Training Exchange

TRM Trunk Resource Manager

TS Time Slot

TSA Test Signal Analyzer

TSAB Test Signal Analyser type B

TSU Terminal Sub Unit

TTM Trunk Test Module

TU Terminal Unit

TUP Telephonic User Part

U

UA Unnumbered Acknowledge

UAN Universal Access Number

UCP User Controlled Path

UDUB User Defined User Busy

UIC U–interface Circuit

USI User System Interface

UUS User to User Signalling

UWA User Work Area

V

VCIAU Volume Control Information Access Utility

VDU Visual Display Unit

VP Virtual Path

VSSA Very Small Stand Alone

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ANNEX B : DEFINITION BOXES

AAccess Status, 534

ACE = Auxiliary Control Element, 534

ALCN = Analogue Line Circuit, 534

Alignment Pattern, 534

Attendant, 535

BBasic Service, 535

BC = Bearer Capability, 535

BCG = Business Communication Group, 536

CCAE = Customer Application Engineering, 536

Cause, 536

Cave, 536

CDE = Customer Design Engineering, 537

CE = Control Element, 537

Centrex, 537

Cityline, 537

Command, 538

Common (Call Handling), 538

CPC = Calling Party Category, 538

DDDI = Direct Dialling In, 539

DH = Device Handler, 539

DID = Device Interworking Data, 540

DLS = Data Load Segment, 540

DN = Directory Number, 541

DNEH = Directory Number Equivalent of Hundreds, 541

DNET = Directory Number Equivalent of Thousands, 542

DNEU = Directory Number Equivalent of Units, 542

EEDPC = Electronic DataProcessing Centre, 542

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EN = Equipment Number, 543

FFile, 544

Finite Message Machine, 545

GGDN = General Directory Number, 545

Generic, 545

Generic Load Segment, 545

GOS = Generic Overlay Segment, 546

HHDLC = High level DataLink Controller, 546

LLAPD = Link Access Procedure on D–channel, 546

LCE = Logical Control Element Identity, 546

Low penetration data, 547

MMan Machine Language, 547

MMC = Man Machine Communication, 547

MSN = Multiple Subscriber Number, 547

NNATADDR = Nature of Address, 548

OOLCOS = Originating Line Class Of Service, 548

ORJ = Operator Requested Job, 548

PPABX = Private Automatic Branch eXchange, 549

PCE = Physical Control Element Address, 549

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Peripheral Device, 550

PLS = Patch Load Segment, 550

Profile, 550

PTN = Physical Terminal Number, 551

RRBL = Repair Block, 551

Report, 551

RIT = Replacable Item, 551

Route – Subroute, 552

Routeblock –Subrouteblock, 553

RouteCode, 553

SSBL = Security Block, 554

SCSI = Small Computer System Interface, 554

SDN = Search Directory Number, 554

SourceCode, 555

Subscriber Group, 555

TTLCOS = Terminating Line Class Of Service, 555

TN = Terminal Number, 556

Transaction, 556

Trunkgroup, 556

TSU = Terminal SubUnit, 557

TU = Terminal Unit, 557

UUCP = User COntrolled Path, 558

User Buffer, 557

VVirtual Machine, 558

Virtual Path, 558

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The Access Status specifies the type of called devicePossible values are :– Normal Line– Priority Line– Coinbox– Test equipment– ...

Access Status (see LSIF)

ACE is the name given to the modules in the system that have noassociated circuitry. Their only relation with the exchange HW is their con-nection to the network through the Terminal Interface. Therefore, these mod-ules will perform support auxiliary functions for the rest of the system. Giventheir HW independence, the functions to perform are assigned to these Con-trol Elements with more flexibility than to the others, and they may be re-placed by others in case of failure.

ACE = AUXILIARY CONTROL ELEMENT

This is the name of the subscriber line board that serves 16 analog lines.

ALCN = Analogue Line Circuit type N

ALIGNMENT PATTERN

Binary information that travels through channel 0 of the PCM links. This pat-tern is used to recognize each of the 32 PCM channels.This information is inserted on every second PCM link.The PCM link that does not contain the alignment pattern is used to sendalarm information.

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An attendant is a person responsible for traffic assistance.In case of a call towards a PABX without indialling, the call will be routed tothe attendant of the PABX. The attendant can now establish a furtherthrough connection towards the desired extension.

Attendant

The Basic Service is a compressed value of Bearer Capability (BC) andHigh Layer Compatibility (HLC).

The BC is a value between 0 and 15 and the HLC is a value between 0 and32.

Not all combinations of BC + HLC are meaningful

Therefore all meaningful combinations are compressed into the Basic Ser-vice (BS), a value between 0 and 63.

Basic Service 0 corresponds to any BC and any HLC. This is the only validvalue for Analogue subscribers.

Some ISDN classes are Basic Service dependent. This implies that in-formation about these classes has to be provided for each allowed BS.

Basic Service

The BC is a parameter generated by the originating subscriber.The BC specifies what kind of connection the subscriber wants to establish.

The BC is a value between 0 and 15

Most commonly used values are :

– Speech – 3.1 kHz audio – 64kBit/s digital – 128 kBit/s digital – ...

BC = Bearer Capability

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BCG = BUSINESS COMMUNICATION GROUP

The BCG is a service that allows business users belonging to different ex-changes to have a virtual private telecommunication network, supportinganalog and ISDN subscribers as well as PBXs connected to the PublicSwitching Telephone Network.

Software / Data which is applied to customise each physical installation tomeet its specific requirements.It comprises HW related information (LCE–identities, PCE–identities,...)and Call Handling related information (RouteCodes, DNET ranges,...)

CAE = Customer Application Engineering

Cause

A Cause is used to identify each abnormal situation during the setup or re-lease of a call.Examples : – unassigned prefix dialled – No free DTMF receiver could be found, – signalling protocol error – ...The cause value is sent to PATED for Cause analysis.PATED uses the cause value to retrieve a task map. This task map de-scribes the actions to be taken to deal with the abnormal situation.

Remark : Some signalling systems (TUP, ISUP, Q931,...)use also CAUSEvalues to define abnormal situations. It is up to the signalling handling soft-ware in System 12 to translate the System 12 CAUSE into a signalling spe-cific CAUSE or vice versa.

Tunnel with only one CE in an end.

CAVE

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CDE is software which is applicable to one market only. E.g. Signalling, sub-scriber facilities, certain operator requested tasks,...

CDE = Customer Design Engineering

The Control Element is the part of the module in charge of the communica-tion with the other modules; the Control Element, also houses al the soft-ware assigned to the module. Two basic parts may be distinguished in theCE:

–The microprocessor with its main memory, where the main programs that control the module functions are executed.

–The Terminal Interface (TI), which allows for communication between the module and the other modules in the exchange through the switching net-work.

CE = CONTROL ELEMENT

Centrex is an implementation of a private telecommunication network ex-change located on the premises of the public local exchange.

CENTREX

A cityline is an extension of a PABX, having a separate DN and a separateprofile.A call towards the GDN of the PABX or a DDI extension will use the PABXprofile, whereas a call towards the Cityline DN will use the Cityline profile.

Cityline

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A command is a key sent by the operator to the system SW toinitiate a specific action. To do the requested task for each keya certain Command Handler FMM exists as the destination FMM for the giv-en command. The operator has different possibilities to send the command.Beside the different input devices he can specify the command by a certainkey–word or a certain number,the Command Reference Number (CRN).A command may have different (optional and mandatory–) parameters fordetailed task specification with several arguments. All possible combina-tions of command, parameters and arguments with special separators buildup the predefined syntax.

Command

Common software, sometimes called Common Call Handling (CCH) is soft-ware which can be kept common to several markets. E.g. Call Control, CallServices, Resource Management, ...

The evolution of these items is defined in Common Call Handling releases(EC5, EC6, EC7.1, EC7.3, ...)

Common (Call Handling)

The CPC field is used to identify the Type of Call.Possible values are :– Normal Subscriber– Priority Subscriber– National Operator– International Operator– Data Call– Test Call– Mobile subscriber,– ...

CPC = Calling Party Category

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Direct Dialling In or Indialling refers to a PABX where the extensions can bereached immediately from the public network.In the example (see below), extension 69 can be reached by dialling thePABX prefix = 24037, together with the desired extension = 69, so DN =2403769

Remark : The extensions do not have an individual profile. So, for the callto DN= 2403769, the PABX profile (for GDN = 2403700) is used.

DDI = Direct Dialling In

PABX with indialling :

Hunting on prefix 24037

Call routed

to exten-sion

IPABX

(GDN = 2403700)

.

.

.

00

01

99

S12

A single software module that controls, directly, each of the different ex-change circuits.

DH = DEVICE HANDLER

SVTCE_DH

SERVICECIRCUIT

SENDER /RECEIVER

JLTCE_DH

LINECIRCUIT

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The Device Interworking Data (DID) are a set of data in the exchange to en-able the interworking between the originating device and the terminating de-vice (device = Trunk or Subscriber)

There are two types of DID:– Incoming DID– Outgoing DID

E.g: Data concerning echo suppression, suppress backward answer, gain parameters, start sending point, pre–answer timeout, ...

DID = Device Interworking Data

DSN DeviceDevice

DID

S12

DLS is a file on disk and on tape which contains all database data re-lated to a particular CE. Since each CE in the system has a differentset of database data, each specific CE has its own DLS on disk.

DLS = DATA LOAD SEGMENT

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The Directory Number (DN), the number which appears in the telephone di-rectory, is the subscriber’s logical identification.It is the number that is dialled when another subscriber is called.It is constructed according to the CCITT E.164 Specifications.Three cases have to be distinguished:

A. International calls :

DN = Directory Number

Internat.Prefix

CountryCode

NationalDestinationCode

SubscriberNumber

TrunkPrefix

NationalDestinationCode

SubscriberNumber

B. National calls :

C. Zonal calls :

SubscriberNumber

e.g. 00 32 3 240 3769

e.g. 0 3 240 3769

e.g. 240 37 69

DNEH = Directory Number Equivalent of Hundreds

The DNEH value points to a block of 100 consecutive DNs. The last twodigits of the DN are an index in this block.

The DNEH value is calculated with the formula :

DNEH = (DNET – 1)*10 + C + 1,

with C the third last digit of the DN

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The DNET points to a block of 1000 consecutive DNs. The last three digitsof the DN are used as index in this block. For each block of 1000 DNs in anexchange, a DNET is assigned.

Example :

DNET = Directory Number Equivalent of Thousands

DN range DNET

240 0 000 – 240 0 999240 1 000 – 240 1 999

240 9 000 – 240 9 999253 0 000 – 253 0 999253 1 000 – 253 1 999

253 9 000 – 253 9 999

...

...

12

101112

20

...

...

DNEU = Directory Number Equivalent of Units

The DNEU value corresponds to the last three digits of the DN.Suppose the last three digits are C, X and I,,

DNEU = 100*C + 10*X + I

EDPC = ELECTRONIC DATA PROCESSING CENTRE

An EDPC is a processing centre, made up of high capacity processors,which deals with specific data such as charging data in the telephone envi-ronment.

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EN = Equipment Number

The Equipment Number (EN) represents the physical identification of thesubscriber line in the exchange. It consists of the physical or logical Control Element identity of the moduleand the terminal number (TN) within this module (E.G:TN = 1...256 for anASM)

EN = PCE + TN

or

EN = LCE + TN

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A file is a box or space reserved for different entries which belong logicallytogether (e.g. charging data of a group of subscribers). In Alcatel 1000 S12each file has an offline predefined meaning and characteristic (line size, for-mat, structure, ...). From the logical point of view each file is subdivided intorecords like a register of a document is subdivided into chapters and chap-ters into paragraphs to build up small logical units which can be treated sep-erately (create, modify, write). Each file is identified by a logical file numberand the records are specified by their start point, which is called offset (com-parable to a line number in a document).There are different possibilities to organise a logical file physically, depend-ing on the physical medium. We can put everything which logically belongstogether into the same area, like a register or chapter of a document intoone binder, or we can distribute parts of one file to different physical areas toorganise them in another way (e.g. refering to the record size). The smallestphysical unit where we can store different records is one block of 2 Kbytesize, like a fixed number of lines per page or characters per line; thereforethe maximum size of one record is 2 Kbyte (miniumum size: 1 byte).

File

FileDir

A-E F-P O-T U-Z

File

1

File

2

File

3

File

4

1. File1.1 Record

1.2 block

"filing"

006BC011.DRW

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An FMM is the basic software building functional block and has the follow-ing properties:

–It can communicate with other FMMs, but only through messages.

–From the outside, an FMM is a “block box”, i.e., its internal structure is not known to the rest of the system. Its functional behaviour is unambiguously determined by the set of mesages it sends and receives.

–It may be in one of several different states and the transactions betweenthem are allowed. There is a limited set of messages defined for each state.After receiving a message, the FMM may generate and transmit output mes-sages and its state may change.

FMM = FINITE MESSAGE MACHINE

The GDN of a PABX is used as a unique identity of the PABX in System 12.The profile of the PABX is stored on behalf of this GDN.Calls towards this GDN result in hunting all accesses towards the PABX.

GDN = General Directory Number

Software which is fundamental to the system and is kept generally applica-ble to all markets. E.g. Operating System, Database, Input/Output mecha-nisms,...

The evolution of such items is defined in System Kernel Releases (R5.2, R6,R7.1, R7.2,...)

Generic

File on disk or tape which contains the resident programs code and datasegment for a particular CE in the system. One GLS is used to load everyCE of the same type.

GLS = GENERIC LOAD SEGMENT

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File on disk or tape which contains the code and data segment, and thepatches, for an overlay program.

GOS = GENERIC OVERLAY SEGMENT

A general and universally accepted way of formatting the link level frames.The LAPB of X25 and the LAPD of ISDN belong to this family.

HDLC = High level DataLink Controller

This is the HDLC link level frame format, used in the subscriber link in theISDN environment to protect the sending of the signalling messages by theD channel.

LAPD = Link Access Procedure on D–channel

Besides a PCE (Physical Control Element Address) every module receivesalso a Logical Control Element (LCE) identity. When FMMs send messagesto other CEs, then usually the LCE–id is used. Inside the Operating Systemthis LCE–id is translated into the PCE–address so it is possible to calculatethe selects and send the message.How is the LCE used? Originating ASM modules contact destination ASMs by means of the LCE–id. Remember also that ASMs have a X–over partner. E.g: An ASM sends a message to ASM1 (LCE–A). If the latter is out of ser-vice, the operating system knows about this and will route the message tothe X–over partner ( LCE–A is linked to PCE–B), which is ASM2.

LCE = Logical Control Element Identity

ASM (Normal Routing)

LCE–A PCE–A (=ASM1)

LCE–B PCE–B (=ASM2)

ASM (X–over Routing)

LCE–A PCE–A (=ASM1)

LCE–B PCE–B (=ASM2)

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Low penetration data

The Low penetration data is the part of the subscriber data, describing thefacilities of the subscriber. It consists of both originating and terminatingdata.The Low penetration data is always stored at LSIF level.Examples : – Basic service dependent data (only for ISDN subscribers) – Abbreviated dialling information – Call forwarding data – ...

By means of particular communication channels between several devices and ter-minals and the P&L modules, the operator can manage all the exchange functions.To do this, a multitude of commands are provided. Each of these commands startsa software module that performs the required function.

MMC = MAN MACHINE COMMUNICATION

The Man Machine language is used by an operator (man) to give commandsto and receive results from the System 12 exchange (machine).The Man Machine language is conform to the CCITT recommendation forman–machine language for telephonic exchanges (see CCITT Yellow Book,Volume VI Part II, Recommendations Z311–Z317, and the contributions ofStudy Group XI).

Man Machine Language

MSN = Multiple Subscriber Number

A subscriber can subscribe to more than one Directory Number (DN).Thedifferent DNs are called MSN1 ... MSNx (x=8 maximum). Every MSN canhave its own data profile with its own facilities.E.g: MSN1 is the normal subscriber number.

MSN2 is given to business people who are transferred to theoffice in case of no answer.

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The Nature of Address specifies the layout of the received digit stream.Possible values are :– INTAL (international)– NATIONAL– ABD (Abbreviated Dialling)– Unknown– ...

NATADDR = Nature of Address

The OLCOS data is that part of the subscriber profile that is needed to setup an originating call from that subscriber.Most important fields are : – Dial Type (Rotary, PB receiver, Combined set) – DNET and DNEU value of subscriber – Subscriber Group identity – Number of digits to be dialled before prefix analysis starts, – ...

OLCOS = Originating Line Class Of Service

An operator Requested Job is created by the IOS for each syntactically cor-rect input of a command and identified by a Job Sequence Number (4 digitsas a job counter) and date of the input, the address of the input device andthe operator and exchange identification. A job exists till the final result issent to all specified output devices.

ORJ = Operator Requested Job

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A PABX is a switching network, located on the customer’s premises, servinga number of extensions forming a single subscriber group. It is connected tothe exchange by means of a number of single lines (Analogue or BA) and/ora number of trunks (Analogue, CAS digital or PRA).The PABX is identified by means of a General Directory Number (GDN).The extensions of the PABX are invisible to the public exchange.In the case of an indialling PABX (DDI), the extensions can be reached fromthe public network, but no individual profile is allocated to those extensions.For a call to/from an extension, the profile assigned to the GDN of the PABXis used.

PABX = Private Automatic Branch eXchange

PABX

(GDN = 2403700)

.

.

.

00

01

99

Collection ofsingle linesand/or trunks

S12

This is the physical address of the module . Every module connected to thedigital switching network has a unique Network Address, which is also calledthe DCBA–Address. The only way to change this address for a specific mod-ule is by changing its physical position in the racks so that it is conected to adifferent access switch and/or access switch port.

PCE = Physical Control Element Address

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Peripheral Device

In addition to telephonic devices (e.g. subscriber set) the peripheral devices(PC, printer, disk, magnetic tape, ...) are the operational tools connected toAlcatel 1000 S12 exchanges. Each device is physically defined by its HWconfiguration, that means what kind of HW is connected in which way towhich HW of the exchange. This can be described by a mnemonic, whichconsists of an abbreviation for the type of the device, one character to speci-fy the CE, which is responsible for controlling the device and a number tocount the devices controlled by the same CE (e.g. a PC controlled by PLCEwith NA H’C may have the mnemonic VDUA1; VDU stands for visual displayunit – independent of the manufactures). Logically each peripheral device isdefined by one or several numbers, the Logical Device Identities (LDE-VID). The physical configuration which stands behind the LDEVID is datadriven. Standard values are defined in the O&M Manuals (SI 69) with somegeneral rules to translate logical devices into physical and vice versa.

PLS is a file on disk and on tape, which contains the patches to the pro-grams for a particular GLS. These patches are created to improve or to cor-rect the programs designed for a CE.

PLS = Patch Load Segment

A profile is the collection of all data of one subscriber.It consists of – Originating Line Clas Of Service (OLCOS) – Terminating Line Class Of Service (TLCOS) – ISDN related data – Low penetration data

Profile

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PTN = Physical Terminal Number

This is a word received from the hardware which uniquely identifies a sub-scriber. The layout is as follows:

PTN = L1L00d dddd 0000 tttt

* L1 = 1 if the subscriber PBA is connected to port pair 3 of the terminal interface.* L0 = 1 if the subscriber PBA is connected to port pair 1 of the terminal interface.* ddddd : indicates the PBA number of the subscriber

(for ALCN = 00000 upto 00111)* tttt : indicates the subscriber number for the indicated PBA.

(for ALCN = 0000 up to 1111)

REMARK: The PTN is translated into the TN (see Terminal Number).

An RBL is the minimum group of SBLs which must be taken out of service toallow an RIT to be replaced. The SBLs must be taken out of service beforethe RIT can be removed.

RBL = Repair Block

A report is the answer from the system SW to a certain command sent bythe operator to display the result of an ORJ or a message of the system SWto the operator. Each report–layout (independent of the contents) initiated bydifferent commands or the system SW itself, is defined by a Report Refer-ence Number (RRN) and described in the O&M Manual (System reports).

Report

A Replaceable Item is the smallest item which can be replaced.

E.g.: A printed board, a VDU, a DC/DC converter,....

From the exchange point of view, the RIT is the basic unit of hardware andcan be a part of a SBL or consist of several SBLs, depending on its type.

RIT = Replaceable Item

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A Route is the collection of all trunks between two adjacent exchanges.

Route – Subroute

Route TrunkgroupsSubroutes

A route can be subdivided into subroutes, depending on the requested BCand the required signalling system.Example : We can reserve some trunk groups for speech calls only and somefor 64Kbit/s digital calls. In this case we define two subroutes. The selectionof subroute within the route is in this case based upon the BC.

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A Routeblock is the collection of all Routes to reach a certain destination.This destination does not have to be an adjacent exchange.

Routeblock – Subrouteblock

Exch A

Exch B

Exch C

Exch D

Exch ERouteblock Routes

To Exch BTo Exch CTo Exch DTo Exch E

Route AB Route AC+Route ABRoute AC

Route AB Route AC+Route AC

+

Route AB

Route AC

A Routeblock can be subdivided into Subrouteblock depending on the re-quired signalling system and the requested BC. Each subrouteblock con-sists of a number of subroutes. The selection of a subrouteblock within arouteblock is based upon the BC and required the signalling system.

RouteCode

A RouteCode is used to identify a RouteBlock. In the case of an outgoingcall, PATED translates the dialled prefix into the Routecode, used for Trunk-Search.The Trunk Search programs (TRC/TRA) use this RouteCode, together withthe requested signalling system and BC, to select an appropriate subroute-block.This procedure is called RouteCode Modulation .

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An SBL is a group of hardware circuits which perform a set of functions. TheSBLs are arranged in such a way that if one of the functions is malfunction-ing, the remaining functions can no longer be used by the exchange. Theentire set (read: SBL) can therefore be removed from service.In case of problems, there are test programs (Diagnostic Tests) which areable to couple the error to an SBL, in other words to locate the faulty SBL.In case of failure, the corresponding SBL(s) is (are) taken out of service. Inthis way an SBL can have a number of different states, each indicatingwhether the SBL is contributing to the functioning of the exchange.SBLs do not overlap but are organized on a hierarchical basis so that failureof an SBL causes any lower level SBLs to become ineffective. These depen-dent SBLs are automatically taken out of service along with the primary sus-pect SBL. An exchange is the grouping of all the SBLs defined within it.

SBL = Security Block

The SCSI is a parallel, multimaster I/O bus that provides a standard inter-face between computer and peripheral devices. It implements complete log-ical commands and true peer– to–peer communication.The former simplymeans that all SCSI devices use the same communication protocol. All pe-ripheral devices, in the P&L modules, are connected a to the CE by the cor-responding PBA which drive the SCSI bus and drive the devices.

SCSI = SMALL COMPUTER SYSTEM INTERFACE

The Search Directory Number of a PABX or huntgroup is used to identify theaccesses towards this PABX/huntgroup. A call towards this SDN results inthe hunting of all connections defined by this SDN.

SDN = Search Directory Number

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SourceCode

The SourceCode identifies the type of calling equipment.The sourcecode consists of 3 parameters :A. Type of equipment (Subscriber, trunk, test equipment, operator,...)B. SourceCode Number :further classification of the type of equipment. For trunks, this is the Trunkgroup number For subscribers, this is the Subscribergroup number,...C. An indication whether a Packet switched or Circuit switched call is in-volved.

All subscribers having the same treatment in the exchange are grouped inone subscriber group.Example : If subscribers, connected to an RSU receive a different treatment,all RSU subscribers are grouped in one subscriber group. All non–RSUsubscribers are then grouped in another subscriber group.

Subscriber Group

The TLCOS is that part of the subscriber data that is needed to set up callstowards that subscriber.Most important fields are : – Type of connected device (Coinbox, normal line, operator,...) – Call forwarding information, – reverse charging indication, – ...

TLCOS = Terminating Line Class Of Service

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TN = Terminal Number

This number uniquely identifies the subscriber within the X–over paired mod-ules. Because there are up to 128 subscribers connected to one module, thenumber is in a range of 1 to 256.

1 ... 128 = Even module.129 ... 256 = Odd module

The software receives the PTN (see PTN) from the hardware and translatesit into the TN and vice versa. In the software the TN is used for database ac-cess.

REMARK: For ISDN subscribers there are only 8 subscribers/PBAcompared to the 16 subscribers/PBA for analogue. Both modules (ASM orISM) use the same BPA which means 16 TNs / slot for analogue and 8 TNs /slot for ISDN. This is done by skipping 8 TNs for the ISDN. So the ISDN TNsare in the ranges: 1...8, 17...24, ... , 241...248, which is a total of 128 sub-scribers.

In the Protocol plane (SIG), we talk about a Transaction, whenever a call isestablished to/from a subscriber or a trunk.The SIG allocates a Transaction Control Block to keep information abouteach transaction. This information comprises : Cluster path identity, Net-work path Identity, TN of subscriber/trunk, ...

Remark: A subscriber can have more than 1 transaction at the same time.E.g: ISDN subscribers have 2 B channels, so they can set up 2 calls at atime. Analogue subscribers can place an existing call (transaction) in holdand start a second call (transaction)

Transaction

A trunk Group is the collection of all trunks towards an adjacent exchange,having the same properties : Same signalling system(R2, TUP, ISUP, ...), Same Transmission characteristics (analogue, digital, ...) ...

Trunkgroup

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Group of modules connected to the network, using two Access Switches.

TSU = TERMINAL SUB–UNIT

MODULE 0

MODULE 1

MODULE 7

ACCESSSWITCH

ACCESSSWITCH

8

9

10

11

12

13

14

15

8

9

10

11

12

13

14

15

TO GROUPSWITCHES

TO GROUPSWITCHES

0

1

7

0

1

7

Set of 4 TSUs joined to the same multiport that belongs to the first stage.

TU = TERMINAL UNIT

The user buffer is a memory area to support the sending of messages withmore than 40 bytes of data. There are different sizes of user buffers: 64,128,256, 512, 1024, 2048, and 4096 bytes long. These memory areas arelocated in a particular memory zone, and are managed by the operating sys-tem. When a process needs a user buffer, it requests the buffer to the oper-ating system, which locates a free one in the pool zone and associates it tothe requesting process. Once the user buffer has been used to send thedata, the process returns it to the pool by requesting to the operating sys-tem.

USER BUFFER

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User controlled path are two–way paths that are established and releasedby the user (process) request.These paths are associated to two processes,one of them in each CE connected to the path, and every message that en-ters to the CE via the UCP is directly delivered to the associated process bythe operating system.

UCP = USER CONTROLLED PATH

Set composed by a real machine (example: line circuit), plus the programs that pro-vide abstract operations to the users of this machine (in the example, JLTCE–DH).

VIRTUAL MACHINE

LINE

CIRCUITJLTCE_DH

OTHERUSERS OF

LINE CIRCUIT

VIRTUAL MACHINE

Virtual Paths are one–way temporary paths established through the DigitalSwitching Network, to send a message buffer from one CE to another.Theusual procedure is to establish the path, by means of SELECT commands,to send the message buffer (using the ESCAPE protocol), and finally, to re-lease it by means of more than two CLEAR commands.

VIRTUAL PATH

Alcatel 1000 S12 Functional Description

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Transcript of Alcatel 1000 S12 Functional Description