Common Channel Signalling_ss7

1 © NOKIA 2003 CCS7 Theory/ 6-65811/ 02.2003/ v 4.0

Common Channel Signalling Common Channel Signalling in NSSin NSS


ObjectivesOn completion of this module, you should be able to:• List two examples of circuit-related signalling and four examples of non circuit-

related signalling• List necessary CCS7 protocols needed in the MSC, HLR, BSC, MGW, and the

PSTN exchange • State the reason why some protocols have the name “User Parts" and some of

them have the name "Application Parts"• Give an example case in which SCCP routing is needed and MTP routing cannot

be used to route the signalling message to the destination • List at least one function of MTP-level 3, SCCP, MAP, BSSAP, RANAP, ISUP,

and INAP • List the main purpose of IMSI analysis • Give two different IMSI analysis types and explain why and when these two

types are used • Write a list of necessary definitions that have to be done in our MSC when a

new MSC is added to the existing GSM/UMTS network and the new MSC has a direct signalling connection to the MSC

• Write a list of necessary CCS7 definitions that have to be created in core networks when an SMSC is integrated to the network

• Describe the protocol stack used in case of IP trunking (optional) • Explain the procedures of a call setup over IP trunking (optional)


What is signalling?

Signalling is any transfer of data that enables speech and data connection between users and supports mobility management and GSM services handling.

Uses of signalling• speech and data connection (to set up, supervise, and

release a call)

• mobility management (location update, handover)

• subscriber administration (including all basic and supplementary GSM services)


Signalling message structure

Origin Destination Circuit information

Origin Destination Other information

•Location data (LAI)•TMSI/IMSI•Short message•C-number (FORW)•Target cell (Handover)

CIC (Circuit Identification Code)1. Circuit-related

2. Non-circuit-related

Other information


Example of circuit-related and

non-circuit-related signalling

0 D 2 0

X X

2

0

D

X X

D

2

X 0

2 0

X 0 0

2

0

0

2 X

0

00

D

D

0

0

2

0

2

D

X D

D 2 0

GMSC/VLR

HLR

X 0

D 0

VMSC/VLR

A-sub

B-sub

1. SRI (B-MSISDN)

4. SRI Response (MSRN)

3. PRN Response (MSRN)

2. PRN (B-IMSI)5. Call setup (

CIRCUIT

CICMSRN + )

6. Paging

Non-circuit-related signalling

Circuit-related signalling


Physical layer

Data link layer

Network layer

Transport layer

Session layer

Presentation layer

Application layer

MTP (levels 1-3)

User Part

(Common part)(PSTN, ISDN,

GSM)

User Part

OSI Reference Model Common Channel Signalling No. 7

Application Part

(GSM specific part)

SCCP

Layer

1

2

3

4

5

6

7

Level

1

2

3

4

The OSI reference model vs. CCS7 protocols


CCS7 protocols in various network elements

MAP / INAP

TCAP

SCCP

MTP

BSSAP MAP/INAPTCAP

SCCP

MTP

TUP NUPISUP

SCCP

MTP

BSSAP

SCCP

MTP

MSC/VLR

HLR/EIR/AC

PSTN Exchange

BSC

TUP NUPISUP


Multimedia Gateway

The main function of the Multimedia Gateway (MGW) is to enable interworking between the MSC and the UMTS Radio Access Network (UTRAN).


MTP

TUPNUPISUP

User parts


CIC OPC DPC

Heading codeH1 H0 Label

Signals andindicators

TUPmessage

Labelstructure CIC: Circuit Identification Code

12bits 14 or 24 bits 14 or 24 bits

The TUP message structure

Only circuit related signalling messages


X0 D0 D20

VMSC/VLR

PSTNexchange-A

PSTNexchange-B

Example of a TUP connection


X0 D0 D20

VMSC/VLR

PSTNexchange-A

PSTNexchange-B

Setup (Dialled number)

Process Informationand make connection

Setup (Ringing)

Connect

Conversation

IAI (CIC+dialled digits)

IAI (CIC+dialled digits)

ACM (CIC)ACM (CIC)

Alert

ANU (CIC)ANU (CIC)

Connect

Example of a TUP connection


CIC OPC DPC

LabelUser dataISUPmessage

Labelstructure SLS

12bits 4bits 14 or 24 14 or 24 bits

8n bits

The ISUP message structure

Only circuit-related signalling messages


SLS table

NEO:NA0,30:;DX 200 MSC 2000-12-12 06:34:00SIGNALLING POINT LOAD SHARING SP EXT OUTNET SP CODE H/D NAME SLS NET SP CODE H/D LINK PCM-TSL SLS=== ================== ===== ==== === ================== ===== ======= ===

NA0 0030/00048 BSC1 0 NA0 0030/00048 2 72-16 0 1 NA0 0030/00048 9 75-16 1 2 NA0 0030/00048 3 73-16 2 3 NA0 0030/00048 8 74-16 3 4 NA0 0030/00048 9 75-16 4 5 NA0 0030/00048 2 72-16 5 6 NA0 0030/00048 8 74-16 6 7 NA0 0030/00048 3 73-16 7 8 NA0 0030/00048 2 72-16 8 9 NA0 0030/00048 8 74-16 9 10 NA0 0030/00048 2 72-16 10 11 NA0 0030/00048 3 73-16 11 12 NA0 0030/00048 8 74-16 12 13 NA0 0030/00048 9 75-16 13 14 NA0 0030/00048 9 75-16 14 15 NA0 0030/00048 3 73-16 15


Signalling link set definition

NSI:NA0,30;DX 200 MSC 2000-12-12 06:34:20INTERROGATING SIGNALLING LINK SET DATANET SP CODE H/D LINK SET LS STATE LINK SLC --- ------------------ ---------- -------- --------NA0 0030/00048 17 BSC1 AV 2 0 3 1 8 2 9 3


X0 D0 D20

VMSC/VLR

PSTNexchange-A

PSTNexchange-B

Example of an ISUP connection


X0 D0 D20

VMSC/VLR

PSTNexchange-A

PSTNexchange-B

Setup (Dialled number)

Process Informationand make connection

Setup (Ringing)

Connect

Conversation

IAM (CIC+dialled digits)


ACM (CIC)ACM (CIC)Alert

ANM (CIC)ANM (CIC)Connect

Example of an ISUP connection


MTP

SCCP

BSSAPMAP / INAP

TCAP

Application parts


What are application parts?

• All application parts that use services provided by SCCP level can be called as SCCP subsystems or SCCP users.

• For example, SCCP subsystems are• BSSAP• MAP• INAP


Base station subsystem application part

BS

SA

P

BSSMAP

DTAP

BSC

L

MSC/VLR

MS

DTAP (Call setup, location update)

BSSMAP

(Paging)

Both circuit-related and non-circuit related signalling messages


MAP

VLR

MSC

VLR

MSC

HLR

EIR

E G

F

B

B

D

C

Only non-circuit-related signalling messages


MTP

SCCP

TCAP

MAP-M MAP-V

MTP

SCCP

TCAP

MAP-H MAP-E

MSC/VLR HLR/AC/EIR

SCCP subsystems of MAP

OSI(level)

1- 2

3

7

4-6


INAP

NOKIA TELECOMMUNICATIONS

SSP SCP

InitialDP : used to start dialogue between SSP and SCP

ReleaseCall : SCP instructs SSP to release a call

Only non-circuit-related signalling messages


Iu interface control plane

Core NetworkDom ains

RNC

Physical Layer Physical Layer

ATM ATM

AAL5

RANAP RANAP

Convergence Protocol(s) Convergence Protocol(s)

AAL5

Iu


RAB and CN domains

IuCN Circuit Domain: - RT Traffic - Constant Bit Rates

CN Packet Domain: - NRT Traffic (RT Traffic) - Variable Bit Rates

RAB


Bearer between the UE and core network circuit domain

Bearers to Setup or Modify:

Bearers to Keep:

Bearers to Release:

- Bearer ID - AAL2 ID - Binding ID (transport)

- Bearer ID

- Bearer ID - Release Cause

BS RNC RNC CN - Circuit Domain

Iub Iur Iu

RANAP

RANAPNBAP

= Radio Access Network Application Part= Node B (BS) Application Part

NBAPRANAP


RANAP Bearer Assignment

RNCBSUu Iub Iu

RAB Assignment Request

RAB Assignment Complete

Core NetworkDomains

RAB is configured to be used over the existing Radio Link(s)


RANAP Bearer Deletion

RNCBSUu Iub Iu

RAB Assignment Request

RAB Release Request

RAB Assignment Complete

Core NetworkDomains

RAB - Radio Link relationship removed


RANAP Serving RNC Relocation

IuIur Iu

Relocation Required

Relocation Command

SRNC Relocation Commit

Relocation Detect

Relocation Complete

Relocation Request

Reloc. Req. Ack.

Relocation Detect

Relocation Complete

Core NetworkDomain(s)

SourceServing

RNC

TargetServing

RNC

RAB(s) Assigned

RAB(s) Released

Iu Release

To the target RNC withRNSAP:


Signalling Protocol Stack in MGW


Summary

Part CCS7 user

Type of signalling

Required services from

Example Used between

TUP

NUP

User Parts

ISUP


MTP Message Transfer Part

Setup (IAM) Supervise(ACM, ANM) Release (REL) a call

PSTN-MSC MSC-MSC

Paging, control handover and tracing procedure

MSC-BSC (BSSMAP)

BSSAP Both circuit-related and non-circuit-related

Set up a call, authentication checking, activate/ deactivate supplementary services and send/receive short message services

MSC-MS (DTAP)

MAP Non-circuit-related

HLR inquiry (only MTC) IMEI checking Update location Inter-MSC handover Inter-VLR inquiry

MSC-HLR MSC-EIR VLR-HLR MSC-MSC VLR-VLR

INAP Non-circuit-related

SCCP Signalling Connection Control Part

Initial Detection Point Release call

SSP-SCP SCP-SSP

RANAP Paging, Set up a call, Set up the bearers, RANAP Serving RNC Relocation Authentication checking, activate/ deactivate supplementary services, and send/receive short message services Handover control, power control, bearers allocation, codes allocation

RNC-Core Network Domain

Core Network Domain-UE

RNC-UE

Application Parts

RNSAP

Both circuit-related and non-circuit-related

MTP and SCCP

Serving RNC Relocation in Iur interface by Relocation Commit

RNC-RNC


Summary, cont

Part CCS7 user

Type of signalling



TUP

NUP

User Parts

ISUP




PSTN-MSC MSC-MSC


MSC-BSC (BSSMAP)



MSC-MS (DTAP)







SSP-SCP SCP-SSP




RNC-UE

Application Parts

RNSAP


MTP and SCCP


RNC-RNC

Part CCS7 user

Type of signalling



TUP

NUP

User Parts

ISUP




PSTN-MSC MSC-MSC


MSC-BSC (BSSMAP)



MSC-MS (DTAP)







SSP-SCP SCP-SSP




RNC-UE

Application Parts

RNSAP


MTP and SCCP


RNC-RNC


User Parts

SCCP Subsystems

MTP

SCCP

TCAP

MAP-M MAP-V MAP-H MAP-E INAP

BSSAP

MTP

TUPNUPISUP


Signalling routing methods

MTP

SCCP

Signalling messages from upper level

2.by SCCP

1.by MTP

to other network elements


1. Routing by MTP

Level 1 Physical Connections

MessageTransfer

Part (MTP)

Signalling Message Handling

Level 2 Data Link Control

Level 3 Message

Signal unit

Bit

Data unit


F CK SIF SIO LIFIB

FSNBIB

BSN F

LIFIB

FSNBIB

BSN F

LIFIB

FSNBIB

BSN F

F CK

F CK

SF

First bittransmitted


First bit transmitted

8 16 8n, n>2 8 2 6 1 7 1 7 8

8 16 8 or 16 2 6 1 7 1 7 8

8 16 2 6 1 7 1 7 8

CK Check Bits SF Status FieldF Flag SIF Signalling Information FieldLI Length Indicator SIO Service Information OctetFSN Forward Sequence Number BIB Backward Indicator BitsBSN Backward Sequence Number FIB Forward Indicator Bits

(a) Basic format of a message signal unit (MSU) , Length Indicator (LI) >2 =<63

(b) Format of a link status signal unit (LSSU) , Length Indicator (LI) =1or 2

(c) Format of a fill-in signal unit (FISU) Length Indicator (LI) =0

Signal Unit types of MTP level 2

1. MSU

2. LSSU

3. FISU


Are thereany errors?

MSU

No

Message handling Network Management

Are thereany errors?

LSSU

YesYesError

handling

No

Level 2

Level 3

TUP ISUP SCCP

Network management messages

To othernetworkelement

Functions of MTP level 2 and level 3


Discrimination

DPC = own SPC

Routing

Distribution

DPC own SPC¹

Network ManagementSCCPTUPISUP

MTP users

From MTP level 2To MTP level 2

Signalling MessageHandling

Message handling in MTP level 3


F CK SIF SIO LIFIB

FSNBIB

BSN FFirst bittransmitted 8 16 8n, n>2 8 2 6 1 7 1 7

8

User Data

SIO

SIO

SIODPCOPCSLC

User Data DPCOPCSLS

User Data DPCOPCSLS

CIC

SIOUser Data DPCOPCCIC TUP

ISUP

Network Management

SCCP

Structure of messages from MTP users


SLS OPC DPC

OPC Originating Point CodeDPC Destination Point CodeSLS Signalling Link Selection

User informationsubfield

Label

DCBASubservice

field

DCBAService

indicator(SI)

Signalling Information Field (SIF)

Service informationoctet (SIO)


4 bits 14 bits 14 bits 4bits 4 bits

Routing label 0000-0011 : IN00100-0111 : IN11000-1011 : NA01100-1111 : NA1

0000 : SNM0001 : SNT0011 : SCCP0100 : TUP0101 : ISUP

Structure of SIF, SIO, and routing label


Discrimination

DPC = own SPC

Routing

Distribution

ISUP in MSCIAM (DPC,CIC)ISUP

MTP

ISUP in PSTNIAM (DPC,CIC)

X0 D0 D20

MSC/VLR

PSTNexchange-A


DPC SIO = ISUP

MTP routing example


Summary of routing by MTP

• To be able to route out signalling message by MTP• Upper layer has to know DPC (Destination Point Code)

• What will happen if DPC is unknown from upper layer?


Yes, you are right.We need routing by SCCP.


BasicConnectionless

Service

SequencedConnectionless

Service

BasicConnection-

orientedService

Flow ControlConnection-

orientedService

ConnectionlessServices

Connection-orientedServices

0 1 2 3

Services provided by the SCCP

Protocol Class

2. Routing by SCCP

Who are users of SCCP?

Why these three application parts need SCCP service?


BSSAPMAP INAP Application Level

SCCP LevelConnection orientedServices

ConnectionlessServices

Use of SCCP services


Two types of routing by SCCP

1. Routing on label (DPC, OPC, or SLS)

2. Routing on GT (Global Title)


Global Title

• Global Title (GT) is an address used to identify the destination of the signalling message. For examples, HLR-ISDN, MSC-ISDN, or SMSC.

GT Format: Numbering PlanDigits

E.164358 60 2210

E.16486 138 00100500

HLR address

SMSC address


BSSAP MAP INAP

Is DPC contained in the message?

Yes No (there is a GT)

Routing on label(do nothing)

Routing on GT(GT analysis)

Message handling

Application parts

SCCP

MTP

Routing on label and on GT


Signalling routing (MTP and SCCP)

BSSAP MAP INAP

RI = GT

Application parts

SCCP

MTP

SIO = SCCP

GT Analysis

Other DPC

Discrimination

DPC = own SPC

Routing

Distribution

DPC is not own SPC

RIRI = SSN

DPCOwn SPC

SSN


GT Analysis

• GT analysis is used to analyse a GT to find out the destination of the signalling message.

GTAnalysi

s

Numbering Plan

Digits

DPC

RI

When the DPC receives the message• RI = SSN, there is no need for GT analysis.• RI = GT, the GT analysis has to be performed.


International Roaming, the first location update

• MS sends IMSI to the VLR in VPLMN• VLR will send "update location" message to HLR• Does the VLR know SPC of the HLR?• Does the VLR know HLR address?• How can the VLR send LU message to the HLR?

Example of SCCP routing on GT


IMSI analysis

IMSI analysis is used to analyse IMSI to determine where the subscriber's HLR is.

IMSIAnalysi

s

IMSI or E.212

Hybrid no. or E.214

MCCMNCMSIN Operator No.MSIN


Examples of hybrid number (E.214)

35850MSIN

86139 MSIN

86130 MSIN

Finnish

China A

China B

Operator name

Hybrid number

D O C U M E N T T Y P E 1 ( 1 )

T y p e U n i t O r D e p a r t m e n t H e r eT y p e Y o u r N a m e H e r e T y p e D a t e H e r e

D O C U M E N T T Y P E 1 ( 1






D O C U M E N T T Y P E 1 ( 1 )


O perator C C +N DC O peratornum ber

M SIN(part of .2 1 2 )

H ybrid num ber(E .2 1 4 ):O perator num ber+M SIN

Finnish 3 5 8 5 0 3 5 8 5 0 1 2 3 4 5 6 7 8 9 0 3 5 8 5 0 +1 2 3 4 5 6 7 8 9 0

C hina A 8 6 1 3 9 8 6 1 3 9 0 0 0 0 0 0 0 0 0 2 8 6 1 3 9 +0 0 0 0 0 0 0 0 0 2

C hina B 8 6 1 3 0 8 6 1 3 0 0 0 0 0 0 0 1 2 3 4 8 6 1 3 0 +0 0 0 0 0 0 1 2 3 4


International roaming,the first location update

IMSIAnalys

is

IMSI or E.212

Hybrid no. or E.214

GTAnalys

is

Message handling

SCCP routing on GT

MTP


Home subscriber, the first location update

• MS sends IMSI to the VLR in HPLMN• VLR will send "update location" message to HLR• Does the VLR know SPC of the HLR?• How can the VLR send LU message to the HLR?

Example of SCCP routing on label


IMSI analysis

IMSI analysis is used to analyse IMSI to determine where the subscriber's HLR is.

IMSIAnalysi

s

IMSI or E.212

DPC of the HLR

MCCMNCMSIN


Home subscriber,the first location update

IMSIAnalysis

IMSI or E.212

DPC of the HLR

Message handling

SCCP routing on label

MTP


SCCP

MTP

PSTN

Exchange

TUP

NUP

ISUP

SCCP routing by PSTN

PSTN exchange supports SCCP routing both on label and on GT.


Example of IMSI and GT analysis

MSC1 GMSC4

MSC7

MSC5 MSC6

HLR1

HLR2

MSC2 GMSC3 GEXC1

EXC3

EXC2

EXC4

EXC5

NA0NA0

NA0

IN0 IN0

PSTN FINLANDTHAILAND

GEXC6

HLR-ISDN:358602210001

MSISDN:6618810001

SCCP

MTP

MSC1 GMSC3 GMSC4 HLR1

2. LU_Request (Called-E.214, Calling-MSC1-ISDN)

3. LU_Response (Called-MSC1-ISDN, Calling-HLR1-ISDN)

4. LU_Acknowledge (Called-HLR1-ISDN, Calling-MSC1-ISDN)

1. IMSI analysis

2. 2.

3.

3.3.

4.4.

4.

NP = E.214

DIG = 358

DPC=GMSC3 NET=NA0

RI=GT

NP = E.214

DIG = 358

DPC=GEXC1 NET=IN0

RI=GT

NP = E.214

DIG = 3586022

DPC=HLR1NET=NA0

RI=GT

NP = E.214

DIG = 3586022

DPC=OWN

RI=GT or SSN

NP = E.164

DIG = 66

DPC=GMSC4 NET=NA0

RI=GT

NP = E.164

DIG = 66

DPC=GEXC6 NET=IN0

RI=GT

IMSI: 24406022XXXXXXXXX

NP = E.164

DIG = 358

DPC=GMSC3 NET=NA0

RI=GT

NP = E.164

DIG = 358

DPC=GEXC1 NET=IN0

RI=GT

NP = E.164

DIG=6618810001

DPC=MSC1 NET=NA0

RI=GT

NP = E.164

DIG=6618810001

DPC=OWN

RI=GT or SSN

NP = E.164

DIG=35860221001

DPC=HLR1 NET=NA0

RI=GT

NP = E.164

DIG=35860221001

DPC=OWN

RI=GT or SSN

IMISI = 24406 E.214 = 35860


BSC

SPC=35

MSC

SPC=25

GMSC

(NA0)SPC=30(IN0) SPC=10

PSTN

(NA0)SPC=30(IN0) SPC=20

PSTN

SPC=10

PSTN

SPC=20

PSTN

(NA0)SPC=40(NA1)SPC=10

BSC

SPC=45

MSC

SPC=35

HLR

SPC=40

GMSC

(NA0)SPC=50(NA1)SPC=20

NA0 NA0

NA0

IN0

NA1

IMSI analysisin MSC

GT analysis in GMSC

GT analysis in PSTN

GT analysis in PSTN

GT analysisin GMSC

GT analysisin MSC

GT analysis in HLR

IMSI and GT analysis


MTP

TUP ISUPSCCP

BSSAPMAP

Create MTP definitions (SL, SLS, SRS)

Define SCCP to new MSC

Create SCCP subsystem(MAP-M, MAP-V)

Start procedure

1

2

3

Creation of MAP

Creation of ISUP

Create ISUP-ET1

TCAP

Adding a new MSC to the network


TCAP

MAP-H

SCCPMTP

MAP-E MAP-VTCAP

SCCPMTP

MAP-MISUP/TUP

BSSAP

SCCP

BSSAP

SCCPMTP

ISUP/TUP

MTPMTP

ISUP/TUP

HLR MSC BSC

MSC PSTNMAP-M

TCAPSCCP

MAP-V

Protocols used within PLMN


CCSUBSU

ET

ET

ETHLR

PSTN

BSC

ECUGSW

CCMU

Hardware used in CCS7


MTP

SCCP

TCAP

ISUP/TUP

MAP

OSI

layer 1

layer 2

layer 3

layer 4

layer 5

layer 6

layer 7

TCAP within CCS7


Application 1 Application 2

INVOKE -component

OPERATION

Dialogue 1

Dialogue 2

Dialogue 3

Result

TCAP dialogue


ET:__ ET:__

ET:__ET:__

MSC1

MSC2

MSC3

MSC4

OWN MSC

SPC:___

SPC:___SPC:___

SPC:___

SPC:___

Expanding the current network

by adding four new MSCs


IP trunk architecture


TGSU & IPET

TGSU

TGSU uses SIP with ISUP tunnelling as call control protocolOver IP. TGSU dynamically negotiates the media source anddestination IP addresses with SIP parameters in the beginningof each call setup.

IPET

IPET units can be associated with traditional ETs. IPET is afunctional unit which is implemented using a half of a PacketControl Unit (PCU)-A plug-in unit. IPET forwards the speechframes arriving from the switch matrix to the IP network.

Common Channel Signalling_ss7

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