GPRS Overview

2

General Packet Radio Service (GPRS) - Background

> General Packet Radio Service (GPRS) is an extension of the popular GSM mobile standard that offers packet data to a mobile user.

> Before GPRS, data service on a GSM network was generally limited to 9.6 kilobits per second.

> GSM Circuit switch data utilized a full rate voice channel (Timeslot) on the air interface for the entire duration of the data connection whether or not data is being transferred. These connections are normally billed according to airtime.

> GPRS uses virtual connections for multiple users. Scarce radio resources are only allocated to a mobile if there is data waiting to be sent or received. As a result GPRS connections can be left ‘always on’ and are normally billed by data volume rather than time.

3

GPRS network overlaid on GSM network

•Support of GPRS does not represent a major upgrade to the existing GSM infrastructure. Largest impact is the addition of SGSN, GGSN, and PCUSN•The main functions of SGSN are: to detect and record GPRS MS in its service area, send/receive data packets to/from the MS.•The main function of GGSN is to forward data packets between the Public Data Network (PDN) and a GSM PLMN. •In addition to routing and data transfer functions, the SGSNs and GGSNs collect charging statistics that are commonly used as a basis for billing

4

GPRS Packet Data Service

In GPRS some timeslots are dedicated to providing packet data service. The Packet Control Unit Support Node (PCUSN) controls the fair allocation of GPRS radio resources in real-time.

If there are multiple users in the cell they can share different data frames on the same timeslot. This arrangement works great with bursty data like web browsing. Data resources on the uplink and downlink are allocated independently. Throughput for a user depends on the number of GPRS timeslots and the amount of resource requested.

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Mobile Network

(GPRS)

RadioRadio

TS 2TS 2

TS 1TS 1

TS 3TS 3

TS 4TS 4

TS 5TS 5

TS 4TS 4 TS 5TS 5

5

GPRS Packet Data Service – Contd.

> Three Users Sharing One TS

traffic on the link

User A

User B User C

time

GPRS well adapted for bursty and interactive applications

Less blocking Higher rates

One radio channel

for several users

Time Slots are shared

One user utilizes

several radio channels

Time Slots are aggregated

6

GPRS Applications > Personal Messaging: e-mail, schedule update

> Mobile office: internet e-mail, file transfer, database access

> E-Commerce: interactive shopping, ticket sales, interactive banking and gambling

> On-line information access: news, web browsing, directory service, yellow pages, traffic information, train/plane time table, stock prices, real estate information

> SMS• SMS can be offered with ‘web’ like interface• GPRS terminals make composing and reading messages easy

> Telemetry: Simple Messaging - Remote monitoring and reporting of metering devices such as:• electric, gas and water meters • vending machines• car rental, taxis• bank teller machines

7

Network Architecture

PSPDN

A

PSTN/ISDN

Agprs

Gr

Gs

Gc

Gn

GGSN

Gb

Ater

BTS

SMSC

Gd

Gp

SGSN ofother PLMN

HLREIR

Gf

BSC

TCU

Gi

SGSNPCUSN

GaGa

CGF

MSC-VLR

8

Backbones Used

Frame Relay Network

PCUSNs

GbGb

BSCs

Agprs BSCsAgprs

Agprs

Agprs

Intranets

SGSNs

Gi

Gi

Gn

Gn

Gn

Gn

Gn

GGSNs

IP BackboneGn

Internet

SS7 Network

Existing GSM

Components

SGSNs

SIG

9

Nortel Implementation

SGSN of other PLMN

PSPDN

A

PSTN/ISDN

Agprs

Gs

Gn

GGSN

Gb

Ater

BTS

GpBSC

TCU

Gi

SGSNPCUSN

Ga

GaCGF

MSC-VLR

Gr

GeSMSC

GdLEA

LiG

Lh

HLR External LCSClients

GMLCLg

Le

SIG

SCP

Section 2:Functions of the GPRS Elements

11

Packet Control Unit Support Node (PCUSN) functions

BSC

RLC/MAC Block Management

Gbasynchronous

BSSGP Flow ControlFrame Relay Links

Agprssynchronous

PCUSN

MS

SGSN

Main function of the PCUSN is to provide the interworking function between two interfaces

•Packetized radio interface Agrs•Packet network interface Gb•Nortel Solution - PCUSN is introduced as a separate node in the BSS in order to provide the PCU functionality. This functionality is hosted on the Passport platform

12

Signaling Gateway Support Node (SGSN) functions

DNS

PCUSN

GGSN

MS

Routing Resolution

Gr

Mob ManagementBilling Records

Ga

GnGTP Tunneling

Ciphering &

Compressio

n

GbFra

me

rela

y

LICP

Lo

cation

Services

LIG

GMLCCGF

HLR

SGSN

SGSN is hosted on the Passport platform.

SGSN performs: Mobility management, routes packet data, authentication, encryption, compression

Mobility management performs: Session management, MS state control (ready, standby, or idle), data packet routing on the downlink, including location tracking.

SGSN performs authentication and ciphering procedures based on the same algorithms, keys and criteria as in existing GSM, but the ciphering algorithm is optimized for packet data transmission.

13

GPRS Gateway Support Node (GGSN) functions

DHCP

GGSN

Intranet

Intranet Switch

Gn

GTP Tunneling

SGSN

ChargingGatewayFunction

VPN Tunneling

Gi

IP address Management Billi

ng Records

Ga

Authentication Radius

•GGSN serves as the interconnect point between the SGSN and the external PDN•Routing•Tunneling – Two way point to point path to transfer encapsulated data•Security•Mobile subscriber authentication – Radius server•IP address allocation – Internal pool or DHCP•GGSN accounting - CGF

•Provides secure communication between GPRS users and the IP world in addition to providing tunneling capabilities within the GPRS network system itself. •GGSN is hosted in the Shasta 5000 BSN

•For UL packets from the MS, GGSN strips off the GTP and lower layer headers and delivers the IP and X.25 packet in its native form to the external network. •For DL packets to the MS, GGSN performs the opposite operation: it adds GTP and lower layer headers

14

SS7/IP Gateway (SIG) Functions

SIG

Gr

GsIP

Backbone

HLR

MCS/VLRGdGe

SCP

Lg

GMLC

SS7 Network

SGSN1

SGSN2SMSC

•The Hewlett-Packard SS7/IP Gateway server (duplex ) or HP SIG provides inter-working between GPRS nodes in an IP network and GSM nodes in an SS7 network •SIG is responsible for routing messages from the GSM HLR to the correct SGSN

•Converts TCAP/GSM MAP encoded messages originating from the GSM HLR in the SS7 network, to UDP/IP messages containing the GSM MAP Client interface for GSM messages destined for the GPRS SGSN nodes

•It performs the reverse for messages which are originated by the SGSN and destined for the HLR

15

Domain Name Server (DNS) Functions

Internet

DNS

End user enters the URL:http://www.nortel.com

www.nortelnetworks.com

(136.147.68.68)

(1) What is the IP address of

www.nortelnetworks.com?

(2) 136.147.68.68(3) 1

36.1

47.6

8.68

•Domain Name Server is a distributed Internet/Intranet directory service, translating domain Names to IP addresses and vice versa

•The lists of Domain Names are distributed over the Internet

16

Dynamic Host Configuration Protocol (DHCP) Functions

GPRS Network

(1) I need an IP

address

(4) Use th

is address:

136.147.102.26

SGSN

Internet

GGSN

This will be my address:136.147.102.26

IP Backbone

DHCP(2

) E

nd

use

r n

eed

s IP

ad

dre

ss

(3)

Giv

e th

e en

d u

ser

this

on

e:13

6.14

7.10

2.26

DHCP reduces the administrative burden of manually configuring computers for network use

17

Remote Authentication Dial-In User Service (RADIUS) Functions

FrameRelay

Network

IP Backbone

MS

Is this alegitimate user?

RADIUS server

SGSNSGSN

GGSNGGSN

Log-in, Password

Authenticates remote users and performs accounting functions

18

Charging Gateway Function (CGF) Functions

Corenetwork

SGSN

Aggregator&

Distributor

CGF

Billing FilesTransfer

Billing Center

Get billing files

G-CDR

GGSN

S-CDR and M-CDR

Collector

GTP’

GTP

Billing Records:• PDP session duration• GPRS QoS Negotiated• Input Octets• Output Octets• Hot Billing

The CGF is responsible for aggregating and sorting billing records and then translating them into a

format that is useable by the downstream billing system .

19

HLRGr (SS7)

Home Location Register (HLR) Functions

Gr’ (IP)

• SGSN sends MAP messages over Gr’ to SIG. The SIG then sends this over SS7 to the HLR.

• The HLR is queried by the SGSN to verify subscription to the network and to retrieve the mobile’s subscription records (GPRS services, APN, QOS etc.).

• The HLR keeps track of what SGSN the mobile is currently attached to.

HLRGr (SS7)

Gr’ (IP)SIG

SGSN

20

Visiting Location Register (VLR) Functions

• SGSN sends BSSAP+ messages over Gs’ to SIG. The SIG then sends this over SS7 to the VLR.

• The MSC/VLR notified by the SGSN when a mobile is attached for circuit service.

• The VLR keeps track of what SGSN the mobile is currently residing within and can use this information to page the mobile for circuit services.

MSC/VLRGs (SS7)

Gs’ (IP)SIG

SGSN

21

Signaling Control Point (SCP) Functions

• SGSN sends CAMEL messages over Ge’ to SIG. The SIG then sends this over SS7 to the SCP.

• The SCP is notified by the SGSN when a mobile is activate and requires CAMEL services.

• The SCP is used for pre-paid service. It keeps track of a resource and lets the SGSN know when no more resources are available. The common example is to limit the amount of data traffic for a given mobile.

SCPGe (SS7)

Ge’ (IP)SIG

SGSN

22

Short Message Service Center (SMSC)

• SGSN sends SMS messages over Gd’ to SIG. The SIG then sends this over SS7 to the SMSC.

• For SMS, the SGSN sends SMs to the SMSC for a mobile initiated SMS.

• For SMS, the SMSC sends SMs to the SGSN for a mobile terminated SMS.

SMSCGd (SS7)

Gd’ (IP)

SIG

SGSN

Section 2:Signaling GPRS Support Node

24

The Passport is used to provide the Serving GPRS Support Node (SGSN) for GPRS

The Passport family of switches can support a wide variety of services from ATM, frame relay, IP routing, circuit emulation and voice services. A highly scalable and modular platform, the Passport can be configured to support multiple services and provides the ability to upgrade its hardware appropriately.

Passport

25

SGSN hardware

Example multi-shelf consists of :Passport 15000 Turbo (aka 15K) Passport 7480 Classic (aka 7K)

SGSN/MG/AN shelf for UMTS utilize the 15K shelf only.

BIP

SGSN FrameSGSN Frame

7K - Shelf7K - Shelf

CP

Exp

CP

CP

FP

FP

FP

FP

FP

IFP

CP

Exp

CP

CP

FP

FP

FP

FP

FP

IFP

15K - shelf15K - shelf

26

Processor Cards

Control Processor (CP) provides control and management of the switch and its FPs, performs memory-intensive, non-real-time tasks such as routing table maintenance. It also provides system timing for all other processors connected to the backplane.

Function processors (FP) provide the communication physical interfaces for Passport trunks or access services, real-time processing, packet routing and protocol handling.

27

Passport Backplane

Bus backplane The backplane of the Passport 6000/7000 series consists of two fully duplicated, load-shared 800 Mbit/s buses. If one bus fails, all the communication shifts to the working bus. Passport cells sent to any bus are seen by all processor cards, but all cards except the one the cell is destined for will discard it.

Fabric backplane The backplane of the Passport 15000 consists of two fabric cards connecting processor cards in a full mesh configuration. If one fabric card fails, the other fabric card can operate solely at full shelf capacity. The fabric cards contain a switching element that routes backplane cells to the appropriate processor card. Switching capacity of 40Gbit/s.

28

GPRS/UMTS SGSN Functional Card Types

CP (Control Processor)

> Passport control

GTL (GPRS Transport Layer)

> Gb Interface transport (Frame Relay)

GSC/USC (GPRS/UMTS Subscriber Control)

> Data signaling traffic

> Mobility and session management

> HLR-cache and DNS agent, MapClient

GSD/USD (GPRS/UMTS Subscriber Data Layer)

> Data bearer traffic

> Ciphering/Deciphering, Compression, Segmentation

Ethernet/ATM Card

> connectivity for various interfaces

SAS (Service Accounting Server)/LI (Lawful Intercept)

> SGSN billing functionality

> Lawful Intercept functionality

TCAP/MAP (Transaction Capability/Mobile Application Part)

> Inter-working with SS7 to IP Gateway

29

Example SGSN Configuration

LA

N

E0 0 1 2 3 4 5 6 7

CP

GSC

CP

GSD

OC

3

OC

3

OC

3

CP

GSC

SAS

SAS

MAP

MAP

ATM 4POC3

One OC3 Link to Each OC3 FP on 7K shelf

To GGSN &SIG

ETHER

ETHER

Optional EthernetTo GGSN &

SIG

E1/DS1 to PCUSN

GSD

GSD

GSD

GSD

GSD

CP

GSC

ATM 4POC3

GTL

GTL

GTL

GTL

GTL

GTL

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

30

Redundancy

The Passport 15000 and 7000 Platforms and Function Processors (FPs) offer a variety of redundancy options to ensure the availability of services and sessions over various failure scenarios.

CP Redundancy

In a 7K redundant arrangement CPs are placed in slot 0 and slot 15. In a 15K Passport the CPs are placed in slot 0 and 1. The redundant CP operates in warm standby state. The standby CP becomes active when it detects the active CP has failed, assuming both active and standby CPs are synched.

31

GSC/USC Redundancy

All the function processors can be provisioned in N+1 load sharing mode (i.e. dimensioning is carried over N cards, to provision N+1). The GSC/USC is N+1 over provisioned. Upon failure of one GSC/USC, an in service GSC/USC should handle all new requests.

• All Mobility management, session management data and sessions are lost. Users must reattach and reactivate to the network (manual intervention).

• Partial billing record loss.

• If GSC/USC does not recover or is locked, traffic will be distributed to remaining in service GSC/USC cards.

32

GSD/USD Redundancy

The GSD/USD is N+1 over provisioned. Upon failure of a GSD/USD, the remaining in service GSD/USD’s handle all new requests.

• Subscriber data context information lost. User reactivates session (manual intervention) or Session Deactivate message received to force mobile to reactivate (no manual intervention).

• Data passing through and billing counts (uplink/downlink packets) will be lost.

• If GSD/USD does not recover or is locked, traffic will be distributed to remaining in service GSD/USD cards.

33

TCAP/MAP Redundancy

The TCAP/MAP card is 1:1 cold standby spared. Upon failure of the main TCAP/MAP, the spared TCAP/MAP card will handle all new requests .

• Delay to mobility management and SMS services.

• If both TCAP/MAP cards fail or are locked, complete outage for new subscribers attaching and SMS service.

34

SAS/LI Redundancy

The SAS/LI card is 1:1 cold standby spared. Upon failure of the main SAS/LI card, the spared SAS/LI card will handle all new requests. Switchover from main to spare card occurs.

• Portion of the partial record still on SAS is lost, closed CDR’s still on disk are lost without a maintenance activity for existing subscribers.

• Potential loss of SGSN billing records during switchover (mobiles that attach or activate during switchover will not be charged)

• If both SAS cards fail or are locked, new subscribers will not be billed.

35

GPRS GTL RedundancyThe GTL utilizes 2N load sharing, MSA cards are deployed in pairs

and at any time all 2N cards are active; with throughput redundancy, each card must be engineered at 40%. Upon failure of the primary GTL, the mated GTL will handle all new requests for redundant NSEs.

• No impact to the end user.

• Links are redundant, unless engineered at 40% significant capacity will be lost.

• If both the primary and mate GTL card fail or are locked, a complete outage will result for Network Service Entities solely served by these GTL cards.

36

ATM Redundancy

The ATM is 2N spared (inter-shelf communication). Upon failure of the ATM card, the alternate ATM card will handle all new requests.

• No impact to end user.

• If both ATM cards fail or are locked, inter-shelf communication is lost. Network outage will result.

Section 3:GPRS Gateway Support Node

38

Introduction> What is a GGSN?

• Gateway GPRS Support Node - A packet processing node in the wireless packet network, it serves as the boundary between the wireless network and other public or private networks.

> Nortel GGSN provides following configurable services:• Mobile subscriber authentication ( Remote Authentication Dial-In User

Service - RADIUS authentication• IP address allocation ( Dynamic Host Configuration Protocol (DHCP) address

allocation, RADIUS address allocation, Local address pool)• Outbound Tunneling ( L2TP, L2TP over IPSec, IPSec, GRE, VPN )• Accounting ( GTP Accounting, G-CDR Auditing, Tariff Based Billing (Time of

Day billing), RADIUS Accounting, Content Based Billing )• OA&M ( Operational Measurements, Event Logs, Alarms, Command Line

Interface (CLI), Patching )• Wireless Services ( GGSN QoS, Prepaid ), Wireless Application Protocol

(WAP) )• IP Routing ( OSPF, RIP, BGP, IS-IS, IP Multicast )

39

GGSN Interworking Requirements

GnGb Gi

Gp

Gf

Gc

GdE C

GsGr

SM-SCSM-SC

BSSBSS

Um

OtherOtherPLMNPLMN

GGSNGGSN

GGSNGGSN

EIREIR

SMS-GMSCSMS-GMSCSMS-IWMSCSMS-IWMSC

SGSNSGSN

HLRHLR

MSC/VLRMSC/VLR

SGSNSGSN

A

Gn

D

Public Data Public Data NetworkNetwork

CGF

Ga

40

GGSN Hardware

41

Hardware Description (1)

Gn, Gi & Gp interfacesGn, Gi & Gp interfaces• 4 port ATM STM-1 / OC-3, single

mode and multi mode fiber• 8 port Fast Ethernet• 3 port ATM E3/T3 + 1 port ATM

STM-1/OC-3, single mode and multi mode fibercan be used also for interface to a WAP Server

Interface to DHCP, RADIUS, CGF Interface to DHCP, RADIUS, CGF and SCPand SCP

• 2 port 10/100BaseT Ethernet on CMC card

Maximum of 4 Gigabit Ethernet cards, 8 port Fast Ethernet cards.

Chassis:Chassis:

– 14 slots

– 2 Control management cards (CMC)

– 2 Switch fabric card (SFC)

– 10 remaining slots with– Up to 6 Subscriber Service Cards (SSC)– Up to 10 Line Cards

– W: 19” -- H: 19.25” -- D:18”Packet ProcessingPacket Processing– Up to 96 CPUs on SSCs– Up to 42,000 MIPSFully redundant and Hot Fully redundant and Hot SwappableSwappable– NEBS 3 compliant– Full Hot Swap– DC/AC power

42

Hardware Description (2)

1 14

Remaining 10 slots (Slot1-6,9-12):- Subscriber Service Cards (SSCs)

- Line Cards (LC)

N+1 redundancy

Slot 13 & 14: Control Management Cards (CMC)

Slots 14 (primary) and slot 13 (back-up)

Responsible for:

- basic operation and management

- assignment of subscribers to the processor cards

- IP routing: RIP, OSPF.

- GGSN Accounting

- GTP Control Path

Slot 7 & 8: Switch Fabric Card (SFC)Provide the ATM layer interconnection and queuing between the various line cards and the SSC cards

1+1 redundancy (backup does not pass traffic)

Slot 5 & 6 or Slot 9 & 10:

Capable of 1.2 Gbps operation

8xFE, GE.

other slots capable of 622Mbps operation

other Line cards

Fan Assembly

43

System Architecture

10/100 Ethernet Server Ports

SSC- 6SSC- 1 SSC- 2 SSC- 3

......

CMC-A

Switching FabricSwitching FabricATM Switching Fabric Card (SFC)

Line Cards

4 x SubscriberService Modules (SSM) per SSC

Modular:5 Gbps10 Gbps

Subscriber Service Card (SSC)

ControlManagementCard (CMC)

4 x Processors &HW Encryption per SSMField Upgradeable

1

44

Responsible for basic system operation and management, assignment of subscriber to SSCs, IP routing, Accounting

Routing– CMC P1 runs the RIP or OSPF routing process – routing table used to populate the Forwarding Information Base (FIB), which

distributes reachability information to FIB caches on each SSM– The CMC assigns subscribers to SSM’s based on bandwidth allocation.

Modular Memory– Stores session information (PDP context and subscriber data)– 1 GB or 512 MB sync DRAM– 2 Meg L2 cache, 2xPower PC 750 processors, 233 MHz– Hard disk (4 GB ) used to store system configurations , log files and billing,

accounting files.

Control Management Card (CMC)

45

Ports supported• Two serial ports (RJ-45 connector) for console (text based

CLI for basic configuration) and modem• 1 x 10/100BASE-TX Ethernet port for OA&M• 2 x 10/100BASE-TX Ethernet ports for server and cache

connection (DHCP, RADIUS, CGF).

Flashcard slot (PCMCIA- II)

Control Management Card (CMC)

46

Switch Fabric Card (SFC)

Provides the ATM Layer interconnection and the queuing between the various line and processor cards

Alphanumeric display that provides information about card configuration and status.

Fabric is MMC-2000 chipset

5 / 10 Gbps totally non-blocking shared memory fabric• 10 Gbps All slots available• 5 Gbps Only slots 1, 2, 3, 4, 11, 12, 13, 14 available• Gigabit Ethernet and 8 port Fast Ethernet Line Cards only

available with 10 Gbps SFC (only slots 5, 6, 9, 10 support the appropriate bandwidth)

Note: the 8 x FE card can be placed in another slot but then only 4 port are available

47

Contains the processor arrays which perform the high touch services and policy services on a per subscriber basis

Up to 6 SSCs supported per chassis 5+1 (over provisioning) for maximum capacity

Highly scalable and flexible through support for up to 4 plug-in Subscriber Service Modules (SSMs)• SSM: 4 Subscriber Services Processor (SSP)

• SSP (Power PC 740) operates at 266 MHz and 256 Mb of local cache (no L2 cache) ??SSC: up to 16 SSPs GGSN: up to 96 SSPs

Subscriber Service Card (SSC) Subscriber Service Module (SSM)

48

• Provide physical connectivity in and out the GGSN

> Equipped with the Intelligent Cell Parser (ICP), that helps direct incoming traffic to the proper SSM.

The ICP receives configuration information as to subscriber identify from the CMC, and directs the traffic by intelligently parsing the first packet of a new flow (based on subscribers IP @s when coming from Gi side).

> Available for Gn, Gi and Gp interfaces:• 4 port ATM STM-1 / OC-3, single mode and multi mode fiber• 2 port OC-3 / STM 1 • 3 port ATM E3/T3 + 1 port ATM STM-1/OC-3, single mode and multi

mode fiber• 8 port Fast Ethernet• 1 port Gigabit Ethernet (card introduced in Shasta 2.5)

> Connectivity services:• ATM/AAL5• Ethernet

Note: 10/100BaseT Ethernet interfaces also available on the CMC cards for connections to DHCP, RADIUS and CGF servers, as well as to SCPs (Service Control Points)

Line Card

Section 4:Main GPRS Procedures

50

Functional MM State Model

of SGSN

Mobility management

READY

IDLE

STANDBY

GPRS Attach

GPRS Detachor

Cancel Location

PDU reception

READY timer expiryorForce to StandbyorAbnormal RLC condition

Implicit Detachor

Cancel Location

51

GPRS Attach Request

Update Location

Insert Sub Data

Insert Sub data Ack

Update Location AckGPRS Attach Accept

HLR

GPRS Attach Procedure

MS = READY

PCUSNSGSNMS

IMSI or ( P_TMSI + old RAI )

Attach type

MultiSlot capability

requested READY timer value

DRX parameters

P_TMSI

Negotiated ready timer value

Periodic RA timer

Security Functions ( Auth Request <-, Auth Response ->)

GPRS Attach complete

52

Activate PDP Context Request(NSAPI, PDP type, PDP address, QoS Requested,APN)

Security Functions

Create PDP Context Request

Create PDP Context Response

Tunnel

Activate PDP Context Accept(PDP type, PDP address, QoS Negotiated)

BSS

SGSN

GGSN

MS

Packet Data Protocol (PDP) Context Activation

> 1 - MS Initiated

(NSAPI, PDPtype, PDP@, QoS, APN)

(PDP address, QoS negociated)

DNS DHCP

53

Packet Data Protocol Context Activation

@ MS

Mobile Subscribed

PDP contexts

PDP Type: IPAPN: Nortel.com

PDP Type: IPAPN : Internet

PDP Type: X25APN: Transpac

10. @ M

S PDP context

activatio

n accept1. A

ctivate PDP Context A

PN

= Nortel.c

om

ISP

IntranetNortel.com

7. @

MS

6. @

: “

_ ”

GGSN X

DNS

DHCP

8. Start billing record

CGF

5. Tunnel Creation

GGSN Y

4. Create PD

P Context R

eq

9. Create PD

P Context

Accept (@

MS)

@ MS@ SGSN

SGSN@GGSN X

@ MS

3. @ GGSN X

2. Nortel.com.MNC.MCC.gprs

APN Operator Id

In this diagram, @ represents

“the IP address of”

54

MS-Initiated Detach Procedure

Detach Accept

Detach Request

Delete PDPContext Request

Delete PDPContext Response

BSS SGSN GGSN HLR

55

SGSN-Initiated Detach Procedure

Detach RequestDelete PDP

Context Request

Delete PDPContext Response

Detach Accept

BSS SGSN GGSN HLR

56

PDP Context DeactivationMS Initiated

Deactivate PDP Context Request

Security Functions

Deactivate PDP Context Response

Delete PDPContext Resp

Delete PDPContext Req

BSS SGSN GGSN HLR

57

PDP Context DeactivationNetwork Initiated

Deactivate PDP Context Request

Deactivate PDP Context ResponseDelete PDP

Context Resp

Delete PDPContext Req

BSS SGSN GGSN HLR

58

BSS SGSN GGSN HLR MSC/VLR

Modify PDP Context Request

Modify PDP Context Response

Update PDPContext Response

Update PDPContext Request

SABM

UA

PDP Context Modification Sequence MS Initiated

59

PDP Context Modification Sequence SGSN Initiated

BSS SGSN GGSN HLRMSC/VLR

Modify PDP Context Request

Modify PDP Context Response

Update PDPContext Response

Update PDPContext Request

ISD Ack

Insert Subsciber Data

SABM

UA

60

Security functionsAuthentication

BSS SGSN HLR

Attach Request

GPRS Auth Request

Send Auth Info

SAI Ack

GPRS Auth Response

RAND

A3

(IMSI, unknown CKSN) Ki(IMSI)

(Triplets , Kc)(RAND)

A3

Ki

(MS calculated SRES)

RANDSGSN

calculatedSRES

=

Yes

No ForbiddenSubscriber

Authentiicated Subscriber

61

Example: WEB Access

IDLE

READY

GPRS Attachment

MS

PDP ContextActivation

GGSN

WEBServer

Home Page Request

PCUSN

SGSN

62

Short Message Service (SMS)MS Originated

BSS SGSN SIG IWMSC

CP - Ack

CP - Data (RP - Data)

MOForward-ShortMessageAck

CP - Ack

CP - Data (RP - Ack)

MOForward-ShortMessage-

AckRsp

MOForward-ShortMessageReq MOForward-

ShortMessage

63

SMSMS Terminated

BSS SGSN SIG IWMSC

CP - Ack

CP - Data (RP - Data)

MTForward-ShortMessage

CP - Ack

CP - Data (RP - Ack)

MTForward-ShortMessage

MTForward-ShortMessage-

AckRsp MTForwardShortMessageAck

64

SMS PrepaidMS Originated

BSS SGSN IWMSC

CP - Ack

CP - Data (RP - Data)

MOForwardShortMessageAck

CP - Ack

CP - Data (RP - Ack)

MOForwardShort-MessageAckRsp

MOForward-ShortMessageReq

MOForwardShortMessage

SCP

PrePaid-CTP DecrementReq

PrePaid-CTP DecrementRsp

SIG