Sgs n Training

For internal use1 © Nokia Siemens Networks SGSN Training Module Vikas Malhotra -26 Mar 2010

Serving GPRS Support Node (SGSN)


Agenda

GPRS Introduction – Duration 1 hourGSM Network architecture Circuit core vs Packet coreGPRS network elements

Overview of GPRS network architecture Brief functionality of all nodes

GPRS Traffic Management – Duration 2 hoursMobility Management in SGSN

LAC/ RAC overview Mobility management states GPRS location update call flows

Session Management in SGSN PDP Context activation PDP Context deactivation PDP Context modification

Charging Online Charging in SGSN Offline Charging in SGSN

Lawful Interception


Agenda

NSN SGSN Introduction – Duration 2 hoursSGSN Network InterfacesSGSN Hardware Architecture

Hardware modules overview Detailed functionality of each module Redundancy in various hardware modules

SGSN Logical Architecture Mapping of hardware modules with external interfaces Brief on interworking of various hardware modules

SGSN O&M Logging in SGSN Understanding SGSN CLI Most used commands Sample Configurations Examples of troubleshooting

Hands On Session – Duration 1 hours


GPRS Introduction - GSM Network architecture

The main elements of Network Switching Subsystem are:

Mobile Services Switching Centre (MSC) Visitor Location Register (VLR) Home Location Register (HLR)

The Base Station Subsystem consists of the following elements:

Base Station Controller (BSC) Base Transceiver Station (BTS) Transcoder (TC)


GPRS Introduction - Circuit core vs Packet core

Packet switched vs circuit switched

Circuit-switched connections are routed via MSC Packet-switched connections are routed via SGSN RAN part is shared between CS and PS traffic

IN SCP

GGSN

GSMmobil

e

UMTSmobil

e

GSM / UMTSmobil

e

GSM BTS

UMTS RANUMTS

BS

InternInternetet

(TCP/(TCP/IP)IP)

MSMSSS

HLHLRR

SRSRRR

GSM/GPRS BSS

BBSSCC

BBSSCC

GSM BTS

UMTS BS

RNRNCC

RNRNCC

Landline NWLandline NWPSTN/ISDNPSTN/ISDN

MGMGWW

SGSN

3G SGSN

GPRS GPRS BackbBackboneone

Network Network SubsystemSubsystem


Main SGSN functions

• mobility management

• session management

• charging (post-paid, prepaid)

• statistics

• 2G compression

• authentication

• 2G ciphering

• SMS handling


GPRS Network

HLR/AuCEIR

MSC/ VLR

SGSN

Gateway GPRSSupport Node(GGSN)

Lawful InterceptionGateway (LIG)

Datanetwork(Internet)

PSTNNetwork

SS7Network

Billing System

BSCBTS

Datanetwork(Internet)

DNS Domain name server

SGSN

Service Control Point (SCP)

RNC

NODE B

Border Gateway (BG)

GPRSbackbonenetwork

(IP based)

Inter-PLMN BB

Charging Gateway (CG)


GPRS Traffic Management - Mobility Management

LAC/ RAC overview

The relationship between Cell, RA, LA, and SGSN coverage area :

Cell Routing area Location area ⊂ ⊂ ⊂MSC coverage area

Cell Routing area SGSN coverage ⊂ ⊂area

RAI = MCC + MNC + LAC + RAC

Where RAC is Routing Area Code The RAI is LAI + RAC. The RAI is of fixed length - 15 digits.



Mobility management states:

Idle State Ready State Standby State

Idle StateStandby State

Ready State


STANDBY

IDLE

READY

Implicit detach Implicit detach or cancel or cancel locationlocation

GPRS AttachGPRS Attach

READY timer expiryREADY timer expiryORORForce to standbyForce to standbyORORAbnormal RLC Abnormal RLC conditioncondition

PDU receptionPDU reception

GPRS DetachGPRS DetachORORCancel LocationCancel Location



The procedures of Mobility Management are:

GPRS Attach/ GPRS Detach

Purge

Security Authentication subscriber identity confidentiality Ciphering (2G only) Identity check.

Location management

PS Paging

Normal/periodic routing area update.

Subscriber Management

Interaction with MSC/VLR

IMSI attach/detach, combined IMSI/GPRS attach/detach

Combined routing area and location area update

CS paging

Non-GPRS alert




GPRS Attach Procedure (MS Initiated)



GPRS Detach Procedure (MS Initiated)

GPRS Detach Procedure (HLR Initiated)


The MS is detached from GPRS either explicitly or implicitly:

• Explicit detachExplicit detach: The network or the MS explicitly requests detach specifying the cause for it

• Implicit detachImplicit detach: The network detaches the MS after the mobile reachable timer expired or after an irrecoverable radio error causes disconnection of the logical link

After a successful detach:– MM context and PDP context in PAPU are removed;

– P-TMSI - IMSI association is not removed from PAPU;

– The Visiting GPRS subscriber data may be deleted from SMMU;

– otherwise the data from SMMU is removed when "Detached subscriber storage time" timer expires. Also the IMSI-P-TMSI association from PAPU is removed and a "Purge" message is sent to HLR.



INACTIVE

ACTIVE

PDP context deactivation(the last) GPRS detach

PDP context activation

PDP context activationPDP context modificationPDP context deactivationTimer expiryResource reallocationPDU

INACTIVE

ACTIVE

PDP context deactivation(the last) GPRS detach

PDP context activation

PDP context activationPDP context modificationPDP context deactivationTimer expiryResource reallocationPDU

GPRS Traffic Management - Session Management


GPRS Traffic Management - Session Management

PDP Context Activation

PDP Context Modification

PDP Context Deactivation


Access Point Name

NOTE: The APN stored in the HLR does not contain the APN Operator Identifier. Also a wild card may be stored in the HLR instead of the APN.

APN Network Id APN Operator Id

my.isp.com. mncxxx.mccyyy.gprs

An Access Point Name is composed of two parts as follows:

The APN Network Identifier

The APN Operator Identifier

The APN Network Identifier is mandatory and is a label (for example "corporation") or a set of labels separated by dots which is a domain name according to the DNS naming conventions

The APN Operator Identifier is optional. It is a domain name according to the DNS naming conventions, and consists of three labels. The APN Operator Identifier shall end with ".gprs".

APN=


APN Selection

The SGSN selects the Access Point NameAccess Point Name (APN) to be used for a PDP context based on the MS-requested parameters and the subscribed PDP contexts of the user

The MS can request one of the combinations of the PDP type, PDP address, and APN parameters, which influence the APN selectionAPN selection:

– PDP type, PDP address, APN

– PDP type, PDP address

– PDP type, APN

– PDP type

– None of these parameters


GPRS Traffic Management - Charging

Offline Charging: S-CDRs M-CDRs SMS-CDRs

Online Charging: CAP3


Triggering for CDRs Generation

• Inter PAPU RA Updates are handled like Inter SGSN RA updates in S-CDR point of view• CDR data volume and CDR time limit are configurable parameters

*) If ‘Cell ID in S-CDR’ feature is used

Action Call Data Collection New CDR Subrecord CDR Ready for Transfer

(subscriber/network-generated) Start Stop S-CDR M-CDR S-CDR M-CDR

Attach M

Detach M X

Start of PDP Context S

End of PDP Context S X

Inter SGSN RA Update (old SGSN) M & S X X

Inter SGSN RA Update (new SGSN) M & S

Intra SGSN RA Update (Inter PAPU) S S X X

Cell update (Intra PAPU) X (*

O&M Request M & S X X

Time Tariff Category Switch X

Threshold Volume X

Threshold Time X X

QoS Change X

PAPU restart M & S X X


GPRS Traffic Management – Lawful Interception


NSN SGSN Introduction – SGSN Interfaces


NSN SGSN Introduction – Hardware Architecture

FRONT SIDE

CC4C-A

PAPU14

CC4C-A

PAPU15

CC4C-A

PAPU16

CC4C-A

PAPU8

CC4C-A

PAPU5

CC4C-A

PAPU4

CC4C-A

SMMU3

0 3 6 95

4

3

2

1

0

SGBC

CC4C-A

PAPU13

CC4C-A

PAPU10

CC4C-A

PAPU11

CC4C-A

PAPU12

CC4C-A

PAPU9

CC4C-A

PAPU6

CC4C-A

PAPU7

CC4C-A

SMMU4

CC4C-A

PAPU3

FTRB-A 2 FTRB-A 390 3 6

0 3 6 9

FTRB-A 0 FTRB-A 190 3 6

CL

AC

-BC

LB

U 4

, 5

CL

AC

-BC

LB

U 2

, 3

0 2 8 10

PDFU-BPDFU 0

PDFU-BPDFU 1

CC4C-A

PAPU0

CC4C-A

PAPU1

CC4C-A

PAPU2

CC4C-C

OMU1

CC4C-A

OMU0

CC4C-A

MCHU1

CL

AC

-BC

LB

U 0

,1

0 3 6 9

CC4C-A

SMMU0

1

CC4C-ASMMU

1

0 2 6 9

SD4C-ASD0OMUMCHU

SD4C-ASD 1OMUMCHU

5

4

3

2

1

0

FTRB-A 0 FTRB-A 10 3 6 9

FTRB-A 2 FTRB-A 30 6

0 10

SGAC

0

1

2

3

4

5

6

8

9

10

7CC4C-A

SMMU2

SW10C-A

GSW2KB1

LA

SW

C-A

LA

NU

0

LA

SW

C-A

LA

NU

1

6 83

CC4C-A

MCHU0

CC4C-A

MCHU0

CPRS-A

CPLC18

CPLAN-A

PDFU-BPDFU 0

PDFU-BPDFU 1

CPETS-E/CPETC-E

CPETS-E/CPETC-E

CPETS-E/CPETC-E

CPEA

CPETS-E/CPETC-E

CPETS-E/CPETC-E

GT4C-AGTIC 0ET16

(ETS2)

GT4C-AGTIC 1ET16

(ETS2)

CPLC18

CL

OC

-BC

LS

USW10C-A

GSW2KB0

SW10C-A

GSW2KB0

CPBP

BASIC CABINET EXTENSION CABINET

SGSN Hardware Units: Packet Processing Unit (PAPU)

process user data and protocol conversion GPRS mobility management (GMM) session management (SM) ciphering and compression between the MS and SGSN Up to 16 + 1 PAPUs

Signalling and Mobility Management Unit (SMMU)

support subscriber mobility management SS7-based interfaces Gr, Gd, Gs, and Gf Up to 4 + 1 SMMU

Operation and Maintenance Unit (OMU) traffic control functions maintenance, system configuration administration, and system management

Marker and Charging Unit (MCHU) collects and stores charging information controls and supervises the group switch (GSW) hunts free circuits establishing and releasing connections

Group Switch (GSW) – Connect to BSS/ NSS Exchange Terminal (ET) – Connect Transmission to GSW Message Bus (MB) – Interconnect Cards


NSN SGSN Introduction – Logical Architecture

The main units supporting GPRS are PAPU and SMMU.

The SMMU and PAPU have N+1 redundancy, whereas the MCHU, OMU, MB, GSW and CLS have 2N redundancy


Signalling and Mobility Management Unit - SMMU (1/2)

SMMU supports subscriber mobility managementsubscriber mobility management functionality. For this it uses several SS7–based interfaces that connect the SGSN to various NSS network elements

SMMU manages a visiting GPRS subscriber database (GSBASE)One SMMU can handle 750.000750.000 subscriberssubscribers simultaneously

-slot 1: PSC6-CB Power Supply

-slot 2: AS7C CCS7 interface unit

-slot 3/4: CP816-AC Central Processing Unit

-slot 5: PSC6 Power Supply

-slot 6: AS7C CCS7 interface unit

-slot 7: CP816-AC Central Processing Unit

1 2 4 5 6 73

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

CP

U

ETx1

ERx1

AS

7

AP

OP R

ON

OFF

PS

C6-

CB

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

CP

U

ETx1

ERx1

OP R

ON

OFF

PS

C6-

CB

AS

7

AP

5

4

3

2

1

0

SGBC

FTRB-A 2 FTRB-A 3

FTRB-A 0 FTRB-A 1

5

4

3

2

1

0

FTRB-A 2 FTRB-A 3

SGAC

CC4C-A

MCHU0

CL

SU

LA

NU

0

LA

NU

1

MCHU

1

MCHU

0

FTRB-A 0 FTRB-A 1

CL

BU

OMU

1OMU

0

PAPU

1PAPU

0

SM

MU

0

SM

MU

1

SM

MU

2

SM

MU

3

PAPU

6

PAPU

2

0

SM

MU

4

SM

MU

5

GS

W2K

-1

GS

W2K

-0

PAPU PAPU PAPU3 4 5

ET16 ET16

(ETS2 (ETS2

1

2

3

4

5

6

7

8

9

10

PAPU

7

CL

BU

PAPU PAPU

PAPU PAPU PAPU PAPU

PAPU PAPU PAPU

8 9

10 11 12 13

14 15 16

PDFU 0 PDFU 0PDFU 1 PDFU 1


SMMU can handle up to 64 CCS7 linksup to 64 CCS7 links

Support for SS7oIP (SIGTRAN)

N+1 Redundancy

Up to 6 SMMU in SGSN

Signalling and Mobility Management Unit – SMMU (2/2)

1 2 4 5 6 73

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

CP

U

ETx1

ERx1

AS

7

AP

OP R

ON

OFF

PS

C6-

CB

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

CP

U

ETx1

ERx1

OP R

ON

OFF

PS

C6-

CB

AS

7

AP


Packet Processing Unit - PAPU (1/4)

• The main purpose of PAPU is to process the user data to/from the RAN and relay it from/to the GPRS backbone network.

• Also handles session and mobility management functions

5

4

3

2

1

0

SGBC

FTRB-A 2 FTRB-A 3

FTRB-A 0 FTRB-A 1

5

4

3

2

1

0

FTRB-A 2 FTRB-A 3

SGAC

CC4C-A

MCHU0

CL

SU

LA

NU

0

LA

NU

1

MCHU

1

MCHU

0

FTRB-A 0 FTRB-A 1

CL

BU

OMU

1

OMU

0

PAPU

1

PAPU

0

SM

MU

0

SM

MU

1

SM

MU

2

SM

MU

3

PAPU

6

PAPU

2

0

SM

MU

4

SM

MU

5

GS

W2K

-1

GS

W2K

-0

PAPU PAPU PAPU

3 4 5

ET16 ET16

(ETS2 (ETS2

1

2

3

4

5

6

7

8

9

10

PAPU

7

CL

BU

PAPU PAPU

PAPU PAPU PAPU PAPU

PAPU PAPU PAPU

8 9

10 11 12 13

14 15 16

PDFU 0 PDFU 0PDFU 1 PDFU 1



1 2 4 5 6 73

OP R

ON

OFF

PS

C 6

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

CP

U

ETx1

ERx1

IOC

P-E

A

AS

7

AP

AS

7

AP

1 2 4 5 6 73

OPR

ON

OFF

PS

C 6

ES

B26

0

CP

U

AS

7

IOC

P

AS

7

AS

7

- slot 1: PSC6 Power supply

- slot 2: AS7-C

IOCP -E Central Processing Unit

for I/O Interface Unit

- slot 5: AS7-C Frame Relay Unit


- slot 7: CP816 -A Central Processing Unit

Frame Relay Unit

- slot 3/4:

- slot 1: PSC6 Power Supply - slot 2-4: IOCP-EA Central Processing Unit

for I/O Interface Unit


- slot 6: AS7-C Frame Relay Unit- slot 7: CPU Central Processing Unit

PAPU with IOCP-E PAPU with IOCP-EA



In order to carry the user data between the RAN (Gb or Iu) and the Backbone (Gn), PAPU needs to support a large set of protocols:

Relay

GTP

UDP

IP

Ethernet

SNDCPLLC

BSSGPNS cntl

FRE1Gb/FR (BSS) Gn (GGSN)

PAPU

2G : Gb/FR

Relay

GTP

UDP

IP

Ethernet

SNDCPLLC

BSSGPNS cntl

UDP/IPEthernetGb/IP (BSS)

Gn (GGSN)

PAPU

2G : Gb/IP

Relay

GTP

UDP

IP

Ethernet

SNDCPLLC

BSSGPNS cntl

FRE1Gb/FR (BSS) Gn (GGSN)

PAPU

2G : Gb/FR

Relay

GTP

UDP

IP

Ethernet

SNDCPLLC

BSSGPNS cntl

UDP/IPEthernetGb/IP (BSS)

Gn (GGSN)

PAPU

2G : Gb/IP

Relay

GTP

UDP

IP

Ethernet

Iu user (RAN) Gn (GGSN)

IOCP-E or IOCP-EA

3G: Iu User Plane

GTP

UDP

IPEthernet

Ethernet

PAPU CPU

IPSCTP

M3uA

RANAP

SCCP

Iu control (RAN)

ATM

MTP-3b

ATM relay to IOCP-EA

3G: Iu Control Plane



One AS7-CAS7-C can handle up to 256 tslsup to 256 tsls at 64kbit/s for frame relay frame relay connectionconnection;

IOCP-EIOCP-E contains 4 Ethernet interfaces4 Ethernet interfaces: 2 Ethernet connections for the Gn interfaceGn interface and 2 Ethernet connections for the Iu interface over IPIu interface over IP (optional). IOCP-EAIOCP-EA adds 4x155Mbps Fibre ATM interfaces

CPU816-ACPU816-A also contains 4 Ethernet interfaces4 Ethernet interfaces: 2 Ethernet connections for the Gb interface over IPGb interface over IP and 2 Ethernet connections for EMB EMB interfacesinterfaces

Can manage up to 100 000 subscribers 100 000 subscribers in High Traffic mode or 250.000 250.000 subscribers subscribers in High Attach mode.

A standalone PAPU serves maximum 1000 RA

N+1 Redundancy (IOCP-E) or N+ redundancy (IOCP-EA)

Up to 17 PAPUs in SGSN


IOCP-E plug-in unit performs CIPHERING and COMPRESSION

2G CIPHERING

In GPRS, both user data and signalling are ciphered all the way between the MS and the SGSN, not between the MS and the BTS.

2G COMPRESSION

Used between SGSN and MS to minimize the usage of radio and BSS transmission resources, and to speed up the user perceived data throughput.

IOCP-E can perform two kinds of compression:

HEADER COMPRESSION

USER DATA COMPRESSION

EA-variant includes 4x155Mbps ATM interfaces

Central Processing Unit for I/O Interface – IOCP-E/EA


Interface capacity

• A maximum of 512 bearer channels per PAPU and maximum of 3072 bearer channels per SGSN towards 2G RAN(Gb).

• A maximum of 64 SS7 signalling links per SMMU and maximum of 320 SS7 signalling links (Gr, Gd, Gf and Gs) with 5 SMMU per SGSN, HW supports that number but SW may bring restrictions.

• A maximum of 240 physical E1/T1 PCM lines (Gb and all SS7-based interfaces).

• A maximum of 256 RACs (with or without Multipoint) per SGSN


Capacity licence management

SGSN element level subscriber, PDP context, and data throughput capacity control are handled with licence management

A valid licence for SGSN level subscriber capacity, PDP context capacity, and data throughput capacity is needed. The following feature codes are in use:

– SGSN Total Attach Capacity

– SGSN Gb Attach Capacity

– SGSN Iu Attach Capacity

– SGSN PDP Context Capacity

– SGSN Data Throughput Capacity


NSN SGSN Introduction – O & M

Logging in SGSN



Logging in SGSN



Logging in SGSN



Understanding SGSN CLI



Subscriber Management Commands

Command DescriptionZMMO Check subscriber statusZMMS Check subscriber profile (subscribed APNs)ZMMN Display Number of subscribersZMMD Delete subscriber from SGSN

Command DescriptionZFWO Check GB link statusZEJL Check BVCI statusZW7I Check Licence installed (used for BVCI Count)ZQRI Check IP configurationsZAHO Check system alarmsZQRX Ping/ Traceroute for any interfaceZWVI Check GT/ MNC/ MCC details for own SGSNZWQO BackupZGHI Check Charging Gateway Status

Command DescriptionZOYI Check SCTP association set statusZCFI Check IMSI to GT analysisZNBI Check GT analysisZNAI Check GT Translation resultsZNHI Check Subsystem States

General Health Check and O&M Commands

SS7 Signaling Management Commands



Sample Configurations – Gb Link



Sample Configurations – PLMN Configuration



Sample Configurations – IMSI To GT Table



Sample Configurations – LAC Configuration



Sample Configurations – Signaling Link status



Sample Configurations – Check Unit Load



Sample Configurations – Checking System Clock


NSN SGSN Introduction – Analysing Traces









Examples of troubleshooting

Gb Link Trouble shooting Ping Remote IP Take traceroute Get configurations checked at both SGSN and BSC ends Check for any information in alarms PAPU Switchover

GPRS not working Check if subscriber is attached in SGSN Check APNs allowed for subscriber Verify APN subscriber is using for Data Call Take trace on Gn and Gb interfaces

Subscriber not getting attached Check IMSI to GT analysis Check GTT Take trace on Gb and Gr interfaces

Ga, Gn interfaces trouble shooting Ping GGSN/ Charging Gateway IP Take traceroute Take trace on Gn interface


Hands On Session


Q & A


Thank you

Documents

Sgs n Training