137889806-Sgs-n-Training

For internal use

1 © Nokia Siemens Networks SGSN Training Module Vikas Malhotra -26 Mar 2010

Serving GPRS Support Node (SGSN)

For internal use


Agenda

GPRS Introduction – Duration 1 hour GSM Network architecture

Circuit core vs Packet core

GPRS network elements

Overview of GPRS network architecture

Brief functionality of all nodes

GPRS Traffic Management – Duration 2 hours

Mobility 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

For internal use


Agenda

NSN SGSN Introduction – Duration 2 hours SGSN Network Interfaces

SGSN 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

For internal use


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)

For internal use


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

GSM

mobile

UMTS

mobile

GSM / UMTS

mobile

GSM BTS

UMTS RAN

UMTS BS

Internet

(TCP/IP)

MSS HLR

SRR

GSM/GPRS BSS

BSC

BSC

GSM BTS

UMTS BS

RNC

RNC

Landline NW PSTN/ISDN

MGW

SGSN

3G SGSN

GPRS Backbo

ne

Network Subsystem

For internal use


Main SGSN functions

• mobility management

• session management

• charging (post-paid, prepaid)

• statistics

• 2G compression

• authentication

• 2G ciphering

• SMS handling

For internal use


GPRS Network

HLR/AuC EIR

MSC/ VLR

SGSN

Gateway GPRS Support Node (GGSN)

Lawful Interception Gateway (LIG)

Data network (Internet)

PSTN Network

SS7 Network

Billing System

BSC BTS

Data network (Internet)

DNS Domain name server

SGSN

Service Control Point (SCP)

RNC

NODE B

Border Gateway (BG)

GPRS backbone network

(IP based)

Inter- PLMN BB

Charging Gateway (CG)

For internal use


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.

For internal use



Mobility management states:

Idle State

Ready State

Standby State

Idle State

Standby State

Ready State

For internal use


STANDBY

IDLE

READY

Implicit detach or cancel location

GPRS Attach

READY timer expiry OR Force to standby OR Abnormal RLC condition

PDU reception

GPRS Detach OR Cancel Location


For internal use


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


For internal use



GPRS Attach Procedure (MS Initiated)

For internal use



GPRS Detach Procedure

(MS Initiated)

GPRS Detach Procedure

(HLR Initiated)

For internal use


The MS is detached from GPRS either explicitly or implicitly:

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

• Implicit 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.


For internal use


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

For internal use


GPRS Traffic Management - Session Management

PDP Context Activation

PDP Context Modification

PDP Context Deactivation

For internal use


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=

For internal use


APN Selection

The SGSN selects the Access 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 selection:

– PDP type, PDP address, APN

– PDP type, PDP address

– PDP type, APN

– PDP type

– None of these parameters

For internal use


GPRS Traffic Management - Charging

Offline Charging:

S-CDRs

M-CDRs

SMS-CDRs

Online Charging:

CAP3

For internal use


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/netw ork-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 Sw itch X

Threshold Volume X

Threshold Time X X

QoS Change X

PAPU restart M & S X X

For internal use


GPRS Traffic Management – Lawful Interception

For internal use


NSN SGSN Introduction – SGSN Interfaces

For internal use


NSN SGSN Introduction – Hardware Architecture

FRONT SIDE

CC4C-A

PAPU 14

CC4C-A

PAPU 15

CC4C-A

PAPU 16

CC4C-A

PAPU 8

CC4C-A

PAPU 5

CC4C-A

PAPU 4

CC4C-A

SMMU 3

0 3 6 9 5

4

3

2

1

0

SGBC

CC4C-A

PAPU 13

CC4C-A

PAPU 10

CC4C-A

PAPU 11

CC4C-A

PAPU 12

CC4C-A

PAPU 9

CC4C-A

PAPU 6

CC4C-A

PAPU 7

CC4C-A

SMMU 4

CC4C-A

PAPU 3

FTRB-A 2 FTRB-A 3 9 0 3 6

0 3 6 9


0 2 8 10

PDFU-B PDFU 0

PDFU-B PDFU 1

CC4C-A

PAPU 0

CC4C-A

PAPU 1

CC4C-A

PAPU 2

CC4C-C

OMU 1

CC4C-A

OMU 0

CC4C-A

MCHU 1

0 3 6 9

CC4C-A

SMMU 0

1

CC4C

-A SMMU

1

0 2 6 9

SD4C-A SD0 OMU MCHU

SD4C-A SD 1 OMU MCHU

5

4

3

2

1

0


FTRB-A 2 FTRB-A 3 0 6

0 10

SGAC

0

1

2

3

4

5

6

8

9

10

7 CC4C-A

SMMU 2

SW10C-A

GSW2KB 1

6 8 3

CC4C-A

MCHU 0

CC4C-A

MCHU 0

CPRS-A

CPLC18

CPLAN-A

PDFU-B PDFU 0

PDFU-B PDFU 1

CPETS-E/ CPETC-E

CPETS-E/ CPETC-E

CPETS-E/ CPETC-E

CPEA

CPETS-E/ CPETC-E

CPETS-E/ CPETC-E

GT4C-A GTIC 0 ET16

(ETS2)

GT4C-A GTIC 1 ET16

(ETS2)

CPLC18

SW10C-A

GSW2KB 0

SW10C-A

GSW2KB 0

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

For internal use


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

For internal use


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

SMMU supports subscriber 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 750.000 subscribers 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

RS T

J7

J6

W O

RUN

LF

OL

TE

AP

DRAM

S B

CP S I

S CS I

E Tx0

E Rx0

CP

U

E Tx1

E Rx1

AS

7

AP

OPR

ON

OFF

PS

C6-C

B

DBG

RS T

J7

J6

W O

RUN

LF

OL

TE

AP

DRAM

S B

CP S I

S CS I

E Tx0

E Rx0

CP

U

E Tx1

E Rx1

OPR

ON

OFF

PS

C6-C

B

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

MCHU 0

MCHU

1

MCHU

0

FTRB-A 0 FTRB-A 1

OMU

1

OMU

0

PAPU

1

PAPU

0

PAPU

6

PAPU

2

0

PAPU PAPU PAPU

3 4 5

ET16 ET16

(ETS2 (ETS2

1

2

3

4

5

6

7

8

9

10

PAPU

7

PAPU PAPU

PAPU PAPU PAPU PAPU

PAPU PAPU PAPU

8 9

10 11 12 13

14 15 16

PDFU 0 PDFU 0 PDFU 1 PDFU 1

For internal use


SMMU can handle up 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

RS T

J7

J6

W O

RUN

LF

OL

TE

AP

DRAM

S B

CP S I

S CS I

E Tx0

E Rx0

CP

U

E Tx1

E Rx1

AS

7

AP

OPR

ON

OFF

PS

C6-C

B

DBG

RS T

J7

J6

W O

RUN

LF

OL

TE

AP

DRAM

S B

CP S I

S CS I

E Tx0

E Rx0

CP

U

E Tx1

E Rx1

OPR

ON

OFF

PS

C6-C

B

AS

7

AP

For internal use


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

MCHU 0

MCHU

1

MCHU

0

FTRB-A 0 FTRB-A 1

OMU

1

OMU

0

PAPU

1

PAPU

0

PAPU

6

PAPU

2

0

PAPU PAPU PAPU

3 4 5

ET16 ET16

(ETS2 (ETS2

1

2

3

4

5

6

7

8

9

10

PAPU

7

PAPU PAPU

PAPU PAPU PAPU PAPU

PAPU PAPU PAPU

8 9

10 11 12 13

14 15 16

PDFU 0 PDFU 0 PDFU 1 PDFU 1

For internal use



1 2 4 5 6 73

OPR

ON

OFF

PS

C 6

DBG

RS T

J7

J6

W O

RUN

LF

OL

TE

AP

DRAM

S B

CP S I

S CS I

E Tx0

E Rx0

CP

U

E Tx1

E Rx1

IOC

P-E

A

AS

7

AP

AS

7

AP

1 2 4 5 6 7 3

OPR

ON

OFF

- 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 7: CPU Central Processing Unit

PAPU with IOCP-E PAPU with IOCP-EA

For internal use



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

SNDCP

LLC

BSSGPNS cntl

FR

E1Gb/FR (BSS) Gn (GGSN)

PAPU

2G : Gb/FR

Relay

GTP

UDP

IP

Ethernet

SNDCP

LLC

BSSGPNS cntl

UDP/IP

EthernetGb/IP (BSS)

Gn (GGSN)

PAPU

2G : Gb/IP

Relay

GTP

UDP

IP

Ethernet

SNDCP

LLC

BSSGPNS cntl

FR

E1Gb/FR (BSS) Gn (GGSN)

PAPU

2G : Gb/FR

Relay

GTP

UDP

IP

Ethernet

SNDCP

LLC

BSSGPNS cntl

UDP/IP

EthernetGb/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

IP

Ethernet

Ethernet

PAPU CPU

IP

SCTP

M3uA

RANAP

SCCP

Iu control (RAN)

ATM

MTP-3b

ATM relay to IOCP-EA

3G: Iu Control Plane

For internal use



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

connection;

IOCP-E contains 4 Ethernet interfaces: 2 Ethernet connections for the

Gn interface and 2 Ethernet connections for the Iu interface over IP

(optional). IOCP-EA adds 4x155Mbps Fibre ATM interfaces

CPU816-A also contains 4 Ethernet interfaces: 2 Ethernet connections

for the Gb interface over IP and 2 Ethernet connections for EMB

interfaces

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

250.000 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

For internal use


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

For internal use


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

For internal use


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

For internal use


NSN SGSN Introduction – O & M

Logging in SGSN

For internal use



Logging in SGSN

For internal use



Logging in SGSN

For internal use



Understanding SGSN CLI

For internal use



Subscriber Management Commands

Command Description

ZMMO Check subscriber status

ZMMS Check subscriber profile (subscribed APNs)

ZMMN Display Number of subscribers

ZMMD Delete subscriber from SGSN

Command Description

ZFWO Check GB link status

ZEJL Check BVCI status

ZW7I Check Licence installed (used for BVCI Count)

ZQRI Check IP configurations

ZAHO Check system alarms

ZQRX Ping/ Traceroute for any interface

ZWVI Check GT/ MNC/ MCC details for own SGSN

ZWQO Backup

ZGHI Check Charging Gateway Status

Command Description

ZOYI Check SCTP association set status

ZCFI Check IMSI to GT analysis

ZNBI Check GT analysis

ZNAI Check GT Translation results

ZNHI Check Subsystem States

General Health Check and O&M Commands

SS7 Signaling Management Commands

For internal use



Sample Configurations – Gb Link

For internal use



Sample Configurations – PLMN Configuration

For internal use



Sample Configurations – IMSI To GT Table

For internal use



Sample Configurations – LAC Configuration

For internal use



Sample Configurations – Signaling Link status

For internal use



Sample Configurations – Check Unit Load

For internal use



Sample Configurations – Checking System Clock

For internal use


NSN SGSN Introduction – Analysing Traces

For internal use



For internal use



For internal use



For internal use



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

For internal use


Hands On Session

For internal use


Q & A

For internal use


Thank you

137889806-Sgs-n-Training

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