Engineering Rules

 

This section provides SGSN-specific engineering rules or limit guidelines for releases 8.0, 8.1, and 9.0. These limits should be considered prior to configuring an SGSN for network deployment. The limits documented in this section are hardcoded into the SGSN system and are not configurable, however, they can, and often do, vary for 2G versus 3G systems.

Generic platform and system rules or limits can be found in the “Engineering Rules” appendix in the System Administration Guide.

Service Rules

The following engineering rules define the limits for the various services configured on the SGSN (system):

Service Rules for the SGSN

Features	Limits	Comments
Maximum number of (all) services (regardless of type) configurable per SGSN (system).	256	This limit includes the number of SGTP services, IuPS Services, and MAP Services.
Max. number of MAP services supported by a single GPRS (2G) or SGSN (3G) service.	1	Although the limit is 1 MAP Service configured per GPRS Service or SGSN Service, the GPRS or SGSN service can access multiple MAP Services using SGSN Operator Policies.
Max. number of SGTP services supported by a single GPRS or SGSN service.	1	Although the limit is 1 SGTP Service configured per GPRS Service or SGSN Service, the GPRS or SGSN service can access multiple SGTP Services using SGSN Operator Policies.
Max. number of Gs services supported by a single GPRS or SGSN service.	1	Although the limit is 1 Gs Service configured per GPRS Service or SGSN Service, the GPRS or SGSN service can access multiple Gs Services using SGSN Operator Policies.
Max. number of SCCP network configurations supported by a single MAP service.	1
Max. number of Gs services supported on an SGSN (system)	32
Maximum number of LACs per Gs service	32

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SGSN Connection Rules

The following limitations apply to both 2G and 3G SGSNs.

Features	Limits	Comments
Maximum number of entry authentication triplets (RAND, SRES, and KC) and quintuplets stored per MM context	5
Maximum number of logically connected SMSCs	no limit	Limit would be based on the number of routes if directly connected. No limit if GT is used.
Maximum number of logically connected HLRs	no limit	Limit would be based on the number of routes if directly connected. No limit if GT is used.
Maximum number of logically connected EIRs	1	SGSN will be connected to only 1 EIR.
Maximum number of connected MSCs	see comment	System supports a max of 32 LACs per Gs service and a max of 32 Gs service.
Maximum number of concurrent PDP contexts per active user	11
Maximum number of logically connected GGSNs per Gn/Gp interface	no limit
Maximum number of packets buffered while other engagement Maximum number of packets buffered in suspended state Maximum number of packets buffered during RAU	see comment	- Minimum of 2KB/subscriber.- Maximum of 10KB/subscriber -- if buffers are available in the shared pool*. (*SGSN provides a buffer pool of 10M per session manager - buffers to be shared by all subscribers “belonging” to that session manager.)

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SGSN Operator Policy Rules

 

The following engineering rules apply for the entire system when the system is configured as an SGSN. As APN policies are configured per policy, the APN policy rules are included in the following table:

Operator Policies

Operator Policy Rules for the SGSN

Features	Limits	Comments
Maximum number of operator policies per SGSN	1000	Includes the 1 default policy.
Maximum number of IMSI ranges configurable per operator policy	1
Maximum number of Equivalent PLMNs for 2G and 3G per operator policy	15	IMSI range must be configured in the operator policy.
Maximum number of Equivalent PLMNs for 2G per operator policy	15
Maximum number of Equivalent PLMNs for 3G per operator policy	15
Maximum number of static SGSN addresses per operator policy	256
Maximum number of Location Area Code lists per operator policy	5
Maximum number of LACs per Location Area Code list	100
Maximum number of Allowed Zone Code lists per operator policy	10
Maximum number of LACs per Allowed Zone Code list	10
Maximum number of Integrity Algorithms for 3G per operator policy	2
Maximum number of Encryption Algorithms for 3G per operator policy	3
Maximum number APN policies per operator policy	1000
Maximum number of Gateway Addresses per APN policy	16	APN policies are associated with a specific operator policy.

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SS7 Rules

SS7 Routing

SS7 Routing Rules for SGSN

Features	Limits	Comments
Maximum number of SS7 routing domains supported by an SGSN	12
Maximum number of SS7 routes supported by an SGSN	2048	This includes the self point code of the peer, 1 per link-set and 1 per peer-server
Maximum number of routes possible via a link-set	2048	This includes the self point code of the peer, 1 per link-set and 1 per peer-server
Maximum number of routes possible via peer-server	2048	This includes the self point code of the peer, 1 per link-set and 1 per peer-server
Maximum number of different levels of priority for link sets used in a single route set	16

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SIGTRAN

SIGTRAN Rules for SGSN

Features	Limits	Comments
Maximum number of peer servers	256
Maximum number of peer servers per SS7RD	144
Maximum number of PSPs per peer server	4
Maximum number of ASPs per SS7RD	4
Maximum number of SCTP endpoints per ASP	2
Maximum number of of SCTP endpoints per PSP	2
Maximum number of SCTP endpoints per PSP (dynamically learnt)	5

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Broadband SS7

Broadband SS7 Rules for SGSN

Features	Limits	Comments
Maximum number of MTP3 linksets	256
Maximum number of MTP3 linksets per SS7RD	144
Maximum number of MTP3 links per linkset	16
Maximum number of MTP3 links per combined linkset	16

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SCCP

SCCP Rules for SGSN

Features	Limits	Comments
Maximum number of SCCP networks	12
Maximum number of destination point codes (DPCs)	2048
Maximum number of SSNs per DPC	3

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GTT

GTT Rules for SGSN

Features	Limits	Comments
Maximum number of associated GTTs	16
Maximum number of actions per association	8
Maximum number of address maps	4096
Maximum number of out-addresses per address map	5

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SGSN Interface Rules

The following information relates to the virtual interfaces supported by the SGSN:

System-Level

System Rules on the SGSN

Features	Limits	Comments
Maximum supported size for IP packets (data)	1480
Maximum recovery/reload time	17 mins.

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3G Interface Limits

3G Interface Rules for SGSN

Features	Limits	Comments
Maximum number of RNCs	128
Maximum number of RNCs controlling the same RA	no limit
Maximum number of LACs per RNC	50
Maximum number of RACs per LAC in one RNC	50
Maximum number of GTPU addresses per SGTP service	12
Maximum number of ATM VPIs and VCIs per Iu interface	512

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2G Interface Limits

2G Interface Rules - Gb over Frame Relay

Features	Limits	Comments
Maximum number of LACs per SGSN	128
Maximum number of NSEs	512
Maximum number of LACs per NSE	50
Maximum number of RACs per LAC	50
Maximum number of NSEs controlling the same RA	128
Maximum number of NSVCs per NSE	128
Maximum number of BVCs per NSE	1024
Maximum number of cell sites supported	64,000

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2G Interface Rules - Gb over IP

Features	Limits	Comments
Maximum number of NSEs	256
Maximum number of Local NSVLs per SGSN	4	Gb over IP interface
Maximum number of Peer NSVLs per NSE	64
Maximum number of LACs per SGSN	128	Gb over IP interface
Maximum number of LACs per NSE	50
Maximum number of RACs per LAC	50
Maximum number of NSEs controlling the same RA	64
Maximum number of NSVCs per NSE	256
Maximum number of BVCs per NSE	1024
Maximum number of cell sites supported	64,000
Maximum number of 802.1q VLANs per Gb interface	1024

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