# Engineering Rules

This section provides SGSN-specific 2.5G, 3G , and common engineering rules or limit guidelines for the current release. These limits are hardcoded into the SGSN system and are not configurable. The limits are documented here because they should be considered prior to configuring an SGSN for network deployment.

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):
Table 1. 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 GPRS services, SGSN services, SGTP services, IuPS Services, and MAP Services.
Max. number of eGTP services supported by a GPRS/SGSN service. | 1 | When configured for S4-SGSN. The same eGTP service should be associated with both the GPRS and the SGSN service.
Max. number of HSS peer services supported by a single GPRS or SGSN service. | 1 | When configured for S4-SGSN.
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 Operator Policies.
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 Operator Policies.
Max. number of Gs services supported on an SGSN (system) | 12 |
Maximum number of LACs per Gs service | 128 |
Max. number of MAP Service configurations supported by a single SCCP network. | 1 |
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 Operator Policies.

Note:

Maintaining a large number of services increases the complexity of management and may impact overall system performance. Therefore, it is recommended that a large number of services only be configured if your application absolutely requires it. Please contact your service representative for optimization suggetions and more information on service limits.

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 | 5 (unused) + 5 (used) Triplets/Quituplets
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 logically connected MSCs | see comment | System supports a max of 128 LACs per Gs service and a max of 12 Gs service.
Maximum number of concurrent PDP contexts per active user | 11 |
Maximum number of logically connected GGSNs per Gn/Gp interface | 20000 |
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 common buffer pool for 2G and 3G subscribers of 10M per session manager; buffers to be shared by all subscribers “belonging” to that session manager.) - Additional 2G subscriber buffer pool in BSSGP.

Operator Policy Rules

The following engineering rules apply for the entire system when the system is configured as an SGSN.

The limits listed in the table below are applicable for an ASR 5000 running a standalone SGSN application on a PSC2/PSC3. Limits may be lower when using a PSC1 or in combo nodes, such as SGSN+GGSN.

Features | Limits | Comments
--- | --- | ---
Maximum number of Operator Policies | 1000 | Includes the 1 default policy.
Maximum number of Call-Control Profiles | 1000 | .
Maximum number of APN Profiles | 1000 | .
Maximum number of IMEI Profiles | 1000 | .
Maximum number of APN Remap Tables | 1000 | .
Maximum number of APN remap entries per APN Remap Table | 100 | .
Maximum number of IMSI ranges under SGSN mode | 1000 | .
Maximum number of IMEI ranges per operator policy | 128 | .
Maximum number of APN profile associations per operator policy | 128 | .
Maximum number of call-control profiles per opreator policy | 1 | .
Maximum number of APN remap tables per operator policy | 1 | .
Call-Control Profiles | . | .
Maximum number of equivalent PLMN for 2G and 3G | 15 | Mandatory to configure the IMSI range. Limit per call-control profile.
Maximum number of equivalent PLMN for 2G | 15 | Limit per call-control profile.
Maximum number of equivalent PLMN for 3G | 15 | Limit per call-control profile.
Maximum number of static SGSN addresses | 256 | Limit per PLMN.
Maximum number of location area code lists | 5 | .
Maximum number of LACs per location area code list | 100 | .
Maximum number of allowed zone code lists | 10 | .
Maximum number of allowed zone code lists | no limit | For Release 12.2
Maximum number of LACs per allowed zone code list | 100 | .
Maximum number of integrity algorithms for 3G | 2 | .
Maximum number of encryption algorithms for 3G | 3 | .
APN Profiles | . | .
Maximum number of APN profiles | 1000 | .
Maximum number of gateway addresses per APN profile | 16 | .

SS7 Rules

SS7 Routing

Table 2. 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 |

SIGTRAN

Table 3. SIGTRAN Rules for SGSN

Features | Limits | Comments
--- | --- | ---
Maximum number of peer servers | 144 |
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 |

Broadband SS7

Table 4. 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 |

SCCP

Table 5. 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 |

GTT

Table 6. GTT Rules for SGSN

Features | Limits | Comments
--- | --- | ---
Maximum number of associated GTTs | 16 |
Maximum number of actions per association | 8 | .
Maximum number of actions per association | 15 | For Release 12.2
Maximum number of address maps | 4096 |
Maximum number of out-addresses per address map | 5 |

SGSN Interface Rules

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

System-Level

Table 7. System Rules on the SGSN

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

3G Interface Limits

Table 8. 3G Interface Rules for SGSN

Features | Limits | Comments
--- | --- | ---
Maximum number of RNCs | See comment | Supports upto 144 directly connected RNC and 1024 indirectly connected through gateways.
Maximum number of RNCs controlling the same RA | no limit |
Maximum number of RAIs per RNC | 2500 | .
Maximum number of RAIs per SGSN | 2.5K | 2.5k is the recommended max RAI per SGSN, however, there is no hard limit imposed. Adding more RAIs may lead to memory issues
Maximum number of GTPU addresses per SGTP service | 12 |

2G Interface Limits

Table 9. 2G Interface Rules - Gb over Frame Relay

Features | Limits | Comments
--- | --- | ---
Maximum number of NSEs | 2048 | Limit is total of FR + IP
Maximum number of RAIs per SGSN | 2.5K | 2.5k is the recommended max RAI per SGSN, however, there is no hard limit imposed. Adding more RAIs may lead to memory issues
Maximum number of NSEs controlling the same RA | no limit |
Maximum number of NSVCs per NSE | 128 |
Maximum number of BVCs per NSE | max / SGSN is 64000 |
Maximum number of cell sites supported | 64,000 |

Table 10. 2G Interface Rules - Gb over IP

Features | Limits | Comments
--- | --- | ---
Maximum number of NSEs | 2048 | Limit is total of FR + IP
Maximum number of Local NSVLs per SGSN | 4 |
Maximum number of Peer NSVLs per NSE | 128 |
Maximum number of NSE controlling the same RA | no limit |
Maximum number of NSVCs per NSE | 512 |
Maximum number of BVCs per NSE | max / SGSN is 64000 |
Maximum number of cell sites supported | 64000 |
Maximum number of 802.1q VLANs per Gb interface | 1024 |
Maximum number of RAIs per SGSN | 2.5K | 2.5k is the recommended max RAI per SGSN, however, there is no hard limit imposed. Adding more RAIs may lead to memory issues