Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
▀ Features and Functionality
▄ SGSN Administration Guide, StarOS Release 18
Flex Pooling (Iu / Gb over S16) Support on the S4-SGSN
This feature adds the SGSN Pooling functionality across S16 (peer S4-SGSN) interface, so that the default SGSN can
forward the received Context Requests from the non-Pooled SGSN to the right pooled SGSN, based on the NRI in P-
TMSI. Flex pooling provides better scalability and load balancing. A new CLI command for pooling has been provided
under eGTP Service Configuration to enable S4-SGSN pooling across the S16 interface. For more information on the
command, refer to the Command Line Interface Reference Manual.
forward the received Context Requests from the non-Pooled SGSN to the right pooled SGSN, based on the NRI in P-
TMSI. Flex pooling provides better scalability and load balancing. A new CLI command for pooling has been provided
under eGTP Service Configuration to enable S4-SGSN pooling across the S16 interface. For more information on the
command, refer to the Command Line Interface Reference Manual.
This feature requires the SGSN S3/S4 license and Flex feature license - no additional feature licenses are required.
LORC Subscriber Overcharging Protection on S4-SGSN
With Release 17.0, the S4-SGSN now supports Subscriber Overcharging Protection to prevent both 2G and 3G
subscribers from being overcharged when a loss of radio coverage (LORC) occurs over the S4 interface.
subscribers from being overcharged when a loss of radio coverage (LORC) occurs over the S4 interface.
As a part of this functionality, the operator must configure all cause codes on the SGSN. If the SGSN receives a cause
code via Iu/Gb interfaces that matches one of the cause codes configured on the SGSN, then the SGSN includes the
ARRL (Abnormal Release of Radio Link) bit in the Release Access Bearer Request.
code via Iu/Gb interfaces that matches one of the cause codes configured on the SGSN, then the SGSN includes the
ARRL (Abnormal Release of Radio Link) bit in the Release Access Bearer Request.
This feature ensures more accurate billing by protecting the subscriber from overcharging in instances where abnormal
radio resource release occurs. For more information about this feature, refer to the feature chapter LORC Subscriber
Overcharging Protection on S4-SGSN in this Guide.
radio resource release occurs. For more information about this feature, refer to the feature chapter LORC Subscriber
Overcharging Protection on S4-SGSN in this Guide.
Summary of Functional Differences between an S4-SGSN and an SGSN (Gn/Gp)
Since the S4-SGSN is configured with 2G, 3G, and/or dual access SGSN services before being configured with
enhancements to enable communication with the EPC network, it shares similarities with a Gn/Gp SGSN. But, the S4-
SGSN also contains a number of functional differences. The following table summarizes these differences.
enhancements to enable communication with the EPC network, it shares similarities with a Gn/Gp SGSN. But, the S4-
SGSN also contains a number of functional differences. The following table summarizes these differences.
Table 1. Summary of Functional Differences between SGSN and S4-SGSN
Procedure
Gn/Gp SGSN
S4-SGSN