Cisco Cisco ASR 5000
PGW Restart Notification in S4-SGSN
▀ Feature Description
▄ SGSN Administration Guide, StarOS Release 18
Feature Description
The purpose of enabling PGW Restart Notification (PRN) in S4-SGSN is to provide a simple and optimized solution for
handling the signaling overload on the SGSN when a PGW failure occurs. Until release 10, the SGW used to send
Delete Bearer Request for every PDN connection activated through the failed PGW. This results in signaling overload
on the SGSN. From 3GPP Release 10 specifications onwards it is possible for a SGW to indicate a PGW failure through
a single PRN message to the SGSN.
handling the signaling overload on the SGSN when a PGW failure occurs. Until release 10, the SGW used to send
Delete Bearer Request for every PDN connection activated through the failed PGW. This results in signaling overload
on the SGSN. From 3GPP Release 10 specifications onwards it is possible for a SGW to indicate a PGW failure through
a single PRN message to the SGSN.
When the SGW detects that a peer PGW has restarted or it is not reachable, it deletes all the PDN connections
associated with that peer node and releases all the internal resources associated with those PDN connections.
associated with that peer node and releases all the internal resources associated with those PDN connections.
The SGW sends a PGW Restart Notification only to the SGSNs that have configured advertisement of PGW restart
notification in echo request/response messages. When the S4-SGSN receives this message, according to the control
plane IP address of the restarted PGW and the control plane IP address of the SGW on the S4 interface included in the
message, the S4-SGSN deletes all PDN connections associated with the SGW and the restarted PGW. The SGSN also
releases any internal resources associated with those PDN connections.
notification in echo request/response messages. When the S4-SGSN receives this message, according to the control
plane IP address of the restarted PGW and the control plane IP address of the SGW on the S4 interface included in the
message, the S4-SGSN deletes all PDN connections associated with the SGW and the restarted PGW. The SGSN also
releases any internal resources associated with those PDN connections.
The S4-SGSN sends a PGW Restart Notification Acknowledge message in response to the PGW Restart Notification
message sent by the SGW.
message sent by the SGW.