Cisco Cisco Packet Data Interworking Function (PDIF)
Interchassis Session Recovery
▀ Overview
▄ ASR 5500 System Administration Guide, StarOS Release 17
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Overview
The ICSR feature provides the highest possible availability for continuous call processing without interrupting
subscriber services. ICSR allows the operator to configure geographically distant gateways for redundancy purposes. In
the event of a node or gateway failure, ICSR allows sessions to be transparently routed around the failure, thus
maintaining the user experience. ICSR also preserves session information and state.
subscriber services. ICSR allows the operator to configure geographically distant gateways for redundancy purposes. In
the event of a node or gateway failure, ICSR allows sessions to be transparently routed around the failure, thus
maintaining the user experience. ICSR also preserves session information and state.
ICSR is implemented through the use of redundant chassis. The chassis are configured as primary and backup, with one
being active and one standby. Both chassis are connected to the same AAA server. A checkpoint duration timer controls
when subscriber data is sent from the active chassis to the standby chassis. If the active chassis handling the call traffic
goes out of service, the standby chassis transitions to the active state and continues processing the call traffic without
interrupting the subscriber session.
being active and one standby. Both chassis are connected to the same AAA server. A checkpoint duration timer controls
when subscriber data is sent from the active chassis to the standby chassis. If the active chassis handling the call traffic
goes out of service, the standby chassis transitions to the active state and continues processing the call traffic without
interrupting the subscriber session.
The chassis determine which is active through a proprietary TCP-based connection known as the Service Redundancy
Protocol (SRP) link. The SRP link is used to exchange Hello messages between the primary and backup chassis and
must be maintained for proper system operation.
Protocol (SRP) link. The SRP link is used to exchange Hello messages between the primary and backup chassis and
must be maintained for proper system operation.
ICSR licenses are currently supported for the following services:
eHRPD – Evolved High Rate Packet Data
ePDG – Evolved Packet Data Gateway
GGSN – Gateway GPRS Support Node
HA – Home Agent
IPSG – IP Services Gateway
MME – Mobility Management Entity
P-GW – Packet Data Network Gateway
PDSN – Packet Data Serving Node
S-GW – Serving Gateway
SAEGW – System Architecture Evolution Gateway
L2TP Access Concentrator (LAC) functionality for ICSR is supported by the following services:
eGTP – enhanced GPRS Tunneling Protocol
GGSN – Gateway GPRS Support Node
SAEGW – System Architecture Evolution Gateway
L2TP Access Concentrator (LAC) functionality for ICSR is not supported by the following services:
HA – Home Agent
PMIP - P-GW – Proxy Mobile IP - Packet Data Network Gateway
L2TP Network Server (LNS) functionality for ICSR is not supported by any services.
Important:
For releases prior to 17.0, ICSR should not be configured on chassis supporting L2TP calls.