Configuring Interchassis Session Recovery (Icsr) - Cisco ASR 5000 Administration Manual

Interchassis Session Recovery
a switchover. During the switchover, the standby chassis begins advertising its srp-activated loopback and
pool routes into the routing domain. Once the chassis becomes active, it continues to process existing AAA
services and subscriber sessions that had checkpoint information, and is also able to establish new subscriber
sessions.
When the primary chassis is back in service, it sends Hello messages to the configured peer. The peer sends
a response, establishes communication between the chassis, and sends Hello messages that contain configuration
information. The primary chassis receives an Hello message that shows the backup chassis state as active and
then transitions to standby. The Hello messages continue to be sent to each peer, and checkpoint information
is now sent from the active chassis to the standby chassis at regular intervals.
When chassis switchover occurs, the session timers are recovered. The access gateway session recovery is
recreated with the full lifetime to avoid potential loss of the session and the possibility that a renewal update
was lost in the transitional checkpoint update process.

Configuring Interchassis Session Recovery (ICSR)

Important
This section describes how to configure basic ICSR on each chassis. For information on commands that
configure additional parameters and options, refer to the Command Line Interface Reference.
Important
The procedures described below assume the following:
• The chassis have been installed and configured with core network services.
• In addition, the IP address pools must be srp activated.
• AAA server is installed, configured and accessible by both chassis.
• BGP router installed and configured. See Routing for more information on configuring BGP services.
The ICSR configuration must be the same on the primary and backup chassis. If each chassis has a different
Service Redundancy Protocol (SRP) configuration, the session recovery feature does not function and
sessions cannot be recovered when the active chassis goes out of service.
For releases prior to StarOS 17.0, ICSR should not be configured for chassis supporting L2TP calls.
For more configuration information and instructions on configuring services, refer to the respective
product Administration Guide.
For more information on configuring the AAA server, refer to the AAA Interface Administration and
Reference.
Configuring Interchassis Session Recovery (ICSR)
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