Reducing Sync-Up Time With Standby Icsr Chassis; Verifying Srp Configuration - Cisco ASR 5500 Administration Manual

Interchassis Session Recovery
The compression keyword will only appear if a special ICSR optimization feature license has been
Important
purchased and installed. Contact your Cisco account representative for assistance.
The following command sequence enables the use of LZ4 compression:
configure
context context_name
service-redundancy-protocol
checkpoint session compression lz4
end
LZ4 compression is effective only if both chassis are configured with LZ4. If any one chassis has zlib (default)
configured, the compression algorithm reverts to zlib. The algorithm is negotiated only during initial socket
establishment. Once agreed no more negotiation takes place until the TCP socket connection is reset.

Reducing Sync-Up Time with Standby ICSR Chassis

The default method for synchronizing the SRP database requires tens of seconds of delay whenever the TCP
connection between the Active and Standby session managers is established. Once the TCP connection is
established, heart beat messages are exchanged between both ICSR chassis every 3 seconds. The standby
chassis waits for seven heart beat messages from the active chassis before it is ready to accept data. This may
cause significant delay in session manager database synchronization on the standby chassis.
You can enable an aggressive method for synchronizing the session manager database reduces recovery time
in the following scenarios:
• Standby Session Manager crash
• Packet processing card failure on Standby chassis
• Standby chassis reboot
• Temporary loss and recovery of SRP connection
The aggressive method reduces the number of heartbeat messages and amount of housekeeping information
exchanged between ICSR chassis.
The SRP Configuration mode standby database-recovery aggressive command allows you to select normal
or aggressive restoration of the SRP database.
The following command sequence enables the aggressive recovery mode:
configure
context context_name
service-redundancy-protocol
standby database-recovery aggressive
end
The default form of this command restores the normal mode of SRP database recovery.

Verifying SRP Configuration

Verify that your SRP contexts were created and configured properly by running the show srp info command
(Exec Mode) on each chassis.
Notes:
Configuring the Service Redundancy Protocol (SRP) Context
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