Cisco Cisco Packet Data Gateway (PDG)
Interchassis Session Recovery
Overview ▀
ASR 5000 System Administration Guide, StarOS Release 18 ▄
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Important:
ICSR support for LAC requires a separate LAC license, as well as an Inter-Chassis Session Recovery
license.
Important:
Contact your Cisco account representative to verify whether a specific service supports ICSR as an
option.
Interchassis Communication
Chassis configured to support ICSR communicate using periodic Hello messages. These messages are sent by each
chassis to notify the peer of its current state. The Hello message contains information about the chassis such as its
configuration and priority. A dead interval is used to set a time limit for a Hello message to be received from the
chassis’ peer. If the standby chassis does not receive an Hello message from the active chassis within the dead interval,
the standby chassis transitions to the active state. In situations where the SRP link goes out of service, a priority scheme
is used to determine which chassis processes the session. The following priority scheme is used:
chassis to notify the peer of its current state. The Hello message contains information about the chassis such as its
configuration and priority. A dead interval is used to set a time limit for a Hello message to be received from the
chassis’ peer. If the standby chassis does not receive an Hello message from the active chassis within the dead interval,
the standby chassis transitions to the active state. In situations where the SRP link goes out of service, a priority scheme
is used to determine which chassis processes the session. The following priority scheme is used:
route modifier
chassis priority
SPIO MAC address
Checkpoint Messages
Checkpoint messages are sent from the active chassis to the standby chassis. These messages are sent at specific
intervals and contain all the information needed to recreate the sessions on the standby chassis, if that chassis were to
become active. Once a session exceeds the checkpoint duration, checkpoint data is collected on the session.
intervals and contain all the information needed to recreate the sessions on the standby chassis, if that chassis were to
become active. Once a session exceeds the checkpoint duration, checkpoint data is collected on the session.
SRP CLI Commands
Exec Mode CLI Commands
Exec mode srp CLI configuration commands can be used to enable, disable and initiate SRP functions. The table below
lists and briefly describes these commands. For complete information see the Exec Mode Commands (D-S) chapter of
the Command Line Interface Reference.
lists and briefly describes these commands. For complete information see the Exec Mode Commands (D-S) chapter of
the Command Line Interface Reference.