Forcing A Change To The Standby Supervisor - Cisco Catalyst 2000 Configuration Handbook

switchover, and the information synchronized to the standby is used when the stand-
by becomes active to minimize the downtime. No link layer or control-plane infor-
mation is synchronized between the active and the standby Supervisors. Interfaces
can bounce after switchover, and the hardware contents need to be reprogrammed.
The RPR+ switchover time is 30 or more seconds. The actual failover time is depend-
ent on the size and complexity of the configuration.
NSF/SSO: Cisco IOS Software supports NSF with SSO. The key differentiators
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apply in where and how these features are applied with the more advanced forms of
these features deployed first in Cisco IOS. SSO expands the RPR+ capabilities to
provide transparent failover of Layer 2 protocols when a supervisor failure occurs.
SSO is stateful for Layer 2 protocols. The PFC and Distributed Forwarding Card
(DFC) hardware tables are maintained across a switchover. This allows for transparent
failover at Layer 2 and Layer 4. NSF works in conjunction with SSO to ensure Layer
3 integrity after a switchover. It allows a router that experiences the failure of an
active Supervisor to continue forwarding data packets along known routes, while the
routing protocol information is recovered and validated. This forwarding can contin-
ue to take place by the leverage of restart mechanisms that allow peering arrange-
ments to recover upon failover. This avoids unnecessary route flaps and network
instability. The failover time is 0 to 3 seconds with NSF/SSO.
SRM/SSO: When the switch is powered on, SRM with SSO runs between the two
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Supervisor engines. The Supervisor engine that boots first becomes the active
Supervisor engine. The MSFC and PFC become fully operational. The configuration
of the redundant Supervisor engine and MSFC is exactly the same as the active
Supervisor engine and MSFC. Processes, such as routing protocols, are created on
both the active MSFC and the redundant MSFC. The redundant Supervisor engine is
fully initialized and configured, which shortens the switchover time. The active
Supervisor engine checks the image version of the redundant Supervisor engine when
the redundant Supervisor engine comes online. If the image on the redundant
Supervisor engine does not match the image on the active Supervisor ENGINE, RPR
mode is used. If the active Supervisor engine or MSFC fails, the redundant
Supervisor engine and MSFC become active. SRM with SSO supports a switchover
time of 0 to 3 seconds for Layer 2 unicast traffic.
Note SRM with SSO is supported only on Supervisor Engine 720 and Supervisor Engine 32.

Forcing a Change to the Standby Supervisor

To reset the active Supervisor engine, enter the following command:
(privileged)reload
Chapter 3: Supervisor Engine Configuration 43