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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter6 Configuring Supervisor Engine Redundancy Using RPR and SSO
Understanding Supervisor Engine Redundancy
When power is first applied to a switch, the supervisor engine that boots first becomes the active
supervisor engine and remains active until a switchover occurs.
A switchover will occur when one or more of the following events take place:
•The active supervisor engine fails (due to either hardware or software function) or is removed.
•A user forces a switchover.
•A user reloads the active supervisor engine.
Table 6 -2 provides information about chassis and supervisor engine suppor t for redundancy.
RPR Operation
RPR is supported in Release 12.2(12c)EW and later releases. When a redundant supervisor engine runs
in RPR mode, it starts up in a partially-initialized state and is synchronized with the persistent
configuration of the active supervisor engine.
Note Persistent configuration includes the following components: startup-config, boot variables,
config-register, and VLAN database.
The redundant supervisor engine pauses the startup sequence after basic system initialization, and in the
event that the active supervisor engine fails, the redundant supervisor engine will become the new active
supervisor engine.
In a supervisor engine switchover, traffic is disrupted because in the RPR mode all of the physical ports
restart since there is no state maintained between supervisor engines relating to module types and
statuses. When the redundant supervisor engine completes its initialization, it will read hardware
information directly from the module.
SSO Operation
SSO is supported in Release 12.2(20)EWA and later releases. When a redundant supervisor engine runs
in SSO mode, the redundant supervisor engine starts up in a fully-initialized state and synchroni zes with
the persistent configuration and the running configuration of th e active supervisor engine. It
subsequently maintains the state on the protocols listed below, and all changes in hardware and software
states for features that support stateful switchover are kept in sync. Consequently, it offers no zero
interruption to Layer 2 sessions in a redundant supervisor engine configuration.
Table6-2 Chassis and Supervisor Support
Chassis
(Product Number) Supported Supervisor Engines
Catalyst 4507R
(WS-C4507R)
Supports redundant Supervisor Engine II-Plus (WS-X4013+),
Supervisor Engine IV (WS-X4515), redundant Supervisor
Engine V (WS-X4516)
Catalyst 4510R
(WS-C4510R)
Supports redundant Supervisor Engine V (WS-X4516)