Cisco Catalyst Switches like Catalyst 6500 series and Catalyst 4500-R series and highend routers lsupport Redundant Supervisor modules to be installed. The Redudndant Supervisor Modules startup and run as a standby device and takes over when the active module fails. The Active Supervisor Engine syncs time and config onto the redundant supervisor engine every 1 sec and when running-config is copied to the Start-up config. The failover mode Stateful switchOver (SSO) we use here allows failover in 1 second or more.
Check your Catalyst switch / Routers and the Supervisor Engine documentation for the supported modes of redundancy.
Enable Supervisor Engine Redundancy
From the Global Configuration mode, enable redundancy for the Supervisor engine.
ciscorouter# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.ciscorouter(config)# redundancy
ciscorouter(config-red)# mode sso
ciscorouter(config-red)# main-cpu
ciscorouter(config-red)# end
This will cause standby supervisor module to restart and it begins to work in Stateful SwitchOver standby mode.
Display Redundancy mode
To display the operating Redundancy mode use the following command:
ciscorouter# show redundancy states