The Catalyst 4500 and 6500 switches support fault resistance by allowing a
redundant supervisor engine to take over if the primary supervisor engine
fails. Cisco NSF works with SSO to minimize the amount of time the routing
protocols require to rebuild their tables following a switchover. Catalyst 4500
and 6500 series switches also support route processor redundancy (RPR), route
processor redundancy plus (RPR+), and single router mode with stateful
switchover (SRM with SSO) for redundancy.
The following events cause a
switchover:
- A hardware failure on the active supervisor engine
- Clock synchronization failure between supervisor engines
- A manual switchover