When the switch is powered on, SRM with SSO runs between the two Supervisor
Engines. The Supervisor Engine that boots first becomes the active Supervisor.
The Multilayer Switch Feature Card 3 MSFC3 and Policy Feature Card 3 PFC3
become fully operational.
If the active Supervisor Engine 720 or MSFC3
fails, the redundant Supervisor Engine 720 and MSFC3 become active. The newly
active Supervisor Engine 720 uses the existing PFC3 Layer 3 switching
information to forward traffic while the newly active MSFC3 builds its routing
table.
The routing protocols have to establish connectivity with their neighbor or
peers and the Routing Information Base is built. During this time packet
forwarding cannot take place.