Implementing Hardware and Software Redundancy on Modular Switches
Cisco Catalyst 6500 switch

The Catalyst 6500 platform provides Layer 3 functionality through a Multilayer Switch Function card (MSFC) residing on the Supervisor Engine module. As of this writing, the current iteration is the MSFC3 which is an integral part of the Supervisor Engine 720. The MSFC3 adds high performance, multilayer switching, and routing intelligence to the Catalyst. Equipped with a high-performance processor, the MSFC3 runs Layer 2 protocols on one CPU and Layer 3 protocols on the second CPU. These protocols include VLAN Trunking Protocol, routing protocols, multimedia services, security services; nearly any protocol capable of running on the high end Cisco routing platforms.

The MSFC builds the Cisco Express Forwarding Information Base table in software and downloads this table to the hardware or ASIC on the Policy Feature Card (PFC) and any installed Distributed Forwarding Card (DFC).

An MSFC3 with PFC3 on a Supervisor 720 adds Stateless Switchover (SSO) and Non Stop Forwarding (NSF) to the arsenal of Catalyst fault tolerance features.