The Catalyst 6500 Distributed Forwarding Card-3 is installed in DFC-enabled line-card modules that perform distributed forwarding supported by the Catalyst 6500 Supervisor Engine 720 as a field upgrade. These line cards include the WS-X6516-GBIC and the WS-X6816-GBIC.
When the Distributed Forwarding Card-3 is installed, modules that are DFC-enabled make forwarding decisions locally, leaving the supervisor engine free to perform routing and management functions.
The Distributed Forwarding Card-3 replicates Layer 2 and 3 forwarding logic of the Supervisor 720's PFC-3 on each DFC-3 equipped linecard. This enables hardware acceleration of IPv6, MPLS, GRE, QoS, ACL policy enforcement and more. The DFC-3 equipped interface modules are backward compatible with all other Catalyst 6500 interface modules. However, they must be used with a Supervisor 720 and any other modules that will use distributed forwarding must also be DFC-3 equipped.