BGP Fast Re-Route (FRR) Feature Overview
BGP fast reroute is a feature that brings together indirection techniques in the forwarding plane and pre-computation of BGP backup paths in the control plane to support fast reroute of BGP traffic around unreachable/failed BGP next-hops.
The backup/alternate path provides a fast reroute mechanism to counter a singular network failure.
Cisco use case:
- BGP Fast Reroute (FRR) provides a best path and a backup/alternate path in BGP, RIB, and Cisco Express Forwarding. BGP FRR provides a very fast reroute mechanism into the RIB and Cisco Express Forwarding on the backup BGP next hop to reach a destination when the current best path is not available.
- BGP FRR precomputes a second best path in BGP and gives it to the RIB and Cisco Express Forwarding as a backup/alternate path, and Cisco Express Forwarding programs it into line cards.
- Therefore, BGP FRR sets up the best path and backup/alternate path. The BGP PIC feature provides the ability for Cisco Express Forwarding to quickly switch the traffic to the other egress ports if the current next hop or the link to this next hop goes down.
Reference:
Nokia
