As a protection measure against link faults, BGP4+ Auto Fast Reroute (FRR) is applicable to the network topology with primary and backup links. BGP4+ Auto FRR is applicable to services that are very sensitive to packet loss and delays.
As networks evolve continuously, voice, on-line video, and financial services raise increasingly high requirements for real-time performance. Usually, primary and backup links are deployed on a network to ensure the stability of these services. In a traditional forwarding mode, the router selects a route out of several routes that are bound for the same destination network as the optimal route and delivers the route to the FIB table to guide data forwarding. If the optimal route fails, the router has to wait for route convergence to be completed before reselecting an optimal route. During this period, services are interrupted. After the router delivers the reselected optimal route to the FIB table, services are restored. Service interruption in this mode lasts a long time, which cannot meet services' requirements.
After BGP Auto FRR is enabled on a router, the router selects the optimal route from the routes that are bound for the same destination network. In addition, the router automatically adds information about the second optimal route to the backup forwarding entries of the optimal route. If the primary link fails, the router quickly switches traffic to the backup link. The switchover does not depend on route convergence. Therefore, the service interruption time is very short, reaching the sub-second level.
Before configuring BGP4+ Auto FRR, complete the following tasks:
Configure static route or an IGP to ensure that IP routes between routers are reachable.
The system view is displayed.
The BGP view is displayed.
The BGP-IPv6 unicast address family view is displayed.
BGP4+ Auto FRR is enabled for unicast routes.
The configuration is committed.
After the configuration is complete, check whether the configuration has taken effect.
Run the display ipv6 routing-table ipv6-address prefix-length [ longer-match ] [ verbose ] command to check the backup forwarding information of routes in the routing table of a device.