Usage Scenario
If master and backup PEs are deployed, routes are selected based on BGP route selection rules; if the primary link fails, the BGP route convergence takes a long time because no backup route is available. To address this problem, run the bestroute best-external command to enable a BGP device to select Best External routes if the route preferentially selected based on BGP route selection rules is an IBGP route.
Precautions
The bestroute best-external command only enables a BGP device to select Best External routes. To enable the BGP Best External function, you also need to run the peer advertise best-external command to enable the BGP device to advertise Best External routes to its peers.