|A route that satisfies a feasibility condition and is kept as a backup route. The condition is that the backup route is loop free.
|The condition that for a route to be considered a backup route, the reported distance received must be less than the feasible distance calculated locally.
|Reported Distance (RD)
|The distance reported by a router to reach a prefix. The reported distance received by a router is the feasible distance observed locally at the remote router.
|Feasible Distance (FD)
|The value for the lowest-metric path to reach the destination prefix.
|The first next-hop router to reach a prefix.
|The route with the lowest metric to reach a destination prefix