EIGRP Terminology

Question 1

Successor route

Answer 1

The route with the lowest path metric to reach a destination.

The successor route for R1 to reach 10.4.4.0/24 on R4 is R1 → R3 → R4

Question 2

Successor

Answer 2

The first next-hop router for the successor route.

The successor for 10.4.4.0 /24 is R3.

Question 3

Feasible Distance (FD)

Answer 3

The metric value for the lowest-metric path to reach a destination.

The feasible distance is calculated locally.

The FD calculated by R1 for the 10.4.4.0/24 network is 3328 (that is, 256+256+2816).

Question 4

Reported Distance

Answer 4

The distance reported by a router to reach a prefix.

The reported distance value is the feasible distance for the advertising router.

R3 advertises the 10.4.4.0/24 prefix with an RD of 3072.

R4 advertises the 10.4.4.0/24 to R1 and R2 with an RD of 2816.

Question 5

Feasibility condition

Answer 5

A condition under which, for a route to be considered a backup route, the reported distance received for that route must be less than the feasible distance calculated locally. This logic guarantees a loop-free path.

Question 6

Feasible Successor

Answer 6

A route that satisfies the feasibility condition and is maintained as a backup route. The feasibility condition ensures that the backup route is loop free.

The route R1 → R4 is the feasible successor because the RD 2816 is lower than the FD 3328 for the R1 → R3 → R4 path.