Ihave question on the fourmla, You have mentioned this --> “do we have a feasible successor (backup path)?” we need to learn another formula which is as follwoing:_ your saying Advertised distance of feasible successor < Feasible distance of successor.
Question(1):
what if the value of all Advertised distance of feasible successor is greater than the feasible distance of successor how we can select the backup path??
Question(2):
also what if we need to find the AD and FD to get the Successor and FSuccessor for R2 how we can fill the tables in the image below:
Before fill the table please look at first comment topology and then fill the below table:
Question 1: If the AD of FS is greater than the FD of the successor, then no feasible successor will be selected. That is, if the link fails, there will be no automatic reverting to a feasible successor or backup path. In this case, the DUAL algorithm will be rerun to find the best path to place in the routing table. This condition must be met in order to avoid the possibility of a routing loop.
Question 2: The topology you included has metrics for the specific links that look more like OSPF metrics than EIGRP metrics. However, assuming they are EIGRP metrics, the AD in the table should be populated with the total metric to the destination AS REPORTED by the specific routers. The FD should be the observed metric to the destination from the point of view of R2.
