When successor is down

auos

Hi,

Suppose I have below successor and feasible successor to the network (10.1.1.0/24)

P 10.1.1.0/24, 1 successors, FD is 768
via 10.1.3.1 (768/256), Serial0
via 10.1.5.2 (1536/512), Serial1

Ok, but I could not understand why when successor is down the feasible successor when take place the FD for successors is still without any change, not replace it with FD of feasible successor, (why 768 not be 1536).

P 10.1.1.0/24, 1 successors, FD is 768
via 10.1.5.2 (1536/512), Serial1

BR,
Auos.

iproute

Misunderstood the question. Don't know the answer.

Though I could add: do a clear "ip eigrp neighbors" (with your original successor still being unavailable) and see if the "FD is X" updates. That would at least tell us if it's some sort of hold-over from the old successor.

burbankmarc

It appears that the FD doesn't change when you lose your successor.

I tested it, and my results were the same as yours. When the successor was lost, the FD stayed the same. If I cleared the eigrp neighbors though the new FD was displayed.

When the originial successor was introduced back into the eigrp topology it's FD was displayed.

So it looks as though the FD will only go from lower to higher if the route is reset.

Kris SP

I'm pretty sure the FD and AD don't change, unless someone changed the physical layout. In this case your Successor goes down but the FD and AD of the FS is the same, it just now becomes the Successor. Right?

iproute

Kris SP wrote: »

I'm pretty sure the FD and AD don't change, unless someone changed the physical layout. In this case your Successor goes down but the FD and AD of the FS is the same, it just now becomes the Successor. Right?

That's what I thought was being asked at first also, but the actual question is: "Why when the successor becomes unavailable and the feasible successor becomes the successor, the FD shown for the route is still that of the now dead successor?"

[Before]
P 10.1.1.0/24, 1 successors, FD is 768
via 10.1.3.1 (768/256), Serial0
via 10.1.5.2 (1536/512), Serial1

[After]
P 10.1.1.0/24, 1 successors, FD is 768
via 10.1.5.2 (1536/512), Serial1

kryolla

it could be that if the FD was to change that means DUAL performed the recomputation and then it would need to be flooded in update packets which might be uneccesary but Im too lazy to find a tech doc to support this.

networker050184

kryolla wrote: »

it could be that if the FD was to change that means DUAL performed the recomputation and then it would need to be flooded in update packets which might be uneccesary but Im too lazy to find a tech doc to support this.

That would be my guess as well. If the FD were to change then the route would need to be recalculated.