EIGRP Topology Table Issue

[kkalaycioglu]

I've got some EIGRP topology table entries like this:

P X.X.X.X, 0 successors, FD is Inaccessible, serno 71711

via Y.Y.Y.Y (82944/28160), Serial0/0/0

via Z.Z.Z.Z (1869312/732416), Serial5/0/0, serno 81545

via T.T.T.T (3866752/3354752), Serial5/1/0

via U.U.U.U (3866752/3354752), Serial5/1/3

via V.V.V.V (3866752/3354752), Serial5/1/2

via W.W.W.W (3866752/3354752), Serial5/1/1

Despite there's an entry (Y.Y.Y.Y) that should be the successor, it shows no successors and FD is inaccessible. And no route is installed in the ip route table. Any ideas?

Best Regards.

[ruwhite · Accepted solution]

Could you do a show ip eigrp topo and a show ip route for a route in this condition? This is called a 0 successor route, and there's actually a special command (show ip eigrp topo zero) to show them. Generally, this occurs because of a route with a better admin distance in the routing table keeping eigrp from installing the route, but there are other reasons they could occur, including some defects in the code.

Could you also post the version number?

:-)

Russ.W

[kkalaycioglu]

Just the case you mentioned. In first check I missed static routes to these destinations.

Thanks and Best Regards.

[kkalaycioglu]

I've encountered "zero-successor" case in a different lab scenario:

When filtering EIGRP updates using distribute lists:

1. If I apply a global distribute-list:"distribute-list 80 in", intended networks disappear in EIGRP topology table and naturally disappear in the ip route table.

2. If I apply per-interface distribute-list "distribut-list 81 in serial 1" intended networks appear in the topology table but not installed in the ip route table. If This router learns a network for example:3.3.3.0 from only serial1, and filter 3.3.3.0 via per-interface distribute-list, 3.3.3.0 appears in the topology table in "zero-successor" condition. IOS is 12.0(28) Service Provider. Is this situation normal?

Regards.

[ruwhite · Accepted solution]

Yes, this is correct, because this type of distribute list is effectively applied between the EIGRP topo table and the routing table. In some situations a distribute list will give you a zero sucessor route, in others, it will keep the route from being installed in the local topo table.

:-)

Russ.W