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New Member

EIGRP Topology serno

I have a network running eigrp (ios 11.2).

We have redistributed connected to redistribute a route.

we have noticed that a router is preferring a worse cost route. It looks like it prefers this route because of a serno entry.

P, 1 successors, FD is 80035840

via (80035840/80030720), Hssi1/0.1, serno 233960

via (284160/28160), Ethernet0/0

via (284160/28160), Ethernet0/1

What does this serno mean?

Consequently why is the router preferring this route?

How can I get the router to accept the correct route?


Re: EIGRP Topology serno

When you redistribute the route becomes external , with an AD of 170. an AD of 90 is going to be preferred over 170 , Can you paste in a sh ip route and a sh ip eigrp top

New Member

Re: EIGRP Topology serno

Many thanks you have answered why the route is preferred. What does the serno mean?


Re: EIGRP Topology serno

not sure I think it means serial number could be a pointer to a database entry.

New Member

Re: EIGRP Topology serno

Thanks. It would just be interesting to know for future ref.

Many thanks for your quick replies.



Re: EIGRP Topology serno

The serial number is used for the reliable transmission of the topology table information using multicast. Essentially, when a multicast packet is built, the router records the serial numbers of the routes that are put in the packet. When the packet is acknowledged, the router knows it can move to the route in the topo table with the next higher serial number of the one that was just acknowledged.