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EIGRP Router Incorrectly advertising route

A new network 172.16.20.0/24 was added on a router in the US. After having some problems getting to other devices on the 172.16.1.0/24 network, the new network was removed. Many routers in the UK still contain this route. Clearing the route on each router doesn't help as they continue to learn it from a neighboring router. We have not able to clear the route on these routers. A traceroute lfrom the US leads to 2 routers and loops between them. Each one says it learned the route from the other one. The only way I could fix it was to block the advertisement with a distribute-list. Any ideas why it wouldn't clear when the route was removed and cleared on the originating router ?

7 REPLIES
Silver

Re: EIGRP Router Incorrectly advertising route

A couple of questions:

1. What code are you running on the routers that are hanging onto this route?

2. Can you paste one of the EIGRP configurations into your post?

3. "show ip eigrp top act" does this command on the routers that are hanging onto this route show this 172.16.20.0/24 as Active?

There are a couple of EIGRP code defects that could be causing this. The above added information should help id the problem for you.

Regards,

Don

New Member

Re: EIGRP Router Incorrectly advertising route

1 ---- 12.1(4), 12.1(7), 12.1(3a)XI5. 2 of them I will have to find out as I don't have pwds, but sho cdp neigh det shows that they are all at least 12.1 or 12.2. 2 ----- not sure what you are looking for. basically we have no auto summ on and the networks and sometimes a distribute list. We don't usually set metrics but I did just find this on one of the routers:

router eigrp 1

network 10.0.0.0

default-metric 4096 100 255 1 1500

no auto-summary

no eigrp log-neighbor-changes

3 ----- Checked 3 of the routers and none of them have active routes.

sho ip eigrp topo all-links shown here:

P 172.16.20.0/24, 1 successors, FD is 2698752, serno 75499390

via 10.240.215.4 (2698752/2696192), FastEthernet0/0, serno 75482507

via 10.240.150.18 (2878208/2750208), ATM2/0.2

via 10.240.150.14 (160369152/2801152), ATM2/0.8

via 10.240.150.26 (160369152/5241088), ATM2/0.7

via 10.240.150.2 (160369152/20241152), ATM2/0.9

via 10.240.150.10 (160369152/2801152), ATM2/0.6

THANKS !

Silver

Re: EIGRP Router Incorrectly advertising route

12.1.4 - 12.1.18 (the latest GD) there have been 82 fixes.

CSCdt15109, CSCdt32880, CSCdv85419, CSCdx65510 are but a few of the more nasty ones.

Once classless support was added to EIGRP in IOS there were problems. So, I would recommend you to research upgrading to a newer code. There are definately issues with 12.1.4 and 7.

Hope this helps,

Don

New Member

Re: EIGRP Router Incorrectly advertising route

Thanks for your help Don. I did look at those caveats, but none seem to accurately identify my problem except maybe 5109 which is very vague. We will probably upgrade to 12.1(18). Unless anyone else has other ideas ?

Silver

Re: EIGRP Router Incorrectly advertising route

Keep in mind I just outlined 4 of them that jumped out at me. There were 82 fixes, as stated. I can tell you, running 12.1.7, in a customer network we had major SIA, Summarization, and Routes getting stuck in the topology table issues. We upgraded (12.1.16 at the time) and all was good.

Thanks,

Don

New Member

Re: EIGRP Router Incorrectly advertising route

Agreed. The wierd thing is we have many other routers in the US that are at the same or even lower releases of code and we haven't seen this problem here. That's why I'm trying to figure out what is different and/or which router exactly is causing the problem. In our WAN some routers are at 12.1.7 but others that are running 11 code (major core routers where we can't get down time to upgrade, and don't have any issues with)

Silver

Re: EIGRP Router Incorrectly advertising route

11 version EIGRP is good to go and stable, although some of the new classless/stub/ SIA Query/ etc type features are not in them. Once the classless support was added in 12.1M there were problems. Good summarization, distribution lists filtering unneeded routes, etc will keep you out of trouble with EIGRP.

Hope this helps,

Don

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