EIGRP Router ID

(Rene Molenaar) #1

This topic is to discuss the following lesson:

(Mauro P) #2

Great stuff Rene,

This tshoot is the ones to push our hairs out. Is very hard to spot. But on the other hand is very hard for 2 neighbors to have the same ID. But the debug was a Abracadabra on this story. Nice article. Will wait for more on eigrp if there is more. :slight_smile:

Mauro P

(Rene Molenaar) #3

Hi Mauro,

This is indeed a pain to troubleshoot, it’s not the first thing you would think of. There’s a small chance that you would encounter this on a production network…it’s a typical troubleshooting scenario for a lab.

More EIGRP material is on the way…

Rene

(Sahil B) #4

Hello Rene,

Can you please elaborate, what does this command do

redistribute connected metric 1 1 1 1 1

(Rene Molenaar) #5

Hi Sahil,

This redistributes directly connected interfaces into EIGRP. When you configure redistribution, you have to manually configure the metric that you want to use.

These examples might be helpful:

Introduction to redistribution

Redistribution between EIGRP and RIP

Rene

(Elliott F) #6

Great lesson. Until now I always assumed that EIGRP router IDs had to be unique.
And that it blocks redistributed routes is something that has to be seen to understand.

Just ran through the lab in GNS 3 and it seams that in IOS 15.x the show ip eigrp events command is no longer “hidden”.

(Trust_the P) #7

This is why I signed up for this site. “show ip eigrp events” is very useful.
Thanks Rene and Laz for your contents

1 Like
(Fabio P) #8

Hi Rene,

I did a Lab, and configured the same Router ID on both routers, I ran “clear ip eigrp neig”, but the srouters continue to learn routes with same router ID in both.

Thx…

(Lazaros Agapides) #9

Hello Fabio

This is expected behaviour. Like Rene mentioned in the lab, unlike OSPF, EIGRP doesn’t care if it the router ID is the same or not. It will still exchange routes normally and will function correctly.

The only exception to this rule is when we have an external or redistributed route. If R1 for example receives such an external route from R2 (which is running a second routing protocol such as OSPF for example), and if R1 and R2 have the same router ID, only then will R1 reject the route from R2.

I hope this has been helpful!

Laz

(Trust_the P) #10

Hello @fabio.hperez85, to test the issue of having same router IDs, you can create a loopback1 on R1 and redistribute it into eigrp (not advertising it):

int lo1
ip add 11.11.11.11 255.255.255.0
exit

router eigrp 1
redistribute connected
exit

If you run **show ip route eigrp** on R2, you won’t see this loopback 1 installed.