Router ID in EIGRP

Unanswered Question
Dec 22nd, 2008

Hi,

I am trying to understand this thing:

In EIGRP loopback IP address will be the RID for that router right?

if yes then when i m doing sh ip eigrp neig i see some different interface IP address as a neighbor address in that table! then i tried to configure RID for eigrp using eigrp router-id command but condition is still as it is!!!

regards

Devang Patel

I have this problem too.
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csco10716389 Mon, 12/22/2008 - 21:25

A rediculous issue , as u know there must be no any way other than soft reboot , it should pull out the RID after this.

Rupesh Kashyap Mon, 12/22/2008 - 21:40

Hi I am also facing the same problem.. R u finding any thing in SH IP Eigrp Topology

devang_etcom Mon, 12/22/2008 - 22:09

I am trying to find out the update packet format to look for Router ID field in update packet!!! let see!!!

wait for other expert replies!!!

regards

Devang Patel

cameron.moody Mon, 12/22/2008 - 23:15

Hi,

Yes the RID will be the highest loopback IP unless you have configured the RID manually.

When you do the show ip eigrp neighbor command it is shows the IP address NOT the RID of that router. You can use sh ip eigrp topology to see RIDs though.

BTW here is a link with some captures of various EIGRP stages. This is a very handy site I have found and really top notch info as well!

http://packetlife.net/captures/protocol/eigrp/

Here's an article on configuring the RID and troubleshooting if you have duplicate RIDs that are the same.

Giuseppe Larosa Tue, 12/23/2008 - 00:02

Hello Devang,

EIGRP RID is a later add to the protocol that has distance vector origins.

For this reason the sh ip eigrp neighbors will show you the interface ip addresses and not EIGRP RIDs.

OSPF and IS-IS that are link state make a more deep usage of RID and they identify the nodes with their RIDs.

What you see is normal behavior for EIGRP.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094613.shtml#n

the only issue is if RIDs are duplicated see

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800949ab.shtml

I don't think you can see RID in EIGRP updates you can see it in sh ip eigrp topology.

The only exception are EIGRP external routes that contain an originating router field where the EIGRP RID of the redistributing node is placed.

In fact, also the example about duplication involves a redistribution.

So EIGRP RID use is limited compared to OSPF and IS-IS.

Hope to help

Giuseppe

guruprasadr Tue, 12/23/2008 - 00:21

HI Devang, [Pls RATE all Informative POST]

The EIGRP router ID is normally selected in the same manner as Open Shortest Path First (OSPF). The highest IP address assigned to a loopback interface is selected as the router ID. If there aren't any loopback addresses configured, the highest IP address assigned to any other interface is chosen as the router ID.

Refer link below:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800949ab.shtml

Hope I am Informative.

Best Regards,

Guru Prasad R

guruprasadr Tue, 12/23/2008 - 01:05

HI Giuseppe,

Congratulations for the new Badge on your profile.

Best Regards,

Guru Prasad R

devang_etcom Tue, 12/23/2008 - 09:23

Thanks experts for your inputs!!!

but there should be one more field in show output for neighbor router id, that makes management of neighbors easy!!!

regards

Devang Patel

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