EIGRP Router ID - not using loopback

wavewave Member Posts: 342
Hi there,

I'm doing an EIGRP lab right now and I have a loopback on R1 of R1 and R2 are connected via serial connection on the network and the neighborship has been formed, routers have been exchanged...

R2 sees R1's router-id as instead of the loopback address

Everything I've read has told me that if the RID is not explicitly configured, EIGRP will select the highest loopback address first for the RID. If there is no loopback then it will select the highest IP address on an up/up interface.

Has anyone else come across this?

EDIT: I think I misinterpreted this...

I just did a:

R1#sh ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(

Then on R2:

R2#sh ip eigrp neighbors
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num
0 Se1/0 13 00:12:11 45 2280 0 6

I had always thought "Address" was the RID, but it must be the IP the neighbor is using to communicate.

ROUTE Passed 1 May 2012
SWITCH Passed 25 September 2012
TSHOOT Passed 23 October 2012
Taking CCNA Security in April 2013 then studying for the CISSP


  • SubnetZeroSubnetZero Member Posts: 124
    You got it!

    In Cisco IOS Software Release 12.1 and later, the show ip eigrp topology command shows the RID.

    With OSPF you can see your neighbors RID with the "show ip ospf neighbors" command under Neighbor ID

    R1(config-if)#do sh ip o n
    Neighbor ID Pri State Dead Time Address Interface 1 FULL/DR 00:00:38 FastEthernet0/0


    While no trees were harmed in the transmission of this message, several electrons were severely inconvenienced
Sign In or Register to comment.