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New Member

ospf router id problem


I have a 3660 router which is connected to various sites on E1 question firstly is is router id duplication a problem? secondly following are the messages i got

Mar 22 12:18:15: %OSPF-4-DUP_RTRID_NBR: OSPF detected duplicate router-id from on interface Serial2/1:1

Mar 22 12:32:06: %OSPF-5-ADJCHG: Process 20, Nbr on Serial2/1:1 from LOADING to FULL, Loading Done

Mar 22 15:55:29: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/1:1, changed state to down

Mar 22 15:55:29: %OSPF-5-ADJCHG: Process 20, Nbr on Serial3/1:1 from FULL to DOWN, Neighbor Down: Interface down or detached

Mar 22 15:57:09: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/1:1, changed state to up

Mar 22 15:57:11: %OSPF-5-ADJCHG: Process 20, Nbr on Serial3/1:1 from LOADING to FULL, Loading Done

i checked the remote router at serial 2/1:1 and its router id was ,so why did i get this message of router id duplication.

Any help?


Re: ospf router id problem

If OSPF detects duplicate router-ids, routing maynot work properly.

On a router, give "show ip ospf" command and it will show the router-id for the OSPF process on the router. Check that on both the neighboring routers. It is also possible that the neighbor router's router-id is fine, and some other router in your network has the same router-id as this router. Give "sh ip ospf database" and check for duplicate router-ids.

Also, remember after you change a router-id, I believe, you need to restart the OSPF process or reboot the router.

New Member

Re: ospf router id problem

I did a show ip ospf at the router .

Router#show ip ospf

Routing Process "ospf 20" with ID

Supports only single TOS(TOS0) routes

Supports opaque LSA

so apparently this router doesnt even have that id which the log says is cause of duplication


Re: ospf router id problem

I have seen this many times before . This error messaged showed up in your log because the carrier had a loop on the line on Serial2/1:1 back towards your router with the RID , It was seeing itself in its hellos and declared a Dup RID . It this messages has ceased , I would not worry about it.

New Member

Re: ospf router id problem

This could be a bug if your router is ASBR.

CSCdu71404 Bug Details


 %OSPF-4-DUP_RTRID_AS: Router may wrongly complain about duplicate







Duplicate of






First Found-in Version

 12.2(2)   All affected versions

First Fixed-in Version

 12.2(3.4), 12.2(3.4)T, 12.2(3.5)S, 12.2(3.4)B, 12.1(10.1), 12.2(4.02a)DA, 12.1(10.5)E, 12.1(10.5)EC  Version help

Release Notes


An ASBR (non-ABR) may wrongly complain about "%OSPF-4-DUP_RTRID_AS: Detected

router with duplicate router ID". This is a misleading informational message

but does not cause any adverse problems to the router.

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