OSPF duplicate Router ID

[salman-ahmad]

Hi,

I found these console messages in one core routers. I can understand the concept that router-id must be unique on OSPF router but thats why these kind of error messages we found on router console but what are the steps to quickly troubleshoot this kind of error configs are attached.

%OSPF-4-DUP_RTRID_AREA: Detected router with duplicate router ID 10.200.255.11 in area 91
NMS SYSLOG: Detected router with duplicate router ID 10.200.255.11 in area 91


%OSPF-4-DUP_RTRID_AREA: Detected router with duplicate router ID 10.200.255.12 in area 90
NMS SYSLOG: Detected router with duplicate router ID 10.200.255.12 in area 90

Kind Regards,

Salman Ahmed

[Giuseppe Larosa]

Hello Salman,

you can follow the document below

http://www.cisco.com/en/US/partner/tech/tk365/technologies_tech_note09186a0080117102.shtml?referring_site=smartnavRD

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080117102.shtml?referring_site=smartnavRD

you must fix this issue by changing the OSPF router-id on the device with a duplicated router-id

you can change the OSPF router-id manually by using

router ospf 10

router-id

But the first action is to find the device with duplicated router-id. However, you know from the logs that the local device (the one with the error message) is one of the two routers with the same router-id.

so you can change the OSPF router-id to a unique IP address unused in the network on this device instead of looking for the other devfce.

I recommend to use a loopback interface with IP address = new OSPF RID and to advertise the routerID IP addres in OSPF

This allows to reach the OSPF RID from everywhere in the OSPF domain

Hope to help

Giuseppe

[turnera]

Once you find the duplicates and change them, you will need to perform a 'clear ip ospf processes' on the two changed routers in order for the new router id's to be advertized as well. It will cause a reconvergence of your OSPF topology.