OSPF Router ID

[hs08]

Hi..

We have several interface ip address like in the picture, and why router id of my ospf is 10.103.242.5 and not using my loopback ip address?

[Giuseppe Larosa]

Hello @hs08 ,

OSPF RID is chosen when you configure the router ospf process .

if you have configured the loopback interface later the OSPF process will not use it as RID unless you restart the process with

clear
ospf <process-number>.

Another possible reason is if the loopback belongs to a different routing table / VRF.

Hope to help

Giuseppe

[hs08]

I already clear ospf process but still router id not use

 loopback ip addr

[MHM Cisco World]

clear ip ospf process

<< this will solve route-ID selection issue.

[hs08]

I already

 clear ospf process

but still router id not use my

 loopback ip addr

[MHM Cisco World]

let me check this issue, I will lab and update you after 1 hour

[hs08]

Hi @MHM Cisco World 

noted with many thanks. Here i send my screen shoot of my ospf router id

[MHM Cisco World]

the loopback is down that why the OSPF not use it, 
no shut the loopback and

clear ospf process

 
do this and see result 

[hs08]

hi @MHM Cisco World 

Still same

[MHM Cisco World]

you are right, I try

clear ip ospf process 

and the ospf not elect Lo as route-id 

the only case that the ospf re-elect the router-id is by 

no router ospf x
router ospf x

[hs08]

Hi @MHM Cisco World 

Thanks for your lab. So below statement is not right?

OSPF Router ID selection algorithm works as below.
• Any manually configured OSPF Router ID in OSPF Process is selected as the OSPF Router ID.
• If there is no OSPF Router ID configured, the highest IP address on any of the Routers Loopback Interfaces is selected as the OSPF Router ID.
• If there is no Loopback Interfaces configured, the highest IP address on its active interfaces is selected as the OSPF Router ID.

[MHM Cisco World · Accepted solution]

now all above is right if you 

1- config interface ip
2- config Loopback 
3- finally config router ospf

but I think you do 

1-config interface ip

2- config router ospf

<<- when you add this command any new interface ip or lo not consider for election, because the ospf already elect router-id, here I lab check

 clear ip ospf process 

to see if ospf re-elect again but NO still ospf use the router-id of first election, and hence we need to shift this step to be step after config Lo and we can do that with no router ospf x then router ospf x

3- config loopback 

[balaji.bandi]

the pciture is missing the post, if you can share the output again - if the router-id manually added that will be updated LSA to all the neighbours automatically, but i would like to see the output, what is configured and what is not taking effective

router id choose as below process  :

OSPF Router ID selection algorithm works as below.
• Any manually configured OSPF Router ID in OSPF Process is selected as the OSPF Router ID.
• If there is no OSPF Router ID configured, the highest IP address on any of the Routers Loopback Interfaces is selected as the OSPF Router ID.
• If there is no Loopback Interfaces configured, the highest IP address on its active interfaces is selected as the OSPF Router ID.