Change the OSPF process id without any restart of your router

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Sometimes we've faced with a Cisco router that was configured with OSPF routing protocol and it is operational.

Router1# show ip ospf neighbor

Neighbor ID     Pri    State      Dead Time    Address     Interface
192.168.45.1    1      FULL/DR    00:00:36     10.0.0.1    Ethernet0

Router2# show ip ospf
OSPF is running, process id: 1, router id:192.168.45.1

Regarding of router-id selection on router if you change the IP of loopback or physical interfaces on the router, router-id remains same and if you try to reset the process of OSPF by (clear IP OSPF process), there is no change on router-id would be occurred.

Referring Cisco articles and books there is only one way to reset router-id and you should restart your router to effect your configuration on OSPF id.

I've found a trick to reset router-id to new value (highest IP address of loopback or physical interfaces) without any restart of your router.

You should only set a temporary router-id on OSPF process on your routers and then remove it (them). By this action the OSPF process id would be set to highest IP address of loopback interfaces if it's available in other hand highest IP address of physical interfaces.



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