After explicitly assigning a Router-ID to the ospf process the "old RouterID" remains in the topology table of the whole ospf area.

How can I remove the old router ID? What is the max age for it? (3600??) Wont this entry cause any problems?


  • The router ID will stay until the OSPF process is restarted.
    – Ron Trunk
    Feb 7, 2016 at 13:16
  • Hi, pls take a look at the comment below (4 maupin)
    – ae41
    Feb 13, 2016 at 3:58
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 7, 2017 at 19:07

1 Answer 1


You need to use the clear ip ospf process command after you change a router ID. Alternatively, you could just restart the router, but that seems extreme.

  • Hi, restarting the ospf process (or router) will cause the router to use the new RID. Up to this point you are right, but the problem is with the old RID remaining in the topology table of the other routers in the area (and uploaded into the newly bootup router when forming adjacencies). It seems the other routers think there is a router with the old ID some where in the network. So how can I remove the old RID? tnx for your time in advance
    – ae41
    Feb 13, 2016 at 3:54
  • It times out with the ip ospf dead-interval. By default, OSPF uses a 10-second hello-interval and 40-second dead-interval on broadcast and point-to-point links, and a 30-second hello-interval and 120-second dead-interval for all other network types. These intervals can be adjusted, but they must match on each router on a link in order to form a full adjacency.
    – Ron Maupin
    Feb 13, 2016 at 4:41
  • Hi, and tnx for the quick reply. This does not have to do with the hello timers that you mentioned.As I have mentioned the old RID remains in the topology table of the whole area (you can check it out in a simple gns3 lab).
    – ae41
    Feb 13, 2016 at 5:12
  • When a dead-interval is reached without receiving a hello, the neighbors will know that the router is unreachable. I don't understand your problem. This is how OSPF works.
    – Ron Maupin
    Feb 13, 2016 at 5:24

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