Routing – how to remove the OLD_Router-ID from ospf toplolgy table

cisco-iosospfrouterrouting

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?

Tnxall

Best Answer

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.

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Cisco – OSPF Area Backbone(0) is Inactive

Well, this is kinda funny. Firstly, I should mention that this is a project that I was recently asked to work on where everyone that previously worked on it has left the company and there is next to no documentation. All I had to go on was a grossly inaccurate network topology diagram which I am in the process of redrawing.

Anyway, after investigating a million other things, I traced the tremendous mess of cables behind the server racks to look at the multiple ethernet cables from the segment that wasn't talking to the rest of the network. This is where I saw no link lights for the ethernet ports on the back of a server whereas the front panel showed several green lights. What I found out is that the front panel of the server will show those green lights even when it isn't turned on! Since it was off, there was no active connection from that particular server rack to the rest of the network. After turning it on, I checked the router again and AREA 0 is no longer inactive. It now has its OSPF neighbors and routes that it should have and the end devices are able to communicate properly. So, everything works now that the server has been turned on.

In summary, one needs to always ask the following two questions:

Are you sure it's plugged in?
Have you tried turning it off and on again?

Cisco – OSPF LSA maximum age (max age) default value

OSPF MAXAGE is 3600 seconds (1 hour).

Quoting from RFC 2328 - OSPFv2; Appendix B "Architectural Constants"

MaxAge
    The maximum age that an LSA can attain. When an LSA's LS age
    field reaches MaxAge, it is reflooded in an attempt to flush the
    LSA from the routing domain (See Section 14). LSAs of age MaxAge
    are not used in the routing table calculation.  The value of
    MaxAge is set to 1 hour.)

Finally, a useful google query in case you're interested in how I found the first link... ospf lsa maxage

Best Answer

Related Solutions

Cisco – OSPF Area Backbone(0) is Inactive

Cisco – OSPF LSA maximum age (max age) default value

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