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Forum Replies

  1. navn1 says:

    Good Stuff.

  2. Thanks for streamline it.

  3. Renee

    Hope you are well - can you tell me please if I configure a router ID on my router in OSPF which i just did on one of the GNS3 Vault Labs .... do I also have to specify that router ID or configure it also as a Loopback interface ? Anyway I just configured the router ID and it was preferred to the existing L0 address which I expected but not sure if it also needs to have its own address space on the router elsewhere ?



  4. Renee

    Hoe gaat het in Nederland meneer

    I have a question please on the use of the router ID - the question is this ... when I DO NOT configure a router ID on my OSPF routers in my lab network BUT I AM using Loopback interfaces (and as expected given OSPF rules) my single Loopback interface(s) (with Loopback 0 only configured per router) ... will be used as the router ID .. so no problem there ... however when I configure a unique and different router ID, i.e. NOT my loopback interface 0 .... as my router ID this will become my dominant 'neigbor ID' presumably when forming adjanceies with other routers .. again no problem i think ! in terms of understanding the concept .. however my confusion begins in terms of understanding why (as i have seen in a few working exmaples) anybody would use a router ID that was different to your loopback interface ID or best loopback interface .... this being from the perspective of 'loopback interface' is regarded as the king of interfaces in ospf right ?? so what advantage if any would one have or even disadvantage of configuring a router ID that was different to your actual loopback (or highest) llopback interface ?

    Many Thanks

    Will V

  5. William,
    It is considered best practice always to set the OSPF router-id manually, whether you happen to have a loopback or not. The reason for this is because there are certain OSPF functions that will break should the Router-ID ever change (an OSPF virtual link is a great example of this). If you rely on OSPF automatically choosing its Router-ID based on a loopback you have configured, this is no guarantee that the Router-ID wouldn't change later (for example, you later needed another loopback for some other purpose, and this new loopback had a higher IP address than the first).

    If you get into the habit of immediately setting the OSPF router-id as soon as you create the routing process, you will do yourself favors in the long run.

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