Simple OSPF question

bobobbobob Member Posts: 8 ■□□□□□□□□□
I'm wondering what your opinions are on this one.

I know the OSPF router ID is chosen as the highest IP address of the active physical interfaces or the highest loopback address if assigned. However, Lammle's book asks the question and gives the answer as "highest IP address of any logical interface".

Is this right? Loopback interfaces are only a subset of all logical interfaces, so for example, would the highest IP address of some other type of logical interface (ie non-loopback, eg tunnel) interface be used as the OSPF router ID?

Confused about this one icon_scratch.gif


  • pandimuspandimus Member Posts: 651
    Does he happen to mean mac address?
    Xinxing is the hairy one.
  • hotwiredhotwired Member Posts: 5 ■□□□□□□□□□
    I was wondering the same thing. Todd lammell's book says highest ip address of any interface and the xxxxxx example question I have says the highest ip address of any PHYSICAL INTERFACE??
  • pandimuspandimus Member Posts: 651
    Please dont refer to that website. (BRainDump
    We who come to know of this site as home deter against such brain **** sites..

    There are plenty of sites that you Can learn from rather than just get the answers to the tests...

    But to be honest with you i am not sure.. You will probably have to wait for one of the CCNA guys's to answer this one..
    Xinxing is the hairy one.
  • bobobbobob Member Posts: 8 ■□□□□□□□□□
    I think as prospective CCNA's were only supposed to know about one logical interface - the loopback, in which case the question and answer D make sense (sort of).
  • WebmasterWebmaster Admin Posts: 10,292 Admin
    The highest IP address on the router is used as the ID. If a loopback address is configured it will be used regardless if it is higher or lower. If multiple loopback address are configured the highest will be used.

    This allows you to define the Router ID by configuring a loopback address, on any router, regardless of the physical interfaces IP addresses.

    Do yourself a favor Throw away the PDF guide you are using. It is illegal, a violation of the NDA and copyright laws, and such products are usually filled with mistakes. In case you didn't realize, that PDF contains actual exam questions, hence, by reading them you are cheating, and by posting their name you are violating the Registration Terms to which you agreed when joined.

    You're lucky I'm not in my banning mood... (that's a joke folks ;))
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