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This Question is Not Answered 1 Correct Answer available (4 pts) 2 Helpful Answers available (2 pts)
3777 Views 2 Replies Latest reply: May 19, 2010 9:24 PM by Angela RSS

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OSPF Authentication Question - keyid

May 19, 2010 7:17 PM

TheOtherTomJones, CCNA, CCDA, CCNAS 317 posts since
Sep 6, 2009

OSPF authentication is configured with the following:


  • ip ospf message-digest-key keyid md5 key (used under the interface)

  • area area-id authentication message-digest (used under "router ospf <process-id>")


Is there any significance to the keyid portion of the command?


Is the keyid an arbitrary number or is there a reference for specific meanings to certain numbers like privledge levels, etc.


Its kind of a stupid question but this is the first time Ive been exposed to OSPF authentication.

  • Scott Morris - CCDE/4xCCIE/2xJNCIE 8,427 posts since
    Oct 7, 2008

    Very much so.   it's taken in as part of the equation to come up with the MD5 hash, so if you don't match the number, then you'll run into problems!


    One of the cool things with MD5 keys in OSPF is that you can have multiple keys on the same interface for different peers.


    Hub/spoke is a nice way to see this....


    Hub can have key 1 = cisco and key 2 = ccie

    spoke 1 has key 1 = cisco

    spoke 2 has key 2 = ccie (even though this is the ONLY key defined, it must be #2)


    Try it!  Play!


    Run your debugs, let the router tell you what it likes and doesn't like!



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  • Angela 746 posts since
    Jan 29, 2010



      Just a note: OSPF keys has nothing do to with key chains, so lots of troubles saved, yeay! Also, when N keys are in use, N duplicates of a single packets will be send.




      To Scott: I think I might had a time using different OSPF key numbers and actually worked, I'm not absolutely sure so I will rerun the lab to confirm.

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