EIGRP Debug AS number


One of your colleagues is on vacation and forgot to document the EIGRP topology before he left. You need to add another EIGRP router but you have no idea what the autonomous system (AS) number is of the other routers. Unfortunately you are unable to look it up but you do know that authentication is not enabled. With a bit of luck you might be able to debug your way out of this one!


  • All IP addresses have been preconfigured for you.
  • EIGRP has been preconfigured for you on router John.
  • Use a debug command on router Jack to retrieve the EIGRP AS number.





Video Solution:

Configuration Files

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Written by RenΓ© Molenaar - CCIE #41726

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About the Author: Rene Molenaar

RenΓ© - CCIE #41726 is the creator of GNS3Vault.com where he shares CCNA, CCNP and CCIE R&S labs. He also blogs about networking on http://networklessons.com


  1. gotcha!!!

    Jack(config-router)#*Mar 1 00:01:27.271: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 12: Neighbor (FastEthernet0/0) is up: new adjacency

    donot want to spoil fun, hence not revelaing the way.


  2. totally stumped – tried every iteration of the debug ip eigrp and debug eigrp I could think of

    I can wireshark it in oh, 10 seconds πŸ™‚ – but I am not finding an appropriate debug command – the closest I get is debug eigrp packet, which gives me the hellos I’m sending out, but not ones I’m receiving – I can only presume they’re being discarded because the AS is configured wrong –


    1. Hint: If there is an AS mismatch, received eigrp packets are silently discarded, so you will not see them using debug eigrp commands πŸ˜€

      1. ach – we’ll I tried multiple ip packet debugs too – and tried debugging with an ACL and debuging multicast packets and eigrp without eigrp config – breaking my heart πŸ™‚

        1. ok – ran it by my coworker and after about 2 hrs he got the answer – I googled like heck and ran searches thru Safari books – that was just gruesome though – LOL

  3. Hi

    Ok so i think i got it figured out how can i find ot if i am correct?

    Thanks for a great lab took me 2 hours to figure this out

    1. For now just check the config on the other router to see the AS number. I’ll have to record the video for this so you can see how I’m doing it πŸ˜‰

  4. I have searched for the answer but nothing. Can you give or email it to me ?

  5. I got it and resolved the case with undocumented debug command πŸ™‚
    This lab is quite challenging.

  6. Hi Rene,
    How do you load the lab or topology (you said it is preconfigured) into GRS and start working on it?
    Thank you

      1. Hi Rene,
        Can you please send the the whole list of written solution so that I can print it out. Your video solutions are great but I need to have an Internet connection everytime I need some help. I would be a great help.


    1. It will probably take a long time before this will happen πŸ™‚ what about the video? I walk you through the configuration there.

      1. The videos are great but its just that I am practising at a place where there is no internet at the moment n if i can grab something on the paper it would be much easier for me to practise. So I would request if you can start off with few solutions at your convenience and update it whenever you can.
        [b]AGAIN its just a request.[/b] What all you are doing here should be enough for people like me and I appreciate your help so far.
        Looking forward to hear from you soon.


        1. Ah I see…so you would like to see the configurations together with some explanations of how/why i’m doing it?

    1. The .CFG files contain the configuration of the routers. The .NET file is the actual topology.

  7. Got it, May be I am better user of google.. got it in 5 mins πŸ™‚

    Rene, from where u get these ideas?? Nice lab.. thanks..

    1. Most of the labs I create after reading books or googling around for information πŸ™‚

  8. Hi Rene,

    I didn’t expect this lab to be that challenging, but it was good exercise.

    i was able to find AS number by using access-lists.


  9. How do i go about opening this file? When i unzip the files, i only see the cfg files for the routers? When is the *.net file?

  10. [b][size=large][color=red]hey brozzz don’t get tension here we got a command for that

    #debug ip packet detail dump

    after that here will u r next side autonomuse number in hex and than convert it .

  11. I have to admit that I had to check your video for the answer Renee,
    this one is really tough.

  12. I also added the conditional debug before enabling the debug access-list. It’s not necessary in this lab, but it could be useful in the production environment.

  13. HI Rene, I am ccna Certified and now Preparing for CCNP ROute. Your labs are always helpful so I am at your website now.. I worked out on your Lab DebugEigrpAS. I configured it in right way .. but i did not understand why you use Access-List though the objective of the Engineer can be fulfilled only by giving #debug ip packet dump

    please make me understand and clear my confustion..
    thanks in advance…

    Sanjeev K Rana

    1. I haven’t seen the video but i would guess Rene used the the [b]debug ip packet [access-list number] dump[/b] to catch EIGRP packets only (which again i would guess would look something like [b]access-list 100 permit ip any log)[/b]

      But yes you’re right, the objective could be accomplished by issuing the debug ip packet dump.

      Hope this helps

  14. Keep it up Rene. Am leaving a comment in this lab but it goes to all ur labs also.
    Maybe its a small action from your side or sometime u r fed up of posting these wonders, but for us out here, its a huge kick in enhancing our knowledge. Thx. Cheers

  15. How to download the topology?
    There isn’t and link to download even after login.
    please help..

  16. Definitely thought it would have come in one of the standard EIGRP debugs. Nice lab. πŸ™‚

  17. Very nice! Thanks Rene for the video.

    Anyway, I just wanna ask how did you know that the ones with succeeding zeroes contains the AS number of EIGRP?

    Thanks a lot!

    1. Hi Kat,

      I looked it up somewhere. Not sure what the exact logic is behind it but i’m sure there is something πŸ˜‰


  18. Hey, I am getting error while opening the startup config file.

    “Cx_freeze, python script error.

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