BGP Local AS


The local hedgehog protection foundation is merging with the local Fox protection program. The networks are connected through BGP and part of the migration means you have to change your AS number. You don’t mind doing this but you don’t want to break the BGP neighbor adjacency.


  • All IP addresses have been preconfigured for you.
  • Configure EBGP on router Sonic and use AS number 1.
  • Configure EBGP on router Tails and use AS number 2.
  • You have to configure router Tails with the “neighbor remote-as 100” command.
  • Ensure your EBGP configuration is working.




BGP Local AS

Video Solution:

Configuration Files

You need to register to download the GNS3 topology file. (Registration is free!)

Once you are logged in you will find the configuration files right here.

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Written by René Molenaar - CCIE #41726

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René - CCIE #41726 is the creator of where he shares CCNA, CCNP and CCIE R&S labs. He also blogs about networking on


  1. I downloaded the file,and checked it. But there is only interfaces configured in it.
    Then I tried to do it myself.
    On Sonic:
    router bgp 1
    neighbor remote-as 2

    On Tails:
    router bgp 2
    neighbor remote-as 1

    I remember that a router could run rip at first and then configure eigrp on it. After the eigrp learns the whole topology, you could delete the configuration of the rip without stopping the network. So I guess maybe I could configure “router bgp 1”, and then, “router bgp 100” finally, using “no router bgp 1”
    But after I entered the command “router bgp 100”, it shows “BGP is already running; AS is 1″”

    So would you please tell me the answer? Thanks 🙂

  2. Hi Mao,

    The key to this lab is the BGP “Local AS” feature. You can advertise a different AS number to a neighbor than the one you have configured with the BGP router process.


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