[Xorp-users] Question regarding xorp BGP

[Stegen Smith]

Hi Atanu,

When I receive updates from my peer, they strip out their AS from AS_PATH when they send me the updates.
Obviously, as experienced,  this can cause some issues without a way to get around it in xorp.  I'm guessing my peer
isn't the only one who behaves in this fashion as cisco has no bgp enforce-first-as, juniper has no bgp enforce-first-as,
and openbgpd also the enforce neighbor-as no configuration options.  It'd be cool to be able to have this functionality
with xorp as well.  If this is do-able, then that'd be awesome.

I hope that helps, and let me know if you need anymore information.

thanks!
stegen
Atanu Ghosh wrote:
> Hi,
> 
> If the AS numbers of the local and remote BGP are not equal then BGP
> considers the peering to be an external peering
> and the leading AS number in AS path must match the AS number of the
> peer. The error that you are seeing is what you would expect if there
> has been a mismatch. The XORP BGP does not have a flag to disable this
> check. The only way to disable the check is to form an internal
> peering by using the same AS number locally and remotely.
> 
> What is your peer doing that you need to disable the check?
> 
>        Atanu.
> 
> On Mon, Feb 9, 2009 at 5:38 PM, Stegen Smith <stegen at owns.com> wrote:
>> Hello Group,
>>
>> It's been a while... had my head down with some other tasks for a few months there, but now get to return to
>> the world of checking out xorp.  Anyways... I've got a question, perhaps feature request, about xorp's bgp
>> configuration/implementation.
>>
>> I've got a peer that I want to peer up with; however, they do some trickery which causes xorp_bgp to not want to
>> form an adjacency.  Here's the log snippet:
>>
>> [ 2009/02/09 17:08:56 INFO xorp_bgp BGP ] Sending: Notification Packet: UPDATE Message Error(3): Malformed AS_PATH(11)
>>
>> The configuration looks proper to me, and  I'm able to get my openbsd systems able to connect using the 'enforce neighbor-as no' in openbgpd.
>> So, I was wondering if this option is available to me, or if there's some trickery to make xorp_bgp to form an adjacency to a neighbor
>> whose left most AS doesn't match its remote AS value?  It doesn't seem that there is something like this in the manual, so I am asking the
>> group.
>>
>> I hope I was clear enough, if not, please let me know and I'll try to provide more information.
>>
>> thanks!
>> steen
>>
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>