[110826] in North American Network Operators' Group
Re: Single carrier multi-circuit asynchronous routing issue
daemon@ATHENA.MIT.EDU (Aaron Millisor)
Tue Jan 20 13:21:30 2009
Date: Tue, 20 Jan 2009 13:21:32 -0500
From: Aaron Millisor <aaron.millisor@bright.net>
To: =?ISO-8859-1?Q?Anders_Lindb=E4ck?= <list-only@dnz.se>
In-Reply-To: <914FFB80-2AFA-4D0C-AFE1-4F4B5A09FCFD@dnz.se>
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
Thank you both. Strict mode uRPF was indeed the problem. Took awhile for
them to fix it for me, but at least it's fixed.
-- am
Anders Lindbäck wrote:
> On 7 jan 2009, at 21.05, Niels Bakker wrote:
>
>> * aaron.millisor@bright.net (Aaron Millisor) [Wed 07 Jan 2009, 20:53
>> CET]:
>> [..]
>>> If I were to prepend the network 1.1.1.0 to come in on 'sprint 1',
>>> but have a route to 2.2.2.0 via 'sprint 2' so that traffic comes in
>>> on one circuit but returns on the other, routing is broken. If I
>>> change my route so that packets directed to 2.2.2.0 return on the
>>> same circuit that the traffic is received on, everything works fine.
>>
>> You might be running into uRPF (unicast reverse path forward
>> verification).
>>
>>
>> -- Niels.
>>
>
> Strict-mode uRPF will couse this, I am sure sprint support can help you
> with it..
>
> ------------------------------
> Anders Lindbäck
> anders.lindback@dnz.se
>
>
