[174816] in North American Network Operators' Group
Re: cogent update suppression, and routing loops
daemon@ATHENA.MIT.EDU (ryanL)
Thu Oct 2 12:45:01 2014
X-Original-To: nanog@nanog.org
In-Reply-To: <CAPwoXyujea2d9TJw==Z4phEjAQaVNL6megU26FOrR0qV0cYJQQ@mail.gmail.com>
Date: Thu, 2 Oct 2014 09:44:26 -0700
From: ryanL <ryan.landry@gmail.com>
To: Peter Persson <peter.persson@bredband2.se>
Cc: North American Network Operators Group <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
i still advertise the aggregate as a backing route. one reason i might like
advertising a /24 is (usually) it's a nice way to gently attract return
traffic down a certain path so i can do maintenance on the other side.
plenty of other ways to do this, i know (prepending, communities, etc).
On Thu, Oct 2, 2014 at 9:17 AM, Peter Persson <peter.persson@bredband2.se>
wrote:
> Just a stupid question.
> Why do you announce a /24 of a /22? Why not announce the whole /22
> directly?
>
> Regards,
> Peter
>
> 2014-10-02 18:03 GMT+02:00 ryanL <ryan.landry@gmail.com>:
>
>> hi. relatively new cogent customer. is what i've stated in my subject line
>> kinda standard fare with them?
>>
>> i've discovered that when i advertise a /24 from inside a larger /22 to
>> XO,
>> (who peers with cogent), and then pull the /24 some time later, that
>> cogent
>> holds onto the /24 and then bounces packets around in their network a
>> bunch
>> of times for upwards of 8-10 minutes until they finally yank it. this
>> effectively blackholes traffic to my /24 for anyone that is using a path
>> thru cogent.
>>
>> example: http://ryry.foursquare.com/image/0e0K1K0t0W2M
>>
>> it's been a bit of a frustrating experience talking to their noc to
>> demonstrate it, but i'm able to duplicate it on demand. even pushing
>> routes
>> using their communities to offload the circuit takes forever to propagate
>> even on their own looking-glasses.
>>
>> thx
>>
>> ryan
>>
>
>
