[184019] in North American Network Operators' Group
Re: Service Providers behaviour for dual homed enterprises
daemon@ATHENA.MIT.EDU (Mark Tinka)
Thu Sep 24 09:47:33 2015
X-Original-To: nanog@nanog.org
To: William Herrin <bill@herrin.us>, Jason Bullen <jmbullen21@gmail.com>
From: Mark Tinka <mark.tinka@seacom.mu>
Date: Thu, 24 Sep 2015 15:47:24 +0200
In-Reply-To: <CAP-guGW18NDxK-VkNWTCEYcaj2PT9sdnab1ozFU6tg73AQafsw@mail.gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On 24/Sep/15 15:21, William Herrin wrote:
> Hi Jason,
>
> That's normal. Verizon does it too. Both have "community" tags which
> you can attach to your route advertisement. Each will have one that
> indicates they should give external routes the same "local pref" as
> the route you announce to them. Tagging your route announcement with
> the proper community will cause them to route based on AS path length
> as you expect.
Depending on the provider, this can't always be guaranteed, i.e., that
the available LOCAL_PREF values a customer can trigger via a BGP
community support anything <=3D what routes the network considers "extern=
al".
What's possible (or available) may also be influenced by whether one's
upstream is "transit-free" or not, I imagine.
Mark.
