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Re: Level3 (3356/3549) changes routing policy
From: Adrian M <adrian.minta () gmail com>
Date: Thu, 2 Aug 2012 16:55:26 +0300

Better to use communities instead.
On Aug 2, 2012 11:34 AM, "Fredy Kuenzler" <kuenzler () init7 net> wrote:

From my observation Level3 has recently changed their routing policy. It
seems that 3356 always prefers customer prefixes of 3549, regardless of the
AS path length. Example (seen from 3356):

3549_13030_[Customer1]_[**Customer2]

is preferred over

2914_[Customer1]_[Customer2]

Considering that both 2914 and 3549 are peers of 3356, and 13030 is a
customer of 3549, 3356 seems to give higher local-pref on the longer
AS-path, likely to increase traffic and revenue of their sister network
3549.

Certainly it's common practice to overrule the BGP4 default behaviour, and
widely used by smaller networks.

Still I'm surprised that it happened obviously rather undetected, at
least, to my knowledge, Level3 did implement it silently and hasn't
published an official statement or customer announcement, which I think,
would have been fair, at least.

Considering that Level3 3356 and 3549 are by far the largest networks
globally this decision must have a large impact on traffic flows and, of
course money flows.

Maybe the BGP monitoring experts (aka Renesys et al) can shed some light?

--
Fredy K├╝nzler
Init7 / AS13030




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