Level3 (3356/3549) changes routing policy

Thu Aug 2 13:55:26 UTC 2012

Better to use communities instead.
On Aug 2, 2012 11:34 AM, "Fredy Kuenzler" <kuenzler at 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 Künzler
> Init7 / AS13030
>
>