[117431] in North American Network Operators' Group
Re: Multi-homed implementation and BGP convergence time
daemon@ATHENA.MIT.EDU (Seth Mattinen)
Fri Sep 11 22:00:16 2009
Date: Fri, 11 Sep 2009 18:59:15 -0700
From: Seth Mattinen <sethm@rollernet.us>
To: nanog@nanog.org
In-Reply-To: <4AAADAFA.3060805@kl.net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Kevin Loch wrote:
> Seth Mattinen wrote:
>> Jay Hennigan wrote:
>>> "Tier 1", "tier 2" etc. are terms used primarily by salespeople, and
>>> don't have a lot to do with technical matters.
>>>
>>
>> Sure it does. If you're multihoming it will increase your AS path length.
>
> There is no general correlation between AS path length and whether
> or not a network pays to exchange traffic.
That has nothing to do with what I was trying to say. When one mixes
shorter/longer paths, you will generally see most of your traffic come
in via the shorter path.
It's like if I were to multihome with the local cable co (who has Level3
as an upstream) with a connection to Level3 myself. It's not likely that
traffic inbound to me is going to choose the longer route unless the
shorter one is down, and it's pointless as a backup because a regional
outage affecting Level3 may kill the cable co's link to them as well.
~Seth
