[68607] in North American Network Operators' Group
Re: Load Balancing Multiple DS3s (outgoing) on a 7500
daemon@ATHENA.MIT.EDU (Patrick W.Gilmore)
Mon Mar 15 02:18:11 2004
In-Reply-To: <Pine.LNX.4.44.0403132154530.11205-100000@server2.tcw.telecomplete.net>
Cc: Patrick W.Gilmore <patrick@ianai.net>
From: Patrick W.Gilmore <patrick@ianai.net>
Date: Mon, 15 Mar 2004 02:17:32 -0500
To: nanog@merit.edu
Errors-To: owner-nanog-outgoing@merit.edu
On Mar 13, 2004, at 4:57 PM, Stephen J. Wilcox wrote:
>> He'll be okie. It's just a little difficult for BGP to "load balance"
>> outbound bits when the bulk of the Internet these days is 2 AS hops
>> away from each of four upstreams. Not impossible, but it doesn't
>> happen by default either.
>
> I used to do this ages ago, I did it by setting MEDs on the incoming
> BGP
> prefixes, in my route-maps I arbitrarily gave some nets (/8s or
> smaller) lower
> med on one feed and higher on the others to influence path selection.
>
> I shy away from anything but the gentlest of tweaks so I personally
> wouldnt mess
> with as-path, localpref, weight etc
Yeah, probably a good idea not to use Weights, but not sure about
AS_PATH. Nothing wrong with a prepend here or there, IMHO. :)
But also nothing wrong with setting the MEDs if you like. Just be fore
to have "always compare MED" on, or MEDs between multiple providers are
not useful (which you obviously had set or this wouldn't work).
I kinda like setting the origin code. No one pays attention to it, but
it is in the selection criteria. that way you can use MEDs from the
same provider and still influence routes between providers.
--
TTFN,
patrick
