[153145] in North American Network Operators' Group
Re: HE.net BGP origin attribute rewriting
daemon@ATHENA.MIT.EDU (David Barak)
Thu May 31 08:35:12 2012
In-Reply-To: <20120531.140300.74687292.sthaug@nethelp.no>
From: David Barak <thegameiam@yahoo.com>
Date: Thu, 31 May 2012 08:33:27 -0400
To: "sthaug@nethelp.no" <sthaug@nethelp.no>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On May 31, 2012, at 8:03 AM, sthaug@nethelp.no wrote:
>> I disagree. Origin is tremendously useful as a multi-AS weighting
>> tool, and isn't the blunt hammer that AS_PATH is.
>=20
> If you think of AS_PATH as a blunt hammer, how would you describe
> localpref?
>=20
> We use AS_PATH in many cases *precisely* because we don't consider it
> to be a blunt hammer...
>=20
So you're connected to providers A and B, who in turn connect to C. Additio=
nally, B has customer D.
If you set origin E toward B (leaving origin I toward A) you influence C's d=
ecision without affecting either B or D, and you ensure that C still learns b=
oth routes to you. It's a more subtle nudge than as-path.
In general, I prefer routinely using attributes that are further down the al=
gorithm so at the big guns can be saved for when they're needed or for speci=
al policy issues.
David Barak
Sent from a mobile device, please forgive autocorrection.=
