[107638] in North American Network Operators' Group
RE: why not AS number based prefixes aggregation
daemon@ATHENA.MIT.EDU (Paul Francis)
Mon Sep 8 15:31:32 2008
Date: Mon, 8 Sep 2008 15:31:18 -0400
In-Reply-To: <0F2D417A-DCB8-4232-9A2D-A6EFF27CE4B5@cs.ucla.edu>
From: Paul Francis <francis@cs.cornell.edu>
To: "Ricardo Oliveira" <rveloso@cs.ucla.edu>, <nanog@merit.edu>
Errors-To: nanog-bounces@nanog.org
This thread begs an interesting question: what is the right amount of
granularity for load balance? Folks here are saying that =
one-entry-per-AS is
too course...an AS wants to influence load on incoming links, and so it =
needs
multiple entries.
On the other hand, it is hard to imagine that we need hundreds of =
entries per
AS, or even dozens. So I'm curious...if we could wave a magic wand and
control the exact number of entries any AS needs to advertise, what =
would
folks consider to be roughly the right number of entries?
Thanks,
PF
=20
> -----Original Message-----
> From: Ricardo Oliveira [mailto:rveloso@cs.ucla.edu]=20
> Sent: Monday, September 08, 2008 1:11 PM
> To: nanog@merit.edu
> Subject: Re: why not AS number based prefixes aggregation
>=20
> Topological aggregation based on ASN is often too course=20
> granularity, see this paper:
> http://www.cs.ucla.edu/~rveloso/papers/giro.pdf
> specifically Fig4 is a good example, and sec 4C.
> Cheers,
>=20
> --Ricardo
>=20
> On Sep 8, 2008, at 6:20 AM, yangyang. wang wrote:
>=20
> > Hi, everyone:
> >
> > For routing scalability issues, I have a question: why=20
> not deploy=20
> > AS number based routing scheme? BGP is path vector=20
> protocol and the=20
> > shortest paths are calculated based on traversed AS numbers. The=20
> > prefixes in the same AS almost have the same AS_PATH=20
> associated, and=20
> > aggregating prefixes according to AS will shrink BGP routing table=20
> > significantly. I don't know what comments the ISPs make on=20
> this kind=20
> > of routing scheme.
> >
> >
> > -yang
>=20
>=20
>=20
