[101618] in North American Network Operators' Group
Re: Asymmetrical routing opinions/debate
daemon@ATHENA.MIT.EDU (William Herrin)
Mon Jan 14 10:59:44 2008
Date: Mon, 14 Jan 2008 10:58:42 -0500
From: "William Herrin" <herrin-nanog@dirtside.com>
To: "Drew Weaver" <drew.weaver@thenap.com>
Cc: "nanog@merit.edu" <nanog@merit.edu>
In-Reply-To: <B7152C470C9BF3448ED33F16A75D81C14D261CAEA2@exchanga.thenap.com>
Errors-To: owner-nanog@merit.edu
On Jan 14, 2008 10:30 AM, Drew Weaver <drew.weaver@thenap.com> wrote:
> I haven't noticed too many instances of this causing huge performance problems,
> but I have noticed some, has anyone noticed any instances in the real world where this
> has actually caused performance gains over symmetrical routing?
Drew,
There are at least two common scenarios where intentional asymmetric
routing (aka traffic engineering) benefits the sender:
Scenario 1: InterNAP-like product where the outbound packet takes a
path optimized for conditions other than shortest AS path. Conditions
might include minimize packet loss or maximize throughput as
determined by ongoing communication with testpoints in that direction.
Scenario 2: Cost minimization for bulk transfer. If you operate a
large mailing list or a usenet server, you might arrange for traffic
from the server to prefer peers first and then your lowest-cost
transit provider.
Regards,
Bill Herrin
--
William D. Herrin herrin@dirtside.com bill@herrin.us
3005 Crane Dr. Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
