Re: Asymmetrical routing opinions/debate

["William Herrin" <herrin-nanog () dirtside com>]

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