Asymmetrical routing opinions/debate
William Herrin
herrin-nanog at dirtside.com
Mon Jan 14 15:58:42 UTC 2008
On Jan 14, 2008 10:30 AM, Drew Weaver <drew.weaver at 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 at dirtside.com bill at herrin.us
3005 Crane Dr. Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
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