"Christopher L. Morrow" <christopher.morrow@verizonbusiness.com> writes:
On Tue, 24 Jan 2006, Robert E.Seastrom wrote:
Glen Kent <glen.kent@gmail.com> writes:
For example, an ISP can learn two different equal cost routes to a foo.com server via two different autonomous domains. It can thus split different flows (based on src-dest IP, src-dest Port, TOS, etc) across these two paths.
Do operators currently do this?
Folks can send me replies offline in case this constitues a "trade secret"!
Works great with a flow-based router (or layer-three-switch-pronounced- 'crippled-router'). The downside, of course, is that you now have a flow-based router in your network, which has been shown to Not Work Well under other specified conditions (worm outbreaks come immediately to mind).
I could be mistaken, but this is also a feature in mbgp, effectively loadsharing across two external paths. I presume the paths would have to be completely equal all the way down to the router-id and (probably) age-of-route ...
He said "via two different autonomous domains", which I took to mean two upstreams... and my understanding is that (on ciscos anyway) you're talking per-packet, not per-flow load balancing. What happens when you intentionally bugger stuff up so that you are per-packet load balancing your outbound traffic between two diverse (ie, non-congruent-to-the-same-upstream-and-pop) paths is left as an exercise to the reader... but I don't think TCP is gonna like it. :) ---rob