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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Split flows across Domains
"Christopher L. Morrow" <[email protected]> writes: > On Tue, 24 Jan 2006, Robert E.Seastrom wrote: > >> >> >> Glen Kent <[email protected]> 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
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