|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Traffic Engineering
Another flash from the past... In message <[email protected]>, "James R Grinter" writes: > > [email protected] (Avi Freedman) writes: > > [email protected] (Sean Doran) writes: > > > P.S.: Curtis Villamizar had another interesting approach > > > which involved pushing content far afield to > > > machines with the same transport-layer (IP) > > > addresses, relying upon closest-exit routing to > > > connect one to the topologically-closest replication > > > machine. Unfortunately, while this could be really > > This is a problem I've been musing over lately. The best way that I > can see is to return suitable DNS answers to people. This avoids the > route instability problems that Sean comments on, above: > > Client gets TCP session established. > > Routes change, their inbound route now reaches a different system > which clearly doesn't know about the connection and *boom* goes > the TCP session. > > Routes return to their previous situation but by this time it's too late. > > (Even worse is when the client connects *during* the route instability.) Maybe this is unique to Europe? We put the prefix inside an aggregate. If routes to our /13 and /14 aggregates outside of our network are sloshing around that much that different provider interconnects are used mid TCP connection (often enough that it matters) there is clearly a serious problem in the adjacent provider and I can't see how they can stay in business (here in the US anyway). If this does occur some time in the middle of the few second long transfer (10s of seconds for a large slow transfer) then the client gets a RST and has to click again. If this is persistent, then someone in the path has a very serious problem. The only real problem you can run into is if someone is boneheaded enough to misconfigure their routing to do per prefix load splitting across WAN links or worse yet across providers. Again, such people don't deserve to stay in business (since *all* TCP traffic from their network will suck), but they do exist. The common newbie mistake is to configure per prefix load split among two default routes. Westnet used to do this many years ago. Some small network in Florida did this more recently. Curtis
|