travis kalanick wrote: > If uTorrent's UDP implementation results in a more aggressive TCP, there > is certainly the possibility that uTorrent could create massive FAIL on > the Internets. > > Anyone who's created/tuned a distributed-UDP-based-TCP-like protocol > (e.g. David Barrett, Matthew Kaufman, Alex Pankrotov) knows the delicate > nature of how distributed-TCP-in-UDP works, and how it can go very > haywire with just a couple of well-intentioned tweaks.
Hi, Back about 1998 a company I was working for used a UDP wrapper around TCP packets. Each UDP packet had a unique number in the header for a given message/file transfer and the TCP inside did as well. The client collected them, found which ones had been lost in transit and sent a "resend message" for just those packets. Worked very well in very high RTT latency connections, like satellite and cell phone. The latency we measured on, if I recall correctly, Dokomo got as high as 51 SECONDS! although it averaged about 3 to 4 seconds and satellites was about 2 seconds RTT. TCP would never work, but UDP did. All that was needed was for the client to order the packets correctly and ask for any missing ones. The back haul went from about 13% for TCP on low latency links to under 1% using UDP. Even on high latency links we never saw much over 1% back haul traffic. One of the fun things about it was that the whole message/file could only be collected at end points due to the various routes UDP took at that time. The company still exists. It's now called Venturi Wireless at http://www.venturiwireless.com/ Best, Allen There are only 11 types of people in the world; those who understand binary; those who don't; and those who could care less, they just want the g^&d$%^ computer to work! _______________________________________________ p2p-hackers mailing list [email protected] http://lists.zooko.com/mailman/listinfo/p2p-hackers
