Video: Jim Gettys on #Bufferbloat @googletalks #Internet

A Google Tech Talk from April 26, 2011 from Jim Gettys of Bell Labs. Jim is well-known as one of the original developers of the X Window System, and has long been active in open source and internet standards. His recent experiences with immersive telepresence applications exposed systemic implementation errors in many Internet buffer and queue designs. He describes the journey of discovery in this talk.

VOIP and teleconferencing often perform much more poorly on today’s Internet than the Internet of a decade ago, despite great gains in bandwidth. Lots of fiber, cheap memory, smart hardware, variability of wireless thoughput, changes in web browser behaviour, changes in TCP implementations, and a focus on benchmarking Internet performance solely by bandwidth, and engineer’s natural reluctance to drop packets have conspired to encourage papering over problems by adding buffers; each of which may introduce latency when filled.

Buffering mistakes have been made in all technologies: operating systems, home routers both wired and wireless, broadband equipment, corporate networks, 3G networks and parts of the core Internet itself. The mistaken quest to never drop packets has destroyed interactivity under load, and often results in actual higher packet loss, as TCP’s congestion avoidance algorithms have been defeated by these buffers. The lessons of the “RED manifesto” of 1997 have been forgotten or never learned by a new generation of engineers.

Full solutions require careful queue management, and that management should be everywhere; we no longer have the luxury to think that this is a problem solely of Internet routers. I will describe some of the mitigations and solutions to this problem, and how you can at least make your home network and systems behave the way they should.

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