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Issues around Buffer Bloat - Jim Warner, UC Santa Cruz

  • Jim Warner noted that Jim Getty has been promoting the "buffer bloat" issue.
  • Jim Warner felt that the mailing lists and websites like fasterdata.es.net were telling people that bigger buffers aren't a problem.
  • Carla Hunt asked what the recommendation that the mailing lists and websites are suggesting?
  • Jim said that fasterdata.es.net recommended an outbound queue length of 1000 packets for 1G, and 10000 packets for 10G.

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  •  He felt that was far too much buffer at home.

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  •  Most of the buffers filling up are in the DSL boxes which are unchangeable.

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  •  He noted that the outbound traffic can be shaped so that DSL queueing doesn't happen.
  • Martin Swany felt that this was a TCP problem.
  • He felt it was misguided to screw with sending so that TCP doesn't get confused.
  • Jon said that TCP worked that way, and because of that, we can't ignore it.
  • Jon thought the problem with buffering was that it was dependent on the link speed the router was attached to.

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  •  One megabyte of buffering was nothing for 1G ethernet, but on DSL, it's forever.

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  •  Jim noted that the effect of all this "hidden buffering" was a large percentage of a second (1/3 and higher).

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  •  Prasad noted that it can be even worse on a noisy channels like wireless where retransmits happen after 60ms so you can get even higher blocking times.

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  •  Jim said that wireless was a problem for lots of reasons, including that valid wireless speeds varied from 2Mbps to 100Mbps.

AGENDA AND ABSTRACTS

Fiber Asset Management Software -- Carla Hunt, MCNC

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