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Train wreck (was "Does TCP Need an Overhaul?")

  • From: Fred Baker
  • Date: Mon Apr 07 12:38:08 2008
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On Apr 7, 2008, at 8:36 AM, Lucy Lynch wrote:
Anyone out there attend this event?

The Future of TCP: Train-wreck or Evolution?
http://yuba.stanford.edu/trainwreck/agenda.html

how did the demos go?

The researchers demonstrated four things that made sense to me:

(1) TCP is not the right transport for carrying video data if what you want is real-time delivery. Carrying stored video (YouTube-style) is fine, but if you're trying to watch TV, you really should be using some other transport such as RTP or DCCP. Same comment holds for sensor traffic, but the astronomers who carry radiotelescope data halfway around the world weren't present.

(2) TCP is probably not the right protocol for carrying transaction traffic within a data center. One speculates that SCTP (which has a concept of a stream of TCP-like "transactions" that can be handled out of order and allows for congestion management both within and among transactions) might be a better protocol, and in any event that when thousands of transactions back up in a gigabit Ethernet chip's queue on a host that the host should start noticing that they are experiencing congestion.

(3) 802.11 networks experience not only the traditional congestion experienced in wired networks, but channel access congestion (true of shared media in general) and radio interference. In such networks, it may be useful to think about congestion as happening "in a region" as opposed to "at a bottleneck".

(4) When it is pointed out that instead of complaining about TCP in cases where it is the wrong protocol it may be more useful to use the transport designed for the purpose, researchers who presumably are expert on matters in the transport layer respond in complete surprise.
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