North American Network Operators Group
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Re: Baltimore train tunnels (was Re: Vulnerbilities of Interconnection)

  • From: William B. Norton
  • Date: Sun Sep 08 19:35:41 2002 
At 09:47 PM 9/7/2002 -0400, Sean Donelan wrote:

Unlike phone calls, TCP traffic doesn't occur in fixed bandwidth
increments. TCP traffic, 90% of Internet traffic, is elastic. By design,
TCP adjusts the traffic rate to keep the bottleneck congested.  As the
bottleneck moves, traffic reacts by increasing or decreasing the rate to
match the available capacity.  This feedback occurs independently of what
is happening on nearby traffic paths.  Even if there is available
capacity on elsewhere, the current Internet design is not very good at
using it.  Some people view this as an inefficient use of available
capacity, other people view it as a self-protective mechanism.
Thank Goodness for well-behaved applications, right? ( Misbehaving TCP stacks and UDP-based apps don't obey these back off rules. ) I remember Van Jacobson gave a presentation back in 1997 that spoke about the problems with applications that didn't exhibit these characteristics: http://www.academ.com/nanog/october1997/

It would be interesting to see some recent verification that well-behaved TCP-apps are the norm on the Internet...any data out there in this regard?

Bill