North American Network Operators Group
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Re: Current street prices for US Internet Transit

  • From: Andre Oppermann
  • Date: Wed Aug 18 10:37:39 2004 
Deepak Jain wrote:
Have you tried running a single TCP stream over a 10 meg ethernet with a 5
megabit/s policer on the port? Do that, figure about what happens and
explain to the rest of the class why this single TCP stream cannot use all
of the 5 megabit/s itself.
That's entirely a different example. If we are talking about a stream that is _exactly 5Gb/s or _exactly_ 5mb/s, the policer won't be hit. In the example we are talking about below, an _approximately_ 5Gb/s stream on an _approximately_ full pipe the performance will be significantly better than you imply. And I have customers that do it pretty regularly (2 ~500Mb/s streams per GE port - telemetry data) on their equipment with very small buffers (3550s).
The required buffer size depends on the RTT of the TCP stream going over
it.  If you have the 3550 with small buffers and 5ms TCP RTT then everything
is well.  If you have the 3550 with small bufferns and 200ms TCP RTT you
will run into troubles.

--
Andre