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To: cs551@merlot.usc.edu
Subject: Re: lecture 21 slide no 27 
Date: Thu, 03 May 2007 22:34:23 -0700
From: william@bourbon.usc.edu

Someone wrote:

  > In the graph shown in slide everything seems to be perfectly fine
  > for flow A. How ever as the token bucket takes 1 sec to fill up
  > for the flow B we see a lower bandwidth than 1 innitially.
  > 
  > Now  I have a doubt here . Shoudnt the step up in the graph start
  > from 1sec instead of starting from 2 sec for flow B??Is it since
  > u are imagining your simulation to start from 1sec??
  > 
  > Also as the tocken bucket doesnt allow packet to flow until
  > enough packets accumulate Shoudnt the flow lines A and B start
  > from a 0 value and immediately jump to the desired value???

You should think of the drawing as a snapshot of something
that has been running for a while.  There is no simulation
going on here.  It's just a drawing to illustrate an idea.
(I drew the picture myself and didn't try to match anything.)

The idea here is that flow B can sustain a burst while flow A
cannot.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>