Two reminders: (1) you gotta keep in mind where the bottlenecks are, and <br>(2) network usage is bursty. <br><br>So (1): TCP flows will achieve "min-max fair share" of the bandwidth, i.e. <br>they will saturate a link to the maximum capacity of the bottleneck between
<br> the source and the sink. Suppose you have:<br><br> ------------ D ------ F<br>A ---- B ---- C -----<<br> ------------ E<br><br>Suppose DF is the bottleneck, and AB has 6 Mb bandwidth. Flow A-F might
<br> consume somewhere between 0.5 DF to 1 DF on AB. The AE will have <br>plenty of bandwidth left over.<br><br>On (2): Suppose there is an AF flow, with the bottleneck link at AB@6Mb. The flow<br>will not be consuming bandwidth constantly - there will be bursts of activity.
<br>AIM may not have anything to send most of the time. When it does, it will <br>likely slow-start to bottleneck capacity pretty quickly. Another flow, say AE, <br>should get 5.9 Mb by bursting to 6 Mb when the link is free, and throttling to
<br>3Mb when there is competition. So achieving 5.9 depends on the "over time"<br>behavior of the protocol as opposed to how it shares the bandwidth "over space."<br><br>So that's two different scenarios where there would be unused capacity on the link.
<br>I think I summarized David's scenario accurately. <br> <br>Cheers,<br>Bob.<br><br><div><span class="gmail_quote">On 4/3/06, <b class="gmail_sendername">Matthew Kaufman</b> <<a href="mailto:matthew@matthew.at">matthew@matthew.at
</a>> wrote:</span><blockquote class="gmail_quote" style="margin-top: 0; margin-right: 0; margin-bottom: 0; margin-left: 0; margin-left: 0.80ex; border-left-color: #cccccc; border-left-width: 1px; border-left-style: solid; padding-left: 1ex">
David Barrett:<br>> Um... most connections aren't saturated 24x7. Like, I have a<br>> 6Mbps connection and sometimes I'm just using AIM. In this<br>> situation, I'd like to measure that 5.9Mbps is free.<br><br>
5.9Mbps is free to where?<br><br>I'll bet that 5.9 Mbps isn't even free to the first IP hop you see, much of<br>the time.<br><br>What really matters is how much bandwidth is available between you *and the<br>source or sink you are trying to communicate with*
<br><br>Matthew Kaufman<br><a href="mailto:matthew@matthew.at">matthew@matthew.at</a><br><a href="http://www.amicima.com">http://www.amicima.com</a><br><br>_______________________________________________<br>p2p-hackers mailing list
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