🚀 go-pugleaf

[POSTED TO comp.dcom.modems.cable; PLEASE REPLY THERE]

In <3A7B7FD3.9ABE0395@ufl.edu>, "Randy S." <rswitt@ufl.edu> wrote:

>> So, a couple of kids on a "segment" using Napster for instance, downloading a few tunes
>> and at the same time other users gettting tunes from them, could really slow or "kill"
>> that whole segment for all that are on it.  Right?
>
>Well, let's see, I believe a cable segment supports 54 Mbps download and 20 Mbps upload
>typically (I believe that they can vary this by how many channels they dedicate to
>delivery, I think there is 27 Mpbs down and 10 Mbps up per channel) .  If a segment has say
>270 users on it (assuming a 100:1 oversubscription ratio that John used as typical for DSL
>earlier), each capped at 2 Mbps download, 384 Kbps upload (I think that's typical?) it
>would take 20,000 / 384 =  52 users uploading at maximum rate to saturate the upstream
>stream.  Of course since many other people are ALSO uploading at normal rates, the real
>number would be somewhat lower.  Realistically, I would say 25-35 people uploading
>aggressively would effectively "kill" the segment.  Does that sound right, John?

I think the number needed to "kill" the segment is typically much lower,
perhaps as few as 5-10 -- see my own analysis in
<news:%oXe6.200$Tf1.8852@typhoon.sonic.net>.

>The
>kicker here is that this would happen even if they were all just uploading files to others
>on the same segment!

True.

-- 
Best regards,
John Navas     <http://navasgrp.home.att.net/>
     CABLE MODEM/DSL GUIDE:  <http://Cable-DSL.home.att.net/>