🚀 go-pugleaf

> | > >Conversely, since cable aggregates the
> | > >channels along each segment, it can overload the upstream channel even IF each
> | > >individual asymmetry ratio is not too high.
> | >
> | > The shared nature of cable is the killer because (1) the aggregate
> | > uplink capacity is typically much less then the aggregate downlink
> | > capacity [unlike DSL, where the aggregate is usually symmetrical] and
> | > (2) saturation of the shared uplink kills the downlink for everyone on
> | > the segment.
> |
> | Yes, this was the point you made that really caught my attention, and made LOTS of
> | sense.
> |
> | Randy S.
>
> 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?  The
kicker here is that this would happen even if they were all just uploading files to others
on the same segment!

Randy S.