High Speed Internet Providers

[richb at pioneer.ci.net (Rich Braun)]

Kelly Brown wrote:
> The problem with cable is that you share the cable to the concentrator.  As
> more folks subscribe in your neighborhood, and during peak times (esp. with
> pay-per-view) the available bandwidth to you will drop.

That's not where the problem is; there is far more capacity on each segment
than required.  The problem with my own cable-modem service is the lack
of monitoring.  By contrast to ISP companies which built themselves from
the ground up with monitoring capability on every 24x7 circuit, the cable
companies seem to basically have no idea where the bottlenecks in their
networks are.

AT&T developed a specification which is actually fairly sound.  A cable
segment "passes" 420 households, delivering 40 megabits of capacity in the
downstream direction.  I've forgotten what the upstream capacity is, but
it's also fairly high.  It's *not* like an Ethernet; the upstream and
downstream channels are on different channels entirely.  Allocation of
bandwidth across subscribers works more like a token ring than an Ethernet,
but it's a whole new design.  Look for 'docsis' on your local search
engine to read more about this.

Hence if every one of your neighbors were:  (a) subscribing to the cable-
modem service, and (b) downloading from the net simultaneously, you would
still be getting about 100 kilobits of downstream capacity.

Chances are, the entire cable connection to your town is a single
45-megabit DS3 connection or (even more likely at this stage of the
game) a handful of 1.5-megabit T1's.  At the head end beyond the cable
concentrator, it's the usual set of Cisco routers and so forth that
any ISP uses.  So the choke point is really at that point, not in your
neighborhood.  Service quality depends--like any ISP--on how well the
company monitors traffic on the various segments and on how well it provides
fault tolerant connectivity to handle the traffic.

-rich
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