>> Thank you for contacting the Online Technical Support group.
>> There can be a number of factors that influence a cable modems speed,
>> some of which are:
>> - As the number of cable modem users increase at any given time,
>> everyone's download speeds drop, as the cable line is a shared medium.
>True, but a 1 million people shouldn't be put on one line.
in my experience, the number of people on a "single line" (as you put it)
with cable in the most highly penetrated areas is about 500HH per node *
about 20% penetration = 100 HH; most MSOs at that point would allocate 2
full 6MHz channels for downstream, but suppose not - a single 6 MHz
channels has a capacity of about 40 Mbps, so that means an average
throughput of about 400 kbps per HH, assuming everybody downloads or
streams at the same time. More reasonable assumptions are max 50% users
logged in at peak time, and only streaming or downloading no more than 50%
of the time, so about 1,600 kbps - hence the typical approach to
engineering of the cable modem network suggests there is no problem there.
Places where there is a problem are nodes that are much heavier in HH (very
old networks, they are typically being eliminated, but it takes a bit of
time), or places where users have unconstrained (non DOCSIS) modems and use
them for banks of applications (garage ISPs...), or places where
penetration is much. much higher (few such places still)...
When penetration grows, the solution is to "split the node", i.e. move from
1 500 HH node to 2 250 HH nodes, 4 125 HH nodes; also, go from one 6MHz
channel to 2 or more; it is not a very complex or expensive process, simply
takes a bit of time and MSOs have been busy with turning networks on first.
Note that DSL is also a shared medium, typically using ratios of 10 to 1
all the way to 25 to 1 (some even more) for the multiplexing beyond the
Local Office... do the math, you'll see it does not compare favorably once
penetration arrives at about 20%...
Critiscism is easy... cut these guys some slack, they work hard at making
the product available broadly and at a very competitive value...