[thelist] cable modem bandwidth

Daniel J. Cody djc at five2one.org
Tue Sep 12 13:16:32 CDT 2000

Part of the idea that cable modems will get slower with more and more
people in the 'hood using them is true, part isn't.

Back around 4-6 years ago, when cable modems first started becomming a
bit more mainstream, one of the big knocks against them - as the SWBell
commercial points out - is that the more people in your neighborhood
that used them, the slower overall they got.

Typically this was true because the infrastructure that the cable
companies were using to deliver intenet access was(and still is in many
areas) very outdated. Most of the infrastructure(the physical wires,
cables, switches, etc) in place when the cable modem explosion hit 4-6
years ago was equipment that had been deployed in the early-mid 80's
when the cable tv boon hit. Cable companies tried to push too much data
across this somewhat primitive infrastructure, and the result was poor
service and slow download times as the number of people using it

So that explains part of the perception that cable modems are slow(we'll
get to more in a bit). DSL on the otherhand uses plain old telephone
wires(more or less for the sake of this discussion :) to give you
service to your ISP. Here is my big thing with DSL: They'll promise you
'Near t-1 speed to the ISP!!' and that is right on the money. You will
always have that near t-1 speed to your ISP no matter how many of your
neighbors get the service and download pr0n mpegs.. They'll get t-1
speeds to the ISP as well. It sounds great untill you've got 50
people(on the low end) with DSL at 'near t-1 speeds' connecting to an
ISP that only has one t-1 to the internet to start with.

So while you're getting t-1 speed from your computer to the ISP you get
DSL from, you only can connect/download as fast as the highest amount of
bandwidth your ISP has. If your ISP has a t-1 line, the maximum you can
download at is t-1 speed(around 1.5Mps). Now if your neighbor next door,
or even a person on the other side of town, also has DSL and is trying
to download at the same time you are from the same ISP, you're going to
have to share bandwidth. Not bandwidth between you or them and the ISP,
but between the ISP and the internet.

Now, most any decent DSL ISP would have more than a t-1 connection of
course. But even with a pretty large t-3 connection(45Mps) to the
internet, it can get crowded (and slow!) in a hurry.

So the real question is, "Whats worse?" Sharing bandwith between you and
the ISP(cable modems), or sharing it from the ISP to the internet(DSL
connections)? Naturally, the less you have to share is better, which is
why DSL providers have enjoyed a lot of success in the last 2 years -
they've capitalized on the mistakes that cable companies were making,
and the slow speeds that typically provided.

Now, this brings us back to the whole infrastructure issue. The cable
companies aren't stupid. They've been seeing cable modem users move to
DSL because of some of the slowness issues. They've also seen eroding
market share in the TV space because people are/were moving to
satellitte's(sp?) for digital TV. So they've responded over the last 1.5
years by spending a shitload of money on their infrastrucutre to kill
two birds with one stone.

Time Warner cable for one(and I won't even go into the possibilites of
their merger with AOL for the sake of message length :) has been out
there like a banshee laying down high speed networks to pump both
digital quality TV and internet access to the home. Here in Wisconsin is
a good example of what they're doing nationwide: Laying down the biggest
fatest pipes between their offices and the homes to pump as many
services as they can to you. They've been putting down fiber optic
ATM(asynchronis transer mode) networks(oshkosh, where i live is a great
example of this) for the last 2 years in order to get all these services
to the home user.

These ATM networks are capable of 155Mps(and will have the power to
scale higher with better compression technology) and towns are split
into nodes of seperate 155Mps networks. Milwaukee for example, has about
50 of these nodes that lay independant of eachother.(Joe across town
downloading porn wont affect your speed. your immediate neighbors will
though). These networks then all converge to a central point where it
connects to the internet.(this would typically be considered the ISP for
a dsl customer). Again, in Oshkosh and Milwaukee for example, they have
massive bandwith to the internet. I've been told they have between an
OC-12(622Mps) and OC-48(2.5Gps - giga) connection in areas like

So to sum up this rather long winded email ;)

Yes, cable modems are affected by your neighbors. So are DSL customers.
In the future, its all going to be about who has the most bandwidth and
best infrastructure to offer its customers. DSL is stuck using
POTS(plain old telephone system), which as regular modems have proved
over the last 15 years, can only be streched so far. The cable companies
like AOL/Time Warner are in much better position IMHO to provide quality
service to their customers in the future. 

Although you'll never really see breakneck speeds with a cable modem(or
DSL or analog modems) between 6pm and 10pm, it most definently is not a
passing fad - and IMHO, will be the one that wins in the end..

Again, sorry for the long assed email, just get off tangents sometimes
and can't stop :)


Jason Elliot Burk wrote:
> in reference to cable modems:  i've had a couple people ask me whether
> they should get them.
> now, i'm no guru, but i've always heard (i even have an .mpg of a
> southwestern bell commercial denouncing them) that cable modems will get
> slower and slower as more people get on the cable modem train...of
> course they're selling DSL service which isn't available in my friend's
> respective area just yet...but the question remains:  are cable modems
> here to stay or is it a passing fad?

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