Re: [PLUG] DSL: Questions to ask?

[gabriel rosenkoetter <gr@eclipsed.net>]

On Wed, Aug 08, 2001 at 07:00:57AM -0400, Arthur S. Alexion wrote:
> I've been considering a cable connection in my small office.  The cable 
> modem would be connected to a Linux machine, with 2 windows & 1 other 
> Linux machine accessing through that server.  Are you saying that cable 
> is not a good way to go with Linux? What are the problems?

Don't think I said that exactly.

I feel that cable modems are not a good way to go under any
circumstances. They are shared bandwidth right from the point of
access. All internet connections will eventually be forced through
a pipe somewhere that is, under peak usage situations, probably
smaller than the sum of all the theoretical speeds of the
connections running through it. But with cable, this happens right
at your wall. With other solutions (DSL, ISDN, leased line/frame
relay, fixed wireless) it happens upstream where there's an
"intelligent" router [1] conneting your copper (or whatever) line
into the fiber backbone. It takes a lot to slow this down. With
cable, on the other hand, you need to keep in mind that the claims
of 2 MBps transfer speeds apply only if no one else on your segment
is connected to the network at that time. In any urban environment,
the chances of having a whole cable link to yourself (we're not
talking "several houses" or "block" here; we're talking as many
connections as would go through the same CO under DSL, which has a
radius of about 18,000 feet) is pretty unlikely. What's more, your
connection is slowed (and latent) to the immediately upstream hop,
rather than considerably later in the path.

With my fairly low-end DSL connection, I almost never see latency.
When I do, it's often because of the size of the touch point between
my ISP's upstream provider and the upstream provider of the site
to which I'm trying to connect. Perhaps the SpeakeasyNYC<->Alter.net<->
Yipes!<->Swarthmore (the connection I most frequently make) path
is just wider than your average path and I'm getting lucky, and I
haven't investigated who owns what caliber OC lines between me and
various important places, but the fact that my connection speed is
actually dependent on this backbone infrastructure further up rather
than on how many of my neighbors are downloading pr0n is kind of
nice.

Maybe you'll go with cable and maybe you'll be perfectly happy with
it. Having played with other people's connections of both cable
and DSL, it was clear to me which I wanted to have for myself. You
might want to try doing the same.

[1] In quotes because they aren't very. Yet. Go read Wired 9.05
for some interesting stuff on where switching is going. The short
version is that routing could be far more intelligent than it is.
Also on the horizon (maybe even mentioned in that same issue of
Wired, actually) is true optical switches. Not the kind that Cisco
wants to sell you, which are optical in that they have fiber
connections inside but NOT in that they never transfer light
signals to electrical signals, which is the only real way to see
the tremendous speed boost over existing switches that optical
switching will provide.

-- 
       ~ g r @ eclipsed.net


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