DSL factoids

[Aaron]

For those of you who care, here's how it works...  This is specific to ADSL, SDSL
works kind of the same way but not exactly, AND, this is just a quick rundown of the
Kansas City area...

Packets flow from your house via your phone lines (the same phone lines you talk on,
just a different frequency) to the Central Office of Southwestern Bell (the CO).
There is basically a large ring strung between the central offices (last time I
checked this was a DS3 (45MB), but could have been upgraded by now) that links all
of them together.  Your ISP then buys bandwidth from SWB (normally another DS3)
specifically to carry DSL traffic, which is plugged into a router at thier location.

Dave Parker wrote:

> I'll check with my ISP on this.  I don't think they have any equipment
> in
> the CO at all.  I may have misunderstood, but I thought I understood
> them
> to say that it was just a straight through connection, that the wire
> went
> from my place to the CO where it mated up with another pair of wires
> that
> went to their place, with no intervening equipment, just a connection.
>
> What might be interesting to find out is what someone like ADT has to
> say.
> Or any alarm/security company, for that matter.  Just call them up, tell
> them you're interested in a home security system, and you'd like to know
> if they've had any trouble getting wire pairs to use in your area.
>
> But it just NOW hit me why we may be having a difference of opinion here
> (assuming we're really having one - it seems pretty small to me if there
> is one at all) - people keep bringing up T1s and T3s, but in my case
> they
> don't enter the picture until my connection gets to my ISP.  I believe
> that it only uses the CO as a location to join two wire pairs together
> to
> create one wire pair path to my ISP, and it's at my ISP where bandwidth
> becomes a factor.  My wire path to my ISP carries ONLY my traffic, so
> I've
> got all the bandwidth I need to get traffic back and forth from my ISP
> and
> me.  Distance is a factor, yes, but the combined distance from my place
> to
> the CO to my ISP is considerably less than 18,000 feet, so distance is
> not
> an issue, and the connection from my place to the ISP via the CO has
> been
> tested and found to be clean and free of taps and coils, and I'm
> getting
> throughput at close to the theoretical max whenever I've actually
> noticed.
> Mostly I just notice 'FAST'.
>
> Walter Dunz wrote:
> >
> > The condition of the line is only a small factor in providing DSL service.
> >
> > First and foremost, you must be within approximately 18,000 feet of the
> > switch.  This is linear wire length, not geography, as the quality of the
> > signal falls off the further you get from the tranmitter.  You could be
> > located 200 yards from the CO, but if they have to run cable 2 miles up and 2
> > miles back to cross the river that is in between, you will be limited to 56k
> > for a while longer.
> >
> > Only about 45% of the current phone customers actually are eligible for DSL at
> > this time.  (SWB and the press will tell you this number is a lit higher, but
> > they have been guilty of telling tall tales before!)
> >
> > Next, if you are using a provider other than SWB, then SWB must have enough
> > room in the central office location to allow your provider to co-locate the
> > proper equipment.  This is a judgement call for SWB and guess what - they
> > often feel there is not enough room in the Central Office facility.  (This is
> > the problem Birch is having here in KC, but recent court rulings have helped
> > to move things along a little bit.)
> >
> > For many of us over the 18k limit, there is NOTHING we can do now, but relief
> > may be on the way.  New DSL repeater technology has been released that will
> > bump the limit up several thousand feet, but this only covers an addition 10
> > to 15% of us and will take about a year to roll out to the general public.
> >
> > SWB can not force you to choose them as your ISP.  You can choose whom ever
> > you like, provided that ISP has the equipment in the Central Office to pick up
> > your data and route it to and from the ISP's location.  This is usually done
> > over T1's or T3's so you don't have to worry about the technology behind that
> > segment.
> --
> Dave Parker/DLP, Inc.    dlparker at dlpinc.com    www.dlpinc.com
>