[lug] DSL in Denver?

[Nate Duehr]

On Thu, Jan 27, 2000 at 09:28:06AM -0700, Viggy wrote:
> Are you in an apartment?  Is this a fairly new housing complex?  There
> are a couple of reasons why you cannot get DSL (or ADSL):
> 
> 1)  You have to be within 15,000 feet of the CO (phone switch).  This is
> 15,000 feet of wire, not 15,000 driving, or line of sight.
> 2)  Some of the "older" new housing complexes was wired with fiber
> optical cable to support all of the houses, and any "upgrades" (i.e. a
> resident orders two more phone lines, etc.).  Fiber is not compatible
> with ADSL.
> 3)  If this is an apartment complex, and old enough, the phone lines
> might be multiplexed.  In other words, USWest puts more than one phone
> number on a physical pair that leads into the apartment building.  ADSL
> is not compatible with this setup.

There's some truth to this and some half-truths.

For #1: Not true with some flavors of RADSL and SDSL.  Limits have been
pushed further than 15,000 feet.  Usually the available speed drops the
further you get from the head-end equipment.

USWest is sticking with the lower numbers for standardization and since
they have a huge investment in the equipment they originally went with.
Some of the competitors like Rhythms, JATO, FlowPoint, and Covad have better
equipment and if they have a POP (point-of-presence) in the Central Office
that services your area, you can usually get service further out than USWest
offers.

Example: USWest says I'm not in service coverage.  My Rhythms connection
was expected to run about 512K max (RADSL), and actually tested to a max
speed of 784 symmetric (same up as down) during the installation.  (And
hoo boy, I tell ya, I was SORELY tempted to put in the order to just
LEAVE it that fast after seeing that here at home... whew!)

For #2: Also true to a point.  Fiber is typically used to feed systems
that use "concentration" and are designed for voice service like GR-303
equipment and SLC-96 compatible channel banks.  These play hell with
standard analog modems, and because you don't have copper all the way to
the CO, DSL cannot ride out to you.  HOWEVER, if the telco has a powered
vault or other powered location with enough copper in a particular
subdivision or (better yet) apartment/condo complex, they will typically
install a head-end DSL box at the "end" of the fiber (most fiber is laid
out in ring topology if it's SONET... doesn't have to be, but usually
is...) and can service the neighborhood that way.  So it's usually a
number-crunching/bean-counting exercise for the telco.  If they can
recoup the cost of the extra equipment and LOTS of people in a
particular area have shown an interest in DSL service, they *can* do it,
it's just a matter of time and money.

For #3: It's just an extension of the engineering dilemma the voice
telco's put themselves in in #1.  Technologies like GR-303 and SLC-96
allow a telco to have a much better use of their facilities with less
copper in the ground, but they didn't anticipate someone coming up with
a way to do broadband over copper (while still using that same pair for
dial-tone voice) ten years ago.


-- 
Nate Duehr <nate at natetech.com>

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