[rescue] Re: misc old Sun resources / now dry pair

[James Lockwood]

On Tue, 23 Jul 2002, Leslie Connally wrote:

> I have long talked about this generally to several people, but never
> understood the 'boxes' at each end of the drypair ( do you need one or two
> pair?).

It depends on what protocol you are running on the line.  If you're using
HDSL, you'd use 2 pairs like a DS1 and you have DS1 issues (separate
transmit and receive lines if at all possible).  SDSL takes a single pair.
HDSL-2 uses a single pair and OPTIS modulation (16 PAM, trellis coding and
spectral shaping) instead of 2B1Q.

There are many manufacturers of these boxes.  Pairgain was a common one
(they merged with some TLA recently, I don't remember which).  They
usually take either v.35 or ethernet in.

I just reread your question.  I was referring to wire pairs.  You only
need a single pair (which may not be identical) of modems/bridges/routers,
one for each end of the cable.  Slower ones (384-768kbps) are becoming
extremely cheap on the used market.

-James