2 vs 4 wire leased lines
Ron Holt
connection. Do I need an analog or digital line? If analog is
sufficient, do I need a 2 wire or 4 wire line? Are CSU/DSUs only needed
for analog lines? I'm sure these are very basic questions, but I've
not been able to find a FAQ and the people I've talked to at US West
didn't know what I was talking about. Any help would be appreciated.
Ron
--
Ron Holt <r...@infonaut.com>
RKPRKP
Holt) writes:
Not an expert either but do know the following:
A 56K line is a digital circuit. You will need a CSU/DSU to connect.
The type of DSU/CSU depends on whether you will be directly
connected with a point to point circuit or if you are getting a
"switched 56" line which requires a different type of unit. For
example, Northern Telecom makes a "Datapath" unit which provides
switched 56 services but different carriers provide different
interfaces for switched 56. I would suggest asking your internet
provider to help. If not, there IS someone at US West who knows what
you need. You may just need to escalate until you get someone who
can help. Hopefully, someone else will provide you with a more
precise solution but this may get you started.
Macy Hallock
Generally speaking, you will want a 56kps digital line, DDS-II or
equivalant local tariff. Ask if there's a cheaper tariff for
this service (oddly enough, there are often two tariff's for
digital service in many areas...)
Techincally, it is a 4 wire service. Generally speaking, the line
terminates on a RJ-48S jack, a specially wired 8 conductor jack
(only four are used).
You will require CSU/DSU's on each end. For 56kps service, the
typical interface presented to your equpment is V.35. (It is possible
to get a unit that will do synchronous RS-232, but that's not a
technically sound idea, RS-232 isn't made to do 56kps) Most people
terminate their internet lines into a stand alone router (we use
Livingston's and like them) There are a couple of V.35 interface
cards made for PC's, but use them only with great care.
CSU/DSU's are made by many companies, with prices from $300 to
$600. We use new Adtran and used ATT 2556 units. Be sure you
get the right V.35 cables for your CSU/DSU, there are several types.
Check with your internet provider for details on this, they
have to make similar arrangements on their end. Its important
that you work with them closely on this project.
--
Macy M. Hallock, Jr. N8OBG +1.216.723.3030 ma...@telemax.com ma...@fms.com
Telemax, Inc. - F M Systems, Inc. 152 Highland Drive Medina, OH 44256 USA
Jeffrey Rhodes
If US WEST offers ISDNservice at your sight, you may want to use 64kbps
data calls from a single twisted pair. You could connect to Internet
only when needed, it might be cheaper that way than with a leased line.
Also, the IBM WaveRunner for IBM compatible PCs supports V.120 at 64kbps
on a Data Over Speech Bearer Service (DOSBS). If you had one of these at
each end for the Internet pipe and the "voice call" were within a
US WEST metropolitan flat rate dialing plan, then you could have your
dedicated access up all the time for a flat monthly rate (~$60-70).
ISDN TAs are cheaper than CSU/DSUs. To answer your question, I think
2 wire analog would run an analog modem without a CSU/DSU. 4 wire
digital would run a modem thru a CSU/DSU and give better noise protection.
Opinions are my own which means they may vary with actual facts.
Jeffrey Rhodes at j...@creator.nwest.mccaw.com