RE: Quick circuit question.

Two observations concerning the quick circuit question.

First, yes, T3s are definitely full duplex in nature. The only time anything
common is used is when the same strand of fiber is used in a WDM mode, with one
lambda supporting the east-west direction, while another lambda supports the west-
east direction. But even here, there is no interaction taking place between the
two paths.

Secondly, if the line is suspected as being the cause of a problem, tests should
be performed in the absence of end user data, simply to eliminate the line or tag
it as the problem. Testing should take place using bit-error test sets that employ
quasi-random and other forms of continuous data streams, instead. In this manner
no questions can arise as to ack-nacks or circumstances surrounding download-
upload conflicts and windowing considerations.

Finally, "dsx" does not stand for full duplex, as someone mentioned. "FDX" stands
for full duplex. DSX-n is an abbreviation that stands for Digital Cross-Connect at
the n level, which should not to be confused with the electronic time-slot-
interchange kinds of disgital cross-connects, known also as DACSes, but rather the
physical patch panel type of cross-connects we're all familiar with.

A DSX-1 is a twisted pair demarcation point for a DS-1 or T1 line. A DSX-3 is a
digital cross-connect for a DS-3 or T3. Etc.


On Tue, 6 Jul 2004 13:21 , 'Williams, Jeff' <> sent:

You might find what you're looking for at

They're the result of the TTC/ WWG merger.


From: [','','','')">owner-] On Behalf Of

Scott Weeks
Sent: Tuesday, July 06, 2004 1:13 PM
Subject: Re: Quick circuit question.

: We have 1 DS-3, that if we get close to 45Mbps IN/OUT the
: direction will be completely unusable. We have another DS3, that we have
: seen doing 45Mbps IN, and 15Mbps Out at the same time. This is going to
: sound dumb, but is duplex a consideration with lines of these types? I
: thought you could do either 45Mbps in, 45Mbps out, or a mix of both, not
: 45Mbps In, and 45Mbps out at the same time (90mbps)..
: I couldn't find this exact info on the net anywhere.

Anyone happen to know of where TTC's online library went a few years ago
after they merged with someone? (I've forgotten whom) There was a great
deal on T1s, T3s, etc. I have hard copies at home, but it'd sure be nice to
get some online copies, if they still exist.


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Date: Tue, 6 Jul 2004 14:45:44 -0500
From: frank@dti...

Finally, "dsx" does not stand for full duplex, as someone

DSx = DS0/DS1/DS3 (using "x" as wildcard). Not to be confused
with uppercase "X".