nanog mailing list archives

Re: T1 short-haul vs. long-haul - jack terminology


From: "Forrest W. Christian" <fwc () mt net>
Date: Fri, 23 Jul 2004 23:52:35 -0600 (MDT)


On Fri, 23 Jul 2004, Christopher Woodfield wrote:

OK, from my reading in Newton's Telecom Dictionary, it appears that NIU
is a generic term for "whatever the customer plugs their cable into",
be it a powered or a dumb device. Mea culpa.
...
"...installed on the premises as a semi-intelligent demarcation
point,
the smart jack is completely passive until activated remotely by a
digital code, typically something like 'FACILITY 2', sent down the T-1.
This code activates a relay [that loops the circuit]."

That may not accurately define the Adtran and Westell devices that are
pictured (they appear to have additional features beyond this), but
it's a good guess they provide the remote loopback function described
above in addition to the monitor points and management console port. I
also doubt that the Hyperedge unit pictured does so, although I can't
seem to find any online documentation on the unit  (it is, as you
described it, a 'glorified patch panel'). Feel free to correct me.

In Qwest land, NIU, Smart Jack, and Demarc (unless "extended") are all in
the same physical rack.

When you get a T1, qwest installs an appropriately sized shelf.  This
shelf holds the adtran and westell devices shown in earlier posts.  For
example, we have one site with quite a few T1's, which they installed a
rack like the one pictured at:

  http://www.westell.com/images/osp/dsawm214.jpg

Note the RJ45's on the bottom.  These are the demarc point for the
circuit.  Older ones have RJ45's on the right side and the cards are
thicker - a lot thicker.

When qwest says "insert a loopback plug at the smartjack" or "unplug from
the smartjack" or whatever, they mean this device.

Qwest can loop or unloop and do other tests to this device.  On the newer
HDSL cards, they can also plug a laptop in to get performance data, and I
believe they can also get this data from the CO end.

Also of note, I haven't seen qwest deploy anything but HDSL2 cards for
quite a while.   This basically means a full duplex, full-speed T1 over a
single pair of copper with a quarter of the repeaters (12K wire feet
without a repeater).

 -forrest


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