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

Sat Jul 24 19:23:23 UTC 2004

> Forrest W. Christian wrote:
> 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. When qwest says "insert a
> loopback plug at the smartjack" or "unplug from the
> smartjack" or whatever, they mean this device.

Thanks for posting the photo. A few comments: This all-in-one unit is
mechanically different but electrically equivalent to the split
NIU/smartjack photos I posted before; the smartjack part which is the
lower part labeled "customer interface" is a dumb PCB no smarter than
the Hyperedge glorified patch panel I posted a photo of.

An interesting feature of this chassis is that the rightmost card (which
appears to be a full-height one) seems to be a channel bank. A channel
bank is an HDSL card same as the general-purpose NIU but also demuxes
the 24 TDM DS0s in that T1 and outputs them as individual phone lines,
which could be the purpose of these 50-pin Centronics connectors on the
smartjack part, on the right of the RJ-48 jacks.

> Qwest can loop or unloop and do other tests to
> this device.

Indeed. As I said earlier, the brain of the smartjack is the NIU card.

For antique equipment, here's an RJ48 T1 loopback plug:

     +---------+
+----+---------+----+
!  | | | | | | | |  !
!  | | | | | | | |  !
!  1 2 3 4 5 6 7 8  !
!  | |   | |        !
!  | |   | |        !
!  | |   | |        !
+--|-|---|-|--------+
   | |   | |
   +-)---+ |
     |     |
     +-----+

> 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.

All depending on the age and feature set of the NIU card.

> Older ones have RJ45's on the right side and the
> cards are thicker - a lot thicker.

Yes. As well as the photos I posted earlier, these are "half-height"
type 400 NIU cards. The older ones were twice as big due in part to the
size of then-manufactured large capacitors.

> 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).

In California my guess is that the current strategy is to leave the
existing dual-spans in place and deploy fiber, single-spans being for
residential use. At home I am 10kft from the CO and I get 3meg aDSL over
the good old pair.

Recently I had a customer order a frac-DS3 (12 mb/s) from Sprint; when
you do the math it's only 8 T1s, not that much after all and will easily
fit into the chassis you pictured. Instead of copper the LEC (SBC)
brought in a SONET OC-12 ring and extended the demarc in the customers
data room (including the optical platform, they spliced the fiber at the
MPOE), which is great if the customer wants to crank up the volume.

Michel.