DSX cross-connect solution
Barton F Bruce
barton at gnaps.com
Mon May 4 19:25:17 CDT 2009
Use the ADC 84 port DSX blocks with six 32 pair CHAMP connectors on the
You will stay saner if use the ones with three sections - A B C - on the
front each with 1-14 jacks on the top row and 15-28 on the bottom.
The alternate that looks the same from a distance simply has a top row of
1-42 and the bottom row is 43-84.
We use and LIKE the ones that have 1/2 the wirewrap pins on the left and the
other half on the right - ON THE FRONT.
ADC has dropped hundreds of oddball custom DSX they used to make for every
primadonna boonies telco and have standardised on the higher volume items at
LOWER prices. Ten years ago, I could save a couple of hundred $s by ordering
a particular DSX pannel from North Supply and yet their price would suck
compared to Anixter's on some other panel and Alltel (now Windstream) would
beat them all on yet another one. It all boiled down to ITEM VOLUME PRICING
and not product family volume pricing from ADC. You had to use the supply
house that had LOTS of other customers that used the panel you wanted. The
plus there was that they would also be in stock and you didn't have to wait
a couple of weeks for the truck from Mexico to arrive.
In ALL cases, wire the 5th green "TL" (tag light) wire when you
crossconnect, and so when you jack intio the monitor port, you are also
grounding the TL wire and the tag led at each end of the xconnect flashes
for the 1st minute and then stays solidly on.
Use REAL ADC xconnect wire - two pairs and the green TL wire. It is TINNED,
and you really WANT tinned wire if you are wrapping.
Trivial to learn. Get any of several styles of cut-and-strip-to-wrap-length
tools and a good squeeze the long trigger bar manual wrap gun. Don't get an
manual twisty pencil size one - that is for the tech's emergency tool bag.
An electric wrap gun or even a pneumatic one is crazy for your volume. The
UNWRAP tool can be the manual pencil size one. ALL 5 wires can be stripped
DO NOT play with cut-strip-wrap bits - they are for assembly line work with
HIGH TORQUE tools and where incoming QA makes sure THE ONE WIRE TYPE being
used meets the special standards needed for such tools.
I LIKE single guage bits, but reality is that maybe 22-24 is good if you
have much 22GA ABAM you need to wrap, but more likely you want a 24-26ga
combo bit and can use it for everything else. Extra long bits and sleeves
may be a plus, too, depending on your panel. OK tool in NY makes all the
pieces you would need.
It is pure nonsense in a small shop where you are NOT feeding copper T1s out
to the boonies on your own cable plant to be even thinking of 22GA. In our
COLOs where the typical customers are all ISPs in racks less than 100 feet
away, we use a lot of 24GA and now 26GA cable and it is rats-ass Cat-3. NOT
ABAM, and there are no problems. We always will have O and I in seperate
cables, but that is more how panels come than necessity. The big EVIL ABAM
shields avoids is NEXT and there simply isn't any Near End Cross Talk when
everything is very close and all signal levels are about the same.
If there is any chance it will be wrapped ever, get TINNED cable. If I'm
ordering 28 pair cable with 32 pair connectors on both ends, I still get
tinned. It may be cut into two blunt tailed shorter cables that get that end
wrapped. It costs almost nothing more if your suppliers are well stocked and
typically are using the same cable for many other customers. DO NOT think of
wrapping cat-5! you will hate straightening out each wire so you can stick
it in the wrap bit. And you won't be able to strip more than one pair at a
time and even then you may want to do a wire at a time.
If I have 30 M13s per rack, the wad of cables going up to ladder rack
between racks is 60 cables. Using 26 ga, 28 or 32 pair TINNED but unshielded
cat-3 cable will make you very happy. If you are is a LARGE building even
way smaller than 111 8th ave, 26 ga is not for you. VZ uses 26 ga where they
can. for T1s too, but it is shielded.
You only have 300 T1s so you can stay reasonably sane no matter what you do,
but this is NOT the place to cheap out.
The ability to jack in and do testing or an end to end frontal patch in an
emergency is great.
Be absolutely POSITIVE you get the I and O connections done correctly and
your head and arms around the DSX terminology.
O is OUT - and that is NOT going away from you but is pissing bits at you
from the "TRANSMIT" side of whatever is connected there. O is what the
Monitor port is padded down from, also.
I is IN and where you stick bits IN towards whatever is connected beyond
that port and it would be "RECEIVE" in datacomm terminology at that device.
With 32 pair champ connectors on the back it is trivial to FIX if some tech
mixes things up on the back of the DSX (unlike when EVERYTHING was
wirewrapped), but just don't start letting the techs mess up.
If you do ONE wrong, cross connects to it will not work CROSSED, and so
techs wire them straight through, and now you have two M test ports looking
at the signal in one direction and NOTHING to monitor the other flow. M
should be looking at the signal COMING FROM that direction.
Get a couple crossed, and then any xconnects between those panels will need
to be Xconnected but M jacks are looking the WRONG direction, and it just
gets worse as time goes on...
NEVER let it start.
The ONLY X-connection is at the DSX panels t1 by t1 - O goes to the other's
I and I goes to the other's O. Again ONLY at DS-X does the "X" happen.
The 28 pair cable (32 pair connector) from the O port on an M13 simply goes
to the O port on its DSX panel, etc.
Beware the Telect panels that achieved high density by your needing their
blue SLIM plugs that cost more. and where each adjacent T1 was zigzagged
vertically from the adjacent ones to let them pack more densely. Fine if you
are buying used, but don't buy into the proprietary cord game - you don't
have any where near enough for it to matter. How many acres of lower
manhatten real estate must you save at any price? etc. ADC cords WILL work
but NOT if an adjacent T1 is patched. I think Telect dropped that game when
pissed off customers dropped them.
DAMN cisco. The PA-MC-2T3+ card, as over priced as it is, should have been
almost immediately upstaged by a PA-MC-OC3 card. PMC Sierra has had the
chips to do that "right" for ages now.
Each STS should then have been able to be optioned for M13 or VT1.5 format.
In M13 format, at least, each T2 (4 T1s or 96 DS0s) should have been easily
optioned to instead be 3 E1s - also 96 DS0s).
But the real real benefit here is not E1 support (which they DID DO WELL on
the OC3 european card) but would be having the 84 T1s be in VT1.5 mode so
all your DACSing could be done in a cerent (cisco 15454) chassis.
Even the old XC-VT cards did 336 T1s of any to any. That is 24 STSes max
each with 28 VT1.5 ports but when xconnected that makes 336 T1s
crossconnected as full bidirectional T1s.
And NOW the higher density XC-VXC-10G does 48 STSes of full bidirectional
T1s (ie 96 STSes can go to the VT1.5 capable subsystem on the XC card).
That card on EBAY the other day was BUY IT NOW for $2500 and the MAX price
seen was $4500 also a BIN price.
The EVIL game you want to avoid if at all possible is using cerent TRANSMUX
cards that go from M13 format to VT1.5 format. The original DS3XM-6 cards
ONLY connected the M13 side via electrical BNC or SMB etc jacks on the back,
but the newer DS3XM-12 cards finally delivered the "portless transmux" (no
BNCs needed) originally promised way way back.
The DS3XM-12 can on a port by port basis deliver the M13 side to either
external jacks OR internally via an STS logical crossconnect (ie PORTLESS
mode), The VT1.5 STSes are always done internally via the STS xconnect
Even used, transmux cards are rare and EXPENSIVE even by cisco's arrogant
But many of your interconnections to others can these days be ordered as
VT1.5s especially if you have an optical connection to them just as easily
as getting the growing old M13 format. Then do all crossconnecting from your
keyboard.. Copper DSX sucks. Real DACSes $$$SUCK$$$ too.
But back to elcheapo but sane copper crossconnect for T1s.
ADC bought the KRONE punch block line. Not only are these better blocks than
66 blocks, but they also can have jack in and look both way testing or just
jack in monitoring. They make various assemblies of these with 25 pair and
possibly 32 pair CHAMP jacks on the back, but I never saw one that fit the
"COLO-DSX" model where the normal through connection would be from one 32
pair CHAMP to another and there would be NO cross connections punched in
needed UNLESS you needed to break the "NORMALLED THROUGH" connection the
block provides. In that case you plug in an insulater or broken end of a
popsicle stick in an emergency, and simply punch in whatever crossconnects
you need. You would also need some custom cables to break the cross connect
for testing and these would end in a conventional but cord mounted pair of M
OI jacks (little 6 jack cluster) that would be themselves normalled
X-connect wise (O-I and I-O) but could then be accessed with the same test
cables used in a real DSX panel. I tried to "sell" one of their application
engineers on the idea that they should have built this, and he did me a good
mock-up drawing and then said he had discovered that Adtran had asked for
something similar (and without some of my enhancements) and THAT had been
turned by down product mgmt presumably because price or volume issues.
But rather than have a PREWIRED to a 32 pair CHAMPs backed Krone blocks,
just take 32 pair CHAMP ended cables to your M13s or whatever and punch the
tails of 28 pairs on one side of each Krone block. If you REALLY want to get
fancy, interleave O and I cables so an adjacent odd / even pair of pairs was
a T1. O cables go the ODD pairs, and I cables to EVEN numbered pairs. Then
x-connect from the other side as normal with a 2 pair jumper with the pairs
flopped at ONE end. No 5th green TL wire but at this low density, so what.
And you can make or have made frontal patch cables that override the punched
in jumpers just as you do with TRUE DSX panels. IE intrusive test without
breaking the punched in x-connect.
I'm amazed at how many folks that occasionally use Krone blocks do not know
those little slots are test access and even crossconnect capable mini jacks
that are normaled through when nothing is plugged in.
You can get bars that go across 19 or 23" racks that are designed to dense
mount 66 or Krone or similar blocks. Your own back room and NOT some ILEC
COLO? two strips of 5/8 prywood and you still leave open the center for
block assemblies that have side or rear CHAMP connectors, or even the 66
blocks with rear tywrap tails. Someone like Homaco or AllenTel may have just
what you want readybuilt.
----- Original Message -----
From: "Wallace Keith" <kwallace at pcconnection.com>
To: <nanog at nanog.org>
Sent: Monday, May 04, 2009 4:05 PM
Subject: RE: DSX cross-connect solution
*This message was transferred with a trial version of CommuniGate(r) Pro*
I would stick with wire wrap, 66 blocks make an inferior connection. If
someone cannot deal with wire wrapping, they are not living in a telecom
world. Find a contractor who can do this properly. Both Telect and ADC
have good DSX panels in varying densities.
From: sjk [mailto:sjk at sleepycatz.com]
Sent: Monday, May 04, 2009 3:56 PM
To: nanog at nanog.org
Subject: DSX cross-connect solution
I am trying to find hardware for a rebuild of our DS1 cross-connect
frame and can't seem to find much out there. We've got ~300 DS1s that
need to be x-connected between our M13s and I'm seeking an easy to
manage solution. I've looked at the Telect panels but I'm concerned that
my staff can't deal with wirewrap terminations. Has anyone seen, simply,
a high density 66 field that can fit in a 23" rack?
TIA -- steve
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