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| Cable-do - the Ancient Japanese Art of Network Wiring |
(or, the adventures of Robert, amateur network designer)
Wherein our hero pluckily upgrades from Localtalk to a mixed Localtalk/Ethernet network,
Experiences many hazards and adventures, and
Devises ingenious solutions to annoying problems.
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| What has gone before: |
[Top] |
While the AnimEigo office had been running quite happily on poky old Localtalk
for many years, with the advent of the in-office webserver, it became clear that
a mass migration to the promised land of Ethernet was long overdue.
Compounding this desire in the heart of our protagonist was the desire to banish
from his sight the ugly pairs of localtalk cabling descending like venomous vines from
the ceiling tiles near each workstation, the legacy of a two-bit cabling job foisted on
an unsuspecting office by heathen minions of the Wintel alliance whilst our hero was
off battling the demons of licensing in far Nippon.
Something had to be done. Our plucky neophyte network designer plunged into the
catalogs in search of enlightment, if possible, but in any case a decent price on
an ethernet hub. And therein was planted in the fertile field of his malleable mental
mushroom the seeds of the PLAN.
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Like the best laid plans of pointing devices and men, the plan was simplicity in
itself; replace the current telephone wall plates with new plates that could accommodate
4 jacks. One would be the existing telephone jack; the other three could be dedicated
to network purposes. Thus, the plan could be divided into the following tasks:
- Running the cable from a central wiring room to the wall plates.
- Assembling the jacks (aka punchdown).
- Interconnection at the wiring room.
Complicating the plan was a desire to create an passive Localtalk star, so that the
aforementioned ugly cables could be ceremoniously ripped off the walls. The cunning
cabler concocted a sneaky plan to implement this. Reasoning that ethernet cable contains
8 wires (only four of which were actually used, probably because the cable manufacturers
bribed the ISO standards organization), and localtalk cable contains 4 wires (only two
of which are used; hmm... a pattern?), our hero dredged from the depths of dim memory
the secret of division he had learned as a wee lad in bonny old England, and came to
the stunning realization that an ethernet cable was in fact equivalent to two localtalk
cables; and that furthermore, one ethernet cable could thus
carry the localtalk signal out from the central
wiring room and back again! If this were so, then if, and only if, the cables were
properly interconnected in the central wiring room, and if, and only if, there was either a
phonenet connector connected to the jack in each room (or a special "loop-back" plug), then
a complete linear (if somewhat topologically twisted) localtalk network would thus be
created.
It was cute.
It was elegant.
It probably wouldn't work.
Therefore, it had to be tried!
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| Thus it came to pass... |
[Top] |
that one weekend, ably assisted by Marc, the only other guy in the office (the women
being far too intelligent to blow their weekend shoving cable along the ceiling), your
intrepid reporter cabled his domain for ethernet. In the process, much fun was had, much
sweat was dripped, several knuckles were skinned, and some wisdom was gained. And the rest of this
web-page, following as it does this over-long and over-cute introduction, contains that wisdom.
Enjoy!
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Cable tips
Remember to get PLENUM CAT-5 cable. A bit more expensive but better for you. Also take the
time to connect all 8 wires. If you do, you can upgrade to 100-base-T without messing with the
wiring!
We ran three new cables to each wall plate, so we ordered our cable on three reels. We marked
each reel with a color, and wrote that color on the end of each cable we pulled. Then after we'd
pulled the cable, but before we cut them at the cable room, we again marked the other ends. That
way it was easy to see what cable was what.
Always give yourself 2 feet more slack on either end than you think you need.
When running multiple cables, tape all but one of them together, then tape the last one to
the first bunch so that it sticks out an extra few inches. Add some tape so that the transition
between the big bunch and the "leader" cable is smooth. This will make it easier to thread.
Getting cable threaded over a suspended ceiling
In our office, the problem was that we had a suspended ceiling with all of the current phone
wires running over the ceiling and then down through a hole in the top of the wall to the wall
plate. Thus, we needed to get cable from the central wiring room to the individual rooms, and
we wanted to it without taking down a lot of ceiling tiles. The cute solution was to take some
string and attach it to a rubber band, and use the rubber band to shoot the string from the
central room to wherever we wanted it. We could then use the string to pull the cable.
We never ran cable diagonally across the ceiling, because we wanted to avoid the flourescent
lights (noise!). So we stapled down some big cheap cable ties at places where the cable had to
change direction and used them to hold the cable in place.
Getting it down through the walls to the wall-plate.
First, you have to hope that there is a clear path from the top of the wall to the little
box behind the plate. Usually there will be on interior walls. Drill a hole (it won't be pretty)
in the top of the box for the new cables. Don't use the existing hole into the box, because it
will be tough to thread into. If you can, you can use the existing hole in the joist where the
original phone-wire goes down. Otherwise drill another. If you drill, measure carefully and
drill so that the hole is right above the hole you made in the box.
Now make your hook. This is a string with a small nut and bolt on the end. Then straighten a
paper-clip and make two tiny loops in it, and thread it along the string so it is just behind the
nut+bolt. Gently helically twist it around a pencil (1 turn max) to give it some "body". Now drop
it down the hole in the joist until it is just above the box (you can often hear it clink, and I
made a knot in mine to mark the right distance).
If you are good, you can drop the hook right into the box. If you are like me, or if you have
to offset the hole, you will need to get a flexible magnetic grabber ($5-10 at an auto-parts
store) and go fishing for the hook. It really works like a charm.
Use the line to pull the cable into the box. Give yourself more slack than you think you need.
Punchdown tips
Punchdown is what you do to connect all the little wires to all the little jacks. You use this
cool Impact Tool to insert the wires into the jack. Just match up the colors. Be careful. Look
twice. Make sure you tightly hold the jack and punch straight down, or you can break the jack.
There are several equally good wiring standards to use for wiring. The jacks will be colorcoded
for one standard (probably T568B). Make sure all the jacks use the same standard, and make all
your plugs the right way.
Plug tips
Basically, you have to spread out all the wires, insert them into the plug, and crimp. Here are
a few tips.
Untwist one pair of twisted wires at a time, then hold them between thumb and forefinger (the finger
next to the thumb, right?) and
stroke out, bending the wires as you go. Do this a few times and you'll get the wiggles out of
the wire.
Once you have all the wires in the correct layout, repeat the above process with the whole set
to get them ready for crimping.
Cut off any excess wire with the cutter on the crimping tool. You need to get the wires to be
the right length and even. I found that if I held the wires with thumb and forefinger with the
forefinger against the stripped insulation, if I then inserted the wires in the cutter as far as
I could before the crimper body hit my forefinger, it would be just right to cut.
Insert the wires in the plug. Check twice they are correct. Push them in hard. Make sure
you can see all the ends at the front of the plug. Push some of the insulation up and into the
plug if you can. Then crimp.
forefinger.
Wiring a Passive Localtalk Star
Phone plugs accept four wires, or two pairs. Localtalk uses the outer pair of wires. So first
divide the four-pair ethernet cable into two pairs of pairs. In my case, I used Brown-Blue, and
Green-Orange. Each pair will have a solid colored wire and a white-solid colored wire, of course.
For each room, you need to wire either a RJ45 (ethernet, 4 pair) plug to RJ11 (phone, 2 pair) x 2
patch cable. The RJ45 end plugs into the wall plate. The two RJ11s plug into your phone-net box.
The RJ45 end is standard, just like all your other RJ45 plugs. The two RJ11s wire like this:
| Pin | RJ11 #1 | RJ11 #2 |
| 1 | White-Orange | White-Blue |
| 2 | Green | Brown |
| 3 | White-Green | White-Brown |
| 4 | Orange | Blue |
To create a loopback plug for those rooms where you don't currently use localtalk, get four
strands of wire, straighten them, fold into a U-shape, and insert into the RJ45 plug as follows:
| Wire # | From Pin | To Pin |
| Wire 1 | 1 | 5 |
| Wire 2 | 2 | 4 |
| Wire 3 | 3 | 7 |
| Wire 4 | 6 | 8 |
This works for T568B wiring, I dunno if it also works for T568A. Draw a diagram and you'll see
how it works more clearly. I found that putting an inch-long snippet of cable sheath back over the
wires and into the plug before crimping makes things work better.
The central wiring room connection is done on a standard telephone punchdown block. This has
50 rows of 4 terminals each. The left two terminals in each row are connected to each other, as
are the right two terminals. You can connect the left and right sides with bridging clips.
Take the cable from the first wall plate and punch it down onto terminals on the left side
starting at the very top. Punch down as follows: Brown, Brown-White, Blue, Blue-White, Green,
Green-White, Orange, Orange-White. Now take the second cable and punch it down on the
right side, starting at the 4th position down: Green,
Green-White, Orange, Orange-White, Brown, Brown-White, Blue, Blue-White. Note that this makes the
Green and Orange pairs from first cable match with the second cable!
Repeat the process, punching down on the left and right sides, always punching down wires that
match the wire on the other side of the row. Then insert bridging clips between all of the rows
(after continuity testing using a ohm-meter and one of your loopback plugs, of course!).
Now just plug your patch cables or loopback plugs into the walls, make sure that the devices
on the ends of the network are connected to the correct half of the patch cable, and have a
termination resistor, and you're in business. If you are very sneaky, you could even wire the
termination resistor into the punchdown block. I didn't get that fancy.
Further Resources
I got all my cable and parts from Milestek. Their
prices are excellent, and the sales-reps know their stuff.
Call them at 1-800-524-7444 and get their catalog, it is full of helpful tips.
Mike and Anne have some wonderfully detailed
tips on structured cabling which
are a must read. Wish I'd found them before I started!
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