How to Wire Your Home for Ethernet
By Rick Rodman
Washington Apple Pi Journal, reprint
Huge numbers of iMacs, PowerBooks and G4s are being
purchased today as personal machines for the home.
Corporations may dictate platform uniformity, but when
people have a choice, they often choose Mac. And Macs, since
day one, have come with networking and sound built-in, not
just in a hardware sense, but well integrated into the
Networking a Mac can be as easy as plugging a "swapped"
cable into each machine's Ethernet port. By the way, we mean
a CAT-5 or CAT-3 Ethernet patch cord with swapped pairs. The
pairs are not assigned concentrically, but in a somewhat odd
fashion, so you can't use an inverting coupler; inverting
couplers and flat "silver-satin" wire is for ISDN and other
types of telephone use.
The next step is to get a small, inexpensive hub and
connect two or more machines, and maybe a printer, into the
hub. There's no configuration to do, just plug them in and
use it. Of course, the wires are a little messy, especially
when they go from room to room. Again, if your cables are
too short and you want to extend them, beware of the cheap
couplers at Radio Shack. They're for telephone use and
typically swap the entire cable, which is no good for
Ethernet - unless you have two of them in the cable,
connecting three short cables into one long cable.
This article is for folks who are ready for the next step
- permanently connecting their machines in multiple rooms.
We're going to cut holes in drywall and drill holes and
punch down cables just like the professionals.
Tools and supplies you'll need:
- 110-type punch down tool
- Fish tape
- Spool of CAT-5 cable (shielded twisted pair, 4 pairs,
- Wall plates and RJ-45 jacks with color-coded 110-type
- Electric drill (and maybe an extension cord)
- Wood-boring auger bit, 1/2î or bigger
- Some thin, strong wire or string, about 30 feet
- Measuring tape
- Hub or switch (see below)
- Patch panel or 110-type punchdown block with RJ-45
connectors (see below)
- Two people
Hub or switch?
A hub is a passive device that allows only one device on
the network to talk at a time. An Ethernet switch, by
contrast, is actually a type of router that allows multiple
devices to be talking at the same time. On a hub, all
devices must be running at the same speed; a switch can do
automatic speed conversion. So you might say, a switch is
completely better in every way, right? And you'd be mostly
right. The only problem you're likely to encounter with a
switch is "hunting," where both the device (say, your G4
Cube) and the switch are trying to autodetect the speed, and
both keep switching speeds to try to match each other, and
they never manage to agree.
Nevertheless, if you're going to all this work and
expense, be forward-looking. Using CAT 5 wire ensures you
can run both 10mb/s and 100mb/s; using a switch allows you
to intermix fast and slow computers on your LAN, so you can
gradually transition your network into the fast lane.
Locating the hub
The goal is to put jacks in the walls, about 18î
from the floor, all wired to a centrally- located hub. So,
the first decision to make is where to put the hub. Ideally
it will be in a room which is not fully drywalled, which is
not very crowded, and where a large bulk of wires will not
be considered unattractive. In my house there is a laundry
room which has no drywall (the walls are not "closed"), and
has easy access to a small attic.
If you can find one, a nice thing to have is a 110-type
punchdown block prewired with RJ-45 (8-pin modular) jacks.
Some with jacks are even color-coded! If you've got lots of
money you can get a patch panel with 110-type punchdown
positions designed for this job. The wires to the rooms can
be punched down, then short patch cords used to connect to
ports on the hub. If you can't find one like that, you'll
need to crimp ends on the cables coming from the walls --
something I'm rather leery of.
The color coding
The pairs of the signals in the wires are color-coded
thusly: blue/white and white/blue, orange/white and
white/orange, green/white and white/green, brown/white and
white/brown. The first named color is the main color, the
second color is a stripe around it, so the first pair is
blue with a thin white stripe and white with a thin blue
stripe. Only two of these pairs are used for 10baseT; all
four are used for 100baseT.
The wall plates
The wall plates that are easiest to use have three main
components. First, there is a plate that has a square hole
accepting a modular plug-in. Then, there is the RJ-45 jack
itself that plugs into the square hole. Get one that is
color-coded in accord with the previous paragraph and can be
punched down with the 110 tool. Finally, there is a piece
that functions as a box. I prefer the metal kind - you push
it into a hole in the drywall and bend some large U-shaped
tabs around to hold it in place. You can also get what's
called an "old work box." The old work box gets pushed into
the hole in the drywall; you then tighten bolts on either
side which press tabs against the other side of the drywall.
You do not need a complete enclosure, because the data wires
Getting into the walls
The easiest walls to get into are ones that have drywall
on one side only. You can cut a hole with a knife or sabre
saw, mount the box, punch the wire down on the connector,
push it into the plate, bolt it to the box, and voila. This
will work, for example, in the room adjoining the room where
the hub is mounted.
To get into a closed wall, you need to be able to get to
one side of the wall from somewhere you can drill. The
basics of wall framing are: a 2x4 across the bottom, a 2x4
across the top, and vertical 2x4's, called "wall studs"
spaced every 16 inches center-to-center, or "on center." You
can find where the studs are with a stud finder, or by
tapping the wall, or by looking for visible nails.
We'll start with an upstairs interior wall. From the
attic, find the top of the wall. You may be able to measure
from a common point, or it may be apparent from electrical
wiring going down, or by a piece of wood at the top, or
edges of the ceiling drywall. Down in the room below,
identify a nice place for a jack, away from the electrical
wiring, centered between two studs, and make a small hole
18î from the floor. Measure from an easily identified
reference point - say, the corner of the room - to the new
hole. In the attic, measure the same distance from the same
reference point and, using the auger bit and electric drill,
drill through the wood down into the wall. Have your
assistant below shine a flashlight into the hole in the
room, and see if you can see it from the hole above. If
there is no insulation, you'll be able to see the light
(that's why I suggest interior walls).
If you don't see the light, there may be a firestop - a
horizontal board running between the two wall studs. This is
unusual in interior walls. If you know they're there, you
can use drill extensions and other expensive tools to get
through - or you can mount your jacks above the firestop,
which is much easier.
Now you have verified the holes, enlarge the lower hole
to the rectangular shape needed for the bendaround box or
the old work box, whichever you have. Poke the fish tape
down through the upper hole slowly until your assistant
grabs it through the lower hole. Have your assistant tie the
string or thin wire to it. Pull it back up through the upper
hole. Now tie the CAT-5 cable to the string or thin wire,
and have your assistant pull it back down through the lower
hole, with about 12 inches of slack. Go down to the room,
punch down the jack and mount it as above.
How about downstairs rooms? It's considerably harder, but
the technique is basically the same, just from underneath
instead of above. The reason it's harder is because of two
things: first, there are floor joists going across the
floor; second, the subfloor beneath the walls makes it
difficult to identify where the walls are.
One technique that you can use for the difficult cases is
to make a hole on both sides of a wall - or floor to ceiling
- and put a plate on each side with a short piece of CAT5
between them. Walls are usually only 3-3/4î apart -
the width of a 2x4; floor to ceiling below is from 8 to 10
You can get a crimping tool and make your own workstation
cables, by crimping the ends on. Note, however, that if you
have a patch panel or punchdown block with connectors as
described above, you can use premade workstation cables.
They cost more, but poor cable connections are one of the
leading problems in small LANs. I strongly advise getting
premade cables. Micro Center has them in a variety of
lengths and colors. Sure, it's more expensive than making
your own cables - but if you have a problem, how valuable is
Your Growing Network
To connect a DSL modem or a cable modem to your network,
you'll need a swapped cable to connect it to your hub or
switch. Next, you may want to add a router so that multiple
machines can connect to the Internet at a time. When you get
your next printer, look for an Ethernet connection with
AppleTalk and TCP/IP support, plus Postscript, of course.
Keep a notebook with records of how each machine is
configured, with addresses, interfaces and other notes for
quick reference. Share your printers, and set up shared
folders on each computer. Think about your naming
convention: if you name a computer after its user, what
happens when that user gets a new computer and passes the
old one on to someone else?
AppleTalk is a networking protocol that works with very
minimal management. Still, don't think of a network as
something you set up once and forget. A network is not a
static, unchanging thing like a mountain - it's always
growing, changing, adapting, like a tree. It may take a
little extra care and nourishment. But once you have a
network, you can't go back to the old way of doing things -
it's that much different, and better.