10BaseT Wiring Notes Version 1.1
12 Sep 1991
From the recent number of questions on CompuServe, there seems to
be a need for a few notes on how to wire a 10BaseT network. The
information shown here should be very useful for the first time
installer. Much of it is derived from Hewlett Packard's excellent
tech manuals in addition to several cable vendors catalogs.
Another useful download about 10BaseT concepts in the PD10BA.TXT
file in Lib 17. For the most part I have avoided inserting subtle
prejudices but I have not been entirely successful <grin>.
This should answer some early questions in getting started.
Please send corrections, comments and suggestions to me so we can
make this more useful.
Good Luck.
Steve Fleming
Kabi-Pharmacia, Inc
Raleigh, NC
76424,1556
Terminology ---------------------------------------------------
AWG - American Wire Gauge, the standard measure for the diameter
of a wire. As the numbers increase, the wire diameter decreases.
Normal wire for 10BaseT is 22 or 24 AWG.
Conductors - A piece of wire. For 10BaseT purposes it is solid,
copper wire. Don't use stranded.
Crimper - A plier like device used to attach connectors to the end
of cables.
Data Cable Levels - A cable grading scheme used by cable
manufacturers to identify the designed transmission speed for
a given cable.
EMI/RFI - Electro-magnetic Interference / Radio Frequency
Interference. The electrical signals in the air that you don't
want in your cables. If someone tells you there is no EMI/RFI
in their office building, just turn on a radio.
Hub - Also called a Concentrator. This is the central device in
a 10BaseT network. Workstations are wired into its ports ( from
3 to 132 ) and the hub makes sure connections are good and passes
the signals. Depending upon the level of sophistication and
management, these can cost from $100 to $200 and up per port.
IBM Cable Types - IBM, of course, has its own method of defining
cable types.
Impedance - An electrical characteristic that measures opposition
to the flow of an alternating current in a wire. Just like
resistance is to a direct current flow. AC signals get very
upset when cables of different impedances are connected.
Link Beat - Once a second the Hub sends a signal to the
workstation. If the workstation does not respond, the hub
"segments" that workstation out of the net. This should prevent
a bad cable or card from bringing down the whole network.
NEC - National Electric Code. NEC rates the cable for fire
resistance and such. If you are going to run your cable above
the ceiling in a space used for ventilation (a plenum), then you
have to use plenum rated cable. This is a more expensive (Teflon
sheath versus PVC) but is required to meet fire codes.
NIC - Network Interface Card.
Punch (down) Block - A device used in a central closet for managing
wires. Available in a 66 or 110 model. The 110 is the new,
electrically superior model, but the 66 seems to work fine. Wires
are attached with a Punch (down) Tool. Punch Blocks are usually
attached to the wall in a wiring closet on a patch panel.
RJ-45 - A small plastic connector used on the end of a four pair
cable. RJ-11 is the smaller one used for telephone connections.
Satin cable - Four parallel wires (0 twists) used for telephone
only. One comes with every modem. Not for network use.
STP - Shielded Twisted Pair. One or more twisted pairs inside an
electrically conductive sheath (usually aluminum foil) that
protects the pairs from outside interference. The shield should
be grounded at the hub end. STP generally has an impedance of
150 ohms.
Twisted Pair - Two conductors that wrap around each other to form
a pair. An extremely vague term that should be banned from
CompuServe networking forums since there are many kinds of
"twisted pair".
UTP - Unshielded Twisted Pair. One or more twisted pairs inside
an insulating sheath. UTP generally has an impedance of 100 ohms.
Cable Types ---------------------------------------------------
Cables are grouped in categories according to various factors.
Levels specify a certain speed rating on the cable. IBM Cable
Types specify a certain kind of cable. Please note that what is
shown below is a very abbreviated description. Each Level or
Type has specific physical and electrical characteristics and
those details can be found in most cable vendors' catalogs. The
number of twists per foot is at least two for data grade cable.
Data Grading Levels
These cables may be UTP or STP. The higher level cables have
better conductors, insulation and more twists per foot.
Level 1- Used for up to 1 Megabit Per Second (MPS)
Level 2 - Used for up to 4 MPS
Level 3 - Used for up to 16 MPS
Level 4 - Used for up to 20 MPS
Level 5 - Used for 150 ohm data grade applications. STP only.
IBM Type Designations
Type 1 - Two pair of 22 AWG, each pair foil wrapped inside
another foil sheath that has a wire braid ground. This is
usually what most people think of as "STP".
Type 2 - Type 1 with 4 telephone pair sheathed to the outside
to allow one cable to an office for both voice and data.
Type 3 - Four pair of unshielded 22 or 24 AWG, each pair wrapped
at least twice per foot. This is what most people think of
as "UTP"
Type 4 - There isn't one!
Type 5 - Fiber optic
Type 6 - Two pair of stranded, shielded 26 AWG to be used for
patch cables.
Type 7 - One pair of stranded, 26 AWG wire.
Type 8 - Two parallel pairs (flat wires with no twist) of 26 AWG
used for undercarpet installation.
Type 9 - Two pair of shielded 26 AWG used for data. Doesn't
carry data as well as Type 1 due to smaller conductors.
Cable Planning ------------------------------------------------
Wiring should be run from each workstation (or node) back to a
central wiring closet. Hubs can be connected by UTP thru
the ports with a cross over cable or by coax thru the BNC
connector.
Maximum from hub to workstation is 100 meters.
Maximum distance from hub to hub using UTP is 100 meters.
Maximum distance from hub to hub using RG-58 coax is 185 meters.
Minumum distance from hub to hub using RG-58 coax is .5 meters.
Maximum number of punch blocks or patch panels (i.e. breaks in
the cable) is 4.
Maximum number of devices on an RG-58 coax cable segment is 30.
Maximum number of cascaded hubs is 4. In other words, from one
node to any other the signal cannot pass thru more than 4 hubs.
Wiring Diagrams -----------------------------------------------
Important Note - The RJ-45 is the key to the whole system. The NIC
and Hub must have the cables done in a certain way in order to
work. The punch blocks, patch panels, etc, really don't matter as
long as the wire continues correctly from end to end. HOWEVER, do
yourself an enormous favor and do your wiring consistent with
industry standards. It's rough on the knees checking under your
car for bombs after you move on to another job and someone else has
to live with your handiwork.
Four pair wire is the standard with Pair 1 as Blue, Pair 2 as
Orange, Pair 3 as Green and Pair 4 as Brown. Colors are always
shown with the Base Color first, then the Stripe Color. The
RJ-45 is wired as follows:
Pin 1 White/Orange Transmit -
Pin 2 Orange/White Transmit +
Pin 3 White/Green Receive -
Pin 4 Blue/White
Pin 5 White/Blue
Pin 6 Green/White Receive +
Pin 7 White/Brown
Pin 8 Brown/White
Two notes - First, holding the cable in your left hand, with the
RJ-45 pins facing up, Pin 1 is the furthest away from you. Second,
the blue and brown pair are unused and there is a big discussion
on whether you can use them or not. The feeling seems to be that
digital telephone is OK, but analog telephone (modem, fax) is not
due to the high ring voltage. I am running digital phone in the
blue and some System 36 emulation in the brown without problems but
most of my stations are on short ( < 150 feet ) cables. Still, the
safe money says to use the cable solely for one 10BaseT node and
put everything else in another cable.
To make a Cross Over patch cable for hub to hub connections, wire
one end as follows:
One End The Other End
Pin 1 White/Orange Pin 1 White/Green
Pin 2 Orange/White Pin 2 Green/White
Pin 3 White/Green Pin 3 White/Orange
Pin 6 Green/White Pin 4 Orange/White
To make an RJ-45 Loopback tester, wire as follows:
Pin 1 White/Orange
Pin 2 Orange/White
Pin 3 White/Orange
Pin 6 Orange/White
On the 66 or 110 block, the white wire goes on top. Thus, going
down the block you have White/Blue, Blue/White, White/Orange,
Orange/White, White/Green, Green/White, White/Brown, Brown/White.
To wire a 25 Pair Telco connector, wire as follows: (Note that
HP may be different from your vendor)
Pin 26 White/Blue Port #1 White/Orange
Pin 1 Blue/White Orange/White
Pin 27 White/Orange White/Green
Pin 2 Orange/White Green/White
Pin 28 White/Green Port #2 White/Orange
Pin 3 Green/White Orange/White
Pin 29 White/Brown White/Green
Pin 4 Brown/White Green/White
Pin 30 White/Slate Port #3 White/Orange
Pin 5 Slate/White Orange/White
Pin 31 Red/Blue White/Green
Pin 6 Blue/Red Green/White
Pin 32 Red/Orange Port #4 White/Orange
Pin 7 Orange/Red Orange/White
Pin 33 Red/Green White/Green
Pin 8 Green/Red Green/White
Pin 34 Red/Brown Port #5 White/Orange
Pin 9 Brown/Red Orange/White
Pin 35 Red/Slate White/Green
Pin 10 Slate/Red Green/White
Pin 36 Black/Blue Port #6 White/Orange
Pin 11 Blue/Black Orange/White
Pin 37 Black/Orange White/Green
Pin 12 Orange/Black Green/White
Pin 38 Black/Green Port #7 White/Orange
Pin 13 Green/Black Orange/White
Pin 39 Black/Brown White/Green
Pin 14 Brown/Black Green/White
Pin 40 Black/Slate Port #8 White/Orange
Pin 15 Slate/Black Orange/White
Pin 41 Yellow/Blue White/Green
Pin 16 Blue/Yellow Green/White
Pin 42 Yellow/Orange Port #9 White/Orange
Pin 17 Orange/Yellow Orange/White
Pin 43 Yellow/Green White/Green
Pin 18 Green/Yellow Green/White
Pin 44 Yellow/Brown Port #10 White/Orange
Pin 19 Brown/Yellow Orange/White
Pin 45 Yellow/Slate White/Green
Pin 20 Slate/Yellow Green/White
Pin 46 Violet/Blue Port #11 White/Orange
Pin 21 Blue/Violet Orange/White
Pin 47 Violet/Orange White/Green
Pin 22 Orange/Violet Green/White
Pin 48 Violet/Green Port #12 White/Orange
Pin 23 Green/Violet Orange/White
Pin 49 Violet/Brown White/Green
Pin 24 Brown/Violet Green/White
Pin 50 Violet/Slate Not Used
Pin 25 Slate/Violet
Faceplate Wiring ----------------------------------------------
The cable from the wiring closet usually will terminate on a
faceplate located in the general vicinity of the computer to be
connected. Below is how we are wiring them here. Please note that
your faceplates' wiring scheme and/or colors may be different from
what is shown here. Also, note that we wire Pins 4 & 5 for use with
digital telephone or System/36 connections. Our HP manuals indicate
that this is acceptable but may be in violation of the final 10BaseT'
specification. When looking at the front of the faceplate, the key
lock on the RJ-45 hole is down and the pins are on top. With this
view, Pin 1 is on the left and Pin 8 is on the right.
Pin 1 - Blue White/Orange
Pin 2 - Orange Orange/White
Pin 3 - Black White/Green
Pin 4 - Red Blue/White (tel)
Pin 5 - Green White/Blue (tel)
Pin 6 - Yellow Green/White
Pin 7 - Brown
Pin 8 - Grey
Potential Downfalls ------------------------------------------
Here are four areas where you might have problems with your
network.
1 - Don't use cable just because it's already installed. If you
have telephone grade, 4 pair cable installed replace it with the
right kind, either Level 3 or 4 or IBM Type 3. My local Anixter
dealer even came out with a Pair Scanner and helped me test ours
to determine the good from the bad and the ugly (most was good).
2 - Oddly enough, all RJ-45s connectors are not alike. Buy the
crimpers and connectors from the same company and plan on about
$100 to $150 for the crimper. It took me 2 crimpers and 3 sets of
connectors to get a pair that made good connections reliably.
3 - Before you start anything, get a clean blueprint of your
building and write "Cable Diagram" across the top. Keep it
accurate and up to date. Mark every cable with a cable number,
not a telephone extension.
4 - Nothing personal against telephone guys, but telephones will
work fine with lousy connections, poor wire, and very long
distances. Data gets upset with those things plus running the
cable near EMI sources. One patch panel here was installed on the
back side of the 220v Breaker Panels (hundreds of amps) for the
entire building and I was not interested in being an EMI test site.
Do not assume that because the person has been "pulling cable for
20 years" that they know what they are doing with data cable.
Casually ask things about maximum cable lengths and if you aren't
happy with the answers work closely with them as they do the work.
Remember, it's YOUR headache if the new cable is done improperly.
The End.
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