10BaseT Wiring Notes

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.