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.