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TUCoPS :: PC Hacks :: 10wiring.txt

10baseT wiring tips





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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