The Hacker's Encyclopedia 1998

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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.