568b cable standard

marku2

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ETHERNET CABLE: COLOR-CODE STANDARDS

The information listed here is to assist Network Administrators in the color coding of Ethernet cables. Please be aware that modifying Ethernet cables improperly may cause loss of network connectivity. Use this information at your own risk, and insure all connectors and cables are modified in accordance with standards. The Internet Centre and its affiliates cannot be held liable for the use of this information in whole or in part.

T-568A Straight-Through Ethernet Cable



The T-568A standard is supposed to be used in new network installations. Most off-the-shelf Ethernet cables are still of the T-568B standard; however, it makes absolutely no functional difference in which you choose. "" INSERT BY MARK ( i would stick to the T-568B ) """

T-568B Straight-Through Ethernet Cable



Both the T-568A and the T-568B standard Straight-Through cables are used most often as patch cords for your Ethernet connections. If you require a cable to connect two Ethernet devices directly together without a hub or when you connect two hubs together, you will need to use a Crossover cable instead.

RJ-45 Crossover Ethernet Cable



A good way of remembering how to wire a Crossover Ethernet cable is to wire one end using the T-568A standard and the other end using the T-568B standard. Another way of remembering the color coding is to simply switch the Green set of wires in place with the Orange set of wires. Specifically, switch the solid Green (G) with the solid Orange, and switch the green/white with the orange/white.

Ethernet Cable Instructions:

  1. Pull the cable off the reel to the desired length and cut. If you are pulling cables through holes, its easier to attach the RJ-45 plugs after the cable is pulled. The total length of wire segments between a PC and a hub or between two PC's cannot exceed 100 Meters (328 feet) for 100BASE-TX and 300 Meters for 10BASE-T.
  2. Start on one end and strip the cable jacket off (about 1") using a stripper or a knife. Be extra careful not to nick the wires, otherwise you will need to start over.
  3. Spread, untwist the pairs, and arrange the wires in the order of the desired cable end. Flatten the end between your thumb and forefinger. Trim the ends of the wires so they are even with one another, leaving only 1/2" in wire length. If it is longer than 1/2" it will be out-of-spec and susceptible to crosstalk. Flatten and insure there are no spaces between wires.
  4. Hold the RJ-45 plug with the clip facing down or away from you. Push the wires firmly into the plug. Inspect each wire is flat even at the front of the plug. Check the order of the wires. Double check again. Check that the jacket is fitted right against the stop of the plug. Carefully hold the wire and firmly crimp the RJ-45 with the crimper.
  5. Check the color orientation, check that the crimped connection is not about to come apart, and check to see if the wires are flat against the front of the plug. If even one of these are incorrect, you will have to start over. Test the Ethernet cable.
Ethernet Cable Tips:

    • A straight-thru cable has identical ends.
    • A crossover cable has different ends.
    • A straight-thru is used as a patch cord in Ethernet connections.
    • A crossover is used to connect two Ethernet devices without a hub or for connecting two hubs.
    • A crossover has one end with the Orange set of wires switched with the Green set.
    • Odd numbered pins are always striped, even numbered pins are always solid colored.
    • Looking at the RJ-45 with the clip facing away from you, Brown is always on the right, and pin 1 is on the left.
    • No more than 1/2" of the Ethernet cable should be untwisted otherwise it will be susceptible to crosstalk.
    • Do not deform, do not bend, do not stretch, do not staple, do not run parallel with power cables, and do not run Ethernet cables near noise inducing components.


Basic Theory:



By looking at a T-568A UTP Ethernet straight-thru cable and an Ethernet crossover cable with a T-568B end, we see that the TX (transmitter) pins are connected to the corresponding RX (receiver) pins, plus to plus and minus to minus. You can also see that both the blue and brown wire pairs on pins 4, 5, 7, and 8 are not used in either standard. What you may not realize is that, these same pins 4, 5, 7, and 8 are not used or required in 100BASE-TX as well. So why bother using these wires, well for one thing its simply easier to make a connection with all the wires grouped together. Otherwise you'll be spending time trying to fit those tiny little wires into each of the corresponding holes in the RJ-45 connector.

use the b standard it might save you hrs of headaches,always bench test with a short store bought cable
set the system up first
example on a bench or table get all your cameras plugged in to the nvr or poe switch set the unit up make sure all cameras work mark them cam1 cam2 etc
and when you fit everything and make your cables up and something is not working its easy to fault find
example cam2 no signal ir on, OK double check cable ends or cut off and make a new end some times the
crimp tool doesn't crimp down ( or i didn't crimp it correctly or i didn't cut the wires straight before i put it into the connector plug) done it quite a few times myself
get this part right it makes life so easy
 

larryhagman

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I read on some threads about T568B being VITAL. I am about to buy a load of cable (when I decide between Cat5e and Cat6, any votes?) and first time attempt at crimping,cutting my own cables. Do I still need to worry about this T568B thing? It sounds pretty complex, I dont really understand why it needs doing, crossing things around seems like a recipe for disaster and I can make enough of those on my own :D . Is the advice to do T568B standard when making ethernet cables for PoE CCTV, still valid in 2020?
thanks
 

bguy

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It's absolutely critical that you wire it correctly. I had a customer that reported an issue with a cable, and it was wired with the pairs all next to one another. While it will test ok on a cheap continuity tester, it failed big time with a Fluke LAN meter.
 

sebastiantombs

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The big trick is to use the same standard on all your connections simply to keep it simple. There is no special magic in the location of the pairs, pins used for each color pair. 568A will work just as well as 568B. The problem comes when they get mixed on the same cable. As long as pins 1&2, 3&6, 4&5, 7&8 are the same actual pairs on both ends everything will work just fine.
 
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larryhagman

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Oh, ok thanks. I have yet to wire a single ethernet cable manually. I have always just bought them whatever length required. So this talk of pairs is a bit beyond me. I just wanted to get a link/guide to follow when it all arrives. The mention above of 'straight through' or 'crossover' cables, had me a bit confused. I will read it again when the cable arrives. I am getting cat6 since I can't decide between that and cat5e (and price is not much different). I think that means the cat5 connectors I ordered will be no good and i need cat 6 connectors. lots to learn, I am so pressured for time, one thing I absolutel MUST avoid is wiring up only to find I have to cut and do it all again!
 

fenderman

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Oh, ok thanks. I have yet to wire a single ethernet cable manually. I have always just bought them whatever length required. So this talk of pairs is a bit beyond me. I just wanted to get a link/guide to follow when it all arrives. The mention above of 'straight through' or 'crossover' cables, had me a bit confused. I will read it again when the cable arrives. I am getting cat6 since I can't decide between that and cat5e (and price is not much different). I think that means the cat5 connectors I ordered will be no good and i need cat 6 connectors. lots to learn, I am so pressured for time, one thing I absolutel MUST avoid is wiring up only to find I have to cut and do it all again!
Its really really simple. Forget about crossover etc. Wire it to 568B. Done.
 

larryhagman

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So from that post above I just need to do the one entitled: T-568B Straight-Through Ethernet Cable ?
Thanks
 

DsineR

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Correct...
T-568B Straight-Through Ethernet Cable




Both the T-568A and the T-568B standard Straight-Through cables are used most often as patch cords for your Ethernet connections.
 
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