networking - What's wrong with my custom patch cables?

18
2014-04
  • stu42j

    I have a box of bulk Cat5e riser cable left over from when I had my house wired. I figured I could use this to make some custom length cables for connecting my computers, switches, etc. I had a crimper already so I bought a bag of RJ45 plugs. I made a few cables several years ago, but my experience/knowledge with this sort of thing is minimal.

    None of my cables are working. I don't have a tester so I just plug the cable into a computer and switch but I get no link light. I wired them them all straight-through (T568A) and visual inspection doesn't show any problems.

    Any ideas what I might be doing wrong?

    Update: I just ordered a cheap cable tester on eBay so maybe that will help.

  • Answers
  • rob

    Double-check that the ends are on all the way. When you look through the end of the connector, you should be able to see the shiny copper tips of all the wires flush with the end of the connector.

    If that's not the problem, it might be that you're getting crosstalk if you didn't follow the proper pinout.

    Be sure to wire them correctly, according to the TIA-586B standard. There's a howto at http://www.edpscomputing.com/network.htm which you can use (scroll to the bottom).

  • Spiff

    The other answers hinted at this, but I'm going to underscore it:

    Pins 4 & 5 (the centermost two pins) must be on the same twisted pair.

    Pins 3 & 6 (the pins just outside of 4 & 5) must be on the same twisted pair.

    If you wired it "straight-through" as you said, without knowing about the special pairing requirements, then you probably did your pairs like this: (1 & 2), (3 & 4), (5 & 6), (7 & 8). That just won't work. You would've got pins 1, 2, 7, and 8 right, but pins 3, 4, 5, and 6 would be wrong. (I'll spare you the details of balanced-line transmission and noise cancellation.)

    So follow the TIA/EIA-568-B standard as rob mentioned. Not only will it get the pairings right, but it'll make it easier when you or someone else has to work on those cables again.

    One other thought: Inside the RJ-45 plugs, you know the little teeth that pierce through the insulation of the individual wires? The design of those teeth can be optimized for solid conductor wire, or optimized for stranded wire, or designed to work okay with either. If you happened to get the kind of RJ-45 plugs with teeth optimized for the opposite kind of wire from what you're using them on, they may not work reliably.

  • Mark Robinson

    It going to be hard to tell you what exactly you did wrong. My advice would be to cut the plugs off and start over following a guide like this one from Lanshack.

  • Bigbio2002

    I've just learned how to make these cables at work, and I've had good luck so far, so let me tell you the procedure I use:

    1. Carefully strip about an inch and a half of outer plastic from the cable
    2. straighten out each of the individual wires and get them in the proper order. Spiff listed the order correctly, or you can google the specification to get the "official" color ordering. (note: the actual color doesn't matter, just that the colors are paired and both cable ends are identical)
    3. NOW is the time to trim the wires to length; You should trim them to about a centimeter, or you can look at an RJ45 head for guidance. The wires should be long enough to reach the end of the canal so the gold heads can be pushed into them when crimped, and the outer sheath should be in position to be grabbed by the square hole thingy on top of the head.
    4. Stick your head on and double check to make sure that the wires reach all the way down the canal so it gets properly crimped.
    5. CRIMP! Squeeze it down all the way and make sure you seal it tight. Then visually inspect everything for a tight seal, and test once you have your testing unit. Hopefully it should work.

    Crimpin' bitchez, now that's what it's all about, yo.

  • kbyrd

    Ok maybe I'm overthinking it, but as another poster said this is going to be hard for us to debug. You could get a multimeter and do a continuity check to figure out which pin on one end is wired to which pin on the other end. Then check to make sure it's TIA-586A|B. It'll also tell you whether you're making contact at all.

    If the cable is as you expect electrically, then I would start looking at things like interference or cable length. Are they too short? Too long? Bad shielding? I can't imagine simple interference is preventing a link light, so it's probably not electrically connected.

  • goblinbox

    Wire colors: wo = white orange o = orange wg = white green bl = blue wbl = white blue g = green wbr = white brown b = brown

    Pin out for CAT-5 Plug = wo o wg bl wbl g wbr b

    RJ45 for an Ethernet jack (Ethernet is on 1-2-3-6): 1=wo 2=o 3=wg 6=g

    Crossover: 1-3 and 2-6 are reversed (order is 3 6 1 4 5 2 instead of 1 2 3 4 5 6)

  • user33115

    I know you already commented that you did wire T568, but for anyone that isn't aware of how to crimp Cat5 cables, wikipedia has a good explanation:

    http://en.wikipedia.org/wiki/TIA/EIA-568-A#Wiring


  • Related Question

    networking - What is the difference between various cable types like Cat 5, Cat 5e and Cat 6?
  • David Hayes

    I'm just about to move house, so I'm going to have to disconnect and re-wire my network. Pretty much all the devices I have support Gigabit Ethernet. Should I go out and buy some decent network cables (and if so what type) or should I continue using my mix of Cat 5 cables I've acquired over the years.

    Does the type of cable really make a difference to my LAN performance?


  • Related Answers
  • Spiff

    What Is The Difference Between Cat 5, Cat 5e, and Cat 6 Cable?

    If you’re researching the different types of twisted-pair copper cable used to transmit data in network and home theater applications, then it’s likely that you will repeatedly come across the terms Category 5 (Cat 5), Category 5e (Cat 5e) and Category 6 (Cat 6). Organizations such as the Telecommunication Industry Association (TIA) and Electronic Industries Association (EIA) set specific product standards, and these guidelines have resulted in cables being classified into various categories based on their performance levels. Just in case you’re not too familiar with cabling terminology, we at CableOrganizer.com would like to provide you with a few straightforward definitions and statistics on these three common grades of network cable, to help you better choose the right one to fit your needs.

    Cat 5: Out of the three types of cable we’ll be discussing, Category 5 is the most basic. Cat 5 cable is available in two varieties: Unshielded Twisted Pair (UTP), the type widely used in the United States, and Screened Twisted Pair (SCTP), which has shielding to provide a measure of extra protection against interference, but is rarely used outside of Europe. Cables belonging to Category 5 are either solid or stranded: Solid Cat 5 is more rigid, and the better choice if data needs to be transmitted over a long distance, while Stranded Cat 5 is very flexible and most likely to be used as patch cable. Cat 5 cable can support 10, 100, or 1000 Mbit/s Ethernet. The 1000BASE-T standard for Gigabit Ethernet over UTP was designed to work over up to 100 meters of plain old Cat 5.

    Cat 5e: Cat 5e (which stands for Category 5, enhanced) cable goes along the same lines as basic Cat 5, except that it fulfills higher standards of data transmission. While Cat 5 is common in existing cabling systems, Category 5e has almost entirely replaced it in new installations. Just like Cat 5, Cat 5e can handle data transfer at 1000 Mbit/s, and is suitable for Gigabit Ethernet. Cat 5e experiences much lower levels of near-end crosstalk (NEXT) than Cat 5.

    Cat 6: Of the three cable categories we’re discussing, Category 6 is the most advanced and provides the best performance. Just like Cat 5 and Cat 5e, Category 6 cable is typically made up of four twisted pairs of copper wire, but its capabilities far exceed those of other cable types because of one particular structural difference: a longitudinal separator. This separator isolates each of the four pairs of twisted wire from the others, which reduces crosstalk, allows for faster data transfer, and gives Category 6 cable twice the bandwidth of Cat 5! Cat 6 cable is ideal for supporting 10 Gigabit Ethernet. Since technology and standards are constantly evolving, Cat 6 is the wisest choice of cable when taking any possible future updates to your network into consideration. Not only is Category 6 cable future-safe, it is also backward-compatible with any previously-existing Cat 5 and Cat 5e cabling found in older installations.

    Source and more information

  • Peter Mortensen

    Gigabit Ethernet is designed to slow down if the cables are picking up interference, but the quality of installation is probably as important as the cable itself. Ethernet over copper is always unreliable if you go over 100 m, so of course higher quality cable is more important at greater distance.

    But be careful not to kink the cables while you are laying them or bend them too tightly, and any solid cable needs to be untwisted more carefully. You only want solid cables if you are installing to new jackpoints, and then you use the normal stranded patch cables from the jackpoint to the computer or switch (ie. solid cable for permanent wiring only).

    Don't put plugs onto solid cables; solid patch cables are more trouble than they're worth, so use stranded (flexible) cable for that.

  • Adrien

    Depending on how old they are and how badly they've been abused, your existing cables may be starting to deteriorate.

    Plus, if you replace them, you can do spiffy color-coding.

    Cat 5e can theoretically handle 1gig-e, while Cat 6 can handle 10gig-e; Cat 6 is typically more expensive. Basically, if you buy a quality cable, Cat 5e should do it.

  • Chris Nava

    Cat5e should be good enough for the next few years.

    If you don't mind crimping your own connectors you can buy a bulk spool of cable from you local big box hardware store. It's much cheaper than buying lots of shorter cables and you can make custom lengths.

  • Barry Brown

    I'd start looking into buying new Cat5e or Cat6 cables. Cat5e cables are about the same size as Cat5. Cat6 cables are a bit thicker. I just threw out most of my old Cat5 cables and replaced them with pre-made Cat5e ones.

    I like monoprice.com for cables. I don't crimp my own cables anymore; it's too hard to get a good connection using an inexpensive (~$30) crimper. If time=money, it's much cheaper for me to buy pre-crimped cables of various lengths.

  • Peter Mortensen

    No, it's not so simple.

    Cat 6 is also limited to 100 metres length maximum, less actually, and its operating efficiency and reality is dependent on other factors such as age, handling, damage, copper quality, connection efficiency (24 gauge instead of 22 can create punching problems), environmental factors and so on as well, as the bandwidth actually being used.


    While the above is true, Cat 6 is limited to 100 m for Cat 6 performance. The point of other comments is correct in that, if running longer than 100 m, you might still get good Cat 5e grade performance out of a Cat 6 cable, when a Cat 5e would not be able to transmit the signal as well.

  • Peter Mortensen

    I wired my house 10 years ago with Cat 5. By that time, I was told that I should just use Cat 4, since Cat 5 is expensive. If I put Cat 4, I would not be able to take advantage of the current Gigabit speed.

    Currently, Cat 7 is out, but think for the future.

  • Peter Mortensen

    For the typical home network, Cat 5e will work for years to come. Cat 6 is a slightly different animal from an operational and installation point of view and not worth the effort unless the environment is hostile (read that as full of interference producing devices).

    Not too many homes, or even business locations for that matter, are hostile enough to justify Cat 6. Self-proclaimed 'experts' in places like Best Buy will tell you Cat 6 is the way to go, but most of them have no clue what they're talking about, or at least I haven't met one in my 20+ years of electrical and network cabling experience.