TechSpot

cat5 and testing

By saint01
Jul 20, 2004
  1. Ok, so I have read all of the topics on the Internet that say that you can't take cat5 longer than 100 meters. I know people that have, but they say that the speed just drops to about 10mb per second.

    I need to run the cat5 about 400 ft and then another 175 ft. I am going to put a router inbetween to kind of, rejuice, the signal.

    Questions.

    1. anyone know for sure based off of experience what the actual limit on cat5 is?

    2. I have my l-com tester. I currently have about 500ft capped on both ends and am testing it, yet don't really know what the readout means. Numbers "4&5" and "7&8" are flashing. Oh, btw, I have model dxb64a.

    Any help with this is much appreciated!
     
  2. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    Well, different testers give different visual aids to let you know what the result is.

    Here's what I think of your readings...

    Blinking usually indicates a broken connection (on most of the testers I've used)

    Coincidentally, wires 4/5 and 7/8 are not used in RJ-45 ethernet cabling. It is possible that perhaps your cable ends do not have connectors for wires 4,5,7 or 8. I've never anything like that though, but it is far too much of a coincidence.

    So it sounds like your cable will work fine, since the "erroneous" wires appear to be null anyway.

    Just make sure you put the RJ-45 ends on the right direction, if this is the case. If you put on backwards (So that 1 and 2 ends up being 7 and 8), your cable won't work for sure. :)

    I've been told 1Gbps network cables use all wires, but I've never made one so I don't know.

    I am unware of any problems caused by not using 4,5,7,8 (all wires). There might be some sort of redundancy or ground uses for them, but that's about all I can think of. They are not necessary for data transfer.
     
  3. Goalie

    Goalie TS Rookie Posts: 703

    In response to question 1....

    I've seen cables as long as 320 feet work fine. After that, it gets real hit and miss, depending on environmental conditions (stuff like flourescent light fixtures near the cable, etc.) I should mention that I've seen cables less than 100ft go south for many many reasons, too (crimps, line noise, cut lines, bad attenuation, bad pin in the jack, you name it...)

    300 is what I've been told by my boss, and experienced and knowledgeable man, is the safe point. After that he says it gets interesting.

    1gbps cables do indeed use all 8 pairs.

    Standard cat5 wiring specification, while different standards use different twist pairs in the locations, it's still 123 and 6 for the wires. We always used blue/orange, there are plenty of standards out there. Blue Orange seems to be the most common.

    Now.. in truth.. the cable works fine for longer lengths, however it's the TCP/IP standard which usually becomes the limiting factor, and there's not a whole lot you can do for that.

    To best divide the workload, I'd go something like two cables of 250, and put a non-transparent repeating device in the middle. Some sort of switch/bridge, although I'm not sure the best type in the situation. I'll see if I can find a better answer for you later.
     
  4. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Posts: 4,919   +9

    Not in half duplex cables, but they're used in full duplex mode.
     
  5. Goalie

    Goalie TS Rookie Posts: 703

    Well, if I keep seeing avatars like that pink kitty, my cable might end up using 4,5,7,8 in half duplex.

    Bring the headbanger back. Much more appropriate, esp. in reference to a thread like this. :)
     
  6. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    Thanks for the info. :)
     
  7. RealBlackStuff

    RealBlackStuff TS Rookie Posts: 8,165

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