Stupid Cat5 wiring standard.

Discussion in 'OT Technology' started by deusexaethera, Oct 8, 2009.

  1. deusexaethera

    deusexaethera OT Supporter

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    For those of you who are unfamiliar with how telephone wiring works, an RJ45 (4-line) telephone cable is wired like so:

    Code:
    1  2  3  4  5  6  7  8
    |  |  |  |  |  |  |  |
    [COLOR=Sienna]4d[/COLOR] [COLOR=DarkOrange]4c[/COLOR] [COLOR=SeaGreen]4b[/COLOR] [COLOR=Blue]4a 5a[/COLOR] [COLOR=SeaGreen]5b[/COLOR] [COLOR=DarkOrange]5c[/COLOR] [COLOR=Sienna]5d[/COLOR]


    What all that shit means is, if you had four telephone lines on a single RJ45 cable, you would split it into four separate jacks by sending the center pair of wires to Jack 1, the two wires on either side of the center to Jack 2, etc. Pretty simple once you've done it a couple of times.

    But Cat5 is done differently. First of all, a single Cat5 connection requires 4 wires instead of 2, so you can only run two Cat5 connections through a single RJ45 cable instead of four. But that's not such a big deal, since you can always use a switch to get as many extra connections as you need. No, the problem is the way the wiring is hooked up:

    Code:
    [COLOR=Black]1  2  3  4  5  6  7  8
    |  |  |  |  |  |  |  |[/COLOR]
    [COLOR=Blue]1a 2a 3a[/COLOR] [COLOR=Green]1b 2b[/COLOR] [COLOR=Blue]6a[/COLOR] [COLOR=Green]3b 6b[/COLOR]


    So, there are several things to consider. First, it's obvious that Cat5 wiring avoids using wires 4 and 5 for a single connection (which is all most setups ever use) in case you want to run a telephone line through the same cable. That's fine, there's nothing wrong with that. The problem is that Cat5 wiring doesn't even use pins 4 and 5 at the wall jack, which you know will only ever be used for network connections! (Presumably, if you ran a telephone line across the same cable, the wires for the phone line would go to a telephone jack so it wouldn't matter how the network jack was wired up.)

    Why is this a problem? Because it means that RJ45 network splitters (used to send two Cat5 connections along the same cable) absolutely must be wired differently than RJ45 telephone splitters, and it is absofuckingregoddamnlutely IMPOSSIBLE to find an RJ45 telephone splitter! Sure, I bet the phone company has a couple lying around somewhere, but nobody else does. Which means that I have to make my own goddamn splitters so I can send two phone lines across a cable with more than enough wires to handle it, because the only splitters I can buy don't damn well connect any of the wires to the pins that telephones are designed to use!

    This would've been a better layout for Cat5 wiring:

    Code:
    [/COLOR][/FONT][/COLOR][/COLOR][/FONT][FONT=Courier New][COLOR=Sienna][COLOR=Black]1  2  3  4  5  6  7  8
    |  |  |  |  |  |  |  |[/COLOR]
    [COLOR=Green][FONT=Verdana][COLOR=Black][FONT=Courier New][COLOR=Blue]3b[/COLOR] [COLOR=Green]3a[/COLOR] [COLOR=Blue]4b[/COLOR] [COLOR=Green]4a 5a[/COLOR] [COLOR=Blue]5b[/COLOR] [COLOR=Green]6a[/COLOR] [COLOR=Blue]6b[/COLOR][/FONT][/COLOR][/FONT][/COLOR][COLOR=Green][FONT=Verdana][COLOR=Black]
    Why would it have been better? Because the first Cat5 connection would still avoid wires 4 and 5, so they would still be open for either a telephone line or a second Cat5 connection to be included, and it would also mean that the fucking splitters would work the same no matter what you were trying to hook up -- whether it be two phone lines, two network lines, or one of each, they all would work fine.

    I need to send out another round of flyers to people:

    CALL ME
    BEFORE YOU
    DO ANYTHING!

    Except I wouldn't be able to answer, because the fucking wiring doesn't work. :squint:

     
    Last edited: Oct 8, 2009
  2. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    Don't be niggardly, run home runs to the switch.
     
  3. caddymac

    caddymac New Member

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    RJ45 splitters went out of fashion with 10Mbit network connections.
     
  4. Hate Crime

    Hate Crime Don't Hate OT Supporter

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    Why do you nigger-rig everything.

    Every post you make, you cheap out on every fucking thing.
     
  5. trouphaz

    trouphaz New Member

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    who the fuck bothers doing shit like this? a friggin switch cost next to nothing these days.
     
  6. BlazinBlazer Guy

    BlazinBlazer Guy Witness to The De-Evolution of Mankind.

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    :werd: Cat5e isn't THAT expensive unless you're having to use riser rated cable, and switches are cheap as fuck. Run home runs, it makes all of this easier and in the event that you have to troubleshoot something, makes diagnosis and repair much simpler.

    The time you invest to do it the ass-backward way will end up costing more in the long run than doing it right in the first place.
     
  7. deusexaethera

    deusexaethera OT Supporter

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    No no no, I'm not using this for a network connection. I'm using it for a telephone connection. My office is wired with RJ45 jacks all around, and all of our phones use RJ45 cables, but I need to send two phone lines into one of the of the offices and there's only one wall jack available for it. But nobody makes RJ45 line splitters that are designed to work with telephones, only for network cables, and the wiring scheme for Cat5 seems to be specifically designed to be incompatible with the wiring scheme that telephones use. That means that RJ45 network line splitters CANNOT be used to split RJ45 telephone lines. But as I demonstrated, it would've been perfectly feasible to design Cat5 jacks so they could be used for a single phone line, or two phone lines, or a single network line, or two network lines, or even one of each -- but they didn't do that. That was a shortsighted thing to do.

    Anyway, I took the RJ45 network line splitters I bought, took them home, cut the circuit board traces, and soldered new wires in the pattern I needed. They work perfectly now.
     
    Last edited: Oct 9, 2009
  8. deusexaethera

    deusexaethera OT Supporter

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    1. I work for a company that thinks all IT expenses should be billed to projects. There literally is no IT budget; everything I do, I have to directly justify as being useful for a specific batch of work we were hired to do for someone.

    2. It's a challenge, and it keeps me occupied.
     
  9. Joe_Cool

    Joe_Cool Never trust a woman or a government. Moderator

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    :rofl:

    FUCK WHY BE EFFICIENT??? RAM AND CPU CYCLES AND CABLES ARE CHEAP!!!
     
  10. deusexaethera

    deusexaethera OT Supporter

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    Reading comprehension isn't a prerequisite to be a mod, huh?
     
  11. Joe_Cool

    Joe_Cool Never trust a woman or a government. Moderator

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    What exactly do you think I didn't comprehend?
     
  12. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    The real problem Deus, is that you didn't simply change the wallplate to a 4 line telephone or 2 line RJ45 wallplate. Instead, you're re-engineering the plug after it's been punched down.
     
  13. mobbarley

    mobbarley Active Member

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    .

    if its only for phone, split the wire into pairs behind the wall and punch them in to the jacks.
     
  14. Hate Crime

    Hate Crime Don't Hate OT Supporter

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    Oh and Deus.. change your fucking username while you are changing those wallplates, your name is terrible
     
  15. deusexaethera

    deusexaethera OT Supporter

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    The building and all the wall- and ceiling-mounted hardware within it, including the cables, is owned by the property management company. We could pay them to run more wiring, but it would cost 5x as much as it would cost to pay me to do it, except that I'm not allowed to do it because it's not our fucking wall. And in any event, running more wiring doesn't address the problem that the wiring standard is FUBAR to begin with.

    I'm working with what I've got here.
     
  16. mobbarley

    mobbarley Active Member

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    so your company is cheap and yet its the "stupid Cat5 wiring standard"s fault? pointless thread.
     
    Last edited: Oct 14, 2009
  17. Stilgar1973

    Stilgar1973 New Member

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    I use a fucking switch in my Father in laws room to EXTEND a cable run. I ran out of cable, it needed to go another 20 feet. I used a switch and another 20 feet of cable.

    I know, simply retarded. I keep looking at it and intending to spend the $3 it would cost to take the switch out.
     

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