Questions

When wall wiring acts like a good cross over and a bad straight

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When wall wiring acts like a good cross over and a bad straight

I just ran about 30 ft. of CAT5e from one room in my house to another since I've moved two of our three computers to make room for a new baby.

Each end of the long wire is terminated by a rj45 port. I've re-checked and rewired it several times to make sure that each port is wired exactly the same (i.e. same color wire is hooked to position #1 on each port, etc.)

However, this does not work as expected. I'm getting anywhere from 20-100% packet loss when connecting a computer in room 2 with the router in room 1 (computer->patch cable->wall wiring->patch cable->router). However, when I connect a computer in room 2 to one in room 1 (computer->patch cable->wall wiring->patch cable->computer), the connection is great.

I have checked the patch cables to make sure that none are crossovers (which doesn't make sense since I've used them all previously to connect the computers directly to the router).

Any ideas?

Thanks!
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    OH Smeg

    Are you sure that both RJ45 Sockets are from the same maker?

    Quite often different makers have different ways of wiring their sockets or at least the connectors on the back do not go to the same pin of the socket. You really need a Cable Tester to check the lead.

    You can pickup a $20.00 one on E Bay and use this to correctly setup the wiring of the cable.

    Col

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    ozi Eagle

    Hi

    Further to what Col said, above, there are two standards for Cat5 wiring, T568a and T568b. For a straight through connection both ends need to be to the same standard ( it doesn't matter which one as long as both ends are the same). As it happens if you mix the end standards you do get a crossover cable. Follow up on Col's suggestion of getting two sockets from the same maker, so that their color coding is to the same standard.

    Herb

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    Both are from the same manufacturer.

    However, as the quality of the sockets is somewhat questionable, I might replace them if no other solution presents itself.

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    mjd420nova

    Iy is possible that you've gotten the cable a little too close to some power wiring in the wall. This can cause all sorts of problems especially when neither end is grounded.

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    0 Votes

    There is one point in the wiring that brings the cable in very close proximity with two power wires, so interference does make sense.

    However, if the problem was interference, why am I getting perfect communication computer-to-computer?

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    kiran.maan

    Try cover it in flexi pipe to avoid any power wire disturbance.

    Is that packet is lost all time or specific ?

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    OH Smeg

    To see if you get communication?

    It really sounds as if the Cable isn't correctly wired to the sockets.

    I also keep any CAT Cable at least 12 inches away fro Electrical Wiring and more if it is the High Voltage type Wiring for 3 Phase Power Points and so on. In the US Finances or House heaters tend to draw a lot of power and you need to keep the CAT Cable further away from this.

    Col

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    1bn0

    You state "(i.e. same color wire is hooked to position #1 on each port, etc.)"

    The pairs must be matched for proper transmission
    Pins 1&2
    Pins 3&6
    Pins 5&4 (they reverse for this pair)
    Pins 7&8

    each pair should be a matched wire set.

    WhiteOrange/Orange(White)
    WhiteGreen/Green(White)
    WhiteBlue/Blue(White)
    WhiteBrown/Brown(White)

    Yes it matters.

    http://www.n-tron.com/pdf/Cat5eCableSchemes.pdf

    http://www.swhowto.com/CAT5_Ch1.htm

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    0 Votes
    ozi Eagle

    Hi,

    Note that the pairs do not terminate on adjacent pins. The n-tron reference about gives the correct pin connections.

    With the cable entry end facing towards you and the locating tab down with pin 1 at the left, these are the pin connections .

    Pin Color
    T568A standard

    1 Green/White
    2 Green
    3 Orange/White
    4 Blue
    5 Blue/White
    6 Orange
    7 Brown/White
    8 Brown


    T568B standard

    Pin Color
    T568A standard

    1 Orange/White
    2 Orange
    3 Green/White
    4 Blue
    5 Blue/White
    6 Green
    7 Brown/White
    8 Brown

    NOTE, only the Green and Orange pairs are actually used, the Brown and Blue do nothing.

    Sometimes it is possible to utilise these two unused pairs to connect a second computer, however, be aware that crossover may occur and therefore only use one computer at a time.

    Herb

    Edited to remove duplication

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    0 Votes

    Before I say what the real problem ended up being, let me say that I did double and triple check the wiring initially.

    So...to verify that the cable was good and the being run right next to some electric cables wasn't causing issues (it wasn't) I tore off the ports and put plugs on each end. The cable worked great.

    Then I rewired the ports (again). Lo and behold, it works fine now. My guess is that originally I mistook the white/brown wire for the white/orange wire or something like that.

    Thanks everyone for their help!

  • +
    0 Votes
    OH Smeg

    Are you sure that both RJ45 Sockets are from the same maker?

    Quite often different makers have different ways of wiring their sockets or at least the connectors on the back do not go to the same pin of the socket. You really need a Cable Tester to check the lead.

    You can pickup a $20.00 one on E Bay and use this to correctly setup the wiring of the cable.

    Col

    +
    0 Votes
    ozi Eagle

    Hi

    Further to what Col said, above, there are two standards for Cat5 wiring, T568a and T568b. For a straight through connection both ends need to be to the same standard ( it doesn't matter which one as long as both ends are the same). As it happens if you mix the end standards you do get a crossover cable. Follow up on Col's suggestion of getting two sockets from the same maker, so that their color coding is to the same standard.

    Herb

    +
    0 Votes

    Both are from the same manufacturer.

    However, as the quality of the sockets is somewhat questionable, I might replace them if no other solution presents itself.

    +
    0 Votes
    mjd420nova

    Iy is possible that you've gotten the cable a little too close to some power wiring in the wall. This can cause all sorts of problems especially when neither end is grounded.

    +
    0 Votes

    There is one point in the wiring that brings the cable in very close proximity with two power wires, so interference does make sense.

    However, if the problem was interference, why am I getting perfect communication computer-to-computer?

    +
    0 Votes
    kiran.maan

    Try cover it in flexi pipe to avoid any power wire disturbance.

    Is that packet is lost all time or specific ?

    +
    0 Votes
    OH Smeg

    To see if you get communication?

    It really sounds as if the Cable isn't correctly wired to the sockets.

    I also keep any CAT Cable at least 12 inches away fro Electrical Wiring and more if it is the High Voltage type Wiring for 3 Phase Power Points and so on. In the US Finances or House heaters tend to draw a lot of power and you need to keep the CAT Cable further away from this.

    Col

    +
    0 Votes
    1bn0

    You state "(i.e. same color wire is hooked to position #1 on each port, etc.)"

    The pairs must be matched for proper transmission
    Pins 1&2
    Pins 3&6
    Pins 5&4 (they reverse for this pair)
    Pins 7&8

    each pair should be a matched wire set.

    WhiteOrange/Orange(White)
    WhiteGreen/Green(White)
    WhiteBlue/Blue(White)
    WhiteBrown/Brown(White)

    Yes it matters.

    http://www.n-tron.com/pdf/Cat5eCableSchemes.pdf

    http://www.swhowto.com/CAT5_Ch1.htm

    +
    0 Votes
    ozi Eagle

    Hi,

    Note that the pairs do not terminate on adjacent pins. The n-tron reference about gives the correct pin connections.

    With the cable entry end facing towards you and the locating tab down with pin 1 at the left, these are the pin connections .

    Pin Color
    T568A standard

    1 Green/White
    2 Green
    3 Orange/White
    4 Blue
    5 Blue/White
    6 Orange
    7 Brown/White
    8 Brown


    T568B standard

    Pin Color
    T568A standard

    1 Orange/White
    2 Orange
    3 Green/White
    4 Blue
    5 Blue/White
    6 Green
    7 Brown/White
    8 Brown

    NOTE, only the Green and Orange pairs are actually used, the Brown and Blue do nothing.

    Sometimes it is possible to utilise these two unused pairs to connect a second computer, however, be aware that crossover may occur and therefore only use one computer at a time.

    Herb

    Edited to remove duplication

    +
    0 Votes

    Before I say what the real problem ended up being, let me say that I did double and triple check the wiring initially.

    So...to verify that the cable was good and the being run right next to some electric cables wasn't causing issues (it wasn't) I tore off the ports and put plugs on each end. The cable worked great.

    Then I rewired the ports (again). Lo and behold, it works fine now. My guess is that originally I mistook the white/brown wire for the white/orange wire or something like that.

    Thanks everyone for their help!