Cable polarity reversed?

[networknoob]

Hi everyone, I'm trying to hook a computer on a network and the link led on my 3COM ISA ethernet card blinks which on their website says the "cable polarity is reversed". What does this mean? I swapped a cable from another workstation on the network and still doesn't work. I would swap the ethernet card but I don't have a spare ISA ethernet card. Do you think it's the card or the cable? And how do you fix a cable if the polarity is reversed?

 

[ben64]

Wow. I have never heard of cable polarity reversed. But I assume that it means the Orange pair and/or the green pair are backwards. If you already tried another cable, then I suggest that you get another card. That one seems screwy.

 

[wires]

It means that the color wire (green or orange w/white stripe) on one end of the cable is connected to the white wire (white with green or orange stripe) on the other end.

Look at the cable ends and if the same color wires appear on the same pins your card is most likley the problem.

 

[networknoob]

Thank you both for responding. I will check the cable and swap another ethernet card if I find one. Thanks again.

 

[c0i0nes]

On some hubs and Mini-hubs, the port socket that hooks up to a cascading hub has a reverse polarity switch which enables a "cross-over" connection over standard cables.
Is this port connected to a crossed over port on the hub? Can you plug into another port on the hub, or switch over it's polarity?

 

[ben64]

I don't think that is what we are talking about.

I'm thinking pins 1 and 2 and/or pins 3 and 6 are backwards.

meaning - 2 is where 1 should be and/or 6 is where 3 should be.

 

[c0i0nes]

The NIC detects the reversed polarity, rather than just fails, because the detected pattern of received data is on the standard crossover pattern, rather than mixed up voltage polarity. More sophisticated hubs can correct crossed over (data) signals automatically.

Thus: the crossover map is 1Rc+ -> 3Tx+ , 2 Rc- -> 6Tx-,3Tx+ -> 1Rc+, and 6Tx- -> 2Rc-;
Opposed to : Straight Map 1Tx+ -> 1Rc+, 2Tx- -> 2Rc-, 3Rc+ -> 3Tx+, and 6Rc- -> 6Tx-

+ to - connections would fail because they would not pass the diodes which filter out such connection faults, either at the NIC or the Hub ports.

 

[franke]

If you are connecting to your hub via jack and cable and not directly, check the wiring of the jack(s) and/or patch panel.

franke

 

[Bobg1]

franke is correct, this is where these type problems ussually occur.

 

[networknoob]

Hi,

You guys have been very helpful.
The computer is connected to a hub and the hub is then connected to the jack on the wall . The other 2 computers using the same hub are working fine. I will check everything you guys mentioned. Thanks for taking the time to respond.