Network Wiring: A or B?

Question

I've just realized that I've got my wiring standards mixed up. All my jacks are punched down as "A," while all the plugs and patch cables and the patch panel in the closet are "B."

Everything works perfectly. I've made this mistake in my house, my mom's house, her boyfriend's house, and two other houses now (I got bad info from an installer friend.)

However, everything works, everywhere, with every computer that's been plugged in to them.

Are routers and network cards smart enough to figure this out? The difference in standards is that Tx and Rx (both + and -) have switched places -- right?

Pat Farrell · Accepted Answer

It really makes no difference. Except on a single cable. The signal does not know what color the wire is. So it is pin 3 to pin 3, etc.

At least for normal 10 and 100 base T setups. Maybe at giga rates. it could change which signals go down which pairs, which might make it more susceptible to interference.

E. Lee Dickinson · Answer

Which would make sense if I had wired BOTH ends wrong. But as I said: One end (wall plates) is punched down "A."  The other end, male plugs right in to my switch, is wired "B."

E. Lee Dickinson · Answer

To satiate my curiosity, I just changed ONE end of the cable from "A" to "B."  As you can see, I am online. No problem.So which piece of gear is deciding between TX and RX?

Lewis Gardner · Answer

So all your in the wall wiring is wired as a two pair crossover cable.

I would re-terminate one end to make all the in-wall wiring either A or B. Most modern equipment will auto switch to take care of this problem but it is better to do it right.

Don't worry about the occasional patch cable that is A when you wired everything else A. As long as all of your cables are straight through (pin 1 to pin 1) everything will be fine.

Lewis Gardner · Answer

Whoops!!!Don't worry about the occasional patch cable that is A when you wired everything else B.Most likely a router or switch is "fixing" the problem.

Network Wiring: A or B?

Join the Discussion

Didn't find your answer?