CAT5 568A v. 568B..Hmmm..odd problem?

Type "A" config is a crossover cable, right? Computer to computer? Type "B" is your standard internet/LAN cable, right? I'm not looking for any major DIY help. I've got the gist except for the part below :-)

Very simply: I wired a LAN RJ45 jack and the instructions said "for residential applications follow the 568A diagram". So the jack(coded for A and B configs on back) is wired as an "A". Now I whip out my crimper to make a cable/plug and look at the back of the crimper package, find the wiring pattern for "A", and make my plug on the end of my cord. THEN I compare mine to some other pre-fab RJ45 wire/plugs and notice that all of the other plugs appear to be wired as "B". Knowing that one of those prefabs I was looking at used to serve as my home internet cable I rewired my "A" plug as a "B" and plugged it in. It worked!

Bottom line: I have an "A" config jack and a "B" config plug and my internet works fine. WHY??? And what should I change? Thanks.

Kevin

Reply to
funkykev
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Kevin,

The difference between 568A & 568B is only the color of the wire pairs at each end. Those specs have nothing to do with a Crossover Cable. Do a Google for Crossover Cable and there are color diagrams on the net "somewhere" that show the proper pairing. Or someone else here may have that at their finger tips.

Good Luck.

Les

Reply to
ABLE_1

A on on end and B on the other is a crossover cable. It works because many modern routers/switches have an auto-sense feature to let either configuration work.

Reply to
Lewis Gardner

Well my first reaction was WHAT?????? Then I googled it and found this.

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And it seems that Lewis is indeed correct. Well I never knew that.................... well if I did I would have then said something like he did. Guess I just never gave the 568A & B enough thought before. You learn something every day. And so it goes.

Thanks Lewis!!!

And now I have re-read the OP and I think I understand what he was questioning. If the BOTH ends of a Patch Cord is configured as a A or a B it does not matter it will work the same.

If a Jack is configured as A on one end it needs to be configured as A on the other end for a Ethernet connection to work, same goes for B. So if you have a Patch Cord at A - A and a Jack that is B - B all works fine. It will not work if you interject a A - B (crossover) into the mix.

If the Patch Cord is configured each end one at A and the other at B it will only work between two PC's.

I hope that makes sense. Sorry I went down a misinformed path earlier.

Les

Reply to
ABLE_1

Having crossover cables around will get you sooner or later.

A much better solution is to make a very short adapter, male on one end, female on the other, wired for crossover. It makes any cable you have into a crossover, and you'll never use it when you didn't mean to.

Isaac

Reply to
isw

On Mar 1, 10:44 am, Lewis Gardner

wrote>

Tah-dah!! Lewis is right. Let's boil off all of the other comments because this is what I was asking in the original post. I've since done some research(and reading here) and am much...er...somewaht wiser. Now I realize how hazy my original description was :-) To be more clear: The jack in question is in the wall. On the back of the jack in the wall I hardwired for the A code/scheme with a CAT5e (no plug, just twisted pairs). The plug at the other end of this cord is wired as a B. I created a crossover cable accidentally. And it's all true: As long as BOTH ends/plugs of any cable are the same, AandA or BandB the cable will function fine with either an A or B wired setup at any given end of it. True? (please confirm). And also apparently my modem is smart enough to know that I have a crossover cable jammed into it and not a straight-thru cable. i will go back and rewire the jack as a B. The exception, I believe, is that if you intend to carry internet or similar AND a Ma Bell phone signal through the same cord, then you need to wire for A at your receptacles? This, however I have not confirmed. There you go. have at it...and thanks!

Kevin

Reply to
funkykev

Oh, one more thing. Some network install guy who apparently runs his own business suggested that there is one config we've discussed that I DONT want because it will result in "packet loss". Conceptually I know what he means, but is it true? I just don't remember if he meant the crossover cable use (in my specific case) or the B cable to the A jack thing. Thoughts? Kevin

Reply to
funkykev

The exception, I believe, is that if you intend to carry

Reply to
BruceR

Yeah - but you're forgetting USOC pinning where the pairs are Line 1 bl/w on pins 4,5 Line 2 o/w on pins 3,6 Line 3 g/w on pins 2,7 Line 4 br/w on pins 1,8

Commonly found on flat (silk) cable with parallel conductors in a sheath. If you want packet loss try this pinning - the data is on split pairs and is effectively unshielded.

Reply to
NewsReader

Trust me, after 35 years in the business I haven't forgotten USOC wiring. 568A & B both keep the bl/w pair on 4&5 and the orange or green pairs, repectively, on 3&6. It's the green or orange pairs, respectively, that get moved to 1&2 and the brown pair that goes to 7&8. So, in either case, you still have USOC wiring for a two line phone available at the jack with the caveat that line two is terminated on the green pair if it's 568B.

Reply to
BruceR

Keep it up and we're going to dust off some 1A2 equipment and make you explain how to wire it up... Or maybe reverse the polarity on your TT keypad to prevent you from making any bulletin board calls... hehehee

Reply to
NewsReader

Both I can do. I cut my teeth on 1A2 to the point where I could punch it down in my sleep. Well, maybe not the ringing diode matrix :) I used to charge $50 to take the shims out of 1A2 keystrips to enable multiline conference calls. There's still a lot of that stuff in use... just take a look at David Letterman's phone! BTW, for those who don't know what USOC means, it stands for Uniform (not 'universal' as some report) Service Order Codes. Every piece of telco equipment or service or wiring configuration had a USOC designation. Even if it was special or "one-off" it was a ZZZxx.

Reply to
BruceR

Kevin,

Thank you for your summary -- an important part of usenet etiquette (" netiquette ").

When folks ask for and receives assistance, it makes the whole exercise much more useful to other folks who may be interested in the answer if the conclusions, recommendations and(or) results are summarized.

Lamentably, this common courtesy is more usually honored in the breach these days.

... Marc Marc_F_Hult

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Reply to
Marc_F_Hult

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