Cable ends: how important is standard?

James Knott wrote: (snip)

That is self inductance.

That is mutual inductance.

-- glen

Are either of these the preferred or more up-to-date standard, or are they interchangable.

Also, do any of you guys have tricks (ala Roy G. Biv for the colors of the rainbow) to remembering this? I suppose it's not hard if you do dozens a week, but if you are doing only a few a year it would be helpful.

Thanks.

As long as you make both ends the same, they are functionally equal. [1] That said, 95% of the folks use 568B; except some USG contracts still call for 568A.

Every jack I have seen in years has the color code on the label; usually the only confusion is me getting out my reading glasses to read it.

If you are punching down PLUGS, you need to be "dope-slapped" {in the words of Click & Clack} as you can buy patch cables cheaper than make them....and get a better cable.

That said: note that the lay alternates COLOR WHITE COLOR WHITE etc.

[1] Well, almost... since the twists are different rates, the pairs are different lengths. This is of zero interest since the difference is so small, EXCEPT to the standards folks working on the latest NTP protocol. Seems that there, the few nanoseconds of difference DOES matter.

The residential std now calls for -A to get USOC compatibility for pair one (blue) _and_ pair two (orange).

_FULLY AGREED_. If you don't know what a split pair is, nor why it's bad, then you've got no business with crimpers.

Are you _trying_ to be mean? :) The most common error (in-order pairs crimped) is also perfectly alternating. The big problem with crimping is it is counter-intuitive.

Always presuming no split pairs!

-- Robert

Sigh; WTH cares if you use OR or GN as the 2nd pair...

True, but it's also he case if you DO follow the rules.

Ma Bell! Go wash your mouth out with soap! :)

-- Robert

I'm glad this has led to some interesting and informative discussions.

I rewired the connectors according to 568B and then my 50-meter cable worked fine. Splitting pairs definitely does lead to failure on longer cables!

Friend of mine and I were doing this lil' home network and our deal was that I'd do the computer configs if he did the cables. He'd never done network connectors, though, just telephone connectors (which is more than I'd ever done), and he'd assumed that straight thru would be fine :). What was confusing was that the short cables he did for practice worked OK and the cheap network cable tester confirmed the current on each pin. So then owing to the help received here and at alt.comp.hardware, I found out about the standards etc. and the rest is history.

Well, now I also know that there's lots I'd rather be doing than fixing connectors. Fortunately I won't be doing them often--if ever again!

Wanna thank everyone for the help. Nice group here.

Many years ago, I used to work on a system that used triaxial cable, which had two separate shields. This was used on the one of the earliest computer networks (Collins computers). That network dates back to the mid

60s and used time slots, rather than the packets that are common today. All the devices, such as tape and disk drives, were connected on a ring, which ran at 8 Mb/s. The network consisted of two rings and devices could be attached to either ring, under program or manual control. When a device wanted to transmit, it was assigned a time slot, which the receiving device was told to listen to.

Agreed. Coaxial is unbalanced (lets ignore twinax, which has two central conductors). However, coaxial cable is SCREENED. That is how you can get away with a length of unbalanced cable/signal not picking up everything in the neighbourhood. - Its down to the screen. Even then, it is not always that successful. Phil Partridge snipped-for-privacy@pebbleGRIT.demon.co.uk Remove the grit to reply

If you terminate the jacks B and the phone guy comes out and adds a 2nd line, he's going to hook up the orange pair. Then somebody's gonna care.

CIAO!

Ed

David Lesher wrote:

It is the approximate length I have read here when people say that a cable doesn't work, then divided by 10 and 100.

Or, about 1/10 the wavelength for 10baseT, and then 1/10 and 1/100 of that. About the same either way.

While the frequency doesn't go up by a factor of 10, the faster standards are a little more sensitive, so I use a factor of 10, anyway. If you get to where the difference between 20cm, 30cm, and 40cm makes a big difference, you can measure them yourself.

-- glen

I've noticed that the last several hundred patch cables we've received have all been Cat6 (said on the bag), with the special two-part plugs and the weird cable that doesn't say anything about what category it is (says 4/23, tho). These have been both systimax and another brand made in thailand. To do these yourself seems like it's masochistic, since the whole plug is different and needs new supplies and crimpers, etc. Probably new, more precise technique, too.

We're getting ready to move into our new 90,000 sq ft bldg, with over

600 drops all Cat6, with all Systimax supplies. Looks like I gotta get the boss to let me order a bunch of cat6 Systimax stuff. ;-) Everything I've done up to now has all been cat5e. I read that the Crisco gear will cost over $200K just for this site. And they have the nerve to complain about me spending a few bucks for tools.

Everything's running late, no carpet on the floors yet, still a lot of finish work to be done. No labels on the jacks yet(!) I don't know if I'll be asked to work over the xmas vacation. Bummer. Damn contractors!

(snip)

Buy them on eBay, and they can be cheaper than the connectors for do it yourself cables. I have bought them for school networking projects, 100 cables for about $30.

For unusual lengths, though, it is still useful to make my own.

For a round trip connection the total time will be the same either way. For a patch cable (2m or so) the difference should be less than 1ns. For a longer cable it could be a few. You don't have that much control over the rest of the network, though.

-- glen