How many conductors does Ethernet require.

[Rockyd]

Jumper,

Please do post. I normally only get to the page periodically, but would be really interested in some beneficial reading as to what is really required.

 

[jim dungar]

I believe it has to something to do with parallel transmission. 8 wires equals 8 bits ot transmision, or a "byte" at a time. 4 wires equals 4 bits, a "nibble".

You are correct for parallel communications, but Ethernet TCP/IP is serial.

Technically only 2 conductors are required for Ethernet, but the common Ethernet TCP/IP uses 4 conductors.

Ethernet is color blind. It does not care what colors the conductors are; only which pins they are connected to.

Very briefly and not technical:
Even today, most Ethernet communications (end connections to laptop and desktop PCs) involve speeds in the 10M class. Because it is 'slow', this speed is very noise tolerant, so pair twisting is not an issue and actually only requires Cat 3 cabling. Connections to routers and switches and most servers involve speeds in the 100M class. This speed requires a more controlled twisting of the conductor pairs so Cat 5, and its enhancements, cable was created. The pairs of conductors in these cables have a different number of twists, so placing the correct color conductor on the correct pin will allow the most performance out of the system Devices that push lots of data, really fast, like real live server rooms need speeds in the 1G+ range. Here the geometry of the conductor pair spacing as well their twists is very critical as is color conductor to pin matching and the length of 'untwisted' conductors.

 

[wireguru]

when youre wiring it up, make sure you dont get a 'split pair' where tx+/- and rx+/- arent on their respective twisted pairs. For example, 10/100 ethernet uses the green and orange pairs. If you put the white/brown where the white/orange is supposed to be, it will not work. You will get continuity and most cheaper cable testers will pass it, but you will have terrible problems.

 

[LV grider]

I do it every day

I do it every day

This is actually very simple to do. You use 2 of the 4 pairs for data and 1 of the remaining pair for the phone.

Too bad you treated me like dirt in previous posts. We coulda worked together and you coulda billed for like you were a professional. Good Luck

 

[iwire]

This is actually very simple to do. You use 2 of the 4 pairs for data and 1 of the remaining pair for the phone.

That is what they had working for a long time, then it stopped working and the IT contractor said the cable was bad and must be changed. I maintained it was not a bad cable.

But I was there today with an apprentice and we ran two new cat 5E cables, one used for phone and one for data.

It still does not work, looks like the IT guy will have to find another reason.

Too bad you treated me like dirt in previous posts. We coulda worked together and you coulda billed for like you were a professional. Good Luck

Yeah, too bad.

 

[LV grider]

Welcome to my world

Welcome to my world

:smile: Since it worked previously and the just suddenly quit then it is a shame the computer guy sent you off on the hunt for a cable fault. Even though using 2 pair for data and 1 pair for voice will work it is still considered rigging and not recommended.

If you find out later the problem to be a network card I like to know.

 

[jumper]

:smile: Since it worked previously and the just suddenly quit then it is a shame the computer guy sent you off on the hunt for a cable fault. Even though using 2 pair for data and 1 pair for voice will work it is still considered rigging and not recommended.

If you find out later the problem to be a network card I like to know.

Could you explain the rigging and why it is not recommended? why would POE be different than using extra pairs for phone?

 

[jumper]

Too bad you treated me like dirt in previous posts.

I am have a hard time believing this statement, the big guy is opinionated and stubborn, but who isn't, I have not found any statements he has made to cruel or demeaning. You are going to have a hard time making me believe this statement. Can you elaborate this statement with proof?

 

[iwire]

Even though using 2 pair for data and 1 pair for voice will work it is still considered rigging and not recommended.

Yeah, I wish I grabbed some pictures of the way they broke out the phone at each end. Looked like something a homeowner would have done.

But this customer had replaced a register with a service desk in many of their stores and they needed a phone at the service desk so they did what they had to do. Real tough area to get lines into, it took 13 man-hours to run the two lines.

 

[Dennis Alwon]

Real tough area to get lines into, it took 13 man-hours to run the two lines.

That's probably because you did it legally and neatly. or were you just watching?

 

[iwire]

That's probably because you did it legally and neatly. or were you just watching?

It looked good and yes I am working.:smile:

 

[hillbilly1]

I had the IT people say that a brand new cable that I had run for a register was bad, (Two pair sheilded, Fujitsu register system) They had terminated the jacks (kinda like a microphone jack, if I remember correctly they were called "Cannon Jacks") and when I ohmed it out one wire was shorted to sheild. Took apart the jack, and saw the worst soldering job ever! Re-did both ends and pluged it in, and it worked. Sent a bill to Fujitsu for having to come back out.

 

[LV grider]

Rigging

Rigging

iwire wasn't actually rude he just locked a thread a while back cause there was too much macho going on.

Anyway, back on topic. The right way to make a network connection is using all 8 conductors. Only 4 will be used. It is possible to separate out 1 pair to run a phone but not recommended since only a professional would be able to recognize and deal with this config in the future. If a problem comes up then every Tom, Dick & Harry will try to fix it before a pro gets involved. This is a hidden liability you won't experience with high voltage work since it has a habit of identifying indivials on the spot.

Get my drift?

 

[iwire]

The job that will not die.

The job that will not die.

Well after running two new Cat 5E cables, one for the phone and one for the data both ends punched down B and my tester confirmed that my office got a message that we have to go back and "punch it down straight through".

My guess is that the IT contractor has a crossover cable on his tester. At this point I was fed up and asked the office to send one of our data com guys out to check my work.

He is taking a wire scope with him and will generate a report. I should hear from him later today. For better or worse I will let you know. :smile:

 

[gar]

090327-2012EST

Bob:

What does this mean?

Well after running two new Cat 5E cables, one for the phone and one for the data both ends punched down B and my tester confirmed that my office got a message that we have to go back and "punch it down straight through".

If both ends are terminated T-568A, the cable is straight thru.
If both ends are terminated T-568B, the cable is straight thru.

If one end is T-568A and the other end is T-568B, then it is a crossover cable.

So if what your comment meant was that both of your ends are T-568B, then you already have a straight thru cable.

I have photos of both of these terminations at P1 and P2 on my web site at
http://beta-a2.com/rj45_cable_assembly.html

.

 

[iwire]

If both ends are terminated T-568A, the cable is straight thru.
If both ends are terminated T-568B, the cable is straight thru.

If one end is T-568A and the other end is T-568B, then it is a crossover cable.

Both ends are terminated B, that was why I was surprised when I got a message to go back and make it that way.

I suspect the person testing has a cross over cable on their tester.

 

[iwire]

Well I got an email from our Telcom guy, he says it tested fine.

 

[GeorgeB]

Could you explain the rigging and why it is not recommended? why would POE be different than using extra pairs for phone?

There is no switching with the DC power; phones (POTS) have upwards of 100VAC ringing which couples into the data wiring. The phone DC ("battery" of about 48V) and talking AC (POTS) didn't bother it in the applications I saw. My oscilloscope on the Ethernet lines showed nothing when the phone answered, but did show the ringing signal crosstalk.

Acronyms ... POTS is Plain Old Telephone Service or something similar. The newer phone systems that digitally transfer data would likely cause no problems.

At one time, when the standard 4 pair CAT5 was run and another Ethernet drop was needed (this was in the "old" 10BaseT era), you could buy an adapter for each jack which looked like a "wye". It used 2 pairs for one circuit and 2 for another. Only a dozen or so in my personal knowledge realm ... but the folks using them had no trouble.

 

[danickstr]

I will second the case against running POTS and TCP/IP on the same cable. Even though it can be done (if you rig it) it is a potential source of problems.

While only 2 pairs are used for TCP/IP, they are very sensitive to the fat voltage impedance from a ringing phone, which as most of us know, will make you jump if you are holding them leads and the phone rings

But you will not improve the speed of TCP/IP to my knowledge by connecting the unused pairs, although some may consider it good practice to do, in the event of future spec changes, or to use pair one (4-5) if they decide to change the cable to POTS. But hooking up 7-8 is almost always just extra work.

 

[dbuckley]

If the world of offices, running phone and data down one cable is very common, mainly because those who pay for the flood wiring are too mean and can't see the benefit of paying for four Cat5 sockets per desk.

The adapters necessary to make one Cat5 do data and phone are vrey commonplace, and cause no operational problems.