How many conductors does Ethernet require.

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iwire

iwire

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OK I know Cat 5, Cat 5E, Cat 6 etc all contain 4 pairs (8 conductors) but how many can I make it work with?

I have a situation with a customer that is running a phone on one pair leaving 3 pairs for the PC. Now it appears one pair is open.

Can I make it work on just two pairs?

This is not subject to any testing or certification, all they care about is getting it to work. I suggested wireless but they do not want to go that way.
 
Bob I have never seen ethernet work on less than 4 pair. I am no expert but I have seen many times where one wire was loose and the system would not work.

Obviously running a new wire is not a option so wireless, as you suggested, would be the way to go. Better yet use a wireless phone. They have phones that you plug in a transmitter at a wall jack and picks up a wireless signal for the phone.
 
Dennis Alwon said:
Bob I have never seen ethernet work on less than 4 pair.
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It has been functional on no more then three pairs for at least 5 years. It just stopped working.

When I put a cheap leviton tester on it it indicated I had pairs 1,2 and 3,6 working.


Since I posted this thread I found this

Standards Summary

which seems to indicate that I have enough and the problem is not the cabling.


Obviously running a new wire is not a option so wireless, as you suggested,
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Distance is short, but it would be real tough and cost prohibitive.

Better yet use a wireless phone.
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That is some great thinking but unfortunately it is not a standard phone it is a 'system' phone with many features.


They have phones that you plug in a transmitter at a wall jack and picks up a wireless signal for the phone.
Click to expand...


Hmmm I wonder if that would run the special phone?
 
iwire said:
OK I know Cat 5, Cat 5E, Cat 6 etc all contain 4 pairs (8 conductors) but how many can I make it work with?

I have a situation with a customer that is running a phone on one pair leaving 3 pairs for the PC. Now it appears one pair is open.

Can I make it work on just two pairs?

This is not subject to any testing or certification, all they care about is getting it to work. I suggested wireless but they do not want to go that way.
Click to expand...

Ethernet only requires 4 conductors, I don't remember which ones, but I'll try to find it.

I have done what you want to do before and it will work.
 
roger3829 said:
I found it. Check out this link. You only need Pins #1, 2, 3, 6

http://www.ertyu.org/steven_nikkel/ethernetcables.html
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Thanks, that is what my tester indicated I had. :smile:

A little background, the customers workstation stopped working, they called in their IT contractor and the IT guy figured the cable was bad. He tested the cable but he was on the wrong cable at the patch panel. To be fair he was on the port that was marked for that work station but that was incorrect so of course his test showed an open condition.

Once I put a toner on the work station end I found the correct port at the patch panel. Once I tested that port to the work station I had good continuity on pins 1,2,3,6.

It seems they have another issue. I left a detailed note for the IT that comes back with my cell number so we can talk about it.

I just wanted to make sure two pairs could do it. :smile:
 
roger3829 said:
I found it. Check out this link. You only need Pins #1, 2, 3, 6

http://www.ertyu.org/steven_nikkel/ethernetcables.html
Click to expand...

Correct, but you can get cross talk when using the other pairs for other things.
The faster your network gear, the more prone you are to failure.

You also run the risk of equipment damage if a ethernet pair gets shorted to a non-ethernet pair. Not saying don't do, just beware the pitfalls.
 
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". Many of our cameras and wireless routers at work run on 12VDC and we use one cat5 cable for transmisssion and power supply. I can provide more info on Monday if you are interested.
 
jumper said:
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". Many of our cameras and wireless routers at work run on 12VDC and we use one cat5 cable for transmisssion and power supply. I can provide more info on Monday if you are interested.
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Thank you-- I would appreciate that.
 
Dennis Alwon said:
I learned something new again. Let me ask-- why do we run 8 conductors. Are there ethernet systems that need 8 conductors and some that need 4 or will any system work on 4 conductors. I am a bit confused on this.
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Why run 4 pairs? Because CAT5 cable is only available in 4 pair, it's part of the CAT5 spec. OK, you can get 24-pr CAT5... Don't see it too often.

There -were- some network systems that used all 4 pairs, IIRC100vg did,and I think some of the 10g proposed standards do. Also, it would be a cruel trick to connect something other than all 4 pairs since pretty much everyone expect them to be available.

It has nothing to do with 8-bits-to-the-byte.
 
Check the patch cords with your tester, I had a data guy claim the cable was bad to a terminal on the other side of a store, claimed it was cut, and needed a new one run, well this store was an old Sams Club converted to a Home Depot. With 30' + ceilings, that was not very likely. Looked at the cable they had at the terminal, and it was ragged, replaced the patch cable, terminal worked fine.
 
10Base-T and 100Base-T require 2 pairs -- 1 transmit pair and 1 receive pair. Orange and green are the pairs that are used; as stated earlier, pins 1, 2, 3, & 6.

1000Base-T (or Gigabit ethernet) utilizes all 4 pairs.
 
egnlsn said:
10Base-T and 100Base-T require 2 pairs -- 1 transmit pair and 1 receive pair. Orange and green are the pairs that are used; as stated earlier, pins 1, 2, 3, & 6.

1000Base-T (or Gigabit ethernet) utilizes all 4 pairs.
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All this info is correct.

Just remember, sometimes its the green and orange pair - depending if its 568A or B

~Matt
 
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