How many pairs of wires for data?

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Old 09-27-05, 02:33 PM
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How many pairs of wires for data?

How many pairs of wires (and which ones) are used for data. I was under the assumption that all 4 pair are needed for data, but recently starting seeing references to just 2 pair and 3 pair.

If only need 2 pair, does this mean that with one cat5 cable, I can wire it up for two data lines, or one data line and two voice lines???

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Old 09-27-05, 02:58 PM
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well apple talk ran on a single pair

as to ethernet
10 base-T needs 2 pair (gives 10 mbs throughput , which is fine for internet only as you are likley to be using less then 5 mbs on a good day , )

100 base-T uses all for pair for duplex transmission. at 100 mbs throughput

( I did 10 base-t for a while and it worked fine for internet but bogged down using a shared printer )

not a good idea to run voice on the same cable as the 90vac ring may cause problems
 
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Old 09-27-05, 03:31 PM
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Thanks Mango Man
 
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Old 09-27-05, 06:48 PM
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Originally Posted by mango man
well apple talk ran on a single pair


100 base-T uses all for pair for duplex transmission. at 100 mbs throughput
I have to disagree with this. 100 base-T only uses 2 pair.
 
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Old 09-29-05, 05:53 AM
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Originally Posted by seezar
I have to disagree with this. 100 base-T only uses 2 pair.
actully we are both correct 100base-t can run on either 2 or 4 pairs 1000 baset requires all four pairs .

its still bad practice and non standards compliant to run anything more than one data drop off a single cable .

and I would never run voice and data and the same cable
 
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Old 09-30-05, 06:13 PM
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thats right

I allways just out of habit use all 4. For data allways use all 4 so no one ever trys to bug off others. Cross talk sucks and can happen even in the best panduit professonal install.
 
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Old 10-05-05, 11:33 AM
halosix
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Despite common "myth", only two pairs are used for full-duplex 100BASE-TX ethernet. The gains by using full duplex are gained not by using extra pairs, but by sending and recieving simultaneously instead of waiting for a send or recieve transmission to complete.

For an external reference, here is a link. look about 1/2 way down the page. :
http://www.duxcw.com/digest/Howto/ne...ble/cable5.htm
 
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Old 10-05-05, 03:38 PM
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Most common 10/100 network adapters don't support this full duplex mode, as only two pairs are used (look at a newtork adapter and see). BTW, the org and grn pairs are used for common two pair ethernet.

At that I belive it is not permtted to use the unused pairs in network wiring for voice wiring (at least for outside lines, possibly inside lines as well). I have used the second pair in a network cable for stereo line audio with no ill efects, FWIW.
 
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Old 10-05-05, 05:03 PM
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Originally Posted by classicsat
At that I belive it is not permtted to use the unused pairs in network wiring for voice wiring (at least for outside lines, possibly inside lines as well).
This statement makes no sense. it is unwise to use a piece of Cat 5 for more than one of anything except perhaps phone lines, but there is no prohibition against it.
 
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Old 10-05-05, 05:43 PM
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to run voice and data over the same cable dosnt violate any CODE , so it is not iprofibited per se

it dose however violate 568 ethernet Standards and isnt a good prctice
 
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Old 10-06-05, 05:26 AM
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I never thought I would stir up such a hornets nest with this question.

Anyway, this is just for my own personal use in my home. I have a cat 5 line running to the office and I was wondering if I could use that same cable for both network and phone. Since this is not an office or business setting, I am not too concerned about violating "568 ethernet standard".

On this cat5 cable, I connected all 4 pair to the RJ45 jack. Sounds like I can take one pair and put those onto a regular phone jack (and do the same on the other end of that cable) and I should be in business with both voice and data (as long as I do not use the org and green pair for voice - although this probably depends on what colors are connected where on the other end. I can play around and find which pair of wires I can disconnect)

Does this sound right.
 
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Old 10-06-05, 08:41 AM
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I have enjoyed the discussion , and evan learned from it , far to often on this board there is only one or two replys and it dies .

being aware of the potenial problems , go ahead and try it and if you start seeing issues you can always take the voice off and run a seprate line

for 568a you cab use the orange or brown pair
568 b you can use the green or brown

so it looks like if you use the brown pair for voice you will be ok on either scheme.

post back and let us know how it works out .

as I mentioned ealier I had split , one cable into two connections and when I switched back I saw a noticable increas in print speed .
 
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