Question about Ethernet Cables

[Josh1986]

I know that it only takes 4 wires to complete a ethernet connection. Since an ethernet end has 8 pins, why are they not used.

 

[DaMadScientist]

i believe its only to make the guidance of the wires into the jacks a bit easier

 

[Sodaen]

It depends. 10/100 megabit and 1000megabit Ethernet (sorry I said DSL earlier) differ. 10/100 has 2 for transmitting data, 2 for receiving data. 1000 megabit uses all 8 and all of which are bidirectional, capable of transmitting and receiving.

 

[Ethereal_Dragon]

No, sorry.... 10/100/1000 is going to be the same if you are talking Ethernet. It uses pairs 1,2,3 and 6. The pairs that are not used are there to prevent cross-talk. It has also to do with the way the wires are twisted around one another inside of the sheathing.

Some devices, like higher end Enterprise equipment use them for POE, Power over Ethernet. An example would be a CISCO wireless access point that can be powere via POE, and not need AC power.

Different networking standards use different pairs inside of the cables.... Etherenet and Token Ring, T1's, and 56/64k (not your home dialup) circuits use different pinouts.

 

[forest]

also the 2 middle wires on the cable (both blue wires) cane be used for telephony this is how some colleges set it up so they only need to run 1 wire to each room for internet and phone.

 

[daddy_ray]

ya some wires are for ethernet signal and typically some are used for power. I believe the Oranges and the greens are signal. Pins 1,2,3,6. And the Blues and browns are power. Pins 4,5,7,8. This is how a standard straight thru POE cable would be connectorized. Forest is right on, Some people will run one wire to a room split that wire so you can get ethernet signal from 4 wires and use two others for phone and the other two will just be wrapped with tape and stuffed aside.