Ethernet cable

Inside the ethernet cable, there are 8 color coded wires.
These wires are twisted into 4 pairs of wires.
One wire in the pair is solid colored wire and the other is primarily white wire with a colored stripe.

T568A and T568B are the two color codes used for wiring eight-position RJ45 modular plugs.
Both are allowed under the ANSI/TIA/EIA wiring standards.
The only difference between the two color codes is that the orange and green pairs are interchanged.



Pin Numbering in the clip



Signals on the Pins



In straight cable pin 1 to 8 on one side is connected to pin 1 to 8 on other side

1 <--> 1
2 <--> 2
3 <--> 3
4 <--> 4
5 <--> 5
6 <--> 6
7 <--> 7
8 <--> 8

In Crossover cable Tx is connected to Rx (ie Tx+ to Rx+, Tx- to Rx-, Rx+ to Tx+, Rx- to Tx-)

1 <--> 3
2 <--> 6
3 <--> 1
4 <--> 4
5 <--> 5
6 <--> 2
7 <--> 7
8 <--> 8



In Rolled or rollver cables pin 1 to 8 on one side is connected to pin 8 to 1 on other side

1 <--> 8
2 <--> 7
3 <--> 6
4 <--> 5
5 <--> 4
6 <--> 3
7 <--> 2
8 <--> 1

If same type of devices needs to be connected cross cable is used. ie to connect PC to PC, switch to switch or router to router.

Straight cable is used if both sides of the cables are different types of devices. ie to connect PC to switch or PC to router or switch to router etc.

Gigabit Ethernet ports which support auto sensing (MDI/MDIX) doesn't require cross cable. Straight cable can be used.