what is 568 B 2-1 ?

568-B Wiring

Pair # Wire Pin #
1 - White/Blue White/Blue 5
Blue/White 4
2 - White/Orange White/Orange 1
Orange White 2
3 - White/Green White/Green 3
Green/White 6
4 - White/Brown White/Brown 7
Brown/White 8

<< 568-B Diagram

568-A Wiring

Pair # Wire Pin #
1 - White/Blue White/Blue 5
Blue/White 4
2 - White/Green White/Green 1
Green/White 2
3 - White/Orange White/Orange 3
Orange/White 6
4 - White/Brown White/Brown 7
Brown/White 8
<< 568-A Diagram

Notes for wiring diagrams above:

1. For patch cables, 568-B wiring is by far, the most common method.
2. There is no difference in connectivity between 568B and 568A cables. Either wiring should work fine on any system*. (*see notes below)
3. For a straight through cable, wire both ends identical.
4. For a crossover cable, wire one end 568A and the other end 568B.
5. Do not confuse pair numbers with pin numbers. A pair number is used for reference only (eg: 10BaseT Ethernet uses pairs 2 & 3). The pin numbers indicate actual physical locations on the plug and jack.