100BASE-TX Straight-Through
1 TX+ 1 TX+
2 TX– 2 TX–
3 RX+ 3 RX+
4 NC 4 NC
5 NC 5 NC
6 RX– 6 RX-
7 NC 7 NC
8 NC 8 NC
8
1 8
1
Hub/Switch Server/Router
1
wgwb
g o b br
wow br
8
wowb
o g b br
wgw br
1 8
Figure 3-16 Straight-Through Cable
With crossover cables, the RJ-45 connectors on both ends show that some of the wires
on one side of the cable are crossed to a different pin on the other side of the cable.
Specifically, for Ethernet, pin 1 at one RJ-45 end should be connected to pin 3 at the
other end. Pin 2 at one end should be connected to pin 6 at the other end, as shown in
the Figure 3-17 .
Pin Label Pin Label
Some wires on cable ends are crossed.
Cable 10BASE-T/
100BASE-TX Crossover
1 TX+ 1 TX+
2 TX– 2 TX–
3 RX+ 3 RX+
4 NC 4 NC
5 NC 5 NC
6 RX– 6 RX-
7 NC 7 NC
8 NC 8 NC
1
wgwb
g o b br
wow br
8
wowb
o g b br
wgw br
1 8
Crossover Cable
8
1 8
1
Hub/Switch Server/Router
Figure 3-17 Crossover Cable