Specifications
C-5
RJ-45 Pinouts and Crossover Function
10BASE-T, 100BASE-TX, and 1000BASE-T are keyed systems to differentiate between voice
and data transmissions, in order to keep them separate over twisted-pair cable. The Ethernet
standard also specifies that each cable segment implement a crossover function to connect the
transmitter of one device to the receiver of a device at the other end, and vice-versa. The
crossover function may be implemented internally at the hub or switch, or externally, through
the twisted-pair media.
10/100 Straight-Through Pinouts
If the crossover function is implemented internally, the port is labeled MDI-X (Medium
Dependent Interface–Crossover). When an MDI-X port is connected to an MDI port, the twisted
pair media should be wired straight-through using the physical pinouts indicated in Table C-9.
Table C-9
10/100 Pinouts Using Internal, Straight-Through Crossover
Pin Function
Color
Match
Function
Pin
1 TD+ White/Orange TD+
1
2 TD- Orange/White TD-
2
3 RD+
White/Green RD+
3
4
Blue/White
4
5
White/Blue
5
6 RD-
Green/White RD-
6
7 White/Brown
7
8 Brown/White
8
Figure C-1 shows straight-through connector wiring to be used when the crossover function is
implemented within the hub or switch.
Figure C-1. 10/100 straight-through wiring for RJ-45 connector
