HP NC3131 Fast Ethernet Server Adapter - Manual (Page 28)

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