Compaq 3134 manual RJ-45 Pinouts and Crossover Function, 10/100 Straight-Through Pinouts

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