C-2
Compaq NC3123 Fast Ethernet Server Adapter User Guide
UTP Cable Specifications
To connect to the network, the NC3123 adapter uses the following cable.
10BASE-T
Category 3 or better UTP twisted-pair
22-26 AWG, 100
Ω
at 1MHz
EIA/TIA 568a or EIA/TIA 568b
100BASE-T
Category 5 or better UTP twisted pair
22-26 AWG, 100
Ω
at 1MHz
EIA/TIA 568a or EIA/TIA 568b
RJ-45 Pinouts and Crossover Function
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-2.
Table C-2
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
