Utp cable specifications, 10base-t, 100base-t – HP NC3120 Fast Ethernet Server Adapter User Manual

Page 19: Rj-45 pinouts and crossover function, 10/100 straight-through pinouts

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C-2 Compaq NC3120 Fast Ethernet Server Adapter User Guide

UTP Cable Specifications

To connect to the network, the NC3120 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 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

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