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5.2 10BASE-T Components

10BASE-T Crossover Wiring

When connecting two twisted-pair MAUs together over a segment, the transmit data pins of one eight-pin connector must be wired to the receive data pins of the other, and vice versa. The crossover wiring may be accomplished in two ways: with a special cable or inside the hub.

For a single segment connecting only two computers you can provide the signal crossover by building a special crossover cable, with the transmit pins on the eight-pin plug at one end of the cable wired to the receive data pins on the eight-pin plug at the other end of the crossover cable and vice versa.

FIGURE 5.2 10BASE-T crossover cable

However, when you are wiring multiple segments in a building it's much easier to wire the cable connectors "straight through," and not worry about whether the wires in the jumper cables or other twisted-pair cables in your building have been correctly crossed over. The way to accomplish this is to do all the crossover wiring at one point in the system: inside the multiport hub.

The standard recommends that the signal crossover be done internally in each hub port. If the crossover function is done inside a hub port, then the standard notes that the port should be marked with an "X."

Quick Reference Guide to 10BASE-T Twisted-Pair Ethernet - 04 SEP 95
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