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Straight-Through Cable Pinout

10BASE-T and 100BASE-T use two pair of wires in a UTP cable, one for each direction, as shown in Figure 2-9. The figure shows four wires, all of which sit inside a single UTP cable that connects a PC and a LAN switch. In this example, the PC on the left transmits using the top pair, and the switch on the right transmits using the bottom pair.


Cover of Cisco CCENT/CCNA ICND1 100-101 Official Cert Guide


PC transmit on 1 and 2; Switch receives on 1 and 2. PC receives in 3 and 6; Switch transmits on 3 and 6.