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To allow a PC NIC to communicate with a switch, the UTP cable must also use a straight-through cable pinout. The term pinout refers to the wiring of which color wire is placed in each of the eight numbered pin positions in the RJ-45 connector. An Ethernet straight-through cable connects the wire at pin 1 on one end of the cable to pin 1 at the other end of the cable; the wire at pin 2 needs to connect to pin 2 on the other end of the cable; pin 3 on one end connects to pin 3 on the other, and so on. Also, it uses the wires in one wire pair at pins 1 and 2, and another pair at pins 3 and 6.

From

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

Note

NICs and switches work. As a rule, Ethernet NIC transmitters use the pair connected to pins 1 and 2; the NIC receivers use a pair of wires at pin positions 3 and 6. LAN switches, knowing those facts about what Ethernet NICs do, do the opposite: Their receivers use the wire pair at pins 1 and 2, and their transmitters use the wire pair at pins 3 and 6. 1 and 2 use Orange /Orange-White and 3 and 6 use Green/Green-White.