Networking: CAT5 Cable Wiring
Pin assignments for twisted-pair Ethernet cabling
Twisted-pair Ethernet (10BASE-T, 100BASE-T, or 1000BASE-T) uses an RJ-45 connector (RJ = Registered Jack), which is an eight-pin modular connector. When looking at the RJ-45 connector on the end of a cable (male) with the tab on the bottom and the contacts on the top, contact 8 is on the left and contact 1 is to the right:
| Contact 1: | (white/orange) | Transmit + |
| Contact 2: | (orange) | Transmit - |
| Contact 3: | (white/green) | Receive + |
| Contact 4: | (white/blue) | Not Used |
| Contact 5: | (blue) | Not Used |
| Contact 6: | (green) | Receive - |
| Contact 7: | (white/brown) | Not Used |
| Contact 8: | (brown) | Not Used |
RJ Plugs 'n' Outlets
When looking at an RJ-45 wall jack or outlet (female), contact 1 is on the left and contact 8 is to the right. The crossover function is accomplished by simply wiring the receive pins to the transmit pins:
Contact 1 -> Contact 3
Contact 2 -> Contact 6
Contact 3 -> Contact 1
Contact 6 -> Contact 2
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Click here for a more detailed pinout diagram, including how to wire up a crossover cable.
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