The RJ-45 Interface.
The RJ-45 (Registered Jack - 45) interface, also known as the "Ethernet" port, or the "Network" port, provides the physical transport layer for connection of a PC to a 10/100BaseT Ethernet network.
The combination of RJ-45 connectors and Cat 5 / Cat 5E cable is an adaptable combination, and as well as being used for data networks, the combination is also used successfully in other applications such as telephone connections, audio and video signals, although clearly, they cannot be used intechangeably.
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RJ-45 Pinouts and functions.
| Pin Number |
10/100baseT Ethernet (IEEE 802.3) |
1000baseT Ethernet (IEEE 802.3) |
PoE Power over Ethernet (IEEE 802.3af Mode B) |
Cat 5/5e Cable Colour Coding |
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| Abbreviation | Function | Abbreviation | Abbreviation | Function | 568A | 568B | |
| 1 | Tx+ | Transmit + | DA + | Tx+ | Transmit + |  |
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| 2 | Tx- | Transmit - | DA - | Tx- | Transmit - |  |
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| 3 | Rx+ | Receive + | DB + | Rx+ | Receive + | |
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| 4 | nc | not connected | DC + | DC + | Power + |  |
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| 5 | nc | not connected | DC - | DC + | Power + |  |
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| 6 | Rx- | Receive - | DB - | Rx- | Receive - | |
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| 7 | nc | not connected | DD + | DC - | Power - |  |
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| 8 | nc | not connected | DD - | DC - | Power - |  |
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See also:
Cat 5 cabling, Cabling information, Ethernet, Network commands / troubleshooting,