Ethernet: 10/100/1000Base-T Ethernet Port Pinouts
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An Ethernet port uses an RJ-45 connector. It is typically located on the back or side of the computer. Table 1 shows the signals and pin assignments for 10Base-T and 100Base-T. Table 2 shows the signals and pin assignments for 1000Base-T, otherwise known as gigabit Ethernet.
Table 1 Signals for 10Base-T and 100Base-T
| Pin | Signal name | Signal definition |
| 1 | TXP | Transmit (positive lead) |
| 2 | TXN | Transmit (negative lead) |
| 3 | RXP | Receive (positive lead) |
| 4 | Â | Not used |
| 5 | Â | Not used |
| 6 | RXN | Receive (negative lead) |
| 7 | Â | Not used |
| 8 | Â | Not used |
Table 2 Signals for 1000Base-T
| Pin | Signal name | Signal definition |
| 1 | TRD+(0) | Transmit and receive data 0 (positive lead) |
| 2 | TRDÂ(0) | Transmit and receive data 0 (negative lead) |
| 3 | TRD+(1) | Transmit and receive data 1 (positive lead) |
| 4 | TRD+(2) | Transmit and receive data 2 (positive lead) |
| 5 | TRDÂ(2) | Transmit and receive data 2 (negative lead) |
| 6 | TRDÂ(1) | Transmit and receive data 1 (negative lead) |
| 7 | TRD+(3) | Transmit and receive data 3 (positive lead) |
| 8 | TRDÂ(3) | Transmit and receive data 3 (negative lead) |
Gigabit Ethernet is a standard developed by the Gigabit Ethernet Alliance, and defined by the IEEE 802.3 committee. The aim of this standard is to utilize existing local area network infrastructure to achieve up to 1 gigabit per second (1 Gbps) transfer rates. This is why gigabit Ethernet utilizes Category 5 or better unshielded twisted pair cabling (UTP), and the RJ-45 connector that is used in 10/100 megabits per second (Mbps) networks. To achieve maximum transfer rates from gigabit Ethernet capable hardware, you also need to install gigabit Ethernet compliant switches, hubs, and routers. Otherwise, the computer switches to a 10 Mbps or 100 Mbps transfer rate depending upon the network hardware that is used.
To utilize gigabit Ethernet, you must use an Ethernet cable with all eight wires (four pairs) present. If you use an inexpensive two pairs-wired cable, the maximum connection speed can only be 100 Mbps.
The Ethernet interface conforms to the ISO/IEC 802.3 specification, where applicable, and complies with IEEE specifications 802.3i (10Base-T), 802.3u-1995 (100Base-T), and 802.3ab (1000Base-T).