Question:
I want to connect two office computers together temporarily via Ethernet 10BaseT without a concentrator. I believe I use the 1, 2, 3 and 6 wires in an eight-wire TP cable. If this is correct, what are the pin assignments in the alternate RJ-45 ends?
Answer:
For 10BaseT Ethernet, the pin-outs are as follows:
At the network interface card of NIC:
| 1: | Transmit + |
| 2: | Transmit – |
| 3: | Receive + |
| 4: | not used |
| 5: | not used |
| 6: | Receive – |
| 7: | not used |
| 8: | not used |
If you connect via a hub, please note that the pin-outs at the hub are as follows (the Tx+ goes to the Rx+, the Tx- goes to Rx-, and vice-versa):
| 1: | Receive + |
| 2: | Receive – |
| 3: | Transmit + |
| 4: | not used |
| 5: | not used |
| 6: | Transmit – |
| 7: | not used |
| 8: | not used |
On the other hand, if you choose to connect two NICs, construct a cable to connect the Tx+ from one end to the Rx + at the other, Tx- from one end to Rx – at the other, and vice-versa. Therefore, the cable end connecting to the second NIC without a hub would appear as follows:
Pin 1 should go to Pin 3
Pin 2 should go to Pin 6
Pin 3 should go to Pin 1
Pin 6 should go to Pin 2
