8 pin RJ45 (8P8C) female connector at the
network interface cards/hubs.
8 pin RJ45 (8P8C) male connector at the
cables.
100BASE-T4 is an early implementation of Fast Ethernet. It used only two of the four twisted copper pairs and works with category 3 cable.
| Pin | Name | Description | TIA/EIA 568A | TIA/EIA 568B |
|---|---|---|---|---|
| 1 | TX_D1+ | Tranceive Data+ |  white/green |
 white/orange |
| 2 | TX_D1- | Tranceive Data- |  green |
 orange |
| 3 | RX_D2+ | Receive Data+ | white/orange |
white/green |
| 4 | BI_D3+ | Bi-directional Data+ |  blue |
blue |
| 5 | BI_D3- | Bi-directional Data- |  white/blue |
white/blue |
| 6 | RX_D2- | Receive Data- | orange |
green |
| 7 | BI_D4+ | Bi-directional Data+ |  white/brown |
white/brown |
| 8 | BI_D4- | Bi-directional Data- |  brown |
brown |
Notes
- T568A and T568B are the two color codes used for wiring eight-position RJ45 modular plugs. Both are allowed under the ANSI/TIA/EIA wiring standards. The only difference between the two color codes is that the orange and green pairs are interchanged. T568A wiring pattern is recognized as the preferred wiring pattern for this standard because it provides backward compatibility to both one pair and two pair USOC wiring schemes. The T568B standard matches the older ATA&T 258A color code and is/was(?) the most widely used wiring scheme. It is also permitted by the ANSI/TIA/EIA standard, but it provides only a single pair backward compatibility to the USOC wiring scheme. The U.S. Government requires the use of the preferred T568A standard for wiring done under federal contracts.
- One pair is reserved for transmit and one for receive. The other two pair are not used for 100Mbit transmission. They are usually connected for upward compatibility with 1 Gigabit Ethernet.