100Base-T4 uses all four pairs. 100Base-TX only uses two pairs.

 (at the network interface cards/hubs)
 (at the cables)

RJ45 FEMALE CONNECTOR at the network interface cards/hubs.
RJ45 MALE CONNECTOR at the cables.

Note: TX & RX are swapped on Hub"s. Don"t know about Bi-directional data.

This cable can be used to cascade hubs, or for connecting two Ethernet stations back-to-back without a hub. It works with 10Base-T, 100Base-TX, 100Base-T4 and 1000Base-T. Use a good enough cable, if you are confused about categories of cables then use category 5e(nhanced) and you"ll be fine even at 1000Base-T.

 (To network interface card 1).
 (To network interface card 2).

RJ45 MALE CONNECTOR to network interface card 1.
RJ45 MALE CONNECTOR to network interface card 2.

(1000Base-T names in parentheses)

That means that the white/orange cable connected to NIC 1 pin 1 should go to NIC 2 pin 3 and NIC 1 pin 2 to NIC 2 pin 6 etc.

Note 1: It"s important that each pair is kept as a pair. TX+ & TX- must be in the pair, and RX+ & RX- must together in another pair. (Just as the table above shows).

Note 2: While 10Base-T and 100Base-TX only uses 2 pairs, please connect all four since 100Base-T4 and 1000Base-T needs them and save yourself some future debugging :)

Note 3: The colors originate from the numbering and name on NIC1.