Wiring
Connectors are frequently terminated using the T568A or T568B pin/pair assignments that are defined in TIA/EIA-568-B. The drawings to the right show that the copper connections and pairing are the same, the only difference is that the orange and green pairs (colors) are swapped. A cable that is wired as T568A at one end and T568B at the other (Tx and Rx pairs reversed) is a "crossover" cable. Before the widespread acceptance of auto-MDI/MDIX capabilities a crossover cable was needed to interconnect similar network equipment (such as hubs to hubs). A cable wired the same at both ends is called a "patch" or "straight-through" cable, because no pin/pair assignments are swapped. Crossover cables are sometimes still used today to connect two computers together without a switch or hub, however most Network Interface Cards (NIC) in use today are called smart, because they automatically configure themselves based on the type of cable plugged into them. If a "patch" or "straight" cable is used to connect two computers with "smart" NICs, the NIC will configure itself to switch the Tx and Rx.

Pin	T568A Pair	T568B Pair	1000BASE-T Signal ID	Wire	T568A Color	T568B Color	Pins on plug face (socket is reversed)
1	3	2	DA+	tip	white/green stripe	white/orange stripe
2	3	2	DA-	ring	green solid	orange solid
3	2	3	DB+	tip	white/orange stripe	white/green stripe
4	1	1	DC+	ring	blue solid	blue solid
5	1	1	DC-	tip	white/blue stripe	white/blue stripe
6	2	3	DB-	ring	orange solid	green solid
7	4	4	DD+	tip	white/brown stripe	white/brown stripe
8	4	4	DD-	ring	brown solid	brown solid

Note that the only difference between T568A and T568B is that pairs 2 and 3 (orange and green) are swapped. Both configurations wire the pins "straight through", i.e., pins 1 through 8 on one end are connected to pins 1 through 8 on the other end. Also, the same sets of pins connect to the opposite ends that are paired in both configurations: pins 1 and 2 form a pair, as do 3 and 6, 4 and 5, and 7 and 8.

Even you are using Cat 5 cable with 4 twisted pair wires, it doesn't mean that the cable is 100% compliant with EIA/TIA standard if it is not connected to RJ-45 in the way it should be.  The Straight-through cable ("Patch cable") connection should be:

    Pin 1 and 2 are connected to same twisted pair wire
    Pin 3 and 6 are connected to same twisted pair wire
    Pin 4 and 5 are connected to same twisted pair wire
    Pin 7 and 8 are connected to same twisted pair wire


Here is the pin-out for Crossover cable ("Uplink cable"):
Point A         Point B
TR+     Pin 1     -----     Pin 3     RCV+
TR-     Pin 2     -----     Pin 6     RCV-
RCV+     Pin 3     -----     Pin 1     TR+
RCV-     Pin 6     -----     Pin 2     TR-