Logic of Crossover Cable

[jean-paul martell]

hi,
i want to know that logic in ethernet cable crossing 1,3,2,6.i Have to Handle 10 Sites.A crossover cable is for connecting computers directly.
Any recommendations and suggestions are appreciated.

[Zachary]

Devices that transmit on pin 1,2 and receive on pin 3,6 are--
1)-PC's NIC 2)-Router 3)-Wireless access points 4)-Printer directly connected to lan

Devices that transmits on pin 3,6 and receive on pin 1,2 are----
1)switch 2)Hub

Logic of crossover cable--
We can see that both PC and router transmit on Pin 1,2 and receive on pin 3,6.
so when we connect PC to router's ethernet port we will have to swap the wires....as PC will tranmit on Pin1,2 and router will receive the data on pin 3,6. hence we use crossover cable.

[Shen]

A normal ethernet cable allows only one way data transmissions while a crossover cable allows both way data transmission.
This is achieved by connecting the transmission pins (TX+ & TX-) of one end to the receiving pins(RX+ & RX-) of the other end. In a normal ethernet cable, this is done internally by the hub / switch or the router.

In a normal RJ45 / CAT5 ethernet cable, the pins are marked as 1. TX+, 2. TX-, 3. RX+, 6. RX- at both ends. To create a crossover ethernet cable we just connect the TX pins to the corresponding RX pins. In effect, we swap wires at the pins 1-3 and 2-6.

In a normal ethernet cable,
We have the following pin configuration at both ends:

1: TX+
2: TX-
3: RX+
6: RX-

While in a crossover cable, we have:

Crossover
1: TX+ <—-> 3: RX+
2: TX- <—-> 6: RX-
3: RX+ <—-> 1: TX+
6: RX- <—-> 2: TX-

We let the Pins 4,5,7,8 remain unaltered.

[Big Fish]

Logic means pinouts

E.g.

Straight cable
1-------------1
2-------------2
3-------------3
4-------------4

Cross cable pin out is
RD+1---------------3TD+
RD-2----------------6TD-
TD+3----------------1RD+
TD-6-----------------2RD-