crossover cable
Crossover cables are connection cables with a crossover function. In contrast to patch cables, which are also called straight-through cables, the transmitting( TX) and receiving (RX) lines of crossover cables are usually swapped. Whereas the other lines occupy the same contact.
With crossover cables, two end devices can be directly connected to each other because the transmit lines of one connector are connected to the receive lines of the other connector. For example, in an Ethernet crossover cable with an RJ45 connector, the transmit and receive lines could be reversed. This means that contact 1 of connector 1 is connected to contact 3 in connector 2, and contact 2 of connector 1 is connected to contact 6 of connector 2, and so on.
With such a crossover cable with swapped transmit and receive lines, two end devices can be directly connected to each other via the network cards without the need to interpose a hub or a switch.
In addition to crossover cables, there are also crossover adapters that functionally correspond to crossover cables and in which only the transmit and receive lines, Transmit(Tx) and Receive( Rx), are swapped with each other.