RJ45 is an ethernet cable connector that functions as a connector on a LAN(Local Area Network)network topology and other network topologies.
RJ stands for Registered Jack which is standard equipment on a network that regulates the installation of connector heads and the order of wires to connect equipment in the network.
This connector can be found on UTP or Unshielded Twisted Pair cables as well as STP cables or Shield Twisted Pair.
Each connector on the RJ45 has eight pins with eight separate cables. Each cable has a different color and the order in which it is installed has its own rules. There is an international standard of color order in sorting such cables.
T-568A RJ45 Pinout
T-568B RJ45 Pinout
The TIA/EIA 568-A standard was ratified in 1995 and replaced by TIA/EIA 568-B standard in 2002 and has been updated ever since. Both standards specify the T-568A and T-568B pinouts on unshielded twisted pair cables and RJ-45 connectors for Ethernet connections.
Cable straight through
A straight-through ethernet cable is a type of cable on a LAN to connect a computer to a network hub/switch such as a router. This type of cable has another name“patch cable”. In this straight-through cable using one standard cable, can both ends use the standard T-568A cable or both ends use the standard T-568B cable.
A type of ethernet crossover cable is a type for connecting computer devices directly. Unlike straight-through cables, the RJ45 crossover cable uses two different cable standards: one end uses the T568A cable standard, and the other end uses the T568B cable standard.
RJ45 cable system diagram
By looking at the T-568A straight-thru cable and crossover cable with the end of the T-568B, we see that the TX pin (transmitter) is connected to the corresponding RX (receiver) pin, plus to plus and minus to minus.
You can also see that the blue and brown cable pairs on pins 4, 5, 7, and 8 are not used in either standard. So why bother using this cable ??? The answer is to wait for the next article…