What is RJ45 Interface?

What is RJ45 Interface?

Cables transmit information along the length. Only the right connection to an RJ45 interface or RJ45 connector will realize the transmission. And the cable run needs a connector termination, requiring a jack, normally an RJ45 jack, to plug into. RJ45 connectors are commonly seen with Ethernet network cables. Ethernet cables with RJ45 connectors are also called RJ45 cables. These RJ45 cables feature a small plastic plug on each end, and the plugs are inserted into RJ45 jacks of Ethernet devices.
RJ45 is a type of cable connector which is mainly used in computer networks. RJ45 is mainly used for ethernet networking which is used to connect different type of devices like a switch, hub, PC, router, firewall to each other.RJ45 is the most known and popular connector type in the IT world.What is RJ45? Are you confused about different RJ45 interface types? Keep reading to explore more.

What Is RJ45 Interface?

RJ45 interface is considered the most common twisted-pair connector for Ethernet cables and networks.
"RJ" means "registered jack" — a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long-distance carrier.
"45" is the number of the interface standard.
Physically speaking, the connectors that registered jacks use are mainly the modular connector and 50-pin miniature ribbon connector types. RJ45 connector is an 8-position, 8-contact (8P8C) modular plug, and jack, applied for Ethernet-based local area networks (LAN). RJ45 cable plug is usually made of a plastic piece with eight pins on the port. Four of the pins are used for sending and receiving data, and the other four are used for other technologies or power networking devices.

RJ Stands For Registered Jack

Well, where the RJ comes from. RJ means Registered Jack and standardized network interface to connect voice and data equipment. There are other RJ standards like RJ11, RJ14, RJ25, etc. For example, in order to connect the phone to the copper line RJ11, standard and connector are used.

RJ45 Parts

Even RJ45 Connector is very simple connector it consists of different parts.
  • Copper pins which will stick with the copper lines.
  • Clip to stick RJ45 to the RJ45 port and release
  • Crimp to put the cable to the RJ45 connector.

RJ45 Cabling

RJ 45 connector consists of 8 pins where 8 copper lines are connected. RJ45 generally used for CAT5 and CAT6 cables. There are two standards used for RJ45 named T-568A and T-568B. They are the same cables but with a different lineup.

How to Identify RJ45 Interface Color Code?

T568A vs T568B are the two common wiring schemes, which are used to terminate the twisted-pair cable onto the connector interface. The two standards define how the RJ45 pinouts arrange the individual eight wires when linking the RJ45 connector to a cable. These wiring layouts have their own color convention to follow for electrical compatibility. The T-568B wiring scheme is considered to be the more commonly used one.
The differences between T568A vs T568B in color conventions are shown in the figure below.
With regard to the two standards, there are two different connectivity forms. If both ends of the patch cords are wired on the basis of one standard, it is a straight-through connection. If not, it is a crossover connection. Some networking applications require a crossover Ethernet cable, which has a T-568A connector on one end and a T-568B connector on the other. This type of cable is typically used for direct computer-to-computer connections when there is no router, hub, or switch available.

RJ45 Cable Types

Cables that terminated with RJ45 connectors on both ends called RJ45 Ethernet cables. Cat5, Cat6, and Cat7 cables are the most common RJ45 cables used in today's network connection.
Category 5 (Cat5): The category 5 or cat5 RJ45 cables feature two twisted-pair cables that enable a maximum of 100 meters of transmission. These cables are ideally used for transmission of 100MHz frequency at the speed of 100Mbits per second. The advanced or upgraded version of cat5 cables is available called cat5e which uses 4 twisted pair cables. This version of cat5 cables is capable of transmitting data at gigabit frequencies over a short transmission distance.
Category 6 (Cat6): This category of RJ45 cables features improved shielding and stringent transmission standards. These cables offer 1000Mbit per second transmission at a transmission frequency of 250MHz. The upgraded version Cat6a offer 500MHz of transmission frequency.
Category 7 (Cat7): The Cat7 cables are designed for 600MHz transmission frequency in 10 Gigabit Ethernet networks. These cables feature hardwired construction. An upgraded version of these cables, Cat7a offers 100MHz of transmission for 40/100-gigabit transmission speeds.

RJ45 Cable Applications

RJ45 connectors are the key part of Ethernet connectivity to transmit voice and data media. They were developed as much smaller and cheaper replacements to the older telephone installation methods of hardwired cords. The easy plug-n-play style reduces the difficulty of installation. Compared with RJ11, RJ45 is suitable for more applications, such as Ethernet networking, telecommunications, factory automation, and so on. It is frequently used for networking devices including Ethernet cables, modems, computers, laptops, printers, etc.


Now that the RJ45 interface is discussed thoroughly, the RJ45 cables and switches with RJ45 jacks can be used effectively in the Ethernet networks. However, the quality of RJ45 jacks and cables, and switches must be assured to get efficient and reliable performance.
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