Ethernet Cable and RJ45 connectors

  • Network
Ethethernet cable-RJ45 connector

RJ45 connectors

RJ 45 is 8P8C (8 positions 8 Pin) connector which is used in Ethernet networking for terminating the CAT5e or CAT6 and other Ethernet cables. It resembles RJ11 telephone jack but RJ45 its slightly bigger in size then RJ11. The term RJ means “ Registered Jack” and 45 is an interface standard. Each RJ45 connector is having 8 pins in which the 8 pairs of Ethernet cables are crimped. The eight different color wires in Ethernet cable are arranged and crimped in RJ45 according to the predefined standards. The RJ45 connectors are inserted in the socket which is called “RJ45 jack”.

When we say that computers are in the wired network we will see an R45 wall jack behind every Desktop or laptop and same RJ45 port you can see on your desktop or laptop near USB port or back of PC. Wall jacket and RJ45 port on the computer are joined together by a Cable with RJ45 connecter crimped at both ends. This cable is also known as patch cable.

There are two types of RJ45 ethernet cable crimping standards they are T-568A and T-568B. The cables in two standards are crimped as per the following color codes.

RJ45 Connector Crimping standards

RJ45 Pin Layout

 According to the pin layout, RJ 45 is of two standards and the T-568B Crimping is the most used connection, If both ends of the Ethernet cable are wired as per one above mentioned standard, it is called straight cable connection. Both the standards can be used for straight cable. If the cable is crimped with T-568A connector on one end and a T-568B connector on the other this cable is called crossover connection cable. This type of connection is normally used for direct computer-to-computer.

whether you choose the A or B wiring standard if both ends of the cable are wired using the same standard then this is known as a straight cable which is also known as a patch cable, a straight cable allows signals to pass through from one end to another end this is the most common type of cable that’s used in local area networks. A straight cable is used to connect computers to hubs switches routers or modems or in other words it’s used to connect dissimilar devices together and a Cross cable is generally used to connect similar devices.

Ethernet cable

Ethernet cable commonly known as LAN cable is used to connect the devices in networking. While connecting to the device they are terminated with are RJ45 Connecters. While selecting the Ethernet cable for networking we generally come across the term CAT cable such as CAT 5, CAT6, CAT7, etc. Here the term CAT is used for ‘Category’ and the number after is word CAT is the version of the cable.

There are two types of Ethernet cables Unshielded twisted pair (UTP) and Shielded twisted pair (STP), UTP is four paired wire twisted to reduce noise and crosstalk. In the same way, STP is the same wire of four pairs as UTP but shielded with foil to reduce noise and electromagnetic inductions.UTP is the most commonly used cable for home and offices and STP is normally used for industrial purpose andRJ45 connectors are crimped to ends twisted pair cables. There are many categories and versions of twisted-pair cables such as CAT3, CAT5, CAT6 and CAT7 depending upon the speed they can transmit without any noise or electromagnetic induction. Let’s discuss them one by one.

CAT3 and CAT5 cable

CAT3 cable which was first used in networking is now discontinued due to it limitations

CAT5 is designed to transmit at a bandwidth of 100Mhz. CAT5 uses 2 twisted pairs whose maximum length range 100 meters.


The Cat5e is an enhanced version of the cat5 cable that was launched in 2001 with four twisted pairs. CAT5e cables can transmit up to 1000 Mbps means 1 gigabyte per second. Cat5 cables are normally used in home and small area networking.


CAT6 cables have more speed than CAT5 cables and four pairs of twisted wires are tightly wound in a cable with a thin separator. This separator isolates four pairs of wounded twisted pairs of wires from each other’s so the crosstalk between pairs is reduced and data transfer, with faster speed, can be done, CAT 6 cable support speed up to 10 Gbps with a frequency of 0-250Mhz(minimum) up to 500Mhz., The theoretical length of CAT6 cable length for networking is 55 Meters.


In CAT6a cable “a” means “augmented”. These cables also have 4 twisted pair cables with a separator which is denser and less flexible than CAT6 cable. CAT6a cables have the speed of 10Gbps the same as CAT6 cable with a frequency of 500 Mhz. They have a higher transmission rate over a long length of up to 100 meters.


CAT7 is a cable designed to provide an additional increase in bandwidth with more reduction in crosstalk and noise. It is designed to transmit frequencies of up to 600 MHz with high speeds, Cat 7 cables transmit to 100Gbps at a range of 15 meters, so they are used to for connecting modems or routers directly to your devices. CAT7 cables use Gigagate45 (GG45)connectors instead of RJ45 but also have the backward compatibility with RJ45 connectors. The theoretical length of the CAT7 cable is 100 meters.


Same as CAT6 has a CAT6a version, CAT7 also has a CAT7a version which was developed to support 40 Gbps Ethernet connection with frequency up to 1000 Mhz. It can support 40 Gbps up to 50 meters and 100 Gbps connection up to 15 meters in ideal circumstances. 


Comparison table

CABLE TYPEDATA transmit SpeedMax bandwidthSheilding
CAT310 Mbps16MhzUTP
CAT510/100 Mbps100MhzUTP
CAT5e1000 Mbps100 MHzUTP
CAT61000 Mbps250MhzUTP or STP
CAT6a10,000 Mbps500MhzSTP
CAT710,000 Mbps600MhzSSTP
CAT7a10,000 Mbps1000 MHzSSTP

Crimp an Rj45 Ethernet cable

Let’s see how to crimp Ethernet cable and RJ45 connector.

1. Cut 1 inch plastic sheath of cable with blade of crimping tool and peel inner twisted pairs out.

2. Unwind the pairs of the cables

3. Trim any nylon threads from that area

4. Straighten the cables and arrange them according to the color code of the required pin out .

5. Cut all the cables in same length and arrange them in straight manner.

6. Insert the wire in RJ45 connectors and push them forward so that the wires reach the front of RJ45 and below the connector pins evenly.

7. Crimp the connector inserting it in to crimping tool.

8. After crimping test the cable

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