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Insight - How Ethernet Cable works

Written By: 

Arpit Jain
If you ever connected a PC with a broadband connection you surely used an Ethernet cable to do it. Ethernet cables also called LAN cables or Cat 5 cables are often used in home networks. They are categorized into two types – Straight through and Crossover cables. Straight though cables are used to connect different types of devices (like PC to Hub) whereas Crossover cable is used to connect same type of devices such as PC to PC or Switch to Switch. Both the cables are almost identical except the wiring scheme of their end connectors. Click to know more about ethernet.

A Regular Ethernet Cable

Fig. 1: A Regular Ethernet Cable

Shown in the image is an Ethernet cable used to connect two network devices having a connector at both ends. Depending on the type of the cable, straight through or crossover, both end connectors either have same or different types of wiring schemes, respectively. This article covers a straight through cable.


Closer Look At A Typical Ethernet Cable Connector

Fig. 2: Closer Look At A Typical Ethernet Cable Connector

The connector consists of a mechanical lock which aids to fix the cable in the port. Once a cable is thoroughly plugged into the device port a click sound is produced.

A RJ45 Cable Connector

Fig. 3: A RJ45 Cable Connector

The connectors used here are RJ45 also known as 8P8C (8 position 8 conductor) connectors. As the name specifies it contains 8 pins for connections. The 8P8C connector is generally used to terminate a twisted pair or multi-conductor flat cable.

Internal Wires

Image Showing Wires Present Inside Ethernet Cable

Fig. 4: Image Showing Wires Present Inside Ethernet Cable

Inside the Ethernet cable, there are 8 color coded wires. These wires are twisted into 4 pairs of wires with each pair having a common color theme. One wire in the pair is a solid or primarily solid colored wire and the other is a primarily white wire with a colored strip. Examples of the naming schemes used are: Orange for the solid colored wire and White Orange for the striped wire.  

Images Showing Cable Wires With (Left) and Without (Right) Polyethylene Layer

Fig. 5: Images Showing Cable Wires With (Left) and Without (Right) Polyethylene Layer

Wires are plain copper wires with a well defined thickness and are insulated by a polyethylene layer.
Below shown are the color codes for each pin of the straight through cable:

According to the pin configuration shown in the diagram, first two pins (TX+, TX-) are used as transmitter  while the pin numbers three and six (RX+, RX-) work as receiver for the PC.

Fig. 6: Image Showing Various Colors of Wires Present Inside Ethernet Cable

The twists between each pair of wires are extremely important. They are there to counteract noise and interference.

 Wires Arrangement

Typical Wire Arrangement Inside Ethernet Cable

Fig. 7: Typical Wire Arrangement Inside Ethernet Cable

Making a LAN cable is quite simple, arrange the wires of the twisted pair cable in the predefined arrangement (as per the type of the cable) and put them in the connector as shown in the next image.

Crimping Tool

A Crimping Tool is used to crimp the RJ45 connector.
Once the wires are set, the connector is put between the slot and crimped by pressing the handles of the tool.

Pins of Connector

A Closer View of Pins Inside Connector

Fig. 8: A Closer View of Pins Inside Connector

The eight pins are arranged in the connector in a way that they connect the wires with the device ports. 
Shape of connector pins

Fig. 9: Image Showing Arrangement of Pins Inside Ethernet Connector

Shape of the connector pins is shown in the image. At one side they hold the cable wire in its dent and other side connects with the device port when it is plugged in.