The purpose of physical layer is to move data bits, ones and zeros from one end of a link to another end. The physical layer of any network stack model is the most complex architecture. Because very complicated mathematics, physics and electrical engineering principle combined together to transmit huge volume of data across tiny wire with incredible speed. In this article we will try to understand physical layer of any network model. Because this will help us to properly troubleshoot any networking issue and built up a new network.
Physical Layer | Networking Model
The Physical Layer consists of networking devices and medians that transmit data bits across computer networks. A bit is a small representation of data which is nothing but 1s and 0s that a computer can understand.
A standard copper network cable when connected devices both ends will carry a constant electrical charge. We actually send 1s and 0s across the network cable through a process called Modulation. The Modulation is a way of varying the voltage of charge moving across the cable. The term modulation when use for computer network refers to more specifically as Line Coding.
The line coding allows devices on either end of a link to understand the electrical charge in certain state is 1 and another state is zero. Through this simple technique of line coding modern network is capable of moving 10 billion of bits across a network cable every second.
Networking Cable | Duplexing and Simplexing
The most common type of network cable that connect computer devices is twisted pair cable. The cable name is twisted pair, because it pairs copper wire that twisted together. This pair act as a single condone for information. Also the twisted nature of the pair helps protect the information from the electromagnetic interference and crosstalk from neighboring pairs. Standard cat 6 cable has 8 wires consisting of four twisted pair inside. Utilizing number of pair depending on the transmission technology in use. But it is important to know that this cable is capable for duplex communication.
Duplex communication is a concept that information can flow in both directions across the cable. There is also another concept which is Simplex communication. This type of communication is unidirectional communication. Means transmission of data only go in one direction.
The way networking cable ensures that duplex communications are possible is by reserving one or two pairs for communication in one direction. Hence the other one or two pairs for communicating in the other direction. Also devices on the either side of the networking link can both communicate with each other at the exact same time refers to as Full- Duplex Communication.
If there something wrong with network connection then network devices operate in half-duplex. Half-Duplex means communication is possible in each direction but only one device can be communicating at a time.
Networking Ports | Physical Layer of Networking Model
Networking Ports are generally directly attached to the network devices. For example switches may have many network ports. Because their purpose is to connect many computer devices. Networking ports are the end point of network links. Most common cat 6 cable terminated with a plug namely RJ45 connector and RJ45 Ethernet port.
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