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Data network is the electronic ability to exchange information/ facts (data) among computers or devices connected to each other. Data networking can also be defined as the electronic process which enables data like letters and any other documents. Thus the main reason for the creation of data networks is to share these specific resources-data. Data is the fundamental thing in computing and thus there is a need to be able to share, send receive and transmit it with ease.
During data transmission, the network used uses 'data packets' to accomplish this goal. This is done in such a binary (zeros and ones) manner. These data packets also need to have addresses i.e. where they are being sent to and also to show where the data originated from (sender). There exist various different types of these data networks and their variety depends on the equipment used in creating them, the principles they use to transmit data and also the places they are well applicable at.
How Data is put on cable by computers on the cable
There are several types of cables that are used to transmit data. These cables have evolved with technology and the most recent cables are more efficient, reliable and fast compared to the first or the ancient cables. . The cables used in data transmission include; coaxial cables, the double twisted pair cable and the most recent one- the optical fiber cable. These different channels through which data goes through, uses some of the following principles; electromagnetic principle, electrical principle, light or optical principle and even acoustic waves principle
For data to be transmitted and be understood by a computer there must be a transmission line or a transmission channel. The data has to also be; first in a machine understandable form (0's and 1's). This data hence has to go through the process of being converted to this binary form. This process is often referred to as encoding/ modulation process. The device that computers use to convert/ encode this data before transmission is called a modem. Its purpose is to transform outgoing digital data and also is used on the other 'end' to decode/ convert back at the recipient.
Ensuring data reaches the destination undamaged
Most of the data that is transmitted is important and at times even confidential. The presence of some unruly persons that may mischievously tamper with it brings about the need to protect/ secure it hence avoiding corruption and unauthorized access.
Encryption of data helps achieve this goal by converting it into mathematical schemes and algorithms thus making it illegible before it reach the recipient. The data is only decrypted at the recipient since its where the associated key can be found.
Firewall is another way of safeguarding data. Firewall monitors network traffic and alert you of anyone who tries to access your computer. This hence aids in keeping computer crackers out of the system. It can also block any unauthorized person from accessing your system. Firewall does not only prevent persons, it also bounds unauthorized applications from communicating with your computer.
Access methods refer to rules set to control how network points share and split the transmission channels.
Contention access method: In this transmission method, computers compete for chances to transmit their data. They use a 'first-come, first-served' ideology. Whichever computer that gets a chance first gets to transmit first. Initially, this was not a favorite of transmission modes since most of the times it crashes as a result of collision every time there is an attempt to transmit data. This method can however be easily usable with the aid of 'carrier sensing' which enables computers to avoid transmission if they sense that the network is busy. Applying 'carrier detectors' also enables ease the confliction in the network as this helps computers end transmission if they sense another transmission coming up.
Packet switching: In this networking method, data is grouped into suitably-sized blocks (packets). These are the ones that are shared over a network. The biggest draw back of this method is the delay caused by buffering and queuing of these packets. Packet switching can be connectionless which includes address and route information or it can be connection-oriented which only has an identifier.
Token passing: This as a very orderly mode of transmission that involves a computer allowing others an opportunity 'token' to transmit as it finds a message to do the same. In this mode, data goes around the network and when it gets to the recipient, the sending computer receives a signal that it has. This mode ensures all computers share the channel equally. This method allows very rare cases of signal collision.
Demand priority: This transmission mode ensures fairness in accessing the network by all computers. Its uses round-robin method to allow each computer equal opportunity to transmit data. The method is efficient for transmitting multimedia data like photos and videos too especially with a bandwidth allocator in place to limit and regulate the amount of bandwidth that can be used every time. This is a highly recommended method especially in places with massive data transmission as the bandwidth is adjustable and can transmit a wide variety of data range.
Polling: In this method of transmission, every computer gets access to the channel and in a certain order. A message called a poll is used to give permission for transmission. The two types of polling are; hub polling (centralized) where a computer sends signal to the hub when it's done so that the hub can signal the next computer and/or distributed polling (decentralized) whereby each computer knows who follows next and thus signal that computer directly. Polling can either be gated, exhaustive or partially gated. Polling is a practically good method as it rarely encounters the collision problem.
Need for access methods
Different channel access methods are applicable in different environments depending on the traffic and other considerations. For instance in a network that will involve transmission of multimedia data, demand priority channel access method is very suitable. When choosing an access method avoidance of collision is a key factor, this is because a data network will always fail when collision happens. For instance, in contention method, the carrier detectors and sensors are employed to avoid the frequent crashes caused by colliding data signals. I token passing protocol, a 'token' is used to avoid the same and so is a 'poll' in the polling protocol.
The Media Access Control sub-layer is the link between the Logical Link Control (LLC) sub-layer and the network's physical layer. It uses a full-duplex logical communication channel and may give single-cast, multicast or broadcast service. MAC enables computers to connect to one physical medium and to share it within the network.