A network is a system of interconnecting computers, which are located away but connected with each other through a communication media like wire cable and other networking devices. The main goal of having computers connected to a network is to achieve data communication between two devices. Networking provides the platform to share resources available in a system with those connected via network. Some of the valuable resources available in a computer are: CPU, memory, printers and files.
Data Communication is a process of exchanging data, which is a valuable resource in any network, between two devices connected via some form of transmission media such as wire cable or optical fiber. The data available in a computer may be stored in different forms which include text, numbers, images, audio and video.
In networks, data communication takes place with the help of communication devices, which are made up of hardware (physical equipment) and software (programs). The effectiveness of data communication depends on four fundamental characteristics: Delivery, Accuracy, Timeliness and Jitter.
Delivery: This characteristic refers to the probability of data delivered to the correct destination. The data sent via a network must be received by the intended device or user and not by anyone else on the network.
Accuracy: This refers to the possibility of sending the data accurately between two systems. Data that have been altered during transmission are corrupted and are not usable at the receiving end.
Timeliness: This characteristic determines the timely delivery of data in its transmission. Data delivered late are useless. In the case of video and audio, timely delivery means delivering data as they are produced, in the same order that they are produced, and without any significant delay. This kind of delivery is called as real-time transmission.
Jitter: Jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of audio or video data. For e.g., let us assume that video packets arrive at a time delay of 30 ms. If some packets take 40 ms for their arrival, it results in an uneven quality in the video.
A network, which acts as a carrier for data communication, comprises of five major components namely message, sender, receiver, transmission media and protocol. They are explained as follows:
Message: The message is the information to be communicated. It may be in any one of the five popular formats: text, numbers, pictures, audio and video.
Sender: The sender is the device that sends the message. It can be a computer, a telephone handset, video camera and so on.
Receiver: The receiver is the device that receives the message. It can be a computer, a telephone handset, video camera and so on.
Transmission Media: This is the physical path by which a message travels from the sender to the receiver. Some examples of transmission media include twisted-pair cable, coaxial cable, fiber-optic cable and radio waves.
Protocol: A protocol is a set of rules that govern data communication. It represents an agreement between the communication devices. It is in both abstract and concrete forms. Logically, a protocol is defined as a set of rules, but physically it is implemented either in hardware or software.
Without a protocol, two devices may be connected but not communicating the data across. For two devices to communicate successfully, they must speak the same language. The protocol specifies the rules for what is to be communicated, how it is to be communicated, and when it is to be communicated between two devices.
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