Introduction of Networks

Introduction of computer networks

A network is a set of devices (often referred to as nodes) connected by some means of communication medias or links. A node can be a computer, printer, or any device capable of sending and / or receiving data generated by other nodes on the network. A computer network is a collection of computers and other devices connected by some means of communication channels that facilitate communication among users and allows user to share resources with other users. Some features of computer networks: >> Distributed Processing : Most networks use distributed processing, in which a task is divided among multiple computers. In this system instead  of single large machine being responsible for all aspects of a process, separate computers handle a subset. >> Network Criteria : A network must be able to meet a certain number of criteria. The most important of these among several of them are ; Performance Reliability Security >>Performance Performance of any network can be measured in many ways, including transit time and response time. The transit time is the amount of the time required for a message to travel from one device to another device. The response time is the time consumed between an inquiry and a response.The performance of a network depends on a number of factors, including the number of users, the type of transmission media, the capabilities of the connected hardware, and the efficiency of the software components. Performance is often evaluated  by two networking components: throughput and delay. Main purpose of any network is to bring the more throughput and less delay. That mean we need more throughput and less delay. However, these two criteria are often contradictory. If we try to send more data tot the network, we may increase the throughput but we also increase the delay because of the traffic congestion in the network. >> Reliability  The system which must send / deliver  the data to the correct destination as well as it is also necessary for any system to send the data more accurately. In addition to accuracy of delivery, network reliability is measured by the number of times of failure, the time it takes a line to recover from a failure, and the network's robustness in a catastrophe. >> Security Network security issues include protecting data from unauthorized access. It also handle the issue of protecting the data from damage and development, and implementing policies and procedures fro recovery from data losses.