Computer Concepts and Applications – Computer Networking
DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER TWO Computer Concepts and Applications – Computer Networking CRT04207 · Radiology Informatics START READING NOTES Study Computer Concepts and Applications – Computer Networking using the sections below. Use the topic navigation to continue through Radiology Informatics. Computer Concepts and Applications – Computer Networking 4 Importance of networking 4.1 Introduction Information and communication are two of the most important strategic issues for the success of every enterprise. While today nearly every organization uses a number of computers and communication tools (like telephone or fax), they are often still isolated. While managers today are able to use applications like wordprocessors or spreadsheets, not very many of them use computer-based tools to communicate with other departments or information retrieval programs. To overcome these obstacles in an effective usage of information technology, computer networks are necessary. They are a new kind of organization of computer systems produced by the need to merge computers and communications. Computer networks can manage to put down the barriers between information held on several systems. Only with the help of computer networks can a borderless communication and information environment be built. 4.2 Importance of Networking Computer networks allow the user to access remote programs and remote databases either of the same organization or from other enterprises or public sources. Computer networks provide communication possibilities faster than other facilities. Because of these optimal information and communication possibilities, computer networks may increase the organizational learning rate there are other reasons why any organization should have a computer network cost reduction by sharing hardware and software resources high reliability by having multiple sources of supply cost reduction by downsizing to microcomputer-based networks instead of using mainframes greater flexibility because of possibility to connect devices from various vendors A network is two or more computers connected together to share information and files between them. Businesses aren't the only ones that can benefit from creating a network. Home users can enjoy sharing music, movies and printers from any computer. File Sharing : Computers connected to a network can share files and documents with each other. Personal computers connected to a business network can choose which files and folders are available to share on the network. Printers : Computers can print pages to another computer with a printer on the network. Additionally, printers can be connected using a print server, which allows direct printing from all computers. 4.3 Computer Network 4.3.1 Types of Networks A)Local Area Networks Local area networks (LANs) are used to connect networking devices that are in a very close geographic area, such as a floor of a building, a building itself, or a campus environment. B)Wide Area Networks C)Wide area networks (WANs) are used to connect LANs together. Typically, WANs are used when the LANs that must be connected are separated by a large distance. D)Metropolitan Area Networks A metropolitan area network (MAN) is a hybrid between a LAN and a WAN. A computer network is an interconnection of various computer systems located at different places. In computer network two or more computers are linked together with a medium and data communication devices for the purpose of communicating data and sharing resources. The computer that provides resources to other computers on a network is known as server In the network the individual computers, which access shared network resources, are known as workstations or nodes. Computer Networks may be classified on the basis of geographical area in two broad categories. Local Area Network (LAN) Wide Area Network (WAN) I. Local Area Network: Networks used to interconnect computers in a single room, rooms within a building or buildings on one site are called Local Area Network (LAN). LAN links computers, i.e., software and hardware, in the same area for the purpose of sharing information. Usually LAN links computers within a limited geographical area because they must be connected by a cable, which is quite expensive. Major Characteristics of LAN are as follows: Every computer has the potential to communicate with any other computers of the network High degree of interconnection between computers Easy physical connection of computers in a network Inexpensive medium of data transmission High data transmission rate Advantages of LAN are as follows: The reliability of network is high because the failure of one computer in the network does not effect the functioning for other computers. Addition of new computer to network is easy. High rate of data transmission is possible. Peripheral devices like magnetic disk and printer can be shared by other computers. Disadvantages of LAN is If the communication line fails, the entire network system breaks down. Use of LAN : Followings are the major areas where LAN is normally used File transfers and Access Word and text processing Electronic message handling Remote database access Personal computing Digital voice transmission and storage 4.4 Network Components 1)Hub A hub works in the physical layer of the OSI model. It is basically a non-intelligent device, and has no decision making capability. What a Hub basically does is take the input data from one of the ports and broadcast the information to all the other ports connected to the network. Port network To demonstrate its working, consider a 4 port network as shown in Fig 1. There are 4 computers connected to the 4 ports. Suppose, if Computer A wants to send some data to Computer B using a Hub, then, Computer A broadcasts the data on the network, and Computer B, being connected to the network, has access to the data. But, in this case all the other ports connected to the network has access to the data that is being transmitted by Computer A. This happens because, the Hub works in the Physical Layer and hence it does not know about the MAC addresses of the ports connected to the network. So, there is a lack of security in the Hub. USB Hub The picture shows a USB Hub, wherein the data is fed into the input port and is broadcasted