Understanding Computer Networks: Basics, Benefits, and Hardware, Dispense di Informatica

Scarica Understanding Computer Networks: Basics, Benefits, and Hardware e più Dispense in PDF di Informatica solo su Docsity! PC NETWORK PART 1 ABSTRACT This lesson shows you how computer networking works with few technical details. It explores the common parts of every computer networking and permits after learning the students to will be able to: • Define what a Computer Network is • List the benefits of networking • List different wired and wireless media for communication • Identify different network devices • Identify the type of network on the basis of area covered • Describe various terms associated with computer networks. • List various security threats to computer networks • Identify computers and users over a network • Setting up a computer network OVERVIEW A computer network is a collection of interconnected computers and other devices, which are able to communicate with each other and share hardware and software resources. But, before every other description, we must understand how a computer Network works, with few questions: have you ever worked on Internet? Or have you ever used an ATM? If you have doing one of these actions or if you have transferred a song from your computer to a cell phone or vice-versa, then you have experienced and utilized the services of a computer network. In this discussion, as just said above in learning objectives, I want to talk about various types of computer networks, their benefits, and what is required to create computer networks. What is advantages of networked computers? A few of these advantages are: • Resource Sharing • Cost saving • Collaborative user interaction • Time saving • Increased storage Let us discuss these advantages in some details. Resourse sharing and cost saving In a networked computer there’s one printer for all computers . It means that the printer is being shared by more than one users. Similarly other resources like Hard Disk, DVD Drive, and Scanner, software resources, etc. can also be shared on a computer network, with great cost-saving. Collaborative User Interaction and time saving: Let us take one more example of a school. Here we assume that all the computers in the school are connected to one main computer (called server). After a test or an exams, the teacher can obtain promtly results and he has to exchange marks with each other for result preparation. Similar is the case with other computerized organizations also. If we are working on a computer which is a part of a computer network, we can immediately communicate with any other user of the network through e-mail or chatting. sending and receiving messages and live videos, so it leads to increased productivity, cost-saving as well as time-saving. Increased Storage: On a network, same data may be replicated on multiple computers to ensure the availability of data in the case of some computer getting faulty. Like when you store your copies on some other data memories (usb pen, floppy, CD-ROM, etc.). On large networks also the data is replicated on multiple computers as if a huge storage area is available to store multiple copies of the data. Today, small as well as big organizations, and governments keep their data on servers. They share this data with authorized users and ensures security, Customer communication, assistance, information, etc. networks. These networks need to communicate with each other over the globe. A gateway is capable of understanding address architectures used in different networks and seamlessly translate between these address architectures. Network Topologies The way in which the computers/devices are physically interconnected to form a network is called a Topology. A Topology is an arrangement of physical connections among nodes in a network. Any device (Computer, Scanner, Printer, etc.) which is directly connected to a computer network is called a node. It can be a computer or any other device like printer, scanner etc. There exist different network topologies. Let us discuss only a few of them. Bus topology In bus topology all the nodes are connected to a main cable called backbone. The signal travels through the entire length of the backbone and is received by the node for which it is intended. A small device called terminator is attached at each end of the backbone. When the signal reaches the end of backbone, it is absorbed by the terminator and the backbone gets free to carry another signal. Star topology In star topology each node is directly connected to a hub/switch. If any node has to send some information to any other node, it sends the signal to the hub/switch. This signal is then broadcast (in case of a hub) to all the nodes but is accepted by the intended node(s). In the case of a switch the signal is sent only to the intended node(s). Tree topology Tree topology is a combination of bus and star topologies. It is used to combine multiple star topology networks. All the stars are connected together like a bus. This bus-star hybrid approach supports future expandability of the network Network Protocol The network devices will be able to communicate with each other only after they know the rules of communication. A set of rules in a network is known as a protocol. Protocols generally includes rules of how and when a device can send or receive the data, how is the sent data packaged, and how it reaches its destination. There are a lot of other communication protocols like HTTP, TCP/IP, PPP, SMTP, POP, UDP etc. Here we discuss two of them: HTTP and TCP/IP. 1- HTTP (Hyper Text Transfer Protocol) It is used to transfer all files and other data (collectively called resources) from one computer to another on the world wide web. When an HTTP client (a browser) sends a request to an HTTP server (web server) , the server sends responses back to the client. It is the basic protocol of the Internet. 2- TCP/IP (Transfer Communication Protocol/Internet Protocol) Allows Communication between two computers on internet. TCP/IP is a two-layer protocol. When data is to be sent from one computer to another over internet, it is first broken into smaller packets which are actually sent. When these packets are received by the receiver computer, they are assembled into the original message. This job of dividing the original message into packets and re-assembling the received packets into the original message is done following TCP protocol. Types of Networks A computer network may can be in a room, in a building, in a city, in a country, across continents or around the world. On the basis of area covered computer networks are classified as: • PAN - Personal Area Network is a network of Communicating devices (Computer, Phone, MP3/MP4 Player, Camera etc.) in the proximity of an individual. It can cover an area of a few meters radius. • LAN - Local Area Network A LAN is a network of computers in a room, building, or campus, like an office, a school, or a home. Occasionally a LAN can span a group of nearby buildings. If a LAN is setup using wireless media, it is called WLAN (wireless LAN). • MAN - Metropolitan Area Network is a computer network within a city. A good example of a MAN is the interconnected offices of a state government. • WAN -Wide Area Network A WAN crosses beyond the limits of a city, country, or continent. A network of ATMs, BANKs, National Government Offices, International Organizations' Offices are examples of WANs. The best known example of a WAN is the internet. Identification of computers and users over a network Network Security Setting up a computer network