Classification of Computer Networks and Topologies Explained

INFORMATION NETWORKS AND INTERNET JALAL QAIS JAMEEL (ASSISTANT LECTURER, COLLEGE OF MEDICINE / MUSTANSIRIYAH UNIVERSITY)

COMPUTER NETWORK A collection of autonomous computers interconnected by a single technology. Two computers are said to be interconnected if they are, infrared, and communication satellites can also able to exchange information. The connection can be via a copper wire; fiber optics, microwaves be used

USE OF COMPUTER NETWORKS A-FOR COMPANIES OR BUSINESS APPLICATIONS Resource sharing Sharing information Powerful communication Electronic commerce

USE OF COMPUTER NETWORKS B- HOME APPLICATION Access to remote information Person-to-person communication Electronic commerce

CLASSIFICATION OF NETWORKS CLASSIFICATION OF NETWORKS BY SCALE LAN (Local Area Network): physical distance between the hosts is within a few kilometers. LANs are typically used to connect a set of hosts within the same building (e.g., an office environment) or a set of closely-located buildings (e.g., a university campus). Three standard types of LAN: Ring, Bus, and Star topology. MAN (Metropolitan Area Network): MANs cover distances of up to a few hundred kilometers and are used for interconnecting hosts spread across a city. WAN (Wide Area Network): used to connect hosts spread across a country, a continent, or the globe. Usually WAN have a random topology.

CLASSIFICATION OF NETWORKS BY TOPOLOGIES BUS TOPOLOGY: Uses a backbone to which all of the computers on the network are connected. At any instant one machine is the master (allowed to transmit), all other machines are required to refrain from sending. Coaxial cablings (10 BaseT, 10Base5) were popular options.

CLASSIFICATION OF NETWORKS BY TOPOLOGIES BUS TOPOLOGY Disadvantages of Bus Network disruption when computers are added or removed A break in the cable bus will prevent all systems from accessing the network. Difficult to troubleshoot. Need of arbitration process Advantages of Bus Cheap and easy to implement equipment. Supported by most software and hardware systems Require less cable Does not use any specialized network

CLASSIFICATION OF NETWORKS BY TOPOLOGIES RING TOPOLOGY: Logical ring meaning that data travels in circular fashion from one computer to another on the network.

CLASSIFICATION OF NETWORKS BY TOPOLOGIES RING TOPOLOGY Disadvantages of Ring Advantages of Ring Cable faults are easily located, making troubleshooting easier Ring networks are moderately easy to install Better with high traffic rates than Ethernet Expansion to the network can cause network disruption A single break in the cable can disrupt the entire network. Great deal of maintenance and not suited for large networks

CLASSIFICATION OF NETWORKS BY TOPOLOGIES STAR TOPOLOGY : All computers/devices connect to a central device called hub or switch. Each device requires a single cable point-to-point connection between the device and hub. Most widely implemented

CLASSIFICATION OF NETWORKS BY TOPOLOGIES STAR TOPOLOGY Disadvantages of Star Advantages of Star Requires more cable Easily expanded without disruption to the network Cable failure affects only a single User A central connecting device allows for a single point of failure More difficult to implement Easy to troubleshoot and isolate problems Low traffic requires a low specification twisted pair cable

CLASSIFICATION OF NETWORKS BY TOPOLOGIES MESH TOPOLOGY : Each computer connects to every other. High level of redundancy. Rarely used. Wiring is very complicated and Cabling cost is high Troubleshooting a failed cable is tricky A variation hybrid mesh create point to point connection between specific network devices, often seen in WAN implementation

CLASSIFICATION OF NETWORKS BY TOPOLOGIES MESH TOPOLOGY Disadvantages of Star Advantages of Star Requires more cable than the other LAN topologies Provides redundant paths between devices The network can be expanded without disruption to current uses Complicated implementation

CLASSIFICATION OF NETWORKS BY TOPOLOGIES WIRELESS NETWORK : Do not require physical cabling Particularly useful for remote access for laptop users Eliminate cable faults and cable breaks. Signal interference and security issue.

CLASSIFICATION OF NETWORKS BY TOPOLOGIES MESH TOPOLOGY Disadvantages of Star Advantages of Star Allows for wireless remote access Potential security issues associated with wireless transmissions Network can be expanded without disruption to current users Limited speed in comparison to other network topologies

THE INTERNET (CONCEPTS/TERMS) HTTP Hypertext Transfer Protocol - is the method used for transferring data over the Internet. It is a set of rules which allows browsers to communicate with servers and exchange files, including text, graphic, music and video files. These letters are commonly seen at the beginning of a web address. URL Uniform Resource Locator is an address for a resource on the Internet. It is basically the Web address for a site on the Internet and is seen in the Locator box when you visit any Web site. This is often pronounced you-erl or earl . Hyperlink this is a link in a Web document which connects to information in another document. It is usually highlighted in the text, and sometimes is underlined as well, but it can also be an image or graphic. When you click on a Hyperlink on a Web page it takes you to another Web page or another section of the current Web site. ISP Internet Service Provider a company that provides access to the Internet. These companies usually charge a fee and provide the user with a dial-up number, cable access or a satellite connection which allows use of their computer system and services. FTP File Transfer Protocol is the language used to transfer files between computers on the Internet. HTML Hypertext Markup Language is a standardized coding language used to create Web pages. It is not a programming language, but instead controls the design and links on the pages of a website.

STRUCTURE OF A WEB ADDRESS A Web address (URL) is a string of characters and symbols which create a unique Web address for specific sites. There are no spaces in a Web address. The URL is composed of: 1. The first part of a web address shows the type of resource (protocol) used to locate the address (usually HTTP://). 2. The next part of the address indicates the actual address of the Web site. This is the 'domain' name which the site owner must purchase from a registered Internet 'agent'. Example:www.Hotmail.com. WWW indicates that it is a World Wide Web address, Hotmail is the Domain name and .com is the extension. 3. Domain names can have different extensions, depending on the content and domain agent. Typical extensions are: .com - commercial .net - network .gov government .info information service .org - organization .edu education .it, .ca, .ng, .na, etc. country codes