CHAPTER 7 NETWORK

1. TECHNOLOGY AND INFORMATION SYSTEMS DDC 1583 http://www.scribd.com/doc/63447967/Introduction-to-Information-Systems-3rd CHAPTER 7NETWORK The Telecommunication Systems Types of Networks Network Fundamentals The Internet World Wide web.

2. THE TELECOMMUNICATION SYSTEMS • Telecommunications system consists of hardware and software that transmit information from one location to another. • These systems can transmit text, data, graphics, voice, documents, or full-motion video information. • 2 basic types of signals, analog and digital. • ANALOG SIGNAL • Are continuous waves that transmit information by altering the characteristics of the waves. • DIGITAL SIGNAL • Digital Signal are discrete pulses that are either on or off, representing a series of bit ( 0s and 1s) • This quality allows them to convey information in a binary form that can be clearly interpreted by computers. 

3. THE TELECOMMUNICATION SYSTEMS COMMUNICATION PROCESSOR • Communications processors • are hardware devices that support data transmission and reception across a telecommunications system. These devices include modems, multiplexers, and front-end processors. • Modems. • The function of  modems is to convert digital signals to analog signals – a process called modulation – an analog signals to digital signals- a process called demodulation. • Modems are used in pairs. The modem at the sending end converts a computer’s digital information into analog signals or transmission over analog lines (for example, telephone lines) At the receiving end, another modem converts the analog signal back into digital signals for the receiving computer

4. THE TELECOMMUNICATION SYSTEMS COMMUNICATION PROCESSOR • Cable modems • are modems that operate over coaxial cable (for example, cable TV). • They offer high-speed access to the Internet or corporate intranets. • Cable modems use a shared line. • Therefore, when large numbers of users access the same modem, they can • slow down the access speed. • DSL modems • (digital subscriber line, discussed later in this Tech Guide) • operate on the same lines as voice telephones and dial-up modems. • Unlike dial-up, however, DSL signals do not interfere with voice service. Also, • DSL modems always maintain a connection, so an Internet connection is immediately • available.

5. THE TELECOMMUNICATION SYSTEMS COMMUNICATION PROCESSOR • Multiplexer • Is an electronic device that allows a single communications channel to carry data transmissions simultaneously from many sources. • Front-End Processor. • With most mainframe and minicomputers, the central processing unit(CPU) must communicate with multiple computers at the same time.

6. THE TELECOMMUNICATION SYSTEMS COMMUNICATIONS MEDIA & CHANNELS • For data to be communicated from one location to another, some form of pathway or medium must be used. These pathways are called communication channel.

7. THE TELECOMMUNICATION SYSTEMS COMMUNICATIONS MEDIA & CHANNELS • is used for almost all business telephone wiring • strands of copper wire twisted in pairs. • It is relatively inexpensive to purchase, widely • available, and easy to work with. • can be made relatively unobtrusive by running • it inside walls and floors, and above ceilings. • -relatively slow for transmitting data, it is subject • to interference from other electrical sources, • and it can be easily tapped by unintended • receivers for gaining unauthorized access to • data. • Twisted-Pair Wire.

8. THE TELECOMMUNICATION SYSTEMS COMMUNICATIONS MEDIA & CHANNELS • Coaxial Cable • consists of insulated copper wire. • much less susceptible to electrical • interference than is twisted-pair wire, • and it can carry much more data. • used to carry high-speed data traffic as • well as television signals (thus the term • cable TV). • coaxial cable is more expensive and • more difficult to work with than twisted- • pair wire.

9. THE TELECOMMUNICATION SYSTEMS COMMUNICATIONS MEDIA & CHANNELS • consist of thousands of very thin • filaments of glass fibers that transmit • information via light pulses generated • by lasers. • -The fiber-optic cable is surrounded by • cladding, a coating that prevents the • light from leaking out of the fiber. • -can transmit far more data, and they • provide greater security from • interference and tapping. • -Fiber-optic cable is typically used as the • backbone for a net-work, whereas • twisted-pair wire and coaxial cable • connect the backbone to individual • devices on the network • Fiber-optic cable

10. TYPES OF NETWORK • A computer network is a system that connects computers via communications media so that data can be transmitted among them. • networked computer systems enable organizations to be more flexible so they can adapt to rapidly changing business conditions. • enable companies to share hardware, computer applications, and data across the organization and among different organizations. • networks make it possible for geographically dispersed employees and work groups to share documents, ideas, and creative insights. • networks are a critical link between businesses and their customers.

11. TYPES OF NETWORK • Types of networks include (from smallest to largest) • a) Personal Area Networks (PANs) • b) Local Area Networks(LANs) • c) Metropolitan Area Networks (MANs) • d) Wide Area Networks (WANs) • . LOCAL AREA NETWORK (LANs) • Connects two or more devices in a • limited geographical region, • usually within the same building, • so that every device on the network can • communicate with every other device. • Allows the devices in a LAN to • communicate directly with each other • This medium is typically unshielded • twisted-pair wire (UTP)

12. TYPES OF NETWORK WIDE AREA NETWORK (WANs) • When businesses have to transmit and • receive data beyond the confines of the • LAN, they use WANs. • Wide area networks (WANs) are networks • that cover large geographic areas. • WANs typically connect multiple LANs. • Generally are provided by common • carriers such as telephone companies • and the international network of global • communications services providers. • WANs have large capacity, and they • typically combine multiple channels • (for example, fiber-optic cables, • microwave and satellite).

13. NETWORK FUNDAMENTALS • Computing devices that are connected to the network access and share the network to transmit and receive data. • These components are often referred to as “nodes” of the network. • Work together by adhering to a common set of rules that enable them to communicate with one another. • This set of rules and procedures that govern transmission across a network is a Protocol • 2 major protocols: the Ethernet and TCP/IP

14. NETWORK FUNDAMENTALS ETHERNET • A common LAN protocol is Ethernet. • Most large corporations use 10-gigabit Ethernet where the network provides data • transmission speeds of 10 gigabits per second. • 100-gigabit Ethernet is becoming the standard (100 billion bits per second). TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL • TCP/IP uses a suite of protocols, the main ones being the Transmission Control • Protocol (TCP) and the Internet Protocol (IP). • The TCP performs 3 basic functions: • (1) It manages the movement of packets between computers by establishing a • connection between the computers • (2) it sequences the transfer of pack ets. • (3) it acknowledges the packets that have been transmitted.

15. NETWORK FUNDAMENTALS TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL • The transmission technology that breaks up blocks of text into packets is called • packet switching. • Each packet carries the information that will help it reach its destination the • sender’s Internet Protocol (IP) address , the intended receiver’s IP address, • the number of packets in this message, and the number of this particular • packet within the message. • The application layer enables client application programs to access the other • layers and defines the protocols that applications use to exchange data. • One of these application protocols is the hypertext transfer protocol(HTTP) • which defines how messages are formulated and transmitted. • The transport layer provides the application layer with communication and • packet services. • This layer includes TCP and other protocols

16. NETWORK FUNDAMENTALS TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL • Internet layer is responsible for addressing, routing, and packaging data packets. The Internet protocol is one of the protocols in this layer.

17. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • What is a Topology? • The physical topology of a network refers to the configuration of cables, computers, and other peripherals. • 4 types of network topology are :- • Bus • Star • Ring • Tree

18. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • BUS • A linear bus topology consists of a main run of cable with a terminator at each end (See fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear cable.

19. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • BUS • Advantages of a Linear Bus Topology • Easy to connect a computer or peripheral to a linear bus. • Requires less cable length than a star topology. • Disadvantages of a Linear Bus Topology • Entire network shuts down if there is a break in the main cable. • Terminators are required at both ends of the backbone cable. • Difficult to identify the problem if the entire network shuts down. • Not meant to be used as a stand-alone solution in a large building.

20. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • STAR • A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator (See fig. 2). • Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable, however, it can also be used with coaxial cable or fiber optic cable.

21. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • STAR • Advantages of a Star Topology • Easy to install and wire. • No disruptions to the network when connecting or removing devices. • Easy to detect faults and to remove parts • Disadvantages of a Star Topology • Requires more cable length than a linear topology. • If the hub, switch, or concentrator fails, nodes attached are disabled. • More expensive than linear bus topologies because of the cost of the hubs, etc.

22. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • Tree • A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable (See fig. 3). Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.

23. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • Tree • Advantages of a Tree Topology • Point-to-point wiring for individual segments. • Supported by several hardware and software venders. • Disadvantages of a Tree Topology • Overall length of each segment is limited by the type of cabling used. • If the backbone line breaks, the entire segment goes down. • More difficult to configure and wire than other topologies.

24. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • Ring • In a ring topology, every node in the network is connected to two other nodes and the first and the last nodes are connected to each other. • The data that are transmitted over the network pass through each of the nodes in the ring until they reach the destination node. • In a ring network, the data and the signals that pass over the network travel in a single direction. • The dual ring topology varies in having two connections between each of the network nodes. • The data flow along two directions in the two rings formed thereby. • The ring topology does not require a central server to manage connectivity between the nodes and facilitates an orderly network operation. • But, the failure of a single station in the network can render the entire network inoperable. Changes and moves in the stations forming the network affect the network operation.

25. NETWORK FUNDAMENTALS NETWORK TOPOLOGY • Advantage of a Ring TopologyThe data being transmitted between two nodes passes through all the intermediate nodes. A central server is not required for the management of this topology.Disadvantages of a Ring TopologyThe failure of a single node of the network can cause the entire network to fail.The movement or changes made to network nodes affects the performance of the entire network.

26. Basic of the Internet and the World Wide Web THE INTERNET • The Internet is a worldwide collection of networks that links millions of business, government agencies, educational, and institutions. • An IP address is a number that uniquely identifies each computer or device connected to the Internet. • A domain name is the text version of an IP address. • A DNS server translates the domain name into its associated IP address. IP address 72. 14. 207. 99 Domain name www.google.com Specific computer The network

27. Basic of the Internet and the World Wide Web THE WORLD WIDE WEB • The World Wide Web or Web, consists of a worldwide collection of electronic • documents ( Web Pages - contain text, graphic, animation, audio & video ) • A Web Site is a collection of related Web Pages and associated item • (document and picture) • A Web Server is a computer that delivers requested Web Pages to your computer. • Web 2.0 refer to Web sites that provide a means for users to interact • (Social Networking, wikipedia, facebook) • A Web Browser, or Browser, allows users to access Web pages and web 2.0 • programs • Eg :- Internet Explorer , Firefox, Opera, Safari, Google Chrome

28. Basic of the Internet and the World Wide Web THE WORLD WIDE WEB • A home page is the first page that a web site displays. • Web pages provide links to other related web page • Downloading is the process of receiving information. • A web page has a unique address called a URL or Web address http://www.nps.gov/grsm/planyourvisit/wildlifeviewing.htm • Tabbed browsing allows you to open and view multiple Web pages in a single Web browser window. Protocol Domain name Path Web Page Name

29. Basic of the Internet and the World Wide Web OTHER INTERNET SERVICES • E-mail • Is the transmission of messages and files via a computer network. • An e-mail program allows you to create, send, receive., forward, store, print and delete e-mail messages. • Instant messaging (IM) • Is a real time Internet communication service. • One or more people online and then allow you to exchange messages / files / joint a privet chat room. • Chat is a real time typed conversation that takes place on a computer. • A Chat Room is a location on an Internet server that permits users to chat with each other. • VoIP ( Voice over IP ) • Enables users to speak to other users over the internet (also called internet telephony)

30. Basic of the Internet and the World Wide Web THE WORLD WIDE WEB • A newsgroup • is an online area in which users have written discussion about a • particular subject. • Typically requires a newsreader. • FTP (File Transfer Protocol) • Is an Internet standard that permits file uploading and downloading with • other computer on the internet. • Many operating systems include FTP capabilities. • FTP server is a computer that allows users to upload and or download file • using FTP.