Introduction to Networking

1. Introduction to Networking Data Communications and Networks Mr. Greg Vogl Uganda Martyrs University Lecture 2, 19 March 2003

2. Overview • Definitions • LAN/WAN, Internet/Intranet, Client/Server/Peer • Local Area Networks • Types, components, topologies, resources • Benefits/costs, design questions • Wide Area Networks • Connecting networks • Models, components • Benefits/costs Data Communications and Networking: Introduction to Networking

3. LAN vs. WAN • Network • connection of computers • so they can exchange data and share resources • LAN: Local Area Network • link computers within a small geographic area, such as a building or a group of buildings • uses direct cables (or wireless signals) • WAN: Wide Area Network • powerful computers linked across large distances • uses wires, cables, electromagnetic signals, etc. Data Communications and Networking: Introduction to Networking

4. Internet vs. Intranet • Internet • a global network of networks that connects millions of computers • Intranet • a private version of the Internet, using Web browsers and server on LANs Data Communications and Networking: Introduction to Networking

5. Client-Server vs. Peer-to-Peer • Server • computer that provides access to shared resources • e.g. printers and disks • Client • computer accessing shared resources on servers • Client-Server Network • one or more computers dedicated as servers • many clients • Peer-to-Peer Network • shares resources among a few “equal” computers Data Communications and Networking: Introduction to Networking

6. Client-Server Networks • Dedicated server computers provide resources • Client computers access server’s resources • Centralised administration and maintenance • Requires highly trained network administrator • Security is strong, user and group-based • Performance depends on server capabilities • Works well for large networks (>10 computers) Data Communications and Networking: Introduction to Networking

7. Peer-to-Peer Networks • Each computer acts as both client and server • No server computer or network OS required • Distributed administration and maintenance • Users must act as administrators of their PCs • Security is weak, resource-based • Performance depends on peer workstations • Best for small network of <10 advanced users Data Communications and Networking: Introduction to Networking

8. LAN Hardware Components • Computers: two or more, maybe a server • Hub: at least one, with one port per computer • NICs: Network Interface Cards/Adapters • One installed in each computer, connects to hub • Cables: to connect computers • Unshielded twisted pair (UTP), co-axial, fibre optic • Peripherals: to be shared on the network • Printers, scanners, disk drives, modems, etc. Data Communications and Networking: Introduction to Networking

9. Network Operating Systems • Peer-to-Peer • Windows 3.11/95/98/Me • Windows NT/2000 Pro • Client-Server • Windows NT/2000 Server • Novell Netware • UNIX/Linux Data Communications and Networking: Introduction to Networking

10. Terminology • Topology • physical layout of network connections • Protocol • standard of how devices communicate • Interface • connection to allow communication • Bandwidth or Data Transfer Rate • data speed in bits per second Data Communications and Networking: Introduction to Networking

11. Network Topologies: Star • Each computer is attached to central hub • Easy to add/remove computers • connect cable to computer and to hub port • Bad cable only isolates one computer • Hub is single point of failure • Most popular for LANs Data Communications and Networking: Introduction to Networking

12. Network Topologies: Bus • Each computer attached to the network cable • Cheapest (no hub required) • Difficult to add/remove computers • Difficult to troubleshoot bad connections • Broken connection partitions network • Sometimes used for small LANs Data Communications and Networking: Introduction to Networking

13. Network Topologies: Ring • Computers connected in a closed loop • Token of data passed around in one direction • Often logical ring but physical star • Multi-station access unit (MSAU) hub • Fibre distributed data interface (FDDI) • Used to connect high-speed networks Data Communications and Networking: Introduction to Networking

14. Sharing Resources • Resources that can be shared include: • hardware (disks, printers, scanners, fax...) • software (programs) • data (files, folders) • servers: file, print, directory, mail, fax • Access to resources can be restricted: • to certain users or groups (with NT Server) • read-only • password-protected Data Communications and Networking: Introduction to Networking

15. Network Neighborhood • Accessible through Desktop, My Computer or Windows Explorer • Shows computers in local area network • Computers are grouped into workgroups or domains • Each computer lists its shared resources Data Communications and Networking: Introduction to Networking

16. LAN Benefits • Shared resources (hardware, software, data) • Economy of scale: low cost per user/computer • Communication and information exchange • Email, Web browsing, conferencing, scheduling, etc. • Centralised, remote administration • Install, backup, monitor, cleanup, troubleshoot Data Communications and Networking: Introduction to Networking

17. LAN Costs • Network hardware • Network OS • Communications software • Network design and development • Administration and maintenance • Training • Security Data Communications and Networking: Introduction to Networking

18. Client/Server Costs • Operations and support • Application development • Hardware, software • Network installation, maintenance • Education and training Source: Laudon & Laudon, Table 9.5 Data Communications and Networking: Introduction to Networking

19. Networking Problems • Connectivity problems • Loss of management control • Ogranizational changes required • Hidden costs • Network reliability and security Source: Laudon & Laudon, Table 9.4 Data Communications and Networking: Introduction to Networking

20. Network Design Questions • Who are your users? • What are their individual and group goals? • What are their computing/information needs? • What types of uses will the computers have? • What software do they need to use? • What hardware is needed to run the software? • What data traffic is the network likely to have? Data Communications and Networking: Introduction to Networking

21. Network Design Questions (cont’d) • Is a dedicated server needed? • What server specifications will be needed? • Is a network operating system needed? • What backup media should be used? • What shared resources should be available? • How should access to resources be restricted? • Other security problems/measures? Data Communications and Networking: Introduction to Networking

22. Connecting Networks • Intranet • Private version of Internet; protected by firewall • Extranet • Intranet accessible to authorised outsiders • Virtual Private Network • Secure Internet connection for data transmission • Internetworking • Linking separate networks • Enterprise Network • A network to link a company’s resources Data Communications and Networking: Introduction to Networking

23. Connectivity Models • TCP/IP model • Developed by US Defense Dept; used on Internet • Five layers: physical, net, IP, TCP, application • Every Internet site has an IP address • Open Systems Interconnect (OSI) model • Developed by International Standards Org. • for linking different types of computers, networks • Seven layers, idealised, rarely implemented fully • public, nonproprietary, portable Data Communications and Networking: Introduction to Networking

24. WAN Hardware Components • Gateway • Connects different types of networks by translating • Bridge • Connects similar networks • Router • Intelligently directs traffic to appropriate networks • Routes data packets through connected LANs/WAN Data Communications and Networking: Introduction to Networking

25. Communications Hardware • Telephones, modems, PBX, voice mail, Facsimile/Fax • Information digitised, transmitted through phone lines • Cellular (mobile) phones, pagers • Wireless communication using radio waves • Videoconferencing • Computers, video cameras, microphones, speakers • Global Positioning System (GPS) • Satellites determine position of devices • Used for tracking and navigation of vehicles, etc. Data Communications and Networking: Introduction to Networking

26. Communications Software • Personal Info. Management e.g. MS Outlook • Address book, notes, messages, task lists • Scheduling (calendar, meetings, appointments, etc.) • Groupware e.g. Lotus Notes • Scheduling, e-mail, conferencing, editing, databases • Project Management e.g. MS Project • Planning, scheduling, analysing • Tasks, events, resources, costs • Other e.g. dial-up networking, terminal emulators • Connect to computers/networks, transfer files, run programs Data Communications and Networking: Introduction to Networking

27. Internet Components • Network hardware and operating systems • to send/receive information over long distances • Web pages • hypertext documents (linked together) • multimedia (pictures, sounds, videos etc.) • Web server • Computer that stores web documents • Web clients • Browser software to retrieve and view web pages • mail, newsgroups, chat, conferencing, file transfer Data Communications and Networking: Introduction to Networking

28. Internet Access • Internet Service Provider (ISP) • Organisation with direct Internet connection • Sells Internet connections to businesses/individuals • Providers of online services: AOL, MSN, Prodigy • Internet Café • Pays ISP to connect its LAN to Internet • Allows individuals to use Internet for short periods Data Communications and Networking: Introduction to Networking

29. Internet Benefits to Organisations • Connectivity and global reach • Reduced communication costs • Lower transaction costs • Reduced agency costs • Interactivity, flexibility, customization • Accelerated distribution of knowledge Source: Laudon & Laudon, Table 10.2 Data Communications and Networking: Introduction to Networking

30. Intranet Benefits • Easy to build and run; inexpensive • Easy to update, expand or contract • Easy to access by different PCs/devices • Easy to use (Web browser is familiar) • Multimedia, interactive, responsive • Reduced info. distribution costs Source: Laudon & Laudon, Table 10.6 Data Communications and Networking: Introduction to Networking