Introduction to Computer Networks

1. Introduction to Computer Networks Chapter 1

2. Chapter Objectives • Explain the need of networks • Explain history of computer networks (ARPANET) • Explain the types of computer networks • Explain Client/Server configuration • Explain layers of OSI model • Explain network selection criteria • Application • Explain Standards Organizations

3. Computer Network • Interconnection of two or more computers and peripherals • Allows user to share and transfer information

4. Types of Computer Networks • Networks are classified depending on the geographical area covered by the network

5. Local Area Network (LAN) - I • Covers a small area • Connects computers and workstations covering a local area like, office or home

6. Local Area Network (LAN) - II • Advantages of LAN: • Improves productivity due to faster work • Provides easy maintenance • New systems can be installed and configured easily • Disadvantages of LAN: • Limited number of systems can only be connected • Cannot cover large area • Network performance degrades as number of users exceeds

7. Types of LAN • LANs are classified depending on the techniques used for data sharing

8. Campus Area Network (CAN) • Made up of multiple LANs within limited area • Connects different LANs in a campus

9. Metropolitan Area Network • Interconnects networks within a city • Supports data and voice transmission

10. Wide Area Network • Covers a wide geographical area which includes multiple computers or LANs e.g. Internet

11. Case Study - I MoneyMaker is a bank having its registered office at Delhi. It has branches at Mumbai, Chennai, Hyderabad and Bangalore. The operating departments in the bank are Finance, Insurance, Loan, IT, Marketing, Customer Service and HR. MoneyMaker bank uses LAN as their computer network for each department. All the branches of the bank from different cities are connected through WAN. The bank is expanding and decided to open its branches at different locations in the city.

12. Problem Determine which type of network to be used within a city

13. Suggested Solution Use LAN computer network for each department in the new branch. MAN can be used for connecting the different branches of the bank within the city

14. Client/Server Configuration • Consists of two elements, Client and Server • Server: • A centralized element which provides resources to client • Manages data, printers or network traffic • Client: • Manages local resources used by users such as monitor, keyboard, CPU and peripherals

15. Open System Interconnection (OSI) Model - I • Also known as ISO-OSI Reference Model • Developed by International Organization for Standardization (ISO) • Describes flow of information from one computer to another • Consists of seven layers

16. Open System Interconnection (OSI) Model - II

17. Network Selection Criteria • Helps to improve network functionality

18. Case Study - II The Customer Service department of MoneyMaker bank provides online services to the customers. At Hyderabad branch, the Customer Service department network is not functioning properly. So the bank has decided to build an alternative network for that department .

19. Problem Selecting the network criteria

20. Suggested Solution Decide network type and configuration, number of users, speed of the network, hardware to be used, operating system to be installed and anti-virus software

21. Standards Organizations • Also known as Standards Development Organization (SDO) • Develop, maintain, improve and revise standards • Classified as: • International organozations – International Organization for Standardization (ISO) • National organozations – American National Standards Institute (ANSI) • Regional organozations – Euro-Asian Council for Standardization (EASC)

22. Summary - I • Computer network enables the user to share data and network resources • Network allows remote users to communicate with each other • Computer networks are divided into LAN, CAN, MAN and WAN depending on the coverage area • LAN is a small network and easy to create • Client/Server configuration also called as two-tier architecture, consist of two nodes, client and server

23. Summary – II • OSI model consists of seven layers and provides standards for computer communication • Physical layer is responsible for actual transmission of bits over the medium • Data Link layer is responsible for node to node delivery of frames • Network layer is responsible for end to end delivery of packets, and routing

24. Summary - III • Transport layer is responsible for end to end delivery of the entire message • Session layer is responsible for establishing, managing and terminating sessions • Presentation layer is responsible for translation, encryption and data compression • Application layer is responsible for providing access to the network

25. Summary - IV • Performance, reliability and security are the network selection criterion which enables to choose efficient network • Standards organizations like ISO and ANSI develop technical and non- technical standards • International standards organizations are International Standard Organization (ISO), International Telecommunication Union (ITU), Institute of Electrical and Electronics Engineers (IEEE) and World Wide Web Consortium (W3C)