1. Chi-Cheng Lin, Winona State University CS 313 Introduction to Computer Networking & Telecommunication Introduction – Part I

2. 2 Topics l Introduction l Metric Units l Network Hardware l Network Software l Reference Models l Example Networks l Standards and Standards Organizations

3. 3 Introduction l First two decades of computing  Highly centralized computer systems l Now  A large number of SEPARATE but INTERCONNECTED computers  Computer networks

4. 4 What is Computer Network? l An collection of AUTONOMOUS computers INTERCONNECTED by a single technology  Interconnected: Able to EXCHANGE INFORMATION via transmission media  Media: copper wire, fiber optics, microwaves, communication satellites  Autonomous: no master/slave relation  NOT autonomous:  One computer can control another one  e.g., a large computer with remote printers and terminals l Network of networks: internetwork

5. 5 What is Telecommunication? l What is data communication?  Exchange of data between two devices via some form of transmission media  Data are represented by bits – 0s and 1s l What is telecommunication?  Exchange of information over distance using electronic equipment

6. 6 What is Telecommunication? l Components of data communication  Sender, receiver, medium, message, and  Protocol: set of rules governing data communication l Key elements of a protocol  Syntax  Structure/format  Semantics  Meaning  Timing  When and how fast

7. Data Communication l Components of data communication 7 SenderReceiver Medium Message Step 1: … Step 2: … : Protocol Step 1: … Step 2: … : Protocol

8. 8 Distributed System vs. Computer Network l Distributed system  TRANSPARENCY  A collection of independent computers appear as a single coherent system  Single model/paradigm to users  Middleware on top of OS  Example? l Computer network  No such coherence, model, middleware  Machines visible to users  Users log onto remote machines

9. 9 Distributed System vs. Computer Network l A distributed system is a SOFTWARE system built on top of a network l Distinction between network and distributed system  Software (especially OS) rather than hardware l However, considerable overlap between the two subjects

10. 10 Uses of Computer Networks l Business applications  Resource sharing  Communication medium  E-commerce l Client-server model  Client requests, server performs & then replies  Example?

11. 11 Business Applications of Networks l A network with two clients and one server.

12. 12 Client-Server Model 1 2 3

13. 13 Uses of Computer Networks l Home applications  Access to remote information  On-line publishing, digital library, WWW  Person-to-person communication  Email, instant messaging, videoconferencing, Internet phone, E-learning, multi-person messaging  Interactive entertainment  Video on demand (VOD), games  E-commerce  Home shopping, electronic banking and investment, on-line auction  Social network applications  Collaborative content creation

14. 14 Home Network Applications (2) l Besides client-server model  Peer-to-peer system: there are no fixed clients and servers.

15. 15 Mobile Users l Notebooks, PDAs, cellular phones l Smart phones: convergence of telephones and Internet l M-commerce, texting l Sensor networks l Wearable computers l Wireless networking and mobile computing

16. 16 Metric Units l The principal metric prefixes l b: bit l B: byte = 8 bits

17. 17 Metric Units l Computer storage size power of 2  mega = 2 20 =1,048,576  1 MB = 1 mega bytes = 1,048,576 bytes  1 GB = l Computer networking speed not power of 2  mega = 10 6 =1,000,000  1 Mbps = 1 mega bits per second = 1,000,000 bits / sec  1 Gbps =