CS 313 Introduction to Computer Networking Telecommunication Introduction

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

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

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

What is Computer Network? l An collection of AUTONOMOUS computers INTERCONNECTED by a single technology q. Interconnected: Able to EXCHANGE INFORMATION via transmission media ØMedia: copper wire, fiber optics, microwaves, communication satellites q. Autonomous: no master/slave relation ØNOT autonomous: § One computer can control another one § e. g. , a large computer with remote printers and terminals l Network of networks: internetwork 4

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

What is Telecommunication? l Components of data communication q. Sender, receiver, medium, message, and q. Protocol: set of rules governing data communication l Key elements of a protocol q. Syntax ØStructure/format q. Semantics ØMeaning q. Timing ØWhen and how fast 6

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

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

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

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

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

Client-Server Model 1 2 3 12

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

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

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

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

Metric Units l Computer storage size power of 2 qmega = 220=1, 048, 576 q 1 MB = 1 mega bytes = 1, 048, 576 bytes q 1 GB = l Computer networking speed not power of 2 qmega = 106 =1, 000 q 1 Mbps = 1 mega bits per second = 1, 000 bits / sec q 1 Gbps = 17