1. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.1 Computer Networks and Internets, 5e By Douglas E. Comer Lecture PowerPoints By Lami Kaya, LKaya@ieee.org

2. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.2 Chapter 2 Internet Trends

3. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.3 Topics Covered 2.1 Introduction 2.2 Resource Sharing 2.3 Growth of the Internet 2.4 From Resource Sharing to Communication 2.5 From Text to Multimedia 2.6 Recent Trends

4. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.4 2.1 Introduction This chapter –considers how data networking and the Internet have changed since their inception –gives a brief history of the Internet that highlights some of the early motivations –describes a shift in emphasis from sharing centralized facilities to fully distributed information systems Later chapters in this part of the text –continue the discussion by examining specific Internet applications –describe the communication paradigms available on the Internet –explain the programming interface that Internet applications use to communicate

5. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.5 2.2 Resource Sharing Early computer networks were designed when computers were large and expensive, and the main motivation was resource sharing –Networks were devised to connect multiple users each with a screen and keyboard, to a large centralized computer –Later networks allowed multiple users to share peripheral devices early networks were designed to permit sharing of expensive, centralized resources Department of Defense for Advanced Research Projects Agency (DARPA or ARPA) interested in finding ways to share resources (1960s) –Researchers needed powerful computers but these computers were very expensive the ARPA budget was insufficient to fund many computers –ARPA planned to interconnect all computers with a network and devise software that would allow a researcher to use whichever computer was best suited to perform a given task ARPA did the following to achieve the visionary work: –gathered some of the best minds available –focused them on computer network research –hired contractors to turn the designs into a working system: ARPANET The research turned out to be revolutionary

6. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.6 2.3 Growth of the Internet In less than 30 years –the Internet has grown from an early research prototype connecting a handful of sites to a global communication system –the rate of growth has been phenomenal Figure 2.1 illustrates the growth with a graph –The graph in Figure 2.1 uses a linear scale in which the y-axis represents values from zero through five hundred fifty million –Linear plots can be deceptive because they hide small details To understand the early growth rate –look at the plot in Figure 2.2, which uses a log scale –It shows that Internet has had exponential growth for over 25 years –Internet has been doubling in size every nine to fourteen months

7. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.7

8. 8 2.4 From Resource Sharing to Communication As it grew, the Internet changed in two significant ways: –First, communication speeds increased dramatically –Second, new applications arose that appealed to a broad cross- section of society –Internet is no longer dominated by scientists and engineers, scientific applications, or access to computational resources Two technological changes fueled a shift away from resource sharing to new applications: –Higher communication speeds enabled applications to transfer large volumes of data quickly –The advent of powerful, affordable, personal computers provided the computational power needed for complex computation and graphical displays, eliminating most of the demand for shared resources

9. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.9 2.5 From Text to Multimedia One of the most obvious shifts has occurred in the data being sent across the Internet Figure 2.3 illustrates one aspect of the shift –As the figure indicates, Internet communication initially involved textual data –By the 1990s, applications arose that allowed users to transfer images easily –By the late 1990s, users began sending video clips and full-motion videos Figure 2.4 illustrates that a similar transition has occurred in audio Multimedia characterizes data that contains a combination of text, graphics, audio, and video Much of the content available on the Internet now consists of multimedia Furthermore, quality has improved as higher bandwidths have made it possible to communicate high-resolution video and high-fidelity audio

10. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.10 2.5 From Text to Multimedia

11. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.11 2.6 Recent Trends New technologies and new applications continue to emerge Some of the most significant transitions have occurred as traditional communication systems –such as the voice telephone network and cable television, moved from analog to digital and adopted Internet technology –In addition, support for mobile users is accelerating Figure 2.5 lists some of the changes One of the most interesting aspects of the Internet –arises from the way that Internet applications change even though the underlying technology essentially remains the same Figure 2.6 lists types of applications that have emerged

12. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.12 2.6 Recent Trends

13. © 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.13 2.6 Recent Trends The availability of high-quality teleconferencing systems –such as Cisco's TelePresence, is significant for businesses because such systems permit meetings to occur without travel expense in many businesses, reducing travel expenses lowers costs significantly Some social networking applications such as –Facebook –Second Life –YouTube Social network apps are fascinating –because they have created new social connections - sets of people know each other only through the Internet –sociologists suggest that such applications will enable more people to find others with shared interests and will foster small social groups