tailieunhanh - Robustness and the Internet: Design and evolution

Despite the widespread use of the Internet and its impact on practically every segment of society, its workings remain poorly understood by most users. Nevertheless, more and more users take it for granted to be able to boot up their laptops pretty much anywhere (., cafes, airports, hotels, conference rooms) and connect to the Internet to use services as mundane as e-mail or Web browsing or as esoteric as musicor movie-distribution and virtual reality games. The few times the users get a glimpse of the complexity of the infrastructure that supports such ubiquitous communication are when they experience various \networking" problems (., the familiar \cannot connect". | Robustness and the Internet Design and evolution Walter Willinger and John Doyle March 1 2002 Abstract The objective of this paper is to provide a historical account of the design and evolution of the Internet and use it as a concrete starting point for a scientific exploration of the broader issues of robustness in complex systems. To this end we argue that anyone interested in complex systems should care about the Internet and its workings and why anyone interested in the Internet should be concerned about complexity robustness fragility and their trade-offs. 1 Introduction Despite the widespread use of the Internet and its impact on practically every segment of society its workings remain poorly understood by most users. Nevertheless more and more users take it for granted to be able to boot up their laptops pretty much anywhere . cafes airports hotels conference rooms and connect to the Internet to use services as mundane as e-mail or Web browsing or as esoteric as music-or movie-distribution and virtual reality games. The few times the users get a glimpse of the complexity of the infrastructure that supports such ubiquitous communication are when they experience various networking problems . the familiar cannot connect message or unacceptably poor performance because diagnosing such problems typically exposes certain aspects of the underlying network architecture how the components of the network infrastructure interrelate and network protocols standards governing the exchange of data . Consider for example a user sitting in a cafe and browsing the Web on her laptop. In terms of infrastructure a typical scenario supporting such an application will include a wireless access network in the cafe an Internet service provider that connects the cafe to the global Internet intermediate service providers that agree to carry the user s bytes across the country or around the globe through a myriad of separately administered autonomous domains and another service .