FYI: At 10/5/01 02:37 AM, David Farber wrote: >>http://www.ana.lcs.mit.edu/anaweb/PDF/Rethinking_2001.pdf >> >>"Rethinking the design of the Internet: >>The end to end arguments vs. the brave new world" >> >>Marjory S. Blumenthal Computer Science & Telecommunications Board, NRC >>[EMAIL PROTECTED] >>David D. Clark M.I.T. Lab for Computer Science [EMAIL PROTECTED] >> >>A version of this paper to appear in the ACM Transactions on Internet >>Technology >>A version also to appear in Communications Policy in Transition: The >>Internet and Beyond, >>edited by Benjamin Compaine and Shane Greenstein, MIT Press, Sept. 2001 >> >>Abstract >> >>This paper looks at the Internet and the changing set of requirements >>for the Internet that are emerging as it becomes more commercial, more >>oriented towards the consumer, and used for a wider set of purposes. We >>discuss a set of principles that have guided the design of the Internet, >>called the end to end arguments, and we conclude that there is a risk >>that the range of new requirements now emerging could have the >>consequence of compromising the Internet's original design principles. >>Were this to happen, the Internet might lose some of its key features, >>in particular its ability to support new and unanticipated applications. >>We link this possible outcome to a number of trends: the rise of new >>stakeholders in the Internet, in particular Internet Service Providers; >>new government interests; the changing motivations of the growing user >>base; and the tension between the demand for trustworthy overall >>operation and the inability to trust the behavior of individual users. >> >>Introduction >> >>The end to end arguments are a set of design principles that >>characterize (among other things) how the Internet has been designed. >>These principles were first articulated in the early 1980s, and they >>have served as an architectural model in countless design debates for >>almost 20 years. >> >>The end to end arguments concern how application requirements should be >>met in a system. When a general purpose system (for example, a network >>or an operating system) is built, and specific applications are then >>built using this system (for example, e-mail or the World Wide Web over >>the Internet), there is a question of how these specific applications >>and their required supporting services should be designed. The end to >>end arguments suggest that specific application-level functions usually >>cannot, and preferably should not, be built into the lower levels of the >>system-the core of the network. The reason why was stated as follows in >>the original paper: >> >>"The function in question can completely and correctly be implemented >>only with the knowledge and help of the application standing at the >>endpoints of the communications system. Therefore, providing that >>questioned function as a feature of the communications systems itself is >>not possible." >> >>In the original paper, the primary example of this end to end reasoning >>about application functions is the assurance of accurate and reliable >>transfer of information across the network. Even if any one lower level >>subsystem, such as a network, tries hard to ensure reliability, data can >>be lost or corrupted after it leaves that subsystem. The ultimate check >>of correct execution has to be at the application level, at the >>endpoints of the transfer. There are many examples of this observation >>in practice. >> >>Even if parts of an application-level function can potentially be >>implemented in the core of the network, the end to end arguments state >>that one should resist this approach if possible. There are a number of >>advantages of moving application-specific functions up out of the core >>of the network and providing only general-purpose system services there. >> >>o The complexity of the core network is reduced, which reduces costs and >>facilitates future upgrades to the network. >> >>o Generality in the network increases the chances that a new application >>can be added without having to change the core of the network. >> >>o Applications do not have to depend on the successful implementation >>and operation of application-specific services in the network, which may >>increase their reliability. >> >>Of course, the end to end arguments are not offered as an absolute. >>There are functions that can only be implemented in the core of the >>network, and issues of efficiency and performance may motivate >>core-located features. Features that enhance popular applications can be >>added to the core of the network in such a way that they do not prevent >>other applications from functioning. But the bias toward movement of >>function "up" from the core and "out" to the edge node has served very >>well as a central Internet design principle. >> >>As a consequence of the end to end arguments, the Internet has evolved >>to have certain characteristics. The functions implemented "in" the >>Internet-by the routers that forward packets-have remained rather simple >>and general. The bulk of the functions that implement specific >>applications, such as e-mail, the World Wide Web, multi-player games, >>and so on, have been implemented in software on the computers attached >>to the "edge" of the Net. The edge-orientation for applications and >>comparative simplicity within the Internet together have facilitated the >>creation of new applications, and they are part of the context for >>innovation on the Internet. >> >>Moving away from end to end >> >>For its first 20 years, much of the Internet's design has been shaped by >>the end to end arguments. To a large extent, the core of the network >>provides a very general data transfer service, which is used by all the >>different applications running over it. The individual applications have >>been designed in different ways, but mostly in ways that are sensitive >>to the advantages of the end to end design approach. However, over the >>last few years, a number of new requirements have emerged for the >>Internet and its applications. To certain stakeholders, these various >>new requirements might best be met through the addition of new mechanism >>in the core of the network. This perspective has, in turn, raised >>concerns among those who wish to preserve the benefits of the original >>Internet design. >> >>Continued at: >> >>http://www.ana.lcs.mit.edu/anaweb/PDF/Rethinking_2001.pdf > >For archives see: http://www.interesting-people.org/ +++ Jay Fenello, Internet Coaching http://www.Fenello.com ... 678-585-9765 http://www.YourWebPartner.com ... Web Support http://www.AligningWithPurpose.com ... for a Better World ----------------------------------------------------------- "A new civilization is emerging in our lives, and blind men every�where are trying to suppress it." -- Alvin Toffler
