Marjory S. Blumenthal Computer Science and Telecoms Board, NRC David D. Clark

1. W02 / COSC 6590A / Advanced Computer NetworksPaper PresentationRethinking the Design of Internet:The End-to-end Arguments vs. the Brave New World Marjory S. Blumenthal Computer Science and Telecoms Board, NRC David D. Clark MIT Lab for Computer Science Appeared in ACM Transactions on Internet Technology, Vol. 1, No.1 Aug.2001, p70-109 Presented by Yanling Wang Computer Science, York University, Toronto

2. Outline • Communications & Internet histories • End-to-end arguments • New requirements in today’s communication • Identify a range of possible solutions that might be used to meet these requirements • Look at the implications for the rights and responsibilities of the various parties that comprise the Internet • Describe the range of emerging players • Conclusions • Picture of future Internet

3. History of Communications • 1500's Chief noblemen (e.g. the Pope) possessed more than 100 messengers • 1544 Holey Roman Empire granted monopoly to the Thurn and Tassis family -> Deutche Bundespost • 1840'sTelegram The first digital method of electronic communication • 1876 Bell telephone developed by accident! AT&T owner of the patent. • 1896Telephone dial invented by Almon Strowger, a Kansas City undertaker. Feared he was loosing business to a competitor whose wife happened to be a local switchboard operator. First place to use it was La Porte, Indiana. Also developed the 'step' exchange still in use. • 1890's Loading coil developed to allow 'long-distance' calls. • 1920's Telephone companies started using Strowgers technology as patent ran out.1920's AT&T developed way of putting many calls on one line ('analogue carrier' technology). Continued to be develop up until 1970's • 1962 First communications satellite launched • 1970'sFiber optictechnology • 1980'sDigital technologies

4. History of Internet(INTERnational NETwork / INTERconnected NETwork) 1957 Sputnik Launched 1969 ARPnet: in US 1972 ARPnet: Report Generated 1973 ARPnet: Norway & England 1974 Transmission Protocol 1983 TCP/IP 1984 MILNET & DNS 1985 1st Internet Domain 1986 Online Forum & Firewall 1990 ARPnet off, Internet On 1991 Info. Retrieved from Server 1992 Hypertext  WWW 1993 Web Browsers  Surfing 1994 Size Double/Year 1999 ISPs: Internet Free Access The figure was copied from the Internet.

5. Internet Design Principles:End-to-end Arguments • 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 systems. Therefore, providing that questioned function as a feature of the communications systems itself is not possible. • This suggests that specific application level functions usually can not, and preferably should not, be built into the lower levels of the system-the core of the network. • Result in: • Function migrates to the end node. • Network should be “as transparent as technology permits”.

6. User User Router Router User Router User Router The Internet User A simple View of Internet Router

7. Advantages of the End-to-end Arguments • User empowerment • Run what you please • Flexibility in the face of unknown applications • A network to glue computers together • Lower cost in core of network • Eliminate special features • Rely on edge-node equipment • More robust applications • No unexpected failures of third party nodes • Moving application specific functions out of the core of the network • Complexity of the core network reduced • Generality in the network increases the chances that a new application can be added without having to change the core of the network • Applications do not have to depend on the successful implementation and operation of application specific services in the network

8. Examples of Emerging Requirements in Today’s Internet • Operation in an untrustworthy world • Imply more mechanism in the center of the network to enforce “good” behavior • More demanding applications (streaming audio & video, etc.) • More sophisticated internet service is needed to assure each data stream a specified throughput • ISP services differentiation • ISP-specific intermediate servers • The rise of third-party involvement • Less sophisticated users What do these requirements really imply? • World is becoming more complex • What is needed is a set of principles that interoperate with each other, some built on the end-to-end model, and some on a new model of network-centered function.

9. What About in the Brave New World? • The End-to-end model does not empower: • ISPs: want to sell services, add value, and make money. New network services, protection, control of applications/content, accounting • Rights holders • Governments: control of content, taxation, consumer protection, law enforcement • Employers • It empowers: • Only certain application makers

10. End-to-end Argument Functionsat Network level - “in” the Network • Adding functions to the core of the network • Firewalls • Traffic filters • Network address translation elements • Design issues in adding mechanism to the core of the network • Imposing a control element into the path of communication • Revealing or hiding the content of message • Labels on information

11. End-to-end Argument Functionsat Application Level - “on” the Network • Application-level services being employed to augment or modify application behavior • Anonymizing message forwarders: It is critical that the user construct the route, the ISP, or any other third party should not be able to determine the path directly. Third party removes the possible identification in the messages. • Helpful content filtering • Content caches • More complex application design-using trusted third parties • Public-key certificate: user can create a public key and give it to others, to enable communication with that user in a protected manner. Third party issues a public key certificate and manages the stock of such certificates.

12. User User User User User The Internet User User A Complex View of the Internet Backbone ISP Backbone ISP Little ISP Campus Corp Backbone ISP Little ISP User User

13. Addressing Where We Are • The rise of the new players • Governments • ISPs • Industry consolidation • Institutional providers of Internet services: corporations, schools, and non-profit organizations • International nature of the Internet • The erosion of trust • May be most fundamental for transforming the Internet • Use trusted third parties • Both end-points and third parties may wish to interpose intermediate elements into a communication to achieve their objectives of verification and control ¿ But, are third parties actually trustworthy? Or are end-points talking to the third party they think they are? • Rights and responsibilities • The end-to-end design of the Internet gives the user considerable power in determine what applications he/she chooses to use • Today the Internet places few limits on what groups of consenting end-nodes do in communicating across the network ¿ How can the desire for privacy and anonymity be balanced against the need for accountability, given the freedom of action that the end-to-end arguments imply?

14. Moving Forward • Labels • A comprise between autonomy and visibility of action • Distinction between private and public communication • Accept that private communication is not restricted • Focus on communication to the public • New principles for application design • Do not force an end-node implementation • Allow the user to select an alternative • A more sophisticated form of empowerment • Tolerance for experimentation

15. Conclusions • Elements that implement functions that are invisible or hostile to end-to-end application, in general, have to be “in” the network • Multiple forces seem to promote change within the Internet that may be inconsistentwith the end-to-end arguments • Less work by consumers may imply less control over what they can do on the Internet and who can observe what they do • Lost of trust • Trust can be supported by systematic labeling of content • It is no longer the single creative person in the garage, but the startup with tens of millions of dollars in backing that is doing the group innovation • Commercial investment will go elsewhere, in support of short-term opportunities better met by solutions that are not end-to-end, but based on application-specific servers and services “inside” the network

16. Picture of Future Internet • It is possible that we will see, not a sudden change in the spirit of the Internet, but a slow ossification of the form and function. • In time some new network will appear, perhaps as an overlay on the Internet, which attempts to re-introduce a context for unfettered innovation • It is premature to predict the final form. What we can do is to push in ways that tend toward certain outcomes

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