Understanding science

10: Communications Technology - Extending the Limits

Network Structure and Innovation

Frank Kelly

The end-to-end arguments are a set of design principles that served as an architectural model for the Internet. They concern how application (or computer program) requirements should be met in a system. When a network is built, and specific applications are then built using the network (for example email or the World Wide Web), 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 core of the network.

End-to-end arguments, and the associated layering principle, gives rise to the 'hourglass' metaphor for the Internet architecture - an abstract bit-level network service at the hourglass' waist is provided by the TCP/IP protocol suite, and ensures the critical separation between an ever more versatile physical network infrastructure below the waist and an ever-increasing user demand for higher-level services and applications above the waist.

'IP over everything, and everything over IP' results in enormous robustness to changes below and above the hourglass' waist, and provides the flexibility needed for constant innovation and entrepreneurial spirit at the physical substrate of the network as well as in the design of services and applications.

Prof Frank Kelly is Chief Scientific Adviser to the Department for Transport and Professor of the Mathematics of Systems in the Department of Pure Mathematics and Mathematical Statistics, University of Cambridge

The title of this document is: Understanding science: 10: Communications Technology - Extending the Limits
URL: http://www.cam.ac.uk/about/scienceseminars/communications/structure.html

Seminar presented: 16/05/2003