Departmental Papers (CIS)

Date of this Version

February 2003

Document Type

Conference Paper


Postprint version. Published in Computer Systems: Theory, Technology and Applications: A Tribute to Roger Needham, New York : Springer, 2004, pages 273-277. Proceedings of the meeting, 'Roger Needham: 50 and 5', held 17 February 2003.


The design space for network architectures can be conveniently described as a 3-tuple of <Application Requirements, Protocol Elements, Network Conditions>. Application requirements can range from reliability and small message inter-arrival delay to communications secrecy. Protocol elements include acknowledgements and error-correcting codes, timers and a variety of cryptographic transformations. Network conditions include delay, delay variance, loss rates, bit error rates (BERs), topology, and available bandwidths. For any given triple, and in particular for a choice of application and requirements, there are assumptions about operating conditions made, and protocol elements selected to meet the application requirements under these conditions.



Date Posted: 12 September 2005