Mathematics of Information Technology and Complex Systems Complex Adaptive Networks for Computing and Communication (CANCCOM)


Project Highlights


Team Members

Partner Organizations







    - Network Calculus (NetCal)

Led by Prof. Amit Bose.

Network Calculus (NetCal) is a collection of mathematical tools based on Min-Plus algebra, which applies to deterministic queuing systems found in communication networks. It is a relatively new field. The earliest paper on the topic dates from 1991. There are only two books on the subject, both published after 2000. NetCal can be used, for example, to develop the computations for delays used in the IETF guaranteed service, to understand why re-shaping delays can be ignored in shapers or spacer-controllers, to develop a common model for schedulers and to develop deterministic effective bandwidth.

Netcal has two key advantages. Firstly, it is a method of calculation, not simulation. Hence the results are obtainable (once the equations can be written down) with much less effort. This avoids dealing with simulation software. Secondly, Netcal is based on determining a guaranteed bound on worst performance. Although NetCal has been used successfully in understanding the performance of a network as a whole, it has not yet been applied to small scale systems, such as within a router. The reasons for this are threefold. First, the tools needed to understand the details of how to model a router are not yet completely available. Second, the presently available tools are new and appear to be very absract. To justify a practitioner's investment of time and effort to understand these tools, a proof of concept is needed. Third, NetCal provides a worst case bound that may be overly pessimistic in some cases. This implies that there is more work to be done on NetCal itself to tighten the bounds obtained by its techniques.

                                                        Maintained by Jeyanthi Hall     Copyrights@CANCCOM 2003    Last modified: Monday October 18, 2004