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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.
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