Effective bandwidths with priorities
Berger, A.W.; Whitt, W.
Networking, IEEE/ACM Transactions on
Volume 6, Issue 4, Aug 1998 Page(s):447 - 460
Digital Object Identifier 10.1109/90.720887
Summary:The notion of effective bandwidths has provided a useful practical
framework for connection admission control and capacity planning in
high-speed communication networks. The associated admissible set with a
single linear boundary makes it possible to apply
stochastic-loss-network (generalized-Erlang) models for capacity
planning. We consider the case of network nodes that use a
priority-service discipline to support multiple classes of service, and
we wish to determine an appropriate notion of effective bandwidths. Just
as was done previously for the first-in first-out (FIFO) discipline, we
use large-buffer asymptotics (large deviations principles) for workload
tail probabilities as a theoretical basis. We let each priority class
have its own buffer and its own constraint on the probability of buffer
overflow. Unfortunately, however, this leads to a constraint for each
priority class. Moreover, the large-buffer asymptotic theory with
priority classes does not produce an admissible set with linear
boundaries, but we show that it nearly does and that a natural bound on
the admissible set does have this property. We propose it as an
approximation for priority classes; then there is one linear constraint
for each priority class. This linear-admissible-set structure implies a
new notion of effective bandwidths, where a given connection is
associated with multiple effective bandwidths: one for the priority
level of the given connection and one for each lower priority level.
This structure can be used regardless of whether the individual
effective bandwidths are determined by large-buffer asymptotics or by
some other method
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