3rd International Week on Management of Networks and Services End-to-End Virtualization of Networks and Services Manweek 2007, October 29-November 2, San José, CA, USA
1University of Twente, Netherlands 2University of Amsterdam, Netherlands
Abstract. Link dimensioning is generally considered as an effective and (operationally)
simple mechanism to meet (given) performance requirements. In practice,
the required link capacity C is often estimated by rules of thumb, such as
C = d*M, where M is the (envisaged) average traffic rate, and d some (empirically
determined) constant larger than 1. This paper studies the viability of this
class of ‘simplistic’ dimensioning rules. Throughout, the performance criterion
imposed is that the fraction of intervals of length T in which the input exceeds
the available output capacity (i.e., C*T) should not exceed epsilon, for given T and epsilon.
We first present a dimensioning formula that expresses the required link capacity
as a function of M and a variance term V(T), which captures the burstiness
on timescale T. We explain how M and V(T) can be estimated with low measurement
effort. The dimensioning formula is then used to validate dimensioning
rules of the type C = d*M. Our main findings are: (i) the factor d is strongly
affected by the nature of the traffic, the level of aggregation, and the network infrastructure;
if these conditions are more or less constant, one could empirically
determine d; (ii) we can explicitly characterize how d is affected by the ‘performance
parameters’, i.e., T and epsilon.
