How much the wavelength dimensioning methods and a tightened QoS provision impact on the dynamic WDM optical networks capacity?

摘要

This article gives an insight on the importance to assign a different capacity to each network link and to tighten the Quality of Service (QoS) provision in the network, in dynamic WDM Optical Networks with wavelength continuity constraints. In the text, several examples illustrate the performance of different strategies. The usual procedure to compute the number of wavelengths of each network link consists of choosing the same capacity to each link on the network. This decision is selected, in most cases, by simplicity and simulation limitations. Notwithstanding, there are no technical motives to force a uniform capacity on the network. In consequence, we analyze the impact on the network capacity of designating the minimum amount of wavelengths to each network link, while satisfying each user QoS requirement. Moreover, despite the chosen dimensioning strategy, it is usual to offer a much better QoS than requested for some users, with the corresponding waste of resources. We can amend this issue by limiting which wavelengths are available to each user according to its particular QoS constraint. This technique, known as Wavelength Grouping, seeks to provide to each user a QoS level closer to the one defined in the Service Level Agreement. By doing so, it is possible to reduce the network capacity needed to allow communication to its user, or diminishing the network blocking probability for a given wavelength capacity. In spite of the usual approach, in this work, we demonstrate that a non-uniform dimensioning strategy and a tighten QoS provision allows to save significant networks capacity, while simultaneously provisioning to each user the QoS established in its Service Level Agreement. This fact is very relevant nowadays, where an impending capacity crunch in optical networks is an important issue.