An Evaluation of Distributed Parallel Reservations in Wavelength-Routed Networks

Distributed lightpath provisioning is expected to play a key role in next-generation WDM optical networks. A major challenge in distributed lightpath provisioning is the potentially significant degradation of network blocking performance caused by outdated link-state information, occurring especially under traffic with short average durations of connections. To address this problem, various parallel reservation schemes have been proposed, with the common feature of applying multiple capacity-search and/or reservation operations executed simultaneously. In this paper, we evaluate the performance of these distributed parallel reservation schemes in wavelength-routed networks. Specifically, we develop general yet accurate analytical models to provide insights into the behavior of the different schemes. We also conduct extensive simulation study. Numerical results show that by using simple parallel reservation schemes, in particular through multiple reservations on several different routes, blocking probabilities caused by outdated link-state information can be drastically lowered and network performance can be significantly improved. The tradeoff between control traffic loads and network blocking performance is also evaluated.