Efficient scheduling strategies for dynamic WDM networks with set-up delay tolerance

Emerging, on-demand applications (e.g., ultra-high definition TV, grid computing, e-health, digital cinema, etc.) will dominate the next generation optical networks. Dynamic on-demand provisioning of optical channels is advocated as a promising solution to fulfil the high bandwidth requirements of these applications. Among the various on-line strategies proposed to provision such applications, the ones exploiting the connection holding-time knowledge and the flexibility provided by the set-up delay tolerance exhibited a good potential in improving the overall network blocking performance. Considering the fact that the users are willing to wait for provisioning until their set-up delay tolerance expire, it is not of prime importance to establish connection on the earliest available resources. Rather, effective results in terms of network blocking performance can be achieved by provisioning connections on optimal instead of earliest available resources that exist within the set-up delay tolerance. This paper presents novel connection scheduling strategies that efficiently exploit the set-up delay tolerance and holding-time knowledge for dynamic wavelength division multiplexing (WDM) networks. The proposed scheme computes the set of all available provisioning opportunities (at different time instants) within set-up delay tolerance and selects the one that is most efficient in terms of network resource utilization. This scheme is investigated for two different scenarios, that are, for connection requests that cannot be provisioned at the time of their arrival due to resource unavailability and for every request irrespective of whether the required resources for set-up are available or not. Simulation results confirm that the proposed strategies attain significant improvement in network blocking probability compared to earlier presented techniques.