Shared-Path Protection With Delay Tolerance (SDT) in Optical WDM Mesh Networks

Optical wavelength-division-multiplexing (WDM) networks have emerged as an ideal backbone for the dynamic transport of bandwidth-intensive applications. Most emerging applications require end-to-end survivable connections to be set up for specific time durations that have sliding or fixed setup times (such as IPTV, grid computing backup storage). It is critical for the development of future network infrastructure that user-centric, dynamic, and end-to-end management and control mechanisms are devised to bridge the gap between the transport capacity and the needs of new applications at the customer edges. In this paper, we study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and delay tolerances. Delay tolerance is a measure of customer patience, and it is defined as the duration a connection request can be held until it is set up. A connection that cannot be established at the instant of its request could potentially be set up in the remaining duration of its delay tolerance. In this study, different dynamic scheduling algorithms are developed and compared by giving priority to connections according to their arrival rates, delay tolerances, and holding times. Using a mathematical model for impatient requests and simulation experiments, we show that delay tolerance flexibility in the traffic model provides a reduction of up to 50% on blocking probability, without the use of extra backup capacity.