Dynamic scheduling of survivable connections with delay tolerance in wdm networks

In optical wavelength-division multiplexing (WDM) networks, recent technological progress is enabling dynamic optical transport in which leasable circuits (connections) can be set up and released for a specific duration of time, providing large capacity to bandwidth-hungry applications. Set-up times can be flexible or fixed, depending on the type of the application. Since the interruption of a high-speed optical connection could lead to huge loss of data, such connections need to be protected against failures. We study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and particular delay tolerances with shared path protection. The metric of delay tolerance is a measure of customer patience, and it is defined as the time 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. We show that a reduction of up to 50 percent can be achieved on blocking probability by exploiting delay tolerance in networks without using extra backup capacity. In this study we explore different queuing policies for impatient customers. Different dynamic scheduling algorithms are applied and compared by giving priority to connections according to their arrival rates, delay tolerances and holding times alternatively.