Dynamic routing and resource allocation in time-driven-switched optical networks

The continuous traffic growth keeps challenging operators´ backbone networks, which nowadays are typically implemented through Wavelength Division Multiplexing (WDM) technology. Operators are always looking for new technical solutions to efficiently exploit the bandwidth provided by WDM fiber links, while avoiding undesired increases in network cost and energy consumption. The Time Driven Switching (TDS) technique promises to effectively addresses this issue by enabling the switching of “fractions” of wavelengths thanks to the time-coordination of all network elements. By doing so, connection requests can be efficiently “packed” into WDM links without necessarily converting optical signals into the electronic domain, i.e., traffic grooming can be accomplished directly in the optical domain. In this paper we propose new dynamic routing and scheduling strategies for TDS networks and investigate the performance of a TDS network in terms of blocking probability P_b. Due to the complexity of the joint routing and scheduling, we solve the problem by a two-step approach. Three different routing strategies are evaluated and we observe that P_b is substantially reduced (up to five orders of magnitude lower) when allowing connections to be routed over different wavelengths or different physical paths. We also note that using optical buffers at most reduces P_b 10 times. Moreover we study the variation of the time-frame size switched by TDS nodes, which influences P_b up to two orders of magnitude.