Improving service differentiation of immediate and advance reservation in resource-partitioned optical WDM networks

As a result of the rise of Cloud and Grid computing, network operators are requested to improve their resource provisioning systems. In such scenarios, advance reservation (AR) and immediate reservation (IR) are gaining importance. While the former is capable of delivering low connection blocking for delay-tolerant applications, the latter is used by delay-sensitive ones. Even when both IR and AR requests share the same network substrate, service differentiation is needed. Additionally, under network resources partitioning, not only can the overall network capacity be under-utilized, but service differentiation can also be degraded. In this paper, we assess hybrid IR/AR sharing and partitioning mechanisms in optical wavelength-division multiplexing (WDM) networks, and propose efficient schemes for providing relative quality of service (QoS) differentiation among traffic classes. In order to overcome the poor resource utilization of strict partitioning, we develop and evaluate a preemption-based flexible partitioning framework aiming to provide relative QoS in hybrid IR/AR environments still supporting resource partitioning. Two preemption policies are proposed: switch first then preempt (SFTP) and preempt first then switch (PFTS). Through extensive simulations, we show that the proposed flexible partitioning framework can improve resource utilization, lower the overall blocking, and achieve well-differentiated relative QoS compared to strict partitioning.