Extended DWRR scheduling algorithm in PFTS

The novel concept of physical frame time-slot switching (PFTS) over DWDM (Huaxin Zeng, et al., 2003) has been around for some time. It differs from existing switching techniques over DWDM by its superior QoS mechanisms embedded in and its capability to simplify Internet into a single physical-layer user-data transfer platform architecture (SUPA). This paper proposed the extended deficit weighted round robin (EDWRR) algorithm of output scheduling in a multiple-priority queue environment in PFTS nodes. In such nodes, there are multi-ports in a DWDM-based PFTS node and each port contains multi-lambdas. EDWRR guarantees the delay property of real-time traffic and also efficiently transmits non-real-time traffic. The proposed scheduling algorithm is an improvement and extension of deficit weighted round robin (DWRR) algorithm and guarantees the delay property of real-time traffic by adding a frame transmission procedure based on delay priority. Simulations show that EDWRR has better performance than DWRR in QoS provision of real-time traffic.