BR-WRR scheduling algorithm in PFTS

Abstract

The novel concept of Physical Frame Time-slot Switching (PFTS) over DWDM, proposed by Sichuan Network and Communication technology key laboratory (SC-Netcom Lab), 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 a Borrow & Return Weighted Round Robin (BR-WRR) algorithm of output scheduling and dispatching 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. Furthermore, multiple queues with different priorities plus burst queue with the highest priority are devised for each output lambda. A Borrow-and-Retum mechanism is introduced to improve the orthodox WRR in PFTS, which cannot satisfy continuous transmitting privileged data of a burst to maintain its integrity. Comparison of the results between simulation of BR-WRR and that of WRR is provided in this paper and shows that BR-WRR has better performance with regard to fairness and important QoS parameters such as transit delay, jitters, and non-disordering. © Springer-Verlag Berlin Heidelberg 2004.