Improved dynamic weighted cell scheduling algorithm based on earliest deadline first scheme for various traffics of ATM switch

摘要

We propose a new dynamic weighted cell scheduling algorithm using the earliest deadline first (DWEDF) scheme based on cells in an ATM (asynchronous transfer mode) network. Also, we analyze the performances of the proposed scheme and conventional method through simulation. The proposed algorithm can support the QoS (quality of service) of various types of traffic such as VBR (variable bit rate), CBR (constant bit rate), ABR (available bit rate) and UBR (unspecified bit rate) in an ATM multiplexer and switch. Also, the DWEDF algorithm can dynamically schedule cells and support the performance required in the outgoing link according to the QoS parameters. Moreover, the proposed algorithm can support the ABR and UBR services more efficiently due to the 'total bandwidth oriented round cycle property, and suppress incoming cells which violate the QoS parameter by setting a CLP (cell-loss priority) flag in the DWEDF-CLP method or discarding cells in the DWEDF-BLOCK method. Thus, due to reliable ABR and UBR services as well as the congestion avoidance capability, the proposed DWEDF algorithm has good performance over the conventional DWRR (dynamic weighted round robin) scheme. Furthermore, the deadline based cell transmission algorithm in the DWEDF algorithm minimizes the cell delay and requires less temporary buffer size. Thus, the DWEDF algorithm provides reliable support for the QoS of various traffic types in an ATM multiplexer and switch.