Ethernet passive optical networks (EPONs) are being designed to deliver multiple services and applications, such as voice communications, standard and high-definition video (STV and HDTV), video conferencing (interactive video), real-time and near-real-time transactions, and data traffic. To support these applications with their diverse requirements, EPONs need to have class-of-service (CoS) mechanisms built in. Here we investigate how the Multipoint Control Protocol (MPCP)—an EPON transmission arbitration mechanism—can be combined with a strict (exhaustive) priority scheduling that is a default scheduling algorithm specified in the Institute of Electrical and Electronics Engineers (IEEE) 802.1D standard. Specifically, packet delays for different classes of traffic are analyzed. We find that the queuing delay for lower-priority classes increases when the network load decreases (a phenomenon we call light-load penalty). We also suggest and analyze two different optimization schemes that eliminate the light-load penalty.
© 2002 Optical Society of AmericaPDF Article