Supporting quality of service by using delta dynamic bandwidth allocations in Ethernet passive optical networks

Abstract

In Ethernet passive optical networks (EPONs), dynamic bandwidth allocation (DBA) has to provide efficient and statistical multiplexing between the optical network units for better upstream use. Here a new burst-polling-based delta (DBA) scheme is proposed for quality of service (QoS) using class of service (CoS) in EPONs. The proposed scheme consists of two parts: one is inter-ONU scheduling, which is a delta DBA based on burst polling, and the other is OLT-based intra-ONU scheduling, a differentiated priority queuing method at egress, in which three kinds of traffic classes have been considered, such as expedited forwarding (EF), assured forwarding (AF), and best effort (BE). With the proposed scheme, it has been shown that the network resources are optimally utilized and adaptively allocated to the three traffic classes by guaranteeing the requested QoS. For the verification and validation of the algorithm, experimental simulation results using OPNET have been presented, and these show that the proposed scheme under varying offered loads gives an improvement compared with the other DBA schemes in the content of (criteria) packet delay, queue length, and channel utilization--especially when the offered load is beyond the system's capacity. Specifically, packet-delay variations (PDV) for different classes of traffic are demonstrated.