Abstract

The study focuses on packet aggregation mechanisms on the edge router of an optical network. The device works as an interface between the electronic and optical domains : it takes IP packets coming from client layers and converts them into optical packets to be sent into the optical network. An efficient aggregation mechanism supporting QoS (Quality of Service) requirements of IP flows is presented. A timer is implemented to limit the aggregation delay. Analytical models based on Markov chains are presented in order to study the packetisation efficiency (filling ratio) and the mean time of packetisation for each class. Numerical results show the effect of IP packet lengths distribution on aggregation delay and efficiency. Also, we show the importance of the timer in bounding the delay of transmitted packets without much altering the aggregation efficiency.

Abstract

International audience; In this contribution, we consider a novel approach for efficiently supporting IP packets directly into a slotted optical wavelength- division-multiplexing (WDM) layer with several quality of service (QoS) requirements. The approach is based on aggregating IP packets, regardless of their final destinations, at fixed time intervals before the optical conversion phase. A QoS support access mechanism based on the strict priority discipline is evaluated by means of an analytical model. In this case, IP packet aggregation is performed in a loop manner by always beginning the aggregation cycle with the highest priority class. The aggregation cycle ends if the aggregate packet cannot accommodate more IP packets, or if the lowest priority class is reached. In order to overcome the drawbacks of the strict priority discipline, an algorithm depicting a probabilistic priority discipline is presented. The aggregation technique leads to increasing the filling ratio of an optical packet, and consequently, the bandwidth efficiency of an optical network, due to the multicast nature of the aggregation technique. In this context, the support of multicast in metropolitan area networks (MANs), with ring architectures, is presented. Furthermore, a new architecture is proposed in order to support the multicast aggregation technique in wide area networks (WANs)