Scheduling Variable-Size Packets in the DAVID Metropolitan Area Network

A. BIANCO, J. M. FINOCHIETTO, G. GALANTE, F. NERI, V. SARRA

Paris, Francia

Conferencia; IEEE International Conference on Communications (ICC 2004); 2004

DAVID is a research project sponsored by the EuropeanUnion aimed at the design of an optical packet-switchednetwork for the transport of IP traffic. The DAVID network hasa two-level hierarchical structure, with a backbone of opticalpacket routers inter-connected in a mesh, and metropolitanareas served by sets of optical rings interconnected by passivememoryless devices called Hubs.The paper focuses on the metropolitan area network andits components: the nodes and the Hub. Access is regulatedby a dynamic time-division multiple-access scheme allocatingslots in sets of wavelengths that provide multi-channel pipesamong ring pairs. This paper proposes a new resource allocationscheme capable of transporting variable-size packets withoutsegmentation into fixed-size data units. Resource sharing amongnodes is granted by two scheduling algorithms running ondifferent time scales: the first one is centralized at the Hub andprovides coarse connectivity among ring pairs; the second oneruns at nodes and provides finer node-to-node connectivity.The Hub scheduling algorithm is derived from well known algorithmsin the literature; a novel heuristic scheduling algorithmrunning at nodes is proposed for datagram (not-guaranteed)traffic and its performance is studied by simulation.