Distributed Network Scheduling for Time-domain Wavelength Interleaved Networks

Time-domain Wavelength Interleaved Network (TWIN) is a newly proposed thin-layer network that provides transport services for synchronous and asynchronous traffic. Each source node has a tunable laser to transmit bursts to various destinations. The interior nodes route each burst independently based on the wavelength of the burst. Each destination node has a burst-mode receiver capable of decoding each burst intended to it. {em Network} scheduling is a critical component that arbitrates burst transmissions from various sources to destinations so that conflicts are avoided and resource efficiency is maximized. Network scheduling in TWIN has to deal with geographically distributed nodes and the propagation delays that exist between various nodes. In this paper, we propose a distributed protocol that performs scheduling of bursts in a network with non-zero propagation delays. The protocol uses a combination of randomization and bumping techniques to allow for reassignments of time slots. We investigate the performance of the proposed distributed protocol under two broad types of traffic: synchronous traffic and asynchronous traffic. With synchronous traffic, the results indicate that the distributed protocol with source bumping can achieve the efficiency comparable to that realized by a centralized scheduler. With asynchronous traffic, the distributed protocol is able to effectively track the dynamic changes in traffic demands. The responsiveness, however, is dependent upon the propagation delays. The results also reveal that source bumping can increase the achievable throughput with asynchronous traffic.