CA‐STAR: a centrally‐arbitrated broadcast‐and‐select star architecture for lightwave networks

Abstract

Parallel use of multiple channels in WDM star networks requires that either each station is equipped with one receiver per channel or we have to deal with destination conflicts whenever a station is reached by more packets than it is able to receive. Earlier proposed networks resolved destination conflicts either after they occur (applying the detect‐and‐retransmit‐if‐lost principle) or before packets are transmitted (applying the request‐schedule‐then‐transmit principle). This paper introduces networks in which such conflicts are resolved whilst packets are en route to their destinations, using a central arbiter station (CA) located at the star coupler. CA detects destination conflicts, buffers packets which would otherwise be lost, and forwards them to their destinations as soon as their destinations are free to receive them. Buffer operations at CA are streamlined, allowing either electronic implementation or a simple optical delay‐line implementation. Their performance is evaluated by studying their delay and throughput characteristics, protocol computational complexity, E/O conversion overhead, and hardware demands.