Contention Resolution by Retransmission in Single-hop OPS Metro Networks

Abstract

We consider a single-hop slotted all-Optical Packet-Switched (OPS) metro network where contention is the major problem. Since contention resolution hardware such as optical buffers and wavelength converters are expensive, we do not use any of these contention resolution hardware inside a core switch. Instead, we consider the retransmission in the optical domain which appears to be the cheapest solution. We study the prioritized retransmission schemes where dropped traffic has a priority when retransmitted from edge switches. Our study shows that the number of retransmissions can be significantly reduced. We present the analysis in a singlefiber network where additional wavelength channels are used to carry the same traffic. In addition to verifying our analysis, our simulation results demonstrate the capability and the advantage of PR over the traditional RR (Random Retransmission) as well as the advantage of using multiple wavelengths over using multiple fibers.