Contention Resolution by Retransmission in Single-hop OPS Metro Networks

Abstract

<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 8.5pt;">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.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 8.5pt;"></span></p

Improving throughput of long-hop TCP connections in IP over OPS networks

“…However, the number of retransmissions is not limited in RR, and the multiple retransmissions may lead to a further higher-level (say, TCP layer) retransmission, which may in turn reduce the network throughput, and (2) the Prioritized Retransmission (PR) scheme [9,10,18] in which a few bits, as a priority field, are used to keep the priority of each optical packet. This field is the criterion by which an OPS switch decides to prioritize optical packets in order to find the eligible ones for switching.…”