ISSN : 1796-2056
Volume : 2    Issue : 4    Date : August 2007

Contention Resolution by Retransmission in Single-hop OPS Metro Networks
Akbar Ghaffar Pour Rahbar and Oliver W. W. Yang
Page(s): 20-27
Full Text:
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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.

Index Terms
slotted OPS, retransmission in the optical domain, additional wavelengths, contention avoidance.