Fluid limit of an asynchronous optical packet switch with shared per link full range wavelength conversion

  • Authors:
  • Benny Van Houdt;Luca Bortolussi

  • Affiliations:
  • University of Antwerp, Antwerp, Belgium;University of Trieste, Trieste, Italy

  • Venue:
  • Proceedings of the 12th ACM SIGMETRICS/PERFORMANCE joint international conference on Measurement and Modeling of Computer Systems
  • Year:
  • 2012

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Abstract

We consider an asynchronous all optical packet switch (OPS) where each link consists of N wavelength channels and a pool of C ≤ N full range tunable wavelength converters. Under the assumption of Poisson arrivals with rate λ (per wavelength channel) and exponential packet lengths, we determine a simple closed-form expression for the limit of the loss probabilities Ploss(N) as N tends to infinity (while the load and conversion ratio σ=C/N remains fixed). More specifically, for σ ≤ λ2 the loss probability tends to (λ2-σ)/λ(1+λ), while for σ λ2 the loss tends to zero. We also prove an insensitivity result when the exponential packet lengths are replaced by certain classes of phase-type distributions. A key feature of the dynamical system (i.e., set of ODEs) that describes the limit behavior of this OPS switch, is that its right-hand side is discontinuous. To prove the convergence, we therefore had to generalize some existing result to the setting of piece-wise smooth dynamical systems.