A Fair Packet-Level Performance Comparison of OBS and OCS

Introduction

Optical burst-switching (OBS) and optical circuit-switching (OCS) have been proposed as two promising switching paradigms for all-optical networks. They have also stirred interesting debates within the research communities. In an OCS network, data is transmitted over an existing lightpath with sufficient bandwidth. In an OBS network, packets are assembled into bursts, which are injected into the network without setting up a lightpath. Some believe that OBS is suitable for bursty data traffic as it provides statistical multiplexing gains and reduces signaling delay, thereby achieving a higher throughput than OCS, given the same network capacity; Others disagree, pointing to the potentially high burst loss probability in OBS as a main problem. Being able to determine whether OBS or OCS performs better under otherwise identical or similar settings is thus important. However, fair, quantitative performance comparisons between OCS and OBS are difficult as it may be considered to be analogous to comparing an orange and an apple. For example, a common performance metric used for OCS is the blocking probability of lightpath (establishment) requests, which however is not directly comparable to burst (or packet) loss ratio, a common performance metric used for OBS. To the best of our knowledge, there has been no direct quantitative performance comparison between circuit and packet (or burst) switching even for electronic networks involving multiple traffic flows among multiple source and destination pairs. Although there have been a few attempts so far to compare OBS and OCS, the need to establish a common ground on which fair performance comparisons between OCS and OBS can be made clearly exists today more than ever as the research community continues this interesting debate over OBS and OCS.

Simulation

The obs-ocs simulator we developed in this study is based on the discrete event simulation model.
  • The routing, wavelength assignment and self-similar traffic modules of the OCS simulator come from a free software ONSIM developed by Yun Wang.
  • Other modules are developed by Xin Liu.
  • The utilization of this simulator follow the free software rule of GNU.
  • (Use at your own risk and give credit where it is due)
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    The current version is developed under Microsoft VC++ 6.0.

    obs_ocs.tar.gz

    obs_ocs.rar


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