Contention-Free λ-Planes in Optically Burst-Switched WDM Networks

Kouji HIRATA  Takahiro MATSUDA  Hiroshi NAGAMOCHI  Tetsuya TAKINE  

IEICE TRANSACTIONS on Communications   Vol.E90-B   No.9   pp.2524-2531
Publication Date: 2007/09/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.9.2524
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Internet
optical burst switching,  WDM,  wavelength assignment,  burst scheduling,  

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This paper proposes a contention-free burst scheduling scheme for optically burst-switched WDM networks. We construct contention-free wavelength planes (λ-planes) by assigning dedicated wavelengths to each ingress node. Bursts are transmitted to their egress nodes on λ-planes, along routes forming a spanning tree. As a result, contention at intermediate core nodes is completely eliminated, and contention at ingress nodes is resolved by means of electric buffers. This paper develops a spanning tree construction algorithm, aiming at balancing input loads among output ports at each ingress node. Furthermore, a wavelength assignment algorithm is proposed, which is based on the amount of traffic lost at ingress nodes. We show that the proposed scheme can decrease the burst loss probability drastically, even if traffic intensities at ingress nodes are different.