A Distributed Route Computation Method to Promote Bandwidth Sharing between Backup Lightpaths

Hideaki TANAKA

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.10    pp.3930-3940
Publication Date: 2005/10/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.10.3930
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Next Generation Photonic Network Technologies)
survivable optical network,  shared mesh restoration,  distributed route computation,  modified link weight,  Markov decision theory,  

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The optical network is a promising approach for realizing a scalable backbone network. In backbone networks, survivability is very important because great volumes of traffic incur damage from faulty equipment. To address this issue, various recovery schemes have been proposed for optical backbone networks. Among those schemes, shared mesh restoration utilizes link bandwidth efficiently because the backup lightpaths share link bandwidth if they protect against different failures and are never utilized simultaneously. However, a route computation method for the backup lightpaths that promotes such bandwidth sharing is necessary to achieve efficient bandwidth utilization. This paper proposes a distributed route computation method for the backup lightpaths in shared mesh restoration. In this method, the link weight is estimated to be smaller if a backup lightpath newly established can share the link bandwidth with the backup lightpaths already accommodated in that link. The link weight can be calculated using the Markov Decision Theory. The bandwidth sharing between the backup lightpaths can be promoted by selecting the shortest route based on such modified link weights. The proposed method effectively realizes efficient utilization of the link bandwidth and achieves low loss rate of reliable lightpath establishment requests under the same traffic load. The proposed method restricts the amount of link state information advertised by the routing protocol and achieves a sufficiently small amount of route calculation.