Defragmentation algorithm for joint dynamic and static routing problems in elastic optical networks with unicast and anycast traffic

Elastic Optical Network (EON) is a new optical technology proposed to overcome limitations of the currently used Wavelength Division Multiplexing (WDM) technology. The key advantages of EONs are efficient use of spectrum resources compared to classical fixed-grid in WDM networks and support of flexible modulation format conversion. Noteworthy trends observed in the last few years in communication networks are cloud computing and content-oriented services, provided by geographically dispersed data centers. Anycast transmission - defined as one-to-one-of-many - is attracting a lot of interest, since the network providers require cost-effective and scalable data delivery techniques in inter-data center networks. In this paper, we propose a new defragmentation algorithm for EONs. The key goal of the algorithm is to improve the network performance under dynamic traffic scenarios in terms of blocking probability and usage of regenerators. An important novelty of our approach is that we apply the defragmentation algorithm for both dynamic as well as for static traffic allocated in the network before the arrival of dynamic requests. Extensive numerical experiments run on real topologies with realistic traffic patterns following Cisco predictions show, that our defragmentation algorithm can significantly improve the network performance in terms of blocking probability and usage of regenerators.