Restoring Optical Cloud Services using Relocation

Optical cloud is a very popular concept by which storage and computing resources (i.e., IT resources) are distributed over different datacenter (DC) locations interconnected via high-speed optical wavelength division multiplexing (WDM) links. In this paradigm cloud services are provisioned in an anycast fashion, where only the source node needs to be specified in the routing and resource assignment phase, while any DC (with enough IT resources) can be used to accommodate a cloud service. Anycast provisioning has a number of advantages already recognized by optical cloud providers [1][2]. This kind of provisioning paradigm allows, for example, for the live relocation of the already provisioned cloud services, referred to as the service relocation concept. It means that if the DC location is not essential for the execution of a certain cloud service, multiple relocations of the job to other DC locations are possible. This allows for a more efficient management of both the cloud and the transport network resources. Service relocation has also the potential to bring an extra degree of flexibility to survivability strategies. By providing the option for relocating a cloud service it is possible to use a backup path terminating at a DC that is different from the one used by the primary path. This benefit has been assessed in the literature showing the ability to improve resources efficiency by using service relocation in conjunction with path protection strategie