Photonic Network Defragmentation Technology Improving Resource Utilization during Operation

Recently, various new information services have emerged as a means for sustaining the significant growth of modern applications spearheaded by cloud and smartphones. These new services rely heavily on the underlying network and data center infrastructures. Thus, core networks are demanded to further expand the capacity to support the rapid increase in data traffic. Meanwhile, it is becoming increasingly important for core networks to be more flexible in order to accommodate feature-rich services such as bandwidth-on-demand. Additionally, for the realization of a sustainable human society and eco-friendly IT services, products capable of low energy consumption are strongly desired. In the near future, it is expected that conventional optical networks which operate on a rigid fixed channel basis will be replaced by flexible optical networks in which signals can be freely allocated on arbitrary frequency slots of the optical spectrum. This flexibility enables a more dynamic and efficient utilization of resources, which in turn leads to lowered energy consumption, heightened usable capacity, and superior agility, making it capable of providing adaptive networking services based on the dynamism of user requests. In flexible optical networks, due to the frequent setup and tear down of optical signals that occupy different spectrum slots, the utilization of such slots has the potential to become heavily fragmented. This so-called spectrum fragmentation phenomenon dramatically degrades resource utilization and reduces usable network capacity. Therefore, spectrum defragmentation technology that Fujitsu Laboratories has developed is needed to restore efficient resource utilization by reallocating the fragmented slots to more continuous ones. In this paper, we discuss a photonic network defragmentation technology that can improve resource utilization during network operation by continuous and in-sync reconfiguration of flexible optical nodes (transceivers and optical switches, etc.). We show the effectiveness of this technology through network simulations, as well as experimental results of hitless defragmentation.