Economic benefits of optical transport layer reconfigurability and tighter coupling with the service layer

With the introduction of fast reconfigurable optical node elements and automatic configurability via signaling, the optical transport layer has become a very dynamic entity. This agility enables capital and operational savings, e.g., due to more efficient utilization of in-place resources, as well as new revenue generating service opportunities, like bandwidth on demand. Additionally, there can be substantial benefits in using the optical layer for restoration. We examine the benefits of optical layer dynamic reconfigurability, especially when there is greater coupling between a packet data service layer (taken here to be IP/MPLS for concreteness) and optical transport layer. We compare failure restoration using only the service layer to various alternatives involving the transport layer, with and without optical layer reconfigurability. We also consider orchestrated restoration between the data and optical transport layers, and propose a joint restoration mechanism. In single-layer restoration paradigms, we find that IP layer restoration is more cost-effective at lower aggregate traffic levels for link failures but, as traffic scales, optical layer restoration is more cost-effective. In multilayer protection paradigms, we find that overlaying joint router protection on transport layer link protection permits strong synergy of protection capacity reuse, thus leading to significant cost savings for operators.