Economic Benefits of Optical Transport Layer Reconfigurability and Tighter Coupling with the Service Layer

We examine the benefits to network operators 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 an 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 give an example of a proposed joint restoration mechanism. In single-layer restoration paradigms, we find that IP layer restoration is more cost-effective at lower aggregate traffic lavels for link failures but, as traffic scales, optical layer restoration is more cost-effective. In multi-layer protection paradigms, we find that overlaying joint router protection on transport layer link protection permits strong synergy of protection capacity reuse, this leading to significant cost savings for operators.