Network studies in IP/optical layer restoration

Even though transport of an equivalent amount of bandwidth at the IP layer is much more expensive than at the optical layer, it is not universally true that restoration of span failures is less expensive when provided at the optical layer. Some critical factors that determine this are single or dual router office architectures and pre and post-failure IP-layer link utilization levels. Furthermore, it was shown that integrated IP/OL restoration can give substantial benefits over restoration by either layer alone.