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—We describe a novel restoration strategy called virtual protection cycles (cycles , patents pending) for extremely fast restoration in IP networks. Originally conceived for use in WDM and Sonet transport networks, we outline the adaption of the-cycle concept to an IP environment. In an IP router-based network ,-cycles are implemented with virtual circuits(More)
—Recent work on restorable networks has shown experimentally that one can support 100% restoration with an optimized set of closed cycles of spare capacity while requiring little or no increase in spare capacity relative to a span-restorable mesh network. This is important and unexpected because it implies that future restoration schemes could be as(More)
—The most common aim in designing a survivable network is to achieve restorability against all single span failures, with a minimal investment in spare capacity. This leaves dual-failure situations as the main factor to consider in quantifying how the availability of services benefit from the investment in restorability. We approach the question in part(More)
—Distributed path restoration based on optical cross-connects can provide highly capacity-efficient real-time restoration for WDM-based optical networking. However, to obtain an assured restoration level with the theoretically very low amounts of spare capacity that path restoration allows, one must solve, or closely approximate a solution to, the integer(More)
We consider extensions of the most common mesh-restorable network capacity design formulation that enhance the dual-failure restorability of the designs. A significant finding is that while design for complete dual-failure restorability can require up to triple the spare capacity, dual failure restorability can be provided for a fairly large set of priority(More)
—This work introduces a significant extension to the method of-cycles for network protection. The main advance is the generalization of the-cycle concept to protect path segments of contiguous working flow, not only spans that lie on the cycle or directly straddle the-cycle. This effectively extends the-cycle technique to include path protection or(More)