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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)
— We study an idea for efficient integrated protection of an IP over WDM network using the spare capacity of span-protecting p-cycles to provide protection against both optical link failures and router node failures in the IP/MPLS layer. Previously, networks using span-protecting p-cycles were designed from the point of view of a single-layer physical(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)
The neuropathologic findings in a 17-year-old boy with ataxia-telangiectasia are described. In agreement with previous reports, pathologic changes were present in the cerebellum, spinal cord, dorsal root ganglia, and straited muscle. The lesions in the spinal cord and dorsal root ganglia were more severe than previously described. Abnormalities were also(More)