This paper describes work performed for the Defense Advanced Research Projects Agency CORONET-funded Protocols and Architectures for Resilient Agile Global Optical Networks project to build an integrated IP/optical layer (OL) restoration architecture that combines transponder-shared mesh restoration at the OL with innovative methods of using router line cards and OL reconfigurability to restore from a layer 3 outage. This is a significant advancement over current restoration strategies, which typically add significant additional layer 3 capacity (i.e., additional IP links) to allow all failures to be restored at layer 3 alone. The network and restoration architectures in the integrated restoration method are described, as are design methodologies for each layer. A realistic cost model is applied to demonstrate that the proposed integrated IP/OL restoration strategy may have significant cost advantages for a core IP network when compared to the commonly used restoration strategies today.
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