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A fault-tolerant scheme, called dual homing, is generally used in IP-based access networks to increase the availability of the networks. In a dual-homing architecture, a host is connected to two different access routers; therefore, it is unlikely that the host will be denied access to the network as the result of an access line break, a defective power supply in the access router, or congestion of the access router. This dual-homing architecture in the access network imposes the overhead to provide protection in the core network. Scaling the next-generation IP-over-wavelength-division-multiplexing (WDM) Internet, and being able to support a growing number of such dual-homing connections, as well as protection, demands a scalable mechanism to contain this overhead for protection in the WDM networks. This paper studies the coordinated protection design to reduce the protection cost in the WDM core network, given a dual-homing infrastructure in the access network. The protection problem is considered for both static and dynamic traffic. Several solutions are proposed, and the performances of the solutions are compared. We also prove that one of the proposed algorithms gives a solution that, in the worst case, is at most 4/3 times the cost of the optimal solution.
Date of Publication: Oct. 2005