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We consider survivable virtual network mapping in a multi-domain optical network with the objective of minimizing total network link cost for a given virtual traffic demand that is embedded over the multi-domain optical network. The survivability constraint guarantees the connectivity of virtual nodes after any single optical link failure. We propose a hierarchical software-defined networking (H-SDN)-based control plane to exchange information between domains, and we propose heuristic approaches for mapping virtual links onto multi-domain optical links using partition and contraction mechanisms (PCM) on the virtual topology. We show that the proposed PCM technique can reduce time complexity compared to traditional cut set graph theory approaches. Numerical results show that our heuristic approach is effective in reducing total network cost and increasing the successful mapping rate.

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As distributed denial-of-service (DDoS) attacks have caused serious economic and social problems, there have been numerous researches to defend against them. The current DDoS defense system relies on a dedicated security device, which is located in front of the server it is required to protect. To detect DDoS attacks, this security device compares incoming traffic to known attack patterns. Since such a defense mechanism cannot prevent an influx of attack traffic into the network, and every packet must be compared against the known attack patterns, the mechanism often degrades the service. In this paper, we propose the Serviceoriented DDoS Detection Mechanism using a Pseudo State (SDM-P), which runs on network devices to defend against DDoS attacks without sacrificing performance in terms of data Multimed Tools Appl forwarding. The SDM-P mechanism is suitable for both low-and high-rate attacks. In addition, we verified the performance of the SDM-P mechanism by evaluating its performance using a DDoS attack similar to the one that occurred in Korea and the USA on July 7th, 2009.

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