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As the most popular anonymous communication system, Tor provides anonymous protection for users by sending their messages through a series of relays. Due to the use of the bandwidth-weighted path selection algorithm, many more users choose routers with high bandwidth as relays. This will cause the utilization of high bandwidth routers to be much higher than that of low bandwidth routers, which will bring congestion risk. The Quality of Service (QoS) is difficult to guarantee for users who need delay-sensitive services such as web browsing and instant messaging. To reduce the average load of routers and improve the network throughput, we propose a circuit construction method with multiple parallel middle relays and conduct a dynamic load allocation method. The experiment demonstrates that our proposed method can provide better load balancing. Compared with other multipath anonymous communication networks, our proposed method can provide better anonymity. [ABSTRACT FROM AUTHOR]

The construction of data center network by applying SDN technology has become a hot research topic. The SDN architecture has innovatively separated the control plane from the data plane which makes the network more software-oriented and agile. Moreover, it provides virtual multi-tenancy, effective scheduling resources and centralized control strategies to meet the demand for cloud computing data center. However, the explosion of network information is facing severe challenges for SDN controller. The flow storage and lookup mechanisms based on TCAM device have led to the restriction of scalability, high cost and energy consumption. In view of this, a source-controlled data center network (SCDCN) model is proposed herein. The SCDCN model applies a new type of source routing address named the vector address (VA) as the packet-switching label. The VA completely defines the communication path and the data forwarding process can be finished solely relying on VA. There are four advantages in the SCDCN architecture. 1) The model adopts hierarchical multi-controllers and abstracts large-scale data center network into some small network domains that has solved the restriction for the processing ability of single controller and reduced the computational complexity. 2) Vector switches (VS) developed in the core network no longer apply TCAM for table storage and lookup that has significantly cut down the cost and complexity for switches. Meanwhile, the problem of scalability can be solved effectively. 3) The SCDCN model simplifies the establishment process for new flows and there is no need to download flow tables to VS. The amount of control signaling consumed when establishing new flows can be significantly decreased. 4) We design the VS on the NetFPGA platform. The statistical results show that the hardware resource consumption in a VS is about 27% of that in an OFS. [ABSTRACT FROM AUTHOR]

ABSTRACT Intrusion detection has become an indispensable technique to ensure the security and reliability of information systems. Support vector machine (SVM) and its many improved algorithms have been successfully applied to intrusion detection systems in recent years. However, the training process of SVM ignores an important prior knowledge, the within-class structure in the training set. In this paper, we propose an improved classification algorithm, which combines minimum within-class scatter in Fisher discriminant analysis with traditional SVM. The central idea is to find an optimal separating hyperplane such that the margin is maximized, whereas the within-class scatter is kept as small as possible. This new algorithm is called SVM with minimum within-class scatter (WCS-SVM). A set of experiments is conducted on ten benchmarking datasets and KDDCUP'99 experimental data of MIT Lincoln Laboratory to test the generalization performance of the WCS-SVM algorithm. Experimental results show that the WCS-SVM algorithm has better discriminatory power than traditional SVM and kernel Fisher discriminant analysis and it has higher true detection rate and lower false positive rate for intrusion detection systems. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]