Network Coordinate (NC) systems provide a scalable means for Internet distance prediction and are useful for various Internet-based services, such as cloud or web-based services. Decentralized, matrix factorization-based NC (MFNC) systems have received particular attention recently. They can serve large-scale distributed services (as opposed to centralized NC systems) and do not need to satisfy the triangle inequality (as opposed to Euclidean-based NC systems). However, because of their decentralized nature, MFNC systems are vulnerable to various malicious attacks.In this paper, we provide the first study on attacks toward MFNC systems, and propose a trust and reputation-based approach called NCShield to counter such attacks. It is fully decentralized and can easily be customized. Different from previous approaches, NCShield is able to distinguish between legitimate distance variations and malicious distance alterations. Using four representative data sets from the Internet, we show that NCShield can defend against not only the typical disorder, repulsion and isolation attacks, but also more advanced attacks such as frog-boiling attacks. For example, when selecting node pairs with a shorter distance than a predefined threshold in an online game scenario, even if 30% nodes are malicious, NCShield can reduce the false positive rate from 45.5% to 3.7%.
In satellite Multi-Protocol Label Switching (MPLS) networks, the channel fading results in high probability of label transmission error, which causes the erroneous switching of packets. In the context of network-wide performance, only a few poor-quality links will cause severe packet loss and degrade the whole system's performance dramatically. Therefore, the data link layer protection for MPLS labels is necessary in satellite MPLS networks. A new metric, namely, Label Mis-Switching Rate (LMSR) is introduced to measure the capability of label protection. The LMSR for three error control techniques are analyzed, and the analytical results are in excellent agreement with the simulation experiments. According to the results, LMSR could be a valuable metric for satellite MPLS network design and analysis.
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