Abstract-Recently, there has been a surging interest on anonymizer technologies as a result of increasing privacy concerns and raising censorship barriers around the world. Tor network has emerged as the most popular option in avail thanks to its large volunteer base. However, popularity of Tor network is under threat of growing user frustration over low throughput and long latencies. Coincidentally multi-path routing proposals have become popular in tackling the similar performance issues in various contexts from data center networks to inter-domain routing. In this work, we apply multi-path techniques so as to overcome limitations in Tor's path construction and rigid congestion avoidance mechanisms which are major factors behind the unsatisfactory user experience. It turns out that multipath mechanisms nicely complement underlying onion-routing mechanisms of Tor via exploiting diversity in Tor network. Our preliminary evaluation on live Tor network revealed the significant potential of performance improvements achieved by multi-path techniques especially in increasing throughput which can offer up to 4 times speed up in data transmission durations. Also, multi-path mechanisms may increase reliability of the overall system against congestion or service-interruption based attacks in return of acceptable anonymity trade-offs. Besides these very promising features, application of multi-path techniques on anonymized routing introduces many open research questions calling for further research on data splitting, path construction, latency estimation techniques whose findings can benefit many research areas.

Optimization of flows to maximize Wireless Sensor Network (WSN) lifetime is a problem already investigated in various aspects. However, most studies ignored the effects of finite bandwidth. As source data rate of sensor nodes increases, flow patterns that balance energy dissipation optimally might need more bandwidth than available. As a result, ignoring bandwidth limitations may lead to infeasible solutions. In this study, we make a comprehensive evaluation of the impacts of finite bandwidth by building a linear programming framework. The objective is the minimization of the energy expenditure in the maximum energy-dissipating node to achieve the maximum lifetime under bandwidth constraints. Our analysis reveals that energy consumption values may stay constant until a threshold data rate is reached. But, after the threshold the energy values increase because suboptimal paths are used due to bandwidth constraints. The bandwidth for optimal energy dissipation is limited approximately by twice the minimum bandwidth requirement.

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Abstract-Internet topology modeling involves capturing crucial characteristics of the Internet in producing synthetic network graphs. Selection of vital metrics is limited by our understanding of the Internet topology, which relies on the state of the art measurement studies. Recent measurement studies indicate that underlying subnetworks, multi-access links providing one-hop connectivity to multiple nodes, are an important factor shaping the topology of the Internet. Current network models utilize point-to-point edges that can connect exactly two vertices of the topology. Decomposition of the underlying multi-access links into pairwise point-to-point edges results in cliques and is an oversimplification of the analyzed networks. Accurate modeling of multi-access links require special type of edges, i.e. hyper-edges, that can connect multiple vertices in a hyper-graph. Hyper-graphs are best illustrated as bipartite graphs where hyper-edges connect two types of vertices, i.e., router interfaces and subnets. In this paper, we introduce a bipartite model of the Internet topology and discuss representative synthetic network generation.

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