International audienceTraceroute is widely used, from the diagnosis of network problems to the assemblage of internet maps. However, there are a few serious problems with this tool, in particu-lar due to the presence of load balancing routers in the net-work. This paper describes a number of anomalies that arise in nearly all traceroute-based measurements. We categorize them as "loops", "cycles", and "diamonds". We provide a new publicly-available traceroute, called Paris traceroute, which controls packet header contents to obtain a more pre-cise picture of the actual routes that packets follow. This new tool allows us to find conclusive explanations for some of the anomalies, and to suggest possible causes for others

Because a delay tolerant network (DTN) can often be partitioned, the problem of routing is very challenging. However, routing benefits considerably if one can take advantage of knowledge concerning node mobility. This paper addresses this problem with a generic algorithm based on the use of a high-dimensional Euclidean space, that we call MobySpace, constructed upon nodes' mobility patterns. We provide here an analysis and the large scale evaluation of this routing scheme in the context of ambient networking by replaying real mobility traces. The specific MobySpace evaluated is based on the frequency of visit of nodes for each possible location. We show that the MobySpace can achieve good performance compared to that of the other algorithms we implemented, especially when we perform routing on the nodes that have a high connection time. We determine that the degree of homogeneity of mobility patterns of nodes has a high impact on routing. And finally, we study the ability of nodes to learn their own mobility patterns.Comment: IEEE INFOCOM 2006 preprin

Routing in Delay Tolerant Networks (DTNs) benefits considerably if one can take advantage of knowledge concerning node mobility. The main contribution of this paper is the definition of a generic routing scheme for DTNs using a high-dimensional Euclidean space constructed upon nodes' mobility patterns. For example, nodes are represented as points having as coordinates their probability of being found in each possible location. We present simulation results indicating that such a scheme can be beneficial in a scenario inspired by studies done on real mobility traces. This work should open the way to further use of the virtual space formalism in DTN routing.

A good understanding of contact patterns in delay tolerant networks (DTNs) is elemental to the design of effective routing or content distribution schemes. Prior work has typically focused on inter-contact time patterns in the aggregate. In this paper, we argue that pairwise inter-contact patterns are a more refined and efficient tool for characterizing DTNs. First, we provide a detailed statistical analysis of pairwise contact and inter-contact times in three reference DTN data sets. We characterize heterogeneities in contact times and inter-contact times, and find that the empirical distributions of inter-contact times tend to be well fitted by log-normal curves, with exponential curves also fitting a significant portion of the distributions. Second, we investigate analytically the relationship between pairwise and aggregate inter-contact times. In particular, we consider both the exponential and log-normal cases and show analytically how the aggregation of pairwise inter-contacts may lead to aggregate inter-contacts with power laws of various degrees.