10403 Abstracts Collection -- Impact of Human Mobility on Communications : Measurement, Analysis, Modeling, and Simulation

From 06.10.2010 to 09.10.2010, the Dagstuhl Seminar 10403 ``Impact of Human Mobility on Communications : Measurement, Analysis, Modeling, and Simulation\u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Support for efficient, scalable delivery of interactive multimedia services

Ph.D.Mostafa H. Amma

Coupons: Wide Scale Information Distribution for Wireless Ad Hoc Networks

Abstract — Integrating ad hoc networks into the Internet requires overcoming a number of difficult technical challenges. In particular, ad hoc networks must not only overcome intermittent connectivity, but they also need a strong incentive mechanism to encourage users to participate in the cooperative relay of data traffic. We believe that inherent in solving these problems is the development of new applications that might, in fact, be more easily deployed in an ad hoc environment than in a traditional fixed network infrastructure. To this end, we develop and evaluate the idea of “coupons ” for wide-scale information distribution in ad hoc networks. “Coupons ” provides a simple incentive to nodes for relaying a piece of information. By using mechanisms on top of basic flooding to efficiently control distribution, it provides an elegant solution for scalable data dissemination with reduced network costs. I

A Long-Term Analysis of Growth and Usage Patterns in the Multicast Backbone (MBone)

The Multicast Backbone (MBone), the Internet's multicast research infrastructure, has existed since the early 1990s. Since its inception, there have been few formal studies investigating the "state of multicast", i.e. the success of multicast deployment. Our work attempts to understand (1) how the MBone is used, (2) how multicast deployment has progressed, and (3) what barriers exist for the continued deployment of multicast. Future research and deployment efforts would benefit significantly with answers to these macro-scale questions. Our work is based on data sets collected over a 4.5 year period. These data sets include join/leave statistics for many of the MBone sessions advertised through the MBone's session directory tool. Using this data, we examine characteristics about the number and frequency of multicast groups and about the users participating in these groups. In addition, we attempt to qualify the accuracy of our results by examining other sources of multicast traffic stat..

Scalable Techniques for Discovering Multicast Tree Topology

The IP multicast infrastructure has transitioned to a topology that now supports hierarchical routing. Multicast network monitoring and management have become key requirements necessary for providing robust multicast operation. Monitoring services help to identify potential problems such as protocol shortcomings, implementation bugs or conguration errors. This type of monitoring often requires knowing the multicast tree topology. In this paper, we present a new approach, called tracetree, to discover tree topology in the source-to-receiver(s) direction using network forwarding state. We start with an overview of the problem. Then, we describe tracetree functionality including its request forwarding and response collection mechanisms. Next, we discuss a number of functional issues related to tracetree. Finally, we evaluate our technique by comparing it to a number of alternative approaches. We believe that our technique provides a scalable way of discovering a multicast tree's topology in realtime while requiring only marginal additional router functionality. 1

Analysis of Routing Characteristics in the Multicast Infrastructure

As the multicast-capable part of the Internet continues to evolve, important questions to ask are whether the protocols are operating correctly, the topology is well connected, and the routes are stable. A critical step in being able to answer these questions is to monitor the traffic and network operation. In this paper, we analyze characteristics of the multicast infrastructure over the last three years using monitoring data collected from several key routers. Specifically, we focus on analyzing two characteristics of the infrastructure: size and stability. The size analysis focuses on counting the number of connected hosts and networks, and analyzing how the size of the infrastructure has changed over past three years. Second, the stability analysis focuses on examining persistence, prevalence, and visibility of routes across the topology. From our analyses, we identify a number of problems with multicast routing and their effect on the connectivity of certain multicast networks. Moreover, we offer insight into the evolution and future of multicast in the Internet. I