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Challenged Networking

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Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 450 Challenged Networking An Experimental Study of new Protocols and Architectures ERIK NORDSTRÖM ACTA
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Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 450 Challenged Networking An Experimental Study of new Protocols and Architectures ERIK NORDSTRÖM ACTA UNIVERSITATIS UPSALIENSIS UPPSALA 2008 ISSN ISBN urn:nbn:se:uu:diva-9002 If I have seen further it is by standing on the shoulders of giants. Sir Isaac Newton Preface Five years make a long time. It is certainly ample time to ponder on the reasons for pursuing a Ph.D., and for engaging in research. Many such reasons that are now obvious to me were not clear at the beginning of my journey they have emerged gradually during the course of it. One of the reasons for engaging in research, which I believe in, is to contribute to a common pool of knowledge. There is a famous saying that we are standing on the shoulders of giants 1. Furthering our knowledge is a collaborative process that consists of incremental steps. This process is how we in the long run affect the evolution of our society and, by extension, our world. Some thinkers of course produce more disruptive research than others. However, whether research is disruptive or not, often only time can tell. In either case, if research is not accessible, interesting, understandable, and educational for people, it might as well never have existed to begin with. Informing others of your research, especially those that are not professionals, I have learnt can be highly motivational and constructive for your work but it is also a major challenge. Fortunately, this thesis is all about challenges. Thus, a goal has been to make this thesis accessible (at least in parts) also to people not necessarily familiar with computer networking. Whether I have succeeded or not is up to the reader to decide. This goal, however, does not imply that this thesis is free from technical jargon and intricate details. So beware! Often friends and family have asked me about my research. Equally often I have tried to avoid giving an answer. One reason for this unwillingness to explain is simply that I prefer not to talk about work when I am not working. Another reason is that I quickly learned that it was hard to explain in limited time (e.g., imagine doing it at a party before a person looses interest), or that it was obvious that the person was just being polite by asking and in fact could not care less. The people that actually do want to know: here is your chance! Keep on reading. During five years many things can change not only in terms of research, but also in life in general. This life I quickly learnt can suffer if you are sucked too deeply into what you are doing. I therefore decided early on that I would honor the life outside of work, and at the same time to embrace some of the perks of being a doctoral candidate in my area. These perks include free plan- 1 This metaphor is attributed Bernard of Chartres, but was made famous by Sir Isaac Newton. v ning of time (which can both be a blessing and a curse), working in an environment where you meet and interact with people of many different backgrounds, and last but not least the opportunity to travel to many interesting countries and places. These perks have not only been good for me as a researcher; they have also made me a better and more enlightened person. To have had the fortune to do all these things, such as enjoying perks and engaging in interesting research, has been a privilege. This privilege would not have been possible without the support of many people. My gratitude goes to all of these people, which I will here try to list without forgetting someone. My gratitude first and foremost goes to my closest family: my parents Jan- Eric and Eva, and my sister Jenny. They have not always understood what I have been doing in my research, but have always supported me in my decision to pursue it. When life has been difficult, in work or otherwise, they have always been there to pick me up. My closest family, and my other relatives, have my everlasting love and gratitude. My friends outside of work have been my retreat and safe haven from everything work related. They are too numerous to list here, and if I tried I would be afraid to forget somebody. You know who you are! I am grateful for having such diverse friends that do everything but researching challenged networking. They have given me broader perspectives, which undoubtedly have made me better in many ways, including in my research. My colleagues in the Communications Research (CoRe) group have been instrumental to my success as a Ph.D. candidate. These are: Richard Gold, my partner-in-crime and friend. Endless have our discussions been sometimes heated, often challenging, always insightful. I am grateful for these insights, for the patience shown when listening to my complaints at times of low motivation, and for reminding me not to take work too seriously when I shouldn t. Olof Rensfelt, whose research seems to be only one hobby of many that he excels in. Apart from his research, I especially appreciate his beer making skills and excellent cooking, which can always be enjoyed through a level of hospitality challenged only by his wife Agnes. Henrik Lundgren, who during my first year was my close collaborator and co-author on many of my papers. He is a friend that was a familiar face in Paris during my visit there. Christian Rohner who has been a loyal work companion, and has always been able to put up with my sometimes strong opinions on how to do things. Christian Tschudin, who after he left the group has acted as my external supervisor. His refreshing ideas and unchallenged technical skills have been an inspiration. David Lundberg and Mattis Fjällström, who I have had the privilege working with early on in my studies. The rest of the colleagues in the CoRe group have always inspired and supported; Lars-Åke Larzon, Arnold Pears, Oskar Wibling, Ioana Rodhe, Fredrik Bjurefors, Thabotharan Kathiravelu, and Laura Feeney. Numerous are also the students, research assistants, alumni people, and visitors that I have been fortunate enough to have met and interacted with. All of these people have my gratitude. vi I am also thankful to my colleagues at the Thomson research lab in Paris, where I did an internship ( ). Christophe Diot, who was kind enough to host me, and whose open mind (often spoken in a refreshingly direct manner) gave me fresh inspiration during the final years of my Ph.D. studies. My gratitude also goes to all of the others in the lab that made my stay in Paris a rememberable one: Amogh, Vivek, Andy, Augustin x 2, Laurent, Vincent, Letizia, Haakon, Ming, Abderrahmen, Theodoros, Anna-Kaisa, Fernando, Marianna, and others. Last, but not least, my supervisor and mentor Per Gunningberg. He has always believed in me, supported me, and given me the freedom that every researcher wants but perhaps not always takes advantage of to the fullest. I owe him much, and for this he has my deepest gratitude and greatest respect. vii List of Included Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. VI I Henrik Lundgren, David Lundberg, Johan Nielsen, Erik Nordström and Christian Tschudin, A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations. In Proceedings of The Third Annual IEEE Wireless Commmunications & Networking Conference (WCNC), March II Henrik Lundgren, Erik Nordström and Christian Tschudin, Coping with Communication Gray Zones in IEEE b based Ad hoc Networks. In Proceedings of The Fifth ACM International Workshop on Wireless Mobile Multimedia (WoWMoM), September III Erik Nordström, Per Gunningberg and Christian Tschudin, Robust and Flexible Internet Connectivity for Mobile Ad hoc Networks. An extended version of the paper: Comparison of Forwarding Strategies in Internet Connected MANETs, published in ACM SIGMOBILE Mobile Computing and Communications Review (MC 2 R), Volume 8, Issue 4, Pages 72-76, October IV Christian Tschudin, Per Gunningberg, Henrik Lundgren and Erik Nordström, Lessons from Experimental MANET Research. In Elsevier Journal on Ad hoc Networks, Volume 3, Issue 2, Pages , March V Erik Nordström, Per Gunnningberg and Henrik Lundgren, A Testbed and Methodology for Experimental Evaluation of Mobile Ad hoc Networks. In Proceedings of The First International Conference on Testbeds and Research Infrastructures for the Development of Networks and Communities (TRIDENTCOM), February Erik Nordström, Per Gunningberg, Christian Rohner and Oskar Wibling, A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks. Technical Report , Uppsala University, April VII Erik Nordström, Per Gunningberg, Christophe Diot and Augustin Chaintreau, Interest-based Content Dissemination in Opportunistic Networks. To be submitted for publication. ix VIII Erik Nordström, Per Gunningberg, Christian Rohner, A Search-based Network Architecture for Content-oriented and Opportunistic Communication. Submitted for publication. Reprints are made with permissions from the publishers. Comments on my Participation Paper I: This paper is based on the work I did on the APE testbed in collaboration with Mattis Fjällström and David Lundberg. I developed large parts of the testbed and I invented the virtual mobility metric presented in the paper. It was developed further in discussions with the other authors. Paper II: I came up with the ideas behind this paper during my implementation work with the AODV protocol. They were then developed in discussions with Henrik Lundgren and Christian Tschudin. The experimental results were produced by myself and Henrik Lundgren, who then took the role as lead author of the paper. Paper III: I am the principal author of this paper. I came up with the ideas behind it and produced all the results myself. I developed and discussed the ideas with my co-authors. Paper IV: I co-authored this paper, and specifically wrote the sections on the testbed and implementation experiences. Paper V: I am the main author of this paper, and I participated in all parts of the work behind it. I formulated the methodologies described in discussions with my co-authors. Paper VI: I implemented the AODV and DSR protocols that are evaluated in this paper. I participated in all parts of the experimental work and results analysis. I am the main author of this paper. Paper VII: I am the main author of this paper. I took the lead on the work of collecting two of the three data sets used in the paper, and performed the analysis. I developed and implemented the simulator used to produce the results. Paper VIII: I am the principal author of this paper. I developed the architecture described in the paper in collaboration with Christian Rohner. I also did a majority of the implementation work, and helped with the measurements. x Other Work In addition to the papers above, the following papers, posters, demos and workshops, represent work that I have participated in, presented, authored or co-authored. 1. Erik Nordström, Christophe Diot, Richard Gass, Per Gunningberg, Experiences from Measuring Human Mobility using Bluetooth Inquiring Devices, MobiEval 2007, San Juan, Puerto Rico. 2. Erik Nordström, Per Gunningberg, Christian Rohner, Oskar Wibbling Evaluating Wireless Multi-hop Networks Using a Combination of Simulation, Emulation, and Real World Experiments, MobiEval 2007, San Juan, Puerto Rico. 3. Erik Nordström, Per Gunningberg, Christian Rohner, Oskar Wibling A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks, Presentation at Intimate workshop, July 2007, Paris, France. 4. Christian Rohner, Erik Nordström, Per Gunningberg, Christian Tschudin, Interactions between TCP, UDP and Routing Protocols in Wireless Multihop Ad hoc Networks, IEEE ICPS Workshop on Multi-hop Ad hoc Networks: from theory to reality. REALMAN 2005, Santorini, Greece. 5. Erik Nordström, Richard Gold, Per Gunningberg, Mythbusters: Whatever You Thought About MANET Routing, Think Again... , Technical Report , Department of Information Technology, Uppsala University, November Christian Rohner, Erik Nordström, Henrik Lundgren, Using Ad hoc Networking in Orienteering, Demo at the 10th Annual International Conference on Mobile Computing and Networking (MobiCom), September 2004, Philadelphia, USA. 7. Erik Nordström, Per Gunningberg, Christian Tschudin, POSTER: Comparison of Forwarding Strategies in Internet Connected MANETs, Mobi- Hoc 2004, Tokyo, Japan. 8. Christian Tschudin, Henrik Lundgren, Erik Nordström, Embedding MANETs in the Real World, PWC 2003, Venice, Italy. 9. Henrik Lundgren, Erik Nordström, Christian Tschudin, The Gray Zone Problem in IEEE b based Ad hoc Networks, ACM SIGMOBILE Mobile Computing and Communications Review The first AODV Next Generation (AODVng) workshop, in conjunction with the SIGMOBILE MobiHoc Symposium in Lausanne, Switzerland, June The first AODV Interop, held at the University of California Santa Barbara, USA, March Henrik Lundgren, David Lundberg, Johan Nielsen, Erik Nordström, Christian Tschudin, A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations, Technical Report , Department of Information Technology, Uppsala University, November xi Contents 1 Introduction Communication Protocols and Requirements Examples of Communication Challenges Research Issues and Topics New Networking Paradigms Heterogeneity: Compatibility and Interconnection Configuration and Deployment Testing and Evaluation Research Issues Addressed in this Thesis Background and Motivation Issue 1: Repeatability in Real World Experiments Issue 2: Cross-environment Evaluation Methodologies Issue 3: Real World Performance Problems Issue 4: Novel Communication Architectures Contributions Research Results Implementations and Prototypes Standardization work Unchallenged Networking Switching Packets or Circuits? A Layered Architecture Intelligence on the Edge A Hierarchy of Networks Internet Routing Naming and Addressing Challenged Networking The Unshackling of the Internet Radio Frequency Communication Signal Propagation Effects Signal Propagation Ranges Shared Medium Transmission Wireless Link Technologies WiFi - IEEE Bluetooth - IEEE Other Wireless Link Technologies Challenges in Tetherless Communication 3.4.1 Wireless Factors Mobility Multi-hop Communication Routing Sensing Disruptions and Disconnections Naming and Addressing Architectures Evaluation and Experimentation Summary and Conclusions Summaries of Included Papers Paper I: A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations Paper II: Coping with Communication Gray Zones in IEEE b based Ad hoc Networks Paper III: Robust and Flexible Internet Connectivity for Mobile Ad hoc Networks Paper IV: Lessons from Experimental MANET Research Paper V: A Testbed and Methodology for Experimental Evaluation of Mobile Ad hoc Networks Paper VI: A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks Paper VII: Interest-based Content Dissemination in Opportunistic Networks Paper VIII: A Search-based Network Architecture for Contentoriented and Opportunistic Communication Conclusions and Future Work Summary in Swedish Paper I: A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations Introduction APE Architecture and Implementation Choreography and Data Traffic Generation Data Gathering Tools Data Analysis Tools Testbed Distribution Capturing Mobility in Ad hoc Networks A Virtual Mobility Metric Experimental Set-up Physical Environment Scenario Descriptions First Results vm Analysis Packet Loss and Hop Count Analysis xiv 6 Summary and Future Work Paper II: Coping with Communication Gray Zones in IEEE b based Ad hoc Networks Introduction Communication Gray Zones Performance Problems of Original AODV Conditions for the Forming of Communication Gray Zones The Shape of Communication Gray Zones Unrealistic ns-2 simulations Eliminating Gray Zones Exchanging Neighbor Sets N Consecutive HELLOs SNR Threshold for Control Packets Results Ping Delivery Success Continuous MP3 Streaming Intermittent HTTP Requests Discussion Comparison Against OLSR and LUNAR Protocols without Gray Zone Problem IEEE b is not Bidirectional Conclusions Paper III: Robust and Flexible Internet Connectivity for Mobile Ad hoc Networks Introduction Problem Diagnosis Related Work Internet drafts Evaluations of Systems Overview of MANET Internet Connectivity Destination Locality Gateway Discovery Forwarding Robust and Flexible Internet Connectivity Implementation Details Evaluation Simulation Results Experimental Results Conclusions Paper IV: Lessons from Experimental MANET Research Introduction MANET Research Approach Implementation Experimentation xv 2.3 Integration Lessons from Experimental Research within the IETF MANET Area APE Testbed Reproducible Real World Testing AODV-UU Protocol Implementation Gray Zones Reality Complements Simulation The Ad Hoc Horizon Focus on Achievable Goals Lessons from Research Outside the IETF MANET Area LUNAR Targeting Simplicity Cross-Layer Optimization Between Link and Transport Layer Challenges to Ad Hoc Networking Dependence upon Link Layer Technology Limiting the Problem Space Outlook Paper V: A Testbed and Methodology for Experimental Evaluation of Wireless Mobile Ad hoc Networks Introduction Simulation, Emulation and Real World Related Work Methodology The APE Testbed Software Overview Experiment Design Measurements and Data Gathering Assessing Repeatability Topological Replay Assessment Metrics Assessment Example Experiment Example: Routing Protocol Comparisons and the Gray Zone effect Discussion and Conclusions Paper VI: A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks Introduction Experimental Setup and Methodology Coupling the Real World, Emulation and Simulation Traffic Configuration Scenario Descriptions Routing Protocols Evaluation Measurements and Metrics Performance when Varying the Evaluation Environment Performance of Sensing Mechanisms xvi 4 Related Work Conclusions Paper VII: Interest-based Content Dissemination in Opportunistic Networks Introduction Related Work Content Dissemination Model The Node Profile Communities and Content Matching Experimental Data Sets Contact Data Sets Sociology of the Data Sets Interest Information Methodology Implementation Simulator Setup Dissemination Strategies Performance Metrics Results Performance from Contact Trace Impact of Interest Semantic Community Collaboration Community Size Dissemination Cost Delay and Path Length Discussion and Conclusion Paper VIII: A Search-based Network Architecture for Content-oriented and Opportunistic Communication Introduction Design Overview Desktop Searching Unified Metadata Namespace Search-based Networking Primitives Persistent and Searchable Storage Dissemination and Event Notification Searching as a Networking Abstraction The Haggle Architecture The Core System The Managers Implementation Evaluation Methodology and Experimental Setup Results Related Work xvii xviii 7 Discussion and Conclusions 1. Introduction This thesis is concerned with the design, implementation and evaluation of communication protocols for challenged networks 1. They are interesting from a communication perspective because they in many respects fundamentally change, or challenge, many established principles and assumptions in today s communication networks most notably the Internet. This has implications for the design, implementation, and evaluation of communication protocols, and requires us to think in new ways about how to approach computer communication. Challenged networks have emerged mainly as a result of developments in wireless and mobile communication technologies during the past couple of decades. Examples include wireless and mobile ad hoc networks (MANETs), wireless sensor networks (WSNs) consisting of small embedded sensor devices, and delay and disruption tolerant networks (DTNs) that allow posta
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