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487
Handling Churn in a DHT
- In Proceedings of the USENIX Annual Technical Conference
, 2004
"... This paper addresses the problem of churn---the continuous process of node arrival and departure---in distributed hash tables (DHTs). We argue that DHTs should perform lookups quickly and consistently under churn rates at least as high as those observed in deployed P2P systems such as Kazaa. We then ..."
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Cited by 450 (22 self)
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This paper addresses the problem of churn---the continuous process of node arrival and departure---in distributed hash tables (DHTs). We argue that DHTs should perform lookups quickly and consistently under churn rates at least as high as those observed in deployed P2P systems such as Kazaa. We then show through experiments on an emulated network that current DHT implementations cannot handle such churn rates. Next, we identify and explore three factors affecting DHT performance under churn: reactive versus periodic failure recovery, message timeout calculation, and proximity neighbor selection. We work in the context of a mature DHT implementation called Bamboo, using the ModelNet network emulator, which models in-network queuing, cross-traffic, and packet loss. These factors are typically missing in earlier simulationbased DHT studies, and we show that careful attention to them in Bamboo's design allows it to function effectively at churn rates at or higher than that observed in P2P file-sharing applications, while using lower maintenance bandwidth than other DHT implementations.
I Tube, You Tube, Everybody Tubes: Analyzing the World’s Largest User Generated Content Video System
- In Proceedings of the 5th ACM/USENIX Internet Measurement Conference (IMC’07
, 2007
"... User Generated Content (UGC) is re-shaping the way people watch video and TV, with millions of video producers and consumers. In particular, UGC sites are creating new viewing patterns and social interactions, empowering users to be more creative, and developing new business opportunities. To better ..."
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Cited by 373 (7 self)
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User Generated Content (UGC) is re-shaping the way people watch video and TV, with millions of video producers and consumers. In particular, UGC sites are creating new viewing patterns and social interactions, empowering users to be more creative, and developing new business opportunities. To better understand the impact of UGC systems, we have analyzed YouTube, the world’s largest UGC VoD system. Based on a large amount of data collected, we provide an in-depth study of YouTube and other similar UGC systems. In particular, we study the popularity life-cycle of videos, the intrinsic statistical properties of requests and their relationship with video age, and the level of content aliasing or of illegal content in the system. We also provide insights on the potential for more efficient UGC VoD systems (e.g. utilizing P2P techniques or making better use of caching). Finally, we discuss the opportunities to leverage the latent demand for niche videos that are not reached today due to information filtering effects or other system scarcity distortions. Overall, we believe that the results presented in this paper are crucial in understanding UGC systems and can provide valuable information to ISPs, site administrators, and content owners with major commercial and technical implications. Categories and Subject Descriptors Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.
The Changing Usage of a Mature Campus-wide Wireless Network
- In Proceedings of ACM MOBICOM
, 2004
"... Wireless Local Area Networks (WLANs) are now commonplace on many academic and corporate campuses. As "Wi-Fi" technology becomes ubiquitous, it is increasingly important to understand trends in the usage of these networks. ..."
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Cited by 322 (12 self)
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Wireless Local Area Networks (WLANs) are now commonplace on many academic and corporate campuses. As "Wi-Fi" technology becomes ubiquitous, it is increasingly important to understand trends in the usage of these networks.
A Survey and Comparison of Peer-to-Peer Overlay Network Schemes
- IEEE COMMUNICATIONS SURVEYS AND TUTORIALS
, 2005
"... Over the Internet today, computing and communications environments are significantly more complex and chaotic than classical distributed systems, lacking any centralized organization or hierarchical control. There has been much interest in emerging Peer-to-Peer (P2P) network overlays because they ..."
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Cited by 302 (1 self)
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Over the Internet today, computing and communications environments are significantly more complex and chaotic than classical distributed systems, lacking any centralized organization or hierarchical control. There has been much interest in emerging Peer-to-Peer (P2P) network overlays because they provide a good substrate for creating large-scale data sharing, content distribution and application-level multicast applications. These P2P networks try to provide a long list of features such as: selection of nearby peers, redundant storage, efficient search/location of data items, data permanence or guarantees, hierarchical naming, trust and authentication, and, anonymity. P2P networks potentially offer an efficient routing architecture that is self-organizing, massively scalable, and robust in the wide-area, combining fault tolerance, load balancing and explicit notion of locality. In this paper, we present a survey and comparison of various Structured and Unstructured P2P networks. We categorize the various schemes into these two groups in the design spectrum and discuss the application-level network performance of each group.
The Bittorrent P2P File-Sharing System: Measurements and Analysis
- 4TH INTERNATIONAL WORKSHOP ON PEER-TO-PEER SYSTEMS (IPTPS)
, 2005
"... Of the many P2P file-sharing prototypes in existence, BitTorrent is one of the few that has managed to attract millions of users. BitTorrent relies on other (global) components for file search, employs a moderator system to ensure the integrity of file data, and uses a bartering technique for downlo ..."
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Cited by 280 (23 self)
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Of the many P2P file-sharing prototypes in existence, BitTorrent is one of the few that has managed to attract millions of users. BitTorrent relies on other (global) components for file search, employs a moderator system to ensure the integrity of file data, and uses a bartering technique for downloading in order to prevent users from freeriding. In this paper we present a measurement study of BitTorrent in which we focus on four issues, viz. availability, integrity, flashcrowd handling, and download performance. The purpose of this paper is to aid in the understanding of a real P2P system that apparently has the right mechanisms to attract a large user community, to provide measurement data that may be useful in modeling P2P systems, and to identify design issues in such systems.
An experimental study of the skype peer-to-peer voip system
, 2006
"... Despite its popularity, relatively little is known about the traf-fic characteristics of the Skype VoIP system and how they differ from other P2P systems. We describe an experimen-tal study of Skype VoIP traffic conducted over a one month period, where over 30 million datapoints were collected re-ga ..."
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Cited by 193 (0 self)
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Despite its popularity, relatively little is known about the traf-fic characteristics of the Skype VoIP system and how they differ from other P2P systems. We describe an experimen-tal study of Skype VoIP traffic conducted over a one month period, where over 30 million datapoints were collected re-garding the population of online clients, the number of su-pernodes, and their traffic characteristics. The results indi-cate that although the structure of the Skype system appears to be similar to other P2P systems, particularly KaZaA, there are several significant differences in traffic. The number of active clients shows diurnal and work-week behavior, corre-lating with normal working hours regardless of geography. The population of supernodes in the system tends to be rela-tively stable; thus node churn, a significant concern in other systems, seems less problematic in Skype. The typical band-width load on a supernode is relatively low, even if the su-pernode is relaying VoIP traffic. The paper aims to aid further understanding of a signifi-cant, successful P2P VoIP system, as well as provide exper-imental data that may be useful for design and modeling of such systems. These results also imply that the nature of a VoIP P2P system like Skype differs fundamentally from ear-lier P2P systems that are oriented toward file-sharing, and music and video download applications, and deserves more attention from the research community. 1
A Measurement Study of a Large-Scale P2P IPTV System
"... ... to flood Internet access and backbone ISPs with massive amounts of new traffic. We recently measured 200,000 IPTV users for a single program, receiving at an aggregate simultaneous rate of 100 gigabits/second. Although many architectures are possible for IPTV video distribution, several chunkdri ..."
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Cited by 185 (21 self)
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... to flood Internet access and backbone ISPs with massive amounts of new traffic. We recently measured 200,000 IPTV users for a single program, receiving at an aggregate simultaneous rate of 100 gigabits/second. Although many architectures are possible for IPTV video distribution, several chunkdriven P2P architectures have been successfully deployed in the Internet. In order to gain insight into chunk-driven P2P IPTV systems and the traffic loads they place on ISPs, we have undertaken an in-depth measurement study of one of the most popular IPTV systems, namely, PPLive. We have developed a dedicated PPLive crawler, which enables us to study the global characteristics of the chunk-driven PPLive system. We have also collected extensive packet traces for various different measurement scenarios, including both campus access network and residential access networks. The measurement results obtained through these platforms bring important insights into IPTV user behavior, P2P IPTV traffic overhead and redundancy, peer partnership characteristics, P2P IPTV viewing quality, and P2P IPTV design principles.
The Effect of File Sharing on Record Sales: An Empirical Analysis
- Journal of Political Economy
, 2004
"... numerous seminars, and two anonymous referees for helpful comments. This project would not have been possible without the assistance of several individuals and organizations. MixMasterFlame and the FlameNap network shared P2P data with us, and BigChampagne LLC, the CMJ Network, Nathaniel Leibowitz, ..."
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Cited by 162 (2 self)
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numerous seminars, and two anonymous referees for helpful comments. This project would not have been possible without the assistance of several individuals and organizations. MixMasterFlame and the FlameNap network shared P2P data with us, and BigChampagne LLC, the CMJ Network, Nathaniel Leibowitz, and Nevil Brownlee generously provided auxiliary data. We thank Keith Ross and David Weekly for assistance in understanding the KaZaA, OpenNap, and WinMX search protocols and database indices. Sarah Woolverton and Christina Hsiung Chen
Should Internet Service Providers Fear Peer-Assisted Content Distribution?
, 2005
"... Recently, peer-to-peer (P2P) networks have emerged as an attractive solution to enable large-scale content distribution without requiring major infrastructure investments. While such P2P solutions appear highly beneficial for content providers and end-users, there seems to be a growing concern among ..."
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Cited by 130 (3 self)
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Recently, peer-to-peer (P2P) networks have emerged as an attractive solution to enable large-scale content distribution without requiring major infrastructure investments. While such P2P solutions appear highly beneficial for content providers and end-users, there seems to be a growing concern among Internet Service Providers (ISPs) that now need to support the distribution cost. In this work, we explore the potential impact of future P2P file delivery mechanisms as seen from three different perspectives: i) the content provider, ii) the ISPs, and iii) individual content consumers. Using a diverse set of measurements including BitTorrent tracker logs and payload packet traces collected at the edge of a 20,000 user access network, we quantify the impact of peer-assisted file delivery on end-user experience and resource consumption. We further compare it with the performance expected from traditional distribution mechanisms based on large server farms and Content Distribution Networks (CDNs).
Characterizing unstructured overlay topologies in modern p2p file-sharing systems
- In Internet Measurement Conference
, 2005
"... During recent years, peer-to-peer (P2P) file-sharing systems have evolved in many ways to accommodate growing numbers of participating peers. In particular, new features have changed the properties of the unstructured overlay topology formed by these peers. Despite their importance, little is known ..."
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Cited by 120 (9 self)
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During recent years, peer-to-peer (P2P) file-sharing systems have evolved in many ways to accommodate growing numbers of participating peers. In particular, new features have changed the properties of the unstructured overlay topology formed by these peers. Despite their importance, little is known about the characteristics of these topologies and their dynamics in modern file-sharing applications. This paper presents a detailed characterization of P2P overlay topologies and their dynamics, focusing on the modern Gnutella network. Using our fast and accurate P2P crawler, we capture a complete snapshot of the Gnutella network with more than one million peers in just a few minutes. Leveraging more than 18,000 recent overlay snapshots, we characterize the graph-related properties of individual overlay snapshots and overlay dynamics across hundreds of back-to-back snapshots. We show how inaccuracy in snapshots can lead to erroneous conclusions—such as a power-law degree distribution. Our results reveal that while the Gnutella network has dramatically grown and changed in many ways, it still exhibits the clustering and short path lengths of a small world network. Furthermore, its overlay topology is highly resilient to random peer departure and even systematic attacks. More interestingly, overlay dynamics lead to an “onion-like ” biased connectivity among peers where each peer is more likely connected to peers with higher uptime. Therefore, long-lived peers form a stable core that ensures reachability among peers despite overlay dynamics. 1
