In recent years, overlay networks have become an effective alternative to IP multicast for efficient point to multipoint communication across the Internet. Typically, nodes self-organize with the goal of forming an efficient overlay tree, one that meets performance targets without placing undue burden on the underlying network. In this paper, we target high-bandwidth data distribution from a single source to a large number of receivers. Applications include large-file transfers and real-time multimedia streaming. For these applications, we argue that an overlay mesh, rather than a tree, can deliver fundamentally higher bandwidth and reliability relative to typical tree structures. This paper presents Bullet, a scalable and distributed algorithm that enables nodes spread across the Internet to self-organize into a high bandwidth overlay mesh. We construct Bullet around the insight that data should be distributed in a disjoint manner to strategic points in the network. Individual Bullet receivers are then responsible for locating and retrieving the data from multiple points in parallel. Key contributions of this work include: i) an algorithm that sends data to di#erent points in the overlay such that any data object is equally likely to appear at any node, ii) a scalable and decentralized algorithm that allows nodes to locate and recover missing data items, and iii) a complete implementation and evaluation of Bullet running across the Internet and in a large-scale emulation environment reveals up to a factor two bandwidth improvements under a variety of circumstances. In addition, we find that, relative to tree-based solutions, Bullet reduces the need to perform expensive bandwidth probing.

Internet radio and television stations require significant bandwidth to support delivery of high quality audio and video streams to a large number of receivers. IP multicast is an appropriate delivery model for these applications. However, widespread deployment of IP multicast on the Internet is unlikely in the near future. An alternative is to build a multicast tree in the application layer. Previous studies have addressed tree construction in the application layer. However, most of them focus on reducing delay.

In the age of multimedia and high-sl)eed networks', multicast is one of the mechanisms by which the power of the Internet can be further harnessed in an efficient manner. When more than one receiver is interested in receiving a transmission from a single or a set of senders, multicast is the most efficient and viable mechanism. In the protocol stack of the network, multicast is best implemented in the network layer in the form of a multicast routing protocol to select the best path for the transmission. The other layers' of the protocol stack provide additional features for multicast.

Many grid applications need to transfer large amounts of data between the geographically distributed sites of a grid environment. Network heterogeneity between these sites makes throughput optimization of data transfers to multiple sites (multicast) hard or even impossible. We present a technique called balanced multicasting that uses monitoring information for both bandwidth capacity and achievable bandwidth to compute balanced multicast trees at runtime that use application-level traffic shaping at the sender side to avoid self-induced congestion. Our experimental evaluation shows that our approach outperforms existing multicast strategies by large margins. 1.

Although initially proposed as the deployable alternative to IP multicast, overlay multicast actually offers us great flexibilities on QoS-aware resource allocation for network applications. For example, in overlay multicast streaming, (1) the streaming rate of each client can be diversified to better accommodate network heterogeneity, through various end-toend streaming adaptation techniques; and (2) one can freely organize the overlay session by rearranging the multicast tree, for the purpose of better resource utilization and fairness among all clients. The goal of this paper, is to find the max-min rate allocation in overlay multicast, which is pareto-optimal in terms of network resource utilization, and max-min fair. We approach this goal in two steps. First, we present a distributed algorithm, which is able to return the max-min rate allocation for any given overlay multicast tree. Second, we study the problem of finding the optimal tree, whose max-min rate allocation is optimal among all trees. After proving its NP-hardness, we propose a heuristic algorithm of overlay multicast tree construction. A variation of the heuristic is also designed to handle the dynamic client join/departure. Both of them have approximation bound of 1/2 to the optimal value. Experimental results show that they achieve high average throughput, almost saturate link utilization, and consistent min-favorability.

Multicast avoids sending repeated packets over the same network links and thus offers the promise of supporting multimedia streaming over wide-area networks. Previously, two opposite multicast schemes – forward-path forwarding and reverse-path forwarding – have been proposed on top of structured peer-to-peer (p2p) overlay networks. This paper presents Borg, a new scalable application-level multicast system built on top of p2p overlay networks. Borg is a hybrid protocol that exploits the asymmetry in p2p routing and leverages the reverse-path multicast scheme for its low link stress on the physical networks. Borg has been implemented on top of Pastry, a generic, structured p2p routing substrate. Simulation results based on a realistic network topology model shows that Borg induces significantly lower routing delay penalty than both forward-path and reversepath multicast schemes while retaining the low link stress of the reverse-path multicast scheme. 1.

Grid applications often need to distribute large amounts of data efficiently from one cluster to multiple others (multicast). Existing methods usually arrange nodes in optimized tree structures, based on external network monitoring data. This dependence on monitoring data, however, severely impacts both ease of deployment and adaptivity to dynamically changing network conditions. In this paper, we present Multicast Optimizing Bandwidth (MOB), a high-throughput multicast approach, inspired by the BitTorrent protocol [4]. With MOB, data transfers are initiated by the receivers that try to steal data from peer clusters. Instead of using potentially outdated monitoring data, MOB automatically adapts to the currently achievable bandwidth ratios. Our experimental evaluation compares MOB to both the BitTorrent protocol and to our previous approach, Balanced Multicasting [11], the latter optimizing multicast trees based on external monitoring data. We show that MOB outperforms the BitTorrent protocol. MOB is competitive with Balanced Multicasting as long as the network bandwidth remains stable. With dynamically changing bandwith, MOB outperforms Balanced Multicasting by wide margins.

This article focuses on the multireceiver data dissemination problem. Initially, IP multicast formed the basis for efficiently supporting such distribution. More recently, overlay networks have emerged to support point-to-multipoint communication. Both techniques focus on constructing trees rooted at the source to distribute content among all interested receivers. We argue, however, that trees have two fundamental limitations for data dissemination. First, since all data comes from a single parent, participants must often continuously probe in search of a parent with an acceptable level of bandwidth. Second, due to packet losses and failures, available bandwidth is monotonically decreasing down the tree. To address these limitations, we present Bullet, a data dissemination mesh that takes advantage of the computational and storage capabilities of end hosts to create a distribution structure where a node receives data in parallel from multiple peers. For the mesh to deliver improved bandwidth and reliability, we need to solve several key problems: (i) disseminating disjoint data over the mesh, (ii) locating missing content, (iii) finding who to peer with (peering strategy), (iv) retrieving data at the

Abstract—In recent years, there has been an increasing interest in peer-to-peer (P2P) multimedia streaming. In this paper, we consider constructing a high-bandwidth overlay tree for streaming services. We observe that underlay information such as link connectivity and link bandwidth is important in tree construction, because two seemingly disjoint overlay paths may share common links on the underlay. We hence study how to construct a high-bandwidth overlay tree given the underlay topology. We formulate the problem as building a Maximum Bandwidth Multicast Tree (MBMT) or a Minimum Stress Multicast Tree (MSMT), depending on whether link bandwidth is available or not. We prove that both problems are NP-hard and are not approximable within a factor of @P QC A, for any H, unless ax€. We then present approximation algorithms to address them and analyze the algorithm performance. Furthermore, we discuss some practical issues (e.g., group dynamics, resilience and scalability) in system implementation. We evaluate our algorithms on Internet-like topologies. The results show that our algorithms can achieve high tree bandwidth and low link stress with low penalty in end-to-end delay. Measurement study based on PlanetLab further confirms this. Our study shows that the knowledge of underlay is important for constructing efficient overlay trees. Index Terms—Overlay tree, peer-to-peer streaming, topologyaware, tree bandwidth. I.

Research on the construction of logical overlay networks has gained significance in recent times. This is partly due to work on peer-to-peer (P2P) systems for locating and retrieving distributed data objects, and also scalable content distribution using end-system multicast techniques. However, there are emerging applications that require the real-time transport of data from various sources to potentially many thousands of subscribers, each having their own quality-of-service (QoS) constraints. This paper primarily focuses on the properties of two popular topologies found in interconnection networks, namely k-ary n-cubes and de Bruijn graphs. The regular structure of these graph topologies makes them easier to analyze and determine possible routes for real-time data than complete or irregular graphs. We show how these overlay topologies compare in their ability to deliver data according to the QoS constraints of many subscribers, each receiving data from specific publishing hosts. Comparisons are drawn on the ability of each topology to route data in the presence of dynamic system effects, due to end-hosts joining and departing the system. Finally, experimental results show the service guarantees and physical link stress resulting from efficient multicast trees constructed over both kinds of overlay networks.