In this paper, we propose to use coordinates-based mechanisms in a peer-to-peer architecture to predict Internet network distance (i.e. round-trip propagation and transmission delay) . We study two mechanisms. The first is a previously proposed scheme, called the triangulated heuristic, which is based on relative coordinates that are simply the distances from a host to some special network nodes. We propose the second mechanism, called Global Network Positioning (GNP), which is based on absolute coordinates computed from modeling the Internet as a geometric space. Since end hosts maintain their own coordinates, these approaches allow end hosts to compute their inter-host distances as soon as they discover each other. Moreover coordinates are very efficient in summarizing inter-host distances, making these approaches very scalable. By performing experiments using measured Internet distance data, we show that both coordinates-based schemes are more accurate than the existing state of the art system IDMaps, and the GNP approach achieves the highest accuracy and robustness among them.

While application end-point architectures have proven to be viable solutions for large-scale distributed applications such as distributed computing and file-sharing, there is little known about its feasibility for more bandwidth-demanding applications such as live streaming. Heterogeneity in bandwidth resources and dynamic group membership, inherent properties of application end-points, may adversely affect the construction of a usable and efficient overlay. At large scales, the problems become even more challenging. In this paper, we study one of the most prominent architectural issues in overlay multicast: the feasibility of supporting large-scale groups using an application end-point architecture. We look at three key requirements for feasibility: (i) are there enough resources to construct an overlay, (ii) can a stable and connected overlay be maintained in the presence of group dynamics, and (iii) can an efficient overlay be constructed? Using traces from a large content delivery network, we characterize the behavior of users watching live audio and video streams. We show that in many common real-world scenarios, all three requirements are satisfied. In addition, we evaluate the performance of several design alternatives and show that simple algorithms have the potential to meet these requirements in practice. Overall, our results argue for the feasibility of supporting largescale live streaming using an application end-point architecture.

In this paper, we report on experience in building and deploying an operational Internet broadcast system based on Overlay Multicast. In over a year, the system has been providing a cost-e#ective alternative for Internet broadcast, used by over 3600 users spread across multiple continents in home, academic and commercial environments. Technical conferences and special interest groups are the early adopters. Our experience confirms that Overlay Multicast can be easily deployed and can provide reasonably good application performance. The experience has led us to identify first-order issues that are guiding our future e#orts and are of importance to any Overlay Multicast protocol or system. Our key contributions are (i) enabling a real Overlay Multicast application and strengthening the case for overlays as a viable architecture for enabling group communication applications on the Internet, (ii) the details in engineering and operating a fully functional streaming system, addressing a wide range of real-world issues that are not typically considered in protocol design studies, and (iii) the data, analysis methodology, and experience that we are able to report given our unique standpoint.

(PRM): a multicast data recovery scheme that improves data delivery ratios while maintaining low end-to-end latencies. PRM has both a proactive and a reactive components; in this paper we describe how PRM can be used to improve the performance of application-layer multicast protocols especially when there are high packet losses and host failures. Through detailed analysis in this paper, we show that this loss recovery technique has efficient scaling properties—the overheads at each overlay node asymptotically decrease to zero with increasing group sizes. As a detailed case study, we show how PRM can be applied to the NICE application-layer multicast protocol. We present detailed simulations of the PRM-enhanced NICE protocol for 10 000 node Internet-like topologies. Simulations show that PRM achieves a high delivery ratio ( 97%) with a low latency bound (600 ms) for environments with high end-to-end network losses (1%–5%) and high topology change rates (5 changes per second) while incurring very low overheads ( 5%). Index Terms—Multicast, networks, overlays, probabilistic forwarding, protocols, resilience. I.

Abstract — Many algorithms for routing in sensor networks exploit greedy forwarding strategies to get packets to their destinations. In this paper we study a fundamental difficulty such strategies face: the “local minimum phenomena ” that can cause packets to get stuck. We give a definition of stuck nodes where packets may get stuck in greedy multi-hop forwarding, and develop a local rule, the TENT rule, for each node in the network to test whether a packet can get stuck at that node. To help the packets get out of stuck nodes, we describe a distributed algorithm, BOUNDHOLE, to build routes around holes, which are connected regions of the network with boundaries consisting of all the stuck nodes. We show that these hole-surrounding routes can be used in many applications such as geographic routing, path migration, information storage mechanisms and identification of regions of interest.

We propose an application level multicast approach, Topology Aware Grouping (TAG), which exploits underlying network topology information to build efficient overlay networks among multicast group members. TAG uses information about path overlap among members to construct a tree that reduces the overlay relative delay penalty, and reduces the number of duplicate copies of a packet on the same link. We study the properties of TAG, and model and experiment with its economies of scale factor to quantify its benefits compared to unicast and IP multicast. We also compare the TAG approach with the ESM approach in a variety of simulation configurations including a number of real Internet topologies and generated topologies. Our results indicate the effectiveness of our heuristic algorithm in reducing delays and duplicate packets, with reasonable time and space complexities.

Peer-to-peer technologies have proved to be effective for various bandwidth intensive, large scale applications such as file-transfer. For many years, there has been tremendous interest in academic environments for live video streaming as another application of P2P. Recently, a number of new commercial scale video streaming systems have cropped up. These systems differ from others in the type of content that they provide and attract a large number of users from across the globe. These are proprietary systems and very little is known about their architecture and behavior. This study is one of the first of its kind to analyze the performance and characteristics of P2P live streaming applications. In particular, we analyze PPLive and SOPCast, two of the most popular systems in this class. In this paper, we (1) present a framework in which to analyze these P2P applications from a single observable point, (2) analyze control traffic to present a probable operation model and (3) present analysis of resource usage, locality and stability of data distribution. We conclude that P2P live streaming has an even greater impact on network bandwidth utilization and control than P2P file transfer applications.

The growing popularity of aspect-oriented languages, such as AspectJ, and of corresponding design approaches, makes it important to learn how best to modularize programs in which aspect-oriented composition mechanisms are used. We contribute an approach to information hiding modularity in programs that use quantified advising as a module composition mechanism. Our approach rests on a new kind of interface: one that abstracts a crosscutting behavior, decouples the design of code that advises such a behavior from the design of the code to be advised, and that can stipulate behavioral contracts. Our interfaces establish design rules that govern how specific points in program execution are exposed through a given join point model and how conforming code on either side should behave. In a case study of the HyperCast overlay network middleware system, including a real options analysis, we compare the widely cited oblivious design approach with our own, showing significant weaknesses in the former and benefits in the latter.

All of the advantages of application-layer overlay networks arise from two fundamental properties: (1) The network nodes in an overlay network, as opposed to lower-layer network elements such as routers and switches, are end systems and have capabilities far beyond basic operations of storing and forwarding; and (2) The overlay topology, residing above a densely connected IP-layer wide-area network, can be constructed and manipulated to suit one's purposes. In this paper, we seek to significantly...

As the Internet is expected to better support multimedia applications, new services need to be deployed. One of them is the group communication service for one-tomany or many-to-many data delivery. After more than a decade of important research and development efforts, the deployment of multicast routing in the Internet is far behind expectations. Therefore, a first motivation for an alternative group communication service is to bypass the lack of native IP multicast routing. Although less efficient and scalable than native multicast routing, such alternative services are suitable for the purpose. A second possible motivation is to go beyond the limitations of classic multicast routing for very specific working environments. In this article we identify, classify, and discuss some of these alternative approaches. Agroup communication service refers to the ability to send information to several receivers at the same time, using either a one-to-many or many-tomany model. The any-source and source-specific