Abstract — Peer-to-peer content distribution has become a major source of bandwidth costs for Internet service providers (ISPs). One way for ISPs to decrease these costs is to deploy caches for p2p traffic. To make efficient use of the caches, in this paper we propose a cooperative caching and relaying scheme that is compatible with the existing business relations between ISPs. We formulate the problem of cooperative caches as a resource allocation problem, and show that it is related to the problem of r-configuration studied in graph theory. We propose a distributed algorithm to solve the resource allocation problem, and show that cooperation leads to significant gains compared to noncooperative caching. I.

Abstract—In large-scale peer-to-peer (P2P) live streaming systems with a limited supply of server bandwidth, increasing the amount of upload bandwidth supplied by peers becomes critically important to the “well being ” of streaming sessions in live channels. Intuitively, two types of peers are preferred to be kept up in a live session: peers that contribute a higher percentage of their upload capacities, and peers that are stable for a long period of time. The fundamental challenge is to identify, and satisfy the needs of, these types of “superior ” peers in a live session, and to achieve this goal with minimum disruption to the traditional pull-based protocols that real-world live streaming protocols use. In this paper, we conduct a comprehensive and in-depth statistical analysis based on more than 130 GB worth of runtime traces from hundreds of streaming channels in a largescale real-world live streaming system, UUSee (among the top three commercial systems in popularity in mainland China). Our objective is to discover critical factors that may influence the longevity and bandwidth contribution ratio of peers, using survival analysis techniques such as the Cox proportional hazards model and the Mantel-Haenszel test. Once these influential factors are found, they can be used to form a superiority index to distill superior peers from the general peer population. The index can be used in any way to favor superior peers, and we simulate the use of a simple ranking mechanism in a natural selection algorithm to show the effectiveness of the index, based on a replay of real-world traces from UUSee. I.

The two main sources of impairment in overlay multicast systems are packet losses and node churn. Yet, little is known about their effects on the data distribution performance. In this paper we develop an analytical model of a large class of peer-to-peer streaming architectures based on decomposition and non-linear recurrence relations. We analyze the stability properties of these systems using fixed-point analysis. We derive bounds on the probability that nodes in the overlay receive an arbitrary packet of the stream. Based on the model, we explain the effects of the overlay’s size, node heterogeneity, loss correlations and node churn on the overlay’s performance. Our findings lead us to the definition of an overlay structure with improved stability properties. We show how and under what conditions overlays can benefit from the use of error control solutions, prioritization and taxation schemes. Based on our results, we identify the components that are needed to achieve good data distribution performance in multi-tree-based overlay multicast.

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Abstract—A major challenge for real-time streaming overlays is to distribute high bit-rate streams with uninterrupted playback. Hosts usuallyhave sufficient inbound bandwidthtosupport streaming, but due to the prevalence of asymmetric links in broadband networks, the bottleneck is the aggregate, overlaywide outbound bandwidth. If this bandwidth is less than what is required to forward the stream to the overlay members, then a large number of users potentially experience poor playback. We argue that for successful streaming in bandwidth constrained situations overlays need to be able to adapt to the aggregate available bandwidth. We present four bandwidth adaptation policies for tree-based streaming overlays and evaluate their efficiency using a large-scale emulation testbed with realistic broadband link characteristics. I.

This paper presents a queueing model to evaluate the latency associated with file transfers or replications in peer to peer (P2P) computer systems. The main contribution of this paper is a modeling framework for the peers that accounts for the file size distribution, the search time, load distribution at peers and number of concurrent downloads allowed by a peer. We propose a queueing model that models the nodes or peers in such systems as M/G/1/K processor sharing queues. The model is extended to account for peers which alternate between online and offline states. The proposed queueing model for the peers is combined with a single class open queueing network for the routers interconnecting the peers to obtain the overall file transfer latency. We also show that in scenarios with multi-part downloads from different peers, a rate proportional allocation strategy minimizes the download times.

Large-scale live peer-to-peer (P2P) streaming applications have been successfully deployed in today’s Internet. While they can accommodate hundreds of thousands of users simultaneously with hundreds of channels of programming, there still commonly exist channels and times where and when the streaming quality is unsatisfactory. In this paper, based on more than two terabytes and one year worth of live traces from UUSee, a large-scale commercial P2P live streaming system, we show an in-depth network-wide diagnosis of streaming inefficiencies, commonly present in typical mesh-based P2P live streaming systems. As the first highlight of our work, we identify an evolutionary pattern of low streaming quality in the system, and the distribution of streaming inefficiencies across various streaming channels and in different geographical regions. We then carry out an extensive investigation to explore the causes to such streaming inefficiencies over different times and across different channels/regions at specific times, by investigating the impact of factors such as the number of peers, peer upload bandwidth, inter-peer bandwidth availability, server bandwidth consumption, and many more. The original discoveries we have brought forward include the two-sided effects of peer population on the streaming quality in a streaming channel, the significant impact of inter-peer bandwidth bottlenecks at peak times, and the inefficient utilization of server capacities across concurrent channels. Based on these insights, we identify problems within the existing P2P live streaming design and discuss a number of suggestions to improve real-world streaming protocols operating at a large scale.

In a peer to peer streaming system, the server usually provides multiple channels. Peers may form multiple groups, each corresponding to a channel for content distribution. A peer can freely switch from one channel to another. We propose a shared or distributed overlay framework (called SMesh or subset mesh) for dynamic groups where users may frequently hop between different groups. SMesh first builds a relatively stable mesh consisting of all hosts for control messaging and supports dynamic joining and leaving host in between the groups. And will guide the construction of overlay delivery trees. Through simulations on Internet, we show that SMesh achieves low delay and low link stress with efficient and low cost maintenance. Secondly we focus on providing statistically guaranteed streaming quality at channel level and individual peer level.

Abstract — In order to improve scalability and reduce maintenance overhead for Peer-to-Peer system, several architecture with constant degree and optimal diameter are proposed. However, the expected topology doesn’t effectively utilize the bandwidth capacity of peers. In this work, we propose K-overlay, an overlay scheme based on unbalanced Kautz graph with logd n diameter and constant in-degree. We define the degree of a digraph as the maximum number of arcs arriving at or leaving from any vertex. The diameter of a graph is the number of arc traversals that is sufficient to reach any vertex from any other vertex. K-overlay structure is based on two-fold mechanism. (1) Organization of peers in concentric circles to maximize the outgoing bandwidth of peers (2) Content delivery through parent as well as neighboring peers. Through formal analysis and comprehensive simulations, we show that our proposed architecture achieves optimal diameter and good connectivity as compared to existing overlay architecture like P2Cast.

Abstract — In order to improve scalability and reduce maintenance overhead for Peer-to-Peer system, several architecture with constant degree and optimal diameter are proposed. However, the expected topology doesn’t effectively utilize the bandwidth capacity of peers. In this work, we propose K-overlay, an overlay scheme based on unbalanced Kautz graph with logd n diameter and constant in-degree. We define the degree of a digraph as the maximum number of arcs arriving at or leaving from any vertex. The diameter of a graph is the number of arc traversals that is sufficient to reach any vertex from any other vertex. K-overlay structure is based on two-fold mechanism. (1) Organization of peers in concentric circles to maximize the outgoing bandwidth of peers (2) Content delivery through parent as well as neighboring peers. Through formal analysis and comprehensive simulations, we show that our proposed architecture achieves optimal diameter and good connectivity as compared to existing overlay architecture like P2Cast.