Outreach: peer-to-peer topology construction towards minimized server bandwidth costs

On-demand and live multimedia streaming applications (such as Internet TV) are well known to utilize a significant amount of bandwidth from media streaming servers, especially as the number of participating peers in the streaming session scales up. To scale to higher bit rates of media streams and larger numbers of participating peers, overlay tree or mesh topologies are typically constructed, such that peers utilize their available upload capacities to alleviate the excessive bandwidth demands on stream servers. Previous works rely on random selections of upstream peers, without optimizing the topologies towards maximized utilization of peer upload bandwidth, and as a result, minimized bandwidth costs on streaming servers. We propose Outreach, a distributed algorithm to construct overlay topologies among participating peers in streaming sessions. The design objective of Outreach is to optimize the quality of overlay topologies towards scalability, with respect to the number of participating peers in the session. To be scalable, Outreach seeks to maximize the utilization of available upload bandwidth on each participating peer, and consequently minimize the total bandwidth costs on streaming servers. With analysis, we show that Outreach constructs topologies such that peers can fully utilize their upload capacities, and present a practical distributed algorithm. With simulation-based comparison studies, we show that Outreach effectively achieves its goals in a high-churn peer-to-peer network with an assortment of peer uplink capacities and link delays     

A survey and comparison on overlay‐underlay mapping techniques in peer‐to‐peer overlay networks

Peer‐to‐peer (P2P) overlay networks were developed initially for file sharing such as Napster and Gnutella; but later, they have become popular for content sharing, media streaming, telephony applications, etc. Underlay‐unawareness in P2P systems can result in suboptimal peer selection for overlay routing and hence poor performance. In this paper, we present a comprehensive survey of the research work carried out to solve the overlay‐underlay mapping problems up till now. The majority of underlay‐aware proposals for peer selection focus on finding the shortest overlay routes by selecting nearest nodes according to proximity information. Another class of approaches is based on passive or active probing for provision of underlay information to P2P applications. Some other optimizations propose use of P2P middleware to extract, process, and refine underlay information and provide it to P2P overlay applications. Another class of approaches strive to use ISPs or third parties to provide underlay information to P2P overlay applications according to their requirements. We have made a state‐of‐the‐art review and comparison for addressing the overlay‐underlay mismatch in terms of their operation, merits, limitations, and future directions.     

Distributed upload bandwidth assigning algorithm in P2P VoD system

In a peer-to-peer(P2P) live streaming system,each peer uses greedy strategy to download chunks as many as possible so as to assure smooth playback and promote the chunk propagation.However,diversity of video playback rate,heterogeneity of peer downlink bandwidth and no prefetching limitation determine that greedy strategy is not the best strategy for P2P video-on-demand(VoD) system though this strategy performs well in P2P live system.To reasonably assign upload bandwidth among peers,we first present a stochastic model to relate expected downloading speed(EDS) with buffered data amount(BDA,the amount of data has been fetched in buffer,however has not been played yet by the peer),video playback rate and fluency(the probability of no interruption in a viewing process).On the base of this model,we design an equal fluency bandwidth assigning algorithm(EFBAA).In this algorithm,requesting peers compute EDS according to several local parameters(such as BDA,video playback rate and fluency) dynamically and independently and send the EDS to neighbor peers together with buffer map.Then the neighbor peer proportionally partitions and assigns its upload bandwidth to requesting peers according to their EDS.Extensive simulations demonstrate that EFBAA outperforms greedy strategy in terms of server load and startup latency.     

Push-to-Peer Video-on-Demand System: Design and Evaluation

We propose Push-to-Peer, a peer-to-peer system to cooperatively stream video. The main departure from previous work is that content is proactively pushed to peers, and persistently stored before the actual peer-to-peer transfers. The initial content placement increases content availability and improves the use of peer uplink bandwidth. Our specific contributions are: (i) content placement and associated pull policies that allow the optimal use of uplink bandwidth; (ii) performance analysis of such policies in controlled environments such as DSL networks under ISP control; (iii) a distributed load balancing strategy for selection of serving peers.     

Timely traffic identification on P2P streaming media

Since the year of 2006,peer-to-peer (P2P) streaming media service has been developing rapidly,the user scale and income scale achieve synchronous growth.However,while people enjoying the benefits of th...     

Network pricing: can both ISP and P2P benefit?

Internet service providers are facing increasing back pressure from rising access demand by users, especially peer‐to‐peer (P2P)‐based applications that greatly enhance the large‐scale distribution of content into and out of their networks. With the ever increasing consumption pressure on scarce bandwidth resources, ISPs have been forced to reconsider their business model of overselling ‘all‐you‐can‐eat’ broadband at flat rates. Technical solutions such as traffic differentiation or blocking violate the principle of network neutrality; traffic shaping and deep packet analysis fall short in the presence of encryption; and P4P (localized P2P)‐based solutions are difficult to achieve in a heterogeneous environment. Economically, various usage‐based pricing schemes have been proposed and discussed. While they can improve efficiency in bandwidth consumption, they tend to face strong customer resistance as users have strong preference in favour of simple flat rates. We argue that any feasible pricing reforms cannot deviate much from the current flat rates while providing financial incentives for bandwidth hogs to limit their bandwidth access. In contrast to normal usage‐based pricing models that charge by volume, we propose a temporal‐based pricing model that may generate a mutually beneficial solution that can not only increase the profitability of ISPs but also accommodate P2P, rather than killing it, without changing the software, protocols or hardware that clients or ISPs use on the network.Copyright © 2014 John Wiley & Sons, Ltd     

一种基于Tracker端偏向邻居选择的距离感知BitTorrent系统

To address cross-ISP traffic problem caused by BitTorrent, we present our design and evaluation of a proximity-aware BitTorrent system. In our approach, clients generate global proximityaware information by using landmark clustering; the tracker uses this proximity to maintain all peers in an orderly way and hands back a biased subset consisting of the peers who are physically closest to the requestor. Our approach requires no co-operation between P2P users and their Internet infra structures, such as ISPs or CDNs, no constantly path monitoring or probing their neighbors. The simulation results show that our approach can not only reduce unnecessary cross- ISP traffic, but also allow downloadsing fast.     

P2broadcast: a hierarchical clustering live video streaming system for P2P networks

This work describes a novel live video streaming system for P2P networks, referred to as P2broadcast. The video streaming service has bandwidth requirements to guarantee presentation quality. Therefore, a scalable strategy to quickly find a path from a media server to a client with abundant bandwidth is very important. A common approach in the literature is the bandwidth first (BF) scheme, which allows a newcomer to adopt a BF tree traversal scheme to find its parent peer on the P2P overlay tree to retrieve the media content. The BF scheme is likely to build a deep overlay tree, resulting in long start‐up latency as the number of peers on the overlay tree grows. P2broadcast reduces start‐up latency by organizing peers into hierarchical clusters and making the overlay tree become a ‘short‐and‐wide’ tree. The hierarchical clustering structure enables a newcomer to find its parent peer among the set of peers that are more likely to provide large available bandwidth only. Limiting the set of potential parent peers not only reduces start‐up latency but also improves the system availability. Additionally, unlike the BF scheme that only concerns available bandwidth, P2broadcast utilizes a cost function to evaluate the appropriateness of a potential parent peer. The cost function considers the depth of the newcomer on the overlay tree, making the overlay tree become a short‐and‐wide tree. In addition to start‐up latency reduction, the short‐and‐wide tree feature also alleviates the service interruption probability due to the leaving or failure of a peer. Our simulation results show that P2broadcast greatly outperforms the BF scheme in terms of system availability, and achieves around 66% savings in start‐up latency and 10% decrement in service interruption probability. Copyright © 2005 John Wiley & Sons, Ltd.     

Robust mobile video streaming in a peer-to-peer system

In a peer-to-peer (P2P) video streaming system, peers not only consume video, but also route it to other peers in the system, where ordinary peers are assumed to have sufficient downlink speed and media capability. This assumption often fails when the P2P system consists of peers that are heterogeneous in their computing power, hardware, and media capability.In this paper, we address a problem of streaming video to mobile devices, which are less capable than ordinary peers. In order to stream video to mobile devices, transcoding is often required to render video suitable for their small display, limited downlink speed, and limited video decoding capability. However, performing transcoding at a single peer is vulnerable to peer churn, which leads to video disruption. We propose interleaved distributed transcoding (IDT), a robust video encoding scheme that allows peers more capable than mobile devices to perform transcoding in a collaborative fashion. IDT is designed in such a way that transcoded substreams are assembled into a single video stream, which can be decoded by any H.264/AVC baseline profile compliant decoder. Extensive simulations and its implementation in a real P2P system demonstrate that the proposed scheme not only reduces computational load at a peer, but also achieves robust streaming in the case of peer failure or packet loss due to adverse wireless channel conditions. We confirm this finding by analyzing the effect of distributed transcoding under peer failure.     

3DTV over IP

In this paper, technologies for distribution of a variety of three-dimensional (3-D) video and 3-D TV services over IP networks are described. The approaches for encoding stereoscopic and MW have been standardized in the form of MPEG "video-plus-depth" and the JVT MVC standards. It has been shown that both approaches can encode stereoscopic video at about 1.2 times the bit rate of monoscopic video (when using unequal inter-view bit allocation in the case of MVC). Also this kind of interactive system increases the bandwidth requirement significantly. A multitude of strategies have been considered for streaming such encoded MW using RTP/UDP/IP or RTP/DCCP/IP. Video streaming architectures can be classified as 1) server unicasting to one or more clients, 2) server multicasting to several clients, 3) P2P unicast distribution, where each peer forwards packets to another peer, and 4) P2P multicasting, where each peer forwards packets to several other peers.     

Study of the relationship between peer-to-peer systems and IP multicasting

Peer-to-peer (P2P) systems, which have attracted public attention, involve a number of directly connected "peers" exchanging various types of information among themselves. However, applications based on P2P systems generally generate a lot of traffic and require not only the resources of every peer (e.g., CPU, memory, and bandwidth) but also many network resources. We think the main problems of P2P systems can be solved using IP multicasting, which is becoming popular as an effective way to transfer streaming media over the network and can reduce network traffic and the load on a streaming server. We propose applying IP multicasting to P2P systems. After mentioning that almost every application can be improved by our proposal, we discuss which routing protocol is suitable. Finally, we show that we can get good results even when part of the network does not support IP multicasting.     

P2P流媒体技术原理及应用

基于P2P的流媒体技术是一项非常有前途的技术,该技术有两方面的优点:不需要互联网路由器和网络基础设施的支持,因此性价比高且易于部署;流媒体用户不只是下载媒体流,而且还把媒体流上载给其他用户,因此,这种方法可以扩大用户组的规模,且由更多的需求带来更多的资源。由于P2P流媒体系统中节点存在不稳定性,因此P2P流媒体系统需要在文件定位技术、节点选择技术、容错以及安全机制方面有所突破。此外在如何管理节点并建立发布树、如何应付不可预知的节点失效、如何适应网络状态变化方面也面临着一些挑战。     

P2P业务流量特性及其对Web业务的影响

近年来各种P2P应用不断出现及演进,P2P应用正逐渐成为下一代互联网的杀手级应用。但同时P2P消耗了Internet的大部分带宽,造成了网络技术服务商(ISP)接入网络的拥塞,从而使传统Internet应用性能受到严重影响。从P2P流数量、服务器负载、网络瓶颈点分布、往返时间(RTT)的异构特性等方面可以看出,P2P流量消耗了巨大的网络带宽,影响了传统Internet业务的性能,增加了运营成本。利用P2P流量和Web流量的集成模型,可以量化分析P2P流对Web流的影响,使网络运营商可以在网络瓶颈点对P2P连接数进行优化和调整,从而有效地控制P2P流量。NS2仿真结果较好地验证了该模型的有效性。     

Modeling and application of moderate prefetching strategy based on video slicing for P2P VoD systems

In peer-to-peer (P2P) video-on-demand (VoD) streaming systems,each peer contributes a fixed amount of hard disk storage (usually 2 GB) to store viewed videos and then uploads them to other requesting p...     

一种P2P直播系统调度管理方法的设计与实现

P2P网络是自由的网络,在P2P网络中,每个节点（Peer）都是对等的,可以进行信息和服务的自由交换。由于节点具有随机性,采用P2P技术实现流媒体的直播系统时,必须合理地对终端用户节点进行调度管理。针对这一问题,论文设计了一种P2P直播系统的调度管理方法,很好地解决了终端用户节点的调度管理问题,能使用户获取可靠性高、质量好的流媒体服务,对流媒体技术的发展具有一定的指导意义。     

SDHT:面向P2P直播系统的高效单跳分布式哈希查找策略

Video data location plays a key role for Peer-to-Peer (P2P) live streaming applications. In this paper, we propose a new one-hop Distributed Hash Table (DHT) lookup framework called Streaming-DHT (SDHT) to provide efficient video data location service. By adopting an enhanced events dissemination mechanism-EDRA+ , the accuracy of routing table at peers can be guaranteed. More importantly, in order to enhance the performance of video data lookup operation without incurring extra overhead, we design a so-called Distributed Index Mapping and Management Mechanism (DIMM) for SDHT. Both analytical modeling and intensive simulation experiments are conducted to demonstrate the effectiveness of SDHT framework. Numerical results show that almost 90% requested video data can be retrieved within one second in SDHT based systems, and SDHT needs only 26% average bandwidth consumption when compared with similar one-hop DHT solutions such as D1HT. This indicates that SDHT framework is an appropriate data lookup solution for time-sensitive network applications such as P2P live streaming.     

Enhanced centralized management of gateways using redirection-based rules sharing for mobile network virtualization

One of the current issues in the peer-to-peer streaming systems is to supply sufficient upload bandwidth for continuous streaming of high-quality video channels. The helpers as upload bandwidth boosters can improve the streaming capacity of system, so that the imbalance of upload bandwidth between different video channel overlays is compensated. With the deployment of helpers as an intermediate level between server and peers, building and maintaining the optimal peer-helper topology becomes a challenging task since the one-directional nature of video streaming from the helpers to users makes the well-known reciprocity-based algorithms useless. Because of selfish behavior of peers and lack of a central authority among them, selection of helpers requires implicit coordination. In this paper, we design a decentralized, stochastic approximation helper selection mechanism which is adaptable to supply and demand pattern of various video channels. Our regret-tracking-based solution for allowing peers to strategically exploit their shared resources is guaranteed to converge to the correlated equilibria (CE) among the helper selection strategies. Online convergence to the set of CE is achieved through the regret-tracking algorithm which tracks the equilibrium in the presence of stochastic dynamics of helpers’ bandwidth. The resulting CE can help to select proper cooperation policies. Simulation results demonstrate that our algorithm achieves good convergence, load distribution on helpers and sustainable streaming rates for peers.