P2P traffic optimization

Peer-to-peer (P2P) based content distribution systems have emerged as the main form for content distribution on the Internet,which can greatly reduce the distribution cost of content providers and improve the overall system scalability.However,the mismatch between the overlay and underlay networks causes large volume of redundant traffic,which intensifies the tension between P2P content providers and ISPs.Therefore,how to efficiently use network resources to reduce the traffic burden on the ISPs is crucial for the sustainable development of P2P systems.This paper surveys the state-of-art P2P traffic optimization technologies from three perspectives:P2P cache,locality-awareness and data scheduling.Technological details,comparison between these technologies and their applicabilities are presented,followed by a discussion of the issues that remain to be addressed and the direction of future content distribution research.     

一种P2P和ISPs协作的P2P节点选择机制

引入ISP跳数(IH)来衡量在自治系统(AS:Autonom ous System)拓扑中位于不同位置的AS跳数的开销,并引入了骨干链接开销(CBC)来衡量P2P应用通过的骨干网络数量.借助于IH和CBC两个参数分析了P2P应用对ISPs流量的影响.并且在此基础上设计一个新的机制,命名为ISP-DDHA.在ISP-DDHA中,针对主要参数设计了相应的路由选择算法,用来改进ISPs和P2P系统性能.实验结果表明:在某些P2P流量负载较大的网络场景中,相比[7],ISP-DDHA可以减少约7.4%的DAH开销、12.1%的IH开销和10.4%的CBC开销.     

Characterization of community based-P2P systems and implications for traffic localization

In this paper, we present one of the first and most extensive characterizations of closed community-based P2P systems. Such systems are organic groups of peer-to-peer (P2P) clients, which can be joined only by users belonging to a certain network (e.g., connected to a given Internet Service Provider (ISP)). A number of factors motivate the growth of these communities, such as quality of content, anonymity of transfers, and the potential for better performance that enhances user experience. Our study is conducted in two contrasting environments—a campus network and a national ISP—located in different continents. In both cases, large-scale closed communities have been found to be the predominant P2P systems in use. We shed light both on the factors motivating the growth of such communities, and present results characterizing the extensiveness of their usage, the performance achievable by the systems, and the implications of such communities for network providers. While our findings are interesting in their own right, they also offer important lessons for ongoing research that seeks to localize traffic within ISP boundaries. In particular, our results suggest that (i) in ISPs with heterogeneous access technologies, the performance benefits to users on localizing P2P traffic is largely dependent on the degree of seed-like behavior of peers behind high-bandwidth access technologies; and (ii) while localization can reduce the traffic on Internet peering links, it has the potential to cause a significant increase in traffic on internal links of providers, potentially requiring upgrades of network links.     

P2P流量优化

基于peer-to-peer(P2P)技术的内容分发系统已成为互联网内容分发的重要形式,它能大幅减轻P2P内容提供商的分发代价,提高系统的可扩展性.但是,覆盖网络和底层网络的失配导致了网络资源的浪费,产生了大量的冗余流量,激化了P2P内容提供商和网络运营商(ISP)之间的矛盾.因此,如何有效利用底层网络的带宽资源,降低P2P内容分发系统对ISP网络的流量压力,是P2P系统得以良性和可持续发展的关键.本文综述了P2P内容分发系统流量优化的相关技术研究现状.从P2Pcache、位置感知技术和数据调度算法3个维度出发详细阐述了不同的技术在P2P流量优化中的作用,对各种技术进行了详细的综述和对比分析,探讨了各种技术的适用环境,指出了存在的问题和未来内容分发的发展方向.     

一种基于BT 的域间P2P 流量优化方法

随着P2P软件的普及,P2P成为影响Internet网络结构的关键应用．在中国运营商的长途骨干网上,P2P流量占一半以上,不仅给ISP带来了巨大的压力,也使网络拥塞现象日益严重．据此本文以P2P常用协议BT为对象提出一种优化方案,通过用户协作与估算模拟底层网络相综合的方法,在不影响性能下,引导流量更多地在本地网络上发生,降低域间及主干网络上的P2P流量．测试表明,该机制不仅能尽量将域间流量本地化达到整体优化的目的。而且更能增强用户系统的性能．     

A game–theoretic analysis of the implications of overlay network traffic on ISP peering

Inter-ISP traffic flow determines the settlement between ISPs and affects the perceived performance of ISP services. In today’s Internet, the inter-ISP traffic flow patterns are controlled not only by ISPs’ policy-based routing configuration and traffic engineering, but also by application layer routing. The goal of this paper is to study the economic implications of this shift in Internet traffic control assuming rational ISPs and subscribers. For this purpose, we build a general traffic model that predicts traffic patterns based on subscriber distribution and abstract traffic controls such as caching functions and performance sensitivity functions. We also build a game–theoretic model of subscribers picking ISPs, and ISPs making provisioning and peering decisions. In particular, we apply this to a local market where two ISPs compete for market share of subscribers under two traffic patterns: “Web” and “P2P overlay”, that typifies the transition the current Internet is going through. Our methodology can be used to quantitatively demonstrate that (1) while economy of scale is the predominant property of the competitive ISP market, P2P traffic may introduce unfair distribution of peering benefit (i.e. free-riding); (2) the large ISP can restore more fairness by reducing its private capacity (bandwidth throttling), which has the drawback of hurting business growth; and (3) ISPs can reduce the level of peering (e.g. by reducing peering bandwidth) to restore more fairness, but this has the side-effect of also reducing the ISPs’ collective bargaining power towards subscribers.     

An ISP-friendly inter-overlay coordination framework for multiple coexisting P2P systems

As Peer-to-Peer (P2P) systems are widely deployed in the Internet, P2P traffic control becomes a challenge for Internet Service Providers (ISPs) and P2P system vendors. Some recent works consider the interaction between ISPs and P2P systems, and propose ISP-friendly P2P traffic control mechanisms for reducing cross-ISP P2P traffic. In this paper, we consider another fundamental problem: the performance optimization and the interaction among multiple coexisting P2P systems. Specifically, we propose an ISP-friendly inter-overlay coordination framework (COOD) for controlling P2P traffic. The COOD framework consists of three important components: network traffic optimization, P2P service differentiation, and ISP policy enforcement. Our packet-level simulation results show that, compared with current P2P traffic control mechanisms, the COOD framework can provide better overall performance to multiple coexisting P2P systems, achieve service differentiation, and implement flexible mechanisms to effectively control cross-ISP P2P traffic.     

A game-theoretic evaluation of an ISP business model in caching

Internet traffic volume is increasing and this causes scalability issues in content delivery. This problem can be addressed with different types of caching solutions. The incentives of different stakeholders to pay for these solutions are not known. However, it has been identified that Internet service providers (ISPs) need to be involved in the process of cache deployment due to their ownership of the network. This work evaluates a new business model where ISPs charge content providers (CPs) for a caching service because CPs benefit from more efficient content distribution. We provide conditions for sustainable paid in-network caching and their numerical evaluation in order to aid strategic decision-making by CPs, ISPs, and Cloud storage providers (CSPs). Although ISP caching as a paid service may not be an equilibrium, it turns out to be Pareto optimal at the right pricing. This encourages cooperation between CPs and ISPs. CSPs may choose cache friendly physical locations for their facilities in order to provide the necessary capacity to the ISPs. However, the required amounts are in all likelihood too small to be an incentive for the CSPs. ISP caching as a paid service can be an equilibrium when future benefits are considered and when the ISPs terminate caching-related improvements of service quality for clients who do not pay for caching.     

基于网络测量的P2P跨域流量优化机制

P2P技术的普及优化了用户的体验,但对带宽的过度消耗也带给网络运营商巨大的压力。据此提出基于网络测量的、业务相关P2P跨域流量优化机制,该机制对底层网络建立模型,通过综合考量底层的网络信息和具体P2P业务的特殊性来优化节点互联。实验结果表明,该处理机制明显减少了跨域流量,优化了P2P用户的体验。     

P4P:P2P产业可持续发展的必经之路

近年来互联网上P2P应用业务得到了飞速的发展,同时占用了大量的带宽资源造成了带宽吞噬。至此,点对点网络数据传输新体系P4P技术应运而生,能有效减少网络骨干线路的负载和提高ISP的网络效率。本文从P2P的发展困境引入,分析P4P技术原理并比较P2P与P4P的性能。     

P2P节点智能选择机制的研究与实现

对对等网络（P2P）的流量问题进行了分析,指出P2P流量问题产生的原因。融合网络运营商、地理位置等信息,提出了一种节点智能选择机制。该机制优先选择属于相同运营商和地理位置接近的节点作为数据交换对象,最大限度地将数据流量控制在本地网络和同一运营商的网络中,从而减少骨干网和网络出口的负载,同时提高了数据传输性能。在Bit Torrent (BT)系统中融合智能选择机制后,Tracker智能选择的节点在往返时延、路由跳数上均得到优化,实验数据表明该机制能有效减少“流量旅行”,提高P2P传输效率。     

BufferBank: A distributed cache infrastructure for peer-to-peer application

Peer-to-peer (P2P) systems generate a major fraction of the current Internet traffic which significantly increase the load on ISP networks. To mitigate these negative impacts, many previous works in the literature have proposed caching of P2P traffic. But very few have considered designing a distributed caching infrastructure in the edge network. This paper demonstrates that a distributed caching infrastructure is more suitable than traditional proxy cache servers which cache data in disk, and it is viable to use the memory of users in the edge network as the cache space. This paper presents the design and evaluation of a distributed network cache infrastructure for P2P application, called BufferBank. BufferBank provides a number of application interfaces for P2P applications to make full use of the cache space. Three-level mapping is introduced and elaborated to improve the reliability and security of this distributed cache mechanism. Our measurement results suggest that BufferBank can decrease the data obtaining delay, compared with traditional P2P cache server based on disk.     

A Measurement Study of a Large-Scale P2P IPTV System

An emerging Internet application, IPTV, has the potential to flood Internet access and backbone ISPs with massive amounts of new traffic. Although many architectures are possible for IPTV video distribution, several mesh-pull P2P architectures have been successfully deployed on the Internet. In order to gain insights into mesh-pull 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 mesh-pull PPLive system. We have also collected extensive packet traces for various different measurement scenarios, including both campus access networks and residential access networks. The measurement results obtained through these platforms bring important insights into P2P IPTV systems. Specifically, our results show the following. 1) P2P IPTV users have the similar viewing behaviors as regular TV users. 2) During its session, a peer exchanges video data dynamically with a large number of peers. 3) A small set of super peers act as video proxy and contribute significantly to video data uploading. 4) Users in the measured P2P IPTV system still suffer from long start-up delays and playback lags, ranging from several seconds to a couple of minutes. Insights obtained in this study will be valuable for the development and deployment of future P2P IPTV systems.     

Software-Defined Multicast for Over-the-Top and Overlay-based Live Streaming in ISP Networks

The increasing amount of over-the-top (OTT) live streams and the lack of global network layer multicast support poses challenges for a scalable and efficient streaming over the Internet. Content Delivery Networks (CDNs) help by delivering the streams to the edge of almost every Internet Service Provider (ISP) network of the world but usually also end there. From there on, the streams are to be delivered to the clients using IP unicast, although an IP multicast functionality would be desirable to reduce the load on CDN nodes, transit links, and the ISP infrastructure. IP multicast is usually not available due to missing control and management features of the protocol. Alternatively, Peer-to-Peer (P2P) mechanisms can be applied to extend the overlay multicast functionality of the CDN towards the clients. Unfortunately, P2P only improves the situation for the CDN but makes it more challenging for the ISP as even more unicast flows are generated between clients inside and outside the ISP network. To tackle this problem, a Software-Defined Networking-based cross-layer approach, called Software-Defined Multicast (SDM), is proposed in this paper, enabling ISPs to offer network layer multicast support for OTT and overlay-based live streaming as a service. SDM is specifically tailored towards the needs of P2P-based video stream delivery originating from outside the ISP network and can easily be integrated with existing streaming systems. Prototypical evaluations show significantly improved network layer transmission efficiencies when compared to other overlay streaming mechanisms, down to a level as low as for IP multicast, at linearly bounded costs.     

基于周期性无线网络数据传输的缓存管理技术研究

网络缓存管理是一种降低Internet流量和提高终端用户响应时间的网络技术。它来自于计算机和网络的其他领域,如目前流行的Intel架构的CPU中就存在缓存,用于提高内存存取的速度;各种操作系统在进行磁盘存取时也会利用缓存来提高速度;分布式文件系统通常也通过缓存来提高客户机和服务器之间的速度。无线网络数据的缓存可以在客户端,也可以在网络上,该文基于此,对周期性网络数据传输过程中的缓存管理技术进行了初步研究。     

File-aware P2P traffic classification: An aid to network management

As P2P dominates Internet traffic in recent years, ISPs are striving to balance between providing the basic networking services for P2P users and properly managing network bandwidth usage. That is, ISPs are required to provide proper bandwidth for each P2P user to get every file to fulfill their provision for communications, while they have to control bandwidth consumption for efficient usage. However, current P2P traffic management strategies are unable to satisfy both requirements. In this paper, our goal is to design a simple and effective scheme for ISPs to moderate the tradeoff. It is achieved by proposing a file-aware P2P traffic classification method that can identify files and the associated flows. The file-level information can lead to more efficient and flexible management strategies on a per-file basis. We offer two alternatives: constraining the per-file bandwidth consumption and the number of per-file concurrent flows. Finally, a real-life trace is measured using our file-aware method from the perspectives of peers and files. The results indicate that ISPs can gain enough opportunities to flexibly choose proper traffic manage parameters according to actual demands.     

Interaction of ISPs: Distributed Resource Allocation and Revenue Maximization

The Internet is a hierarchical architecture comprising heterogeneous entities of privately owned infrastructures, where higher level Internet service providers (ISPs) supply connectivity to the local ISPs and charge the local ISPs for the transit services. One of the challenging problems facing service providers today is how the profitability can be increased while maintaining good service qualities as the network scales up. In this work, we seek to understand the fundamental issues on the "interplay" (or interaction) between ISPs at different tiers. Although the local ISPs (which we term peers) can communicate with each other by purchasing the connectivity from transit ISPs, there stands an opportunity for them to set up private peering relationships. Under this competitive framework, we explore the issues on 1) the impact of peering relationship; 2) resource distribution; 3) revenue maximization; and 4) condition for network upgrade. First, a generalized model is presented to characterize the behaviors of peers and the transit ISP, in which their economic interests are reflected. We study how a peer can distributively determine its optimal peering strategy. Furthermore, we show how a transit ISP is able to utilize the available information to infer its optimal pricing strategy, under which a revenue maximization is achieved. Two distributed algorithms are proposed to help ISPs to provide a fair and efficient bandwidth allocation to peers, avoiding a resource monopolization of the market. Last, we investigate the above issues in a "many-peers region," that is, when we scale up the network. We provide insightful evidence to show that the ISPs can still gain profits as they upgrade the network infrastructures. Extensive simulations are carried out to support our theoretical claims.     

A novel cooperative caching algorithm for massive P2P caches

For an ISP (Internet Service Provider) that has deployed P2P caches in more than one ASs (autonomous systems), cooperative caching which makes their caches cooperate with each other can save more cost of carrying P2P traffic than independent caching. However, existing cooperative caching algorithms only use objects’ popularity as the measurement to decide which objects should be cached, and cost on intra-ISP links that has great impact on the benefits of cooperative caching is not considered. In this paper, we first model the cooperative caching problem as a NP-Complete problem, which is based on our analysis about the cost of serving requests with consideration of both the objects’ popularity and the cost on intra-ISP links. Then we propose a novel cooperative caching algorithm named cLGV (Cooperative, Lowest Global Value). The cLGV algorithm uses a new concept global value to estimate the benefits of caching or replacing an object in the cooperative caching system, and the global value of each object is evaluated according to not only objects’ popularity in each AS but also cost on intra-ISP links among ASs. Results of both synthetic and real traces driven simulations indicate that our cLGV algorithm can save the cost of carrying P2P traffic at least 23 % higher than that of existing cooperative caching algorithms.     

Distributed caching in unstructured peer-to-peer file sharing networks

Nowadays, the peer-to-peer (P2P) system is one of the largest Internet bandwidth consumers. To relieve the burden on Internet backbone and improve the query and retrieve performance of P2P file sharing networks, efficient P2P caching algorithms are of great importance. In this paper, we propose a distributed topology-aware unstructured P2P file caching infrastructure and design novel placement and replacement algorithms to achieve optimal performance. In our system, for each file, an adequate number of copies are generated and disseminated at topologically distant locations. Unlike general believes, our caching decisions are in favor of less popular files. Combined with the underlying topology-aware infrastructure, our strategy retains excellent performance for popular objects while greatly improves the caching performance for less popular files. Overall, our solution can reduce P2P traffic on Internet backbone, and relieve the over-caching problem that has not been properly addressed in unstructured P2P networks. We carry out simulation experiments to compare our approaches with several traditional caching strategies. The results show that our algorithms can achieve better query hit rates, smaller query delay, higher cache hit rates, and lower communication overhead.     

Layer 2 over IP/MPLS

Over the past several years, traditional carriers and Internet service providers (ISPs) have invested billions of dollars deploying high-speed, high-capacity IP networks. This expansion is intended to lay the foundation for a network that could accommodate exponential traffic growth and deliver new revenue-generating services. Traffic from advanced services incorporating elements such as on-demand video, packet voice, wireless communications, and peer-to-peer networking is expected to consume whatever capacity providers can offer while leading to increased opportunities for revenue growth. The advanced services traffic has yet to materialize. An unintentional consequence of this buildout, however, is that ISP networks possess a glut of capacity. At the same time, ISPs are under great pressure to reduce operational and infrastructure costs while attempting to make money and attract customers with new services. One way to achieve both goals is to carry all traffic over a single IP or multiprotocol label-switching (MPLS) network