UARA in edge routers: an effective approach to user fairness and traffic shaping

The ever‐increasing share of the peer‐to‐peer (P2P) traffic flowing in the Internet has unleashed new challenges to the quality of service provisioning. Striving to accommodate the rise of P2P traffic or to curb its growth has led to many schemes being proposed: P2P caches, P2P filters, ALTO mechanisms and re‐ECN. In this paper, we propose a scheme named ‘UARA:textbfUser/ A pplication‐aware R ED‐based A QM’ which has a better perspective on the problem: UARA is proposed to be implemented at the edge routers providing real‐time near‐end‐user traffic shaping and congestion avoidance. UARA closes the loopholes exploited by the P2P traffic by bringing under control the P2P users who open and use numerous simultaneous connections. In congestion times, UARA monitors the flows of each user and caps the bandwidth used by ‘power users’ which leads to the fair usage of network resources. While doing so, UARA also prioritizes the real‐time traffic of each user, further enhancing the average user quality of experience (QoE). UARA hence centralizes three important functionalities at the edge routers: (1) congestion avoidance; (2) providing user fairness; (3) prioritizing real‐time traffic. The simulation results indicate that average user QoE is significantly improved in congestion times with UARA at the edge routers. Copyright © 2011 John Wiley & Sons, Ltd.     

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     

Extending P2PMesh: topology‐aware schemes for efficient peer‐to‐peer data sharing in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that provides low‐cost broadband access to the Internet for fixed and mobile wireless end users. An orthogonal evolution in computer networking has been the rise of peer‐to‐peer (P2P) applications such as P2P data sharing. It is of interest to enable effective P2P data sharing in this type of networks. Conventional P2P data sharing systems are not cognizant of the underlying network topology and therefore suffer from inefficiency. We argue for dual‐layer mesh network architecture with support from wireless mesh routers for P2P applications. The main contribution of this paper is P2PMesh: a topology‐aware system that provides combined architecture and efficient schemes for enabling efficient P2P data sharing in WMNs. The P2PMesh architecture utilizes three schemes: (i) an efficient content lookup that mitigates traffic load imbalance at mesh routers; (ii) an efficient establishment of download paths; and (iii) a data transfer protocol for multi‐hop wireless networks with limited capacity. We note here that the path establishment and data transfer schemes are specific to P2P traffic and that other traffic would use routes determined by the default routing protocol in the WMN. Simulation results suggest that P2PMesh has the potential to improve the performance of P2P applications in a wireless multi‐hop setting; specifically, we focused on data sharing, but other P2P applications can also be supported by this approach. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

Slack time–based scheduling scheme for live video streaming in P2P network

Nowadays, peer‐to‐peer network plays a significant role in data transfer and communication. The past few years have witnessed considerable growth in this area because of its inherent advantages. Peer‐to‐peer live streaming has a significant impact on video transmission over the Internet. Major factors that influence the performance of P2P live streaming are overlay construction and scheduling strategies. Although, a large number of scheduling schemes are developed but none of them is comprehensive enough to provide solutions to live streaming issues. These suffer from substantial delay and low video quality at the receiver side. In this paper, a new start‐up–based selection procedure and slack time–based scheduling scheme is proposed. The start‐up selection procedure defines the start‐up buffer location for new peer, and the scheduling scheme selects both the chunk and peers. The proposed scheduling scheme uses both push and pull priority–based strategies. The simulation results of the proposed approach demonstrates significant improvement in both the network performance and video quality at the receiver side. It is observed that playback delay, startup delay, and end‐to‐end delay in the network are reduced and quality of the video at receiver side is improved as the distortion and frame loss ratio is decreased.     

Efficient complementary caching for ISP-aware networks

Internet service providers(ISPs) have taken some measures to reduce intolerable inter-ISP peer-to-peer(P2P) traffic costs,therefore user experiences of various P2P applications have been affected.The recently emerging offline downloading service seeks to improve user experience by using dedicate servers to cache requested files and provide high-speed uploading.However,with rapid increase in user population,the server-side bandwidth resource of offline downloading system is expected to be insufficient in the near future.We propose a novel complementary caching scheme with the goal of mitigating inter-ISP traffic,alleviating the load on servers of Internet applications and enhancing user experience.Both architecture and caching algorithm are presented in this paper.On the one hand,with full knowledge of P2P file sharing system and offline downloading service,the infrastructure of complementary caching is designed to conveniently be deployed and work together with existing platforms.The co-operational mechanisms among different major components are also included.On the other hand,with in-depth understanding of traffic characteristics that are relevant to caching,we develop complementary caching algorithm with respect to the density of requests,the redundancy of file and file size.Since such relevant information can be real-time captured in our design,the proposed policy can be implemented to guide the storage and replacement of caching unities.Based on real-world traces over 3 months,we demonstrate that the complementary caching scheme is capable to achieve the ’three-win’ objective.That is,for P2P downloading,over 50% of traffic is redirected to cache;for offline downloading,the average server-dependence of tasks drops from 0.71 to 0.32;for user experience,the average P2P transfer rate is increased by more than 50 KB/s.     

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。     

Sustained service lookup in areas of sudden dense population

As mobility became the norm rather than the exception, location‐based services are playing more of a key role in assisting mobile users. In this paper, we address the challenges of providing location‐based services to users in areas of sudden population increases, such as stadiums and traffic jams. A sudden increase in the number of mobile users leads to an increasing demand for the already scarce wireless bandwidth, thus causing dramatical throughput degradation and an increase in connectivity failures. We propose a hybrid model within which a peer‐to‐peer mode is deployed to assist the cellular‐based network whenever a sudden increase in population density is sensed by the base station. Location‐based data is migrated to selected elite nodes, thus allowing other peer nodes to get their information locally. This approach is proven, through experimental results, to decrease the query response time and number of query failures. Copyright © 2006 John Wiley & Sons, Ltd.     

P2P network traffic control mechanism based on global evaluation values

Peer-to-peer (P2P) computing technology has been widely used on the Internet to exchange data. However, it occupies much network bandwidth, and thus greatly influences traditional business on the Interact. Besides, problems about free-riders and 'tragedy of the commons' in the P2P environment estrange from it P2P users who constantly contribute to the network with quality resources. This article proposes a new P2P network traffic control mechanism based on global evaluation values. It aims to help individual users to avoid peak traffic time as much as possible, ease network congestion and protect traditional business on the Interact, as well as differentiating priority grades of peers according to their contributions and stimulating them to share their valuable resources actively. This article first analyzes the current state of network traffic, and then elaborates on P2P network traffic control policies and proposes the peer's priority level differentiation mechanism based on global evaluation values. Finally,after the testing results and analysis of the proposed P2P network traffic control mechanism are discussed, conclusions are drawn.     

SeekStream: adapting to dynamic user behavior in P2P video‐on‐demand

In recent years, the users' perceived quality of experience (QoE) in streaming services has gained a lot of attention. Particularly, a number of research efforts have focused on providing live streaming and video‐on‐demand (VoD) services using peer‐to‐peer (P2P) architectures. However, in these proposed architectures, the heterogeneity of users and their dynamic behavior has not been sufficiently studied. In a real life scenario, where users have highly heterogeneous bandwidth resources (cable, DSL, 3G networks, etc) and can arbitrarily decide to perform a VCR function (stop, fast forward and seeking), ignoring this behavior can significantly deteriorate the system's efficiency and the perceived QoE. In this paper, we present SeekStream, a scalable P2P VoD architecture that ensures the stable delivery of the video stream to every participating user even in cases of high heterogeneity and frequent seeking operations. Specifically, SeekStream is a set of algorithms that optimize the P2P overlay dynamically and in a distributed fashion, making it adaptive to users dynamic behavior and bandwidth changes. The available bandwidth resources of the participating users are optimally exploited, keeping the contribution from the media server(s) to a minimal level. To illustrate the performance of the proposed algorithms, we are using a centralized overlay network manager that discovers the optimal network graph as a reference. We have developed an extensive P2P VoD simulator that shows the efficiency, scalability, and stability of our system under variant and dynamic conditions. The algorithms of our proposed system introduce less than 4% bandwidth overhead while we achieve high offloading of the media server(s). SeekStream guarantees a high block reception rate for the users, even under extreme seeking patterns. Copyright © 2016 John Wiley & Sons, Ltd.     

Replication schemes for peer‐to‐peer content in wireless mesh networks with infrastructure support

Many mobile devices (e.g., smart phones, PDAs, portable computers) and wireless routers (e.g., WiFi access points) nowadays are equipped with ad hoc transmission mode. In a dense environment such as a college/office campus, this creates the possibility of forming a wireless mesh network (WMN) in which mobile users communicate with each other through multiple wireless hops. This allows mobile users to exchange (share) files over the free access WMN rather than a carrier frequency such as 3G and WiMax. We consider a peer‐to‐peer (P2P) content sharing setting in a WMN, wherein the mesh network operator over‐provision a number of mesh routers in the network with additional storage capacity and P2P‐aware devices that are programmed to cache and store P2P content. Those mesh routers act as caches and participants in P2P content sharing. The aim of this setting is to both reduce the cost of communications between peers within the WMN (i.e., reduce bandwidth and energy that P2P traffic consumes in the network), and enhance the performance of P2P content sharing (i.e., reduce the average P2P content download delay). Our main contribution in this paper is an optimum P2P content replication strategy at the participating mesh routers. In particular, we determine the optimum number of replicas for every P2P file such that the average access cost of all files in the network is minimized. We propose a centralized algorithm that enables the participating mesh routers to implement the optimal strategy. We further propose a distributed (low cost) algorithm for P2P content replication at the participating mesh routers, and show that the distributed algorithm mimics the optimal strategy very well. The analytical and simulation results show that our replication strategy significantly reduces the average overall cost of accessing P2P files in the WMN as compared with other commonly used replication strategies. Copyright © 2013 John Wiley & Sons, Ltd.     

Adaptive traffic sampling for P2P botnet detection

Peer‐to‐peer (P2P) botnets have become one of the major threats to network security. Most existing botnet detection systems detect bots by examining network traffic. Unfortunately, the traffic volumes typical of current high‐speed Internet Service Provider and enterprise networks are challenging for these network‐based systems, which perform computationally complex analyses. In this paper, we propose an adaptive traffic sampling system that aims to effectively reduce the volume of traffic that P2P botnet detectors need to process while not degrading their detection accuracy. Our system first identifies a small number of potential P2P bots in high‐speed networks as soon as possible, and then samples as many botnet‐related packets as possible with a predefined target sampling rate. The sampled traffic then can be delivered to fine‐grained detectors for further in‐depth analysis. We evaluate our system using traffic datasets of real‐world and popular P2P botnets. The experiments demonstrate that our system can identify potential P2P bots quickly and accurately with few false positives and greatly increase the proportion of botnet‐related packets in the sampled packets while maintain the high detection accuracy of the fine‐grained detectors.     

一种基于区域缓存的BitTorrent流量控制机制

以BitTorrent为代表的P2P应用流量已占据电信运营商网络流量的60%以上,由于BitTorrent客户端主要依据上传速度来选择传输节点,并不能检测到同一区域网络中存在具有相同数据的客户端,导致经常出现通过网间路由器的重复流量,降低了带宽的使用效率。提出通过设置透明的代理tracker服务器和设立分布式的peer缓存管理系统,使得将BitTorrent流量尽量控制在区域网络范围内,减少通过骨干路由的流量,同时使得BitTorrent客户端也能得到更快速的下载。     

An optimal bandwidth allocation and data droppage scheme for differentiated services in a wireless network

This paper presents an optimal proportional bandwidth allocation and data droppage scheme to provide differentiated services (DiffServ) for downlink pre‐orchestrated multimedia data in a single‐hop wireless network. The proposed resource allocation scheme finds the optimal bandwidth allocation and data drop rates under minimum quality‐of‐service (QoS) constraints. It combines the desirable attributes of relative DiffServ and absolute DiffServ approaches. In contrast to relative DiffServ approach, the proposed scheme guarantees the minimum amount of bandwidth provided to each user without dropping any data at the base‐station, when the network has sufficient resources. If the network does not have sufficient resources to provide minimum bandwidth guarantees to all users without dropping data, the proportional data dropper finds the optimal data drop rates within acceptable levels of QoS and thus avoids the inflexibility of absolute DiffServ approach. The optimal bandwidth allocation and data droppage problems are formulated as constrained nonlinear optimization problems and solved using efficient techniques. Simulations are performed to show that the proposed scheme exhibits the desirable features of absolute and relative DiffServ. Copyright © 2009 John Wiley & Sons, Ltd.     

Addressing the interdependence in providing fair and efficient bandwidth distribution in hybrid optical‐wireless networks

The convergence of optical and wireless technologies may offer a compelling network access infrastructure because these technologies combine major benefits such as large coverage in the wireless part and huge bandwidth in the optical part of the converged access network. The convergence of the passive optical networks with 4G wireless standards, such as the Worldwide Interoperability for Microwave Access and the Long Term Evolution, constitutes a quite attractive solution to meet the challenges of the modern bandwidth‐hungry access networks. One of the most important objective a modern access network has to address is the adequate bandwidth distribution to the final users. In addition, several other aims are emerged towards this goal, such as fairness and quality of service provisioning. The adversity of designing an efficient bandwidth distribution scheme for hybrid optical‐wireless access networks lies in the interdependence of both domains: the bandwidth distribution in the wireless domain depends on the optical transmission grant opportunities, while the bandwidth coordinator in the optical part has to be aware of the mobile user heterogeneity in the wireless domain. Moreover, the bandwidth decision‐making module in both networks has to be aware of providing a fair allocation independently of the number of mobile users or the traffic requests in the network. In this work, we endeavor to address the aforementioned challenges. A novel, fair, and efficient bandwidth distribution scheme is proposed for hybrid optical‐wireless access networks. By using weighted fairness provisioning techniques, the proposed scheme intends to alleviate the interdependence of the two domains, offering a fair and efficient bandwidth distribution to the mobile users. The weights are properly defined, by utilizing suitable optimization techniques such as the Lagrange multiplies, so as to incorporate the underlying features of each traffic requests, such as the population density and the propagation delay. Extensive simulation results indicate the capability of the proposed scheme, compared with other competitive allocation schemes, in provisioning a more efficient and fair bandwidth distribution in terms of latency, throughput, and packet drop ratio. Copyright © 2015 John Wiley & Sons, Ltd.     

Bitcoin's dynamic peer‐to‐peer topology

Topology discovery is a prerequisite when investigating the network properties; with the enormous number of Bitcoin users and performance issues, it becomes critical to analyse the network in a fashion that makes it possible to detect all Bitcoin's nodes and understand their behaviour. In massive, dynamic, and distributed peer‐to‐peer (P2P) networks like Bitcoin, where thousands of updates occur per second, it is hard to obtain an accurate topology representing the structure of the network as a graph with nodes and links by using the traditional local measurement approaches based on batches, offline data, or on the discovery of the topology around a small set of nodes and then combine them to discover an approximate network topology. All of which present some limitation when applying them on blockchain‐based networks. In this paper, we propose a topology discovery system that performs a real‐time data collection and analysis for Bitcoin P2P links, which assembles incoming nodes information for deeper graph analysis processing. The topology discovery system allows us to gain knowledge on the Bitcoin network size, the network stability in terms of reachable, churn, and well‐connected nodes, as well as some data regarding the effects of some countries' Internet infrastructure on Bitcoin traffic.     

An analysis of user behavior in a private BitTorrent community

This paper aims to develop an understanding on how users of private BitTorrent communities participate in downloading and uploading by using the download records of CHDBits, one of the largest private BitTorrent communities in China. First, we investigate the arrivals of CHDBits users, which correspond to the initiations of new download tasks. The investigation demonstrates that user arrival rate varies with time in a day, and this variation dovetails well into users’ daily schedule. Moreover, we observe that it is with more than half possibility that the two consecutive arrivals of a CHDBits user take place in the same day, and that an individual user issues new download tasks with a probability of 0.23, on which we base to estimate that all CHDBits users are expected to launch at least one new download task in 42 days. Second, we present an analysis on the post‐download behavior of users. We observe that the average per task seeding time of 99% of users is no less than 8 h, showing CHDBits users’ great willingness to contribute. We also find that almost all the seeding processes have been interrupted and resumed multiple times. Finally, we study the bandwidth distribution of users and evaluate users’ bandwidth utilization in the downloading process. Our study shows that the bandwidths of most CHDBits users are uniformly distributed in the range from 256 kB/s to 16 MB/s, and users with a higher bandwidth tend to experience a lower bandwidth utilization. Copyright © 2012 John Wiley & Sons, Ltd.     

Minimizing File Download Time in Stochastic Peer-to-Peer Networks

The peer-to-peer (P2P) file-sharing applications are becoming increasingly popular and account for more than 70% of the Internet's bandwidth usage. Measurement studies show that a typical download of a file can take from minutes up to several hours depending on the level of network congestion or the service capacity fluctuation. In this paper, we consider two major factors that have significant impact on average download time, namely, the spatial heterogeneity of service capacities in different source peers and the temporal fluctuation in service capacity of a single source peer. We point out that the common approach of analyzing the average download time based on average service capacity is fundamentally flawed. We rigorously prove that both spatial heterogeneity and temporal correlations in service capacity increase the average download time in P2P networks and then analyze a simple, distributed algorithm to effectively remove these negative factors, thus minimizing the average download time. We show through analysis and simulations that it outperforms most of other algorithms currently used in practice under various network configurations.