Fair internet traffic integration: network flow models and analysis

We use flow-level models to study the integration of two types of Internet traffic, elastic file transfers and streaming traffic. Previous studies have concentrated on just one type of traffic, such as the flow level models of Internet congestion control, where network capacity is dynamically shared between elastic file transfers, with a randomly varying number of such flows. We consider the addition of streaming traffic in two cases, under a fairness assumption that includestcp-friendliness as a special case, and under certain admission control schemes. We establish sufficient conditions for stability, using a fluid model of the system. We also assess the impact of each traffic type on the other: file transfers are seen by streaming traffic as reducing the available capacity, whereas for file transfers the presence of streaming traffic amounts to replacing sharp capacity constraints by relaxed constraints. Simulation results suggest that the integration of streaming traffic and file transfers has a stabilizing effect on the variability of the number of flows present in the system.     

Deadline‐aware TCP congestion control for HTTP adaptive streaming services

Over the last decades, video streaming services have gained a lot of popularity, representing over 70% of the total consumer Internet traffic worldwide. While originally dedicated streaming protocols have been used to deliver these services, for several years, the video streaming industry is steadily shifting to HTTP adaptive streaming (HAS)–based delivery over TCP. With each video segment, implicit delivery deadlines are associated in order to avoid playout interruptions. However, TCP is known to be far from minimizing the number of deadline‐missing streams. In this paper, 2 deadline‐aware congestion control mechanisms are proposed, based on a parametrization of the traditional TCP New Reno congestion control strategy. By introducing deadline awareness at the transport layer, the modulation of the congestion window size is dynamically adapted to steer the aggressiveness of the considered stream to optimize the delivery of video streaming services. The proposed approaches are thoroughly evaluated in an HAS video‐on‐demand scenario over tree‐based delivery networks. It was shown that in a realistic scenario, the proposed approaches can outperform traditional congestion control strategies by up to 12% in terms of estimated mean opinion score, mainly by reducing the average video freezing time by more than 85%.     

IPTV over P2P streaming networks: the mesh-pull approach

IPTV, an emerging Internet application, would revolutionize the entertainment and media industries; however, IPTV also has the potential to overwhelm the Internet backbone and access networks with traffic. To date, IPTV over P2P streaming networks has advanced significantly using two different approaches: tree-push versus mesh-pull. In particular, the mesh-pull streaming approach has achieved a number of successful commercial deployments. In this article, we examine the current progress in the research and development of mesh-pull P2P streaming systems. We provide an overview of the general mesh-pull streaming architecture and review various challenges, design issues, and interesting research problems in this approach. We discuss the construction costs for providing an IPTV service with service guarantees. We outline a measurement technique for monitoring the video playback quality of mesh-pull streaming systems. We emphasize that the future P2P IPTV systems should be designed to meet the expectations of users for quality-of-experience. We also identify a few other important issues for IPTV over P2P streaming networks, including the traffic pressure on ISPs, various security concerns, and the necessity to re-examine the most appropriate P2P architecture. Insights obtained in this study will be valuable for the development and deployment of future P2P IPTV systems.     

A survey on TCP-friendly congestion control

New trends in communication, in particular the deployment of multicast and real-time audio/video streaming applications, are likely to increase the percentage of non-TCP traffic in the Internet. These applications rarely perform congestion control in a TCP-friendly manner; they do not share the available bandwidth fairly with applications built on TCP, such as Web browsers, FTP, or e-mail clients. The Internet community strongly fears that the current evolution could lead to congestion collapse and starvation of TCP traffic. For this reason, TCP-friendly protocols are being developed that behave fairly with respect to coexistent TCP flows. We present a survey of current approaches to TCP friendliness and discuss their characteristics. Both unicast and multicast congestion control protocols are examined, and an evaluation of the different approaches is presented     

An Efficient QoE-Aware HTTP Adaptive Streaming over Software Defined Networking

Due to the increase in video streaming traffic over the Internet, more innovative methods are in demand for improving both Quality of Experience (QoE) of users and Quality of Service (QoS) of providers. In recent years, HTTP Adaptive Streaming (HAS) has received significant attention from both industry and academia based on its impacts on the enhancement of media streaming services. However, HAS-alone cannot guarantee a seamless viewing experience, since this highly relies on the Network Operators’ infrastructure and evolving network conditions. Along with the development of future Internet infrastructure, Software-Defined Networking (SDN) has been researched and newly implemented as a promising solution in improving services of different Internet layers. In this paper, we present a novel architecture incorporating bitrate adaptation and dynamic route allocation. At the client side, adaptation logic of VBR videos streaming is built based on the MPEG-DASH standard. On the network side, an SDN controller is implemented with several routing strategies on top of the OpenFlow protocol. Our experimental results show that the proposed solution enhances at least 38% up to 185% in term of average bitrate in comparison with some existing solutions as well as achieves better viewing experience than the traditional Internet.

     

An efficient modeling and dimensioning approach for integrated streaming and elastic traffic

Recent studies show that both data traffic and real-time traffic grow very fast in wired and wireless networks. To provide better performance guarantee, these applications need efficient network modeling and planning. In this paper, the problem where the total bandwidth of a link is shared by streaming traffic (real time traffic such as voice or video etc.) and elastic traffic (such as data) is studied. Integrating streaming traffic and elastic traffic presents a unique dimensioning problem. This paper considers dimensioning a link to satisfy both quality of service (QoS) requirements for streaming traffic, such as loss probability, and elastic traffic, such as mean waiting (delay) time. The Erlang loss model is applied to streaming traffic and a bursty traffic model is applied to the elastic traffic. Efficient dimensioning algorithms based on classical Markovian models and time-scale decomposition are then proposed. Numerical results show that the proposed methods have good accuracy.     

Ergodic Sum Rate Maximization for Underlay Spectrum Sharing with Heterogeneous Traffic

A radio resource allocation framework is proposed for underlay spectrum sharing. The ergodic capacity maximization problem in orthogonal frequency division multiple access-based network on point to multi point transmission is formulated and solved. Heterogeneous traffic is also considered in which two types of traffic is assumed: streaming traffic which has strict delay requirements, and elastic traffic with flexible delay requirements. Considering the effect of channel state information (CSI) imperfection in the evaluation of the secondary users’ expected rate, we further assume that the estimated CSI between the secondary users and secondary base station (secondary channel) is not perfect. Moreover three different cases are considered depending on the availability of the CSI between the secondary base station and the primary receivers (interference channel). Using simulations, we evaluate the impact of streaming traffic and imperfect CSI on the sum capacity of the secondary elastic users for different values of parameter systems.     

Proxy caching for media streaming over the Internet

Streaming media has contributed to a significant amount of today's Internet traffic. Like conventional Web objects (e.g., HTML pages and images), media objects can benefit from proxy caching; but their unique features such as huge size and high bandwidth demand imply that conventional proxy caching strategies have to be substantially revised. This article discusses the critical issues and challenges of cache management for proxy-assisted media streaming. We survey, classify, and compare the state-of-the-art solutions. We also investigate advanced issues of combining multicast with caching, cooperating among proxies, and leveraging proxy caching in overlay networks.     

A survey of research on the application-layer traffic optimization problem and the need for layer cooperation - [Accepted from open call]

A significant part of Internet traffic today is generated by peer-to-peer applications, used traditionally for file sharing, and more recently for real-time communications and live media streaming. Such applications discover a route to each other through an overlay network with little knowledge of the underlying network topology. As a result, they may choose peers based on information deduced from empirical measurements, which can lead to suboptimal choices. We refer to this as the applicationlayer traffic optimization (ALTO) problem and present a survey of existing literature. We summarize and compare existing approaches, identify open research issues, and state the need for layer cooperation as a solution to the ALTO problem.     

基于嵌入式流媒体服务器的视频点播系统

移动通信网络流媒体服务资费较高,限制了人们在没有有线电视、宽带互联网连接、无线WiFi互联网连接的地方用手机收看视音频节目.针对这一现状,提出了一种基于嵌入式流媒体服务器的多功能视频点播系统.以ARM板和WiFi网络适配器作为流媒体服务器,设计一款Android手机播放器作为客户端,实现在智能手机上、多个客户端同时免流量接收服务器本地或外接设备推送的高清、超高清视频.该系统适用于公交、广场、电梯、商场、景区等场合,人们用手机观看视音频,实现不用耗费自己的流量,自由快速地选择自己喜欢的节目.     

Using Quick‐Start to enhance TCP‐friendly rate control performance in bidirectional satellite networks

In the not so distant future, we envisage an Internet where the biggest share of capacity is used by streaming applications. To avoid congestion collapse from unresponsive flows calls for a robust and ubiquitous end‐to‐end multimedia congestion control mechanism, such as TCP‐friendly rate control (TFRC), which provides fair sharing with the other Internet traffic. This paper therefore analyses the implications of using rate‐adaptive congestion control over satellite links that utilize demand allocation multiple access (DAMA) to maximize satellite transponder utilization. The interaction between TFRC and DAMA is explored using simulations supported by fluidic flow models. The analysis shows that DAMA reduces the start‐up phase of TFRC, causing non‐negligible delays. To mitigate this problem, we propose a new cross‐layer method based on the Quick‐Start mechanism. This can accelerate the start‐up of multimedia flows by a judicious allocation of additional capacity derived from cross‐layer signalling. Copyright © 2009 John Wiley & Sons, Ltd.     

Challenges and Approaches in Large-Scale P2P Media Streaming

Large-scale multimedia streaming over the Internet requires an enormous amount of server and network resources. Traditional client-server approaches allocate a dedicated stream from the server for each client request, which is expensive and doesn't scale well. By using end hosts' huge bandwidth and computational capacity, peer-to-peer technologies shed new light on media streaming applications' development. Yet, locating supplying peers and content delivery path maintenance are two major challenges in this area     

Evaluating the impact of emerging streaming media applications onTCP/IP performance

Emerging streaming media applications in the Internet primarily use UDP transport. The difficulty with supporting this type of traffic on the Internet is that they not only generate large volumes of traffic, but they are also not as responsive to network congestion as TCP-based applications. As a result, streaming media UDP traffic can cause two major problems in the Internet: congestion collapse and unfair allocations of bandwidth among competing traffic flows. A solution to these problems is available in many Internet environments. The Internet backbone, various ISPs, and DSL access networks rely on ATM as their layer 2 transport technology, and in such environments, ATM's available bit rate service can efficiently address these problems. ABR is able to avoid congestion collapse and provide fair bandwidth allocations by distributing the unutilized bandwidth fairly among competing flows. This article presents simulation results and empirical measurements that illustrate the congestion collapse and unfairness problems, and ATM ABR's effectiveness in addressing those problems     

Application of active queue management for real-time adaptive video streaming

Telecommunication Systems - Video streaming currently dominates global Internet traffic. Live streaming broadcasts events in real-time, with very different characteristics compared to...     

Demand assigned capacity management (DACM) in IP over optical (IPO) networks

The demand assigned capacity management (DACM) problem in IP over optical (IPO) network aims at devising efficient bandwidth replenishment schedules from the optical domain conditioned upon traffic evolution processes in the IP domain. A replenishment schedule specifies the location, sizing, and sequencing of link capacity expansions to support the growth of Internet traffic demand in the IP network subject to economic considerations. A major distinction in the approach presented in this paper is the focus of attention on the economics of "excess bandwidth" in the IP domain, which can be viewed as an inventory system that is endowed with fixed and variable costs and depletes with increase in IP traffic demand requiring replenishment from the optical domain. We develop mathematical models to address the DACM problem in IPO networks based on a class of inventory management replenishment methods. We apply the technique to IPO networks that implement capacity adaptive routing in the IP domain and networks without capacity adaptive routing. We analyze the performance characteristics under both scenarios, in terms of minimizing cumulative replenishment cost over an interval of time. For the non-capacity adaptive routing scenario, we consider a shortest path approach in the IP domain, specifically OSPF. For the capacity adaptive scenario, we use an online constraint-based routing scheme. This study represents an application of integrated traffic engineering which concerns collaborative decision making targeted towards network performance improvement that takes into consideration traffic demands, control capabilities, and network assets at different levels in the network hierarchy.     

Managing capacity for telecommunications networks under uncertainty

The existing telecommunications infrastructure in most of the world is adequate to deliver voice and text applications, but demand for broadband services such as streaming video and large file transfer (e.g., movies) is accelerating. The explosion in Internet use has created a huge demand for telecommunications capacity. However, this demand is extremely volatile, making network planning difficult. Modern financial option pricing methods are applied to the problem of network investment decision timing. In particular, we study the optimal decision problem of building new network capacity in the presence of stochastic demand for services. Adding new capacity requires a capital investment, which must be balanced by uncertain future revenues. We study the underlying risk factor in the bandwidth market and then apply real options theory to the upgrade decision problem. We notice that sometimes it is optimal to wait until the maximum capacity of a line is nearly reached before upgrading directly to the line with the highest known transmission rate (skipping the intermediate lines). It appears that past upgrade practice underestimates the conflicting effects of growth and volatility. This explains the current overcapacity in available bandwidth. To the best of our knowledge, this real options approach has not been used previously in the area of network capacity planning. Consequently, we believe that this methodology can offer insights for network management.     

叶脊架构在数据中心的应用

目前,互联网数据中心数据量主要集中在PB/EB级别,在采取虚拟化技术之后,东西流量大幅增加,给传统三层架构带来很大挑战.叶脊架构将网络从三层扁平化为二层,更适于数据中心内部流量的高效运转,帮助企业充分发挥网络的优势,寻求数据中心效用的最大化,提升资源利用率.叶脊架构对整个高端光模块的应用数量是传统架构的数十倍,将强势拉...     

Beyond folklore: observations on fragmented traffic

Fragmented IP traffic is a poorly understood component of the overall mix of traffic on the Internet. Many assertions about the nature and extent of fragmented traffic are anecdotal rather than empirical. In this paper we examine the causes and attributes of measured fragment traffic, in particular, the effects of NFS, streaming media, networked video games, tunneled traffic, and the prevalence of packet fragmentation due to improperly configured machines. To understand the prevalence, causes, and effects of fragmented IP traffic, we have collected and analyzed seven multiday traces from four sources. These sources include a university commodity access link, two highly aggregated commercial exchange points, and a local NAP. Although there is no practical method of ascertaining whether any data provide a representative sample of all Internet traffic, we include data sources that cover several different types of WAN with traffic from commercial entities, educational and research institutions, and large government facilities. The dominant causes of fragmentation are streaming media and tunneled traffic. Although rumored to be the main impetus for IP packet fragmentation, NFS is not among the top ten causes.     

Adaptive systems for improved media streaming experience

Supporting streaming media applications over current packet network infrastructures represents a challenging task in many regards. For one, the lack of quality of service (QoS) guarantees in existing networks such as the Internet means that time-constrained media packets will face dynamic variations in bandwidth, loss rate, and delay as they traverse the network from the sender to the receiver. The variable rate of media traffic represents yet another difficulty when transmission constraints need to be met. Finally, the heterogeneity of client devices and access bandwidth coupled with custom user preferences exacerbate the problem of smooth and quality-optimized media playback even further. In this article we provide an overview of the various techniques for media and streaming strategy adaptation, which can be employed to deal with the difficulties imposed by such dynamic environments. These techniques depend on the characteristics of the media application, in particular on the network streaming infrastructure and the timing constraints imposed on the media packets' delivery. We survey adaptation techniques that act on the encoding of the multimedia information, on the scheduling of the media packets, or that try to combat transmission errors. We also briefly overview some media-friendly networking solutions, which contribute to increased QoS by incorporating some level of intelligence in intermediate network nodes. Finally, we describe a few open challenges in media streaming, emphasizing strategies based on promising cross-layer approaches where adaptation strategies are applied in a coordinated manner, across different layers of the network protocol stack     

Reliable Multimedia Transmission Over Cognitive Radio Networks Using Fountain Codes

With the explosive growth of wireless multimedia applications over the wireless Internet in recent years, the demand for radio spectral resources has increased significantly. In order to meet the quality of service, delay, and large bandwidth requirements, various techniques such as source and channel coding, distributed streaming, multicast etc. have been considered. In this paper, we propose a technique for distributed multimedia transmission over the secondary user network, which makes use of opportunistic spectrum access with the help of cognitive radios. We use digital fountain codes to distribute the multimedia content over unused spectrum and also to compensate for the loss incurred due to primary user interference. Primary user traffic is modelled as a Poisson process. We develop the techniques to select appropriate channels and study the trade-offs between link reliability, spectral efficiency and coding overhead. Simulation results are presented for the secondary spectrum access model.