Fine-grained Layered multicast with STAIR

Traditional approaches to receiver-driven layered multicast have advocated the benefits of cumulative layering, which can enable coarse-grained congestion control that complies with TCP-friendliness equations over large time scales. In this paper, we quantify the costs and benefits of using noncumulative layering and present a new, scalable multicast congestion control scheme called STAIR that embodies this approach. Our first main contribution is a set of performance criteria on which we base a comparative evaluation of layered multicast schemes. In contrast to the conventional wisdom, we demonstrate that fine-grained rate adjustment can be achieved with only modest increases in the number of layers, aggregate bandwidth consumption and control traffic. The STAIR protocol that we subsequently define and evaluate is a multiple rate congestion control scheme that provides a fine-grained approximation to the behavior of TCP additive increase/multiplicative decrease (AIMD) on a per-receiver basis.     

基于网络控制的分层多点播送速率控制机制研究

本文在视频分层编码及分层传输协议的基础上，将基于网络控制与接收端控制机制相结合，提出一种新的分层多点播送速率控制机制。文中给出了该机制的拥塞检测、流行度权衡和数据层增加和丢弃算法。实验结果表明，该速率控制机制通史对拥塞做也快速响应，并在较好利用宽带的基础上保证高流行度的会话流具有较好的服务质量。     

一种新的多速率多播拥塞控制策略

本文提出了一种新的多速率多播拥塞控制策略,以满足分层多播接收者的可用带宽异构性。这种接收方驱动的拥塞控制策略,能够根据网络情况变化动态地调整分层的数量及层速率,运用最优层速率分配算法来满足接收者的可用带宽异构性,接收者的可用带宽可以用根据TCP友好经验公式计算出。仿真实验表明,该算法在TCP友好性上有良好的性能,同时它可以明显提高系统的吞吐量。     

Application versus network layer multicasting in ad hoc networks: the ALMA routing protocol

Application layer multicasting has emerged as an appealing alternative to network layer multicasting in wireline networks. Here, we examine the suitability of application layer multicast in ad hoc networks. To this effect, we propose a flexible receiver-driven overlay multicast protocol which we call Application Layer Multicast Algorithm (ALMA). ALMA constructs an overlay multicast tree in a dynamic, decentralized and incremental way. First, ALMA is receiver-driven: the member nodes find their connections according to their needs. Second, it is flexible, and thus, it can satisfy the performance goals and the needs of a wide range of applications. Third, it is highly adaptive: it reconfigures the tree in response to mobility or congestion. In addition, our protocol has the advantages of an application layer protocol: (a) simplicity of deployment, (b) independence from lower layer protocols, and (c) capability of exploiting features such as reliability and security that may be provided by the lower layers. Through extensive simulations, we show that ALMA performs favorably against the currently best application layer and network layer protocols. In more detail, we find that ALMA performs significantly better than ODMRP, a network layer, for small group sizes. We conclude that the application layer approach and ALMA seem very promising for ad hoc multicasting.     

Leveraging single rate schemes in multiple rate multicast congestion control design

A significant impediment to deployment of multicast services is the daunting technical complexity of developing, testing and validating congestion control protocols fit for wide-area deployment. Protocols such as pragmatic general multicast congestion control (pgmcc) and TCP-friendly multicast congestion control (TFMCC) have recently made considerable progress on the single rate case, i.e., where one dynamic reception rate is maintained for all receivers in the session. However, these protocols have limited applicability, since scaling to session sizes beyond tens of participants with heterogeneous available bandwidth necessitates the use of multiple rate protocols. Unfortunately, while existing multiple rate protocols exhibit better scalability, they are both less mature than single rate protocols and suffer from high complexity. We propose a new approach to multiple rate congestion control that leverages proven single rate congestion control methods by orchestrating an ensemble of independently controlled single rate sessions. We describe a new multiple rate congestion control algorithm for layered multicast sessions that employs a single rate multicast congestion control as the primary underlying control mechanism for each layer. Our new scheme combines the benefits of single rate congestion control with the scalability and flexibility of multiple rates to provide a sound multiple rate multicast congestion control policy.     

A Dynamic Adaptive Layered Multicast Congestion Control Mechanism

To solve the problem that most of existing layered multicast protocols cannot adapt todynamic network conditions because their layers are coarsely granulated and static,a new congestioncontrol mechanism for dynamic adaptive layered multicast(DALM) is presented.In this mechanism,anovel feedback aggregating algorithm is put forward,which can dynamically determine the number oflayers and the rate of each layer,and can efficiently improve network bandwidth utilization ratio.Additionally,because all layers is transmitted in only one group,the intricate and time-consuminginternet group management protocol(IGMP) operations,caused by receiver joining a new layer orleaving the topmost subscribed layer,are thoroughly eliminated.And this mechanism also avoids otherproblems resulted from multiple groups.Simulation results show that DALM is adaptive and TCPfriendly.     

The impact of multicast layering on network fairness

Many definitions of fairness for multicast networks assume that sessions are single rate, requiring that each multicast session transmits data to all of its receivers at the same rate. These definitions do not account for multirate approaches, such as layering, that permit receiving rates within a session to be chosen independently. We identify four desirable fairness properties for multicast networks, derived from properties that hold within the max-min fair allocations of unicast networks. We extend the definition of multicast max-min fairness to networks that contain multirate sessions, and show that all four fairness properties hold in a multirate max-min fair allocation, but need not hold in a single-rate max-min fair allocation. We then show that multirate max-min fair rate allocations can be achieved via intra-session coordinated joins and leaves of multicast groups. However, in the absence of coordination, the resulting max-min fair rate allocation uses link bandwidth inefficiently, and does not exhibit some of the desirable fairness properties. We evaluate this inefficiency for several layered multirate congestion control schemes, and find that, in a protocol where the sender coordinates joins, this inefficiency has minimal impact on desirable fairness properties. Our results indicate that sender-coordinated layered protocols show promise for achieving desirable fairness properties for allocations in large-scale multicast networks     

Revisiting the fair queuing paradigm for end-to-end congestion control

Today, the dominant paradigm for congestion control in the Internet is based on the notion of TCP friendliness. To be TCP-friendly, a source must behave in such a way as to achieve a bandwidth that is similar to the bandwidth obtained by a TCP flow that would observe the same round-trip time (RTT) and the same loss rate. However, with the success of the Internet comes the deployment of an increasing number of applications that do not use TCP as a transport protocol. These applications can often improve their own performance by not being TCP-friendly, which severely penalizes TCP flows. To design new applications to be TCP-friendly is often a difficult task. The idea of the fair queuing (FQ) paradigm as a means to improve congestion control was first introduced by Keshav (1991). While Keshav made a fundamental step toward a new paradigm for the design of congestion control protocols, he did not formalize his results so that his findings could be extended for the design of new congestion control protocols. We make this step and formally define the FQ paradigm as a paradigm for the design of new end-to-end congestion control protocols. This paradigm relies on FQ scheduling with per-flow scheduling and longest queue drop buffer management in each router. We assume only selfish and noncollaborative end users. Our main contribution is the formal statement of the congestion control problem as a whole, which enables us to demonstrate the validity of the FQ paradigm. We also demonstrate that the FQ paradigm does not adversely impact the throughput of TCP flows and explain how to apply the FQ paradigm for the design of new congestion control protocols. As a pragmatic validation of the FQ paradigm, we discuss a new multicast congestion control protocol called packet pair receiver-driven layered multicast (PLM).     

一种新的逐跳TCP友好的主动分层多播拥塞控制方案

基于Internet的多媒体多播应用的迅猛发展对多播拥塞控制提出了要求.分层多播是适应网络异构性较有效的方案.针对现有分层多播存在的问题,将主动网技术思想引入到分层多播拥塞控制中,提出了一种逐跳TCP友好的主动分层多播拥塞控制方案(HTLMA),采用主动标记分层、逐跳探测TCP友好可用带宽,以及主动速率控制机制.仿真实验表明,HTLMA方案大大改进了分层多播拥塞控制的性能,具有较快的拥塞响应速度、较好的稳定性和TCP友好特性.     

Achieving inter-session fairness for layered video multicast

The Internet is increasingly used to deliver multimedia services. Since there are heterogeneous receivers and changing network conditions, it has been proposed to use adaptive rate control techniques such as layered video multicast to adjust the video traffic according to the available Internet resources. A problem of layered video multicast is that it is unable to provide fair bandwidth sharing between competing video sessions. We propose two schemes, layered video multicast with congestion sensitivity and adaptive join-timer (LVMCA) and layered video multicast with priority dropping (LVMPD), to achieve inter-session fairness for layered video multicast. Receiver-driven layered multicast (RLM), layer-based congestion sensitivity, LVMCA, and LVMPD are simulated and compared. Results show both proposed schemes, especially LVMPD, are fairer and have shorter convergence time than the other two schemes.     

A survey of congestion control schemes for multicast video applications

Congestion control for IP multicast on the Internet has been one of the main issues that challenge a rapid deployment of IP multicast. In this article, we survey and discuss the most important congestion control schemes for multicast video applications on the Internet. We start with a discussion of the different elements of a multicast congestion control architecture. A congestion control scheme for multicast video possesses specific requirements for these elements. These requirements are discussed, along with the evaluation criteria for the performance of multicast video. We categorize the schemes we present into end-to-end schemes and router-supported schemes. We start with the end-to-end category and discuss several examples of both single-rate multicast applications and layered multicast applications. For the router-supported category, we first present single-rate schemes that utilize filtering of multicast packets by the routers. Next we discuss receiver-based layered schemes that rely on routers group?flow control of multicast sessions. We evaluate a number of schemes that belong to each of the two categories.     

一种新的分层多播拥塞控制协议

提出了一种新的自适应分层多播拥塞控制方案(ALM)。ALM是发送方与接收方共同驱动、由路由器辅助流量控制的拥塞控制方案,通过把发送方的动态分层和接收方的自适应速率调整有机结合,不仅增强了分层多播的适应能力,提高了系统的吞吐量,而且较好地满足了TCP友好性。仿真实验表明,ALM能有效地利用网络带宽,解决网络带宽的异构性问题,并能通过接收端计算TCP友好速率,使接收端达到与TCP流公平竞争网络资源的目的。     

SLM-一种安全分层组播协议

流媒体分发的一种典型实现方法是采用具有接收方驱动拥塞控制机制的分层组播.由于目前分层组播拥塞控制协议缺乏对用户行为的限制,接收方可违规订阅上层组播组发起自利型攻击,导致非公平的带宽利用.本文提出了一种较通用的安全分层组播协议SLM(Secure Layered Multicast).在路由器辅助拥塞控制条件下,在边界路由器采用基于Shamir秘密共享体制的拥塞状态相关访问控制(CR-AC,Congestion state Related Access Control)算法,管理用户组订阅行为,避免了用户自利型攻击,并使服务提供商可根据其与用户的协约限定不同用户的最高订阅级别.分析和仿真实验表明,该协议可实时保证网络流量安全共享带宽并具有较好的可扩展性.     

分层组播拥塞控制策略对组播树稳定性的影响

文章考察在分层组播拥塞控制环境下网络拥塞对组播树(单对多)稳定性的影响,定义一个稳定性因子来评估和量化这种影响.并提出一个简单的链路相关拥塞模型,得到稳定性因子的通用表达式.模拟结果表明,即使在链路标记概率较低的情况下,随着不同链路相关度的减小,拥塞对组播树稳定性会产生非常大的影响.     

新的多速率多播拥塞控制方案

提出了一种新的基于数据包束探测(packet-bunch probe)和TCP吞吐量公式的多速率多播拥塞控制方案PTMCC(packet-bunch probe and TCP-formula based multicast congestion control)。这种接收端驱动的拥塞控制,采用数据包束来探测网络的可用带宽,利用TCP吞吐量公式得到TCP友好速率,并采用了新的速率调节算法。仿真实验表明,PTMCC在收敛性、灵敏性以及TCP友好性上具有较好的性能。     

一种面向多媒体的TCP友善的分层组播拥塞控制协议

本文提出了一种面向多媒体的分层组播拥塞控制协议(Rate Adaptation at Receivers for Layered Multicast with Dynamic Layers),简称MRAAR-DL。该协议具有良好的TCP友善性和分层编码通用性。     

IP DSLAM上可控组播的实现

随着宽带接入的迅速普及,组播业务逐步得到应用,网络电视(IPTV)业务也正在走向商业运营,但是IPTV需要一个可控的组播对其提供支持,而组播协议并不是一个能对自身进行管理的协议.文章在介绍二层接入设备IP数字用户线接入复用器(IP DSLAM)上的组播协议的基础上,提出了一种在二级的IP DSLAM上如何支持可控组播的解决方案,并提供了详细的流程.     

Optimization-based congestion control for multicast communications

This article outlines an approach for multicast congestion control based on an economic model that has been successfully applied to unicast congestion control. In this model, congestion signals are interpreted as prices and congestion-controlled sessions as utility maximizing agents. A naive extension of the unicast model fails to achieve a reasonable balance between providing the incentives necessary to promote the use of multicast and ensuring that multicast sessions do not interact too aggressively with unicast sessions. We extend the model by introducing a rational definition of multicast utility. The revised model provides a basis for multicast congestion control protocols that provide incentives to use multicast but are necessarily unfair to unicast traffic. We show, however, that the degree of unfairness can be controlled by appropriately setting a design parameter with a limiting case of strict fairness     

On max-min fair congestion control for multicast ABR service in ATM

In the ATM Forum activities, considerable efforts have focused on the congestion control of point-to-point available bit rate (ABR) service. We present a novel approach that extends existing point-to-point (unicast) congestion control protocols to a point-to-multipoint (multicast) environment. In particular, we establish a unified framework to derive a multicast congestion control protocol for an ABR service from a given rate-based unicast protocol. We generalize a known necessary and sufficient condition on the max-min fairness of unicast rate allocation for a multicast service. Using this condition, we show that the resulting multicast protocol derived using our framework preserves the fairness characteristics of the underlying unicast protocol. The practical significance of our approach is illustrated by extending a standard congestion control mechanism for an ABR service to a multicast environment. The performance of the resulting multicast protocol is examined using benchmark network configurations suggested by the traffic management subworking group at the ATM Forum, and simulation results are presented to substantiate our claims