LION: Layered Overlay Multicast With Network Coding

Recent advances in information theory show that the throughput of a multicast session can be improved using network coding. In overlay networks, the available bandwidth between sender and different receivers are different. In this paper, we propose a solution to improve the throughput of an overlay multicast session with heterogeneous receivers by organizing the receivers into layered data distribution meshes and sending substreams to each mesh using layered coding. Our solutions utilize alternative paths and network coding in each mesh. We first formulate the problem into a mathematical programming, whose optimal solution requires global information. We therefore present a distributed heuristic algorithm. The heuristic progressively organizes the receivers into layered meshes. Each receiver can subscribe to a proper number of meshes to maximize its throughput by fully utilizing its available bandwidth. The benefits of organizing the topology into layered mesh and using network coding are demonstrated through extensive simulations. Numerical results indicate that the average throughput of a multicast session is significantly improved (up to 50% to 60%) with only slightly higher delay and network resource consumption.     

基于集成FEC和层次传输的可靠组播的流控技术

端系统能力和网络带宽的异构性给大规模组播的流控带来很大困难。本文将前向纠错（ＦＥＣ）技术与层次传输相结合,较好地解决了异构环境下可靠组播的流控问题。我们给出了传输调度和信道速率分配的算法,讨论了差错控制问题。性能分析和模拟表明,该方法对大规模、异构组播组可显著减少平均传输时间并且有效地利用网络带宽。只需较少数目的组播组就能得到性能的很大提高。软件ＦＥＣ编码器的速度能够匹配当前的网络条件,算法易于实     

多组共享式应用层组播算法

利用单播传输路径的重叠特性所构建的叠加组播树可以部分模拟IP层的有源组播,而单组会话中成员主机在网络中分布的不足可以通过多组会话中的主机来弥补。该文根据这一特点提出了一种基于多组会话成员共享的应用层组播算法,该方法采用了源主机和接收主机之间的单播传输路径和多组协作机制,为每个组播源建立单独的组播树。通过模型分析,该文算法所构建的组播树可以比单组会话计算方法获得较大优势的链路利用率。     

On Bandwidth-Efficient Overlay Multicast

In this paper, we propose a new multicast delivery mechanism for bandwidth-demanding applications in IP networks. Our mechanism, referred to as multiple-destination overlay multicast (MOM), combines the advantages of IP multicast and overlay multicast. We formulate the MOM routing problem as an optimization problem. We then design an algorithm based on Lagrangian relaxation on our formulation and propose a distributed protocol based on the algorithm. For network operators, MOM consumes less network bandwidth than both IP multicast and overlay multicast. For users, MOM uses less interface bandwidth than overlay multicast.     

Extending RSVP for quality of security service

The resource reservation protocol (RSVP) lets hosts request quality of (bandwidth) service for multicast applications on the Internet. As network equipment advances to provide improved bandwidth service, security service becomes the more critical problem. However, RSVP doesn't provide a flexible mechanism to support quality of security service (QoSS). Security service RSVP extends RSVP to provide the needed mechanism for dynamically negotiating QoSS among the senders and receivers of multicast applications on the Internet. SSRSVP provides different QoSS resolutions according to receiver nodes' security service needs.     

基于单密钥的特定源多播安全机制

由于多播网络体系结构中多播数据发送不是点对点的方式,因此传统的端到端的安全不适合多播网络体系结构.在多播数据发送前,多播数据的接收者只要公布自己的公/私钥对中的公钥以及在发送加入组成员消息时告诉多播数据的发送者它的一个密钥,而无须知道多播源发送数据的加密密钥;多播数据发送者在每一次发送多播数据时,随机地选出一个密钥对发送的信息进行加密,但该密钥不是直接告诉多播数据接收者;接收者在进行解密数据时,首先必须利用自己的私钥以及发送给多播数据发送者的密钥求得加密数据的密钥,然后才能进行原文解密.     

Fair allocation of utilities in multirate multicast networks: aframework for unifying diverse fairness objectives

We study fairness in a multicast network. We assume that different receivers of the same session can receive information at different rates. We study a fair allocation of utilities, where the utility of a bandwidth is an arbitrary function of the bandwidth. The utility function is not strictly increasing, nor continuous in general. We discuss fairness issues in this general context. Fair allocation of utilities can be modeled as a nonlinear optimization problem. However, nonlinear optimization techniques do not terminate in a finite number of iterations in general. We present an algorithm for computing a fair utility allocation. Using specific fairness properties, we show that this algorithm attains global convergence and yields a fair allocation in polynomial number of iterations     

LVMSR: an efficient algorithm to multicast layered video

Layered video is a video-compression technique to encode video data in multiple layers. It typically consists of a base layer and some additional layers that provide enhanced video quality. The multicasting operation of layered video consists of many receivers dynamically joining and leaving different multicast sessions of different layers depending on their network condition. A layered video multicasting system needs to satisfy: (i) bounded end-to-end delay from the video source to each receiver; (ii) minimum total cost; and (iii) minimum delay jitter between the various video streams received by each receiver. The problem of computing such data distribution paths is NP-complete. This paper presents a new heuristic algorithm, called layered video multicast super-tree routing algorithm, with O(Rn²) time complexity and O(R²) message complexity, where n is the number of nodes in the network and R is the receiver group size. Our investigation shows that the multicast data paths computed by our algorithm can always satisfy the delay constraint with reasonably low total cost.     

异构网络环境下的高稳定性应用层组播方案

针对异构网络环境中由于节点转发能力异构而引起的应用层组播稳定性不足的问题,对异构overlay拓扑建模进行了研究,分析出组播稳定所需满足的约束条件,提出了一种基于gossip协作机制的应用层组播方案。在所提机制能够均衡节点间负载,缓解能力弱的节点负载过重的问题;如果组播过程中有成员节点动态离开或转发能力不足,其他节点相互协作共同分担其负载以维持组播的稳定性。随后的链路强度分析表明,与传统的应用层组播方案相比,本方案能够大幅降低拓扑的平均链路强度,提高组播系统的稳定性。最后通过OMNeT 仿真平台对本方案进行仿真验证,实验证明在动态的异构overlay拓扑下,本方案能够显著提高数据分发成功率,保证组播的连续性和稳定性。     

Discrete bandwidth allocation considering fairness and transmission load in multicast networks

As a promising solution to tackle the network heterogeneity in multicasting, layered multicast protocols such as receiver-driven layered multicast (RLM) and layered video multicast with retransmission (LVMR) have been proposed. This paper considers fairness as well as transmission load in the layered multicasting. Lexicographically fair bandwidth allocation among multicast receivers is considered under the constraint of minimum bandwidth requirement and the link capacity of the network. The problem of transmission load in the layer multicasting due to various user requirements is also examined by minimizing the number of layers.     

A Scalable Overlay Multicast Architecture for Large-Scale Applications

In this paper, we propose a two-tier overlay multicast architecture (TOMA) to provide scalable and efficient multicast support for various group communication applications. In TOMA, multicast service overlay network (MSON) is advocated as the backbone service domain, while end users in access domains form a number of small clusters, in which an application-layer multicast protocol is used for the communication between the clustered end users. TOMA is able to provide efficient resource utilization with less control overhead, especially for large-scale applications. It also alleviates the state scalability problem and simplifies multicast tree construction and maintenance when there are large numbers of groups in the network. To help MSON providers efficiently plan backbone service overlay, we suggest several provisioning algorithms to locate proxies, select overlay links, and allocate link bandwidth. Extensive simulation studies demonstrate the promising performance of TOMA     

Buffer-assisted on-demand multicast for VOD applications

Multicast communications is widely used by streaming video applications to reduce both server load and network bandwidth. However, receivers in a multicast group must access the multicast stream simultaneously, and this restriction on synchronous access diminishes the benefit of multicast because users in a video-on-demand service usually issue requests asynchronously, i.e., at anytime. In this paper, we not only formulate this streaming problem but also propose a new multicast infrastructure, called buffer-assisted on-demand multicast, to allow receivers accessing a multicast stream asynchronously. A timing control mechanism is integrated on intermediate routing nodes (e.g., routers, proxies, or peer nodes in a peer-to-peer network) to branch time-variant multicast sub-streams to corresponding receivers. Besides, an optimal routing path and the corresponding buffer allocations for each request must be carefully determined to maximize the throughput of the multicast stream. We prove that the time complexity to solve this routing problem over general graph networks is NP-complete, and then propose a routing algorithm for overlay networks to minimize server load. Simulation results demonstrate that buffer-assisted on-demand multicast outperforms many popular streaming methods.     

Island Multicast: Combining IP Multicast With Overlay Data Distribution

Traditional overlay protocols use unicast connections to form delivery trees. While it can achieve global multicast across the Internet, it is not as efficient as IP multicast. In this paper, we integrate IP multicast into overlay data distribution to improve delivery efficiency. We investigate island multicast where unicast connections are used to connect multicast domains and IP multicast is used within multicast domains. We first explore a centralized island multicast protocol (termed CIM), which relies on a central server to construct a delivery tree. We then study a distributed protocol (termed DIM), where hosts can distributedly join islands and form a delivery tree. We study the key issues in both protocols. We also discuss how to apply these protocols to media streaming applications. We have evaluated both protocols on Internet-like topologies. We have also implemented a prototype for CIM and tested it on PlanetLab. The results show that our approaches can significantly im prove network performance as compared to pure overlay protocols. Our study shows that it is important to consider local multicast capability when designing overlay protocols.     

基于用户行为分析的应用层组播树生成算法

应用层组播采用终端主机转发数据的方式,在一对多的媒体内容分发方面具有广阔的应用前景．与IP组播相比,应用层组播具有灵活和易实施的特点,但是因为终端主机可以自由地退出组播树,应用层组播也存在数据传递易中断的缺点,这对实时性要求严格的视频直播应用的影响尤为严重．通过对超过1000万条实际视频直播系统的真实用户记录进行统计分析,发现用户平均剩余在线时间随着已经在线时间的增大而增大,并据此提出了一种适用于视频直播的应用层组播树生成算法．模拟结果表明,算法对减少视频直播应用下应用层组播树的数据传递中断次数有明显作用．     

Evolutionary algorithms for route selection and rate allocation in multirate multicast networks

In multirate multicasting, different users (receivers) in the same multicast group can receive service at different rates, depending on the user requirements and the network congestion level. Compared with unirate multicasting, this provides more flexibility to the users and allows more efficient usage of the network resources. In this paper, we simultaneously address the route selection and rate allocation problem in multirate multicast networks; that is, the problem of constructing multiple multicast trees and simultaneously allocating the rate of receivers for maximizing the sum of utilities over all receivers, subject to link capacity and delay constraints for high-bandwidth delay-sensitive applications in point-to-point communication networks. We propose a genetic algorithm for this problem and elaborate on many of the elements in order to improve solution quality and computational efficiency in applying the proposed methods to the problem. These include the genetic representation, evaluation function, genetic operators, and procedure. Additionally, a new method using an artificial intelligent search technique, called the coevolutionary algorithm, is proposed to achieve better solutions, and methods of selecting environmental individuals and evaluating fitness are developed. The results of extensive computational simulations show that the proposed algorithms provide high-quality solutions and outperform existing approach.     

基于能量优化的认知无线电网络组播路由协议

针对认知无线电网络节点动态频谱分配的特点,利用静态博弈方法,根据次用户占用频谱越宽所造成干扰越大,建立基于价格惩罚机制的古诺模型解决频谱分配问题,通过求解纳什均衡,频谱利用率达到最优。根据最小增量按需驱动思想建立了节约能量的组播树,提出基于能量优化的适用于认知无线电网络的按需组播路由协议。     

一种基于效用最优的分层多播动态层速率分配算法

分层多播已被认为是在Internet上进行视频多播的一个解决方案．已有的分层多播协议通常在接收方执行层的适应,在发送方使用静态的层速率分配技术．首先介绍了分层多播的基本原理,讨论了接收方驱动的静态分层与发送方驱动的动态分层技术,特别地引入了一种衡量尺度“效用”对多媒体应用满意度进行度量;提出了一种效用最优的层速率分配算法ORAU,并通过推理证明得出了一个求解途径;接着给出了ORAU算法的实现;最后对ORAU算法在特定的网络环境中进行了实验仿真,并对仿真结果与其他算法进行了比较分析．实验结果表明,采用ORAU算法的多媒体多播系统能够花费较小的带宽就可以获得相对较高的系统效用,验证了算法的可行性和有效性．     

主动结点启动的可靠多播通信

一、概述在Internet网上实现多播通信还存在没有完全解决的技术问题,如反馈信息爆炸、丢失数据局部恢复功能等,针对这些问题目前有两个主要研究方向:定时器方法(如SRM)和等级结构化方法(如RMTP),但它们都只能部分地解决这些问题。     

RSVP协议上的ELSD代价分配方案

本文讨论ＲＳＶＰ协议（资源保留协议）在多点播送分布树环境下的ＥＬＳＤ代价分配方案,问题是,当一个数据流在多个接收者之间共享时,如何在使用者之间分割充的网络代价,根据ＲＳＶＰ协议所能建立的三种不同的资源保留类型,本文分别给出了简单ＥＬＳＤ和加权ＥＬＳＤ两种不同的代价分配方案,以求得在接收者之间公正,合理地分配代价,达到制约使用者合理使用资源的目的。