Study Of IP Over Optical Overlay Multicast Network For Supporting IPTV

IPTV is expected to be the next killer application in the telcos'triple-play service portfolio that will consume available bandwidth on the Internet and enable future network growth. Nowadays, many deployments have been announced by operators in the North American, European, and Asia/Pacific regions. In the IPTV system, multicasting will play a key role in the delivery of high-quality video services to optimize the utilization of network resources. There are three main types of multicast based on different layers of the network: IP, application layer and optical layer.China 3Tnet project employed a new IP over optical overlay multicast networks architecture for supporting IPTV service. The key idea of this architecture is that IP multicast flow is transferred in the core optical network through a light-tree. This overlay multicast architecture can achieve better scalability and QoS than traditional single layer IP multicasting. The dissertation focuses on some technique issues in overlay multicast networks. It mainly includes the implementation of overlay multicast networks, multi-tree multicast flow aggregation (MFA) under static traffic model, stability of MFA under the dynamical scenario, group-to-tree mapping within topology-unawared networks and the channel zapping in overlay multicast networks.The first chapter is an introductory and gives a brief overview on the research background of overlay multicast networks. Afterwards, this chapter also introduces the main content of this dissertation and technical problems to be addressed in this work.Chapter 2 covers the distributed control problem of optical multicast in overlay multicast networks. We extend the existing signaling protocol to support point-to-multipoint connections based on the OIF UNI specification. We also investigate the signaling extensions in GMPLS framework for supporting optical multicast.In chapter 3 we discuss multi-tree MFA under static traffic model. In the IPTV system, the same program may be redundantly provided by several head ends in the network. End users could choose different head end as its root according to current network condition, so called multi-tree. A heuristic algorithm is proposed to simply the multi-tree MFA problem through decomposing one channel with multiple head ends into several new requests which has single source. Thus, we can treat it as a normal MFA problem and try to minimize the total network resource usage.In chapter 4 we focus on the stability of MFA under the dynamical scenario. In the IPTV system, any light-trees reconfiguration, including both the combination of the aggregated programs and the routes of light-trees, may lead to degradation of quality of experience (QoE) for the end users, say, large latency of channel zapping or service interruption. We define and formulate the stable MFA problem. Afterwards, a two-stage heuristic algorithm is proposed to achieve better performance in terms of stability as well as network resource utilization.The group-to-tree mapping within topology-unawared networks is discussed in chapter 5. We formulate the problem on a random graph and get the relationship between the bandwidth overhead and the group members similarity. Therefore, we can use the group members similarity to do the group-to-tree mapping, which does not need any topology information.In chapter 6 we discuss the channel zapping problem in overlay multicast network for IPTV delivery. First, we introduce the channel zapping in contemporary IPTV system based on IP multicasting. After that, we demonstrate the network architecture and signaling procedure in overlay multicast network and discuss their influence on the channel zapping delay. Finally, we measure the network delay introduced by various signaling procedures on the testbed and present statistical results by 1040 concurrent users testing to evaluate the impact of overlay multicast network on the performance of the overall channel zapping time.