On the stability of multicast flow aggregation in IP over optical network for IPTV delivery
支持IPTV传送的IP over optical网络中组播流汇聚的稳定性研究

罗萱 Xuan Luo, 金耀辉 Yaohui Jin, 曾庆济 Qingji Zeng, 孙卫强 Weiqiang Sun, 郭薇 Wei Guo, 胡卫生 Weisheng Hu
2008 Chinese Optics Letters (COL)  
The stable multicast flow aggregation (MFA) problem in internet protocol (IP) over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access routers attached to the optical network, in which each head end can provide a set of programs (IP multicasting flows) and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of
more » ... the requests of access routers changed dynamically. We introduce a program correlation matrix to describe the preference of end users' requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first (MCPF), is presented and compared with the extended least tree first (ELTF) algorithm which is topologyaware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage. Internet protocol television (IPTV), a promising revenue generating application in the telcos' triple-play service portfolio, has been trialed and deployed by various operators and companies [1, 2] . 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. Since customers are used to viewing television programs without any appreciable jitter or delay, end-to-end quality of service (QoS) control is a must in the video service deployment. However, it is difficult to implement large-scale multicasting with hard QoS guarantees in packet-switched IP network due to its essential best-effort nature. To meet the stringent QoS and availability requirements of multimedia service, a novel hybrid packet/circuit multicasting network model has been proposed [3] . This hierarchical multicasting architecture, with optical multicasting (always implemented by the use of light-tree) in the core and IP multicasting at the edge, can not only greatly simplify QoS provisioning and traffic engineering but also preserve compatibility with the existing IP access networks. In China, 3TNet, a pioneering research initiative adopting the hybrid packet/circuit multicasting for large-scale IPTV-oriented streaming media delivery, has been carried out in Yangtze River Delta [4] . Generally, the bandwidth of one light-tree is much higher than that required by one single IP multicasting flow. Bandwidth efficiency can be remarkably increased by carefully aggregating multiple IP flows into one single light-tree, which is defined as multicast flow aggregation (MFA) problem [5] . The MFA problem, different from multicast grooming problem [6] and aggregated multicast problem [7] , has been proven as NP-complete. A heuristic algorithm, named least tree first (LTF), has been proposed to minimize the resource usage for the large-scale network [5] . However, if we use the LTF algorithm in the dynamical scenario, we find that both the combination
doi:10.3788/col20080608.0553 fatcat:c6tqzri3x5aqldzfggtnj4cq54