Abstract: IMS-based IPTV not only requires higher performance of Service Control Function (SCF) server, but also brings many restrictions to the traditional load balancing technologies due to a Session Initiation Protocol (SIP) with double integrity requirements of transaction and dialog. Combining service trigger mechanism in IP Multimedia Subsystem (IMS) and the session statistical characteristic of the IPTV services, a multi-level load balancing mechanism with the features of service differentiation among clusters and server-load awareness within every cluster was discussed to solve the performance bottleneck in IPTV SCF, and a method differentiating SIP transaction priorities and a lightly random scheduling algorithm based on a dynamic weight were proposed. Finally, the technological feasibility was verified in IPTV prototype, and the detailed solution was depicted.

Key words: IP Multimedia Subsystem (IMS), Service Control Function (SCF), load balancing, session-aware, behavior statistic

摘要： 基于IP多媒体子系统(IMS)的IPTV引入集中式SIP会话管理机制，除对业务控制功能(SCF)服务器提出更高的响应性能要求，而且由于SIP的事务和对话双重完整性，对传统负载均衡技术也带来诸多限制。针对SCF的性能瓶颈，结合IMS的业务触发过程和IPTV业务的会话统计特性，探讨了集群间区分业务和集群内对后台服务器负载感知的多级负载均衡机制，并提出基于SIP事务优先级的轻量级动态权值随机调度算法。最后在IPTV原型系统中验证了该负载均衡机制的技术可行性，并给出具体实验方案。

关键词: IP多媒体子系统, 业务控制功能, 负载均衡, 会话感知, 行为统计