以IMS为核心的NGN网络己被认为是适应未来固定网与移动网融合的网络架构。要实现IMS跨网络的QOS保证,需要域间、上下层的相互协作。文中分析了IMS QoS机制,指出了在资源协商、资源预留以及资源保证方面SIP协议的不足,提出了一种基于SIP扩展实现多域间QoS的方案,分析了该方案所带来的在信令流程中减少信令负荷等方面的改进,并给出了具体实现方案。 The NGN network that takes IMS as the core has been considered as the network architecture that adapts to the convergence of the fixed network and the mobile network in the future. To achieve QOS assurance across IMS networks, inter-domain and upper-lower layer collaboration is required. This paper analyzes IMS QoS mechanism, points out the shortages of SIP protocol in terms of resource negotiation, resource reservation and resource guarantee, proposes a scheme of implementing inter-domain QoS based on SIP extension, So that the process to reduce the signaling load and other improvements, and gives the specific implementation.