中文摘要：

在覆盖网络中为VoIP业务计算端到端路径时,需要保证该路径的时延小于150 ms;由于覆盖网络中反三角现象普遍存在,因此,为了保证VoIP业务时延要求,应用中继技术计算从源节点通过中继节点到目的节点的路径,取代端到端路径,成为覆盖网络提供VoIP业务的关键技术。基于已有中继技术存在的部署难、未考虑路径差异及结果不是最优等问题,提出基于路径优先度的VoIP中继选择算法,该算法首先提出路径优先度的概念,描述时延和默认IP路径的差异性,再基于路径优先度构建中继路由表,在中继路由表中挑选最优中继节点;提出基于路径优先度的两跳中继选择算法进一步减少转发时延。仿真证明所提算法能够减少VoIP业务的传输时延,提升VoIP业务的用户体验。

英文摘要：

When routing the end-to-end path in the overlay network for VoIP service, it is necessary to ensure the path delay less than 150 ms. Due to the triangle inequality variations existed generally in the overlay network, the current research focus on building a multi-path routing using relay node selection algorithms instead of the end-to-end path to guarantee the VoIP service delay requirements. But the existed relay algorithms have limitations, such as deployment difficult, ignoring the difference between the paths. A new algorithm-a path-priority based relay selection algorithm for VoIP was proposed. First, the concept of the path priority degrees was introduced to describe the reference delay and the difference with the default IP path. Then a relay table was built and the best node was selected from the table to route the path. The algorithm reduced the delay further through two-hop relay selection algorithm at last. Simulation results show that the proposed method can reduce the transmission delay of VoIP services and enhance the user experience of VoIP.