在以IP为基础的网络中，IP网络上传送语音(VoIP)成为新一代语音系统的代表，但其业务质量因由IP网络承载而受到限制。多协议标签交换(MPLS)是当前被普遍看好的高速骨干网络技术，通过MPLS，第三层的路由可以得到第二层技术的很好补充，以保证端到端的服务质量(QoS)。将MPLS的QoS特性与区分服务(DiffServ)相结合，可实现更优化的网络业务QoS。

In IP-based networks, VoIP has become the representative technology of the next generation voice system, but its QoS is limited by the IP network capacity. Now MPLS is regarded as a most promising technology for high-speed backbone networks. By MPLS, layer 3 routing can be well complemented by layer 2 switching, which guarantees the point-to-point QoS. Network performance can be further optimized by the combination of DiffServ and QoS of MPLS.