It is pointed out that there exist questions on applying MPLS to the building of the MAN by analyzing the advantages, existing problems and algorithms on diff-services of MPLS.

• 通过分析MPLS技术的优势、现存问题和MPLS支持区分服务的具体算法，从多方面说明了多协议标记交换MPLS技术在构建城域网中存在的问题。