Multicast routing and its QoS extension: Problems, algorithms, and protocols

Multicast services have been increasingly used by various continuous media applications. The QoS requirements of their continuous media applications p rompt the necessity for QoS-driven, constraint-based multicast routing. Thi s article provides a comprehensive overview of existing multicast routing a lgorithms, protocols, and their QoS extension. In particular, we classify m ulticast routing problems according to their optimization functions and per formance constraints, present basic routing algorithms in each problem clas s, and discuss their strengths and weaknesses. We also categorize existing multicast routing protocols, outline the issues and challenges in providing QoS in multicast routing, and point out possible future research direction s.