Rerouting of multicast connections with quality-of-service constraints

In the long-term operation of any real network that supplies multicast capability, the fixed routing algorithms provide solutions that are only temporarily efficient, due to the dynamic nature of the network environments. We study the problem of re-routing multicast traffic that meets the quality-of-service requirements of real-time, distributed multimedia applications. In particular, we assume that multicast communication depends on bounded delays along the paths from the source to each destination. We present a technique for modifying a multicast tree under an end-to-end delay constraint that is cost-efficient and which flexibly manages load in the network. The constrained Steiner tree improvement technique in directed graphs makes use of a strategy for providing an end-to-end delay guarantee by apportioning it locally for each link. It has been purposely designed to meet the requirements for distributed implementation in asymmetric networks.