Receiver-Initiated Multicasting with Multiple QoS Constraints

In this report we present our work on a receiver-initiated approach called RIMQoS to support multicast with multiple QoS constraints and dynamic memberships. Assuming link-state information is available, a receiver computes a path to join the multicast tree rooted at the source. It then sends join request along the path to join the group. We first present the operation of our approach in an intra-domain setting with delay constraint. Then we introduce an algebraic formulation for multiple QoS constraints to show how to determine if QoS requirements for a new receiver can be satisfied at an intermediate node along the join path and how to adjust the tree without breaking QoS requirements for existing members if they are not. It attempts to minimize the cost of the tree by letting a node to join the tree via a low-cost path and may later switch to a higher-cost but more QoS stringent path when necessary. Our scheme builds multicast tree incrementally and thus supports fully dynamic memberships. It also supports of heterogeneous receivers seamlessly. Moreover, it can support any number of arbitrary QoS metrics without assuming any dependencies among them, if they satisfy some normal mathematical property. If implemented as a distributed routing protocol, our approach doesn’t require any node to have explicit knowledge of the multicast tree topology, thus it scales well for multicast of large group. Simulation studies have been carried out to study its behavior and compare its performance with other schemes. keywords: multicast, multicast routing, Quality of Service, multiple QoS constraints. This work is partially supported by grants from NASA and Cisco Systems.