Multicast routing in dense and sparse modes: simulation study of tradeoffs and dynamics

PIM Protocol Independent Multicast is capable of sup porting sparse mode SM and dense mode DM op erations In sparse mode PIM can use shared trees RPT or shortest path trees SPT to deliver data pack ets One frequently asked questions was how to decide when to use sparse mode and when to use dense mode What is the criteria Another unanswered question was whether packets can be lost when receivers switch from RPT to SPT This paper reports a study of the overhead tradeo s between dense mode operations and sparse mode operations the behaviors of PIM when receivers transitioning from RPT to SPT One important result presented is the cross over point of sparse mode and dense mode overheads which gives a hint for selecting protocol modes according to the group density metric