The research and emulation on PIM-SM protocol

This paper summarizes the concept of multicast and the routing protocols, analyzes the principles of PIM-SM, and simulates PIM-SM in three scenarios on OPNET. As the simulation results show, in contrast to unicast, PIM-SM consumes less bandwidth, resulting in lower link occupancy rate. However, the higher end-to-end delay makes the switching from RPT to SPT long. Besides, when the recipient router locates between the sending router and RP, PIM-SM forwards redundant packets, and it is possible that the end-to-end delay of group members can be reduced. Furthermore, this paper explores the disadvantages of the standard PIM-SM and gives some improvements.