Current research on multicast benchmarking has focused primarily on measuring the performance capabilities of multicast forwarding devices without thoroughly addressing the impact routing protocols may have on the device. We provide a performance metrics taxonomy for multicast routing protocols to augment current work. These metrics are based upon the activities that occur during the lifetime of a multicast group, namely, the creation and termination of a group, the distribution of group communications, and the modification of group membership. These activities impact various multicast entities including hosts, routers, links, and the larger network supporting the group. Performance is further influenced by group characteristics including group size and the number of group senders. We discuss the dynamics of multicast systems, present a testing procedure for performance evaluation of multicast routing, and define metrics in three areas: latency, jitter, and bandwidth consumption.