In a plain PIM snooping configuration, VPLS PE routers only snoop; PIM messages are generated on their own. Join/prune suppression must be disabled on CE routers.
When plain PIM snooping is configured, if a VPLS PE router detects a condition where join/prune suppression is not disabled on one or more CE routers, the PE router puts PIM snooping into the PIM proxy state. A trap is generated that reports the condition to the operator and is logged to the syslog. If the condition changes, for example, join/prune suppression is disabled on CE routers, the PE reverts to the plain PIM snooping state. A trap is generated and is logged to the syslog.