This action sends an SNMP trap message to the trap server, with a configurable ID and message string, when the rule is triggered. The message is sent periodically with interval period seconds. If period is 0, or if this optional parameter is not present, the message is sent only once when the rule is triggered. The interval must be a multiple of the rule sampling/evaluation interval, or the value will be rounded down to a multiple of the rule sampling/evaluation interval.