Sets the mechanism to be used for processing the leave messages in the down stream interface. When this object is set to 'explicitHostTrack', then the leave messages are processed using the explicit host tracking mechanism. When this object is set to 'fastLeave', the leave messages are processed by the fast leave mechanism. When this object is set to 'normalLeave', for every leave message received, a group or group specific query is sent on the interface. This object can be configured only when fsSnoopInstanceGlobalLeaveConfigLevel is set to portbased. This object is applicable only for processing the igmp v2 leave messages. For igmpv3 reports, the explicit host tracking functionality is always performed for tracking the source registrations and it cannot be disabled (i.e.) configuration using this object has no effect.