What does an FHR do when an attached source becomes active and there are no interested receivers?

What does an FHR do when an attached source becomes active and there are no interested receivers?

• It unicasts register messages to the RP and stops after a register stop from the RP.
• It unicasts encapsulated register messages to the RP and stops after a register stop from the RP.
• It waits for the RP to send register message indicating that there are interested receivers.
• It multicasts encapsulated register messages to the RP and stops after a register stop from the RP.
• It unicasts encapsulated register messages to the RP until there are interested receivers.

Explanation: When there is an active source attached to the FHR, the FHR encapsulates the multicast data from the source in a special PIM-SM message called the register message and unicasts that data to the RP by using a unidirectional PIM tunnel. When the RP receives the register message, it decapsulates the multicast data packet inside the register message, and if there is no active shared tree because there are no interested receivers, the RP sends a register stop message to the FHR, instructing it to stop sending the register messages.

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