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PIM Sparse Mode: Multicast Tree Building

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PIM Sparse Mode: efficient multicast for sparse receivers

IP multicast sends one stream that reaches many receivers — essential for live video, financial data feeds, and real-time telemetry. But unlike unicast (one path, one destination) or broadcast (all ports), multicast must build a delivery tree that covers exactly the receivers that want the stream.

PIM Sparse Mode (RFC 7761) builds these trees using a Rendezvous Point (RP) as a meeting point: receivers join a shared tree toward the RP, sources register with the RP, and then the network optionally optimizes to shortest-path trees per receiver.

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