What is the purpose of an RP in PIM?

Question

Exhibit

Options

• Asend join messages toward a multicast source SPT
• Bensure the shortest path from the multicast source to the receiver.
• Creceive IGMP joins from multicast receivers.
• Dsecure the communication channel between the multicast sender and receiver.

• A
  90% (37)
• B
  2% (1)
• C
  5% (2)
• D
  2% (1)

Explanation

PIM Rendezvous Point (RP) Explained

In PIM Sparse Mode, the Rendezvous Point (RP) serves as a meeting place where multicast sources and receivers initially connect, and its core function is to send Join messages toward the source, building a Shared Distribution Tree (RPT) that connects receivers to the multicast group - making Option A correct.

Why the distractors are wrong:

• Option B is incorrect because the RP actually creates a shared tree, not the shortest path; shortest-path trees (SPTs) are built after traffic switches away from the RP once a threshold is met.
• Option C is incorrect because IGMP joins are received by the designated router (DR) on the receiver's local segment, not the RP - the RP receives PIM Join messages, not IGMP messages.
• Option D is incorrect because the RP has no security function; it is purely a traffic distribution and tree-building mechanism.

Memory Tip: Think of the RP as a postal sorting hub - it doesn't secure or speed up delivery, it simply serves as the central point where mail (multicast traffic) is routed toward the source and distributed to receivers until a more direct route is established.

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