Refer to the exhibit. R21 is a multicast source sending multicast traffic 224.1.1.1 to R23, with RP22 serving as the rendezvous point inside AS65222. A network engineer noticed that when R21 goes…

Question

Exhibit

Options

• ABlock service groups 224.0.1.39 and 224.0.1.40 between the two autonomous systems.
• BDisable PIM parse mode between RP11 and RP22 in the two autonomous systems.
• CAdvertise RP2 with a high local preference in AS65222.
• DEnable passive interface under EIGRP between the two autonomous systems.

• A
  75% (45)
• B
  3% (2)
• C
  8% (5)
• D
  13% (8)

Explanation

This question involves Auto-RP, which is Cisco's proprietary mechanism for automatically distributing Rendezvous Point (RP) information in PIM Sparse Mode networks. Auto-RP uses two reserved multicast groups: 224.0.1.39 (cisco-rp-announce) for RP candidates to announce themselves to the mapping agent, and 224.0.1.40 (cisco-rp-discovery) for the mapping agent to distribute RP-to-group mappings to all PIM routers. The problem is that these Auto-RP service group messages are leaking between AS65111 and AS65222. When R21 (the source in AS65222) goes down, routers in AS65111 discover RP11 as a valid RP for group 224.1.1.1 because RP11's Auto-RP announcements are crossing the AS boundary. Blocking 224.0.1.39 and 224.0.1.40 at the inter-AS boundary prevents RP information from leaking between autonomous systems, ensuring each AS uses only its own designated RP. Option B is incorrect because 'PIM parse mode' is not a standard feature for inter-AS RP control. Option C would affect BGP route preference but not RP selection. Option D (EIGRP passive interface) is unrelated to multicast RP discovery.

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