Refer to the exhibit. The UserA device fails to recede IPTV streaming traffic from the source. While debugging the issue a network engineer finds that routers RB and RC receive the multicast traffic…

Question

Exhibit

Options

• AConfigure ip pim ssm with ip igmp version 2 on interface GigabitEthernet 1/0.
• BRemove the ip pim ssm default configuration and replace it with ip pim rp-address 10.10.1.3.
• CChange ip igmp version 2 to ip igmp version 3 on interface GigabitEthernet 1/0.
• DConfigure ip pim bidir-enable in global mode and add ip pim rp-address 10.10.10.3.

• A
  3% (1)
• B
  14% (4)
• C
  79% (23)
• D
  3% (1)

Explanation

PIM Source-Specific Multicast (SSM) requires IGMPv3 on the host-facing router interfaces because only IGMPv3 supports the INCLUDE mode that specifies both the multicast group and the source address in join messages - the (S,G) join required by SSM. IGMPv2 only supports (*,G) joins (group-only, no source specification), which is incompatible with SSM operation. If RA has ip pim ssm default configured globally but ip igmp version 2 on GigabitEthernet 1/0 (the interface toward UserA), the router cannot process UserA's SSM join correctly - it cannot translate an IGMPv2 report into a PIM SSM (S,G) join, so UserA never receives the stream. Changing ip igmp version 2 to ip igmp version 3 on that interface (Option C) allows the router to correctly interpret UserA's source-specific join and forward it upstream as a PIM SSM (S,G) state, enabling the stream delivery. Option A is redundant since PIM SSM is already configured. Option B removes SSM and reverts to PIM-SM, which is an architectural change. Option D enables bidirectional PIM, which is a different multicast mode not needed here.

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