Multicast Traffic Replication Across a vPC Peer Link
Short answer
C The multicast traffic is replicated to the ports that joined a given multicast group and the peer link.
Question
Key Takeaways
vPC multicast uses the SVI/PIM and the peer-link as a multicast forwarding path. The active forwarding vPC peer device sends a copy out the vPC member port and a copy out the peer-link; the peer device forwards only to interested ports.
On a vPC pair, multicast (PIM) traffic from the source tree is forwarded out vPC member ports toward receivers and also copied across the vPC peer-link so the peer switch can serve its locally attached receivers; orphan ports with no interest drop it.
Common mistake: Believing multicast is NOT replicated to the peer-link. It is: the peer-link carries multicast to the peer so it can serve its own receivers; without that, receivers behind the secondary peer would starve.
Expert Analysis
Why the Answer Is Correct
Multicast data flows down the source tree to the active forwarding vPC peer device. That device replicates the stream out the vPC member port connected to the access switch and out the vPC peer-link. The peer device, upon receiving it, forwards only to ports that joined the multicast group; it drops copies for ports with no interest.
Why the Other Options Are Wrong
A and D claim the traffic is NOT replicated to the peer-link or group ports, which contradicts vPC multicast forwarding behavior. B carries identical text to C in the exhibit; per community consensus C is the selected correct option describing replication to both group ports and the peer link.
Community Comment Notes
Community: "Multicast data traffic flows down the source tree to active forwarding vPC peer device. vPC peer device 1 sends a copy out the vPC member port... One copy is sent out of vPC peer-link." Votes C 100.
Official Reference
This link opens the official vendor documentation in a new tab.
Community Votes
100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 6 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 6
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asd248402 👍 3 Answered CMulticast data traffic flows down the source tree to active forwarding vPC peer device. vPC peer device 1 (7K1) sends a copy of the multicast traffic out of the vPC member port connected to access switch. One another copy is sent out of vPC peer-link. As there is no single-attached device (or orphan port) interested by this multicast traffic on the other side, vPC peer device 2 (7K2) will drop the multicast traffic
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msalamehi 👍 2 Answered CAgree C is correct 100%
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luisam 👍 2Answer A
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Eduardo7v 👍 1OPtion C confirmed by CHATGPT
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wickkkkkkkkkkkkkkkkkk 👍 1BBBBBBBBBBBBBBBBBBBBBBBBB
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crooks_1988 👍 1Agree it is C
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