Refer to the exhibit. What happens to the broadcast traffic when it reaches aggregation switches?

A. Agg-2 switch receives broadcast packets and stops forwarding to the peer link on Agg-1 switch.

B. Agg-1 switch prevents broadcast packets received on the vPC peer link from exiting the switch on ports Eth2/4 and Eth2/5.

C. Agg-1 and Agg-2 switches receive broadcast packets and does not forward them to the peer link or the port channel.

D. Only Agg-1 switch receives broadcast packets and does not forward to the peer link on Agg-2 switch.








 

Suggested Answer: B

Duplicate Frames Prevention in vPC
One of the most important forwarding rules for vPC is that a frame that enters the vPC peer switch from the peer link cannot exit the switch from a vPC member port.Figure shows switch-es 3 and 4 connected to 5k01 and 5k02 with vPCs Po51 and Po52. If one of the hosts connected to switch 4 sends either an unknown unicast or a broadcast, this traffic may get hashed to port eth2/2 on PortChannel 52. 5k02 receives the broadcast and needs to forward it to the peer link for the potential orphan ports on 5k01 to receive it.
Upon receiving the broadcast, 5k01 detects that this frame is coming from the vPC peer link. Therefore, it does not forward it to port 2/9 or 2/10; if it did, a duplicate frame on switch 3 or 4, respectively, would be created.
If a host on switch 4 sends a broadcast, 5k02 will correctly forward it to Po51 on port 2/9 and place it on the peer link. 5k01 will prevent this broadcast frame from exiting onto port 2/9 or 2/10 because this frame entered 5k01 from a vPC peer link. Should eth2/2 on switch 3 go down, port 2/9 on 5k01 would become an orphan port and as a result will receive traffic that traverses the peer link.
 
Reference:
https://www.cciein8weeks.com/courses/ccie-dc-400-151-v2-1-exam-cert-guide-3rd-edition/297/

This question is in 350-601 DCCOR exam 
For getting CCNP Data Center Certificate


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