Imagine an access switch dual homed to a vPC domain. One link to each switch in the vPC domain. If an STP BPDU is received at the access switch from one uplink, will it forward it out the other uplink? I would say no, otherwise the basic forwarding rules for a LAG will be violated. Ports in a LAG are treated as a single construct. So, a broadcast or multicast frame received on one LAG port will NOT be sent out the other because those 2 physical ports are viewed as ONE logical port and frames are never flooded out the same port from which they were received.
No?
