Image the followign scenario
Switch 1 Managed (root)
Switch 2 Managed
Switch 3 Unmanaged
They are connected as follows:
Switch 1 <-> Switch 3
Switch 2 <-> Switch 3
Switch 1 <-> Switch 2
Switch 3 uplinked to internet
Device A connected to switch 2
What path does traffic from the internet take to get to the end devices? Is this coordinated between the two switches if so how?
Example:
Internet packet -> Unamanged Switch3 -> Switch 2 -> Device A?
Or
Internet packet -> Unamanged Switch3 -> Switch 1 -> Switch 2 -> Device A?
Remember that switch 3 is unmanaged and has no understanding of root priorities etc.