Hello Narad.
Most of the answers to these questions can be found in the lessons themselves. For now I’ll try to briefly answer them here.
Q1: This is the port priority and port number. A combination used to determine which port will be blocked in the event there are two or more links between two switches. The Prio is the priority set by default to 128, and it is 8 bits and the Nbr is a number that is assigned to this port, and this is another 8 bits. Together they represent the priority of the port. More about this at the end of the Spanning Tree Cost Calculation lesson.
Q2: Take a look at this post.
Q3 and Q4: Source mac address is the mac of the interface that sends out the BPDU ( if the interface has a mac address, if not, it will use one mac address reserved for the system use for protocol packets like BPDU in STP). The destination address is the multicast address reserved for STP 01-80-c2-00-00-00.
Q5: MACs for SVIs are assigned depending upon the platform. Some use the same MAC address for all, while others will use one from a pool of MAC addresses made available to the device. These are preconfigured or hardcoded in the device from the factory.
Q6: By default, BPDUs can be received on blocked ports.
Q7: This is described in detail in the Introduction to Spanning Tree lesson.
Q8: BPDUs are sent to directly connected neighbors. The neighbors will then relay the BPDUs down the STP tree until all switches receive the BPDUs.
Q9: I’m not sure I understand the question.
Q10: Convergence is described in the Introduction to Spanning Tree lesson.
Q11: Reconvergence will take place in the same way for both cases.
Q12: I’m not sure I understand the question.
I hope this has been helpful!
Laz