I also dove back into STP, spanning tree protocol in the first video (of 4 for STP), in my computer based training courses.
BPDU's are transmitted every 2 seconds to multicast address 01-80-c2-00-00-00 in the types of:
- topology change notification (TCN) - change in network topology
- configuration - Used for STP calculations and the root bridge will originate these while the non-root bridges will forward them
(i.e. 32768:1f:23:45:67:89:90). Lowest BID wins STP root-bridge election.
Commands that I saw during this lesson:
show spanning-tree vlan [id]
(interface) spanning-tree cost [1-200000000] - does a cost adjustment for ALL vlans
(interface) spanning-tree vlan [id] cost [1-200000000] - changes for a vlan in pvstp
10 MBPS - 100
100MBPS - 19
1GBPS - 4
10 GBPS - 2