Hi, I’m learning the purpose of each BPDU field(also each option) to create my Anki flashcards, but there is an option in the Version ID(0x04 SPT BPDU) that i don’t find their purpose, please could you clarify in which situations that value is use?. I also verify your notes about BPDU fields, but it just mention for SPT.
A Version ID value of 4 corresponds to a Shortest Path Tree (SPT) BPDU. SPT BPDUs are used in the context of Shortest Path Bridging (SPB) which is defined in the IEEE 802.1aq standard. Such a BPDU is part of the operation of SPB to allow bridges to exchange network topology information and to construct multiple STPs, allowing SPB to achieve its primary advantage, which is to create a loop-free environment while avoiding the use of blocking links like more traditional STP protocols.
Strictly speaking, SPB is not really a part of the more traditional STP standards. The use of the BPDUs in its operation with the appropriate version number is somewhat unconventional, but there it is. For this reason, information about it is somewhat more scarce than for other protocols.
For more information about SBP, take a look at this NetworkLessons note on SPB.
I hope this has been helpful!