Consider the IEEE 802.1D (first revision) Spanning Tree Protocol. I have read a lot of articles and forum entries about STP convergence. Often I do find contradictions about the convergence mechanics. Some people state that convergence follows this schematics:
- Root bridge election
- Root port selection
- Designated ports selection
- Non-designated port selection
Others state that each port cycles through 4 states (Blocking, Listening, Learning, Forwarding). I don't understand how they each connect and how the root bridge election for example takes part in those 4 states. For me, both "models" don't go along with each other, but each part of both of them are neccessary to make STP work in my opinion. The problem, however, is not understanding how each state behaves in terms of packet discarding/MAC learning/etc.. The problem is understanding how it all works together.
Unfortunately, the IEEE standard doesn't help with unterstanding, yet it makes things harder to grasp for me.
Edit: my question was marked as a duplicate to Spanning tree - port roles and status during root bridge election. First of all, the answer doesn't explain the whole convergence process. Furthermore, I don't understand how a bridge decides that it is not connected to another bridge performing STP. How long will it until it decides it is alone and probably the root bridge? When does it stop propagating this?
Edit2: after understanding that the port role is decided when a better BPDU in terms of SPT tie breaking mechanism is received, I still don't get how a switch decides which port is designated.