On the connection between S4 and S2, the F0/2 of the S4 is the designated port, while the Fa0/2 of the S2 is the root port, so the S2 should not send suggestions for this link. The right sequence of events is therefore that the S4 sends a proposal to the S2 and responds with an agreement on S4 after blocking all its non-edge ports. ”If a designated port is in a state of rejection or learning (and only in this case), it fixes the bit of proposal on the BPDUs it issues.” If an alternative P2 port, a specific P3 redirect port and an Edgeport P4 are present on Switch 1, P2 and P4 already meet one of the criteria. To be synchronized, Switch 1 must block the P3 port and give it the pier`s attribution status. When all ports are synced, Switch 1 can remove the blocking from the newly selected P1 port and respond to the strain by sending a message of agreement. This post is a copy of the BPDU proposal with the bit of agreement instead of the proposal bit. This copy ensures that Port P0 knows exactly which proposal corresponds to the agreement to which it corresponds. Switch A then sends its BPDU proposal with the IDB of the upper root switch to the IDB of Switch A. The explanation is great. I have only one doubt, will the root bridge be chosen before the procedure of seizing the hand of the proposal/agreement? If so, why is the BPDU proposal called a superior BPDU? The port of SWB to SWA is the base port and refers an agreement to SWA. This will start the synchronization process in which SWB will put all its ports in a state of rejection and send its own BPDU proposal to its neighbours downstream, if it receives a response from its neighbours downstream, it will put its base port in transfer status and send a BPDU agreement to SWA, set at 1, and the proposal is set at 0.
SWA ports will switch to redirection. Switch A reacts to the root switch with a transmission agreement. Both Switch ports move quickly to the redirect state with the certainty that there will be no layer 2 loops. 2.) Unlike animation, the proposal/agreement process between S2 and S3 does not take place at all. It is true that S2 can send a proposal to S3. However, S3 and S2 have already chosen another root port, and the arrival of BPDU on both sides will not change this selection. This means that the connection between S2 and S3 must be blocked, otherwise a loop would be formed to cross these two switches. On the other hand, a proposal/agreement procedure is used to quickly establish a link to a transit state. Therefore, even if s2 or S3 sends a proposal to its neighbor, no agreement can be sent, because the connection between S2 and S3 must remain blocked. – After the reciprocal exchange of BPDUs, which ultimately contain suggestions, each switch will be aware that the connection must remain blocked, because the base port on both switches will not be changed.