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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. The proposal/agreement mechanism only applies to P2P duplex connections between two switching devices. If the proposal/agreement fails, a designated port is selected based on two forward delay intervals, such as the designated port choice in STP mode. I explained it one after another, because it would be very chaotic to explain PoV of all the switches at once. When a new connection is created between Root and Switch 1, both ports will be transferred to a particular block state until they receive a BPDU of their equivalent. The proposal bit on BPDUs is only fixed and sent if a designated port is in a state of rejection or learning. This process occurs for port P0 of the main deck. As Switch 1 receives superior information, Switch 1 immediately knows that Port P1 is the new root port.

Switch 1 then ensures that all ports are synchronized with this new information. – 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. Therefore, after replacing the BPDUs on the S2-S3 connection, it will be immediately clear which port is the designated port and what is the alternative port on that connection. The alternative port no longer sends BPDUs and remains in a state of rejection, while the designated port slowly moves from rejection to “Learn” to redirect state. However, no agreement is sent from the two switches and no other non-edge port is blocked due to the receipt of a proposal. In the event that the proposal and the agreement process fail RSTP must rely on the old cars used in the regular stPs. There is a timer called FdWhile, which is identical to the forward deceleration and is 15s by default. After trying to send proposals for 15zus, he will begin to bring the port by releases, learning, and then for transmission.

I simulated this scenario below by blocking the BPDUs between SW3 and SW4. If SW1 has obtained the BPDU agreement, it can start redirecting it to its intended port.