December 16, 2020 by eklose
In the example, the root switch sends the proposal. Switch A has its P1 switch port in the stated rejection state and forwards a proposal to BPDU. The circuit breaker`s BPDU is higher than the A switch. Therefore, Switch A is immediately moved to reject all non-angular port in order to avoid a 2-loop layer. 1.) The proposal/agreement process between S4 and S2 should be in the opposite direction. At present, it has been shown that S2 sends a proposal to S4 and S4 to respond with an agreement. It`s not true. A proposal can only be sent from a designated port in rejection or learning, as described in the Cisco “Understanding Rapid Spanning Tree Protocol” document on 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. When a switch receives a BPDU that fixes a bit of proposal on its root port, all non-Edge ports are put in a state of rejection…
This process is called Sync. A sync switch is isolated from the network, so the loops cannot be run by the network. 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? For the next downstream switch, the upper BPDU is transferred to the designated and recurrent states of its non-rejectionants, completing the proposal/agreement process. “When 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 sends. Switch A then sends its BPDU proposal down with the root switch IDB, which is the IDB of Switch A. – Proposal, SWA sends its higher BPDU to SWB, whose portages begin to be discarded. SWB concludes that SWB`s SWA port is the base port and refers an agreement to SWA. This starts the sync process, in which all non-Edge ports are blocked. 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.