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Zorluk: OrtaRapid PVST+ Spanning Tree Protocol Operations and Roles

A network engineer connects two Cisco Catalyst switches using a point-to-point GigabitEthernet link running Rapid PVST+. Place the steps of the Rapid PVST+ Proposal and Agreement handshaking process in the correct chronological order from first to last.

  1. 1The upstream switch sends a BPDU with the Proposal bit set out of its designated port toward the downstream switch.
  2. 2The downstream switch receives the proposal and initiates synchronization by placing all non-edge designated ports into the Discarding state.
  3. 3The downstream switch transmits a BPDU with the Agreement bit set back to the upstream switch.
  4. 4The upstream switch receives the agreement and immediately transitions its designated port to the Forwarding state.

Cevap

The correct chronological sequence for the Rapid PVST+ Proposal-Agreement handshake is: 1) Upstream switch sends a Proposal BPDU, 2) Downstream switch puts non-edge designated ports into Discarding state (sync), 3) Downstream switch sends an Agreement BPDU, 4) Upstream switch immediately transitions its designated port to Forwarding.
Rapid PVST+ achieves rapid convergence on full-duplex point-to-point links via an explicit handshake. First, an upstream switch sends a Proposal BPDU. Second, the receiving downstream switch performs synchronization by forcing all non-edge designated ports into the Discarding state. Third, the downstream switch returns an Agreement BPDU. Finally, the upstream switch receives the Agreement and immediately transitions its designated port to Forwarding.

Adım Adım Çözüm

1
Initiate Handshake
The upstream switch transmits a configuration BPDU with the Proposal bit set on a point-to-point link.
Rapid PVST+ uses explicit handshaking on point-to-point links rather than waiting for 802.1D forward delay timers.
2
Perform Synchronization
The receiving (downstream) switch blocks all non-edge designated ports, putting them into the Discarding state.
Enforcing the synchronization (sync) state isolates the local switch topology to ensure no temporary switching loops are formed.
3
Send Agreement
The downstream switch sends a BPDU back with the Agreement bit set.
This confirms to the upstream neighbor that the downstream switch has isolated its local ports and accepted the proposal.
4
Transition to Forwarding
The upstream switch transitions its designated port directly to the Forwarding state.
Receiving an explicit Agreement allows immediate state transition without waiting for timer expiration.

Anahtar Kavram

Rapid PVST+ (802.1w) Proposal-Agreement Synchronization Process
Tahmini Süre:1m 30s
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