A network engineer is analyzing a Layer 2 topology operating with Cisco Rapid PVST+ for VLAN 10. Switch-1 is the Root Bridge. Switch-2 connects to Switch-1 via interface Gi0/1 and to Switch-3 via interface Gi0/2. Both links are full-duplex point-to-point connections. Currently, interface Gi0/1 on Switch-2 is the Root Port, and interface Gi0/2 on Switch-2 is selected as an Alternate port. Which two statements accurately describe the operational behavior and roles of interface Gi0/2 on Switch-2? (Select two.)
- Interface Gi0/2 operates in the Discarding port state while actively receiving BPDUs and maintaining a backup path to the Root Bridge.Answer
- If interface Gi0/1 loses connectivity, interface Gi0/2 can immediately transition to the Root Port role and move directly into the Forwarding state.Answer
- CInterface Gi0/2 is classified as a Backup port because it provides a redundant link connecting Switch-2 to Switch-3.
- DUpon failure of the primary root link, interface Gi0/2 must transition through 15 seconds of Listening and 15 seconds of Learning before forwarding frames.
Answer
Interface Gi0/2 operates in the Discarding port state while actively receiving BPDUs, and if interface Gi0/1 fails, interface Gi0/2 can immediately transition to the Root Port role and enter the Forwarding state.
In Rapid PVST+ (802.1w), an Alternate port provides a redundant path to the Root Bridge and remains in the Discarding state during normal operations. If the current Root Port fails, Rapid PVST+ allows the Alternate port to immediately assume the Root Port role and transition directly into the Forwarding state without undergoing timer-driven Listening and Learning delays.
Step-by-Step Solution
Key Concept
Rapid PVST+ Port Roles (Alternate vs Backup) and Fast Transition Convergence Mechanics