A network administrator is configuring Rapid PVST+ on Switch-A within an enterprise switched topology. Switch-A links to Switch-B and Switch-C over 802.1Q trunk connections carrying multiple VLANs. The administrator executes the command `spanning-tree vlan 20 priority 24576` on Switch-A.
Which two statements correctly describe the resulting Rapid PVST+ operation and configuration characteristics on Switch-A for VLAN 20? (Select two.)
- Switch-A calculates its effective Bridge Priority for VLAN 20 as 24596 by adding the 12-bit System ID Extension value of 20 to the configured base priority of 24576.Cevap
- Rapid PVST+ sends BPDUs for VLAN 20 using the IEEE 802.1w structure tagged with a Cisco PVST+ SNAP header destined to multicast MAC address 01-00-0C-CC-CC-CD.Cevap
- CSwitch-A sets its total Bridge Priority for VLAN 20 to exactly 24576 because the System ID Extension field is omitted when Rapid PVST+ is explicitly configured.
- DConfiguring `spanning-tree portfast trunk` on the trunk interfaces connecting Switch-A to Switch-B and Switch-C optimizes Rapid PVST+ convergence without any risk of Layer 2 loops.
Cevap
The correct statements are that Switch-A calculates its effective Bridge Priority for VLAN 20 as 24596 () due to the System ID Extension, and that Rapid PVST+ sends BPDUs for VLAN 20 using 802.1w payloads encapsulated in Cisco PVST+ SNAP frames destined to 01-00-0C-CC-CC-CD.
The correct statements recognize that Rapid PVST+ automatically adds the 12-bit VLAN ID (20) to the base priority setting (24576) to form an effective Bridge Priority of 24596, and that Rapid PVST+ encapsulates 802.1w BPDUs into Cisco-specific SNAP frames destined for multicast MAC 01-00-0C-CC-CC-CD.
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Anahtar Kavram
Rapid PVST+ Bridge ID construction and per-VLAN BPDU frame encapsulation rules