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Zorluk: OrtaRapid PVST+ Spanning Tree Protocol Operations and Roles

A network administrator configures a Cisco Catalyst switch running Rapid PVST+ by setting the base bridge priority for VLAN 25 to 1638416384 using the command `spanning-tree vlan 25 priority 16384`. Which value represents the exact priority component of the Bridge Identifier (BID) transmitted in BPDUs by this switch for VLAN 25?

  1. 1640916409Cevap
  2. B
    1638416384
  3. C
    1641016410
  4. D
    1635916359

Cevap

The correct priority component in the BID is 1640916409, calculated by adding the configured base priority of 1638416384 and the VLAN ID extension of 2525.
Rapid PVST+ implements 802.1t System ID Extension, dividing the traditional 16-bit priority field into a 4-bit Priority field (multiples of 4096) and a 12-bit System ID Extension containing the VLAN ID. When a switch transmits BPDUs for VLAN 25 with a base priority of 1638416384, the actual BID priority header value becomes 16384+25=1640916384 + 25 = 16409.

Adım Adım Çözüm

1
Identify the base priority and System ID Extension configured for the VLAN.
Base Priority = 1638416384, System ID Extension = 2525 (VLAN 25).
Rapid PVST+ uses the 12-bit System ID Extension to embed the VLAN ID into the Bridge Identifier structure.
2
Calculate the total BID priority value.
16384+25=1640916384 + 25 = 16409.
The total bridge priority field encoded into BPDUs is the sum of the 4-bit base priority prefix and the 12-bit VLAN identifier.

Anahtar Kavram

Rapid PVST+ System ID Extension and Bridge Identifier (BID) Calculation
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Konular

Rapid PVST+ Spanning Tree Protocol Operations and Roles

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