A network administrator is configuring Rapid PVST+ on a Cisco Catalyst switch. The adminis… — Cisco CCNA

A network administrator is configuring Rapid PVST+ on a Cisco Catalyst switch. The administrator wants the switch to achieve a total Bridge Identifier (BID) priority of $16484$ for VLAN $100$ . Which Cisco IOS command correctly sets the base priority to accomplish this target total priority?

spanning-tree vlan 100 priority 16384Answer
B
spanning-tree vlan 100 priority 16484
C
spanning-tree vlan 100 priority 15000
D
spanning-tree vlan 100 priority 16384 portfast

Answer

The command 'spanning-tree vlan 100 priority 16384' correctly sets the base bridge priority.

In Rapid PVST+, the total Bridge Identifier (BID) priority is the sum of the base bridge priority and the System ID Extension (which equals the VLAN ID). To achieve a total priority of

16484

in VLAN

100

, the base priority must be configured as

16384

(

16384 + 100 = 16484

). Base priorities must be configured in multiples of

4096

Step-by-Step Solution

Calculate the required base bridge priority

Base Priority = Total BID Priority - System ID Extension (VLAN ID) =

16484 - 100 = 16384

Rapid PVST+ automatically appends the VLAN ID (System ID Extension) to the base bridge priority to form the final BID priority.

Verify priority increment rules

16384 = 4096 \times 4

, which is a valid priority increment

Cisco IOS requires the base STP priority value to be configured in steps of 4096.

Formulate the correct Cisco IOS configuration syntax

spanning-tree vlan 100 priority 16384

The command syntax specifies the base priority without manually adding the VLAN ID.

Key Concept

Rapid PVST+ System ID Extension and Base Priority Increments

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