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Difficulty: MediumInterswitch Connectivity and Trunking (802.1Q)

A network engineer needs to configure a static IEEE 802.1Q trunk link on Cisco switch interface GigabitEthernet0/1, disable Dynamic Trunking Protocol (DTP) negotiation, and configure VLAN 99 as the untagged native VLAN. Place the following CLI configuration commands in the correct logical execution sequence from first to last.

  1. 1interface GigabitEthernet0/1
  2. 2switchport trunk encapsulation dot1q
  3. 3switchport mode trunk
  4. 4switchport nonegotiate
  5. 5switchport trunk native vlan 99

Answer

The correct execution order is: interface GigabitEthernet0/1, switchport trunk encapsulation dot1q, switchport mode trunk, switchport nonegotiate, and switchport trunk native vlan 99.
The CLI commands follow strict Cisco IOS configuration order dependencies. First, access the interface mode with 'interface GigabitEthernet0/1'. Second, set encapsulation using 'switchport trunk encapsulation dot1q'. Third, enable static trunking with 'switchport mode trunk'. Fourth, disable DTP frames using 'switchport nonegotiate' (which fails if the port is in dynamic DTP mode). Finally, assign untagged traffic processing using 'switchport trunk native vlan 99'.

Step-by-Step Solution

1
Enter interface configuration mode
Context changes to Switch(config-if)# for GigabitEthernet0/1
CLI commands affecting a specific port require entering that interface context first.
2
Set trunk encapsulation to IEEE 802.1Q
Interface protocol encapsulation set to dot1q
Cisco IOS platforms supporting both ISL and 802.1Q require explicit encapsulation specification before changing mode to trunk.
3
Configure operational mode to static trunk
Interface changes state to unconditional trunking mode
Establishes trunk operational state.
4
Disable Dynamic Trunking Protocol negotiation
DTP frame transmission is stopped on the interface
The 'switchport nonegotiate' command is rejected by Cisco IOS if the interface remains in dynamic auto or dynamic desirable mode.
5
Modify the native VLAN identifier
VLAN 99 becomes the untagged VLAN for IEEE 802.1Q traffic
Applies non-default native VLAN parameter to prevent native VLAN mismatch security issues.

Key Concept

IEEE 802.1Q Trunk Configuration and DTP Suppression Sequence
Estimated Time:1m 30s
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Topics

Interswitch Connectivity and Trunking (802.1Q)

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