Lab 12: Disabling Auto-negotiation of Trunking

Lab Objective:

The objective of this lab exercise is for you to learn and understand how to turn off the auto-negotiation of a trunk link.

Lab Purpose:

Switch interfaces are set to automatically attempt to create a trunk link when connected to another switch. You need to know how to disable this behavior. Note that this behavior varies depending on the switch model.

Certification Level:

This lab is suitable for the CCENT certification exam preparation.

Lab Difficulty:

This lab has a difficulty rating of 5/10.

Readiness Assessment:

When you are ready for your certification exam, you should complete this lab in no more than 15 minutes.

Lab Topology:

Please use the following topology to complete this lab exercise:

Task 1:

In preparation for the configuration, configure a hostname on Sw1 as well as Sw2.

Task 2:

Configure Sw1 so that auto-negotiation of trunking is disabled. Set the port to manually trunk.

Task 3:

Verify your configuration with the appropriate show commands.

Configuration and Verification

Task 1:

For reference information on configuring hostnames, please refer to earlier labs.

Task 2:

 Sw1#show interface fast0/1 switchport 
Name: Fa0/1 
Switchport: Enabled 
Administrative Mode: dynamic auto 
Operational Mode: down 
Administrative Trunking Encapsulation: dot1q 
Operational Trunking Encapsulation: native 
Negotiation of Trunking: On 
Access Mode VLAN: 1 (default) 
Trunking Native Mode VLAN: 1 (default) 

Sw1(config)#int fast0/1 
Sw1(config-if)#switchport nonegotiate 
Command rejected: Conflict between ‘nonegotiate’ and ‘dynamic’ status. 
Sw1(config-if)#switchport mode trunk 
Sw1(config-if)#switchport nonegotiate 
Sw1(config-if)#end

Task 3:

NOTE: As you can see above, the interface cannot be left to dynamically become a trunk or access port if you want to disable auto-negotiation of trunking.

Sw1#show int fast0/1 switchport 
Name: Fa0/1 
Switchport: Enabled 
Administrative Mode: trunk 
Operational Mode: down
Administrative Trunking Encapsulation: dot1q 
Operational Trunking Encapsulation: dot1q 
Negotiation of Trunking: Off 
Access Mode VLAN: 1 (default) 
Trunking Native Mode VLAN: 1 (default) 
Voice VLAN: none

 


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