INE Lab 1 Section 1.6

1.6  Disabling DTP Negotiation 
•  Disable Dynamic Trunking Protocol on the trunk links of SW1. 
•  Verify that trunking is still occurring between SW1 & SW2, SW1 & SW3, 
and SW1 & SW4 without the use of DTP. 

Still very confusing about the DTP mode. Google search and found the DTP relationship table. Below is the mode that able to form the Trunking Mode.

switchport mode access -  This command puts the interface (access port) into permanent nontrunking mode.  The interface will generate DTP frames, negotiating with the neighboring interface to convert the link into a nontrunk link. The interface becomes a nontrunk interface even if the neighboring interface does not agree to the change.

switchport mode dynamic desirable  - This command makes the interface actively attempt to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode. This is the default mode for all Ethernet interfaces.  If the neighboring interface is set to the access or non-negotiate mode, the link will become a non-trunking link.


switchport mode dynamic auto – This command makes the interface willing to convert the link to a trunk link if  the neighboring interface is set to trunk or desirable mode.  Otherwise, the link will become a non-trunking link.

switchport mode trunk – This command puts the interface into permanent trunking mode and negotiates to
convert the link into a trunk link. The interface becomes a trunk interface even if the neighboring interface does not agree to the change.

switchport nonegotiate – Prevents the interface from generating DTP frames. You can use this command only when the interface switchport mode is access or trunk. You must manually configure the neighboring interface as a trunk interface to establish a trunk link, otherwise the link will be a non-trunking link.