Dynamic Trunking Protocol (DTP)

Hi everyone, in this article, I will explain what DTP is and how it works.

DTP is a protocol that allows switch ports to be configured automatically.

In simple terms, if you change the mode of one port on a switch, the corresponding port on the connected switch will automatically adjust its mode. You can refer to the table below to see the possible mode combinations.

For example, if one port of a switch is dynamic auto and the port to which the other switch is connected is trunk, the ports will automatically switch to trunk mode

By default, switches ports are in dynamic desirable mode.

For some security reasons you might want to disable this protocol.

Viewing Port Mode

Switch#show interfaces switchport 

Changing Port Mode

Switch>en
Switch#conf t
Switch(config)#int e0/0
Switch(config-if)#switchport mode access|trunk|dynamic auto|dynamic desirable

Disabling DTP

Switch(config-if)#switchport mode trunk 
Switch(config-if)#switchport nonegotiate

Checking DTP Status

Switch#show dtp interface

Thank you for taking the time to read this article.

Keep up the good work!