DTP (Dynamic Trunking Protocol)

Protocol that helps to determine which trunking protocol are supported to establish a trunk.

This is also called Trunk Negotiation process.

The process allow you to setup a port to be a particular mode

In which:

1. access: never turns to be a trunk
2. dynamic desirable: actively try to be a trunk
3. dynamic auto: can be a trunk if the condition allows
4. trunk: port is always a trunk, doesn't matter

By default it's dynamic auto for Cisco switches

[!important]
Trunk negotiation includes the VTP (VLAN Trunking Protocol) in process. For DTP (Dynamic Trunking Protocol) successfully negotiate, both switch must have the same VTP.