Dynamic Trunking Protocol (DTP). If a port can become a trunk, it may also have the ability to trunk automatically, and in some cases even negotiate what type of trunking to use on the port. DTP provides this ability to negotiate the trunking method with the other device.
(All Virtual LANs VLAN Trunking Protocol (VLANs VTP) Configuration Examples and TechNotes)
(All Virtual LANs VLAN Trunking Protocol (VLANs VTP) Configuration Example and TechNotes)