Ethernet interfaces on Catalyst 2960 and Catalyst 3560 Series switches support different trunking modes with the help of DTP:

Figure 1 illustrates the results of the DTP configuration options on opposite ends of a trunk link connected to Catalyst 2960 switch ports.

Configure trunk links statically whenever possible. The default DTP mode is dependent on the Cisco IOS Software version and on the platform. To determine the current DTP mode, issue the show dtp interface command as shown in Figure 2.

Use the Syntax Checker in Figure 3 to determine the DTP mode on interface F0/1.

Note: A general best practice is to set the interface to trunk and nonegotiate when a trunk link is required. On links where trunking is not intended, DTP should be turned off.