Establishing a Trunk Link Between Cisco Switches

C

To establish a trunk link between two switches, both switches must have their corresponding interfaces configured with the trunk mode. The trunk mode is used to carry VLAN traffic between switches.

The neighboring switch is set to trunk or desirable mode, which means that the neighboring switch interface is already configured for trunking or is willing to negotiate to form a trunk link. In this scenario, the best action to take is to configure the interface on the local switch with the trunk mode.

Therefore, the correct answer is option D: configure switchport trunk dynamic desirable. This command configures the interface to actively attempt to form a trunk link and negotiate the parameters with the neighboring switch. The keyword "dynamic" allows the switchport to operate as a trunk if the neighboring switch is configured for trunking, and the keyword "desirable" indicates that the switchport will actively attempt to negotiate trunking with the neighboring switch.

Option A (configure switchport nonegotiate) is used to disable the negotiation of trunking parameters between switches, and this is not required in this scenario.

Option B (configure switchport mode dynamic desirable) is not the best answer because it lacks the keyword "trunk" to indicate that the interface is configured for trunking.

Option C (configure switchport mode dynamic auto) is used to configure the interface to negotiate the parameters of the link with the neighboring switch, but it will not force the interface to become a trunk link, which is required in this scenario.