What configuration is required if you want to prevent trunk negotiation on a switch port?

To prevent trunk negotiation on a switch port, the configuration needed is to set the switch port to nonegotiate mode. This setting effectively disables Dynamic Trunking Protocol (DTP), which is responsible for automatically negotiating trunking between switches. By using the nonegotiate option, you are specifying that the port should not participate in any trunk negotiation process, thus ensuring that the port does not dynamically form a trunk with other switches.

Using nonegotiate is particularly useful in scenarios where you want to enforce specific configurations and prevent any unexpected trunking behavior. For example, if a port is meant to connect to a single device, such as an end host or a router, enabling nonegotiate ensures that no trunk links will be established automatically, which could lead to unintended access to multiple VLANs.

Setting the switch port to access mode does disable trunking for that port, but it does not prevent DTP from running on the interface. In access mode, the port will only accept untagged frames and cannot form a trunk, but DTP is still operational and may negotiate trunking if the switch port's mode is changed.

Dynamic auto allows the port to respond to DTP requests for trunking, which means it could end up forming a trunk