Modify Trunk Configuration Window

This window appears when you select a port and click Modify on the Configure Trunks tab of the VLAN window. Use it to:

When you finish with these tasks, click OK.

Selecting a Trunking Encapsulation Mode

To select a trunking encapsulation mode, select Negotiate, ISL, or 802.1Q from the Mode list.

If you select Negotiate, the trunk port will negotiate with linked ports on the better choice, ISL or 802.1Q.

If you configure an 802.1Q trunk, see Special 802.1Q Trunk Considerations. If this switch is in a VTP domain, see Disabling Pruning for changes you might need to make on the new trunk.

Restricting VLAN Membership

You can restrict the VLAN membership for a trunk interface by specifying which VLANs are allowed to use it. Enter the numbers of the allowed VLANs in the Allowed VLAN List section, and the interface forwards traffic for these alone.

Disabling Pruning

VLANs that are eligible for VTP pruning are identified in the VLAN Pruning Eligibility section. To disable VTP pruning on a VLAN, remove its number from the VLAN ID field.

Changing the Native VLAN

By default, the native VLAN is VLAN 1. To assign another VLAN to be the native VLAN, select a different VLAN ID from the Native VLAN list.