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CCNA Data Center DCICN 640-911 Official Cert Guide by Chad Hintz, Wendell Odom

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Controlling Which VLANs Can Be Supported on a Trunk

Now that you know how to configure an interface to trunk VLANs from one switch to another, it is important to understand how to control which VLANs are allowed between them. The allowed VLAN list feature provides a mechanism for engineers to administratively disable a VLAN from a trunk. By default, switches include all possible VLANs (1–4094) in each trunk’s allowed VLAN list. However, the engineer can then limit the VLANs allowed on the trunk by using the following interface subcommand:

switchport trunk allowed vlan {add | all | except | remove|none} vlan-list

This command provides a way to easily add and remove VLANs from the list. For example, the add option ...

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