Supporting Multiple VLANs on a Single Trunk
Resolving trunk link problems

If a problem exists with a trunk link, or if a trunk link cannot be established, check the following:

  • Verify that the interface mode configured on both ends of the link is identical or valid for negotiated links. The interface mode should be trunk, dynamic, or nonegotiate.
  • Verify the trunk encapsulation type configured on both ends of the link is valid and compatible.
  • For 802.1Q links, verify that the native VLAN is the same on both ends of the trunk.
NOTE:

If the trunk appears configured correctly on both ends or if the configuration has changed and no trunk forms, shutdown the interfaces on both ends of the trunk, check for a match in the configuration, and then bring the interfaces up to see if the trunk forms correctly.