Configuring UDLD for tagged ports

The default implementation of UDLD sends the UDLD control packets untagged, even across tagged ports. If an untagged UDLD packet is received by a non-Hewlett Packard Enterprise switch, that switch may reject the packet. To avoid such an occurrence, you can configure ports to send out UDLD control packets that are tagged with a specified VLAN.

enable ports to receive and send UDLD control packets tagged with a specific VLAN ID

switch# interface llink-keepalive vlan 22

  • You must configure the same VLANs that will be used for UDLD on all devices across the network; otherwise, the UDLD link cannot be maintained.

  • If a VLAN ID is not specified, UDLD control packets are sent out of the port as untagged packets.

  • To re-assign a VLAN ID, re-enter the command with the new VLAN ID number. The new command overwrites the previous command setting.

  • When configuring UDLD for tagged ports, you may receive a warning message if there are any inconsistencies with the VLAN configuration of the port. See Viewing port status and configuration for potential problems.