KB.15.15

Example

To change the maximum number of attempts to four, enter the following command at the global

configuration level:

(HP_Switch_name#) link-keepalive retries 4

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-HP 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.

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

a command such as the following at the interface configuration level:

( HP_Switch_name#) interface llink-keepalive vlan 22

NOTE:

• 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 Table 3 (page 101) for potential

problems.

Viewing UDLD information

Syntax

show link-keepalive

Displays all the ports that are enabled for link-keepalive.

Syntax

show link-keepalive statistics

Displays detailed statistics for the UDLD-enabled ports on the switch.

Syntax

clear link-keepalive statistics

Clears UDLD statistics. This command clears the packets sent, packets received, and transitions

counters in the show link-keepalive statistics display.

Viewing summary information on all UDLD-enabled ports

Enter the show link-keepalive command.

Configuring uni-directional link detection 99