HP ProCurve J8766A Release Note page 31

traffic on the connected ports. UDLD-enabled ports, however, will prevent traffic from being sent
across a bad link by blocking the ports in the event that either the individual transmitter or receiver
for that connection fails.
Ports enabled for UDLD exchange health-check packets once every five seconds (the link-keepalive
interval). If a port does not receive a health-check packet from the port at the other end of the link
within the keepalive interval, the port waits for four more intervals. If the port still does not receive
a health-check packet after waiting for five intervals, the port concludes that the link has failed and
blocks the UDLD-enabled port.
When a port is blocked by UDLD, the event is recorded in the switch log or via an SNMP trap (if
configured); and other port blocking protocols, like spanning tree or meshing, will not use the bad
link to load balance packets. The port will remain blocked until the link is unplugged, disabled, or
fixed. The port can also be unblocked by disabling UDLD on the port.
Configuration Considerations
UDLD is configured on a per-port basis and must be enabled at both ends of the link. See the
■
note below for a list of ProCurve switches that support UDLD.
■ To configure UDLD on a trunk group, you must configure the feature on each port of the
group individually. Configuring UDLD on a trunk group's primary port enables the feature
on that port only.
■ Dynamic trunking is not supported. If you want to configure a trunk group that contains
ports on which UDLD is enabled, you must remove the UDLD configuration from the ports.
After you create the trunk group, you can re-add the UDLD configuration.
Note
UDLD interoperates with the following ProCurve switch series: 3400, 3500, 5300, 5400, 6200, 6400,
and 9300. Consult the release notes and current manuals for required software versions.
Configuring UDLD
The following commands allow you to configure UDLD via the CLI.
Syntax: [no] interface <port-list> link-keepalive
Enables UDLD on a port or range of ports.
To disable the feature, enter the no form of the command.
Default: UDLD disabled
Syntax: link-keepalive interval <interval>
Enhancements
Release L.10.07 Enhancements
25