CLI Reference Guide-R04

Chapter 16 | UniDirectional Link Detection Commands
– 494 –
Command Usage
When a neighbor device is discovered by UDLD, the switch enters “detection state”
and remains in this state for specified detection-interval. After the detection-
interval expires, the switch tries to decide whether or the link is unidirectional
based on the information collected during “detection state.”
Example
Console(config)#udld detection-interval 10
Console(config)#
udld message-interval This command configures the message interval between UDLD probe messages for
ports in the advertisement phase and determined to be bidirectional. Use the no
form to restore the default setting.
Syntax
udld message-interval message-interval
no message-interval
message-interval – The interval at which a port sends UDLD probe
messages after linkup or detection phases. (Range: 7-90 seconds)
Default Setting
15 seconds
Command Mode
Global Configuration
Command Usage
During the detection phase, messages are exchanged at the maximum rate of one
per second. After that, if the protocol reaches a stable state and determines that the
link is bidirectional, the message interval is increased to a configurable value based
on a curve known as M1(t), a time-based function described in RFC 5171.
If the link is deemed anything other than bidirectional at the end of the detection
phase, this curve becomes a flat line with a fixed value of Mfast (7 seconds).
If the link is instead deemed bidirectional, the curve will use Mfast for the first four
subsequent message transmissions and then transition to an Mslow value for all
other steady-state transmissions. Mslow is the value configured by this command.
Example
This example sets the message interval to 10 seconds.
Console(config)#udld message-interval 10
Console(config)#