User's Manual

Table Of Contents
313
Users Manual of CS-6306R
29.1.1.5 Echo Detection
The echo mechanism is the basis of the detection algorithm. Once a UDLD device learns a new neighbor or
another synchronization request from an asynchronous neighbor, it will start or restart the detection window of
the local terminal and transmit an echo message for full agreement. Because all neighbors are demanded a
corresponding action, the echo sender expects an echos message. If the checkup window is over before a
legal echo is received, this link is thought to be a unidirectional one. In this case, link reconnection will be
triggered or the link down process on the port is enabled.
29.1.2 UDLD Configuration Task List
Globally Enabling or Disabling UDLD
Enabling or Disabling the UDLD Interface
Setting the Message Interval of the Aggressive Mode
Restarting the Interface Shut Down by UDLD
Displaying the UDLD State
29.1.3 UDLD Configuration Tasks
29.1.3.1 Globally Enabling or Disabling UDLD
In global configuration mode, run the following command to enable the UDLD function of all interfaces.
Command Purpose
udld [enable |
aggressive]
Enables the UDLD modules of all interfaces in some
mode.
In global configuration mode, run the following command to disable the UDLD function of all interfaces.
Command Purpose
no udld [enable |
aggressive]
Shuts down the UDLD modules of all interfaces.
If you enable or disable the UDLD function in global configuration mode, the UDLD
function will be performed on all interfaces.
UDLD of the Aggressive mode is a variation of UDLD, which can provide extra benefits. When UDLD is in
aggressive mode and the port stops transmitting the UDLD packets, UDLD will try to establish a link with its
neighbor again. If the times of tries exceed a certain number, the state of the port is changed into the
Error-Disable state and the link of the port is down. When UDLD is running, the ports at both terminals should
run in the same mode, or the expecting result cannot be obtained.