Udld (Configuration Mode) - Cisco AP775A - Nexus Converged Network Switch 5010 Command Reference Manual

udld (configuration mode)

S e n d c o m m e n t s t o n x 5 0 0 0 - d o c f e e d b a c k @ c i s c o . c o m
udld (configuration mode)
To configure the Unidirectional Link Detection (UDLD) protocol on the switch, use the udld command.
To disable UDLD, use the no form of this command.
Syntax Description
aggressive
message-time
timer-time
reset
Command Modes
Configuration mode
Command History Release
4.0(1a)N1(1)
Usage Guidelines
UDLD aggressive mode is disabled by default. You can configure UDLD aggressive mode only on
point-to-point links between network devices that support UDLD aggressive mode. If UDLD aggressive
mode is enabled, when a port on a bidirectional link that has a UDLD neighbor relationship established
stops receiving UDLD frames, UDLD tries to reestablish the connection with the neighbor. After eight
failed retries, the port is disabled.
To prevent spanning tree loops, normal UDLD with the default interval of 15 seconds is fast enough to
shut down a unidirectional link before a blocking port transitions to the forwarding state (with default
spanning tree parameters).
When you enable the UDLD aggressive mode, the following occurs:
•
•
In these cases, the UDLD aggressive mode disables one of the ports on the link, which prevents traffic
from being discarded.
Examples
The following example shows how to enable the aggressive UDLD mode for the switch:
switch# configure terminal
switch(config)# udld aggressive
Cisco Nexus 5000 Series Command Reference
2-100
udld {aggressive | message-time timer-time | reset}
no udld {aggressive | message-time | reset}
Enables UDLD in aggressive mode on the switch.
Sets the period of time between UDLD probe messages on ports that are in
advertisement mode and are currently determined to be bidirectional; valid
value is from 7 to 90 seconds. Default value is 15 seconds.
Resets all the ports that are shut down by UDLD and permit traffic to begin
passing through them again. Other features, such as spanning tree, will
behave normally if enabled.
Modification
This command was introduced.
One side of a link has a port stuck (both transmission and receive)
One side of a link remains up while the other side of the link is down
Chapter 2 Ethernet Commands
OL-16599-01