Cisco AJ732A - MDS 9134 Fabric Switch Configuration Manual page 103

Chapter 5 Configuring Ethernet Interfaces
S e n d f e e d b a c k 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
Figure 5-1
TX
TX
Default UDLD Configuration
Table 5-1
Table 5-1
Feature
UDLD global enable state
UDLD aggressive mode
UDLD per-port enable state for fiber-optic media
UDLD per-port enable state for twisted-pair (copper)
media
For information on configuring the UDLD for the device and its port, see the
Mode" section on page
UDLD Aggressive and Nonaggressive Modes
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, nonaggressive 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.
OL-16597-01
Unidirectional Link
Device A
RX
RX
Device B
shows the default UDLD configuration.
UDLD Default Configuration
5-5.
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
Default Value
Globally disabled
Disabled
Enabled on all Ethernet fiber-optic LAN ports
Disabled on all Ethernet 10/100 and
1000BASE-TX LAN ports
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
Information About Ethernet Interfaces
"Configuring the UDLD
5-3