Default Udld Configuration; Udld Aggressive And Nonaggressive Modes; Svi Autostate - Cisco Nexus 3548 Configuration Manual
Nx-os interfaces release 9x
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Also See for Nexus 3548:
- Command reference manual (556 pages) ,
- Configuration manual (230 pages) ,
- Installation manual (112 pages)
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Configuring Layer 2 Interfaces
Figure 1: Unidirectional Link
Default UDLD Configuration
The following table shows the default UDLD configuration.
Table 1: UDLD Default Configuration
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
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:
• 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
In these cases, the UDLD aggressive mode disables one of the ports on the link, which prevents traffic from
being discarded.
SVI Autostate
The Switch Virtual Interface (SVI) represents a logical interface between the bridging function and the routing
function of a VLAN in the device. By default, when a VLAN interface has multiple ports in the VLAN, the
SVI goes to the down state when all the ports in the VLAN go down.
Cisco Nexus 3548 Switch NX-OS Interfaces Configuration Guide, Release 9x
Default UDLD Configuration
Default Value
Globally disabled
Disabled
Enabled on all Ethernet fiber-optic LAN ports
Enabled
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