F Commands

This chapter describes the Cisco NX-OS interface commands that begin with F.

feature lacp

To enable the Link Aggregation Control Protocol (LACP), which bundles a number of physical ports together to form a single logical channel, use the feature lacp command. To disable LACP on the switch, use the no form of this command.

feature lacp

no feature lacp

 
Syntax Description

This command has no arguments or keywords.

 
Command Default

LACP is disabled.

 
Command Modes

Global configuration mode

 
Command History

Release
Modification

4.0(0)N1(1a)

This command was introduced.

 
Usage Guidelines

You must remove all the LACP configuration parameters from all EtherChannels on the switch before you can disable LACP.

Even after you enable LACP globally, you do not have to run LACP on all EtherChannels on the switch. You enable LACP on each channel mode using the channel-group mode command.

Examples

This example shows how to enable LACP EtherChannels on the switch:

switch(config)# feature lacp
 

 
Related Commands

Command
Description

show lacp

Displays information on LACP.

show feature

Displays whether or not LACP is enabled on the switch.

feature lldp

To enable the Link Layer Discovery Protocol (LLDP) on a device, use the feature lldp command in

global configuration mode. To disable the LLDP feature, use the no form of the command.

 

feature lldp

no feature lldp

 
Syntax Description

This command has no arguments or keywords.

 
Command Defaultis

Enabled

 
Command History

Release
Modification

4.0(0)N1(1a)

This feature was introduced.

5.2(1)N1(4)

The no form of the command was introduced.

 
Usage Guidelines

The Cisco Discovery Protocol (CDP) is a device discovery protocol that runs over Layer 2 (the data link

layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches). CDP allows

network management applications to automatically discover and learn about other Cisco devices

connected to the network.

To support non-Cisco devices and to allow for interoperability between other devices, the switch

supports the Link Layer Discovery Protocol (LLDP). LLDP is a neighbor discovery protocol that is used

for network devices to advertise information about themselves to other devices on the network. This

protocol runs over the data-link layer, which allows two systems running different network layer

protocols to learn about each other.

The following is an example on how to configure the feature lldp command and how to verify the

feature lldp command on the switch:
 
switch# feature lldp
 
switch# show running-config
 
!Command: show running-config
!Time: Tue Feb 10 12:36:03 2009
 
version 5.0(3)N1(1)
feature telnet
feature lldp
 
username admin password 5 $1$d8lkfqC8$4VfRuOoZTKvCtTq8VAKbq/ role network-admin
no password strength-check
ip domain-lookup
hostname switch
class-map type qos class-fcoe
class-map type qos match-all c1
match cos 1
<--Output truncated-->
switch#

 
Related Commands

Command
Description

lldp

Configures the global LLDP options on the switch.

lldp (Interface)

Configures the LLDP feature on an interface.

show feature

Displays that LLDP is enabled on the switch.

feature port-security

To enable port security on Layer 2 interfaces, use the feature port-security command. To disable port security, use the no form of this command.

feature port-security

no feature port-security

 
Syntax Description

This command has no arguments or keywords.

 
Command Default

Disabled

 
Command Modes

Global configuration mode

 
Command History

Release
Modification

5.1(3)N1(1)

This command was introduced.

 
Usage Guidelines

Use the port security feature to secure a port by limiting and identifying the MAC addresses of the switches that are allowed to access the port.

You can enable port security on a virtual port channel (vPC) port only if the following occurs:

  • Port security is enabled on both the vPC peers
  • Port security is enabled on the vPC port on both the vPC peers.

This command does not require a license.

Examples

This example shows how to enable port security on the switch:

switch# configure terminal
switch(config)# feature port-security
switch(config)#
 

This example shows how to disable port security on the switch:

switch# configure terminal
switch(config)# no feature port-security
switch(config)#
 

 
Related Commands

Command
Description

show feature

Displays the features that are enabled or disabled on the switch.

show port-security

Displays the port security configuration information.

switchport port-security

Configures the switchport parameters to establish port security.

 

feature udld

To enable the Cisco-proprietary Unidirectional Link Detection (UDLD) protocol, which allows ports that are connected through fiber optics or copper Ethernet cables to monitor the physical configuration of the cables and detect when a unidirectional link exists, use the feature udld command. To disable UDLD on the switch, use the no form of this command.

feature udld

no feature udld

 
Syntax Description

This command has no arguments or keywords.

 
Command Default

UDLD is disabled.

 
Command Modes

Global configuration mode

 
Command History

Release
Modification

4.0(1a)N1(1)

This command was introduced.

Examples

This example shows how to enable UDLD on the switch:

switch(config)# feature udld
 

 
Related Commands

Command
Description

show udld

Displays the administrative and operational UDLD status.

show feature

Displays whether or not UDLD is enabled on the switch.