F Commands

This chapter describes the Cisco NX-OS unicast routing commands that begin with the letter F.

feature bgp

To enable the Border Gateway Protocol (BGP), use the feature bgp command. To disable BGP, use the no form of this command.

feature bgp

no feature bgp

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration.

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the BGP feature before you can configure BGP.

This command requires the Enterprise Services license.

Examples

This example shows how to enable a BGP configuration:

switch(config)# feature bgp

 
Related Commands

Command
Description

show bgp

Displays BGP configuration information.

router bgp

Creates a BGP instance.
 

feature eigrp

To enable the Enhanced Interior Gateway Protocol (EIGRP), use the feature eigrp command. To disable EIGRP, use the no form of this command.

feature eigrp

no feature eigrp

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the EIGRP feature before you can configure EIGRP.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the EIGRP feature:

switch(config)# feature eigrp

 
Related Commands

Command
Description

show { ip | ipv6 } eigrp

Displays EIGRP configuration information.

router eigrp

Creates a EIGRP instance.
 

feature glbp

To enable the Gateway Load Balancing Protocol (GLBP), use the feature glbp command. To disable GLBP, use the no form of this command.

feature glbp

no feature glbp

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

You must globally enable GLBP before you can configure any GLBP options or create a GLBP group.

This command does not require a license.

Examples

This example shows how to enable GLBP:

switch(config)# feature glbp

 
Related Commands

Command
Description

authentication

Configures an authentication string for the GLBP group.

forwarder preempt

Configures a gateway to take over as AVF for a GLBP group if it has a higher priority than the current AVF.

ip (GLBP)

Activates the GLBP group.

load-balancing

Specifies the load-balancing method used by the AVG of GLBP.

preempt

Configures the gateway to take over as AVG for a GLBP group if it has a higher priority than the current AVG.

priority

Sets the priority level of the gateway within a GLBP group.

show glbp

Displays GLBP information.

timers

Configures the time between hello packets sent by the GLBP gateway and the time for which the virtual gateway and virtual forwarder information is considered valid.

timers redirect

Configures the time during which the AVG for a GLBP group continues to redirect clients to a secondary AVF.

track

Configures an interface to be tracked where the GLBP weighting changes are based on the state of the interface.

weighting

Specifies the initial weighting value of the GLBP gateway.

weighting track

Specifies a tracking object where the GLBP weighting changes are based on the availability of the object being tracked.

feature hsrp

To enter Hot Standby Router Protocol (HSRP) configuration mode and enable HSRP, use the feature hsrp command. To disable HSRP, use the no form of this command.

feature hsrp

no feature hsrp

 
Syntax Description

The command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

Use the feature hsrp command to enter HSRP configuration mode and enable HSRP.

This command does not require a license.

Examples

This example shows how to enable HSRP on Ethernet interface 1/1:

switch# config t
switch(config)# feature hsrp
switch(config-hsrp)#

 
Related Commands

Command
Description

hsrp group

Creates and activates an HSRP group.

show hsrp

Displays HSRP information.

feature imp

To enable the authentication package for Open Short Path First version 3 (OSPFv3) packets, use the feature imp command. To disable the authentication package, use the no form of this command.

feature imp

no feature imp

 
Syntax Description

The command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

7.3(1)D1(1)

This command was introduced.

 
Usage Guidelines

This command does not require a license.

Examples

This example shows how to enable authentication package:

switch# config terminal
switch(config)# feature imp
switch(config)#

feature isis

To enable the Intermediate System to Intermediate System Protocol (IS-IS), use the feature isis command. To disable ISIS, use the no form of this command.

feature isis

no feature isis

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the IS-IS feature before you can configure IS-IS.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the IS-IS feature:

switch(config)# feature isis

 
Related Commands

Command
Description

show isis

Displays IS-IS configuration information.

router isis

Creates an IS-IS instance.

feature ospf

To enable the Open Shortest Path First Protocol (OSPF), use the feature ospf command. To disable OSPF, use the no form of this command.

feature ospf

no feature ospf

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the OSPF feature before you can configure OSPF.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the OSPF feature:

switch(config)# feature ospf

 
Related Commands

Command
Description

show ospf

Displays OSPF configuration information.

router ospf

Creates an OSPF instance.

feature ospfv3

To enable the Open Shortest Path First version 3 Protocol (OSPFv3), use the feature ospfv3 command. To disable OSPFv3, use the no form of this command.

feature ospfv3

no feature ospfv3

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the OSPFv3 feature before you can configure OSPFv3.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the OSPv3 feature:

switch(config)# feature ospfv3

 
Related Commands

Command
Description

show ospfv3

Displays OSPFv3 configuration information.

router ospfv3

Creates an OSPFv3 instance.

feature pbr

To enable the policy-based routing (PBR) feature, use the feature pbr command. To disable PBR, use the no form of this command.

feature pbr

no feature pbr

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the PBR feature before you can configure policy-based routing.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the PBR feature:

switch(config)# feature pbr

 
Related Commands

Command
Description

ip policy route-map

Assigns a policy-based route map to an interface.

show ip policy

Displays information about policy-based routing.

feature rip

To enable the Routing Information Protocol (RIP), use the feature rip command. To disable RIP, use the no form of this command.

feature rip

no feature rip

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the RIP feature before you can configure RIP.

This command does not require a license.

Examples

This example shows how to enable the RIP feature:

switch(config)# feature rip

 
Related Commands

Command
Description

show rip

Displays RIP configuration information.

router rip

Creates a RIP instance.

feature vrrp

To enable the Virtual Router Redundancy Protocol (VRRP), use the feature vrrp command. To disable VRRP, use the no form of this command.

feature vrrp

no feature vrrp

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.0(1)

This command was introduced.

 
Usage Guidelines

You must enable the VRRP feature before you can configure VRRP.

This command does not require a license.

Examples

This example shows how to enable the VRRP feature:

switch(config)# feature vrrp

 
Related Commands

Command
Description

show vrrp

Displays VRRP configuration information.

clear vrrp

Clears all the software counters for the specified virtual router.
 

feature vrrpv3

To enable Virtual Router Redundancy Protocol (VRRP) version 3 and Virtual Router Redundancy Service (VRRS), use the feature vrrpv3 command. To disable VRRPv3 and VRRS in a VDC, use the no form of this command.

feature vrrpv3

no feature vrrpv3

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration mode

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

6.2(2)

This command was introduced.

 
Usage Guidelines

If VRRPv2 is configured, use the no feature vrrp command in global configuration mode to remove the VRRPv2 configuration and then use the feature vrrpv3 command to enable VRRPv3.

This command requires the Enterprise Services license.

Examples

This example shows how to enable VRRPv3 and VRRS:

switch# configure terminal
switch(config)# feature vrrpv3
switch(config)#
 
This example shows how to disable VRRPv3 and VRRS:
 
switch(config)# no feature vrrpv3

 
Related Commands

Command
Description

vrrpv3 address-family

Creates a VRRPv3 group and enters VRRPv3 group configuration mode.

feature wccp

To enable the Web Cache Communication Protocol (WCCP), use the feature wccp command. To disable WCCP, use the no form of this command.

feature wccp

no feature wccp

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modified

4.2(1)

This command was introduced.

 
Usage Guidelines

You must enable the WCCP feature before you can configure WCCPv2.

This command does not require a license.

Examples

This example shows how to enable the WCCP feature:

switch(config)# feature wccp
switch(config)# show ip wccp
Global WCCP information:
Router information:
Router Identifier: 20.20.20.2
Protocol Version: 2.0
 

 
Related Commands

Command
Description

clear ip wccp

Clears all the software counters for WCCPv2.

show running-config wccp

Displays the WCCPv2 configuration.

show ip wccp

Displays the status of the WCCP service group.

 
 

flush-routes (OSPF)

To flush routes on a nongraceful controlled restart for the Open Shortest Path First (OSPF) protocol, use the flush-routes command. To disable this feature, use the no form of this command.

flush-routes

no flush-routes

 
Syntax Description

None

 
Defaults

Disabled

 
Command Modes

Router configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

Use the flush-routes command when the OSPF Graceful Restart feature is not enabled.

This commands causes OSPF to unregister from the unicast RIB when OSPF shuts down. The unicast RIB removes all the routes associated with this OSPF instance. If you do not configure the flush-routes command, OSPF will not unregister and the OSPF routes will be stale. The OSPF routs are eventually removed from the unicast RIB after a timeout period. If OSPF comes back up in p in graceful restart mode, the routes will be refreshed in the unicast RIB.

This command requires the Enterprise Services license.

Examples

This example shows how to flush routes for a nongraceful restart:

switch(config)# router ospf 202
switch(config-router)# flush-routes
 

 
Related Commands

Command
Description

graceful-restart

Enables OSPF Graceful Restart.

flush-routes (OSPFv3)

To flush routes on a nongraceful controlled restart for the Open Shortest Path First version 3 (OSPFv3) protocol, use the flush-routes command. To disable this feature, use the no form of this command.

flush-routes

no flush-routes

 
Syntax Description

None

 
Defaults

Disabled

 
Command Modes

Router configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

Use the flush-routes command when the OSPFv3 Graceful Restart feature is not enabled.

This commands causes OSPF to unregister from the unicast RIB when OSPFv3 shuts down. The unicast RIB removes all the routes associated with this OSPF instance. If you do not configure the flush-routes command, OSPFv3 will not unregister and the OSPFv3 routes will be stale. The OSPFv3 routs are eventually removed from the unicast RIB after a timeout period. If OSPFv3 comes back up in p in graceful restart mode, the routes will be refreshed in the unicast RIB.

This command requires the Enterprise Services license.

Examples

This example shows how to flush routes for a nongraceful restart:

switch(config)# router ospfv3 202
switch(config-router)# flush-routes
 

 
Related Commands

Command
Description

graceful-restart

Enables OSPFv3 graceful restart.

follow

To configure a regular Hot Standby Redundancy Protocol (HSRP) group as a slave group, use the follow command. To return the slave group to a regular HSRP group, use the no form of this command.

follow master-group

no follow master-group

 
Syntax Description

master-group

Master group.

 
Defaults

None

 
Command Modes

config-if-hsrp mode

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

6.2(2)

This command was introduced.

 
Usage Guidelines

Configuring an HSRP group as a slave group clears the group’s other configurations, such as its virtual IP address without notification, so you must enter the follow command before you enter the ip command.

Slave groups may forward reference master group names that are undefined.

This command requires the Enterprise Services license.

Examples

This example shows how to configure a regular HSRP group as a slave group:

switch# configure terminal
switch(config)# interface ethernet 3/5
switch(config-if)# ip address 11.0.0.1/24
switch(config-if)# hsrp version 2
switch(config-if)# hsrp mac-refresh 90
switch(config-if)# hsrp 10
switch(config-if-hsrp)# name Master-Group-1
switch(config-if-hsrp)# follow Master-Group-1
switch(config-if-hsrp)#

 

This example shows how to remove a regular HSRP group from a slave group:

switch(config-if-hsrp)# no follow Master-Group-1

 
Related Commands

Command
Description

hsrp

Creates an HSRP group and enters HSRP configuration mode.

forwarder preempt

To configure a gateway to take over as the active virtual forwarder (AVF) for a Gateway Load Balancing Protocol (GLBP) group if the current AVF falls below its low weighting threshold, use the forwarder preempt command. To disable this function, use the no form of this command.

forwarder preempt [ delay minimum seconds ]

no forwarder preempt [ delay minimum seconds ]

 
Syntax Description

delay minimum seconds

(Optional) Specifies a minimum number of seconds that the gateway delays before taking over the role of AVF. The range is from 0 to 3600 seconds with a default delay of 30 seconds.

 
Defaults

Forwarder preemption is enabled with a default delay of 30 seconds.

 
Command Modes

GLBP configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

This command does not require a license.

Examples

This example shows how to configure a gateway to preempt the current AVF when the current AVF falls below its low weighting threshold. If the gateway preempts the current AVF, it waits 60 seconds before taking over the role of the AVF.

switch(config)# interface ethernet 1/1
switch(config-if)# glbp 2
switch(config-glbp)# forwarder preempt delay minimum 60

 
Related Commands

Command
Description

glbp

Enters GLBP configuration mode and creates a GLBP group.