13.12. VRRP Commands

Command Purpose

To configure the interval between successive advertisements sent by the master virtual router in a Virtual Router Redundancy Protocol (VRRP) group, use the advertisement-interval command in router configuration mode. To restore the default value, use the no form of this command.

Prerequisites

Command Syntax

advertisement-interval interval

no advertisement-interval

Command Mode

Router Configuration

Default

Default is 1 second.

Usage

The advertisements sent by the master virtual router communicate the state and priority of the current master virtual router.

The advertisement-interval command configures the time between successive advertisement packets and the time before other routers declare the master router to be down. Routers or access servers on which timer value are not configured can learn timer values from the master router. The timers configured on the master router always override any other timer settings. All routers in a VRRP group must use the same timer value. If the same timer value is not set, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Examples

The following example shows how to configure the master virtual router to send advertisements every 4 seconds:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# advertisement-interval 4

Related Commands

advertisement-interval msec

Command Purpose

To configure the advertisement interval with milli-second mode between successive advertisements sent by the master virtual router in a VRRP group, use the advertisement-interval msec command in router configuration mode.

Prerequisites

Command Syntax

advertisement-interval msec interval

Command Mode

Router Configuration

Default

None

Usage

The advertisements be sent by the master virtual router communicate thestate and priority of the current master virtual router.

The advertisement-interval msec command configures the time between successive advertisement packets and the time before other routers declare the master router to be down. Routers or access servers on which timer values are not configured can learn timer values from the master router. The timers configured on the master router always override any other timer settings. All routers in a VRRP group must use the same timer value. If the same timer value is not set, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master.

Examples

The following example shows how to configure the master virtual router to send advertisements every 100 milli-seconds:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# advertisement-interval msec 100

Related Commands

advertisement-interval

Command Purpose

To enable the Virtual Router Redundancy Protocol (VRRP) protocol on a specified interface, use the interface command in router mode.

To disable VRRP protocol on this interface, use the no form of this command.

Prerequisites

Command Syntax

interface INTERFACE-ID

no interface

Command Mode

Router Configuration

Default

None

Usage

The max VRRP group number should be no more than 3 for one VRRP interface.

Examples

The following is a sample output from the interface command:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)#interface eth-0-1

Related Commands

router vrrp

Command Purpose

To enable the backup router to learn advertisement interval from master router, use the learnmaster-mode true command in router mode.

To disable learn advertisement interval from master router, use the learnmaster-mode false command.

Prerequisites

Command Syntax

learnmaster-mode (true|false)

Command Mode

Router Configuration

Default

Default is false.

Usage

By default, backup router does not learn advertisement interval from master router.

Examples

The following example shows how to configure a backup router learning advertisement interval from master router.:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# learnmaster-mode true

Related Commands

router vrrp

Command Purpose

To configure the router to take over as master virtual router for a Virtual Router Redundancy Protocol (VRRP) group if it has higher priority than the current master virtual router, use the preempt-mode enable command in router mode. To disable this function, use the preempt-mode disable command.

Prerequisites

Command Syntax

preempt-mode (true|false)

Command Mode

Router Configuration

Default

Default is true.

Usage

By default, the router configured preempt-mode true will take over as master virtual router for the group if it has a higher priority than the current master virtual router.

Examples

The following example shows how to configure the router to preempt the current master virtual router when its priority of 200 is higher than that of the current master virtual router:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# preempt-mode true
Switch(config-router)# priority 200

Related Commands

preempt delay

Command Purpose

To configure the master down interval when preempt takes effect.

Prerequisites

Command Syntax

preempt delay time

Command Mode

Router Configuration

Default

Default is 0 second.

Usage

The original master down interval =(3*advt_interval) + skew_time. when preempt delay time is configured, then master down interval =(3*advt_interval) + skew_time + preempt_delay. By default, preempt delay is 0 second.

Examples

The following example shows how to configure the router to preempt the current master virtual router when its priority of 200 is higher than that of the current master virtual router, but delay 30 seconds to preempt:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# preempt-mode true
Switch(config-router)# priority 200
Switch(config-router)# preempt delay 30

Related Commands

preempt-mode

Command Purpose

To set the priority level of the router within a Virtual Router Redundancy Protocol (VRRP) group, use the priority command in router configuration mode. To remove the priority level of the router, use the no form of this command.

Prerequisites

Command Syntax

priority level

no priority

Command Mode

Router Configuration

Default

Default is 100

Usage

Use this command to control which router becomes the master virtual router.

Examples

The following example shows how to configure the router with a priority of 254:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)#priority 254

Related Commands

router vrrp

Command Purpose

To create a Virtual Router Redundancy Protocol (VRRP) group, use the router VRRP command in Global Config mode. To remove this VRRP group, use the no form of this command.

Prerequisites

Command Syntax

router vrrp GROUP (vrf NAME| ) (uniform-mac| )

no router vrrp GROUP

Command Mode

Global Config

Default

None

Usage

None

Examples

The following is a sample shows how to create a VRRP group:

Switch# configure terminal
Switch(config)# router vrrp 1

Related Commands

None

Command Purpose

To configure the Virtual Router Redundancy Protocol (VRRP) to track an object, use the track command in router configuration mode.

To disable the tracking, use the no form of this command.

Prerequisites

Command Syntax

track OBJ_ID (decrement VALUE)

no track

Command Mode

Router Configuration

Default

None

Usage

Use track to monitor an up link interface, so that when the monitoring interface is down, backup can change to master router.

Only 1 track object is valid for one special VRRP group, and the later configured track object will always overwrite the previous one.

Examples

The following is a sample output from the track command:

Switch# configure terminal
Switch(config)# track 10 interface eth-0-1 linkstate
Switch(config)# router vrrp 1
Switch(config-router)# track 10

Related Commands

router vrrp

Command Purpose

To enable a VRRP session, use the enable command in router configuration mode.

To disable a VRRP session, use the disable command in router configuration mode.

Prerequisites

Command Syntax

enable

disable

Command Mode

Router Configuration

Default

None

Usage

None

Examples

The following is a sample shows how to enable a VRRP session:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# enable

The following is a sample shows how to disable a VRRP session:

Switch# configure terminal
Switch(config)# router vrrp 1
Switch(config-router)# disable

Related Commands

None

Command Purpose

To enable the Virtual Router Redundancy Protocol (VRRP) on an interface and identify the IP address of the virtual router, use the virtual-IP command in router configuration mode. To disable VRRP on the interface and remove the IP address of the virtual router, use the no form of this command.

Prerequisites

Command Syntax

virtual-ip IP-ADDRESS

no virtual-ip

Command Mode

Router Configuration

Default

None

Usage

For VRRP to elect a designated router, at least one router on the cable must have been configured with the primary address of the virtual router.

VRRP does not support address learning. All addresses must be configured.

All routers in the VRRP group must be configured with the same primary address for the virtual router. If different primary addresses are configured, the routers in the VRRP group will not communicate with each other and any mis-configured routers in the group will change their state to master.

The virtual IP address must be in the same subnet with VRRP interface, and if virtual IP is equal to the interface IP address, it is called IP address owner.

Examples

The following example shows how to enable VRRP on eth-0-1. The VRRP group is 1. IP address 10.0.1.20 is the address of the virtual router:

Switch# configure terminal
Switch(config)# interface eth-0-1
Switch(config-if)# no switchport
Switch(config-if)#ip address 10.0.1.1/24
Switch(config)# router vrrp 1
Switch(config-router)#interface eth-0-1
Switch(config-router)#virtual-ip 10.0.1.20
Switch(config-router)#enable

Related Commands

router vrrp

Command Purpose

To display a brief or detailed status of one or all configured Virtual Router Redundancy Protocol (VRRP) groups on the router, use the show VRRP command in Privileged EXEC mode.

Prerequisites

Command Syntax

show vrrp (GROUP| )

Command Mode

Privileged EXEC

Default

None

Usage

If no group is specified, all groups are displayed.

Examples

The following is a sample output from the show VRRP command:

Switch# show vrrp
VRID<1\>
State : Master
Virtual IP : 10.0.20.254(Not IP owner)
Interface : eth-0-10
VMAC : 0000.5e00.0101
Advt timer : 1
Preempt mode : TRUE
Conf pri : 200 Run pri : 200
Master router ip : 10.0.20.1
Master priority : 200
Master advt timer : 1
Master down timer : 3
Preempt delay : 100 second(s)
Learn master mode : FALSE

Related Commands

router vrrp