Cisco IOS Software Releases 12.3 T

Table Of Contents

VRRP Object Tracking

Contents

Restrictions for VRRP Object Tracking

Information About VRRP Object Tracking

Object Tracking

VRRP Object Tracking Feature Design

Benefits of VRRP Object Tracking

How to Configure VRRP Object Tracking

Configuring VRRP Object Tracking

Verifying VRRP Object Tracking

Configuration Examples for VRRP Object Tracking

VRRP Object Tracking: Example

VRRP Object Tracking Verification: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

show vrrp

vrrp track

Glossary

VRRP Object Tracking

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The VRRP Object Tracking feature extends the capabilities of the Virtual Router Redundancy Protocol (VRRP) to allow tracking of specific objects within the router that can alter the priority level of a virtual router for a VRRP group. For example, a WAN interface can be tracked and if it goes down, then the priority of the VRRP group can be lowered, which may allow another VRRP router to become the new group master virtual router.

Feature History for the VRRP Object Tracking Feature

Release	Modification
12.3(2)T	This feature was introduced.
12.2(25)S	This feature was integrated into Cisco IOS Release 12.2(25)S.

Finding Support Information for Platforms and Cisco IOS Software Images

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Contents

•Restrictions for VRRP Object Tracking

•Information About VRRP Object Tracking

•How to Configure VRRP Object Tracking

•Configuration Examples for VRRP Object Tracking

•Additional References

•Command Reference

•Glossary

Restrictions for VRRP Object Tracking

If a VRRP group is the IP address owner, its priority is fixed at 255 and can not be reduced through object tracking.

Information About VRRP Object Tracking

Before you configure the VRRP Object Tracking feature, you should understand the following concepts:

•Object Tracking

•VRRP Object Tracking Feature Design

•Benefits of VRRP Object Tracking

Object Tracking

Object tracking is an independent process that manages creating, monitoring, and removing tracked objects such as the state of the line-protocol of an interface. Clients such as HSRP, GLBP, and now VRRP register their interest with specific tracked objects and act when the state of an object changes.

Each tracked object is identified by a unique number that is specified on the tracking command-line interface (CLI). Client processes such as VRRP use this number to track a specific object.

The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to interested client processes, either immediately or after a specified delay. The object values are reported as either up or down.

VRRP Object Tracking Feature Design

The VRRP Object Tracking feature gives VRRP access to all the objects available through the tracking process. The tracking process provides the ability to track individual objects such as a the state of an interface line protocol, state of an IP route, or the reachability of a route.

VRRP provides an interface to the tracking process. Each VRRP group can track multiple objects that may affect the priority of the VRRP router. You specify the object number to be tracked and VRRP will be notified of any change to the object. VRRP increments (or decrements) the priority of the virtual router based on the state of the object being tracked.

Benefits of VRRP Object Tracking

VRRP object tracking provides a way to ensure the best VRRP router is Master for the group by altering VRRP priorities to the status of tracked objects such as interface or IP route states.

How to Configure VRRP Object Tracking

This section contains the following procedure:

•Configuring VRRP Object Tracking

Configuring VRRP Object Tracking

This task configures VRRP object tracking.

SUMMARY STEPS

1. enable

2. configure terminal

3. track object-number interface type number {line-protocol | ip routing}

4. interface type-number

5. vrrp [group-number] ip ip-address

6. vrrp [group-number] priority level

7. vrrp [group-number] track object-number [decrement priority]

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	track object-number interface type number {line-protocol | ip routing} Example: Router(config)# track 2 interface serial 6 line-protocol	Configures an interface to be tracked where changes in the state of the interface affect the priority of a VRRP group. •This command configures the interface and corresponding object number to be used with the vrrp track command. •The line-protocol keyword tracks whether the interface is up. The ip routing keyword also checks that IP routing is enabledand active on the interface. •You can also use the track ip route command to track the reachability of an IP route or a metric type object.
Step 4	interface type number Example: Router(config)# interface Ethernet 2	Enters interface configuration mode.
Step 5	vrrp [group-number] ip ip-address Example: Router(config-if)# vrrp 1 10.0.1.20	Enables VRRP on an interface and identifies the IP address of the virtual router.
Step 6	vrrp [group-number] priority level Example: Router(config-if)# vrrp 1 priority 120	Sets the priority level of the router within a VRRP group.
Step 7	vrrp [group-number] track object-number [decrement priority] Example: Router(config-if)# vrrp 1 track 2 decrement 15	Configures VRRP to track an object.

Verifying VRRP Object Tracking

To verify VRRP object tracking, use the following commands:

SUMMARY STEPS

1. enable

2. show track [object-number]

3. show vrrp [brief | group]

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show track [object-number] Example: Router# show track 1	Displays tracking information.
Step 3	show vrrp [brief | group] Example: Router# show vrrp	Displays a brief or detailed status of one or all VRRP groups on the router.

Configuration Examples for VRRP Object Tracking

This section provides the following configuration examples:

•VRRP Object Tracking: Example

•VRRP Object Tracking Verification: Example

VRRP Object Tracking: Example

In the following example, the tracking process is configured to track the state of the line protocol on serial interface 0/1. VRRP on ethernet interface 1/0 then registers with the tracking process to be informed of any changes to the line protocol state of serial interface 0/1. If the line protocol state on serial interface 0/1 goes down, then the priority of the VRRP group is reduced by 15.

track 1 interface Serial0/1 line-protocol

!

interface Ethernet1/0

 ip address 12.0.0.1 255.0.0.0

 vrrp 1 ip 12.0.0.2

 vrrp 1 priority 120

 vrrp 1 track 1 decrement 15

VRRP Object Tracking Verification: Example

The following examples verify the configuration shown in the "VRRP Object Tracking: Example" section:

Router# show vrrp

Ethernet1/0 - Group 1  

  State is Master  

  Virtual IP address is 12.0.0.2

  Virtual MAC address is 0000.5e00.0101

  Advertisement interval is 1.000 sec

  Preemption is enabled

   min delay is 0.000 sec

  Priority is 105 

   Track object 1 state Down decrement 15

  Master Router is 12.0.0.1 (local), priority is 105 

  Master Advertisement interval is 1.000 sec

  Master Down interval is 3.531 sec

Router# show track

Track 1 

  Interface Serial0/1 line-protocol

  Line protocol is Down (hw down)

   1 change, last change 00:06:53

  Tracked by:

   VRRP Ethernet1/0 1

Additional References

The following section provides additional information related to the VRRP Object Tracking feature:

Related Documents

Related Topic	Document Title
VRRP configuration tasks	Virtual Router Redundancy Protocol feature document, Release 12.2(13)T
VRRP commands: complete command syntax, command mode, defaults, usage guidelines, and examples	Cisco IOS IP Command Reference, Volume 1 of 4: Addressing and Services, Release 12.3
Object tracking within Cisco IOS software	Enhanced Object Tracking feature document, Release 12.2(15)T

Standards

Standards	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—

MIBs

MIBs	MIBs Link
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

RFCs

RFCs	Title
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.	—

Technical Assistance

Description	Link
Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/public/support/tac/home.shtml

Command Reference

This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.3T command reference publications.

New Command

•vrrp track

Modified Command

•show vrrp

show vrrp

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.

show vrrp [brief | group]

Syntax Description

brief	(Optional) Provides a summary view of the group information.
group	(Optional) Virtual router group number of the group for which information is to be displayed. The group number is configured with the vrrp ip command.

Command Modes

Privileged EXEC

Command History

Release	Modification
12.0(18)ST	This command was introduced.
12.0(22)S	This command was integrated into Cisco IOS Release 12.0(22)S.
12.2(13)T	This command was integrated into Cisco IOS Release 12.2(13)T.
12.2(14)S	This command was integrated into Cisco IOS Release 12.2(14)S.
12.3(2)T	This command was enhanced to display the state of a tracked object.
12.2(25)S	This command was integrated into Cisco IOS Release 12.2(25)S.

Usage Guidelines

If no group is specified, all groups are displayed.

Examples

The following is sample output for the show vrrp command:

Router# show vrrp

Ethernet1/0 - Group 1 

State is Master 

Virtual IP address is 10.2.0.10 

Virtual MAC address is 0000.5e00.0101 

Advertisement interval is 3.000 sec 

Preemption is enabled 

 min delay is 0.000 sec 

Priority 100 

 Track object 1 state down decrement 15

Master Router is 10.2.0.1 (local), priority is 100 

Master Advertisement interval is 3.000 sec 

Master Down interval is 9.609 sec

Ethernet1/0 - Group 2 

State is Master 

Virtual IP address is 10.0.0.20 

Virtual MAC address is 0000.5e00.0102 

Advertisement interval is 1.000 sec 

Preemption is enabled 

 min delay is 0.000 sec 

Priority 95 

Master Router is 10.0.0.1 (local), priority is 95 

Master Advertisement interval is 1.000 sec 

Master Down interval is 3.628 sec

Table 1 describes the significant fields shown in the display.

Table 1 show vrrp Field Descriptions

Field	Description
Ethernet1/0 - Group	Interface type and number, and VRRP group number.
State is	Role this interface plays within VRRP (master or backup).
Virtual IP address is	Virtual IP address for this group.
Virtual MAC address is	Virtual MAC address for this group.
Advertisement interval is	Interval at which the router will send VRRP advertisements when it is the master virtual router. This value is configured with the vrrp timers advertise command.
Preemption is	Indication of whether preemption is enabled or disabled.
Track object	Object number representing the object to be tracked.
state	State value (up or down) of the object being tracked.
decrement	Amount by which the priority of the router is decremented (or incremented) when the tracked object goes down (or comes back up).
Priority	Priority of the interface.
Master Router is	IP address of the current master virtual router.
priority is	Priority of the current master virtual router.
Master Advertisement interval is	Advertisement interval of the master virtual router.
Master Down interval is	Calculated time that the master virtual router can be down before the backup virtual router takes over.

The following is sample output from the show vrrp command with the brief keyword:

Router# show vrrp brief

Interface	     Grp  Prio   Time   Own  Pre  State    Master addr    Group addr

Ethernet1/0    1   100    3609          P  Master   1.0.0.4        1.0.0.10

Ethernet1/0    2   105    3589          P  Master   1.0.0.4        1.0.0.20

Table 2 describes the significant fields shown in the display.

Table 2 show vrrp brief Field Descriptions

Field	Description
Interface	Interface type and number.
Grp	VRRP group to which this interface belongs.
Prio	VRRP priority number for this group.
Time	Calculated time that the master virtual router can be down before the backup virtual router takes over.
Own	IP address owner.
Pre	Preemption. P indicates that preemption is enabled. If this field is empty, preemption is disabled.
State	Role this interface plays within VRRP (master or backup).
Master addr	IP address of the master virtual router.
Group addr	IP address of the virtual router.

Related Commands

Command	Description
vrrp ip	Enables VRRP on an interface and identifies the IP address of the virtual router.

vrrp track

To configure the Virtual Router Redundancy Protocol (VRRP) to track an object, use the vrrp track command in interface configuration mode. To disable the tracking, use the no form of this command.

vrrp [group-number] track object-number [decrement priority]

no vrrp [group-number] track object-number [decrement priority]

Syntax Description

group-number	(Optional) Group number to which the tracking applies.
object-number	Object number in the range from 1 to 500 representing the object to be tracked.
decrement priority	(Optional) Amount by which the priority for the router is decremented (or incremented) when the tracked object goes down (or comes back up). The default value is 10. Decrements can be set to any value between 1 and 255.

Defaults

The default decrement value is 10. The range is from 1 and 255.

Command Modes

Interface configuration

Command History

Release	Modification
12.3(2)T	This command was introduced.
12.2(25)S	This command was integrated into Cisco IOS Release 12.2(25)S.

Usage Guidelines

You can configure VRRP to track specific objects, such as an interface or IP route, that can alter the priority level of a virtual router for a VRRP group. The tracked objects are first defined using the track interface or track ip route global configuration command. The client process, in this case VRRP, registers interest in tracking these objects and can then be notified when the tracked object changes state.

Examples

In the following example, the tracking process is configured to track the IP routing capability of serial interface 1/0. VRRP on Ethernet interface 0/0 then registers with the tracking process to be informed of any changes to the IP routing state of serial interface 1/0. If the IP state on serial interface 1/0 goes down, then the priority of the VRRP group is reduced by 10.

If both serial interfaces are operational, then Router A will be the master virtual router because it has the higher priority.

However, if IP routing on serial interface 1/0 in Router A fails, then the HSRP group priority will be reduced and Router B will take over as the master virtual router, thus maintaining a default virtual gateway service to hosts on the 10.1.0.0 subnet.

Router A Configuration

!

track 100 interface serial1/0 ip routing

!

interface Ethernet0/0

  ip address 10.1.0.21 255.255.0.0

  vrrp 1 ip 10.1.0.1

  vrrp 1 priority 105

  vrrp 1 track 100 decrement 10

Router B Configuration

!

track 100 interface serial1/0 ip routing

!

interface Ethernet0/0

  ip address 10.1.0.22 255.255.0.0

  vrrp 1 ip 10.1.0.1

  vrrp 1 priority 100

  vrrp 1 track 100 decrement 10

Related Commands

Command	Description
track interface	Configures an interface to be tracked.
track ip route	Tracks the state of an IP route.

Glossary

backup virtual router—One or more VRRP routers that are available to assume the role of forwarding packets if the master virtual router fails.

master virtual router—The VRRP router that is currently responsible for forwarding packets sent to the IP addresses of the virtual router. Usually the master virtual router also functions as the IP address owner.

virtual IP address owner—The VRRP router that owns the IP address of the virtual router. The owner is the router that has the virtual router address as its physical interface address.

virtual router—One or more VRRP routers that form a group. The virtual router acts as the default gateway router for LAN clients. Also known as a VRRP group.

VRRP router—A router that is running VRRP.

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Note Refer to the Internetworking Terms and Acronyms for terms not included in this glossary.

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