The Enhanced Object Tracking feature provides complete separation between the objects to be tracked and the action to be taken by a client when a tracked object changes. Thus, several clients such as HSRP, VRRP, or GLPB can register their interest with the tracking process, track the same object, and each take different action when the object changes.

Each tracked object is identified by a unique number that is specified on the tracking CLI. Client processes 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.

You can configure a combination of tracked objects in a list and a flexible method for combining objects using Boolean logic. This functionality includes the following capabilities:

• Threshold––The tracked list can be configured to use a weight or percentage threshold to measure the state of the list. Each object in a tracked list can be assigned a threshold weight. The state of the tracked list is determined by whether the threshold has been met.
• Boolean "and" function––When a tracked list has been assigned a Boolean "and" function, each object defined within a subset must be in an up state so that the tracked object can become up.
• Boolean "or" function––When the tracked list has been assigned a Boolean "or" function, at least one object defined within a subset must be in an up state so that the tracked object can become up.

As of Cisco IOS Release 15.1(3)T, 15.1(1)S and 12.2(50)SY a maximum of 1000 objects can be tracked. Although 1000 tracked objects can be configured, each tracked object uses CPU resources. The amount of available CPU resources on a router depends on variables such as traffic load and how other protocols are configured and run. The ability to use 1000 tracked objects depends on the available CPU. Testing should be conducted on site to ensure that the service works under the specific site traffic conditions.

An IP-routing object is considered up when the following criteria exist:

• IP routing is enabled and active on the interface.
• The interface line-protocol state is up.
• The interface IP address is known. The IP address is configured or received through Dynamic Host Configuration Protocol (DHCP) or IP Control Protocol (IPCP) negotiation.

Interface IP routing will go down when one of the following criteria exists:

• IP routing is disabled globally.
• The interface line-protocol state is down.
• The interface IP address is unknown. The IP address is not configured or received through DHCP or IPCP negotiation.

Tracking the IP-routing state of an interface using the track interface ip routing command can be more useful in some situations than just tracking the line-protocol state using the track interface line-protocol command, especially on interfaces for which IP addresses are negotiated. For example, on a serial interface that uses the PPP, the line protocol could be up (link control protocol [LCP] negotiated successfully), but IP could be down (IPCP negotiation failed).

The track interface ip routing command supports the tracking of an interface with an IP address acquired through any of the following methods:

• Conventional IP address configuration
• PPP/IPCP
• DHCP
• Unnumbered interface

You can configure Enhanced Object Tracking to consider the carrier-delay timer when tracking the IP-routing state of an interface by using the carrier-delay command in tracking configuration mode.

The track ip route command enables tracking of a route in the routing table. If a route exists in the table, the metric value is converted into a number. To provide a common interface to tracking clients, normalize route metric values to the range from 0 to 255, where 0 is connected and 255 is inaccessible. Scaled metrics can be tracked by setting thresholds. Up and down state notification occurs when the thresholds are crossed. The resulting value is compared against threshold values to determine the tracking state as follows:

• State is up if the scaled metric for that route is less than or equal to the up threshold.
• State is down if the scaled metric for that route is greater than or equal to the down threshold.

Tracking uses a per-protocol configurable resolution value to convert the real metric to the scaled metric. The table below shows the default values used for the conversion. You can use the track resolution command to change the metric resolution default values.

For example, a change in 10 in an IS-IS metric results in a change of 1 in the scaled metric. The default resolutions are designed so that approximately one 2-Mbps link in the path will give a scaled metric of 255.

Scaling the very large metric ranges of EIGRP and IS-IS to a 0 to 255 range is a compromise. The default resolutions will cause the scaled metric to exceed the maximum limit with a 2-Mb/s link. However, this scaling allows a distinction between a route consisting of three Fast-Ethernet links and a route consisting of four Fast-Ethernet links.

Object tracking of IP Service Level Agreements (SLAs) operations allows tracking clients to track the output from IP SLAs objects and use the provided information to trigger an action.

Cisco IOS IP SLAs is a network performance measurement and diagnostics tool that uses active monitoring. Active monitoring is the generation of traffic in a reliable and predictable manner to measure network performance. Cisco IOS software uses IP SLAs to collect real-time metrics such as response time, network resource availability, application performance, jitter (interpacket delay variance), connect time, throughput, and packet loss.

These metrics can be used for troubleshooting, for proactive analysis before problems occur, and for designing network topologies.

Every IP SLAs operation maintains an operation return-code value. This return code is interpreted by the tracking process. The return code can return OK, OverThreshold, and several other return codes. Different operations can have different return-code values, so only values common to all operation types are used.

Two aspects of an IP SLAs operation can be tracked: state and reachability. The difference between these aspects is the acceptance of the OverThreshold return code. The table below shows the state and reachability aspects of IP SLAs operations that can be tracked.

Enhanced Object Tracking (EOT) is now integrated with Embedded Event Manager (EEM) to allow EEM to report on status change of a tracked object and to allow EOT to track EEM objects. A new type of tracking object--a stub object--is created. The stub object can be modified by an external process through a defined Application Programming Interface (API). See the Embedded Event Manager Overview document in the Cisco IOSNetwork Management Configuration Guide for more information on how EOT works with EEM.

The EOT Support for Carrier Delay feature enables Enhanced Object Tracking (EOT) to consider the carrier-delay timer when tracking the status of an interface.

If a link fails, by default there is a two-second timer that must expire before an interface and the associated routes are declared as being down. If a link goes down and comes back up before the carrier delay timer expires, the down state is effectively filtered, and the rest of the software on the switch is not aware that a link-down event occurred. You can configure the carrier-delay seconds command in interface configuration mode to extend the timer up to 60 seconds.

When EOT is configured on an interface, the tracking may detect the interface is down before a configured carrier-delay timer has expired. This is because EOT looks at the interface state and does not consider the carrier delay timer. Use the carrier-delay command in tracking configuration mode to enable tracking to consider the carrier-delay timer configured on an interface.

The Enhanced Object Tracking Support for Mobile IP feature enables EOT to monitor the presence of Home Agent, Packet Data Serving Node (PDSN), or Gateway GPRS Support Node (GGSN) traffic on a router for mobile wireless applications.

When a redundant pair of Home Agents running HSRP between them loses connectivity, both HSRP nodes become active. Once the connectivity is restored between the two nodes, a graceful way is needed to restore proper HSRP states without losing Home Agent bindings. During the time of no connectivity, one of the nodes will continue to process Home Agent, GGSN, or PDSN traffic while the other will not. The node that continues to process traffic needs to remain active once connectivity is restored. To ensure that the active node remains in the active state, the priority of the HSRP group member that does not process Home Agent traffic is reduced. Reducing the priority of the node that is not processing Home Agent traffic ensures that this node will become the standby after connectivity is restored. When connectivity is restored, the normal Home Agent state synchronization will get all bindings back into the inactive node and, depending on the preempt configuration, it may switch over again. This state synchronization ensures that no Mobile IP, GGSN, or PDSN bindings are lost.

For more information on configuring Mobile IP services, see the following Cisco IOS configuration guides:

• Cisco IOS Mobile Wireless Home Agent Configuration Guide
• Cisco IOS Mobile Wireless Gateway GPRS Support Node Configuration Guide
• Cisco IOS Mobile Wireless Packet Data Serving Node Configuration Guide
• Cisco IOS IP Mobility Configuration Guide

• Increases the availability and speed of recovery of a network.
• Decreases the number of network outages and their duration.
• Enables client processes such as VRRP and GLBP to track objects individually or as a list of objects. Prior to the introduction of this functionality, the tracking process was embedded within HSRP.

1.    enable

2.    configure terminal

3.    track timer interface {seconds | msec milliseconds}

4.    track object-number interface type number line-protocol

5.    carrier-delay

6.    delay {up seconds [down [seconds] | [up seconds] down seconds]}

7.    end

8.    show track object-number

Router# show track 3

Track 3
   Interface Ethernet0/1 line-protocol
   Line protocol is Up
     1 change, last change 00:00:05
   Tracked by:
     HSRP Ethernet0/3 1

1.    enable

2.    configure terminal

3.    track timer interface {seconds | msec milliseconds}

4.    track object-number interface type number ip routing

5.    carrier-delay

6.    delay {up seconds [down seconds] | [up seconds] down seconds}

7.    end

8.    show track object-number

Router# show track 1

Track 1
   Interface Ethernet0/1 ip routing
   IP routing is Up
     1 change, last change 00:01:08
   Tracked by:
     HSRP Ethernet0/3 1

1.    enable

2.    configure terminal

3.    track timer ip route {seconds | msec milliseconds}

4.    track object-number ip route ip-address/prefix-length reachability

5.    delay {up seconds [down seconds] | [up seconds] down seconds}

6.    ip vrf vrf-name

7.    end

8.    show track object-number

Router# show track 4

Track 4
   IP route 10.16.0.0 255.255.0.0 reachability
   Reachability is Up (RIP)
     1 change, last change 00:02:04
   First-hop interface is Ethernet0/1
   Tracked by:
     HSRP Ethernet0/3 1

1.    enable

2.    configure terminal

3.    track timer ip route {seconds | msec milliseconds}

4.    track resolution ip route {eigrp | isis | ospf | static} resolution-value

5.    track object-number ip route ip-address/prefix-length metric threshold

6.    delay {up seconds [down seconds] | [up seconds] down seconds}

7.    ip vrf vrf-name

8.    threshold metric {up number [down number] | down number [up number ]}

9.    end

10.    show track object-number

Router# show track 6

Track 6
   IP route 10.16.0.0 255.255.0.0 metric threshold
   Metric threshold is Up (RIP/6/102)
     1 change, last change 00:00:08
   Metric threshold down 255 up 254
   First-hop interface is Ethernet0/1
   Tracked by:
     HSRP Ethernet0/3 1

1.    enable

2.    configure terminal

3.    track object-number ip sla operation-number state

4.    delay {up seconds [down seconds | [up seconds] down seconds}

5.    end

6.    show track object-number

Router# show track 2

Track 2
   IP SLA 1 state
   State is Down
     1 change, last change 00:00:47
   Latest operation return code: over threshold
   Latest RTT (millisecs) 4
   Tracked by:
     HSRP Ethernet0/1 3

1.    enable

2.    configure terminal

3.    track object-number ip sla operation-number reachability

4.    delay {up seconds [down seconds] | [up seconds] downseconds}

5.    end

6.    show track object-number

Router# show track 3

Track 3
   IP SLA 1 reachability
   Reachability is Up
     1 change, last change 00:00:47
   Latest operation return code: over threshold
   Latest RTT (millisecs) 4
   Tracked by:
     HSRP Ethernet0/1 3

Before You Begin

An object must exist before it can be added to a tracked list.

Note	The “not” operator is specified for one or more objects and negates the state of the object.

1.    enable

2.    configure terminal

3.    track track-number list boolean {and | or}

4.    object object-number [not]

5.    delay {up seconds [down seconds] | [up seconds] down seconds}

6.    end

Before You Begin

An object must exist before it can be added to a tracked list.

Note	You cannot use the Boolean “not” operator in a weight or percentage threshold list.

1.    enable

2.    configure terminal

3.    track track-number list threshold weight

4.    object object-number [weight weight-number]

5.    threshold weight {up number down number | up number | down number}

6.    delay {up seconds [down seconds] | [up seconds] down seconds}

7.    end

Perform this task to configure a tracked list of objects, to specify that a percentage will be used as the threshold, and to specify a percentage for each object in the list. A tracked list contains one or more objects. Enhanced object tracking uses the threshold percentage to determine the state of the list by comparing the assigned percentage of each object to the list.

You may also configure a tracked list state to be measured using a Boolean calculation or threshold weight. See the Configuring a Tracked List and Boolean Expression section and the Configuring a Tracked List and Threshold Weight section.

Note	You cannot use the Boolean “not” operator in a weight or percentage threshold list.

1.    enable

2.    configure terminal

3.    track track-number list threshold percentage

4.    object object-number

5.    threshold percentage {up number [down number ] | down number [up number]}

6.    delay {up seconds [down seconds] | [up seconds] down seconds}

7.    end

1.    enable

2.    configure terminal

3.    track track-number

4.    default {delay | object object-number | threshold percentage}

5.    end

1.    enable

2.    configure terminal

3.    track track-number application home-agent

4.    exit

5.    track track-number application pdsn

6.    exit

7.    track track-number application ggsn

8.    end