About Object Tracking
Object tracking allows you to track specific objects on the device, such as the interface line protocol state, IP routing, and route reachability, and to take action when the tracked object’s state changes. This feature allows you to increase the availability of the network and shorten recovery time if an object state goes down.
Object Tracking Overview
Object tracking allows you to track specific objects on the device, such as the interface line protocol state, IP routing, and route reachability, and to take action when the state of the tracked object changes. This feature allows you to increase the availability of the network and shorten recovery time if an object state goes down.
The object tracking feature allows you to create a tracked object that multiple clients can use to modify the client behavior when a tracked object changes. Several clients register their interest with the tracking process, track the same object, and take different actions when the object state changes.
Clients include the following features:
Embedded Event Manager (EEM)
Hot Standby Redundancy Protocol (HSRP)
Virtual port channel (vPC)
Virtual Router Redundancy Protocol (VRRP) and VRRPv3
The object tracking monitors the status of the tracked objects and communicates any changes made to interested clients. Each tracked object is identified by a unique number that clients can use to configure the action to take when a tracked object changes state.
Cisco NX-OS tracks the following object types:
Interface line protocol state—Tracks whether the line protocol state is up or down.
Interface IP routing state—Tracks whether the interface has an IPv4 or IPv6 address and if IPv4 or IPv6 routing is enabled and active.
IP route reachability—Tracks whether an IPv4 or IPv6 route exists and is reachable from the local device.
For example, you can configure HSRP to track the line protocol of the interface that connects one of the redundant routers to the rest of the network. If that link protocol goes down, you can modify the priority of the affected HSRP router and cause a switchover to a backup router that has better network connectivity.
Object Track List
An object track list allows you to track the combined states of multiple objects. Object track lists support the following capabilities:
Boolean "and" function—Each object defined within the track list must be in an up state so that the track list object can become up.
Boolean "or" function—At least one object defined within the track list must be in an up state so that the tracked object can become up.
Threshold percentage—The percentage of up objects in the tracked list must be greater than the configured up threshold for the tracked list to be in the up state. If the percentage of down objects in the tracked list is above the configured track list down threshold, the tracked list is marked as down.
Threshold weight—Assign a weight value to each object in the tracked list and a weight threshold for the track list. If the combined weights of all up objects exceed the track list weight up threshold, the track list is in an up state. If the combined weights of all the down objects exceed the track list weight down threshold, the track list is in the down state.
Other entities, such as virtual port channels (vPCs) can use an object track list to modify the state of a vPC based on the state of the multiple peer links that create the vPC. See the Cisco Nexus 3400-S NX-OS Interfaces Configuration Guide for more information on vPCs.
See the Configuring an Object Track List with a Boolean Expression section for more information on track lists.
Object tracking supports high availability through stateful restarts. A stateful restart occurs when the object tracking process crashes. Object tracking also supports a stateful switchover on a dual-supervisor system. Cisco NX-OS applies the runtime configuration after the switchover.
You can also use object tracking to modify the behavior of a client to improve overall network availability.
Object tracking supports virtual routing and forwarding (VRF) instances. By default, Cisco NX-OS tracks the route reachability state of objects in the default VRF. If you want to track objects in another VRF, you must configure the object to be a member of that VRF. See Configuring Object Tracking for a Nondefault VRF.