Administrator Guide

Configuring track reachability refresh interval
If there is no entry in ARP table or if the next-hop address in the ARP cache ages out for a route tracked for its reachability, an
attempt is made to check if the next-hop address is reachable after a certain refresh interval to see if the next-hop address
appear in the ARP cache before considering it as DOWN.
You can change the refresh interval for which the next-hop address is checked. The default refresh interval is 60 seconds. The
object tracking is done after the default refresh interval everytime and whenever there is a change in reachability state, the
next-hop will be considered as DOWN. The default interval is changed using the track reachability refresh command.
You can disable the track reachability feature by setting the refresh interval to 0.
To change the refresh interval for tracking an IPv4 or IPv6 route, use the following command.
Change the reachability refresh interval for tracking of an IPv4 or IPv6 route.
CONFIGURATION mode
track reachability refresh interval
The refresh interval range is from 0 to 60 seconds. The default is 60 seconds.
The following example shows how to change the refresh interval for tracking the reachability of the next-hop:
DellEMC#configure
DellEMC(conf)#track reachability refresh 20
For example, consider that the next-hop address is changed and the track reachability is checked after the set refresh interval
(20 seconds). If the reachability to the next-hop address is failed, the system displays the following log stating that the track
object state is changed from UP to DOWN.
Sep 28 11:08:57 %STKUNIT1-M:CP %OTM-6-STATE: Object 2 state transition from Up to Down.
Set Tracking Delays
You can configure an optional UP and/or DOWN timer for each tracked object to set the time delay before a change in the state
of a tracked object is communicated to clients. The configured time delay starts when the state changes from UP to DOWN or
the opposite way.
If the state of an object changes back to its former UP/DOWN state before the timer expires, the timer is cancelled and the
client is not notified. If the timer expires and an object’s state has changed, a notification is sent to the client. For example, if
the DOWN timer is running when an interface goes down and comes back up, the DOWN timer is cancelled and the client is not
notified of the event.
If you do not configure a delay, a notification is sent when a change in the state of a tracked object is detected. The time delay
in communicating a state change is specified in seconds.
VRRP Object Tracking
As a client, VRRP can track up to 20 objects (including route entries, and Layer 2 and Layer 3 interfaces) in addition to the 12
tracked interfaces supported for each VRRP group.
You can assign a unique priority-cost value from 1 to 254 to each tracked VRRP object or group interface. The priority cost is
subtracted from the VRRP group priority if a tracked VRRP object is in a DOWN state. If a VRRP group router acts as owner-
master, the run-time VRRP group priority remains fixed at 255 and changes in the state of a tracked object have no effect.
NOTE:
In VRRP object tracking, the sum of the priority costs for all tracked objects and interfaces cannot equal or exceed
the priority of the VRRP group.
Object Tracking Configuration
You can configure three types of object tracking for a client.
● Track Layer 2 Interfaces
● Track Layer 3 Interfaces
● Track IPv4 and IPv6 Routes
Object Tracking
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