Concept Guide

Track 105
IPv6 route 1234::/64 reachability
Description: Headquarters
Reachability is Down (route not in route table)
2 changes, last change 00:03:03
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.
Tracking a Metric Threshold
Use the following commands to configure object tracking on the metric threshold of an IPv4 or IPv6 route.
To remove object tracking, use the no track object-id command.
1. (Optional) Reconfigure the default resolution value used by the specified protocol to scale the metric for IPv4 or IPv6
routes.
CONFIGURATION mode
track resolution {ip route | ipv6 route} {isis resolution-value | ospf resolution-value}
The range of resolution values is:
● ISIS routes - 1 to 1000. The default is 1.
● OSPF routes - 1 to 1592. The efault is 1.
2. Configure object tracking on the metric of an IPv4 or IPv6 route.
CONFIGURATION mode
track object-id {ip route ip-address/prefix-len | ipv6 route ipv6-address/prefix-len}
metric threshold [vrf vrf-name]
Valid object IDs are from 1 to 500.
Enter an IPv4 address in dotted decimal format. Valid IPv4 prefix lengths are from /0 to /32.
Enter an IPv6 address in X:X:X:X::X format. Valid IPv6 prefix lengths are from /0 to /128.
(Optional) E-Series only: For an IPv4 route, you can enter a VRF name.
3. (Optional) Configure the time delay used before communicating a change in the UP and/or DOWN status of a tracked route.
OBJECT TRACKING mode
delay {[up seconds] [down seconds]}
Object Tracking
623