Users Guide

as a tracked route, 10.0.0.0/24 does not match the routing table entry 10.0.0.0/8. If no
route-table entry has the exact IPv4 address and prefix length, the status of the tracked
route is considered to be DOWN.
When you configure the threshold of an IPv4 route metric as a tracked object, the UP/
DOWN state of the tracked route is also determined by the current metric for the route
in the routing table.
To provide a common tracking interface for different clients, route metrics are scaled in
the range 0 to 255, where 0 is connected and 255 is inaccessible. The scaled metric
value communicated to a client always considers a lower value to have priority over a
higher value. The resulting scaled value is compared against the configured threshold
values to determine the state of a tracked route as follows:
• If the scaled metric for a route entry is less than or equal to the UP threshold, the
state of a route is UP.
• If the scaled metric for a route is greater than or equal to the DOWN threshold or
the route is not entered in the routing table, the state of a route is DOWN.
You configure the UP and DOWN thresholds for each tracked route by using the
threshold metric command. The default UP threshold is 254; the default DOWN
threshold is 255. The notification of a change in the state of a tracked object is sent
when a metric value crosses a configured threshold.
Related
Commands
• show track – display information about tracked objects, including configuration,
current state, and clients which track the object.
• threshold metric – configure the metric threshold used to determine the UP
and/or DOWN state of a tracked route.
• track resolution ip route – configure the protocol-specific resolution value used
to scale an IPv4 route metric.
track ip route reachability
Configure object tracking on the reachability of an IPv4 route.
Syntax
track object-id ip route ip-address/prefix-len reachability [vrf
vrf-name]
To return to the default setting, use the no track object-id command.
Parameters
object-id Enter the ID number of the tracked object. The range is 1 to 500.
ip-address/
prefix-len
Enter an IPv4 address in dotted decimal format. The valid IPv4
prefix lengths are from /0 to /32.
vrf vrf-name (Optional) E-Series only: You can configure a VPN routing and
forwarding (VRF) instance to specify the virtual routing table to
which the tracked route belongs.
Object Tracking 1352