Users Guide

match the routing table entry 10.0.0.0/8. If no route-table entry has the exact IPv4 address and prex length,
the status of the tracked route is considered to be DOWN.
When you congure 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 dierent 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 congured 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 congure 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 notication of a
change in the state of a tracked object is sent when a metric value crosses a congured threshold.
Related Commands
• show track – displays information about tracked objects, including conguration, current state, and
clients which track the object.
• threshold metric – congures the metric threshold used to determine the UP and/or DOWN state of a
tracked route.
• track resolution ip route – congures the protocol-specic resolution value used to scale an IPv4 route
metric.
track ip host reachability
Congure object tracking on the reachability of an IPv4 host.
Syntax
track object-id ip host host-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/ prex-
len
Enter an IPv4 address in dotted decimal format. The valid IPv4 prex lengths are
from /0 to /32.
vrf vrf-name (Optional) You can congure a VPN routing and forwarding (VRF) instance to
specify the virtual routing table to which the tracked route belongs.
Defaults none
Command Modes CONFIGURATION
Command History
Version Description
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S4820T, S4810, S6000, S5000, Z9000, Z9500, IOA, and MXL.
1112
Object Tracking