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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.
Defaults none
Command
Modes
CONFIGURATION
Command
History
Version Description
9.7(0.0) Introduced on the S6000-ON.
8.3.12.0 Introduced on the S4810.
8.4.1.0 Introduced.
Usage
Information
Use this command to create an object that tracks the reachability of an IPv4 route.
In order for a route’s reachability to be tracked, the route must appear as an entry
in the routing table.
A tracked IPv4 route is considered to match an entry in the routing table only if the
exact IPv4 address and prefix length match a table entry. For example, when
configured 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 IPv4 route reachability as a tracked object, the UP/DOWN
state of the tracked route is also determined by the entry of the next-hop address
in the ARP cache. A tracked route is considered to be reachable if there is an ARP
cache entry for the route's next-hop address.
If the next-hop address in the ARP cache ages out for a route tracked for its
reachability, an attempt is made to regenerate the ARP cache entry to if the next-
hop address appears before considering the route DOWN.
Object Tracking
1251