Administrator Guide

A tracked route matches a route in the routing table only if the exact address and prefix length match an entry in the routing table. 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 address and prefix length, the tracked route is considered to be DOWN.
In addition to the entry of a route in the routing table, you can configure how the status of a route is tracked in either the following ways:
• By the reachability of the route's next-hop router.
• By comparing the UP or DOWN threshold for a route’s metric with current entries in the route table.
Track a Metric Threshold
If you configure a metric threshold to track a route, the UP/DOWN state of the tracked route is determined by the current metric for the
route entered in the routing table.
To provide a common tracking interface for different clients, route metrics are scaled in the range from 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 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.
The UP and DOWN thresholds are user-configurable for each tracked route. 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.
The tracking process uses a protocol-specific resolution value to convert the actual metric in the routing table to a scaled metric in the
range from 0 to 255. The resolution value is user-configurable and calculates the scaled metric by dividing a route's cost by the resolution
value set for the route type:
• For intermediate system to intermediate system (ISIS), you can set the resolution in the range from 1 to 1000, where the default is 10.
• For OSPF, you can set the resolution in the range from 1 to 1592, where the default is 1.
• The resolution value used to map static routes is not configurable. By default, Dell Networking OS assigns a metric of 0 to static
routes.
• The resolution value used to map router information protocol (RIP) routes is not configurable. The RIP hop-count is automatically
multiplied by 16 to scale it; a RIP metric of 16 (unreachable) scales to 256, which considers the route to be DOWN. For example, to
configure object tracking for a RIP route to be considered UP only if the RIP hop count is less than or equal to 4, you would configure
the UP threshold to be 64 (4 x 16) and the DOWN threshold to be 65.
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 65535.
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]}
Valid delay times are from 0 to 180 seconds.
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Object Tracking