Device Dependency

Note: The Device Dependency link is only visible to department users, not admin group users or a superusers.

In a networked environment, switches and routers are often the physical gateways that provide access to other network devices. If critical parent devices are unavailable, monitoring can be impeded for devices that are accessed through the parents. To distinguish between devices that are genuinely in a CRITICAL state and those that are UNREACHABLE because of a problem with one or more parent devices, you can create device dependencies.

A device dependency is a parent-child relationship between monitored devices. A single parent can have multiple children, and a single child can have multiple parents. Device dependencies are cascading. If A is a child of B, and B is a child of C, it is only necessary to configure A as a child of B and B as a child of C. Traverse automatically recognizes the dependency between A and C.

If a device is tested and the result is CRITICAL (for all thresholds), UNKNOWN, or FAILED, some additional processing is used to determine if the device is reachable. If Traverse cannot access any of the child's parent devices, the child is considered UNREACHABLE.

Testing if a Device is Reachable

A current packet loss test is examined for the device.

• If such a test exists and packet loss is not 100%, the device is considered reachable.
• If no packet loss test exists, all immediate parent devices are examined. If the device has no parents, it is considered reachable and the result of the test is the measured value. If all parents have a current packet loss test which was measured at 100%, the device is considered unreachable.
• If no packet loss test exists for the parent, or no recent test result is found for an existing packet loss test, the child device is considered reachable and the result of the test is the measured value.

Dependency Restrictions

Device dependencies must conform to the following rules:

1. Circular dependency is not allowed. For example, if Device A depends on Device B depends on Device C, you cannot configure Device C to depend on Device A.
2. Parent and child devices must belong to the same location.

To enable a device dependency:

1. Navigate to the Administration > Devices page.
2. Select the Device Dependency link. The Update Device Dependency page displays.

   Note: This same page displays after completing the Create Device page, if you check the Create Device Dependency After Creating This Device checkbox.

3. Select one or more devices in the All Devices List. Existing dependencies display in the Depends On list.
4. Select devices in the Does Not Depend On list.
5. Click the >> button to selected devices to the Depends On list.
6. Click the Update Dependency button.