Host and service monitoring alert noise can be minimized by configuring hosts with “parents.” By defining parents for your devices, OmniCenter can understand the hierarchy of the network and use that information to isolate outages to the specific devices that are actually causing reachability problems—as opposed to seeing all of the devices that are being affected by the outage as problems in themselves. This is called “root cause detection.” For example, if a switch goes down, and the servers plugged into that switch are configured as “children” of the switch, alert notifications will not be sent for each individual server, but only for the switch that is actually causing the problem. This can greatly reduce alert notification volume during a large network outage.
OmniCenter decides when to send host alerts based on the following logic:
- If a host is down, check to see if the parents of that host are down.
- If any of the parents are up, that host is likely the problem—send a host alert notification for that host.
- If none of the host’s parents are up, that host is likely not the problem—do not send a host alert notification for that host.
- Move up the hierarchy and check to see if any of the grandparents are up—and so on.
OmniCenter cycles through this process until it discovers a parent who is up, or a host that does not have any parents configured. It then sends an alert notification about the first host discovered who has at least one working parent, or does not have any parents configured.
Ensuring that all of your devices have parenting properly configured in OmniCenter also allows the network topology to be displayed visually on the main topology map (Quick Views → Map View → Topology), and the topology map found on the “Topology” tab of the device dashboard for each device.
Parenting can be configured for devices in two places in OmniCenter:
- The “Alerting” device administration page for a device (Edit → Alerting in the Device Dashboard menu). For a single device.
- The “Parent Configuration” page of OmniCenter (Administration → Parenting → Change in the main menu).
Parenting should always be configured from the network perspective of where the OmniCenter server is located on the network.
Be aware that OmniCenter does not continuously scan for parenting changes. The automatic discovery of a device’s parents is a one-time operation that must be initiated manually from its “Alerting” device administration page. Clicking the Auto Discover button in the parenting section of that page causes OmniCenter to send traceroute packets to that host and learn its directly attached parent via the results. However, OmniCenter can only find parents at layer 3, so switches will not generally be autodiscovered as the parents of any devices. Additionally, autoparenting will only find a single parent for each device and can take some time to complete. Using the Auto Discover button will also remove any manual parenting you may have already done for a device.