Check Interface Status (Service Check)

Service Check Category: Interface Checks

Active/Passive: Active

See also Service Check for a general explanation of service checks in Netreo.

Description

See also Monitoring Network Interfaces for additional information about monitoring network interfaces for availability and performance.

This service check is used for monitoring the availability (operational status) of network interfaces on managed devices. It is designed to be used with device templates only. Do not manually add this service check directly to a managed device.

When added to a managed device by a device template, this active service check manages the automatic addition of passive service checks to that device that monitor its individual network interfaces. The active check adds one passive service check for each interface on the active interfaces list for that device. Each passive service check is associated to a specific interface and monitors that interface for its operational status.

Unlike typical service checks, the Check Interface Status active check itself is not displayed in the Services List panel of the Device Dashboard. Only the passive service checks created by this check are displayed there (see image below).

The passive service checks are updated by Netreo each time their associated device is polled for monitoring data (typically every 5 minutes). If the operational status of a monitored interface is not 1, its associated passive check will fail (and enter the CRITICAL state in accordance with its alarm configuration).

Special Considerations

Interface Administration

In order for this check to properly monitor the interfaces of a given managed device, that device's active interface list must be kept properly updated. Netreo updates the active interfaces list for every device it monitors when discovery polls are run (roughly every hour). However, it is advised to manually schedule an immediate discovery poll (using the Debugging Tools menu) for any device to which you have made interface changes so that no gaps in monitoring occur.

Once an interface has a passive check associated with it and is being monitored, it will not be removed from the active interfaces list until that passive check is removed. This is to allow Netreo to continue to monitor interfaces that have become operationally down after a discovery poll occurs and would have normally removed those interfaces from that list.

If an interface currently being monitored is administratively turned off, the passive check for that interface will not be deleted. The result being that the check will still appear in the Services List panel of the Device Dashboard and the Service Checks panel of the Device Administration page, but it will not be updated. The interface will also remain visible on the Performance tab of the Device Dashboard but it will not be polled for, or display, current bandwidth performance data (although historical data may still be seen). If you wish to remove the passive check for an interface that has been administratively turned off, it will need to be manually deleted from the device.

Configuration

The configuration fields listed below are specific to this check. See the Configuration section of the Service Check article for details on configuration options common to all service checks.

Note: Unlike most other service checks, the Check Interface Status check itself is not displayed on the Service Checks panel of the Device Administration page (since it must be used from, and configured within, a device template). Additionally, the passive service checks added by this check (which are displayed) have no configuration options available to the user (they are controlled directly by the configuration of the active check in its device template). Those passive checks display a lock icon in the ACTIONS column of that panel (see image below). Select the lock icon to open and edit the device template that includes the controlling Check Interface Status check.

Configuration Fields

• TYPE- Select a method for filtering which interfaces on the host will be monitored:
  • Interface Name / Description - Looks for matches in the “Interface Description” as displayed in the Current Interfaces panel of the Device Administration page. Enter a regular expression (RLIKE only) or string in the FILTER BY field (if using this option do not leave this field blank). Only interfaces that match the filter will receive passive checks.
  • CDP Layer 2 Adjacency - Only interfaces with CDP Layer 2 connections will receive passive checks and be monitored.
  • Interface Tag - Only interfaces with a matching tag assigned to them will receive passive checks and be monitored. Begin typing a tag name in the FILTER BY TAG field, a list of available matching tags will appear, allowing you to select an appropriate one (if using this option do not leave this field blank). If you type a tag name that does not exists, a new tag will be created and added to the list of existing Netreo tags (remember that you will still need to manually assign that new tag to the appropriate interfaces). Only one tag is allowed per service check. To monitor multiple tags, assign the Check Interface Status check multiple times using this option with different tags.
• INVERT - (Only available when Interface Name / Description is selected for TYPE above.) Leave blank to monitor only interfaces that match the filter entered in the FILTER BY field below. Enter a 1 to monitor only interfaces that don't match the filter.
• SUPPRESS ALERT WHEN ADMINISTRATIVELY DOWN - Switch to Yes to prevent unwanted alerts about interfaces that have been set to administratively down. This option works by preventing passive checks added by this active service check from leaving the OKAY state when their associated interfaces become operationally down if those interfaces have also been set to administratively down. This status is reflected in the Services List panel of the Device Dashboard if a monitored interface goes operationally down.
• FILTER BY - (Only available when Interface Name / Description is selected for TYPE above.) Enter the text to match from the interface name or description to filter the interfaces to monitor. Note: If any advanced filters are being used for the device to filter the interfaces monitored, those filter settings override any filter settings configured in this check. This could potentially add checks to interfaces that are admin or operationally down, resulting in alerts for those interfaces. See Monitoring Network Interfaces for more information.
• FILTER BY TAG - (Only available when Interface Tag is selected for TYPE above.) Enter the interface tag to match to filter the interfaces to monitor. A list of existing tags appears as you type.

Removing This Check

If this service check is deleted from a device template, it will automatically delete all of the passive service checks added by it to any devices affected by that template, except as noted below.

A passive service check added by the Check Interface Status check will not be deleted if its associated interface "goes away" (index shuffling, removed from the all interfaces list, etc.). This is because, when this happens, the Check Interface Status check can no longer associate the passive service check with the lost interface that it was monitoring, and so becomes unable to remove the passive check. Any passive check that permanently loses its association to its interface will need to be manually removed.