(For a short video about this topic, click here.)
A device template is a collection of preconfigured OmniCenter device monitoring settings that can be used to automatically configure how a given device is monitored by OmniCenter.
The OmniCenter device template system is designed to allow multiple device templates, with different groups of settings, to work together to apply the correct settings to each device in your network based on one or more of the following factors: desired global settings, type of device, applications running on a device (subtype), what site a device is in, what category a device is in, and what functional group a device is in.
By default, OmniCenter tries to automatically configure the monitoring settings for all of the devices it discovers by using a combination of device templates. Only very rarely will you want to configure a monitoring setting on an individual device manually.
Device templates make managing the administration of monitoring settings for managed devices much easier (especially for larger networks), and ensure that the correct settings are applied consistently across your network.
The following monitoring settings can be automatically configured for a device using device templates:
- Authentication Details
- Host Alert Contacts
- Service Checks
- Threshold Checks
- Logging Rules
- Device Configuration Management Rules
Any monitoring settings applied to a device by a device template will override the corresponding settings found in the administration view of the device dashboard for that device. Device template settings are applied to a device every time a discovery poll is performed on that device.
OmniCenter ships with a default pair of preconfigured device templates that cover the basics of monitoring for most devices. These are the Default and Windows Default templates, and can be modified to suit your environment as necessary. You may also create as many additional device templates as you require.
A new device template is initially empty (and will do nothing, even if applied to a device). Specific individual settings (of the types indicated above) must then be added to it to give it functionality. This means that any given device template may include or omit (at the user’s discretion) any or all of the above device monitoring settings. This allows you to construct device templates with any combination of settings desired (the value of doing this is explained later).
Device templates apply their settings to devices in a strict linear order, dictated by OmniCenter’s device template hierarchy (see table below). Settings from templates later in the order override any conflicting settings from templates earlier in the order. To provide flexibility for individual deployments, any user-created device template may be assigned to any of the hierarchy levels (except global—which comes with its own unique device templates).
The device template hierarchy is arranged in the following order, from first applied to last applied (settings from higher number templates override settings from lower number templates).
|Hierarchy Level||Order Applied||Description|
|Global||1||Applied globally to every managed device (unless template use is turned off for a device). Only two templates exist that can be used at this level, Default and Windows Default. Depending on the type of device, one of these two templates is always used. They include a default host alert contact (based on the default email address provided to OmniCenter) and some basic service and threshold checks. Always applied first.|
|Device Type||2||If a device type in OmniCenter has a device template assigned to it, all monitored devices of that type will receive settings from that template.|
|Device Subtype||3||If a device subtype in OmniCenter has a device template assigned to it, all monitored devices of that subtype will receive settings from that template. Since a device may have multiple subtypes assigned to it, multiple templates may apply settings at this level. The order in which subtype templates are applied is alphanumerical by subtype name.|
|Site||4||If a site device group in OmniCenter has a device template assigned to it, all monitored devices assigned to that site will receive settings from that template.|
|Category||5||If a category device group in OmniCenter has a device template assigned to it, all monitored devices assigned to that category will receive settings from that template.|
|Functional Group||6||If a functional group has a device template assigned to it, all monitored devices assigned to that functional group will receive settings from that template. Since a device may be assigned to multiple functional groups, multiple templates may apply settings at this level. The order in which functional group templates are applied is managed in Device Template Administration.|
|Device||7||This is a template assigned directly to an individual device. Always the last template applied. This template wins any conflict, so use with extreme caution (should rarely be used).|
As you can see from the table above, it is not necessarily the case that all device templates in the hierarchy are applied to all devices. Only the global and device-level templates are always applied.
Individual settings added to a device template are applied to devices in a “cascading” manner. This means that if a given template includes a setting—but other templates applied later in the order omit that setting—the setting from the earlier template will cascade across the later templates and still be applied to the target device. In this way, different device templates can each apply specific individual settings to devices simultaneously without interfering with each other. However, if in the same scenario above, multiple templates include the same setting type while some omit it, the setting from the last template applied to the device is the one that will be used.
So, settings will only cascade across other device templates until another template also includes that setting. The only device monitoring setting this doesn’t apply to is host alert contacts. Any host alert contacts configured in device administration or included in device templates will all be added to the device cumulatively. They do not override each other.
If all of the templates applied to a device omit a particular setting, then that setting as configured in the device administration of the respective device will be used (since there is no template setting to override it). However, those settings can still be overridden by future device templates that do include them. The only way to prevent device templates from overriding device-level settings is to either omit the setting from any device templates that may be applied to that device or to turn off device template usage completely for that device (recommended only in unusual circumstances).
To prevent configuration errors, device templates are designed in such a way that any setting included in a template that is not compatible (or not applicable) with a device the template is applied to, will simply be ignored by that device. This provides a great deal of flexibility for administrators when designing a device template strategy, as settings for entirely different kinds of devices may be included in the same template.
Example of Device Template Usage
It’s important to understand where in the hierarchy a particular setting from a device template is applied—and whether it will override another template’s setting, or itself be overridden. To see how all of this works, let’s look at the example below.
Imagine a wide area network composed of a San Francisco location (with a large number routers) and a remote Beijing location (with a handful of remote routers in different parts of the city and a single higher-performing core router, “Beijing-Core-01,” at the headquarters location).
We want to monitor latency for all of the routers on the network. Now, since we’ll be monitoring the network from the San Francisco location, we know that latency for the majority of our routers will be low, as most of them are co-located with our monitoring center. The remaining routers, in our Beijing location, will have significantly higher latency—except for one, the Beijing-Core-01 device, which consistently performs significantly better than the other routers in the region, which justifies it getting its own settings.
Manually adding latency threshold checks to all of these devices individually would be quite tedious, not to mention difficult to manage and scale. This is where templates come in. To greatly reduce the work involved, we’re going to specify the differences between these devices, and what we want from them, using just three device templates. All of the routers on this network will then automatically inherit the correct monitoring settings from the templates with no further effort from us.
To start, we’ll edit the latency threshold check configuration of the existing Default device template (applied to all managed devices) to have a setting of 200 ms. This will handle the bulk of our routers.
Next, we’ll create a new device template named “Beijing-Devices” and include a latency threshold check configured with a setting of 800 ms. We’ll assign this template to the Beijing site (to which our Beijing routers should already be assigned).
Finally, we’ll create a another new device template named “Remote-Core Routers” and include a latency threshold check configured with a setting of 400 ms. This last template we’ll assign directly to the one core router in our Beijing headquarters location. That’s all there is to it. Every router will now automatically inherit the correct settings from the templates.
To be more specific: All managed devices on the network now have a latency threshold check applied globally from the Default template. Since the template hierarchy applies site-level device templates after the global level, all of the devices assigned to the Beijing site have that setting overridden with the 400 ms setting from the “Beijing-Devices” template. Now, even though the “Beijing-Core-01” router is also in the Beijing site, we applied the “Remote-Core Routers” template directly to that device. Since device-level templates are always the last to be applied in the hierarchy, the “Remote-Core Routers” template setting is used for the “Beijing-Core-01” device.
Additionally, as an example of how the device template settings cascade, if a device template named “Cisco Routers” is assigned to the “Cisco Router” device type, and had a CPU utilization threshold check with a setting of 90% included, but the aforementioned Default, “Beijing-Devices,” and “Remote-Core Routers” templates did not, that setting would cascade across the later templates—without interference—and be applied to the “Beijing-Core-01” device (because it is, in fact, a Cisco router). Remember, because this template was assigned to a device type, these settings would also be applied to every other managed device of this type on the network.
Preconfigured Device Templates
OmniCenter ships with two preconfigured device templates to provide basic monitoring settings for all of the managed devices in your network. These are the Default and Windows Default device templates. They provide starting points for implementing your overall device template strategy.
The “Default” Template
The Default device template is unique and is created by OmniCenter during deployment. There is only ever one Default template, and it is always only assigned to the Global hierarchy level.
This template may be edited to suit your environment. It cannot, however, be renamed or deleted. Be aware that, even if you choose not to modify it, it is always applied. Any device monitoring settings that you may manually apply to an individual device, that conflict with this template, will be overridden (unless template use is turned off for that device). This template is the very first device template applied in the template hierarchy.
(Since the Default template is always assigned, you should not attempt to assign it to any of the other hierarchy levels.)
The “Windows Default” Template
The Windows Default device template is created by OmniCenter during deployment. Although its name uses the word “default” in it, this template is simply a normal device template automatically assigned to the “Windows Server WMI” device type by OmniCenter. It is provided for your convenience, and provides a starting point to a device template strategy for Microsoft Windows-based devices.
Unlike the Default template, this template can be deleted. However, if this is done accidentally, it can always be downloaded again from the Netreo cloud libraries.