Device Classes

A device class is the type of a device — Router, Switch, Firewall, Access Point, Server, Storage, and so on. Every device in your inventory belongs to a class, and that class is what tells GridNMS how to monitor it: which monitoring packs run, what data is collected, and which tabs appear on the device’s detail page.

Classes are arranged in a hierarchy, and settings flow down it. Get your classes right once, and every device of that type is configured automatically — no per-device setup.

The Device Classes page: pick a class from the tree on the left, then configure its settings, devices, packs, and interfaces on the right.

What classes are for

A class does three jobs:

1. Decides what gets monitored. Each class has one or more monitoring packs attached. A device picks up every pack on its class — and every pack on the classes above it — so a switch collects port and interface data, while a server-style device collects CPU, memory, and disk.
2. Holds shared settings. SNMP and SSH credentials, the reachability check method, and poll intervals can all be set once on a class and applied to every device in it.
3. Shapes the device page. The packs on a class also define the detail tabs you see when you open a device, so all devices of the same type present a consistent layout.

The class hierarchy

Classes form a tree. At the very top is a built-in All Classes root (marked with a lock icon) — these are the global defaults that every class and device inherits unless something below overrides them.

Below the root sit your top-level categories (Router, Switch, Server, and so on), and you can nest more specific classes underneath them. A typical hierarchy:

All Classes              (system defaults — inherited by everything)
├── Router
│   └── Cisco Router     (inherits everything from Router, plus its own)
├── Switch
├── Firewall
├── Access Point
├── Server
│   ├── Linux
│   └── Windows
└── Storage

How inheritance works

A child class inherits everything from its parents and can add to or override it:

• Packs add up. A Cisco Router that sits under Router collects both the generic Router packs and any Cisco-specific packs attached directly to it. Children never lose their parent’s monitoring — they only gain more.
• Settings fall through. A credential or poll interval left blank on a class falls through to its parent, and ultimately to the All Classes defaults. Set a value at any level to override what’s above it.

This “most specific wins” rule means you can set a community string once at the top and override it only where a particular family of devices differs.

Note

The order of priority, from strongest to weakest, is: device-level setting → class setting → parent class → All Classes defaults. A value set directly on a device always wins. See Overriding Device Details for the device-level layer.

Creating and editing a class

To add a class:

1. Open Device Classes.
2. Click New Class.
3. Fill in the dialog:

   Field	What it does
   Name	The display name (e.g. Core Switch, Edge Firewall).
   Parent Class	The class this one sits under. Leave it as None to make a top-level category.
   Description	An optional note describing what the class is for.
   Layer	An optional network layer (2 or 3). Topology and map views use it to group devices correctly.

4. Click Create.

To change a class later, select it in the tree and click Edit. To remove one, select it and click Delete.

Caution

Deleting a class does not delete its devices, but those devices lose their class assignment — which means they stop inheriting that class’s packs and settings until you reassign them. The built-in All Classes root cannot be edited or deleted.

Assigning monitoring packs to a class

This is how you turn on monitoring for a whole device type at once.

1. Select the class in the tree.
2. Open the Packs tab.
3. Click Apply Pack.
4. Choose a pack from the list of installed packs and click Apply.

Every device in that class — and every device in its child classes — immediately inherits the pack and begins collecting its data on the next poll cycle. Packs already applied are marked so you don’t add them twice.

In the Packs tab you can expand any applied pack to see its individual collectors (the scheduled data points) and views (the detail tabs). From here you can also turn individual data points on or off for just this class — see Enabling & Disabling Data Points.

Tip

Packs are installed and managed on the Monitoring Packs page first, then applied to classes here. If the pack you want isn’t in the list, install it first.

Class-level credentials and settings

The Settings tab on a class holds the shared configuration for every device in it. Anything you leave blank falls through to the parent class (and ultimately the defaults).

The settings are grouped:

Group	Settings	Notes
SNMP	Version (1, 2c, 3), community string, SNMPv3 user, auth protocol/key, privacy protocol/key	Used to poll metrics over SNMP.
SSH	Username, password, enable password	Used by SSH-based collectors.
Monitoring	Reachability method (ICMP, TCP, HTTP/HTTPS, SSH, Telnet), port, endpoint path, timeout, fallback method	Controls the Up/Down check.
Polling	SNMP poll interval, SSH poll interval (seconds)	How often data is gathered. Minimum 30 seconds.

After making changes, click Save Settings. The new values apply to every device in the class that doesn’t override them individually.

Note

Storing credentials on a class is the easiest way to keep devices in sync — set the community string once for Switch and every switch uses it. Override on an individual device only when that one device is different (see Overriding Device Details).

The other tabs

When a class is selected you also get:

• Devices — a list of every device currently in this class, with quick links to open each one. See Devices & Inventory to manage membership.
• Interfaces — patterns for interfaces to ignore on devices of this class, so noisy or irrelevant ports don’t clutter your view. See Working with Interfaces.

Where to go next

• Monitoring Packs — what packs contain and how to install them.
• Enabling & Disabling Data Points — fine-tune exactly what each class or device collects.
• Devices & Inventory — assign devices to classes and inspect them individually.