This documentation supports the 11.1 version of BMC Discovery.

To view an earlier version of the product, select the version from the Product version menu.

Recognizing SNMP devices

Unknown SNMP devices are devices that can be accessed via SNMP, but that BMC Discovery has insufficient knowledge of to discover fully. Such devices might be switches, printers, and so on that are not defined in TKU.

The SNMP Recognition Rules page enables you to create rules for unknown SNMP devices so that they are identified in the future by BMC Discovery. From these rules, BMC Discovery can create SNMPManagedDevice, Printer, and Network Device nodes. The node type and capabilities are used to choose the correct class (BMC_ComputerSystem, BMC_Printer, and so on) to model in the CMDB.

For BMC Discovery to recognize a device, appropriate SNMP credentials must be available, enabled, and valid for the IP address.

Recognition approaches

An approach is a way of recognizing a device. BMC Discovery uses real-world knowledge when offering possible recognition approaches. For example, if the sysObjectID states that the manufacturer is Xerox, then the device is almost certainly a printer. Similarly, Dell and HP printers always have printer in the sysDescr. The same practice is used for switches and load balancers. Where the device would be modeled as a Network Device node, you can always choose to create an SNMP Managed Device node instead.

In the sysDescr, you might be able to see information about the device. From there, the most appropriate recognition approach might be obvious; for example, where the sysDescr begins "Dell 1350cnw Color Printer" and the approaches offered are:

  • SNMP Managed Device (dell/generic)
  • Printer (dell/printer)
  • Network Device (dell/generic)
  • Network Device (dell/powerconnect3000)

The approach most likely to be successful is "Printer (dell/printer)," although it is possible to use any listed.

Limitations of recognized devices

Where SNMP devices are recognized using these recognition rules, they are not fully discovered as they would be with a TKU pattern. Rather, they provide a means of recognizing known device types.

The approach determined is the most likely to succeed but is not always correct. If the data has not been collected correctly, then you need to use the alternative generic approach provided; for example, (dell/generic) in the preceding example. If that also fails, the device cannot be discovered without adding support for it to a TKU. In this case, use the device capture to download the zipped MIB, and send it to the BMC Software Technology Update (TKU) team to request that support be included in BMC Discovery for that SNMP device.

The recognition approach does not work for some devices because they do not support the generic parts of the MIB that BMC Discovery queries. Where no device is created, the methods required to create one might have failed because the queries cannot be run against the unsupported generic parts of the MIB.

To view unrecognized SNMP devices

From the main menu, select Model > Devices.
The Model >Devices page opens.

Shows unrecognized SNMP devices on the SNMP Recognition Rules page.

The SNMP Managed Devices page shows the following information for each unrecognized SNMP device.

Field name



The number of this type of unrecognized device that have been detected.

InferredThe number of SNMP devices that have been created using this rule.


The SNMP System Object ID of the SNMP managed device.

Sample sysDescr

An excerpt from the SNMP system description.


  • Unknown Device—An unrecognized SNMP device that has no recognition rule created.
  • Pending Discovery—A device for which a TKU has a rule, but has not been scanned since the TKU was loaded.
  • Rule Defined—A rule is defined for that sysObjectID
  • Overridden by TKU—A rule is defined for the sysObjectID but the loaded TKU also has one defined. The TKU rule takes precedence.
  • Generic sysObjectID—Where multiple devices share the same sysObjectIDs, for example embedded devices using the NET-SNMP or UCD SNMP agent, they cannot be fully identified using this approach. Some of these devices can be identified by reference to other SNMP System Object IDs, though this is not user configurable.


Kind of device. For example, SNMP Managed Device, Printer, or Network Device.


The vendor of the SNMP managed device.


The model name of the SNMP managed device.


An dynamic list of available actions. The following are displayed depending on the Status as previously described:

  • Create—Open the SNMP Recognition Rule dialog and create recognition rules. Displayed where status is Unknown Device.
  • When you have created a rule, the following actions are available:
    • Edit—Open the SNMP Recognition Rule dialog to edit existing recognition rules. This action is removed when a TKU rule overrides a recognition rule.
    • Delete—Delete an existing recognition rule.
    • Scan—Scan the device using the recognition rule to identify it.

To create recognition rules for a device

  1. For the unrecognized device for which you want to create a rule, select Create from the Actions column.
    The SNMP Recognition Rule dialog is displayed.
    Shows the dialog into which you enter data to create recognition rules.

  2. Enter information about the device into the fields on the SNMP Recognition Rule dialog.

    Field name



    A read-only field showing the sysObjectID; also provides a link to a new Google search page for the sysObjectID.


    A read-only field showing the sysDescr.


    A drop-down list showing available recognition approaches. Select the one most appropriate for the device. For more information, see approach.


    Enter the vendor of the device. This information can often be obtained from the sysDescr field. You cannot save the recognition rule without entering a Vendor name.


    Enter the model name or number of the device. This information can often be obtained from the sysDescr field. You cannot save the recognition rule without entering a Model name.


    Select the device capabilities from the drop-down list. For example, for the "Dell 1350cnw Color Printer", select Print. Where a device has multiple capabilities, click Add another and select from the new drop-down list. For example, a self-contained NAS might also have a Media Library, so you should select both of those capabilities.


    Select an IP address from the drop-down list. This list is populated with the IP addresses that the unrecognized device has been reported on. Click Start to start the test.
    As the test progresses, the methods run are shown along with results and a success or failure icon.

  3. Click Save to save the recognition rule.
    The SNMP Recognition Rules page is displayed, and the status of the rule is now Rule Defined.

Importing or exporting recognition rules

You can import or export recognition rules so you can transfer them between BMC Discovery instances.

To import recognition rules

  1. From the SNMP Recognition Rules page, select Import Recognition Rules from the Actions menu.
    The UI displays the Import SNMP Recognition Rules dialog.
  2. Click Browse and locate the zipped recognition rules file on your file system.
  3. Select the zipped recognition rules file and click Import.
    The SNMP recognition rules file is imported.


    If an SNMP Recognition Rule is exported and subsequently imported to the same BMC Discovery machine, any changes made to the rule in the UI between the export and import are overwritten without warning.

To export recognition rules

  1. From the SNMP Recognition Rules page, select the recognition rules that you want to export.
  2. Select Export Recognition Rules from the Actions menu.
    The rule is exported, and the UI displays a banner showing the number of rules exported and a download link.
  3. Click the download link and save the zipped recognition rules file.

To scan with a recognition rule

After you have created a recognition rule, you can scan the IP address.

  1. Click Scan from the Actions column.
    The Add a New Run dialog is displayed populated with the IP address to scan.
  2. Click OK to scan the device.
    The Discovery page is displayed showing the Currently Processing Runs tab. When the run is completed, it is moved to the Recent Runs tab.
  3. Click Recent Runs.
  4. Click the entry on the Recent Runs tab to see the DiscoveryRun page for that run.
  5. Click the entry in the Summary section of the DiscoveryRun page to see the new SNMP Managed Device or Printer.

If you delete a recognition rule that you have used to scan a device, the device is no longer unrecognized and does not appear on the SNMP Recognition Rules page. To create a new rule for the device, you must rescan it. Because there is no recognition rule in place (it was deleted), the device is unrecognized again and appears on the SNMP Recognition Rules page.

Recognition rules and consolidation

When you have developed SNMP recognition rules on a scanning appliance in a consolidating environment, you must also copy the recognition rules to any other scanning appliance in the consolidating environment.

  1. From the SNMP Recognition Rules page, select the rules that you want to copy to the other scanning appliance.
  2. From the Actions menu, select Export Recognition Rules.
    An information banner displays the number of rules that have been exported and provides a Download link.
  3. Click the Download link and save the file onto your file system.

For every other scanning appliance:

  1. Log in to the scanning appliance and navigate to the SNMP Recognition Rules page.
  2. From the Actions menu, select Import Recognition Rules.
  3. Enter the file name of the exported rules file in the Filename dialog box (or click Browse... to locate the file).
  4. Click Import.
    The screen is refreshed and the imported rules shown against corresponding unrecognized devices.

You do not need to copy the rules to consolidation appliances.

Related topics

Capturing SNMP devices

Was this page helpful? Yes No Submitting... Thank you