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The SNMP Polling Monitor is designed to poll the SNMP agent and retrieve the values of a given OID (object identifier), or the values of an SNMP table, thereby enabling you to easily identify the source of the problem or just be informed of the status of the monitored device/attribute.
 SNMP polling supports SNMP v1, v2c, and v3.
To poll an SNMP agent
| 1. | In the PATROL Console, right-click the Host or Monitor Group icon and select KM Commands > New > Monitor... |
| 2. | Select SNMP Polling from the drop-down list and click Next. |
 If SNMP is deactivated on the PATROL Agent, a warning message is displayed, inviting you to activate it using the following configuration variable: /snmp/support. Besides, Monitoring Studio will trigger an alert on the CollectionErrorCount parameter under the Monitoring Studio icon if SNMP is disabled in the configuration and one or several SNMP Monitors have been created.
Polling SNMP Agents - Value Selection
| 3. | Select the type of value you want to poll: |
| 4. | If you have selected A single value from one OID, the following dialog box is displayed: |
Polling SNMP Agents - SNMP Polling: Single Value
The SNMP version and Port number configured at the host level is displayed at the top of the dialog box.
| • | OID to poll: Enter the OID (object identifier) to poll, as indicated in the Management Information Base (MIB). |
| • | Report execution errors in Group's CollectionErrorCount: Select this option to have the CollectionErrorCount parameter of the Group reflect possible alerts triggered upon the SNMP monitoring execution. The CollectionErrorCount parameter of the Group reports on the collection errors of any Monitor, associated to the group, for which this option is available and selected, providing a global view of the collection errors for the whole Group. |
Monitoring Studio will try to poll the OID to identify its type. This will determine which parameters are activated ("Content" for strings, "Value" for numbers). If, for some reason, the OID cannot be polled, a warning message is displayed and invites you to select an OID type, either “string” or “number,” to let Monitoring Studio know what type of value is expected. If you are not sure about:
| • | the OID type, it is recommended to select “The OID content is a string.” |
| • | the exact OID to poll, you should use a SNMP MIB Browser tool to identify which OID corresponds to which variable. You can also use the Monitoring Studio built-in SNMP Browser tool to list the available OID variables and their values. To do so, right-click the main Monitoring Studio icon > KM Commands > Tools > SNMP Browser. |
Polling SNMP Agents - Monitored Value
| • | If the OID returns a number, select the parameters you wish to collect: |
| ▪ | Delta: Calculates the difference between values collected during two consecutive polling. |
| ▪ | Delta per second/minute/hour: Reports the value resulting of the division of the Delta by the number of seconds/minutes/hours elapsed between the collection intervals. |
| ▪ | Raw Value: Reports the actual value collected upon data polling. |
| • | Discard negative Delta values: Select this option if you want to exclude negative Delta values from other collected values. |
Discarding negative Delta values can be particularly relevant when the raw value consists in a counter that keeps increasing: if the raw value decreases, it indicates that the counter has been reset and that the value should be discarded.
| • | Rescaling: Use this option to configure Monitoring Studio to rescale the value that is being extracted in order to have a more readable graph in the PATROL Console. The available rescaling options are: |
| ▪ | Divide the value by a value that gives you the reading in terms best suited to you |
| ▪ | Multiply the extracted value by a constant factor |
| This can be useful if you extract numeric values in bytes but prefer to see the graph in megabytes. In such a case, you would divide the values by 1048576 (1024*1024). |
| 5. | If you have selected Multiple values from rows of an SNMP table, the following dialog box is displayed: |
Polling SNMP Agents - SNMP Polling: Multiple Values
The SNMP version and Port number configured at the host level is displayed at the top of the dialog box.
| • | SNMP Table OID: Enter the Table OID (object identifier) to poll, as indicated in the Management Information Base (MIB). This OID should always end with ".1". |
| • | Columns to retrieve, separated by commas: Enter the column numbers from which values should be retrieved. Enter “ID” to retrieve the row identifier. Leave the field blank to retrieve values from the entire row. Enter "ID" to retrieve the row identifier |
If for some reason, the OID cannot be polled, a message is displayed stating that the table seems to be empty. In such a case, verify that you have entered the right OID and/or that the table really exists and contains values.
| 7. | Click Finish. The corresponding SNMP Polling instance (SNMP Polling: <Display Name>) is created in the PATROL Console. The collected parameters for SNMP Polling Monitors are listed in the SEN_MS_SNMPPOLLING chapter. |
Monitoring Studio will get the value and allow you to store it in a graph, or search for strings in the OID content.
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