SNMP Polling

The aim of this tool is to poll the SNMP agent and retrieve the values of a given OID (object identifier), or the values of an SNMP table, thereby enabling the operator to easily identify the source of the problem or just be informed of the status of the monitored device/parameter.

Many applications rely on middleware instrumented with SNMP (Simple Network Management Protocol) agents, which contain managed objects that provide information related to the current state of its operation. These objects are arranged in a Management Information Base (MIB). SNMP is an Application Layer protocol that allows external tools to communicate with the agent and read the values of the objects.

The SNMP agent collects critical information about the middleware, and Monitoring Studio, directly polls the agent and retrieves the value of a given OID (object identifier). All the operator has to do is interrogate the MIB and interpret the value of the OID retrieved by Monitoring Studio. The 3 basic steps to poll the SNMP agent are:

Monitoring Studio will get the value and allow you to store it in a graph, or search for strings in the OID content…

To create a new SNMP polling: Right-click the Application/Container icon in the PATROL Console and select KM Commands > New > SNMP polling.

To edit an existing SNMP polling: Right-click the SNMP polling icon in the PATROL Console and select KM Commands > Edit.

Step 1: Select the type of value you want to poll: Single OID value or SNMP table values

•	A single value from one OID: Select this option to poll a value from one OID

•	Multiple values from rows of an SNMP table: Select this option to poll several values from an SNMP table

•	Host: Enter the IP of the computer running the SNMP agent that will be polled. If it is the same server as the one the PATROL agent runs on, it is possible to use the following IP: 127.0.0.1

•	OID to poll: Enter the OID (object identifier) to poll, as given by the Management Information Base (MIB)

After clicking Next, the wizard will try to poll the OID to identify its type. If, for some reason, the OID cannot be polled, a warning message is displayed. The user must select an OID type, either “String” or “Integer,” to let Monitoring Studio know what kind of value is expected. If you are not sure about the OID type, it is recommended to select “The OID returns a string.”

If you are unsure about 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. Right-click the main Monitoring Studio icon > KM Commands > Tools > SNMP Browser.

▪	Delta: Calculates the difference between values collected during two consecutive polling.

▪	DeltaPerSecond: Reports the value resulting of the division of the Delta by the number of seconds elapsed between the collection times

•	Select the option "Discard negative Delta values" if you do not want negative values to be reported on the graph.

•	Use the Rescaling 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 then gives you the reading in terms best suited to you

This can be useful if you extract numeric values in bytes but prefer to show a graph in megabytes. In such a case, you would divide the values by 1048576 (1024*1024).

Step 2: Identifying the SNMP agent and the list of columns from the SNMP table to poll

•	Host: Enter the IP of the computer running the SNMP agent that will be polled. If it is the same server as the one the PATROL agent runs on, it is possible to use the following IP: 127.0.0.1

•	SNMP Table OID: Enter the Table OID (object identifier) to poll, as given by the Management Information Base (MIB)

•	List of table columns to poll: Enter the column numbers whose values should be retrieved. Enter “ID” to retrieve the row identifier. Leave the field blank to retrieve all values; or enter the column numbers separated by commas. Example: 4,8,9.

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 has values.

•	Object display name: Label displayed in the PATROL Console for this SNMP polling object

•	Object internal identifier (ID): PATROL internal identifier of this SNMP polling monitoring

What thresholds do you want to set for the newly created object? The drop-down list allows you to select the mode of setting alert thresholds:

•	Use default thresholds: Uses the default thresholds set by Monitoring Studio

•	Set custom thresholds: Allows you to customize the thresholds for all parameters of the instance

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Use default thresholds and customize them: Sets the default Monitoring Studio thresholds on certain parameters (see list of parameters with default thresholds) and then allows you to customize any/all of them. This is mainly intended to help save time if you wish to customize the thresholds of just one of many parameters for the instance, and leave the default settings for the others.

If you select Use default thresholds and customize them; on clicking Finish, the Set Thresholds panel will appear, and certain parameters for the instance will appear with an asterisk symbol - indicating that they already have thresholds. You can then customize (any/all) the thresholds of the parameters as per your specific needs.

•	Do not set any thresholds: No thresholds will be set on any parameter of the instance, and as a result no alerts will be triggered. Monitoring Studio will poll the object and return the output of the polling, but will not raise any alerts until you set thresholds.

Thresholds can be set or modified at anytime by right-clicking on the instance > KM commands > Set Thresholds.

For details on the parameters discovered, please refer to the Reference Guide. SNMP Polling objects are instances of the SW_SNMP_POLLING class.