SNMP Support

Standard SNMP support includes a generic interface for all SNMP data sources in which MIBs are present. Specific measures are accessed using a combination of object ID (OID) and instance ID (when objects have more than one instance). The challenge with this approach is that you must know exactly which counter instance is to be applied. Instances are only distinguished by instance ID, not by instance name. Compounding this challenge is the fact that when servers reboot, certain instance numbers can change due to dynamic monitoring-object creation. Therefore monitoring scripts must be able to cope with dynamic monitoring targets.

The value of Silk Performer's enhanced SNMP support is that it allows you to access values not by OID and instance ID, but by OID and instance name.

The following example illustrates the enhanced SNMP support that is available with Silk Performer. This example shows how predefined ESNMP measures are defined, how they are used, and how additional measures can be added to the list of pre-defined measures.

Identifying instance IDs and OIDs

The first step in working with a predefined ESNMP measure is to identify the OID, instance ID, and instance name of a WebLogic counter. The JDBC Connection Pool Runtime Active Connections Current Count for a certain instance is accessible with the OID: + <Instance ID>

Without enhanced SNMP support, you have to provide the OID of the table containing the values and the correct instance ID.

JDBC Connection Pool Runtime Object Name and JDBC Connection Pool Runtime Name contain the human readable names of the instances and are accessible with the OIDs: + <Instance ID> for “Object Names”

and... + <Instance ID> for “Names”

ESNMP support provides you with the option of specifying an instance name, retrieving an instance ID using the (object-) name table, and then getting the value for the correct counter. With ESNMP support, the following must be provided:

  • OID of the table containing the values
  • Instance name
  • OID of the table containing the instance names