OID groups

An OID group defines a set of one or more OIDs of MIB objects retrieved by the SNMP monitor during a service test.

When creating an SNMP profile element, you specify an OID group containing the MIB objects that you wish to monitor. For example, if you wish to use the SNMP monitor to poll general performance data, you might define an OID group containing OIDs from the srSystem group of MIB objects, such as srSystemCPUUsageAverage, srSystemFreeMem, and srSystemSwapPercentUsed. You would then select this OID group in each profile element you create for monitoring system performance.

OID groups contain the following details for each MIB object:

• Name - The name of the MIB object, for example sysObjectID. This name is used in service level classifications and in $oidNamen monitor elements.
• OID Value - The numerical identifier of the MIB object instance expressed using either ASN.1 notation, for example .1.3.6.1.2.1.1.2.0, or the object’s name, for example sysObjectID.0.
  Note: When using ASN.1 notation, you must include the leading . character in the OID.
  Note: You may only use an object’s instance name to specify the OID value if the MIB document that defines the name is accessible by the monitor. The default directory for MIB documents is $ISMHOME/mibs.
• Unit - The units of the MIB object data, for example seconds, bytes, or bits per second (BPS).
  Bits per second values are calculated as:

  current_poll_value - prev_poll_value) / poll_interval * 8

• Selector
  The index value of the MIB object. Table 1 shows an example which results in the selector searching all the ifDescr rows for the value FastEthernet0/1, giving a row index of 2. Then the row ifPhysAddress.2 is queried and the value 0:6:53:34:d2:a1 is returned. In this way the index 2 is not directly specified, so if the index for FastEthernet0/1 changes, the OID groups do not need to be re-configured.

  Table 1. Use of the selector

  MIB object	MIB object value
  OID value	ifPhysAddress
  OID name	FastEthernet0/1PhysicalAddress
  OID unit	string
  Selector	ifDescr=FastEthernet0/1

To obtain specific information about the MIB objects provided by an SNMP-enabled device, see the device’s MIB document.