Monitoring and Control MIB for Power and Energy
Extracted elements (28)
The eoMeterCapabilitiesTable was designed to allow NMS applications to discover which monitoring tables are available without a trial-and-error polling process. Because Energy Objects vary widely in instrumentation (some support only power metering, others add energy and power attributes), a capability advertisement object is necessary to avoid wasted SNMP queries.
The eoPowerMeasurementCaliber object distinguishes among unavailable, unknown, actual, estimated, and static measurement methods because NMS systems must account for differing reliability when aggregating power data across heterogeneous devices. Devices that cannot instrument power physically set caliber to unavailable and eoPower to 0, rather than reporting misleading values.
The sign convention for eoPower (positive = consuming, negative = producing) was chosen to handle Energy Objects such as solar panels, batteries discharging, or UPS units that supply power back to the network. A single signed integer eliminates the need for a separate direction flag.
Three energy interval collection modes (period, sliding, total) were adopted directly from IEC standard 61850-7-4, rather than defining a novel scheme. This alignment with an existing international standard ensures interoperability with building automation and industrial energy management systems that already use IEC 61850.
Energy Objects that lack an ENTITY-MIB instance (e.g., building gateway proxies for BACnet, home energy controllers) set eoPhysicalEntity to zero using the PhysicalIndexOrZero Textual Convention. The ENERGY-OBJECT-MIB is therefore applicable to devices where ENTITY-MIB and ENTITY-SENSOR-MIB cannot be assumed.
The ENTITY-SENSOR MIB (RFC 3433) uses a scientific-notation precision model (entPhySensorPrecision = number of decimal places) that does not align with ANSI C12.20 and IEC 62053 accuracy classes required for electricity metering. The ENERGY-OBJECT-MIB therefore introduces its own eoPowerAccuracy (in hundredths of a percent) and eoPowerUnitMultiplier (SI exponent) rather than reusing the ENTITY-SENSOR MIB objects.
The ENTITY-STATE MIB (RFC 4268) standby states can be mapped to Energy Object Power States: entStateStandby unknown/hotStandby/coldStandby map to Power State unknown/ready/standby respectively, and providingService can map to any low–high Power State. No formal mapping is mandated; this is informative guidance for implementations using both MIBs.
The Power-over-Ethernet MIB (RFC 3621) is indexed by pethMainPseGroupIndex rather than entPhysicalIndex, so there is no direct mapping. When RFC 3621 is supported, the Energy Object fields eoethPortIndex and eoethPortGrpIndex carry the pethPsePortIndex and pethPsePortGroupIndex values; otherwise they are set to zero using the PethPsePortIndexOrZero and PethPsePortGroupIndexOrZero Textual Conventions.
When the LLDP-MED MIB is supported, eoPowerMeasurementLocal can be mapped to lldpXMedLocXPoEPDPowerSource: fromPSE(2) maps to false and local(3) maps to true. The LLDP-MED power priority (lldpXMedRemXPoEPDPowerPriority) is derived from pethPsePortPowerPriority (RFC 3621), accessible via eoethPortIndex/eoethPortGrpIndex.
Every Energy Object MUST implement entPhysicalIndex, entPhysicalClass, entPhysicalName, and entPhysicalUUID from the ENTITY-MIB (RFC 6933). The Module Compliance of ENTITY-MIB v4 with respect to entity4CRCompliance MUST be supported.
Multiple eoEnergyParametersIntervalMode types MAY be configured simultaneously on the same Energy Object using distinct eoEnergyParametersIndex values, subject to device capability. This allows parallel periodic, sliding, and total collection from a single Energy Object.
The ENERGY-OBJECT-CONTEXT-MIB (RFC 7461) SHOULD be implemented as a prerequisite for this MIB module, since the eoPowerTable is a sparse extension of the eoTable in that module. The NMS must first poll the ENERGY-OBJECT-CONTEXT-MIB to discover all Energy Objects and their relationships.
The eoEnergyDiscontinuityTime SHALL indicate the sysUpTime (RFC 3418) when the device was last reset, to flag interruptions in continuous energy measurement totals. This enables NMS systems to detect and account for measurement gaps.
The eoPower value MUST be less than or equal to the maximum power that can be consumed at the Power State specified by eoPowerState. When eoPowerMeasurementCaliber is 'unavailable', the eoPower value must report 0.
The ENERGY-OBJECT-MIB module consists of five tables: eoMeterCapabilitiesTable (instrumentation available per Energy Object), eoPowerTable (power consumption and state), eoPowerStateTable (Power State statistics), eoEnergyParametersTable (energy collection configuration), and eoEnergyTable (energy/demand log). All tables are indexed by entPhysicalIndex.
The eoEnergyTable records per-interval energy data indexed by eoEnergyParametersIndex and eoEnergyCollectionStartTime. Fields include eoEnergyConsumed, eoEnergyProvided, eoEnergyStored (all in watt-hours scaled by eoEnergyUnitMultiplier), eoEnergyAccuracy, eoEnergyMaxConsumed, eoEnergyMaxProduced, and eoEnergyDiscontinuityTime. The buffer retains eoEnergyParametersIntervalNumber intervals, replacing the oldest except when the oldest holds the max values.
The eoMeterCapabilitiesTable uses a BITS object (eoMeterCapability) with bits for none(0), powermetering(1), energymetering(2), and powerattributes(3) to advertise which MIB groups an agent supports. This allows NMS applications to discover available tables without a trial-and-error walk.
The eoPowerMeasurementCaliber object classifies how eoPower was obtained: unavailable(1), unknown(2), actual(3) — hardware measurement, estimated(4) — algorithmic derivation from state/utilization, or static(5) — external tables or model specifications. Implementation of eoEnergyParametersTable only makes sense when caliber is actual(3).
The IANAPowerStateSet-MIB defines the PowerStateSet Textual Convention encoding three Power State Sets: IEEE1621 (base value 256, Off/Sleep/On), DMTF (base value 512, 15 states including graceful variants), and EMAN (base value 1024, 12 states from MechOff through High). The encoding formula is: Power State Set S occupies value S*256, and Power State X within set S occupies S*256 + X + 1.
The POWER-ATTRIBUTES-MIB module consists of three tables for AC power quality: eoACPwrAttributesTable (single-phase aggregate measurements including voltage, current, frequency, active/reactive/apparent power, power factor, and THD), eoACPwrAttributesDelPhaseTable (DEL three-phase per-phase voltage), and eoACPwrAttributesWyePhaseTable (WYE three-phase per-phase measurements). Aligned with IEC 61850 7-2.
Three eoEnergyParametersIntervalMode types define how energy intervals are collected: period(1) — non-overlapping sequential intervals (S_{n+1} = S_n + L); sliding(2) — overlapping windows where the inter-window offset is set by eoEnergyParametersIntervalWindow; total(3) — a single continuous measurement since last reset, where eoEnergyParametersIntervalNumber must be 1 and eoEnergyParametersIntervalLength is ignored. Multiple modes MAY be configured simultaneously per Energy Object.
The ENERGY-OBJECT-MIB module is assigned OID mib-2 229. The POWER-ATTRIBUTES-MIB module is defined under a separate OID (specified in Section 9.3). Both are registered with IANA as part of the mib-2 subtree.
The IANAPowerStateSet-MIB module is assigned OID mib-2 228 and is maintained by IANA. It defines the PowerStateSet Textual Convention and the registry of Power State Sets and individual Power States. New values are requested via email to [email protected]; the authoritative list is at http://www.iana.org/assignments/power-state-sets.
Several MIB objects are read-write and could be exploited to alter device power states or energy logging configuration: eoPowerAdminState (controls Power State), eoPowerStateEnterReason, and all eoEnergyParameters table objects. Implementations SHOULD use SNMPv3 with authentication and privacy (USM) and apply VACM access control to restrict write access to these objects to authorized management stations only.
An Energy Object transitions between Power States via the admin/oper state model: eoPowerAdminState holds the requested Power State (read-write), eoPowerOperState holds the current operational Power State (read-only). A difference between the two values indicates the object is busy transitioning. eoPowerStateEnterReason records the reason for the last admin transition. An eoPowerStateChange SNMP notification is generated when eoPowerStateIndex, eoPowerOperState, or eoPowerAdminState changes.
The eoPowerAccuracy object is an Integer32 in the range 0–10000, expressed in hundredths of a percent, representing the assumed accuracy of the eoPower measurement (e.g., 1010 means ±10.1%). A value of zero means accuracy is unknown or not applicable. This models ANSI C12.20 (0.2, 0.5%) and IEC 62053-22 (0.1, 0.2, 0.5, 1, 3%) accuracy classes.
The PowerStateSet TC encodes both the Power State Set identifier and individual Power State values in a single INTEGER. For a Power State Set S, the named number S*256 identifies the set; for Power State X within set S, the value is S*256 + X + 1. Power States within a set are limited to 255 distinct values (0–254).
The UnitMultiplier Textual Convention encodes SI unit scale factors as integers from yocto(-24) to yotta(24), following IEEE 61850 Annex A. All power and energy measurements in the MIB use the pattern BaseValue * 10^UnitMultiplier, with UnitMultiplier held in a companion object (e.g., eoPowerUnitMultiplier, eoEnergyUnitMultiplier).