Power Ethernet MIB
Extracted elements (20)
The IEEE 802.3af working group deliberately limited its scope to defining only the hardware registers needed to build management interfaces, without specifying a full SNMP MIB. This RFC fills that gap by extending the Ethernet-like Interfaces MIB (RFC 3635) with the management objects required for PSE operation.
The MIB uses a Group/Port two-level index scheme (pethPsePortGroupIndex, pethPsePortIndex) to support modular numbering, allowing implementors to represent field-replaceable units as groups of ports. This mirrors the IEEE 802.3 management standard's recommended entity hierarchy.
This MIB module is an extension of the Ethernet-like Interfaces MIB defined in RFC 3635. It is compliant with SMIv2 (STD 58: RFC 2578, RFC 2579, RFC 2580) and references IEEE 802.3af hardware register definitions for all normative PSE behavior.
Deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Implementers are RECOMMENDED to deploy SNMPv3 with full cryptographic mechanisms (authentication and privacy) and to restrict GET/SET access to only those principals with legitimate rights.
For non-modular devices, the group index value 1 MUST be used in pethPsePortGroupIndex, pethMainPseGroupIndex, and pethNotificationControlGroupIndex. The same value MUST be used across all three index objects to refer to a given box in a stack or module in a rack.
The pethMainPowerUsageOnNotification and pethMainPowerUsageOffNotification MUST each observe a minimum inter-notification gap of at least 500 milliseconds per object instance to prevent notification storms when power consumption oscillates around the threshold.
The pethMainPseGroup and pethMainPowerNotificationGroup object groups are mandatory for PSE systems that implement a main power supply; the pethPsePortGroup, pethPsePortNotificationGroup, and pethNotificationControlGroup are mandatory for all conforming implementations.
The pethPsePortOnOffNotification SHOULD be sent on every PSE port detection status change except transitions into the searching state. At least 500 milliseconds must elapse between successive notifications from the same object instance.
Five per-port Counter32 fault counters track distinct PSE state-machine error transitions: pethPsePortMPSAbsentCounter (POWER_ON → IDLE via tmpdo_timer_done), pethPsePortInvalidSignatureCounter (SIGNATURE_INVALID), pethPsePortPowerDeniedCounter (POWER_DENIED), pethPsePortOverLoadCounter (ERROR_DELAY_OVER), and pethPsePortShortCounter (ERROR_DELAY_SHORT).
pethPsePortAdminEnable (TruthValue, read-write) enables or disables PSE function on a port. When false(2), the interface behaves as if it has no PSE capability. References IEEE 802.3af Section 30.9.1.1.2 aPSEAdminState.
pethPsePortPowerClassifications reports the IEEE 802.3af power class of the attached Powered Device: class0(1) through class4(5). This object is only valid while pethPsePortDetectionStatus reports deliveringPower.
pethPsePortPowerPairs indicates which Ethernet pin pairs are used for power delivery: signal(1) for data pairs or spare(2) for spare pairs. The object is writable only when pethPsePortPowerPairsControlAbility is true.
pethPsePortPowerPriority exposes three priority levels — critical(1), high(2), low(3) — that a power management algorithm may use to determine which ports to disconnect first when an over-current condition occurs. Critical ports (e.g., E911 phones) should be assigned higher priority.
The pethMainPseTable defines objects for managing the main power supply of a PSE device, including nominal power (pethMainPsePower, Gauge32 in Watts), operational status (on/off/faulty), measured consumption (pethMainPseConsumptionPower), and a usage threshold (pethMainPseUsageThreshold, 1–99%). All read-write values are persistent across restart/reboot.
The pethNotificationControlTable provides per-group control over whether SNMP notifications are sent from the agent. The single writable object pethNotificationControlEnable (TruthValue) enables or disables notifications for each group. All read-write values are persistent across restart/reboot.
The pethPsePortTable defines objects for configuring and monitoring power characteristics of each PSE port, indexed by pethPsePortGroupIndex and pethPsePortIndex. It includes port admin enable, power pairs, detection status, power priority, and fault counters. All read-write object values are persistent across restart/reboot.
This document registers the POWER-ETHERNET-MIB module under the MIB-2 subtree at OID { mib-2 105 }, making powerEthernetMIB the root of all objects defined in this specification.
Setting pethMainPseUsageThreshold or pethNotificationControlEnable to incorrect values can produce an excessive number of SNMP traps sent to management stations. Even readable objects such as pethPsePortPowerPriority and pethPsePortPowerClassifications may be sensitive and should have controlled GET and NOTIFY access, with values optionally encrypted.
Setting pethPsePortAdminEnable, pethPsePortPowerPairs, pethPsePortPowerPriority, or pethPsePortType to incorrect values can result in improper PSE operation, including failure of a Powered Device to receive power. Unauthorized SET operations in a non-secure environment pose a direct risk to network-powered equipment.
pethPsePortDetectionStatus maps the IEEE 802.3af PSE state machine to six MIB enumeration values: disabled(1) = DISABLED state; searching(2) = all other transient states; deliveringPower(3) = POWER_ON for duration > tlim_max; fault(4) = TEST_ERROR; test(5) = TEST_MODE; otherFault(6) = IDLE due to error_conditions.