Network Working Group A. Bierman Request for Comments: 3433 Cisco Systems, Inc. Category: Standards Track D. Romascanu Avaya Inc. K.C. Norseth L-3 Communications December 2002
Entity Sensor Management Information Base
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes managed objects for extending the Entity MIB (RFC 2737) to provide generalized access to information related to physical sensors, which are often found in networking equipment (such as chassis temperature, fan RPM, power supply voltage).
For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580].
There is a need for a standardized way of obtaining information related to the physical sensors which are commonly found in networking equipment. Information such as the current value of the sensor, the current operational status, and the data units precision associated with the sensor, should be represented in a consistent manner for any type of sensor.
Physical sensors are represented in the Entity MIB with entPhysicalEntry and an entPhysicalClass value of 'sensor(8)'. The information provided in the ENTITY-SENSOR-MIB module (defined in this document) defines a sparse augmentation of the entPhysicalTable, for entries which represent physical sensors.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119. [RFC2119]
The MIB objects defined in this document provide a sparse augmentation to the entPhysicalTable in the Entity MIB, for entries in which the associated entPhysicalClass object is equal to 'sensor(8)'. An agent is expected to maintain an entPhySensorEntry with the same entPhysicalIndex value for each entPhysicalEntry representing a physical sensor. Therefore, implementation of the entityPhysicalGroup is required for agents that implement the Entity Sensor MIB.
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RFC 3433 Entity Sensor MIB December 2002
2.3. Relationship to General Thresholding Mechanisms
There are no specialized sensor value thresholding mechanisms defined in this MIB module. Instead, it is recommended that a generalized thresholding MIB, such as the mechanisms defined by the Alarm and Events groups of the Remote Network Monitoring MIB [RFC2819], be used for this purpose.
The Entity Sensor MIB contains a single group called the entitySensorValueGroup, which allows objects to convey the current value and status of a physical sensor.
The entitySensorValueGroup contains a single table, called the entPhySensorTable, which provides a small number of read-only objects:
entPhySensorType This object identifies the type of data units associated with the sensor value.
entPhySensorScale This object identifies the (power of 10) scaling factor associated with the sensor value.
entPhySensorPrecision This object identifies the number of decimal places of precision associated with the sensor value.
entPhySensorValue This object identifies the current value of the sensor.
entPhySensorOperStatus This object identifies the current operational status of the sensor (as it's known to the agent).
entPhySensorUnitsDisplay This object provides a textual description of the data units represented by the entPhySensorType and entPhySensorScale objects.
entPhySensorValueTimeStamp The object identifies the value of sysUpTime at the time the agent last updated the information in the entry. This object is only relevant if the agent uses a polling implementation strategy, (i.e., the associated entPhySensorValueUpdateRate object is greater than zero).
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RFC 3433 Entity Sensor MIB December 2002
entPhySensorValueUpdateRate This object indicates the nature of the agent implementation of the entPhySensorEntry, and contains the (possibly estimated) number of milliseconds that elapse between polling updates of the information in the associated entry. The value zero indicates that the agent always return current data for the entry (as opposed to the data as it was at the last polling interval).
IMPORTS MODULE-IDENTITY, OBJECT-TYPE, Integer32, Unsigned32, mib-2 FROM SNMPv2-SMI MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF TEXTUAL-CONVENTION, TimeStamp FROM SNMPv2-TC entPhysicalIndex, entityPhysicalGroup FROM ENTITY-MIB SnmpAdminString FROM SNMP-FRAMEWORK-MIB;
entitySensorMIB MODULE-IDENTITY LAST-UPDATED "200212160000Z" ORGANIZATION "IETF Entity MIB Working Group" CONTACT-INFO " Andy Bierman Cisco Systems, Inc. Tel: +1 408-527-3711 E-mail: abierman@cisco.com Postal: 170 West Tasman Drive San Jose, CA USA 95134
Dan Romascanu Avaya Inc. Tel: +972-3-645-8414 Email: dromasca@avaya.com Postal: Atidim technology Park, Bldg. #3 Tel Aviv, Israel, 61131
EntitySensorDataType ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An object using this data type represents the Entity Sensor measurement data type associated with a physical sensor value. The actual data units are determined by examining an object of this type together with the associated EntitySensorDataScale object.
An object of this type SHOULD be defined together with objects of type EntitySensorDataScale and EntitySensorPrecision. Together, associated objects of these three types are used to identify the semantics of an object of type EntitySensorValue.
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RFC 3433 Entity Sensor MIB December 2002
Valid values are:
other(1): a measure other than those listed below unknown(2): unknown measurement, or arbitrary, relative numbers voltsAC(3): electric potential voltsDC(4): electric potential amperes(5): electric current watts(6): power hertz(7): frequency celsius(8): temperature percentRH(9): percent relative humidity rpm(10): shaft revolutions per minute cmm(11),: cubic meters per minute (airflow) truthvalue(12): value takes { true(1), false(2) }
EntitySensorDataScale ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An object using this data type represents a data scaling factor, represented with an International System of Units (SI) prefix. The actual data units are determined by examining an object of this type together with the associated EntitySensorDataType object.
An object of this type SHOULD be defined together with objects of type EntitySensorDataType and EntitySensorPrecision. Together, associated objects of these three types are used to identify the semantics of an object of type EntitySensorValue." REFERENCE "The International System of Units (SI),
EntitySensorPrecision ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An object using this data type represents a sensor precision range.
An object of this type SHOULD be defined together with objects of type EntitySensorDataType and EntitySensorDataScale. Together, associated objects of these three types are used to identify the semantics of an object of type EntitySensorValue.
If an object of this type contains a value in the range 1 to 9, it represents the number of decimal places in the fractional part of an associated EntitySensorValue fixed- point number.
If an object of this type contains a value in the range -8 to -1, it represents the number of accurate digits in the associated EntitySensorValue fixed-point number.
The value zero indicates the associated EntitySensorValue object is not a fixed-point number.
Agent implementors must choose a value for the associated EntitySensorPrecision object so that the precision and
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RFC 3433 Entity Sensor MIB December 2002
accuracy of the associated EntitySensorValue object is correctly indicated.
For example, a physical entity representing a temperature sensor that can measure 0 degrees to 100 degrees C in 0.1 degree increments, +/- 0.05 degrees, would have an EntitySensorPrecision value of '1', an EntitySensorDataScale value of 'units(9)', and an EntitySensorValue ranging from '0' to '1000'. The EntitySensorValue would be interpreted as 'degrees C * 10'." SYNTAX Integer32 (-8..9)
EntitySensorValue ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An object using this data type represents an Entity Sensor value. An object of this type SHOULD be defined together with objects of type EntitySensorDataType, EntitySensorDataScale and EntitySensorPrecision. Together, associated objects of those three types are used to identify the semantics of an object of this data type.
The semantics of an object using this data type are determined by the value of the associated EntitySensorDataType object.
If the associated EntitySensorDataType object is equal to 'voltsAC(3)', 'voltsDC(4)', 'amperes(5)', 'watts(6), 'hertz(7)', 'celsius(8)', or 'cmm(11)', then an object of this type MUST contain a fixed point number ranging from -999,999,999 to +999,999,999. The value -1000000000 indicates an underflow error. The value +1000000000 indicates an overflow error. The EntitySensorPrecision indicates how many fractional digits are represented in the associated EntitySensorValue object.
If the associated EntitySensorDataType object is equal to 'percentRH(9)', then an object of this type MUST contain a number ranging from 0 to 100.
If the associated EntitySensorDataType object is equal to 'rpm(10)', then an object of this type MUST contain a number ranging from -999,999,999 to +999,999,999.
If the associated EntitySensorDataType object is equal to 'truthvalue(12)', then an object of this type MUST contain either the value 'true(1)' or the value 'false(2)'.
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RFC 3433 Entity Sensor MIB December 2002
If the associated EntitySensorDataType object is equal to 'other(1)' or unknown(2)', then an object of this type MUST contain a number ranging from -1000000000 to 1000000000." SYNTAX Integer32 (-1000000000..1000000000)
EntitySensorStatus ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An object using this data type represents the operational status of a physical sensor.
The value 'ok(1)' indicates that the agent can obtain the sensor value.
The value 'unavailable(2)' indicates that the agent presently cannot obtain the sensor value.
The value 'nonoperational(3)' indicates that the agent believes the sensor is broken. The sensor could have a hard failure (disconnected wire), or a soft failure such as out- of-range, jittery, or wildly fluctuating readings." SYNTAX INTEGER { ok(1), unavailable(2), nonoperational(3) }
-- -- Entity Sensor Table --
entPhySensorTable OBJECT-TYPE SYNTAX SEQUENCE OF EntPhySensorEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "This table contains one row per physical sensor represented by an associated row in the entPhysicalTable." ::= { entitySensorObjects 1 }
entPhySensorEntry OBJECT-TYPE SYNTAX EntPhySensorEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information about a particular physical sensor.
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RFC 3433 Entity Sensor MIB December 2002
An entry in this table describes the present reading of a sensor, the measurement units and scale, and sensor operational status.
Entries are created in this table by the agent. An entry for each physical sensor SHOULD be created at the same time as the associated entPhysicalEntry. An entry SHOULD be destroyed if the associated entPhysicalEntry is destroyed." INDEX { entPhysicalIndex } -- SPARSE-AUGMENTS ::= { entPhySensorTable 1 }
entPhySensorType OBJECT-TYPE SYNTAX EntitySensorDataType MAX-ACCESS read-only STATUS current DESCRIPTION "The type of data returned by the associated entPhySensorValue object.
This object SHOULD be set by the agent during entry creation, and the value SHOULD NOT change during operation." ::= { entPhySensorEntry 1 }
entPhySensorScale OBJECT-TYPE SYNTAX EntitySensorDataScale MAX-ACCESS read-only STATUS current DESCRIPTION "The exponent to apply to values returned by the associated entPhySensorValue object.
This object SHOULD be set by the agent during entry creation, and the value SHOULD NOT change during operation." ::= { entPhySensorEntry 2 }
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RFC 3433 Entity Sensor MIB December 2002
entPhySensorPrecision OBJECT-TYPE SYNTAX EntitySensorPrecision MAX-ACCESS read-only STATUS current DESCRIPTION "The number of decimal places of precision in fixed-point sensor values returned by the associated entPhySensorValue object.
This object SHOULD be set to '0' when the associated entPhySensorType value is not a fixed-point type: e.g., 'percentRH(9)', 'rpm(10)', 'cmm(11)', or 'truthvalue(12)'.
This object SHOULD be set by the agent during entry creation, and the value SHOULD NOT change during operation." ::= { entPhySensorEntry 3 }
entPhySensorValue OBJECT-TYPE SYNTAX EntitySensorValue MAX-ACCESS read-only STATUS current DESCRIPTION "The most recent measurement obtained by the agent for this sensor.
To correctly interpret the value of this object, the associated entPhySensorType, entPhySensorScale, and entPhySensorPrecision objects must also be examined." ::= { entPhySensorEntry 4 }
entPhySensorOperStatus OBJECT-TYPE SYNTAX EntitySensorStatus MAX-ACCESS read-only STATUS current DESCRIPTION "The operational status of the sensor." ::= { entPhySensorEntry 5 }
entPhySensorUnitsDisplay OBJECT-TYPE SYNTAX SnmpAdminString MAX-ACCESS read-only STATUS current DESCRIPTION "A textual description of the data units that should be used in the display of entPhySensorValue." ::= { entPhySensorEntry 6 }
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RFC 3433 Entity Sensor MIB December 2002
entPhySensorValueTimeStamp OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime at the time the status and/or value of this sensor was last obtained by the agent." ::= { entPhySensorEntry 7 }
entPhySensorValueUpdateRate OBJECT-TYPE SYNTAX Unsigned32 UNITS "milliseconds" MAX-ACCESS read-only STATUS current DESCRIPTION "An indication of the frequency that the agent updates the associated entPhySensorValue object, representing in milliseconds.
The value zero indicates:
- the sensor value is updated on demand (e.g., when polled by the agent for a get-request), - the sensor value is updated when the sensor value changes (event-driven), - the agent does not know the update rate.
entitySensorCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "Describes the requirements for conformance to the Entity Sensor MIB module." MODULE -- this module MANDATORY-GROUPS { entitySensorValueGroup }
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2578] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M., and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
[RFC2737] McCloghrie, K. and A. Bierman, "Entity MIB (Version 2)", RFC 2737, December 1999.
[RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", STD 62, RFC 3414, December 2002.
[RFC3415] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3415, December 2002.
[RFC2819] Waldbusser, S., "Remote network Monitoring Management Information Base", RFC 2819, May 2000.
[RFC3410] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction and Applicability Statements for Internet- Standard Management Framework", RFC 3410, December 2002.
There is one managed object in this MIB that may contain sensitive information. This is:
entPhySensorValue
This object may expose the values of particular physical sensors for a device.
SNMPv1 by itself is not a secure environment. Even if the network itself is secure (for example by using IPSec), there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB.
It is recommended that the implementors consider the security features as provided by the SNMPv3 framework. Specifically, the use of the User-based Security Model STD 62, RFC 3414 [RFC3414] and the View-based Access Control Model STD 62, RFC 3415 [RFC3415] is recommended.
It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB, is properly configured to give access to only the objects, and those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.
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