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 (RFC2737) 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).

Table of Contents

1 The Internet-Standard Management Framework .................. 2
2 Overview .................................................... 2
2.1 Terms ................................................... 2
2.2 Relationship to the Entity MIB .......................... 2
2.3 Relationship to General Thresholding Mechanisms ......... 3
3 MIB Structure ............................................... 3
4 Definitions ................................................. 4
5 Intellectual Property ....................................... 13
6 Acknowledgements ............................................ 14
7 Normative References ........................................ 14
8 Informative References ...................................... 14
9 Security Considerations ..................................... 15
10 Authors' Addresses .......................................... 16
11 Full Copyright Statement .................................... 17

1. The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC3410 [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,
RFC2578 [RFC2578], STD 58, RFC2579 [RFC2579] and STD 58, RFC2580
[RFC2580].

2. Overview

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.

2.1. Terms

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, RFC2119.
[RFC2119]

2.2. Relationship to the Entity MIB

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.

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.

3. MIB Structure

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).

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).

4. Definitions

ENTITY-SENSOR-MIB DEFINITIONS ::= BEGIN

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

K.C. Norseth
L-3 Communications
Tel: +1 801-594-2809
Email: kenyon.c.norseth@L-3com.com
Postal: 640 N. 2200 West.

Salt Lake City, Utah 84116-0850

Send comments to <entmib@ietf.org>
Mailing list subscription info:
http://www.ietf.org/mailman/listinfo/entmib "
DESCRIPTION
"This module defines Entity MIB extensions for physical
sensors.

Copyright (C) The Internet Society (2002). This version
of this MIB module is part of RFC3433 see the RFC
itself for full legal notices."

REVISION "200212160000Z"
DESCRIPTION
"Initial version of the Entity Sensor MIB module, published
as RFC3433."
::= { mib-2 99 }

entitySensorObjects OBJECT IDENTIFIER
::= { entitySensorMIB 1 }

-- entitySensorNotifications OBJECT IDENTIFIER
-- ::= { entitySensorMIB 2 }
entitySensorConformance OBJECT IDENTIFIER
::= { entitySensorMIB 3 }

--
-- Textual Conventions
--

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.

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) }

"
SYNTAX INTEGER {
other(1),
unknown(2),
voltsAC(3),
voltsDC(4),
amperes(5),
watts(6),
hertz(7),
celsius(8),
percentRH(9),
rpm(10),
cmm(11),
truthvalue(12)
}

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),

National Institute of Standards and Technology,
Spec. Publ. 330, August 1991."
SYNTAX INTEGER {
yocto(1), -- 10^-24
zepto(2), -- 10^-21
atto(3), -- 10^-18
femto(4), -- 10^-15
pico(5), -- 10^-12
nano(6), -- 10^-9
micro(7), -- 10^-6
milli(8), -- 10^-3
units(9), -- 10^0
kilo(10), -- 10^3
mega(11), -- 10^6
giga(12), -- 10^9
tera(13), -- 10^12
exa(14), -- 10^15
peta(15), -- 10^18
zetta(16), -- 10^21
yotta(17) -- 10^24
}

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

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)'.

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.

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 }

EntPhySensorEntry ::= SEQUENCE {
entPhySensorType EntitySensorDataType,
entPhySensorScale EntitySensorDataScale,
entPhySensorPrecision EntitySensorPrecision,
entPhySensorValue EntitySensorValue,
entPhySensorOperStatus EntitySensorStatus,
entPhySensorUnitsDisplay SnmpAdminString,
entPhySensorValueTimeStamp TimeStamp,
entPhySensorValueUpdateRate Unsigned32
}

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 }

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 }

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.

"
::= { entPhySensorEntry 8 }

--
-- Conformance Section
--

entitySensorCompliances OBJECT IDENTIFIER
::= { entitySensorConformance 1 }
entitySensorGroups OBJECT IDENTIFIER
::= { entitySensorConformance 2 }

entitySensorCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"Describes the requirements for conformance to the Entity
Sensor MIB module."
MODULE -- this module
MANDATORY-GROUPS { entitySensorValueGroup }

MODULE ENTITY-MIB
MANDATORY-GROUPS { entityPhysicalGroup }

::= { entitySensorCompliances 1 }

-- Object Groups

entitySensorValueGroup OBJECT-GROUP
OBJECTS {
entPhySensorType,
entPhySensorScale,
entPhySensorPrecision,
entPhySensorValue,
entPhySensorOperStatus,
entPhySensorUnitsDisplay,
entPhySensorValueTimeStamp,
entPhySensorValueUpdateRate
}
STATUS current
DESCRIPTION
"A collection of objects representing physical entity sensor
information."
::= { entitySensorGroups 1 }

END

5. Intellectual Property

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.

The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.

6. Acknowledgements

This memo is a product of the Entity MIB working group. It is based
on an existing proprietary MIB module written by Cliff Sojourner.

7. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, 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, RFC2578, April
1999.

[RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M., and S. Waldbusser, "Textual Conventions for
SMIv2", STD 58, RFC2579, April 1999.

[RFC2580] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M. and S. Waldbusser, "Conformance Statements for
SMIv2", STD 58, RFC2580, April 1999.

[RFC2737] McCloghrie, K. and A. Bierman, "Entity MIB (Version 2)",
RFC2737, 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, RFC3414, 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, RFC3415, December
2002.

8. Informative References

[RFC2819] Waldbusser, S., "Remote network Monitoring Management
Information Base", RFC2819, May 2000.

[RFC3410] Case, J., Mundy, R., Partain, D. and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC3410, December 2002.

9. Security Considerations

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, RFC3414 [RFC3414] and the
View-based Access Control Model STD 62, RFC3415 [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.

10. Authors' Addresses

Andy Bierman
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA USA 95134
Phone: +1 408-527-3711
EMail: abierman@cisco.com

Dan Romascanu
Avaya Inc.
Atidim Technology Park, Bldg. #3
Tel Aviv, 61131, Israel
Phone: +972-3-545-8414
EMail: dromasca@avaya.com

K.C. Norseth
L-3 Communications
640 N. 2200 West.
Salt Lake City, Utah 84116-0850
Phone: +1 801-594-2809
EMail: kenyon.c.norseth@L-3com.com

11. Full Copyright Statement

Copyright (C) The Internet Society (2002). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
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followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
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This document and the information contained herein is provided on an
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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Acknowledgement

Funding for the RFCEditor function is currently provided by the
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