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Versions: 00 01 02 03 04 05 06 RFC 2737

Entity MIB Working Group                               Keith McCloghrie
Internet Draft                                       Cisco Systems, Inc.
                                                           Andy Bierman
                                                     Cisco Systems, Inc.
                                                         22 August 1999

                         Entity MIB (Version 2)

                     <draft-ietf-entmib-v2-06.txt>

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 [RFC2026].

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet- Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Distribution of this document is unlimited. Please send comments to the
Entity MIB Working Group, <entmib@cisco.com>.

1.  Copyright Notice

Copyright (C) The Internet Society (1999).  All Rights Reserved.

Internet-Draft           Entity MIB (Version 2)              August 1999

2.  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 used for managing multiple
logical and physical entities managed by a single SNMP agent.

3.  Table of Contents

1 Copyright Notice ................................................    1
2 Abstract ........................................................    2
3 Table of Contents ...............................................    2
4 The SNMP Management Framework ...................................    3
5 Overview ........................................................    4
5.1 Terms .........................................................    5
5.2 Relationship to Community Strings .............................    6
5.3 Relationship to SNMP Contexts .................................    6
5.4 Relationship to Proxy Mechanisms ..............................    7
5.5 Relationship to a Chassis MIB .................................    7
5.6 Relationship to the Interfaces MIB ............................    7
5.7 Relationship to the Other MIBs ................................    8
5.8 Relationship to Naming Scopes .................................    8
5.9 Multiple Instances of the Entity MIB ..........................    8
5.10 Re-Configuration of Entities .................................    9
5.11 Textual Convention Change ....................................    9
5.12 MIB Structure ................................................   10
5.12.1 entityPhysical Group .......................................   10
5.12.2 entityLogical Group ........................................   11
5.12.3 entityMapping Group ........................................   11
5.12.4 entityGeneral Group ........................................   12
5.12.5 entityNotifications Group ..................................   12
5.13 Multiple Agents ..............................................   12
5.14 Change Log ...................................................   13
5.14.1 Version 00 .................................................   13
5.14.2 Version 01 .................................................   14
5.14.3 Version 02 .................................................   14
5.14.4 Version 03 .................................................   14
5.14.5 Version 04 .................................................   15
5.14.6 Version 05 .................................................   15
5.14.7 Version 06 .................................................   15
6 Definitions .....................................................   16
7 Usage Examples ..................................................   44
7.1 Router/Bridge .................................................   44
7.2 Repeaters .....................................................   50
8 Intellectual Property ...........................................   58
9 Acknowledgements ................................................   58
10 References .....................................................   58

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11 Security Considerations ........................................   62
12 Authors' Addresses .............................................   64
13 Full Copyright Statement .......................................   65

4.  The SNMP Management Framework

   The SNMP Management Framework presently consists of five major
   components:

    o   An overall architecture, described in RFC 2571 [RFC2571].

    o   Mechanisms for describing and naming objects and events for the
        purpose of management. The first version of this Structure of
        Management Information (SMI) is called SMIv1 and described in
        RFC 1155 [RFC1155], RFC 1212 [RFC1212] and RFC 1215 [RFC1215].
        The second version, called SMIv2, is described in RFC 2578
        [RFC2578], RFC 2579 [RFC2579] and RFC 2580 [RFC2580].

    o   Message protocols for transferring management information. The
        first version of the SNMP message protocol is called SNMPv1 and
        described in RFC 1157 [RFC1157]. A second version of the SNMP
        message protocol, which is not an Internet standards track
        protocol, is called SNMPv2c and described in RFC 1901 [RFC1901]
        and RFC 1906 [RFC1906]. The third version of the message
        protocol is called SNMPv3 and described in RFC 1906 [RFC1906],
        RFC 2572 [RFC2572] and RFC 2574 [RFC2574].

    o   Protocol operations for accessing management information. The
        first set of protocol operations and associated PDU formats is
        described in RFC 1157 [RFC1157]. A second set of protocol
        operations and associated PDU formats is described in RFC 1905
        [RFC1905].

    o   A set of fundamental applications described in RFC 2573
        [RFC2573] and the view-based access control mechanism described
        in RFC 2575 [RFC2575].

   A more detailed introduction to the current SNMP Management Framework
   can be found in RFC 2570 [RFC2570].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   This memo specifies a MIB module that is compliant to the SMIv2. A

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   MIB conforming to the SMIv1 can be produced through the appropriate
   translations. The resulting translated MIB must be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64). Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process. However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.

5.  Overview

There is a need for a standardized way of representing a single agent
which supports multiple instances of one MIB.  This is presently true
for at least 3 standard MIBs, and is likely to become true for more and
more MIBs as time passes.  For example:

   - multiple instances of a bridge supported within a single device
     having a single agent;

   - multiple repeaters supported by a single agent;

   - multiple OSPF backbone areas, each one operating as part of its own
     Autonomous System, and each identified by the same area-id (e.g.,
     0.0.0.0), supported inside a single router with one agent.

The fact that it is a single agent in each of these cases implies there
is some relationship which binds all of these entities together.
Effectively, there is some "overall" physical entity which houses the
sum of the things managed by that one agent, i.e., there are multiple
"logical" entities within a single physical entity.  Sometimes, the
overall physical entity contains multiple (smaller) physical entities
and each logical entity is associated with a particular physical entity.
Sometimes, the overall physical entity is a "compound" of multiple
physical entities (e.g., a stack of stackable hubs).

What is needed is a way to determine exactly what logical entities are
managed by the agent (with some version of SNMP), and thereby to be able
to communicate with the agent about a particular logical entity.  When
different logical entities are associated with different physical
entities within the overall physical entity, it is also useful to be
able to use this information to distinguish between logical entities.

In these situations, there is no need for varbinds for multiple logical
entities to be referenced in the same SNMP message (although that might
be useful in the future).  Rather, it is sufficient, and in some

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situations preferable, to have the context/community in the message
identify the logical entity to which the varbinds apply.

Version 2 of this MIB addresses new requirements that have emerged since
the publication of the first Entity MIB (RFC 2037 [RFC2037]).  There is
a need for a standardized way of providing non-volatile,
administratively assigned identifiers for physical components
represented with the Entity MIB.  There is also a need to align the
Entity MIB with the SNMPv3 administrative framework (RFC 2571
[RFC2571]). Implementation experience has shown that additional physical
component attributes are also desirable.

5.1.  Terms

Some new terms are used throughout this document:

   - Naming Scope
     A "naming scope" represents the set of information that may be
     potentially accessed through a single SNMP operation. All instances
     within the naming scope share the same unique identifier space.
     For SNMPv1, a naming scope is identified by the value of the
     associated 'entLogicalCommunity' instance.  For SNMPv3, the term
     'context' is used instead of 'naming scope'.  The complete
     definition of an SNMP context can be found in section 3.3.1 of RFC
     2571 [RFC2571].

   - Multi-Scoped Object
     A MIB object, for which identical instance values identify
     different managed information in different naming scopes, is called
     a "multi-scoped" MIB object.

   - Single-Scoped Object
     A MIB object, for which identical instance values identify the same
     managed information in different naming scopes, is called a
     "single-scoped" MIB object.

   - Logical Entity
     A managed system contains one or more logical entities, each
     represented by at most one instantiation of each of a particular
     set of MIB objects.  A set of management functions is associated
     with each logical entity. Examples of logical entities include
     routers, bridges, print-servers, etc.

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   - Physical Entity
     A "physical entity" or "physical component" represents an
     identifiable physical resource within a managed system. Zero or
     more logical entities may utilize a physical resource at any given
     time. It is an implementation-specific manner as to which physical
     components are represented by an agent in the EntPhysicalTable.
     Typically, physical resources (e.g., communications ports,
     backplanes, sensors, daughter-cards, power supplies, the overall
     chassis) which can be managed via functions associated with one or
     more logical entities are included in the MIB.

   - Containment Tree
     Each physical component may be modeled as 'contained' within
     another physical component. A "containment-tree" is the conceptual
     sequence of entPhysicalIndex values which uniquely specifies the
     exact physical location of a physical component within the managed
     system.  It is generated by 'following and recording' each
     'entPhysicalContainedIn' instance 'up the tree towards the root',
     until a value of zero indicating no further containment is found.

5.2.  Relationship to Community Strings

For community-based SNMP, distinguishing between different logical
entities is one (but not the only) purpose of the community string (RFC
1157 [RFC1157]).  This is accommodated by representing each community
string as a logical entity.

Note that different logical entities may share the same naming scope
(and therefore the same values of entLogicalCommunity). This is
possible, providing they have no need for the same instance of a MIB
object to represent different managed information.

5.3.  Relationship to SNMP Contexts

Version 2 of the Entity MIB contains support for associating SNMPv3
contexts with logical entities. Two new MIB objects, defining an
SnmpEngineID and ContextName pair, are used together to identify an SNMP
context associated with a logical entity. This context can be used (in
conjunction with the entLogicalTAddress and entLogicalTDomain MIB
objects) to send SNMPv3 messages on behalf of a particular logical
entity.

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5.4.  Relationship to Proxy Mechanisms

The Entity MIB is designed to allow functional component discovery.  The
administrative relationships between different logical entities are not
visible in any Entity MIB tables. An NMS cannot determine whether MIB
instances in different naming scopes are realized locally or remotely
(e.g., via some proxy mechanism) by examining any particular Entity MIB
objects.

The management of administrative framework functions is not an explicit
goal of the Entity MIB WG at this time. This new area of functionality
may be revisited after some operational experience with the Entity MIB
is gained.

Note that for community-based versions of SNMP, a network administrator
will likely be able to associate community strings with naming scopes
with proprietary mechanisms, as a matter of configuration.  There are no
mechanisms for managing naming scopes defined in this MIB.

5.5.  Relationship to a Chassis MIB

Some readers may recall that a previous IETF working group attempted to
define a Chassis MIB.  No consensus was reached by that working group,
possibly because its scope was too broad.  As such, it is not the
purpose of this MIB to be a "Chassis MIB replacement", nor is it within
the scope of this MIB to contain all the information which might be
necessary to manage a "chassis".  On the other hand, the entities
represented by an implementation of this MIB might well be contained in
a chassis.

5.6.  Relationship to the Interfaces MIB

The Entity MIB contains a mapping table identifying physical components
that have 'external values' (e.g., ifIndex) associated with them within
a given naming scope.  This table can be used to identify the physical
location of each interface in the ifTable (RFC 2233 [RFC2233]).  Since
ifIndex values in different contexts are not related to one another, the
interface to physical component associations are relative to the same
logical entity within the agent.

The Entity MIB also contains 'entPhysicalName' and 'entPhysicalAlias'
objects, which approximate the semantics of the 'ifName' and 'ifAlias'
objects (respectively) from the Interfaces MIB [RFC2233], for all types

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of physical components.

5.7.  Relationship to the Other MIBs

The Entity MIB contains a mapping table identifying physical components
that have identifiers from other standard MIBs associated with them.
For example, this table can be used along with the physical mapping
table to identify the physical location of each repeater port in the
rptrPortTable, or each interface in the ifTable.

5.8.  Relationship to Naming Scopes

There is some question as to which MIB objects may be returned within a
given naming scope. MIB objects which are not multi-scoped within a
managed system are likely to ignore context information in
implementation. In such a case, it is likely such objects will be
returned in all naming scopes (e.g., not just the 'default' naming scope
or the SNMPv3 default context).

For example, a community string used to access the management
information for logical device 'bridge2' may allow access to all the
non-bridge related objects in the 'default' naming scope, as well as a
second instance of the Bridge MIB (RFC 1493 [RFC1493]).

It is an implementation-specific matter as to the isolation of single-
scoped MIB objects by the agent. An agent may wish to limit the objects
returned in a particular naming scope to just the multi-scoped objects
in that naming scope (e.g., system group and the Bridge MIB).  In this
case, all single-scoped management information would belong to a common
naming scope (e.g., 'default'), which itself may contain some multi-
scoped objects (e.g., system group).

5.9.  Multiple Instances of the Entity MIB

It is possible that more than one agent exists in a managed system, and
in such cases, multiple instances of the Entity MIB (representing the
same managed objects) may be available to an NMS.

In order to reduce complexity for agent implementation, multiple
instances of the Entity MIB are not required to be equivalent or even
consistent. An NMS may be able to 'align' instances returned by
different agents by examining the columns of each table, but vendor-
specific identifiers and (especially) index values are likely to be

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different. Each agent may be managing different subsets of the entire
chassis as well.

When all of a physically-modular device is represented by a single
agent, the entry for which entPhysicalContainedIn has the value zero
would likely have 'chassis' as the value of its entPhysicalClass;
alternatively, for an agent on a module where the agent represents only
the physical entities on that module (not those on other modules), the
entry for which entPhysicalContainedIn has the value zero would likely
have 'module' as the value of its entPhysicalClass.

An agent implementation of the entLogicalTable is not required to
contain information about logical entities managed primarily by other
agents. That is, the entLogicalTAddress and entLogicalTDomain objects in
the entLogicalTable are provided to support an historical multiplexing
mechanism, not to identify other SNMP agents.

Note that the Entity MIB is a single-scoped MIB, in the event an agent
represents the MIB in different naming scopes.

5.10.  Re-Configuration of Entities

Most of the MIB objects defined in this MIB have at most a read-only
MAX-ACCESS clause.  This is a conscious decision by the working group to
limit this MIB's scope.  The second version of the Entity MIB allows a
network administrator to configure some common attributes of physical
components.

5.11.  Textual Convention Change

Version 1 of the Entity MIB contains three MIB objects defined with the
(now obsolete) DisplayString textual convention.  In version 2 of the
Entity MIB, the syntax for these objects has been updated to use the
(now preferred) SnmpAdminString textual convention.

The working group realizes that this change is not strictly supported by
SMIv2.  In our judgment, the alternative of deprecating the old objects
and defining new objects would have a more adverse impact on backward
compatibility and interoperability, given the particular semantics of
these objects.

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5.12.  MIB Structure

The Entity MIB contains five groups of MIB objects:

  - entityPhysical group
     Describes the physical entities managed by a single agent.

  - entityLogical group
     Describes the logical entities managed by a single agent.

  - entityMapping group
     Describes the associations between the physical entities, logical
     entities, interfaces, and non-interface ports managed by a single
     agent.

  - entityGeneral group
     Describes general system attributes shared by potentially all types
     of entities managed by a single agent.

  - entityNotifications group
     Contains status indication notifications.

5.12.1.  entityPhysical Group

This group contains a single table to identify physical system
components, called the entPhysicalTable.

The entPhysicalTable contains one row per physical entity, and must
always contain at least one row for an "overall" physical entity, which
should have an entPhysicalClass value of 'stack(11)', 'chassis(3)' or
'module(9)'.

Each row is indexed by an arbitrary, small integer, and contains a
description and type of the physical entity.  It also optionally
contains the index number of another entPhysicalEntry indicating a
containment relationship between the two.

Version 2 of the Entity MIB provides additional MIB objects for each
physical entity. Some common read-only attributes have been added, as
well as three writable string objects.

  - entPhysicalAlias
     This string can be used by an NMS as a non-volatile identifier for
     the physical component. Maintaining a non-volatile string for every
     physical component represented in the entPhysicalTable can be

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     costly and unnecessary.  An agent may algorithmically generate
     'entPhysicalAlias' strings for particular entries (e.g., based on
     the entPhysicalClass value).

  - entPhysicalAssetID
     This string is provided to store a user-specific asset identifier
     for removable physical components.  In order to reduce the non-
     volatile storage needed by a particular agent, a network
     administrator should only assign asset identifiers to physical
     entities which are field-replaceable (i.e., not permanently
     contained within another physical entity).

  - entPhysicalSerialNum
     This string is provided to store a vendor-specific serial number
     string for physical components.  This is a writable object in case
     an agent cannot identify the serial numbers of all installed
     physical entities, and a network administrator wishes to configure
     the non-volatile serial number strings manually (via an NMS
     application).

5.12.2.  entityLogical Group

This group contains a single table to identify logical entities, called
the entLogicalTable.

The entLogicalTable contains one row per logical entity.  Each row is
indexed by an arbitrary, small integer and contains a name, description,
and type of the logical entity. It also contains information to allow
access to the MIB information for the logical entity. This includes SNMP
versions that use a community name (with some form of implied context
representation) and SNMP versions that use the SNMP ARCH [RFC2571]
method of context identification.

If a agent represents multiple logical entities with this MIB, then this
group must be implemented for all logical entities known to the agent.

If an agent represents a single logical entity, or multiple logical
entities within a single naming scope, then implementation of this group
may be omitted by the agent.

5.12.3.  entityMapping Group

This group contains three tables to identify associations between
different system components.

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The entLPMappingTable contains mappings between entLogicalIndex values
(logical entities) and entPhysicalIndex values (the physical components
supporting that entity). A logical entity can map to more than one
physical component, and more than one logical entity can map to (share)
the same physical component.  If an agent represents a single logical
entity, or multiple logical entities within a single naming scope, then
implementation of this table may be omitted by the agent.

The entAliasMappingTable contains mappings between entLogicalIndex,
entPhysicalIndex pairs and 'alias' object identifier values.  This
allows resources managed with other MIBs (e.g., repeater ports, bridge
ports, physical and logical interfaces) to be identified in the physical
entity hierarchy. Note that each alias identifier is only relevant in a
particular naming scope.  If an agent represents a single logical
entity, or multiple logical entities within a single naming scope, then
implementation of this table may be omitted by the agent.

The entPhysicalContainsTable contains simple mappings between
'entPhysicalContainedIn' values for each container/'containee'
relationship in the managed system. The indexing of this table allows an
NMS to quickly discover the 'entPhysicalIndex' values for all children
of a given physical entity.

5.12.4.  entityGeneral Group

This group contains general information relating to the other object
groups.

At this time, the entGeneral group contains a single scalar object
(entLastChangeTime), which represents the value of sysUptime when any
part of the Entity MIB configuration last changed.

5.12.5.  entityNotifications Group

This group contains notification definitions relating to the overall
status of the Entity MIB instantiation.

5.13.  Multiple Agents

Even though a primary motivation for this MIB is to represent the
multiple logical entities supported by a single agent, it is also
possible to use it to represent multiple logical entities supported by
multiple agents (in the same "overall" physical entity).  Indeed, it is
implicit in the SNMP architecture, that the number of agents is
transparent to a network management station.

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However, there is no agreement at this time as to the degree of
cooperation which should be expected for agent implementations.
Therefore, multiple agents within the same managed system are free to
implement the Entity MIB independently.  (Refer the section on "Multiple
Instances of the Entity MIB" for more details).

5.14.  Change Log

The following changes have been made since publication of the original
Entity MIB [RFC2037].

5.14.1.  Version 00

  -  Clarified description of the PhysicalClass textual convention.
     Added a new enumeration.

  -  Added RevisionString and SnmpEngineIdOrZero textual conventions to
     support new entPhysicalTable and entLogicalTable objects

  -  Fixed bug in entPhysicalParentRelPos DESCRIPTION clause

  -  Added entPhysicalHardwareRev, FirmwareRev, and SoftwareRev objects
     for revision identification

  -  Added entPhysicalMfgName and entPhysicalModelName objects for
     better component identification

  -  Added entPhysicalAlias read-write string to identify specific
     components across reboots.

  -  Added entPhysicalAssetID and entPhysicalSerialNum read-write
     strings to allow user identification of specific components across
     reboots.

  -  Fixed a bug in the entLogicalCommunity object. The subrange was
     incorrect (1..255) and is now (0..255).  The description clause has
     also been clarified.  This object is now deprecated.

  -  Added entLogicalContextEngineID and entLogicalContextName objects
     to provide an SNMP context for SNMPv3 access on behalf of a logical
     entity.

  -  Changed entLastChangeTime object description to generalize the
     events which cause an update to the last change timestamp.

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5.14.2.  Version 01

  -  Removed the RevisionString TC.

  -  Changed the entPhysicalHardwareRev, entPhysicalFirmwareRev, and
     entPhysicalSoftwareRev SYNTAX from RevisionString to
     SnmpAdminString

  -  Made logical entity objects optional for agents with a single
     'default naming scope'

  -  Fixed conformance section bugs

  -  Clarified containment rules for removable physical components

5.14.3.  Version 02

  -  Added term definition for 'parent entity'.

  -  Added entPhysicalIsFRU object.

  -  Clarify modeling double-high modules.

  -  Clarify scope of some entPhysicalEntry attributes.

  -  Clarify instantiation guidelines of some entPhysicalTable strings.

  -  Fix typos and deleted some obsolete intro text.

  -  Relax trap throttling requirement from 'must' to 'should'.

  -  Change instances of the term 'trap' to 'notification', to align
     with SNMPv3 terminology.

  -  Update Usage Examples section for Version 2 objects.

5.14.4.  Version 03

  -  Added REVISION clauses to the MIB.

  -  Removed language allowing an agent to omit certain SnmpAdminString
     based MIB instances.  A zero-length string string must be returned
     instead.

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  -  Updated I-D boilerplate.

  -  Updated reference identification format.

5.14.5.  Version 04

  -  Updated SNMP boilerplate and references.

  -  Changed 'main' naming scope to 'default' naming scope to be more
     consistent with SNMPv3 default context.

  -  Removed the 'in-progress' REVISION clauses from the MIB.

  -  Updated Security Considerations section.

  -  Clarified some text regarding specific versions of SNMP.

5.14.6.  Version 05

  -  Shortened the document title.

  -  Renamed the SnmpEngineIdOrZero TC to be SnmpEngineIdOrNone.

  -  Changed the entLogicalContextEngineID SYNTAX to SnmpEngineIdOrNone.

  -  Clarified description of the SnmpEngineIdOrNone TC for zero-length
     strings.

5.14.7.  Version 06

  -  Changed syntax from DisplayString to SnmpAdminString for the
     entPhysicalDescr, entPhysicalName, and entLogicalDescr objects.

  -  Removed DisplayString from the IMPORTS clause.

  -  Added 'Textual Convention Change' section, which documents this
     change.

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6.  Definitions

ENTITY-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, mib-2, NOTIFICATION-TYPE
        FROM SNMPv2-SMI
    TDomain, TAddress, TEXTUAL-CONVENTION,
    AutonomousType, RowPointer, TimeStamp, TruthValue
        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
        FROM SNMPv2-CONF
    SnmpAdminString
        FROM SNMP-FRAMEWORK-MIB;

entityMIB MODULE-IDENTITY
    LAST-UPDATED "9908220000Z"
    ORGANIZATION "IETF ENTMIB Working Group"
    CONTACT-INFO
            "        WG E-mail: entmib@cisco.com
                  Subscribe: majordomo@cisco.com
                         msg body: subscribe entmib

                     Keith McCloghrie
                     ENTMIB Working Group Chair
                     Cisco Systems Inc.
                     170 West Tasman Drive
                     San Jose, CA 95134
                     +1 408-526-5260
                     kzm@cisco.com

                     Andy Bierman
                     ENTMIB Working Group Editor
                     Cisco Systems Inc.
                     170 West Tasman Drive
                     San Jose, CA 95134
                     +1 408-527-3711
                     abierman@cisco.com"
    DESCRIPTION
            "The MIB module for representing multiple logical
            entities supported by a single SNMP agent."
    REVISION        "9908220000Z"
    DESCRIPTION
            "Initial Version of Entity MIB (Version 2).
             This revision obsoletes RFC 2037.

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             This version published as RFC xxxx (to be
             assigned by the RFC Editor)."
    REVISION        "9610310000Z"
    DESCRIPTION
            "Initial version (version 1), published as
             RFC 2037."
    ::= { mib-2 47 }

entityMIBObjects OBJECT IDENTIFIER ::= { entityMIB 1 }

-- MIB contains four groups
entityPhysical OBJECT IDENTIFIER ::= { entityMIBObjects 1 }
entityLogical  OBJECT IDENTIFIER ::= { entityMIBObjects 2 }
entityMapping  OBJECT IDENTIFIER ::= { entityMIBObjects 3 }
entityGeneral  OBJECT IDENTIFIER ::= { entityMIBObjects 4 }

-- Textual Conventions
PhysicalIndex ::= TEXTUAL-CONVENTION
    STATUS            current
    DESCRIPTION
            "An arbitrary value which uniquely identifies the physical
            entity.  The value should be a small positive integer; index
            values for different physical entities are not necessarily
            contiguous."
    SYNTAX INTEGER (1..2147483647)

PhysicalClass ::= TEXTUAL-CONVENTION
    STATUS            current
    DESCRIPTION
            "An enumerated value which provides an indication of the
            general hardware type of a particular physical entity.
            There are no restrictions as to the number of
            entPhysicalEntries of each entPhysicalClass, which must be
            instantiated by an agent.

            The enumeration 'other' is applicable if the physical entity
            class is known, but does not match any of the supported
            values.

            The enumeration 'unknown' is applicable if the physical
            entity class is unknown to the agent.

            The enumeration 'chassis' is applicable if the physical

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            entity class is an overall container for networking
            equipment.  Any class of physical entity except a stack may
            be contained within a chassis, and a chassis may only be
            contained within a stack.

            The enumeration 'backplane' is applicable if the physical
            entity class is some sort of device for aggregating and
            forwarding networking traffic, such as a shared backplane in
            a modular ethernet switch.  Note that an agent may model a
            backplane as a single physical entity, which is actually
            implemented as multiple discrete physical components (within
            a chassis or stack).

            The enumeration 'container' is applicable if the physical
            entity class is capable of containing one or more removable
            physical entities, possibly of different types. For example,
            each (empty or full) slot in a chassis will be modeled as a
            container. Note that all removable physical entities should
            be modeled within a container entity, such as field-
            replaceable modules, fans, or power supplies.  Note that all
            known containers should be modeled by the agent, including
            empty containers.

            The enumeration 'powerSupply' is applicable if the physical
            entity class is a power-supplying component.

            The enumeration 'fan' is applicable if the physical entity
            class is a fan or other heat-reduction component.

            The enumeration 'sensor' is applicable if the physical
            entity class is some sort of sensor, such as a temperature
            sensor within a router chassis.

            The enumeration 'module' is applicable if the physical
            entity class is some sort of self-contained sub-system.  If
            it is removable, then it should be modeled within a
            container entity, otherwise it should be modeled directly
            within another physical entity (e.g., a chassis or another
            module).

            The enumeration 'port' is applicable if the physical entity
            class is some sort of networking port, capable of receiving
            and/or transmitting networking traffic.

            The enumeration 'stack' is applicable if the physical entity

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            class is some sort of super-container (possibly virtual),
            intended to group together multiple chassis entities.  A
            stack may be realized by a 'virtual' cable, a real
            interconnect cable, attached to multiple chassis, or may in
            fact be comprised of multiple interconnect cables. A stack
            should not be modeled within any other physical entities,
            but a stack may be contained within another stack.  Only
            chassis entities should be contained within a stack."
    SYNTAX      INTEGER  {
       other(1),
       unknown(2),
       chassis(3),
       backplane(4),
       container(5),     -- e.g., chassis slot or daughter-card holder
       powerSupply(6),
       fan(7),
       sensor(8),
       module(9),        -- e.g., plug-in card or daughter-card
       port(10),
       stack(11)         -- e.g., stack of multiple chassis entities
    }

SnmpEngineIdOrNone ::= TEXTUAL-CONVENTION
    STATUS            current
    DESCRIPTION
            "A specially formatted SnmpEngineID string for use with the
            Entity MIB.

            If an instance of an object of SYNTAX SnmpEngineIdOrNone has
            a non-zero length, then the object encoding and semantics
            are defined by the SnmpEngineID textual convention (see RFC
            2571 [RFC2571]).

            If an instance of an object of SYNTAX SnmpEngineIdOrNone
            contains a zero-length string, then no appropriate
            SnmpEngineID is associated with the logical entity (i.e.,
            SNMPv3 not supported)."
    SYNTAX OCTET STRING (SIZE(0..32)) -- empty string or SnmpEngineID

--           The Physical Entity Table
entPhysicalTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF EntPhysicalEntry
    MAX-ACCESS  not-accessible
    STATUS      current

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    DESCRIPTION
            "This table contains one row per physical entity.  There is
            always at least one row for an 'overall' physical entity."
    ::= { entityPhysical 1 }

entPhysicalEntry       OBJECT-TYPE
    SYNTAX      EntPhysicalEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "Information about a particular physical entity.

            Each entry provides objects (entPhysicalDescr,
            entPhysicalVendorType, and entPhysicalClass) to help an NMS
            identify and characterize the entry, and objects
            (entPhysicalContainedIn and entPhysicalParentRelPos) to help
            an NMS relate the particular entry to other entries in this
            table."
    INDEX   { entPhysicalIndex }
    ::= { entPhysicalTable 1 }

EntPhysicalEntry ::= SEQUENCE {
      entPhysicalIndex          PhysicalIndex,
      entPhysicalDescr          SnmpAdminString,
      entPhysicalVendorType     AutonomousType,
      entPhysicalContainedIn    INTEGER,
      entPhysicalClass          PhysicalClass,
      entPhysicalParentRelPos   INTEGER,
      entPhysicalName           SnmpAdminString,
      entPhysicalHardwareRev    SnmpAdminString,
      entPhysicalFirmwareRev    SnmpAdminString,
      entPhysicalSoftwareRev    SnmpAdminString,
      entPhysicalSerialNum      SnmpAdminString,
      entPhysicalMfgName        SnmpAdminString,
      entPhysicalModelName      SnmpAdminString,
      entPhysicalAlias          SnmpAdminString,
      entPhysicalAssetID        SnmpAdminString,
      entPhysicalIsFRU          TruthValue
}

entPhysicalIndex    OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION

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            "The index for this entry."
    ::= { entPhysicalEntry 1 }

entPhysicalDescr OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "A textual description of physical entity.  This object
            should contain a string which identifies the manufacturer's
            name for the physical entity, and should be set to a
            distinct value for each version or model of the physical
            entity. "
    ::= { entPhysicalEntry 2 }

entPhysicalVendorType OBJECT-TYPE
    SYNTAX      AutonomousType
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the vendor-specific hardware type of the
            physical entity.  Note that this is different from the
            definition of MIB-II's sysObjectID.

            An agent should set this object to a enterprise-specific
            registration identifier value indicating the specific
            equipment type in detail.  The associated instance of
            entPhysicalClass is used to indicate the general type of
            hardware device.

            If no vendor-specific registration identifier exists for
            this physical entity, or the value is unknown by this agent,
            then the value { 0 0 } is returned."
    ::= { entPhysicalEntry 3 }

entPhysicalContainedIn OBJECT-TYPE
    SYNTAX      INTEGER (0..2147483647)
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of entPhysicalIndex for the physical entity which
            'contains' this physical entity.  A value of zero indicates
            this physical entity is not contained in any other physical
            entity.  Note that the set of 'containment' relationships
            define a strict hierarchy; that is, recursion is not

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            allowed.

            In the event a physical entity is contained by more than one
            physical entity (e.g., double-wide modules), this object
            should identify the containing entity with the lowest value
            of entPhysicalIndex."
    ::= { entPhysicalEntry 4 }

entPhysicalClass OBJECT-TYPE
    SYNTAX      PhysicalClass
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the general hardware type of the physical
            entity.

            An agent should set this object to the standard enumeration
            value which most accurately indicates the general class of
            the physical entity, or the primary class if there is more
            than one.

            If no appropriate standard registration identifier exists
            for this physical entity, then the value 'other(1)' is
            returned. If the value is unknown by this agent, then the
            value 'unknown(2)' is returned."
    ::= { entPhysicalEntry 5 }

entPhysicalParentRelPos OBJECT-TYPE
    SYNTAX      INTEGER (-1..2147483647)
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the relative position of this 'child'
            component among all its 'sibling' components. Sibling
            components are defined as entPhysicalEntries which share the
            same instance values of each of the entPhysicalContainedIn
            and entPhysicalClass objects.

            An NMS can use this object to identify the relative ordering
            for all sibling components of a particular parent
            (identified by the entPhysicalContainedIn instance in each
            sibling entry).

            This value should match any external labeling of the
            physical component if possible. For example, for a container

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            (e.g., card slot) labeled as 'slot #3',
            entPhysicalParentRelPos should have the value '3'.  Note
            that the entPhysicalEntry for the module plugged in slot 3
            should have an entPhysicalParentRelPos value of '1'.

            If the physical position of this component does not match
            any external numbering or clearly visible ordering, then
            user documentation or other external reference material
            should be used to determine the parent-relative position. If
            this is not possible, then the the agent should assign a
            consistent (but possibly arbitrary) ordering to a given set
            of 'sibling' components, perhaps based on internal
            representation of the components.

            If the agent cannot determine the parent-relative position
            for some reason, or if the associated value of
            entPhysicalContainedIn is '0', then the value '-1' is
            returned. Otherwise a non-negative integer is returned,
            indicating the parent-relative position of this physical
            entity.

            Parent-relative ordering normally starts from '1' and
            continues to 'N', where 'N' represents the highest
            positioned child entity.  However, if the physical entities
            (e.g., slots) are labeled from a starting position of zero,
            then the first sibling should be associated with a
            entPhysicalParentRelPos value of '0'.  Note that this
            ordering may be sparse or dense, depending on agent
            implementation.

            The actual values returned are not globally meaningful, as
            each 'parent' component may use different numbering
            algorithms. The ordering is only meaningful among siblings
            of the same parent component.

            The agent should retain parent-relative position values
            across reboots, either through algorithmic assignment or use
            of non-volatile storage."
    ::= { entPhysicalEntry 6 }

entPhysicalName OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION

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            "The textual name of the physical entity.  The value of this
            object should be the name of the component as assigned by
            the local device and should be suitable for use in commands
            entered at the device's `console'.  This might be a text
            name, such as `console' or a simple component number (e.g.,
            port or module number), such as `1', depending on the
            physical component naming syntax of the device.

            If there is no local name, or this object is otherwise not
            applicable, then this object contains a zero-length string.

            Note that the value of entPhysicalName for two physical
            entities will be the same in the event that the console
            interface does not distinguish between them, e.g., slot-1
            and the card in slot-1."
    ::= { entPhysicalEntry 7 }

entPhysicalHardwareRev    OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The vendor-specific hardware revision string for the
            physical entity.  The preferred value is the hardware
            revision identifier actually printed on the component itself
            (if present).

            Note that if revision information is stored internally in a
            non-printable (e.g., binary) format, then the agent must
            convert such information to a printable format, in an
            implementation-specific manner.

            If no specific hardware revision string is associated with
            the physical component, or this information is unknown to
            the agent, then this object will contain a zero-length
            string."
    ::= { entPhysicalEntry 8 }

entPhysicalFirmwareRev    OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The vendor-specific firmware revision string for the
            physical entity.

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            Note that if revision information is stored internally in a
            non-printable (e.g., binary) format, then the agent must
            convert such information to a printable format, in an
            implementation-specific manner.

            If no specific firmware programs are associated with the
            physical component, or this information is unknown to the
            agent, then this object will contain a zero-length string."
    ::= { entPhysicalEntry 9 }

entPhysicalSoftwareRev    OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The vendor-specific software revision string for the
            physical entity.

            Note that if revision information is stored internally in a
            non-printable (e.g., binary) format, then the agent must
            convert such information to a printable format, in an
            implementation-specific manner.

            If no specific software programs are associated with the
            physical component, or this information is unknown to the
            agent, then this object will contain a zero-length string."
    ::= { entPhysicalEntry 10 }

entPhysicalSerialNum   OBJECT-TYPE
    SYNTAX      SnmpAdminString (SIZE (0..32))
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "The vendor-specific serial number string for the physical
            entity.  The preferred value is the serial number string
            actually printed on the component itself (if present).

            On the first instantiation of an physical entity, the value
            of entPhysicalSerialNum associated with that entity is set
            to the correct vendor-assigned serial number, if this
            information is available to the agent.  If a serial number
            is unknown or non-existent, the entPhysicalSerialNum will be
            set to a zero-length string instead.

            Note that implementations which can correctly identify the

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            serial numbers of all installed physical entities do not
            need to provide write access to the entPhysicalSerialNum
            object. Agents which cannot provide non-volatile storage for
            the entPhysicalSerialNum strings are not required to
            implement write access for this object.

            Not every physical component will have a serial number, or
            even need one.  Physical entities for which the associated
            value of the entPhysicalIsFRU object is equal to 'false(2)'
            (e.g., the repeater ports within a repeater module), do not
            need their own unique serial number. An agent does not have
            to provide write access for such entities, and may return a
            zero-length string.

            If write access is implemented for an instance of
            entPhysicalSerialNum, and a value is written into the
            instance, the agent must retain the supplied value in the
            entPhysicalSerialNum instance associated with the same
            physical entity for as long as that entity remains
            instantiated. This includes instantiations across all re-
            initializations/reboots of the network management system,
            including those which result in a change of the physical
            entity's entPhysicalIndex value."
    ::= { entPhysicalEntry 11 }

entPhysicalMfgName   OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The name of the manufacturer of this physical component.
            The preferred value is the manufacturer name string actually
            printed on the component itself (if present).

            Note that comparisons between instances of the
            entPhysicalModelName, entPhysicalFirmwareRev,
            entPhysicalSoftwareRev, and the entPhysicalSerialNum
            objects, are only meaningful amongst entPhysicalEntries with
            the same value of entPhysicalMfgName.

            If the manufacturer name string associated with the physical
            component is unknown to the agent, then this object will
            contain a zero-length string."
    ::= { entPhysicalEntry 12 }

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entPhysicalModelName   OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The vendor-specific model name identifier string associated
            with this physical component.  The preferred value is the
            customer-visible part number, which may be printed on the
            component itself.

            If the model name string associated with the physical
            component is unknown to the agent, then this object will
            contain a zero-length string."
    ::= { entPhysicalEntry 13 }

entPhysicalAlias    OBJECT-TYPE
    SYNTAX      SnmpAdminString (SIZE (0..32))
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "This object is an 'alias' name for the physical entity as
            specified by a network manager, and provides a non-volatile
            'handle' for the physical entity.

            On the first instantiation of an physical entity, the value
            of entPhysicalAlias associated with that entity is set to
            the zero-length string.  However, agent may set the value to
            a locally unique default value, instead of a zero-length
            string.

            If write access is implemented for an instance of
            entPhysicalAlias, and a value is written into the instance,
            the agent must retain the supplied value in the
            entPhysicalAlias instance associated with the same physical
            entity for as long as that entity remains instantiated.
            This includes instantiations across all re-
            initializations/reboots of the network management system,
            including those which result in a change of the physical
            entity's entPhysicalIndex value."
    ::= { entPhysicalEntry 14 }

entPhysicalAssetID OBJECT-TYPE
    SYNTAX      SnmpAdminString (SIZE (0..32))
    MAX-ACCESS  read-write
    STATUS      current

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    DESCRIPTION
            "This object is a user-assigned asset tracking identifier
            for the physical entity as specified by a network manager,
            and provides non-volatile storage of this information.

            On the first instantiation of an physical entity, the value
            of entPhysicalAssetID associated with that entity is set to
            the zero-length string.

            Not every physical component will have a asset tracking
            identifier, or even need one.  Physical entities for which
            the associated value of the entPhysicalIsFRU object is equal
            to 'false(2)' (e.g., the repeater ports within a repeater
            module), do not need their own unique asset tracking
            identifier. An agent does not have to provide write access
            for such entities, and may instead return a zero-length
            string.

            If write access is implemented for an instance of
            entPhysicalAssetID, and a value is written into the
            instance, the agent must retain the supplied value in the
            entPhysicalAssetID instance associated with the same
            physical entity for as long as that entity remains
            instantiated.  This includes instantiations across all re-
            initializations/reboots of the network management system,
            including those which result in a change of the physical
            entity's entPhysicalIndex value.

            If no asset tracking information is associated with the
            physical component, then this object will contain a zero-
            length string."
    ::= { entPhysicalEntry 15 }

entPhysicalIsFRU OBJECT-TYPE
    SYNTAX      TruthValue
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object indicates whether or not this physical entity
            is considered a 'field replaceable unit' by the vendor.  If
            this object contains the value 'true(1)' then this
            entPhysicalEntry identifies a field replaceable unit.  For
            all entPhysicalEntries which represent components that are
            permanently contained within a field replaceable unit, the
            value 'false(2)' should be returned for this object."

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    ::= { entPhysicalEntry 16 }

--           The Logical Entity Table
entLogicalTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF EntLogicalEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "This table contains one row per logical entity.  For agents
            which implement more than one naming scope, at least one
            entry must exist. Agents which instantiate all MIB objects
            within a single naming scope are not required to implement
            this table."
    ::= { entityLogical 1 }

entLogicalEntry       OBJECT-TYPE
    SYNTAX      EntLogicalEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "Information about a particular logical entity.  Entities
            may be managed by this agent or other SNMP agents (possibly)
            in the same chassis."
    INDEX       { entLogicalIndex }
    ::= { entLogicalTable 1 }

EntLogicalEntry ::= SEQUENCE {
      entLogicalIndex            INTEGER,
      entLogicalDescr            SnmpAdminString,
      entLogicalType             AutonomousType,
      entLogicalCommunity        OCTET STRING,
      entLogicalTAddress         TAddress,
      entLogicalTDomain          TDomain,
      entLogicalContextEngineID  SnmpEngineIdOrNone,
      entLogicalContextName      SnmpAdminString
}

entLogicalIndex OBJECT-TYPE
    SYNTAX      INTEGER (1..2147483647)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The value of this object uniquely identifies the logical
            entity. The value should be a small positive integer; index

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            values for different logical entities are are not
            necessarily contiguous."
    ::= { entLogicalEntry 1 }

entLogicalDescr OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "A textual description of the logical entity.  This object
            should contain a string which identifies the manufacturer's
            name for the logical entity, and should be set to a distinct
            value for each version of the logical entity. "
    ::= { entLogicalEntry 2 }

entLogicalType OBJECT-TYPE
    SYNTAX      AutonomousType
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the type of logical entity.  This will
            typically be the OBJECT IDENTIFIER name of the node in the
            SMI's naming hierarchy which represents the major MIB
            module, or the majority of the MIB modules, supported by the
            logical entity.  For example:
               a logical entity of a regular host/router -> mib-2
               a logical entity of a 802.1d bridge -> dot1dBridge
               a logical entity of a 802.3 repeater -> snmpDot3RptrMgmt
            If an appropriate node in the SMI's naming hierarchy cannot
            be identified, the value 'mib-2' should be used."
    ::= { entLogicalEntry 3 }

entLogicalCommunity OBJECT-TYPE
    SYNTAX      OCTET STRING (SIZE (0..255))
    MAX-ACCESS  read-only
    STATUS      deprecated
    DESCRIPTION
            "An SNMPv1 or SNMPv2C community-string which can be used to
            access detailed management information for this logical
            entity.  The agent should allow read access with this
            community string (to an appropriate subset of all managed
            objects) and may also return a community string based on the
            privileges of the request used to read this object.  Note
            that an agent may return a community string with read-only
            privileges, even if this object is accessed with a read-

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            write community string. However, the agent must take care
            not to return a community string which allows more
            privileges than the community string used to access this
            object.

            A compliant SNMP agent may wish to conserve naming scopes by
            representing multiple logical entities in a single 'default'
            naming scope.  This is possible when the logical entities
            represented by the same value of entLogicalCommunity have no
            object instances in common.  For example, 'bridge1' and
            'repeater1' may be part of the main naming scope, but at
            least one additional community string is needed to represent
            'bridge2' and 'repeater2'.

            Logical entities 'bridge1' and 'repeater1' would be
            represented by sysOREntries associated with the 'default'
            naming scope.

            For agents not accessible via SNMPv1 or SNMPv2C, the value
            of this object is the empty string.  This object may also
            contain an empty string if a community string has not yet
            been assigned by the agent, or no community string with
            suitable access rights can be returned for a particular SNMP
            request.

            Note that this object is deprecated. Agents which implement
            SNMPv3 access should use the entLogicalContextEngineID and
            entLogicalContextName objects to identify the context
            associated with each logical entity.  SNMPv3 agents may
            return a zero-length string for this object, or may continue
            to return a community string (e.g., tri-lingual agent
            support)."
    ::= { entLogicalEntry 4 }

entLogicalTAddress OBJECT-TYPE
    SYNTAX      TAddress
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The transport service address by which the logical entity
            receives network management traffic, formatted according to
            the corresponding value of entLogicalTDomain.

            For snmpUDPDomain, a TAddress is 6 octets long, the initial
            4 octets containing the IP-address in network-byte order and

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            the last 2 containing the UDP port in network-byte order.
            Consult 'Transport Mappings for Version 2 of the Simple
            Network Management Protocol' (RFC 1906 [RFC1906]) for
            further information on snmpUDPDomain."
    ::= { entLogicalEntry 5 }

entLogicalTDomain OBJECT-TYPE
    SYNTAX      TDomain
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "Indicates the kind of transport service by which the
            logical entity receives network management traffic.
            Possible values for this object are presently found in the
            Transport Mappings for SNMPv2 document (RFC 1906
            [RFC1906])."
    ::= { entLogicalEntry 6 }

entLogicalContextEngineID    OBJECT-TYPE
    SYNTAX      SnmpEngineIdOrNone
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The authoritative contextEngineID that can be used to send
            an SNMP message concerning information held by this logical
            entity, to the address specified by the associated
            'entLogicalTAddress/entLogicalTDomain' pair.

            This object, together with the associated
            entLogicalContextName object, defines the context associated
            with a particular logical entity, and allows access to SNMP
            engines identified by a contextEngineId and contextName
            pair.

            If no value has been configured by the agent, a zero-length
            string is returned, or the agent may choose not to
            instantiate this object at all."
    ::= { entLogicalEntry 7 }

entLogicalContextName    OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The contextName that can be used to send an SNMP message

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            concerning information held by this logical entity, to the
            address specified by the associated
            'entLogicalTAddress/entLogicalTDomain' pair.

            This object, together with the associated
            entLogicalContextEngineID object, defines the context
            associated with a particular logical entity, and allows
            access to SNMP engines identified by a contextEngineId and
            contextName pair.

            If no value has been configured by the agent, a zero-length
            string is returned, or the agent may choose not to
            instantiate this object at all."
    ::= { entLogicalEntry 8 }

entLPMappingTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF EntLPMappingEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "This table contains zero or more rows of logical entity to
            physical equipment associations. For each logical entity
            known by this agent, there are zero or more mappings to the
            physical resources which are used to realize that logical
            entity.

            An agent should limit the number and nature of entries in
            this table such that only meaningful and non-redundant
            information is returned. For example, in a system which
            contains a single power supply, mappings between logical
            entities and the power supply are not useful and should not
            be included.

            Also, only the most appropriate physical component which is
            closest to the root of a particular containment tree should
            be identified in an entLPMapping entry.

            For example, suppose a bridge is realized on a particular
            module, and all ports on that module are ports on this
            bridge. A mapping between the bridge and the module would be
            useful, but additional mappings between the bridge and each
            of the ports on that module would be redundant (since the
            entPhysicalContainedIn hierarchy can provide the same
            information). If, on the other hand, more than one bridge
            was utilizing ports on this module, then mappings between

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            each bridge and the ports it used would be appropriate.

            Also, in the case of a single backplane repeater, a mapping
            for the backplane to the single repeater entity is not
            necessary."
    ::= { entityMapping 1 }

entLPMappingEntry       OBJECT-TYPE
    SYNTAX      EntLPMappingEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "Information about a particular logical entity to physical
            equipment association. Note that the nature of the
            association is not specifically identified in this entry.
            It is expected that sufficient information exists in the
            MIBs used to manage a particular logical entity to infer how
            physical component information is utilized."
    INDEX       { entLogicalIndex, entLPPhysicalIndex }
    ::= { entLPMappingTable 1 }

EntLPMappingEntry ::= SEQUENCE {
      entLPPhysicalIndex         PhysicalIndex
}

entLPPhysicalIndex OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of this object identifies the index value of a
            particular entPhysicalEntry associated with the indicated
            entLogicalEntity."
    ::= { entLPMappingEntry 1 }

-- logical entity/component to alias table
entAliasMappingTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF EntAliasMappingEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "This table contains zero or more rows, representing
            mappings of logical entity and physical component to
            external MIB identifiers.  Each physical port in the system

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            may be associated with a mapping to an external identifier,
            which itself is associated with a particular logical
            entity's naming scope.  A 'wildcard' mechanism is provided
            to indicate that an identifier is associated with more than
            one logical entity."
    ::= { entityMapping 2 }

entAliasMappingEntry       OBJECT-TYPE
    SYNTAX      EntAliasMappingEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "Information about a particular physical equipment, logical
            entity to external identifier binding. Each logical
            entity/physical component pair may be associated with one
            alias mapping.  The logical entity index may also be used as
            a 'wildcard' (refer to the entAliasLogicalIndexOrZero object
            DESCRIPTION clause for details.)

            Note that only entPhysicalIndex values which represent
            physical ports (i.e. associated entPhysicalClass value is
            'port(10)') are permitted to exist in this table."
    INDEX { entPhysicalIndex, entAliasLogicalIndexOrZero }
    ::= { entAliasMappingTable 1 }

EntAliasMappingEntry ::= SEQUENCE {
      entAliasLogicalIndexOrZero        INTEGER,
      entAliasMappingIdentifier          RowPointer
}

entAliasLogicalIndexOrZero OBJECT-TYPE
    SYNTAX      INTEGER (0..2147483647)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The value of this object identifies the logical entity
            which defines the naming scope for the associated instance
            of the 'entAliasMappingIdentifier' object.

            If this object has a non-zero value, then it identifies the
            logical entity named by the same value of entLogicalIndex.

            If this object has a value of zero, then the mapping between
            the physical component and the alias identifier for this
            entAliasMapping entry is associated with all unspecified

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            logical entities. That is, a value of zero (the default
            mapping) identifies any logical entity which does not have
            an explicit entry in this table for a particular
            entPhysicalIndex/entAliasMappingIdentifier pair.

            For example, to indicate that a particular interface (e.g.,
            physical component 33) is identified by the same value of
            ifIndex for all logical entities, the following instance
            might exist:

                    entAliasMappingIdentifier.33.0 = ifIndex.5

            In the event an entPhysicalEntry is associated differently
            for some logical entities, additional entAliasMapping
            entries may exist, e.g.:

                    entAliasMappingIdentifier.33.0 = ifIndex.6
                    entAliasMappingIdentifier.33.4 =  ifIndex.1
                    entAliasMappingIdentifier.33.5 =  ifIndex.1
                    entAliasMappingIdentifier.33.10 = ifIndex.12

            Note that entries with non-zero entAliasLogicalIndexOrZero
            index values have precedence over any zero-indexed entry. In
            this example, all logical entities except 4, 5, and 10,
            associate physical entity 33 with ifIndex.6."
    ::= { entAliasMappingEntry 1 }

entAliasMappingIdentifier OBJECT-TYPE
    SYNTAX      RowPointer
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of this object identifies a particular conceptual
            row associated with the indicated entPhysicalIndex and
            entLogicalIndex pair.

            Since only physical ports are modeled in this table, only
            entries which represent interfaces or ports are allowed.  If
            an ifEntry exists on behalf of a particular physical port,
            then this object should identify the associated 'ifEntry'.
            For repeater ports, the appropriate row in the
            'rptrPortGroupTable' should be identified instead.

            For example, suppose a physical port was represented by
            entPhysicalEntry.3, entLogicalEntry.15 existed for a

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            repeater, and entLogicalEntry.22 existed for a bridge.  Then
            there might be two related instances of
            entAliasMappingIdentifier:
               entAliasMappingIdentifier.3.15 == rptrPortGroupIndex.5.2
               entAliasMappingIdentifier.3.22 == ifIndex.17
            It is possible that other mappings (besides interfaces and
            repeater ports) may be defined in the future, as required.

            Bridge ports are identified by examining the Bridge MIB and
            appropriate ifEntries associated with each 'dot1dBasePort',
            and are thus not represented in this table."
    ::= { entAliasMappingEntry 2 }

-- physical mapping table
entPhysicalContainsTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF EntPhysicalContainsEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A table which exposes the container/'containee'
            relationships between physical entities. This table provides
            all the information found by constructing the virtual
            containment tree for a given entPhysicalTable, but in a more
            direct format.

            In the event a physical entity is contained by more than one
            other physical entity (e.g., double-wide modules), this
            table should include these additional mappings, which cannot
            be represented in the entPhysicalTable virtual containment
            tree."
    ::= { entityMapping 3 }

entPhysicalContainsEntry OBJECT-TYPE
    SYNTAX      EntPhysicalContainsEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A single container/'containee' relationship."
    INDEX       { entPhysicalIndex, entPhysicalChildIndex }
    ::= { entPhysicalContainsTable 1 }

EntPhysicalContainsEntry ::= SEQUENCE {
      entPhysicalChildIndex     PhysicalIndex
}

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entPhysicalChildIndex OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of entPhysicalIndex for the contained physical
            entity."
    ::= { entPhysicalContainsEntry 1 }

-- last change time stamp for the whole MIB
entLastChangeTime OBJECT-TYPE
    SYNTAX      TimeStamp
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of sysUpTime at the time a conceptual row is
            created, modified, or deleted in any of these tables:
                    - entPhysicalTable
                    - entLogicalTable
                    - entLPMappingTable
                    - entAliasMappingTable
                    - entPhysicalContainsTable
            "
    ::= { entityGeneral 1 }

-- Entity MIB Trap Definitions
entityMIBTraps      OBJECT IDENTIFIER ::= { entityMIB 2 }
entityMIBTrapPrefix OBJECT IDENTIFIER ::= { entityMIBTraps 0 }

entConfigChange NOTIFICATION-TYPE
    STATUS             current
    DESCRIPTION
            "An entConfigChange notification is generated when the value
            of entLastChangeTime changes. It can be utilized by an NMS
            to trigger logical/physical entity table maintenance polls.

            An agent should not generate more than one entConfigChange
            'notification-event' in a given time interval (five seconds
            is the suggested default).  A 'notification-event' is the
            transmission of a single trap or inform PDU to a list of
            notification destinations.

            If additional configuration changes occur within the

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            throttling period, then notification-events for these
            changes should be suppressed by the agent until the current
            throttling period expires.  At the end of a throttling
            period, one notification-event should be generated if any
            configuration changes occurred since the start of the
            throttling period. In such a case, another throttling period
            is started right away.

            An NMS should periodically check the value of
            entLastChangeTime to detect any missed entConfigChange
            notification-events, e.g., due to throttling or transmission
            loss."
   ::= { entityMIBTrapPrefix 1 }

-- conformance information
entityConformance OBJECT IDENTIFIER ::= { entityMIB 3 }

entityCompliances OBJECT IDENTIFIER ::= { entityConformance 1 }
entityGroups      OBJECT IDENTIFIER ::= { entityConformance 2 }

-- compliance statements
entityCompliance MODULE-COMPLIANCE
    STATUS  deprecated
    DESCRIPTION
            "The compliance statement for SNMP entities which implement
            version 1 of the Entity MIB."
    MODULE  -- this module
        MANDATORY-GROUPS {
                           entityPhysicalGroup,
                           entityLogicalGroup,
                           entityMappingGroup,
                           entityGeneralGroup,
                           entityNotificationsGroup
        }
    ::= { entityCompliances 1 }

entity2Compliance MODULE-COMPLIANCE
    STATUS  current
    DESCRIPTION
            "The compliance statement for SNMP entities which implement
            version 2 of the Entity MIB."
    MODULE  -- this module
        MANDATORY-GROUPS {

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                           entityPhysicalGroup,
                           entityPhysical2Group,
                           entityGeneralGroup,
                           entityNotificationsGroup
        }
        GROUP entityLogical2Group
        DESCRIPTION
            "Implementation of this group is not mandatory for agents
            which model all MIB object instances within a single naming
            scope."

        GROUP entityMappingGroup
        DESCRIPTION
            "Implementation of the entPhysicalContainsTable is mandatory
            for all agents.  Implementation of the entLPMappingTable and
            entAliasMappingTables are not mandatory for agents which
            model all MIB object instances within a single naming scope.

            Note that the entAliasMappingTable may be useful for all
            agents, however implementation of the entityLogicalGroup or
            entityLogical2Group is required to support this table."

        OBJECT entPhysicalSerialNum
        MIN-ACCESS   not-accessible
        DESCRIPTION
            "Read and write access is not required for agents which
            cannot identify serial number information for physical
            entities, and/or cannot provide non-volatile storage for
            NMS-assigned serial numbers.

            Write access is not required for agents which can identify
            serial number information for physical entities, but cannot
            provide non-volatile storage for NMS-assigned serial
            numbers.

            Write access is not required for physical entities for
            physical entities for which the associated value of the
            entPhysicalIsFRU object is equal to 'false(2)'."

        OBJECT entPhysicalAlias
        MIN-ACCESS   read-only
        DESCRIPTION
            "Write access is required only if the associated
            entPhysicalClass value is equal to 'chassis(3)'."

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        OBJECT entPhysicalAssetID
        MIN-ACCESS   not-accessible
        DESCRIPTION
            "Read and write access is not required for agents which
            cannot provide non-volatile storage for NMS-assigned asset
            identifiers.

            Write access is not required for physical entities for which
            the associated value of entPhysicalIsFRU is equal to
            'false(2)'."
    ::= { entityCompliances 2 }

-- MIB groupings
entityPhysicalGroup    OBJECT-GROUP
    OBJECTS {
              entPhysicalDescr,
              entPhysicalVendorType,
              entPhysicalContainedIn,
              entPhysicalClass,
              entPhysicalParentRelPos,
              entPhysicalName
            }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent
            physical system components, for which a single agent
            provides management information."
    ::= { entityGroups 1 }

entityLogicalGroup    OBJECT-GROUP
    OBJECTS {
              entLogicalDescr,
              entLogicalType,
              entLogicalCommunity,
              entLogicalTAddress,
              entLogicalTDomain
            }
    STATUS  deprecated
    DESCRIPTION
            "The collection of objects which are used to represent the
            list of logical entities for which a single agent provides
            management information."
    ::= { entityGroups 2 }

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entityMappingGroup    OBJECT-GROUP
    OBJECTS {
              entLPPhysicalIndex,
              entAliasMappingIdentifier,
              entPhysicalChildIndex
            }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent the
            associations between multiple logical entities, physical
            components, interfaces, and port identifiers for which a
            single agent provides management information."
    ::= { entityGroups 3 }

entityGeneralGroup    OBJECT-GROUP
    OBJECTS {
              entLastChangeTime
            }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent
            general entity information for which a single agent provides
            management information."
    ::= { entityGroups 4 }

entityNotificationsGroup NOTIFICATION-GROUP
    NOTIFICATIONS { entConfigChange }
    STATUS        current
    DESCRIPTION
            "The collection of notifications used to indicate Entity MIB
            data consistency and general status information."
    ::= { entityGroups 5 }

entityPhysical2Group    OBJECT-GROUP
    OBJECTS {
              entPhysicalHardwareRev,
              entPhysicalFirmwareRev,
              entPhysicalSoftwareRev,
              entPhysicalSerialNum,
              entPhysicalMfgName,
              entPhysicalModelName,
              entPhysicalAlias,
              entPhysicalAssetID,
              entPhysicalIsFRU
            }

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    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent
            physical system components, for which a single agent
            provides management information.  This group augments the
            objects contained in the entityPhysicalGroup."
    ::= { entityGroups 6 }

entityLogical2Group    OBJECT-GROUP
    OBJECTS {
              entLogicalDescr,
              entLogicalType,
              entLogicalTAddress,
              entLogicalTDomain,
              entLogicalContextEngineID,
              entLogicalContextName
            }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent the
            list of logical entities for which a single SNMP entity
            provides management information."
    ::= { entityGroups 7 }

END

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7.  Usage Examples

The following sections iterate the instance values for two example
networking devices. These examples are kept simple to make them more
understandable. Auxiliary components, such as fans, sensors, empty
slots, and sub-modules are not shown, but might be modeled in real
implementations.

7.1.  Router/Bridge

A router containing two slots.  Each slot contains a 3 port
router/bridge module. Each port is represented in the ifTable.  There
are two logical instances of OSPF running and two logical bridges:

  Physical entities -- entPhysicalTable:
    1 Field-replaceable physical chassis:
      entPhysicalDescr.1 ==             'Acme Chassis Model 100'
      entPhysicalVendorType.1 ==        acmeProducts.chassisTypes.1
      entPhysicalContainedIn.1 ==       0
      entPhysicalClass.1 ==             chassis(3)
      entPhysicalParentRelPos.1 ==      0
      entPhysicalName.1 ==              '100-A'
      entPhysicalHardwareRev.1 ==       'A(1.00.02)'
      entPhysicalSoftwareRev.1 ==       ''
      entPhysicalFirmwareRev.1 ==       ''
      entPhysicalSerialNum.1 ==         'C100076544'
      entPhysicalMfgName.1 ==           'Acme'
      entPhysicalModelName.1 ==         '100'
      entPhysicalAlias.1 ==             'cl-SJ17-3-006:rack1:rtr-U3'
      entPhysicalAssetID.1 ==           '0007372293'
      entPhysicalIsFRU.1 ==             true(1)

    2 slots within the chassis:
      entPhysicalDescr.2 ==             'Acme Chassis Slot Type AA'
      entPhysicalVendorType.2  ==       acmeProducts.slotTypes.1
      entPhysicalContainedIn.2 ==       1
      entPhysicalClass.2 ==             container(5)
      entPhysicalParentRelPos.2 ==      1
      entPhysicalName.2 ==              'S1'
      entPhysicalHardwareRev.2 ==       'B(1.00.01)'
      entPhysicalSoftwareRev.2 ==       ''
      entPhysicalFirmwareRev.2 ==       ''
      entPhysicalSerialNum.2 ==         ''
      entPhysicalMfgName.2 ==           'Acme'

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      entPhysicalModelName.2 ==         'AA'
      entPhysicalAlias.2 ==             ''
      entPhysicalAssetID.2 ==           ''
      entPhysicalIsFRU.2 ==             false(2)

      entPhysicalDescr.3 ==             'Acme Chassis Slot Type AA'
      entPhysicalVendorType.3 =         acmeProducts.slotTypes.1
      entPhysicalContainedIn.3 ==       1
      entPhysicalClass.3 ==             container(5)
      entPhysicalParentRelPos.3 ==      2
      entPhysicalName.3 ==              'S2'
      entPhysicalHardwareRev.3 ==       '1.00.07'
      entPhysicalSoftwareRev.3 ==       ''
      entPhysicalFirmwareRev.3 ==       ''
      entPhysicalSerialNum.3 ==         ''
      entPhysicalMfgName.3 ==           'Acme'
      entPhysicalModelName.3 ==         'AA'
      entPhysicalAlias.3 ==             ''
      entPhysicalAssetID.3 ==           ''
      entPhysicalIsFRU.3 ==             false(2)

    2 Field-replaceable modules:
    Slot 1 contains a module with 3 ports:
      entPhysicalDescr.4 ==             'Acme Router-100'
      entPhysicalVendorType.4  ==       acmeProducts.moduleTypes.14
      entPhysicalContainedIn.4 ==       2
      entPhysicalClass.4 ==             module(9)
      entPhysicalParentRelPos.4 ==      1
      entPhysicalName.4 ==              'M1'
      entPhysicalHardwareRev.4 ==       '1.00.07'
      entPhysicalSoftwareRev.4 ==       '1.4.1'
      entPhysicalFirmwareRev.4 ==       'A(1.1)'
      entPhysicalSerialNum.4 ==         'C100087363'
      entPhysicalMfgName.4 ==           'Acme'
      entPhysicalModelName.4 ==         'R100-FE'
      entPhysicalAlias.4 ==             'rtr-U3:m1:SJ17-3-eng'
      entPhysicalAssetID.4 ==           '0007372462'
      entPhysicalIsFRU.4 ==             true(1)

      entPhysicalDescr.5 ==             'Acme Ethernet-100 Port'
      entPhysicalVendorType.5  ==       acmeProducts.portTypes.2
      entPhysicalContainedIn.5 ==       4
      entPhysicalClass.5 ==             port(10)
      entPhysicalParentRelPos.5 ==      1
      entPhysicalName.5 ==              'P1'

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      entPhysicalHardwareRev.5 ==       'G(1.02)'
      entPhysicalSoftwareRev.5 ==       ''
      entPhysicalFirmwareRev.5 ==       '1.1'
      entPhysicalSerialNum.5 ==         ''
      entPhysicalMfgName.5 ==           'Acme'
      entPhysicalModelName.5 ==         'FE-100'
      entPhysicalAlias.5 ==             ''
      entPhysicalAssetID.5 ==           ''
      entPhysicalIsFRU.5 ==             false(2)

      entPhysicalDescr.6 ==             'Acme Ethernet-100 Port'
      entPhysicalVendorType.6  ==       acmeProducts.portTypes.2
      entPhysicalContainedIn.6 ==       4
      entPhysicalClass.6 ==             port(10)
      entPhysicalParentRelPos.6 ==      2
      entPhysicalName.6 ==              'P2'
      entPhysicalHardwareRev.6 ==       'G(1.02)'
      entPhysicalSoftwareRev.6 ==       ''
      entPhysicalFirmwareRev.6 ==       '1.1'
      entPhysicalSerialNum.6 ==         ''
      entPhysicalMfgName.6 ==           'Acme'
      entPhysicalModelName.6 ==         'FE-100'
      entPhysicalAlias.6 ==             ''
      entPhysicalAssetID.6 ==           ''
      entPhysicalIsFRU.6 ==             false(2)

      entPhysicalDescr.7 ==             'Acme Router-100 FDDI-Port'
      entPhysicalVendorType.7  ==       acmeProducts.portTypes.3
      entPhysicalContainedIn.7 ==       4
      entPhysicalClass.7 ==             port(10)
      entPhysicalParentRelPos.7 ==      3
      entPhysicalName.7 ==              'P3'
      entPhysicalHardwareRev.7 ==       'B(1.03)'
      entPhysicalSoftwareRev.7 ==       '2.5.1'
      entPhysicalFirmwareRev.7 ==       '2.5F'
      entPhysicalSerialNum.7 ==         ''
      entPhysicalMfgName.7 ==           'Acme'
      entPhysicalModelName.7 ==         'FDDI-100'
      entPhysicalAlias.7 ==             ''
      entPhysicalAssetID.7 ==           ''
      entPhysicalIsFRU.7 ==             false(2)

   Slot 2 contains another 3-port module:
      entPhysicalDescr.8 ==             'Acme Router-100 Comm Module'
      entPhysicalVendorType.8  ==       acmeProducts.moduleTypes.15

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      entPhysicalContainedIn.8 ==       3
      entPhysicalClass.8 ==             module(9)
      entPhysicalParentRelPos.8 ==      1
      entPhysicalName.8 ==              'M2'
      entPhysicalHardwareRev.8 ==       '2.01.00'
      entPhysicalSoftwareRev.8 ==       '3.0.7'
      entPhysicalFirmwareRev.8 ==       'A(1.2)'
      entPhysicalSerialNum.8 ==         'C100098732'
      entPhysicalMfgName.8 ==           'Acme'
      entPhysicalModelName.8 ==         'C100'
      entPhysicalAlias.8 ==             'rtr-U3:m2:SJ17-2-eng'
      entPhysicalAssetID.8 ==           '0007373982'
      entPhysicalIsFRU.8 ==             true(1)

      entPhysicalDescr.9 ==             'Acme Fddi-100 Port'
      entPhysicalVendorType.9 ==        acmeProducts.portTypes.5
      entPhysicalContainedIn.9 ==       8
      entPhysicalClass.9 ==             port(10)
      entPhysicalParentRelPos.9 ==      1
      entPhysicalName.9 ==              'FDDI Primary'
      entPhysicalHardwareRev.9 ==       'CC(1.07)'
      entPhysicalSoftwareRev.9 ==       '2.0.34'
      entPhysicalFirmwareRev.9 ==       '1.1'
      entPhysicalSerialNum.9 ==         ''
      entPhysicalMfgName.9 ==           'Acme'
      entPhysicalModelName.9 ==         'FDDI-100'
      entPhysicalAlias.9 ==             ''
      entPhysicalAssetID.9 ==           ''
      entPhysicalIsFRU.9 ==             false(2)

      entPhysicalDescr.10 ==            'Acme Ethernet-100 Port'
      entPhysicalVendorType.10 ==       acmeProducts.portTypes.2
      entPhysicalContainedIn.10 ==      8
      entPhysicalClass.10 ==            port(10)
      entPhysicalParentRelPos.10 ==     2
      entPhysicalName.10 ==             'Ethernet A'
      entPhysicalHardwareRev.10 ==      'G(1.04)'
      entPhysicalSoftwareRev.10 ==      ''
      entPhysicalFirmwareRev.10 ==      '1.3'
      entPhysicalSerialNum.10 ==        ''
      entPhysicalMfgName.10 ==          'Acme'
      entPhysicalModelName.10 ==        'FE-100'
      entPhysicalAlias.10 ==            ''
      entPhysicalAssetID.10 ==          ''
      entPhysicalIsFRU.10 ==            false(2)

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      entPhysicalDescr.11 ==            'Acme Ethernet-100 Port'
      entPhysicalVendorType.11 ==       acmeProducts.portTypes.2
      entPhysicalContainedIn.11 ==      8
      entPhysicalClass.11 ==            port(10)
      entPhysicalParentRelPos.11 ==     3
      entPhysicalName.11 ==             'Ethernet B'
      entPhysicalHardwareRev.11 ==      'G(1.04)'
      entPhysicalSoftwareRev.11 ==      ''
      entPhysicalFirmwareRev.11 ==      '1.3'
      entPhysicalSerialNum.11 ==        ''
      entPhysicalMfgName.11 ==          'Acme'
      entPhysicalModelName.11 ==        'FE-100'
      entPhysicalAlias.11 ==            ''
      entPhysicalAssetID.11 ==          ''
      entPhysicalIsFRU.11 ==            false(2)

   Logical entities -- entLogicalTable; no SNMPv3 support
    2 OSPF instances:
      entLogicalDescr.1 ==              'Acme OSPF v1.1'
      entLogicalType.1 ==               ospf
      entLogicalCommunity.1 ==          'public-ospf1'
      entLogicalTAddress.1 ==           124.125.126.127:161
      entLogicalTDomain.1 ==            snmpUDPDomain
      entLogicalContextEngineID.1 ==    ''
      entLogicalContextName.1 ==        ''

      entLogicalDescr.2 ==              'Acme OSPF v1.1'
      entLogicalType.2 ==               ospf
      entLogicalCommunity.2 ==          'public-ospf2'
      entLogicalTAddress.2 ==           124.125.126.127:161
      entLogicalTDomain.2 ==            snmpUDPDomain
      entLogicalContextEngineID.2 ==    ''
      entLogicalContextName.2 ==        ''

    2 logical bridges:
      entLogicalDescr.3 ==              'Acme Bridge v2.1.1'
      entLogicalType.3  ==              dot1dBridge
      entLogicalCommunity.3 ==          'public-bridge1'
      entLogicalTAddress.3 ==           124.125.126.127:161
      entLogicalTDomain.3 ==            snmpUDPDomain
      entLogicalContextEngineID.3 ==    ''
      entLogicalContextName.3 ==        ''

      entLogicalDescr.4 ==              'Acme Bridge v2.1.1'
      entLogicalType.4 ==               dot1dBridge

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      entLogicalCommunity.4 ==          'public-bridge2'
      entLogicalTAddress.4 ==           124.125.126.127:161
      entLogicalTDomain.4 ==            snmpUDPDomain
      entLogicalContextEngineID.4 ==    ''
      entLogicalContextName.4 ==        ''

Logical to Physical Mappings:
  1st OSPF instance: uses module 1-port 1
      entLPPhysicalIndex.1.5 ==         5

  2nd OSPF instance: uses module 2-port 1
      entLPPhysicalIndex.2.9 ==         9

  1st bridge group: uses module 1, all ports

  [ed. -- Note that these mappings are included in the table since
  another logical entity (1st OSPF) utilizes one of the
  ports. If this were not the case, then a single mapping
  to the module (e.g., entLPPhysicalIndex.3.4) would be
  present instead. ]
      entLPPhysicalIndex.3.5 ==         5
      entLPPhysicalIndex.3.6 ==         6
      entLPPhysicalIndex.3.7 ==         7

  2nd bridge group: uses module 2, all ports
      entLPPhysicalIndex.4.9  ==        9
      entLPPhysicalIndex.4.10 ==        10
      entLPPhysicalIndex.4.11 ==        11

Physical to Logical to MIB Alias Mappings -- entAliasMappingTable:
  Example 1: ifIndex values are global to all logical entities
      entAliasMappingIdentifier.5.0 ==  ifIndex.1
      entAliasMappingIdentifier.6.0 ==  ifIndex.2
      entAliasMappingIdentifier.7.0 ==  ifIndex.3
      entAliasMappingIdentifier.9.0 ==  ifIndex.4
      entAliasMappingIdentifier.10.0 == ifIndex.5
      entAliasMappingIdentifier.11.0 == ifIndex.6

  Example 2: ifIndex values are not shared by all logical entities
      entAliasMappingIdentifier.5.0 ==  ifIndex.1
      entAliasMappingIdentifier.5.3 ==  ifIndex.101
      entAliasMappingIdentifier.6.0 ==  ifIndex.2
      entAliasMappingIdentifier.6.3 ==  ifIndex.102
      entAliasMappingIdentifier.7.0 ==  ifIndex.3
      entAliasMappingIdentifier.7.3 ==  ifIndex.103

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      entAliasMappingIdentifier.9.0 ==  ifIndex.4
      entAliasMappingIdentifier.9.3 ==  ifIndex.204
      entAliasMappingIdentifier.10.0 == ifIndex.5
      entAliasMappingIdentifier.10.3 == ifIndex.205
      entAliasMappingIdentifier.11.0 == ifIndex.6
      entAliasMappingIdentifier.11.3 == ifIndex.206

Physical Containment Tree -- entPhysicalContainsTable
  chassis has two containers:
      entPhysicalChildIndex.1.2 ==      2
      entPhysicalChildIndex.1.3 ==      3

  container 1 has a module:
      entPhysicalChildIndex.2.4 ==      4

  container 2 has a module:
      entPhysicalChildIndex.3.8 ==      8

  module 1 has 3 ports:
      entPhysicalChildIndex.4.5 ==      5
      entPhysicalChildIndex.4.6 ==      6
      entPhysicalChildIndex.4.7 ==      7

  module 2 has 3 ports:
      entPhysicalChildIndex.8.9 ==      9
      entPhysicalChildIndex.8.10 ==     10
      entPhysicalChildIndex.1.11 ==     11

7.2.  Repeaters

A 3-slot Hub with 2 backplane ethernet segments.  Slot three is empty,
and the remaining slots contain ethernet repeater modules.

Note that this example assumes an older Repeater MIB implementation,
(RFC 1516 [RFC1516]) rather than the new Repeater MIB (RFC 2108
[RFC2108]).  The new version contains an object called 'rptrPortRptrId',
which should be used to identify repeater port groupings, rather than
with community strings or contexts.

Physical entities -- entPhysicalTable:
   1 Field-replaceable physical chassis:
      entPhysicalDescr.1 ==          'Acme Chassis Model 110'
      entPhysicalVendorType.1 ==     acmeProducts.chassisTypes.2
      entPhysicalContainedIn.1 ==    0

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      entPhysicalClass.1 ==          chassis(3)
      entPhysicalParentRelPos.1 ==   0
      entPhysicalName.1 ==           '110-B'
      entPhysicalHardwareRev.1 ==    'A(1.02.00)'
      entPhysicalSoftwareRev.1 ==    ''
      entPhysicalFirmwareRev.1 ==    ''
      entPhysicalSerialNum.1 ==      'C100079294'
      entPhysicalMfgName.1 ==        'Acme'
      entPhysicalModelName.1 ==      '110'
      entPhysicalAlias.1 ==          'bldg09:floor1:rptr18:0067eea0229f'
      entPhysicalAssetID.1 ==        '0007386327'
      entPhysicalIsFRU.1 ==          true(1)

   2 Chassis Ethernet Backplanes:
      entPhysicalDescr.2 ==          'Acme Ethernet Backplane Type A'
      entPhysicalVendorType.2 ==     acmeProducts.backplaneTypes.1
      entPhysicalContainedIn.2 ==    1
      entPhysicalClass.2 ==          backplane(4)
      entPhysicalParentRelPos.2 ==   1
      entPhysicalName.2 ==           'B1'
      entPhysicalHardwareRev.2 ==    'A(2.04.01)'
      entPhysicalSoftwareRev.2 ==    ''
      entPhysicalFirmwareRev.2 ==    ''
      entPhysicalSerialNum.2 ==      ''
      entPhysicalMfgName.2 ==        'Acme'
      entPhysicalModelName.2 ==      'BK-A'
      entPhysicalAlias.2 ==          ''
      entPhysicalAssetID.2 ==        ''
      entPhysicalIsFRU.2 ==          false(2)

      entPhysicalDescr.3 ==          'Acme Ethernet Backplane Type A'
      entPhysicalVendorType.3  ==    acmeProducts.backplaneTypes.1
      entPhysicalContainedIn.3 ==    1
      entPhysicalClass.3 ==          backplane(4)
      entPhysicalParentRelPos.3 ==   2
      entPhysicalName.3 ==           'B2'
      entPhysicalHardwareRev.3 ==    'A(2.04.01)'
      entPhysicalSoftwareRev.3 ==    ''
      entPhysicalFirmwareRev.3 ==    ''
      entPhysicalSerialNum.3 ==      ''
      entPhysicalMfgName.3 ==        'Acme'
      entPhysicalModelName.3 ==      'BK-A'
      entPhysicalAlias.3 ==          ''
      entPhysicalAssetID.3 ==        ''
      entPhysicalIsFRU.3 ==          false(2)

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   3 slots within the chassis:
      entPhysicalDescr.4 ==          'Acme Hub Slot Type RB'
      entPhysicalVendorType.4  ==    acmeProducts.slotTypes.5
      entPhysicalContainedIn.4 ==    1
      entPhysicalClass.4 ==          container(5)
      entPhysicalParentRelPos.4 ==   1
      entPhysicalName.4 ==           'Slot 1'
      entPhysicalHardwareRev.4 ==    'B(1.00.03)'
      entPhysicalSoftwareRev.4 ==    ''
      entPhysicalFirmwareRev.4 ==    ''
      entPhysicalSerialNum.4 ==      ''
      entPhysicalMfgName.4 ==        'Acme'
      entPhysicalModelName.4 ==      'RB'
      entPhysicalAlias.4 ==          ''
      entPhysicalAssetID.4 ==        ''
      entPhysicalIsFRU.4 ==          false(2)

      entPhysicalDescr.5 ==          'Acme Hub Slot Type RB'
      entPhysicalVendorType.5  ==    acmeProducts.slotTypes.5
      entPhysicalContainedIn.5 ==    1
      entPhysicalClass.5 ==          container(5)
      entPhysicalParentRelPos.5 ==   2
      entPhysicalName.5 ==           'Slot 2'
      entPhysicalHardwareRev.5 ==    'B(1.00.03)'
      entPhysicalSoftwareRev.5 ==    ''
      entPhysicalFirmwareRev.5 ==    ''
      entPhysicalSerialNum.5 ==      ''
      entPhysicalMfgName.5 ==        'Acme'
      entPhysicalModelName.5 ==      'RB'
      entPhysicalAlias.5 ==          ''
      entPhysicalAssetID.5 ==        ''
      entPhysicalIsFRU.5 ==          false(2)

      entPhysicalDescr.6 ==          'Acme Hub Slot Type RB'
      entPhysicalVendorType.6  ==    acmeProducts.slotTypes.5
      entPhysicalContainedIn.6 ==    1
      entPhysicalClass.6 ==          container(5)
      entPhysicalParentRelPos.6 ==   3
      entPhysicalName.6 ==           'Slot 3'
      entPhysicalHardwareRev.6 ==    'B(1.00.03)'
      entPhysicalSoftwareRev.6 ==    ''
      entPhysicalFirmwareRev.6 ==    ''
      entPhysicalSerialNum.6 ==      ''
      entPhysicalMfgName.6 ==        'Acme'
      entPhysicalModelName.6 ==      'RB'

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      entPhysicalAlias.6 ==          ''
      entPhysicalAssetID.6 ==        ''
      entPhysicalIsFRU.6 ==          false(2)

   Slot 1 contains a plug-in module with 4 10-BaseT ports:
      entPhysicalDescr.7  ==         'Acme 10Base-T Module 114'
      entPhysicalVendorType.7 ==     acmeProducts.moduleTypes.32
      entPhysicalContainedIn.7  ==   4
      entPhysicalClass.7 ==          module(9)
      entPhysicalParentRelPos.7 ==   1
      entPhysicalName.7 ==           'M1'
      entPhysicalHardwareRev.7 ==    'A(1.02.01)'
      entPhysicalSoftwareRev.7 ==    '1.7.2'
      entPhysicalFirmwareRev.7 ==    'A(1.5)'
      entPhysicalSerialNum.7 ==      'C100096244'
      entPhysicalMfgName.7 ==        'Acme'
      entPhysicalModelName.7 =       '114'
      entPhysicalAlias.7 ==          'bldg09:floor1:eng'
      entPhysicalAssetID.7 ==        '0007962951'
      entPhysicalIsFRU.7 ==          true(1)

      entPhysicalDescr.8 ==          'Acme 10Base-T Port RB'
      entPhysicalVendorType.8 ==     acmeProducts.portTypes.10
      entPhysicalContainedIn.8  ==   7
      entPhysicalClass.8 ==          port(10)
      entPhysicalParentRelPos.8 ==   1
      entPhysicalName.8 ==           'Ethernet-A'
      entPhysicalHardwareRev.8 ==    'A(1.04F)'
      entPhysicalSoftwareRev.8 ==    ''
      entPhysicalFirmwareRev.8 ==    '1.4'
      entPhysicalSerialNum.8 ==      ''
      entPhysicalMfgName.8 ==        'Acme'
      entPhysicalModelName.8 ==      'RB'
      entPhysicalAlias.8 ==          ''
      entPhysicalAssetID.8 ==        ''
      entPhysicalIsFRU.8 ==          false(2)

      entPhysicalDescr.9  ==         'Acme 10Base-T Port RB'
      entPhysicalVendorType.9 ==     acmeProducts.portTypes.10
      entPhysicalContainedIn.9 ==    7
      entPhysicalClass.9 ==          port(10)
      entPhysicalParentRelPos.9 ==   2
      entPhysicalName.9 ==           'Ethernet-B'
      entPhysicalHardwareRev.9 ==    'A(1.04F)'
      entPhysicalSoftwareRev.9 ==    ''

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      entPhysicalFirmwareRev.9 ==    '1.4'
      entPhysicalSerialNum.9 ==      ''
      entPhysicalMfgName.9 ==        'Acme'
      entPhysicalModelName.9 =       'RB'
      entPhysicalAlias.9 ==          ''
      entPhysicalAssetID.9 ==        ''
      entPhysicalIsFRU.9 ==          false(2)

      entPhysicalDescr.10 ==         'Acme 10Base-T Port RB'
      entPhysicalVendorType.10 ==    acmeProducts.portTypes.10
      entPhysicalContainedIn.10 ==   7
      entPhysicalClass.10 ==         port(10)
      entPhysicalParentRelPos.10 ==  3
      entPhysicalName.10 ==          'Ethernet-C'
      entPhysicalHardwareRev.10 ==   'B(1.02.07)'
      entPhysicalSoftwareRev.10 ==   ''
      entPhysicalFirmwareRev.10 ==   '1.4'
      entPhysicalSerialNum.10 ==     ''
      entPhysicalMfgName.10 ==       'Acme'
      entPhysicalModelName.10 ==     'RB'
      entPhysicalAlias.10 ==         ''
      entPhysicalAssetID.10 ==       ''
      entPhysicalIsFRU.10 ==         false(2)

      entPhysicalDescr.11 ==         'Acme 10Base-T Port RB'
      entPhysicalVendorType.11  ==   acmeProducts.portTypes.10
      entPhysicalContainedIn.11 ==   7
      entPhysicalClass.11 ==         port(10)
      entPhysicalParentRelPos.11 ==  4
      entPhysicalName.11 ==          'Ethernet-D'
      entPhysicalHardwareRev.11 ==   'B(1.02.07)'
      entPhysicalSoftwareRev.11 ==   ''
      entPhysicalFirmwareRev.11 ==   '1.4'
      entPhysicalSerialNum.11 ==     ''
      entPhysicalMfgName.11 ==       'Acme'
      entPhysicalModelName.11 ==     'RB'
      entPhysicalAlias.11 ==         ''
      entPhysicalAssetID.11 ==       ''
      entPhysicalIsFRU.11 ==         false(2)

   Slot 2 contains another ethernet module with 2 ports.
      entPhysicalDescr.12 ==         'Acme 10Base-T Module Model 4'
      entPhysicalVendorType.12 ==    acmeProducts.moduleTypes.30
      entPhysicalContainedIn.12 =    5
      entPhysicalClass.12 ==         module(9)

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      entPhysicalParentRelPos.12 ==  1
      entPhysicalName.12 ==          'M2'
      entPhysicalHardwareRev.12 ==   'A(1.01.07)'
      entPhysicalSoftwareRev.12 ==   '1.8.4'
      entPhysicalFirmwareRev.12 ==   'A(1.8)'
      entPhysicalSerialNum.12 ==     'C100102384'
      entPhysicalMfgName.12 ==       'Acme'
      entPhysicalModelName.12 ==     '4'
      entPhysicalAlias.12 ==         'bldg09:floor1:devtest'
      entPhysicalAssetID.12 ==       '0007968462'
      entPhysicalIsFRU.12 ==         true(1)

      entPhysicalDescr.13 ==         'Acme 802.3 AUI Port'
      entPhysicalVendorType.13  ==   acmeProducts.portTypes.11
      entPhysicalContainedIn.13 ==   12
      entPhysicalClass.13 ==         port(10)
      entPhysicalParentRelPos.13 ==  1
      entPhysicalName.13 ==          'AUI'
      entPhysicalHardwareRev.13 ==   'A(1.06F)'
      entPhysicalSoftwareRev.13 ==   ''
      entPhysicalFirmwareRev.13 ==   '1.5'
      entPhysicalSerialNum.13 ==     ''
      entPhysicalMfgName.13 ==       'Acme'
      entPhysicalModelName.13 ==     ''
      entPhysicalAlias.13 ==         ''
      entPhysicalAssetID.13 ==       ''
      entPhysicalIsFRU.13 ==         false(2)

      entPhysicalDescr.14 ==         'Acme 10Base-T Port RD'
      entPhysicalVendorType.14  ==   acmeProducts.portTypes.14
      entPhysicalContainedIn.14 ==   12
      entPhysicalClass.14 ==         port(10)
      entPhysicalParentRelPos.14 ==  2
      entPhysicalName.14 ==          'E2'
      entPhysicalHardwareRev.14 ==   'B(1.01.02)'
      entPhysicalSoftwareRev.14 ==   ''
      entPhysicalFirmwareRev.14 ==   '2.1'
      entPhysicalSerialNum.14 ==     ''
      entPhysicalMfgName.14 ==       'Acme'
      entPhysicalModelName.14 ==     ''
      entPhysicalAlias.14 ==         ''
      entPhysicalAssetID.14 ==       ''
      entPhysicalIsFRU.14 ==         false(2)

Logical entities -- entLogicalTable; with SNMPv3 support

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   Repeater 1--comprised of any ports attached to backplane 1
      entLogicalDescr.1 ==           'Acme repeater v3.1'
      entLogicalType.1  ==           snmpDot3RptrMgt
      entLogicalCommunity.1          'public-repeater1'
      entLogicalTAddress.1 ==        124.125.126.127:161
      entLogicalTDomain.1 ==         snmpUDPDomain
      entLogicalContextEngineID.1 == '80000777017c7d7e7f'H
      entLogicalContextName.1 ==     'repeater1'

   Repeater 2--comprised of any ports attached to backplane 2:
      entLogicalDescr.2 ==           'Acme repeater v3.1'
      entLogicalType.2  ==           snmpDot3RptrMgt
      entLogicalCommunity.2 ==       'public-repeater2'
      entLogicalTAddress.2 ==        124.125.126.127:161
      entLogicalTDomain.2 ==         snmpUDPDomain
      entLogicalContextEngineID.2 == '80000777017c7d7e7f'H
      entLogicalContextName.2 ==     'repeater2'

Logical to Physical Mappings -- entLPMappingTable:

  repeater1 uses backplane 1, slot 1-ports 1 & 2, slot 2-port 1
  [ed. -- Note that a mapping to the module is not included,
   since in this example represents a port-switchable hub.
   Even though all ports on the module could belong to the
   same repeater as a matter of configuration, the LP port
   mappings should not be replaced dynamically with a single
   mapping for the module (e.g., entLPPhysicalIndex.1.7).
   If all ports on the module shared a single backplane connection,
   then a single mapping for the module would be more appropriate. ]

     entLPPhysicalIndex.1.2 ==       2
     entLPPhysicalIndex.1.8 ==       8
     entLPPhysicalIndex.1.9 ==       9
     entLPPhysicalIndex.1.13 ==      13

  repeater2 uses backplane 2, slot 1-ports 3 & 4, slot 2-port 2
      entLPPhysicalIndex.2.3 ==      3
      entLPPhysicalIndex.2.10 ==     10
      entLPPhysicalIndex.2.11 ==     11
      entLPPhysicalIndex.2.14 ==     14

Physical to Logical to MIB Alias Mappings -- entAliasMappingTable:
  Repeater Port Identifier values are shared by both repeaters:
      entAliasMappingIdentifier.8.0 ==      rptrPortGroupIndex.1.1
      entAliasMappingIdentifier.9.0 ==      rptrPortGroupIndex.1.2

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      entAliasMappingIdentifier.10.0 ==     rptrPortGroupIndex.1.3
      entAliasMappingIdentifier.11.0 ==     rptrPortGroupIndex.1.4
      entAliasMappingIdentifier.13.0 ==     rptrPortGroupIndex.2.1
      entAliasMappingIdentifier.14.0 ==     rptrPortGroupIndex.2.2

Physical Containment Tree -- entPhysicalContainsTable
  chassis has two backplanes and three containers:
      entPhysicalChildIndex.1.2 ==   2
      entPhysicalChildIndex.1.3 ==   3
      entPhysicalChildIndex.1.4 ==   4
      entPhysicalChildIndex.1.5 ==   5
      entPhysicalChildIndex.1.6 ==   6

  container 1 has a module:
      entPhysicalChildIndex.4.7 ==   7

  container 2 has a module
      entPhysicalChildIndex.5.12 ==  12
  [ed. - in this example, container 3 is empty.]

  module 1 has 4 ports:
      entPhysicalChildIndex.7.8 ==   8
      entPhysicalChildIndex.7.9 ==   9
      entPhysicalChildIndex.7.10 ==  10
      entPhysicalChildIndex.7.11 ==  11

  module 2 has 2 ports:
      entPhysicalChildIndex.12.13 == 13
      entPhysicalChildIndex.12.14 == 14

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8.  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.

9.  Acknowledgements

This memo has been produced by the IETF's Entity MIB working group.

10.  References

[RFC1155]
     Rose, M., and K. McCloghrie, "Structure and Identification of
     Management Information for TCP/IP-based Internets", RFC 1155, STD
     16, Performance Systems International, Hughes LAN Systems, May
     1990.

[RFC1157]
     Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network
     Management Protocol", RFC 1157, STD 15, SNMP Research, Performance
     Systems International, Performance Systems International, MIT
     Laboratory for Computer Science, May 1990.

[RFC1212]
     Rose, M., and K. McCloghrie, "Concise MIB Definitions", RFC 1212,
     STD 16, Performance Systems International, Hughes LAN Systems,

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     March 1991.

[RFC1215]
     M. Rose, "A Convention for Defining Traps for use with the SNMP",
     RFC 1215, Performance Systems International, March 1991.

[RFC1493]
     Decker, E., Langille, P., Rijsinghani, A., and K. McCloghrie,
     "Definitions of Managed Objects for Bridges", RFC 1493, cisco
     Systems, Digital Equipment Corporation, Hughes LAN Systems, Inc.,
     July, 1993.

[RFC1516]
     McMaster, D., and K. McCloghrie, "Definitions of Managed Objects
     for IEEE 802.3 Repeater Devices", RFC 1516, SynOptics
     Communications, Inc., Hughes LAN Systems, Inc., September, 1993.

[RFC1901]
     Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
     "Introduction to Community-based SNMPv2", RFC 1901, SNMP Research,
     Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc.,
     International Network Services, January 1996.

[RFC1905]
     Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol
     Operations for Version 2 of the Simple Network Management Protocol
     (SNMPv2)", RFC 1905, SNMP Research, Inc., Cisco Systems, Inc.,
     Dover Beach Consulting, Inc., International Network Services,
     January 1996.

[RFC1906]
     Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Transport
     Mappings for Version 2 of the Simple Network Management Protocol
     (SNMPv2)", RFC 1906, SNMP Research, Inc., Cisco Systems, Inc.,
     Dover Beach Consulting, Inc., International Network Services,
     January 1996.

[RFC2026]
     Bradner, S., "The Internet Standards Process -- Revision 3", RFC
     2026, Harvard University, October, 1996.

[RFC2037]
     McCloghrie, K., and A. Bierman, "Entity MIB using SMIv2", RFC 2037,
     Cisco Systems, October 1996.

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[RFC2108]
     de Graaf, K., Romascanu, D., McMaster, D., and K. McCloghrie,
     "Definitions of Managed Objects for IEEE 802.3 Repeater Devices
     using SMIv2", RFC 2108, 3Com Corporation, Madge Networks (Israel)
     Ltd., Coloma Communications, Cisco Systems Inc., February, 1997.

[RFC2233]
     McCloghrie, K., and F. Kastenholz, "The Interfaces Group MIB Using
     SMIv2", RFC 2233, Cisco Systems, FTP Software, November, 1997.

[RFC2570]
     Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction to
     Version 3 of the Internet-standard Network Management Framework",
     RFC 2570, SNMP Research, Inc., TIS Labs at Network Associates,
     Inc., Ericsson, Cisco Systems, April 1999.

[RFC2571]
     Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for
     Describing SNMP Management Frameworks", RFC 2571, Cabletron
     Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, April
     1999.

[RFC2572]
     Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message
     Processing and Dispatching for the Simple Network Management
     Protocol (SNMP)", RFC 2572, SNMP Research, Inc., Cabletron Systems,
     Inc., BMC Software, Inc., IBM T. J. Watson Research, April 1999.

[RFC2573]
     Levi, D., Meyer, P., and B. Stewart, "SNMPv3 Applications", RFC
     2573, SNMP Research, Inc., Secure Computing Corporation, Cisco
     Systems, April 1999.

[RFC2574]
     Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for
     version 3 of the Simple Network Management Protocol (SNMPv3)", RFC
     2574, IBM T. J. Watson Research, April 1999.

[RFC2575]
     Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access
     Control Model (VACM) for the Simple Network Management Protocol
     (SNMP)", RFC 2575, IBM T. J. Watson Research, BMC Software, Inc.,
     Cisco Systems, Inc., April 1999.

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[RFC2578]
     McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.,
     and S. Waldbusser, "Structure of Management Information Version 2
     (SMIv2)", RFC 2578, STD 58, Cisco Systems, SNMPinfo, TU
     Braunschweig, SNMP Research, First Virtual Holdings, International
     Network Services, April 1999.

[RFC2579]
     McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.,
     and S. Waldbusser, "Textual Conventions for SMIv2", RFC 2579, STD
     58, Cisco Systems, SNMPinfo, TU Braunschweig, SNMP Research, First
     Virtual Holdings, International Network Services, April 1999.

[RFC2580]
     McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.,
     and S. Waldbusser, "Conformance Statements for SMIv2", RFC 2580,
     STD 58, Cisco Systems, SNMPinfo, TU Braunschweig, SNMP Research,
     First Virtual Holdings, International Network Services, April 1999.

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11.  Security Considerations

There are a number of management objects defined in this MIB that have a
MAX-ACCESS clause of read-write and/or read-create.  Such objects may be
considered sensitive or vulnerable in some network environments.  The
support for SET operations in a non-secure environment without proper
protection can have a negative effect on network operations.

There are a number of managed objects in this MIB that may contain
sensitive information. These are:

   entPhysicalDescr
   entPhysicalVendorType
   entPhysicalHardwareRev
   entPhysicalFirmwareRev
   entPhysicalSoftwareRev
   entPhysicalSerialNum
   entPhysicalMfgName
   entPhysicalModelName

These objects expose information about the physical entities within a
managed system, which may be used to identify the vendor, model, and
version information of each system component.

   entPhysicalAssetID

This object can allow asset identifiers for various system components to
be exposed, in the event this MIB object is actually configured by an
NMS application.

   entLogicalDescr
   entLogicalType

These objects expose the type of logical entities present in the managed
system.

   entLogicalCommunity

This object exposes community names associated with particular logical
entites within the system.

   entLogicalTAddress
   entLogicalTDomain

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These objects expose network addresses that can be used to communicate
with an SNMP agent on behalf of particular logical entities within the
system.

   entLogicalContextEngineID
   entLogicalContextName

These objects identify the authoritative SNMP engine that contains
information on behalf of particular logical entities within the system.

It is thus important to control even GET access to these objects and
possibly to even encrypt the values of these object when sending them
over the network via SNMP.  Not all versions of SNMP provide features
for such a secure environment.

SNMPv1 by itself is not a secure environment.  Even if the network
itself is secure (for example by using IPSec), even then, 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 implementers consider the security features
as provided by the SNMPv3 framework.  Specifically, the use of the User-
based Security Model RFC 2574 [RFC2574] and the View-based Access
Control Model RFC 2575 [RFC2575] 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 the objects only to those principals (users) that have
legitimate rights to indeed GET or SET (change/create/delete) them.

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12.  Authors' Addresses

     Keith McCloghrie
     Cisco Systems, Inc.
     170 West Tasman Drive
     San Jose, CA 95134 USA
     Phone: +1 408-526-5260
     Email: kzm@cisco.com

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

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13.  Full Copyright Statement

Copyright (C) The Internet Society (1999).  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 copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE."

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