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rfc:rfc2037

Network Working Group K. McCloghrie Request for Comments: 2037 A. Bierman Category: Standards Track Cisco Systems

                                                         October 1996
                       Entity MIB using SMIv2

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Table of Contents

 1. Introduction ..............................................    2
 2. The SNMP Network Management Framework .....................    2
 2.1 Object Definitions .......................................    2
 3. Overview ..................................................    3
 3.1 Terms ....................................................    4
 3.2 Relationship to Community Strings ........................    5
 3.3 Relationship to Proxy Mechanisms .........................    5
 3.4 Relationship to a Chassis MIB ............................    5
 3.5 Relationship to the Interfaces MIB .......................    6
 3.6 Relationship to the Other MIBs ...........................    6
 3.7 Relationship to Naming Scopes ............................    6
 3.8 Multiple Instances of the Entity MIB .....................    7
 3.9 Re-Configuration of Entities .............................    7
 3.10 MIB Structure ...........................................    7
 3.10.1 entityPhysical Group ..................................    8
 3.10.2 entityLogical Group ...................................    8
 3.10.3 entityMapping Group ...................................    8
 3.10.4 entityGeneral Group ...................................    9
 3.10.5 entityNotifications Group .............................    9
 3.11 Multiple Agents .........................................    9
 4. Definitions ...............................................   10
 5. Usage Examples ............................................   26
 5.1 Router/Bridge ............................................   26
 5.2 Repeaters ................................................   30
 6. Acknowledgements ..........................................   33
 7. References ................................................   34
 8. Security Considerations ...................................   35
 9. Authors' Addresses ........................................   35

McCloghrie & Bierman Standards Track [Page 1] RFC 2037 Entity MIB using SMIv2 October 1996

1. Introduction

 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.

2. The SNMP Network Management Framework

 The SNMP Network Management Framework presently consists of three
 major components.  They are:
 o    the SMI, described in RFC 1902 [1], - the mechanisms used for
      describing and naming objects for the purpose of management.
 o    the MIB-II, STD 17, RFC 1213 [2], - the core set of managed
      objects for the Internet suite of protocols.
 o    the protocol, RFC 1157 [6] and/or RFC 1905 [4], - the protocol
      for accessing managed information.
 Textual conventions are defined in RFC 1903 [3], and conformance
 statements are defined in RFC 1904 [5].
 The Framework permits new objects to be defined for the purpose of
 experimentation and evaluation.
 This memo specifies a MIB module that is compliant to the SNMPv2 SMI.
 A semantically identical MIB conforming to the SNMPv1 SMI can be
 produced through the appropriate translation.

2.1. Object Definitions

 Managed objects are accessed via a virtual information store, termed
 the Management Information Base or MIB.  Objects in the MIB are
 defined using the subset of Abstract Syntax Notation One (ASN.1)
 defined in the SMI.  In particular, each object type is named by an
 OBJECT IDENTIFIER, an administratively assigned name.  The object
 type together with an object instance serves to uniquely identify a
 specific instantiation of the object.  For human convenience, we
 often use a textual string, termed the descriptor, to refer to the
 object type.

McCloghrie & Bierman Standards Track [Page 2] RFC 2037 Entity MIB using SMIv2 October 1996

3. 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:
  1. multiple instances of a bridge supported within a single

device having a single agent;

  1. multiple repeaters supported by a single agent;
  1. 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 (either by SNMPv1 or SNMPv2), 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 situations preferable, to have the context/community in the
 message identify the logical entity to which the varbinds apply.

McCloghrie & Bierman Standards Track [Page 3] RFC 2037 Entity MIB using SMIv2 October 1996

3.1. Terms

 Some new terms are used throughout this document:
  1. 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.
  1. 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.
  1. 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.
  1. 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.
  1. 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.
  1. Containment Tree

Each physical component may optionally 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.

McCloghrie & Bierman Standards Track [Page 4] RFC 2037 Entity MIB using SMIv2 October 1996

   Note that chassis slots, which are capable of accepting one or more
   module types from one or more vendors, are modeled as containers in
   this MIB. The value of entPhysicalContainedIn for a particular
   'module' entity (entPhysicalClass value of 'module(9)') must be
   equal to an entPhysicalIndex that represents the parent 'container'
   entity (associated entPhysicalClass value of ('container(5)'). An
   agent must represent both empty and full containers in the
   entPhysicalTable.

3.2. Relationship to Community Strings

 For community-based SNMP, distinguishing between different logical
 entities is one (but not the only) purpose of the community string
 [6].  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.

3.3. 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 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.

3.4. 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

McCloghrie & Bierman Standards Track [Page 5] RFC 2037 Entity MIB using SMIv2 October 1996

 entities represented by an implementation of this MIB might well be
 contained in a chassis.

3.5. 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 [7]. 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 an 'entPhysicalName' object, which
 approximates the semantics of the ifName object from the Interfaces
 MIB [7] for all types of physical components.

3.6. 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.

3.7. 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 'main' naming
 scope).
 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 'main' naming scope, as well as a
 second instance of the Bridge MIB.
 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. 'main'), which itself may
 contain some multi-scoped objects (e.g. system group).

McCloghrie & Bierman Standards Track [Page 6] RFC 2037 Entity MIB using SMIv2 October 1996

3.8. 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
 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.

3.9. Re-Configuration of Entities

 All the MIB objects defined in this MIB have at most a read-only
 MAX-ACCESS clause, i.e., none are write-able.  This is a conscious
 decision by the working group to limit this MIB's scope.  It is
 possible that this restriction could be lifted after implementation
 experience, by means of additional tables (using the AUGMENTS clause)
 for configuration and extended entity information.

3.10. MIB Structure

 The Entity MIB contains five conformance groups:
  1. entityPhysical group

Describes the physical entities managed by a single agent.

McCloghrie & Bierman Standards Track [Page 7] RFC 2037 Entity MIB using SMIv2 October 1996

  1. entityLogical group

Describes the logical entities managed by a single agent.

  1. entityMapping group

Describes the associations between the physical entities,

      logical entities, interfaces, and non-interface ports managed
      by a single agent.
  1. entityGeneral group

Describes general system attributes shared by potentially

      all types of entities managed by a single agent.
  1. entityNotifications group

Contains status indication notifications.

3.10.1. 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 contains at least one row for an "overall" physical entity.
 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.

3.10.2. 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 SNMPv1 or SNMPv2C [9] access to the MIB
 information for the logical entity.

3.10.3. entityMapping Group

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

McCloghrie & Bierman Standards Track [Page 8] RFC 2037 Entity MIB using SMIv2 October 1996

 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.
 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.

3.10.4. 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 system configuration last changed.

3.10.5. entityNotifications Group

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

3.11. 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.
 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).

McCloghrie & Bierman Standards Track [Page 9] RFC 2037 Entity MIB using SMIv2 October 1996

4. Definitions

ENTITY-MIB DEFINITIONS ::= BEGIN

IMPORTS

  MODULE-IDENTITY, OBJECT-TYPE,
  mib-2, NOTIFICATION-TYPE
      FROM SNMPv2-SMI
  TDomain, TAddress, DisplayString, TEXTUAL-CONVENTION,
  AutonomousType, RowPointer, TimeStamp
      FROM SNMPv2-TC
  MODULE-COMPLIANCE, OBJECT-GROUP
      FROM SNMPv2-CONF;

entityMIB MODULE-IDENTITY

  LAST-UPDATED "9605160000Z"
  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
                   408-526-5260
                   kzm@cisco.com
                   Andy Bierman
                   ENTMIB Working Group Editor
                   Cisco Systems Inc.
                   170 West Tasman Drive
                   San Jose, CA 95134
                   408-527-3711
                   abierman@cisco.com"
  DESCRIPTION
          "The MIB module for representing multiple logical
          entities supported by a single SNMP agent."
  ::= { mib-2 47 }

entityMIBObjects OBJECT IDENTIFIER ::= { entityMIB 1 }

– MIB contains four groups

entityPhysical OBJECT IDENTIFIER ::= { entityMIBObjects 1 } entityLogical OBJECT IDENTIFIER ::= { entityMIBObjects 2 }

McCloghrie & Bierman Standards Track [Page 10] RFC 2037 Entity MIB using SMIv2 October 1996

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 is 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."
  SYNTAX      INTEGER  {
      other(1),
      unknown(2),
      chassis(3),
      backplane(4),
      container(5),   -- e.g. slot or daughter-card holder
      powerSupply(6),
      fan(7),
      sensor(8),
      module(9),      -- e.g. plug-in card or daughter-card
      port(10)
  }

– The Physical Entity Table

entPhysicalTable OBJECT-TYPE

  SYNTAX      SEQUENCE OF EntPhysicalEntry
  MAX-ACCESS  not-accessible
  STATUS      current
  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

McCloghrie & Bierman Standards Track [Page 11] RFC 2037 Entity MIB using SMIv2 October 1996

  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          DisplayString,
    entPhysicalVendorType     AutonomousType,
    entPhysicalContainedIn    INTEGER,
    entPhysicalClass          PhysicalClass,
    entPhysicalParentRelPos   INTEGER,
    entPhysicalName           DisplayString

}

entPhysicalIndex OBJECT-TYPE

  SYNTAX      PhysicalIndex
  MAX-ACCESS  not-accessible
  STATUS      current
  DESCRIPTION
          "The index for this entry."
  ::= { entPhysicalEntry 1 }

entPhysicalDescr OBJECT-TYPE

  SYNTAX      DisplayString
  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

McCloghrie & Bierman Standards Track [Page 12] RFC 2037 Entity MIB using SMIv2 October 1996

          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
          allowed."
  ::= { 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)

McCloghrie & Bierman Standards Track [Page 13] RFC 2037 Entity MIB using SMIv2 October 1996

  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 module
          labeled as 'card #3', entPhysicalParentRelPos should have
          the value '3'.
          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.

McCloghrie & Bierman Standards Track [Page 14] RFC 2037 Entity MIB using SMIv2 October 1996

          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      DisplayString
  MAX-ACCESS  read-only
  STATUS      current
  DESCRIPTION
          "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 }

– 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.  At least
          one entry must exist."
  ::= { 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 }

McCloghrie & Bierman Standards Track [Page 15] RFC 2037 Entity MIB using SMIv2 October 1996

EntLogicalEntry ::= SEQUENCE {

    entLogicalIndex            INTEGER,
    entLogicalDescr            DisplayString,
    entLogicalType             AutonomousType,
    entLogicalCommunity        OCTET STRING,
    entLogicalTAddress         TAddress,
    entLogicalTDomain          TDomain

}

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 is a small positive integer; index values
          for different logical entities are are not necessarily
          contiguous."
  ::= { entLogicalEntry 1 }

entLogicalDescr OBJECT-TYPE

  SYNTAX      DisplayString
  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 }

McCloghrie & Bierman Standards Track [Page 16] RFC 2037 Entity MIB using SMIv2 October 1996

entLogicalCommunity OBJECT-TYPE

  SYNTAX      OCTET STRING (SIZE (1..255))
  MAX-ACCESS  read-only
  STATUS      current
  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 choose to return a community string
          based on the privileges of the request used to read this
          object.  Note that an agent may choose to return a community
          string with read-only privileges, even if this object is
          accessed with a read-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 'main'
          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 'main'
          naming scope.
          For agents not accessible via SNMPv1 or SNMPv2C, the value
          of this object is the empty-string."
  ::= { 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
          the last 2 containing the UDP port in network-byte order.
          Consult 'Transport Mappings for Version 2 of the Simple

McCloghrie & Bierman Standards Track [Page 17] RFC 2037 Entity MIB using SMIv2 October 1996

          Network Management Protocol' (RFC 1906 [8]) 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 [8])."
  ::= { entLogicalEntry 6 }

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
          each bridge and the ports it used would be appropriate.
          Also, in the case of a single backplane repeater, a mapping

McCloghrie & Bierman Standards Track [Page 18] RFC 2037 Entity MIB using SMIv2 October 1996

          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
          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 }

McCloghrie & Bierman Standards Track [Page 19] RFC 2037 Entity MIB using SMIv2 October 1996

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 uniquely 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
          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:

McCloghrie & Bierman Standards Track [Page 20] RFC 2037 Entity MIB using SMIv2 October 1996

                  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
          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 }

McCloghrie & Bierman Standards Track [Page 21] RFC 2037 Entity MIB using SMIv2 October 1996

– 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 equivalent
          information found by constructing the virtual containment
          tree for a given entPhysicalTable but in a more direct
          format."
  ::= { 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

}

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 any of these events
          occur:
              * a conceptual row is created or deleted in any
                of these tables:
                  - entPhysicalTable
                  - entLogicalTable
                  - entLPMappingTable

McCloghrie & Bierman Standards Track [Page 22] RFC 2037 Entity MIB using SMIv2 October 1996

  1. entAliasMappingTable
  2. entPhysicalContainsTable
  • any instance in the following list of objects

changes value:

  1. entPhysicalDescr
  2. entPhysicalVendorType
  3. entPhysicalContainedIn
  4. entPhysicalClass
  5. entPhysicalParentRelPos
  6. entPhysicalName
  7. entLogicalDescr
  8. entLogicalType
  9. entLogicalCommunity
  10. entLogicalTAddress
  11. entLogicalTDomain
  12. entAliasMappingIdentifier "

::= { entityGeneral 1 }

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

entConfigChange NOTIFICATION-TYPE

  STATUS             current
  DESCRIPTION
          "An entConfigChange trap is sent when the value of
          entLastChangeTime changes. It can be utilized by an NMS to
          trigger logical/physical entity table maintenance polls.
          An agent must not generate more than one entConfigChange
          'trap-event' in a five second period, where a 'trap-event'
          is the transmission of a single trap PDU to a list of trap
          destinations.  If additional configuration changes occur
          within the five second 'throttling' period, then these
          trap-events should be suppressed by the agent. An NMS should
          periodically check the value of entLastChangeTime to detect
          any missed entConfigChange trap-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

McCloghrie & Bierman Standards Track [Page 23] RFC 2037 Entity MIB using SMIv2 October 1996

entityCompliance MODULE-COMPLIANCE

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

– 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  current
  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 }

entityMappingGroup OBJECT-GROUP

  OBJECTS {

McCloghrie & Bierman Standards Track [Page 24] RFC 2037 Entity MIB using SMIv2 October 1996

            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 }

END

McCloghrie & Bierman Standards Track [Page 25] RFC 2037 Entity MIB using SMIv2 October 1996

5. 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.

5.1. 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'
  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'
    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'
  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'
    entPhysicalDescr.5 ==             "Acme Ethernet-100 Port Rev G"

McCloghrie & Bierman Standards Track [Page 26] RFC 2037 Entity MIB using SMIv2 October 1996

    entPhysicalVendorType.5  ==       acmeProducts.portTypes.2
    entPhysicalContainedIn.5 ==       4
    entPhysicalClass.5 ==             port(10)
    entPhysicalParentRelPos.5 ==      1
    entPhysicalName.5 ==              'P1'
    entPhysicalDescr.6 ==             "Acme Ethernet-100 Port Rev G"
    entPhysicalVendorType.6  ==       acmeProducts.portTypes.2
    entPhysicalContainedIn.6 ==       4
    entPhysicalClass.6 ==             port(10)
    entPhysicalParentRelPos.6 ==      2
    entPhysicalName.6 ==              'P2'
    entPhysicalDescr.7 ==             "Acme Router-100 F-Port: Rev B"
    entPhysicalVendorType.7  ==       acmeProducts.portTypes.3
    entPhysicalContainedIn.7 ==       4
    entPhysicalClass.7 ==             port(10)
    entPhysicalParentRelPos.7 ==      3
    entPhysicalName.7 ==              'P3'
 Slot 2 contains another 3-port module:
    entPhysicalDescr.8 ==             "Acme Router-100 Comm Module: Rev C"
    entPhysicalVendorType.8  ==       acmeProducts.moduleTypes.15
    entPhysicalContainedIn.8 ==       3
    entPhysicalClass.8 ==             module(9)
    entPhysicalParentRelPos.8 ==      1
    entPhysicalName.8 ==              'M2'
    entPhysicalDescr.9 ==             "Acme Fddi-100 Port Rev CC"
    entPhysicalVendorType.9 ==        acmeProducts.portTypes.5
    entPhysicalContainedIn.9 ==       8
    entPhysicalClass.9 ==             port(10)
    entPhysicalParentRelPos.9 ==      1
    entPhysicalName.9 ==              'FDDI Primary'
    entPhysicalDescr.10 ==            "Acme Ethernet-100 Port Rev G"
    entPhysicalVendorType.10 ==       acmeProducts.portTypes.2
    entPhysicalContainedIn.10 ==      8
    entPhysicalClass.10 ==            port(10)
    entPhysicalParentRelPos.10 ==     2
    entPhysicalName.10 ==             'Ethernet A'
    entPhysicalDescr.11 ==            "Acme Ethernet-100 Port Rev G"
    entPhysicalVendorType.11 ==       acmeProducts.portTypes.2
    entPhysicalContainedIn.11 ==      8
    entPhysicalClass.11 ==            port(10)
    entPhysicalParentRelPos.11 ==     3
    entPhysicalName.11 ==             'Ethernet B'

McCloghrie & Bierman Standards Track [Page 27] RFC 2037 Entity MIB using SMIv2 October 1996

 Logical entities -- entLogicalTable
  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
    entLogicalDescr.2 ==            "Acme OSPF v1.1"
    entLogicalType.2 ==             ospf
    entLogicalCommunity.2 ==        "public-ospf2"
    entLogicalTAddress.2 ==         124.125.126.127:161
    entLogicalTDomain.2 ==          snmpUDPDomain
  2 logical bridges:
    entLogicalDescr.3 ==            "Acme Bridge v2.1.1"
    entLogicalType.3  ==            dod1dBridge
    entLogicalCommunity.3 ==        "public-bridge1"
    entLogicalTAddress.3 ==         124.125.126.127:161
    entLogicalTDomain.3 ==          snmpUDPDomain
    entLogicalDescr.4 ==            "Acme Bridge v2.1.1"
    entLogicalType.4 ==             dod1dBridge
    entLogicalCommunity.4 ==        "public-bridge2"
    entLogicalTAddress.4 ==         124.125.126.127:161
    entLogicalTDomain.4 ==          snmpUDPDomain

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

McCloghrie & Bierman Standards Track [Page 28] RFC 2037 Entity MIB using SMIv2 October 1996

    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
    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

McCloghrie & Bierman Standards Track [Page 29] RFC 2037 Entity MIB using SMIv2 October 1996

5.2. Repeaters

 A 3-slot Hub with 2 backplane ethernet segments.  Slot three is
 empty, and the remaining slots contain ethernet repeater modules.
 [ed. -- Note that a replacement for the current Repeater MIB (RFC
 1516) is likely to emerge soon, and it will no longer be necessary to
 access repeater MIB data in different naming scopes.]

Physical entities – entPhysicalTable:

 1 Field-replaceable physical chassis:
    entPhysicalDescr.1 ==          "Acme Chassis Model 110"
    entPhysicalVendorType.1 ==     acmeProducts.chassisTypes.2
    entPhysicalContainedIn.1 ==    0
    entPhysicalClass.1 ==          chassis(3)
    entPhysicalParentRelPos.1 ==   0
    entPhysicalName.1 ==           '110-B'
 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'
    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'
 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'
    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'
    entPhysicalDescr.6 ==          "Acme Hub Slot Type RB"

McCloghrie & Bierman Standards Track [Page 30] RFC 2037 Entity MIB using SMIv2 October 1996

    entPhysicalVendorType.6  ==    acmeProducts.slotTypes.5
    entPhysicalContainedIn.6 ==    1
    entPhysicalClass.6 ==          container(5)
    entPhysicalParentRelPos.6 ==   3
    entPhysicalName.6 ==           'Slot 3'
 Slot 1 contains a plug-in module with 4 10-BaseT ports:
    entPhysicalDescr.7  ==         "Acme 10Base-T Module 114 Rev A"
    entPhysicalVendorType.7   ==   acmeProducts.moduleTypes.32
    entPhysicalContainedIn.7  ==   4
    entPhysicalClass.7 ==          module(9)
    entPhysicalParentRelPos.7 ==   1
    entPhysicalName.7 ==           'M1'
    entPhysicalDescr.8  ==         "Acme 10Base-T Port RB Rev A"
    entPhysicalVendorType.8   ==   acmeProducts.portTypes.10
    entPhysicalContainedIn.8  ==   7
    entPhysicalClass.8 ==          port(10)
    entPhysicalParentRelPos.8 ==   1
    entPhysicalName.8 ==           'Ethernet-A'
    entPhysicalDescr.9  ==         "Acme 10Base-T Port RB Rev A"
    entPhysicalVendorType.9   ==   acmeProducts.portTypes.10
    entPhysicalContainedIn.9  ==   7
    entPhysicalClass.9 ==          port(10)
    entPhysicalParentRelPos.9 ==   2
    entPhysicalName.9 ==           'Ethernet-B'
    entPhysicalDescr.10 ==         "Acme 10Base-T Port RB Rev B"
    entPhysicalVendorType.10  ==   acmeProducts.portTypes.10
    entPhysicalContainedIn.10 ==   7
    entPhysicalClass.10 ==         port(10)
    entPhysicalParentRelPos.10 ==  3
    entPhysicalName.10 ==          'Ethernet-C'
    entPhysicalDescr.11 ==         "Acme 10Base-T Port RB Rev B"
    entPhysicalVendorType.11  ==   acmeProducts.portTypes.10
    entPhysicalContainedIn.11 ==   7
    entPhysicalClass.11 ==         port(10)
    entPhysicalParentRelPos.11 ==  4
    entPhysicalName.11 ==          'Ethernet-D'
 Slot 2 contains another ethernet module with 2 ports.
    entPhysicalDescr.12 ==         "Acme 10Base-T Module Model 4 Rev A"
    entPhysicalVendorType.12 ==    acmeProducts.moduleTypes.30
    entPhysicalContainedIn.12 =    5
    entPhysicalClass.12 ==         module(9)
    entPhysicalParentRelPos.12 ==  1

McCloghrie & Bierman Standards Track [Page 31] RFC 2037 Entity MIB using SMIv2 October 1996

    entPhysicalName.12 ==          'M2'
    entPhysicalDescr.13 ==         "Acme 802.3 AUI Port Rev A"
    entPhysicalVendorType.13  ==   acmeProducts.portTypes.11
    entPhysicalContainedIn.13 ==   12
    entPhysicalClass.13 ==         port(10)
    entPhysicalParentRelPos.13 ==  1
    entPhysicalName.13 ==          'AUI'
    entPhysicalDescr.14 ==         "Acme 10Base-T Port RD Rev B"
    entPhysicalVendorType.14  ==   acmeProducts.portTypes.14
    entPhysicalContainedIn.14 ==   12
    entPhysicalClass.14 ==         port(10)
    entPhysicalParentRelPos.14 ==  2
    entPhysicalName.14 ==          'E2'

Logical entities – entLogicalTable

 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
 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

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

McCloghrie & Bierman Standards Track [Page 32] RFC 2037 Entity MIB using SMIv2 October 1996

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
    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

6. Acknowledgements

 This document was produced by the IETF Entity MIB Working Group.

McCloghrie & Bierman Standards Track [Page 33] RFC 2037 Entity MIB using SMIv2 October 1996

7. References

[1] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Structure of Management Information for version 2
   of the Simple Network Management Protocol (SNMPv2)", RFC 1902,
   January 1996.

[2] McCloghrie, K., and M. Rose, Editors, "Management Information Base

   for Network Management of TCP/IP-based internets: MIB-II", STD 17,
   RFC 1213, Hughes LAN Systems, Performance Systems International,
   March 1991.

[3] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Textual Conventions for version 2 of the Simple
   Network Management Protocol (SNMPv2)", RFC 1903, January 1996.

[4] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Protocol Operations for version 2 of the Simple
   Network Management Protocol (SNMPv2)", RFC 1905, January 1996.

[5] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Conformance Statements for version 2 of the Simple
   Network Management Protocol (SNMPv2)", RFC 1904, January 1996.

[6] Case, J., M. Fedor, M. Schoffstall, J. Davin, "Simple Network

   Management Protocol", RFC 1157, SNMP Research, Performance Systems
   International, MIT Laboratory for Computer Science, May 1990.

[7] McCloghrie, K., and Kastenholtz, F., "Interfaces Group Evolution",

   RFC 1573, Hughes LAN Systems, FTP Software, January 1994.

[8] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Transport Mappings for version 2 of the Simple
   Network Management Protocol (SNMPv2)", RFC 1906, January 1996.

[9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and

   S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901,
   January 1996.

McCloghrie & Bierman Standards Track [Page 34] RFC 2037 Entity MIB using SMIv2 October 1996

8. Security Considerations

 In order to implement this MIB, an agent must make certain management
 information available about various logical and physical entities
 within a managed system, which may be considered sensitive in some
 network environments.
 Therefore, a network administrator may wish to employ instance-level
 access control, and configure the Entity MIB access (i.e., community
 strings in SNMPv1 and SNMPv2C), such that certain instances within
 this MIB (e.g., entLogicalCommunity, or entire entLogicalEntries,
 entPhysicalEntries, and associated mapping table entries), are
 excluded from particular MIB views.

9. Authors' Addresses

 Keith McCloghrie
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA 95134
 Phone: 408-526-5260
 EMail: kzm@cisco.com
 Andy Bierman
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA 95134
 Phone: 408-527-3711
 EMail: abierman@cisco.com

McCloghrie & Bierman Standards Track [Page 35]

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