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rfc:rfc2580

Network Working Group Editors of this version: Request for Comments: 2580 K. McCloghrie STD: 58 Cisco Systems Obsoletes: 1904 D. Perkins Category: Standards Track SNMPinfo

                                                      J. Schoenwaelder
                                                       TU Braunschweig
                                    Authors of previous version:
                                                               J. Case
                                                         SNMP Research
                                                         K. McCloghrie
                                                         Cisco Systems
                                                               M. Rose
                                                First Virtual Holdings
                                                         S. Waldbusser
                                        International Network Services
                                                            April 1999
                  Conformance Statements for 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.

Copyright Notice

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

Table of Contents

 1 Introduction .....................................................3
 1.1 A Note on Terminology ..........................................3
 2 Definitions ......................................................3
 2.1 The OBJECT-GROUP macro .........................................3
 2.2 The NOTIFICATION-GROUP macro ...................................4
 2.3 The MODULE-COMPLIANCE macro ....................................5
 2.4 The AGENT-CAPABILITIES macro ...................................7
 3 Mapping of the OBJECT-GROUP macro ...............................10
 3.1 Mapping of the OBJECTS clause .................................10
 3.2 Mapping of the STATUS clause ..................................11
 3.3 Mapping of the DESCRIPTION clause .............................11
 3.4 Mapping of the REFERENCE clause ...............................11

McCloghrie, et al. Standards Track [Page 1]

RFC 2580 Conformance Statements for SMIv2 April 1999

 3.5 Mapping of the OBJECT-GROUP value .............................11
 3.6 Usage Example .................................................12
 4 Mapping of the NOTIFICATION-GROUP macro .........................12
 4.1 Mapping of the NOTIFICATIONS clause ...........................12
 4.2 Mapping of the STATUS clause ..................................13
 4.3 Mapping of the DESCRIPTION clause .............................13
 4.4 Mapping of the REFERENCE clause ...............................13
 4.5 Mapping of the NOTIFICATION-GROUP value .......................13
 4.6 Usage Example .................................................13
 5 Mapping of the MODULE-COMPLIANCE macro ..........................14
 5.1 Mapping of the STATUS clause ..................................14
 5.2 Mapping of the DESCRIPTION clause .............................14
 5.3 Mapping of the REFERENCE clause ...............................15
 5.4 Mapping of the MODULE clause ..................................15
 5.4.1 Mapping of the MANDATORY-GROUPS clause ......................15
 5.4.2 Mapping of the GROUP clause .................................15
 5.4.3 Mapping of the OBJECT clause ................................16
 5.4.3.1 Mapping of the SYNTAX clause ..............................16
 5.4.3.2 Mapping of the WRITE-SYNTAX clause ........................16
 5.4.3.3 Mapping of the MIN-ACCESS clause ..........................16
 5.4.4 Mapping of the DESCRIPTION clause ...........................17
 5.5 Mapping of the MODULE-COMPLIANCE value ........................17
 5.6 Usage Example .................................................17
 6 Mapping of the AGENT-CAPABILITIES macro .........................19
 6.1 Mapping of the PRODUCT-RELEASE clause .........................19
 6.2 Mapping of the STATUS clause ..................................19
 6.3 Mapping of the DESCRIPTION clause .............................20
 6.4 Mapping of the REFERENCE clause ...............................20
 6.5 Mapping of the SUPPORTS clause ................................20
 6.5.1 Mapping of the INCLUDES clause ..............................20
 6.5.2 Mapping of the VARIATION clause .............................20
 6.5.2.1 Mapping of the SYNTAX clause ..............................21
 6.5.2.2 Mapping of the WRITE-SYNTAX clause ........................21
 6.5.2.3 Mapping of the ACCESS clause ..............................21
 6.5.2.4 Mapping of the CREATION-REQUIRES clause ...................22
 6.5.2.5 Mapping of the DEFVAL clause ..............................22
 6.5.2.6 Mapping of the DESCRIPTION clause .........................22
 6.6 Mapping of the AGENT-CAPABILITIES value .......................22
 6.7 Usage Example .................................................23
 7 Extending an Information Module .................................25
 7.1 Conformance Groups ............................................25
 7.2 Compliance Definitions ........................................26
 7.3 Capabilities Definitions ......................................26
 8 Security Considerations .........................................27
 9 Editors' Addresses ..............................................27
 10 References .....................................................28
 11 Full Copyright Statement .......................................29

McCloghrie, et al. Standards Track [Page 2]

RFC 2580 Conformance Statements for SMIv2 April 1999

1. Introduction

 Management information is viewed as a collection of managed objects,
 residing in a virtual information store, termed the Management
 Information Base (MIB).  Collections of related objects are defined
 in MIB modules.  These modules are written using an adapted subset of
 OSI's Abstract Syntax Notation One, ASN.1 (1988) [1], termed the
 Structure of Management Information (SMI) [2].
 It may be useful to define the acceptable lower-bounds of
 implementation, along with the actual level of implementation
 achieved.  It is the purpose of this document to define the notation
 used for these purposes.

1.1. A Note on Terminology

 For the purpose of exposition, the original Structure of Management
 Information, as described in RFCs 1156 (STD 16), 1212 (STD 16), and
 RFC 1215, is termed the SMI version 1 (SMIv1).  The current version
 of the Structure of Management Information is termed SMI version 2
 (SMIv2).

2. Definitions

SNMPv2-CONF DEFINITIONS ::= BEGIN

IMPORTS ObjectName, NotificationName, ObjectSyntax

                                             FROM SNMPv2-SMI;

– definitions for conformance groups

OBJECT-GROUP MACRO ::= BEGIN

  TYPE NOTATION ::=
                ObjectsPart
                "STATUS" Status
                "DESCRIPTION" Text
                ReferPart
  VALUE NOTATION ::=
                value(VALUE OBJECT IDENTIFIER)
  ObjectsPart ::=
                "OBJECTS" "{" Objects "}"
  Objects ::=
                Object
              | Objects "," Object
  Object ::=

McCloghrie, et al. Standards Track [Page 3]

RFC 2580 Conformance Statements for SMIv2 April 1999

                value(ObjectName)
  Status ::=
                "current"
              | "deprecated"
              | "obsolete"
  ReferPart ::=
                "REFERENCE" Text
              | empty
  1. - a character string as defined in [2]

Text ::= value(IA5String) END

– more definitions for conformance groups

NOTIFICATION-GROUP MACRO ::= BEGIN

  TYPE NOTATION ::=
                NotificationsPart
                "STATUS" Status
                "DESCRIPTION" Text
                ReferPart
  VALUE NOTATION ::=
                value(VALUE OBJECT IDENTIFIER)
  NotificationsPart ::=
                "NOTIFICATIONS" "{" Notifications "}"
  Notifications ::=
                Notification
              | Notifications "," Notification
  Notification ::=
                value(NotificationName)
  Status ::=
                "current"
              | "deprecated"
              | "obsolete"
  ReferPart ::=
                "REFERENCE" Text
              | empty
  1. - a character string as defined in [2]

Text ::= value(IA5String) END

McCloghrie, et al. Standards Track [Page 4]

RFC 2580 Conformance Statements for SMIv2 April 1999

– definitions for compliance statements

MODULE-COMPLIANCE MACRO ::= BEGIN

  TYPE NOTATION ::=
                "STATUS" Status
                "DESCRIPTION" Text
                ReferPart
                ModulePart
  VALUE NOTATION ::=
                value(VALUE OBJECT IDENTIFIER)
  Status ::=
                "current"
              | "deprecated"
              | "obsolete"
  ReferPart ::=
                "REFERENCE" Text
              | empty
  ModulePart ::=
                Modules
  Modules ::=
                Module
              | Modules Module
  Module ::=
                -- name of module --
                "MODULE" ModuleName
                MandatoryPart
                CompliancePart
  ModuleName ::=
                -- identifier must start with uppercase letter
                identifier ModuleIdentifier
                -- must not be empty unless contained
                -- in MIB Module
              | empty
  ModuleIdentifier ::=
                value(OBJECT IDENTIFIER)
              | empty
  MandatoryPart ::=
                "MANDATORY-GROUPS" "{" Groups "}"
              | empty
  Groups ::=

McCloghrie, et al. Standards Track [Page 5]

RFC 2580 Conformance Statements for SMIv2 April 1999

                Group
              | Groups "," Group
  Group ::=
                value(OBJECT IDENTIFIER)
  CompliancePart ::=
                Compliances
              | empty
  Compliances ::=
                Compliance
              | Compliances Compliance
  Compliance ::=
                ComplianceGroup
              | Object
  ComplianceGroup ::=
                "GROUP" value(OBJECT IDENTIFIER)
                "DESCRIPTION" Text
  Object ::=
                "OBJECT" value(ObjectName)
                SyntaxPart
                WriteSyntaxPart
                AccessPart
                "DESCRIPTION" Text
  1. - must be a refinement for object's SYNTAX clause

SyntaxPart ::= "SYNTAX" Syntax

              | empty
  1. - must be a refinement for object's SYNTAX clause

WriteSyntaxPart ::= "WRITE-SYNTAX" Syntax

              | empty
  Syntax ::=    -- Must be one of the following:
                     -- a base type (or its refinement),
                     -- a textual convention (or its refinement), or
                     -- a BITS pseudo-type
                type
              | "BITS" "{" NamedBits "}"
  NamedBits ::= NamedBit
              | NamedBits "," NamedBit
  NamedBit ::= identifier "(" number ")" -- number is nonnegative
  AccessPart ::=

McCloghrie, et al. Standards Track [Page 6]

RFC 2580 Conformance Statements for SMIv2 April 1999

                "MIN-ACCESS" Access
              | empty
  Access ::=
                "not-accessible"
              | "accessible-for-notify"
              | "read-only"
              | "read-write"
              | "read-create"
  1. - a character string as defined in [2]

Text ::= value(IA5String) END

– definitions for capabilities statements

AGENT-CAPABILITIES MACRO ::= BEGIN

  TYPE NOTATION ::=
                "PRODUCT-RELEASE" Text
                "STATUS" Status
                "DESCRIPTION" Text
                ReferPart
                ModulePart
  VALUE NOTATION ::=
                value(VALUE OBJECT IDENTIFIER)
  Status ::=
                "current"
              | "obsolete"
  ReferPart ::=
                "REFERENCE" Text
              | empty
  ModulePart ::=
                Modules
              | empty
  Modules ::=
                Module
              | Modules Module
  Module ::=
                -- name of module --
                "SUPPORTS" ModuleName
                "INCLUDES" "{" Groups "}"
                VariationPart
  ModuleName ::=

McCloghrie, et al. Standards Track [Page 7]

RFC 2580 Conformance Statements for SMIv2 April 1999

  1. - identifier must start with uppercase letter

identifier ModuleIdentifier

  ModuleIdentifier ::=
                value(OBJECT IDENTIFIER)
              | empty
  Groups ::=
                Group
              | Groups "," Group
  Group ::=
                value(OBJECT IDENTIFIER)
  VariationPart ::=
                Variations
              | empty
  Variations ::=
                Variation
              | Variations Variation
  Variation ::=
                ObjectVariation
              | NotificationVariation
  NotificationVariation ::=
                "VARIATION" value(NotificationName)
                AccessPart
                "DESCRIPTION" Text
  ObjectVariation ::=
                "VARIATION" value(ObjectName)
                SyntaxPart
                WriteSyntaxPart
                AccessPart
                CreationPart
                DefValPart
                "DESCRIPTION" Text
  1. - must be a refinement for object's SYNTAX clause

SyntaxPart ::= "SYNTAX" Syntax

              | empty
  WriteSyntaxPart ::= "WRITE-SYNTAX" Syntax
              | empty
  Syntax ::=    -- Must be one of the following:
                     -- a base type (or its refinement),
                     -- a textual convention (or its refinement), or
                     -- a BITS pseudo-type

McCloghrie, et al. Standards Track [Page 8]

RFC 2580 Conformance Statements for SMIv2 April 1999

                type
              | "BITS" "{" NamedBits "}"
  NamedBits ::= NamedBit
              | NamedBits "," NamedBit
  NamedBit ::= identifier "(" number ")" -- number is nonnegative
  AccessPart ::=
                "ACCESS" Access
              | empty
  Access ::=
                "not-implemented"
              -- only "not-implemented" for notifications
              | "accessible-for-notify"
              | "read-only"
              | "read-write"
              | "read-create"
              -- following is for backward-compatibility only
              | "write-only"
  CreationPart ::=
                "CREATION-REQUIRES" "{" Cells "}"
              | empty
  Cells ::=
                Cell
              | Cells "," Cell
  Cell ::=
                value(ObjectName)
  DefValPart ::= "DEFVAL" "{" Defvalue "}"
              | empty
  Defvalue ::=  -- must be valid for the object's syntax
                -- in this macro's SYNTAX clause, if present,
                -- or if not, in object's OBJECT-TYPE macro
                value(ObjectSyntax)
              | "{" BitsValue "}"
  BitsValue ::= BitNames
              | empty
  BitNames ::=  BitName
              | BitNames "," BitName
  BitName ::= identifier

McCloghrie, et al. Standards Track [Page 9]

RFC 2580 Conformance Statements for SMIv2 April 1999

  1. - a character string as defined in [2]

Text ::= value(IA5String) END

END

3. Mapping of the OBJECT-GROUP macro

 For conformance purposes, it is useful to define a collection of
 related managed objects.  The OBJECT-GROUP macro is used to define
 each such collection of related objects.  It should be noted that the
 expansion of the OBJECT-GROUP macro is something which conceptually
 happens during implementation and not during run-time.
 To "implement" an object, an agent must return a reasonably accurate
 value for management protocol retrieval operations; similarly, if the
 object is writable, then in response to a management protocol set
 operation, an agent must accordingly be able to reasonably influence
 the underlying managed entity.  If an agent can not implement an
 object, the management protocol provides for it to return an
 exception or error, e.g, noSuchObject [4].  Under no circumstances
 shall an agent return a value for objects which it does not implement
 -- it must always return the appropriate exception or error, as
 described in the protocol specification [4].
 Note that the OBJECT-GROUP macro itself provides no conformance
 information.  Rather, conformance information is specified through
 the inclusion of defined groups in a MODULE-COMPLIANCE macro.

3.1. Mapping of the OBJECTS clause

 The OBJECTS clause, which must be present, is used to specify each
 object contained in the conformance group.  Each of the specified
 objects must be defined in the same information module as the
 OBJECT-GROUP macro appears, and must have a MAX-ACCESS clause value
 of "accessible-for-notify", "read-only", "read-write", or "read-
 create".
 It is required that every object defined in an information module
 with a MAX-ACCESS clause other than "not-accessible" be contained in
 at least one object group.  This avoids the common error of adding a
 new object to an information module and forgetting to add the new
 object to a group.

McCloghrie, et al. Standards Track [Page 10]

RFC 2580 Conformance Statements for SMIv2 April 1999

3.2. Mapping of the STATUS clause

 The STATUS clause, which must be present, indicates whether this
 definition is current or historic.
 The value "current" means that the definition is current and valid.
 The value "obsolete" means the definition is obsolete and the group
 should no longer be used for defining conformance.  While the value
 "deprecated" also indicates an obsolete definition, it permits
 new/continued use of conformance definitions using this group.

3.3. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause, which must be present, contains a textual
 definition of that group, along with a description of any relations
 to other groups.  Note that generic compliance requirements should
 not be stated in this clause.  However, implementation relationships
 between this group and other groups may be defined in this clause.

3.4. Mapping of the REFERENCE clause

 The REFERENCE clause, which need not be present, contains a textual
 cross-reference to some other document, either another information
 module which defines a related assignment, or some other document
 which provides additional information relevant to this definition.

3.5. Mapping of the OBJECT-GROUP value

 The value of an invocation of the OBJECT-GROUP macro is the name of
 the group, which is an OBJECT IDENTIFIER, an administratively
 assigned name.

McCloghrie, et al. Standards Track [Page 11]

RFC 2580 Conformance Statements for SMIv2 April 1999

3.6. Usage Example

 The SNMP Group [3] is described:
 snmpGroup OBJECT-GROUP
     OBJECTS { snmpInPkts,
               snmpInBadVersions,
               snmpInASNParseErrs,
               snmpBadOperations,
               snmpSilentDrops,
               snmpProxyDrops,
               snmpEnableAuthenTraps }
     STATUS  current
     DESCRIPTION
             "A collection of objects providing basic instrumentation
             and control of an agent."
    ::= { snmpMIBGroups 8 }
 According to this invocation, the conformance group named
      { snmpMIBGroups 8 }
 contains 7 objects.

4. Mapping of the NOTIFICATION-GROUP macro

 For conformance purposes, it is useful to define a collection of
 notifications.  The NOTIFICATION-GROUP macro serves this purpose.  It
 should be noted that the expansion of the NOTIFICATION-GROUP macro is
 something which conceptually happens during implementation and not
 during run-time.

4.1. Mapping of the NOTIFICATIONS clause

 The NOTIFICATIONS clause, which must be present, is used to specify
 each notification contained in the conformance group.  Each of the
 specified notifications must be defined in the same information
 module as the NOTIFICATION-GROUP macro appears.
 It is required that every notification defined in an information
 module be contained in at least one notification group.

McCloghrie, et al. Standards Track [Page 12]

RFC 2580 Conformance Statements for SMIv2 April 1999

4.2. Mapping of the STATUS clause

 The STATUS clause, which must be present, indicates whether this
 definition is current or historic.
 The value "current" means that the definition is current and valid.
 The value "obsolete" means the definition is obsolete and this group
 should no longer be used for defining conformance.  While the value
 "deprecated" also indicates an obsolete definition, it permits
 new/continued use of conformance definitions using this group.

4.3. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause, which must be present, contains a textual
 definition of the group, along with a description of any relations to
 other groups.  Note that generic compliance requirements should not
 be stated in this clause.  However, implementation relationships
 between this group and other groups may be defined in this clause.

4.4. Mapping of the REFERENCE clause

 The REFERENCE clause, which need not be present, contains a textual
 cross-reference to some other document, either another information
 module which defines a related assignment, or some other document
 which provides additional information relevant to this definition.

4.5. Mapping of the NOTIFICATION-GROUP value

 The value of an invocation of the NOTIFICATION-GROUP macro is the
 name of the group, which is an OBJECT IDENTIFIER, an administratively
 assigned name.

4.6. Usage Example

 The SNMP Basic Notifications Group [3] is described:

McCloghrie, et al. Standards Track [Page 13]

RFC 2580 Conformance Statements for SMIv2 April 1999

 snmpBasicNotificationsGroup NOTIFICATION-GROUP
     NOTIFICATIONS { coldStart, authenticationFailure }
     STATUS        current
     DESCRIPTION
             "The two notifications which an agent is required to
             implement."
    ::= { snmpMIBGroups 7 }
 According to this invocation, the conformance group named
      { snmpMIBGroups 7 }
 contains 2 notifications.

5. Mapping of the MODULE-COMPLIANCE macro

 The MODULE-COMPLIANCE macro is used to convey a minimum set of
 requirements with respect to implementation of one or more MIB
 modules.  It should be noted that the expansion of the MODULE-
 COMPLIANCE macro is something which conceptually happens during
 implementation and not during run-time.
 A requirement on all "standard" MIB modules is that a corresponding
 MODULE-COMPLIANCE specification is also defined, either in the same
 information module or in a companion information module.

5.1. Mapping of the STATUS clause

 The STATUS clause, which must be present, indicates whether this
 definition is current or historic.
 The value "current" means that the definition is current and valid.
 The value "obsolete" means the definition is obsolete, and this
 MODULE-COMPLIANCE specification no longer specifies a valid
 definition of conformance.  While the value "deprecated" also
 indicates an obsolete definition, it permits new/continued use of the
 MODULE-COMPLIANCE specification.

5.2. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause, which must be present, contains a textual
 definition of this compliance statement and should embody any
 information which would otherwise be communicated in any ASN.1
 commentary annotations associated with the statement.

McCloghrie, et al. Standards Track [Page 14]

RFC 2580 Conformance Statements for SMIv2 April 1999

5.3. Mapping of the REFERENCE clause

 The REFERENCE clause, which need not be present, contains a textual
 cross-reference to some other document, either another information
 module which defines a related assignment, or some other document
 which provides additional information relevant to this definition.

5.4. Mapping of the MODULE clause

 The MODULE clause, which must be present, is repeatedly used to name
 each MIB module for which compliance requirements are being
 specified.  Each MIB module is named by its module name, and
 optionally, by its associated OBJECT IDENTIFIER as well.  The module
 name can be omitted when the MODULE-COMPLIANCE invocation occurs
 inside a MIB module, to refer to the encompassing MIB module.

5.4.1. Mapping of the MANDATORY-GROUPS clause

 The MANDATORY-GROUPS clause, which need not be present, names the one
 or more object or notification groups within the correspondent MIB
 module which are unconditionally mandatory for implementation.  If an
 agent claims compliance to the MIB module, then it must implement
 each and every object and notification within each conformance group
 listed.  That is, if an agent returns a noSuchObject exception in
 response to a management protocol get operation [4] for any object
 within any mandatory conformance group for every possible MIB view,
 or if the agent cannot generate each notification listed in any
 conformance group under the appropriate circumstances, then that
 agent is not a conformant implementation of the MIB module.

5.4.2. Mapping of the GROUP clause

 The GROUP clause, which need not be present, is repeatedly used to
 name each object and notification group which is conditionally
 mandatory for compliance to the MIB module.  The GROUP clause can
 also be used to name unconditionally optional groups.  A group named
 in a GROUP clause must be absent from the correspondent MANDATORY-
 GROUPS clause.
 Conditionally mandatory groups include those which are mandatory only
 if a particular protocol is implemented, or only if another group is
 implemented.  A GROUP clause's DESCRIPTION specifies the conditions
 under which the group is conditionally mandatory.
 A group which is named in neither a MANDATORY-GROUPS clause nor a
 GROUP clause, is unconditionally optional for compliance to the MIB
 module.

McCloghrie, et al. Standards Track [Page 15]

RFC 2580 Conformance Statements for SMIv2 April 1999

5.4.3. Mapping of the OBJECT clause

 The OBJECT clause, which need not be present, is repeatedly used to
 specify each MIB object for which compliance has a refined
 requirement with respect to the MIB module definition.  The MIB
 object must be present in one of the conformance groups named in the
 correspondent MANDATORY-GROUPS clause or GROUP clauses.
 By definition, each object specified in an OBJECT clause follows a
 MODULE clause which names the information module in which that object
 is defined.  Therefore, the use of an IMPORTS statement, to specify
 from where such objects are imported, is redundant and is not
 required in an information module.

5.4.3.1. Mapping of the SYNTAX clause

 The SYNTAX clause, which need not be present, is used to provide a
 refined SYNTAX for the object named in the correspondent OBJECT
 clause.  Note that if this clause and a WRITE-SYNTAX clause are both
 present, then this clause only applies when instances of the object
 named in the correspondent OBJECT clause are read.
 Consult Section 9 of [2] for more information on refined syntax.

5.4.3.2. Mapping of the WRITE-SYNTAX clause

 The WRITE-SYNTAX clause, which need not be present, is used to
 provide a refined SYNTAX for the object named in the correspondent
 OBJECT clause when instances of that object are written.
 Consult Section 9 of [2] for more information on refined syntax.

5.4.3.3. Mapping of the MIN-ACCESS clause

 The MIN-ACCESS clause, which need not be present, is used to define
 the minimal level of access for the object named in the correspondent
 OBJECT clause.  If this clause is absent, the minimal level of access
 is the same as the maximal level specified in the correspondent
 invocation of the OBJECT-TYPE macro.  If present, this clause must
 not specify a greater level of access than is specified in the
 correspondent invocation of the OBJECT-TYPE macro.
 The level of access for certain types of objects is fixed according
 to their syntax definition.  These types include: conceptual tables
 and rows, auxiliary objects, and objects with the syntax of
 Counter32, Counter64 (and possibly, certain types of textual
 conventions).  A MIN-ACCESS clause should not be present for such

McCloghrie, et al. Standards Track [Page 16]

RFC 2580 Conformance Statements for SMIv2 April 1999

 objects.
 An implementation is compliant if the level of access it provides is
 greater or equal to the minimal level in the MODULE-COMPLIANCE macro
 and less or equal to the maximal level in the OBJECT-TYPE macro.

5.4.4. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause must be present for each use of the GROUP or
 OBJECT clause.  For an OBJECT clause, it contains a textual
 description of the refined compliance requirement.  For a GROUP
 clause, it contains a textual description of the conditions under
 which the group is conditionally mandatory or unconditionally
 optional.

5.5. Mapping of the MODULE-COMPLIANCE value

 The value of an invocation of the MODULE-COMPLIANCE macro is an
 OBJECT IDENTIFIER.  As such, this value may be authoritatively used
 when referring to the compliance statement embodied by that
 invocation of the macro.

5.6. Usage Example

 The compliance statement contained in the (hypothetical) XYZv2-MIB
 might be:
 xyzMIBCompliance MODULE-COMPLIANCE
     STATUS  current
     DESCRIPTION
             "The compliance statement for XYZv2 entities which
             implement the XYZv2 MIB."
    MODULE  -- compliance to the containing MIB module
        MANDATORY-GROUPS { xyzSystemGroup,
                           xyzStatsGroup, xyzTrapGroup,
                           xyzSetGroup,
                           xyzBasicNotificationsGroup }
        GROUP   xyzV1Group
        DESCRIPTION
            "The xyzV1 group is mandatory only for those
             XYZv2 entities which also implement XYZv1."
::= { xyzMIBCompliances 1 }
 According to this invocation, to claim alignment with the compliance
 statement named
      { xyzMIBCompliances 1 }

McCloghrie, et al. Standards Track [Page 17]

RFC 2580 Conformance Statements for SMIv2 April 1999

 a system must implement the XYZv2-MIB's xyzSystemGroup,
 xyzStatsGroup, xyzTrapGroup, and xyzSetGroup object conformance
 groups, as well as the xyzBasicNotificationsGroup notifications
 group.  Furthermore, if the XYZv2 entity also implements XYZv1, then
 it must also support the XYZv1Group group, if compliance is to be
 claimed.

McCloghrie, et al. Standards Track [Page 18]

RFC 2580 Conformance Statements for SMIv2 April 1999

6. Mapping of the AGENT-CAPABILITIES macro

 The AGENT-CAPABILITIES macro is used to convey a set of capabilities
 present in an agent.  It should be noted that the expansion of the
 AGENT-CAPABILITIES macro is something which conceptually happens
 during implementation and not during run-time.
 When a MIB module is written, it is divided into units of conformance
 termed groups.  If an agent claims to implement a group, then it must
 implement each and every object, or each and every notification,
 within that group.  Of course, for whatever reason, an agent might
 implement only a subset of the groups within a MIB module.  In
 addition, the definition of some MIB objects/notifications leave some
 aspects of the definition to the discretion of an implementor.
 Practical experience has demonstrated a need for concisely describing
 the capabilities of an agent with respect to one or more MIB modules.
 The AGENT-CAPABILITIES macro allows an agent implementor to describe
 the precise level of support which an agent claims in regards to a
 MIB group, and to bind that description to the value of an instance
 of sysORID [3].  In particular, some objects may have restricted or
 augmented syntax or access-levels.
 If the AGENT-CAPABILITIES invocation is given to a management-station
 implementor, then that implementor can build management applications
 which optimize themselves when communicating with a particular agent.
 For example, the management-station can maintain a database of these
 invocations.  When a management-station interacts with an agent, it
 retrieves from the agent the values of all instances of sysORID [3].
 Based on this, it consults the database to locate each entry matching
 one of the retrieved values of sysORID.  Using the located entries,
 the management application can now optimize its behavior accordingly.
 Note that the AGENT-CAPABILITIES macro specifies refinements or
 variations with respect to OBJECT-TYPE and NOTIFICATION-TYPE macros
 in MIB modules, NOT with respect to MODULE-COMPLIANCE macros in
 compliance statements.

6.1. Mapping of the PRODUCT-RELEASE clause

 The PRODUCT-RELEASE clause, which must be present, contains a textual
 description of the product release which includes this set of
 capabilities.

6.2. Mapping of the STATUS clause

 The STATUS clause, which must be present, indicates whether this

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 definition is current or historic.
 The value "current" means that the definition is current and valid.
 The value "obsolete" means the definition is obsolete and this
 capabilities statement is no longer in use.

6.3. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause, which must be present, contains a textual
 description of this set of capabilities.

6.4. Mapping of the REFERENCE clause

 The REFERENCE clause, which need not be present, contains a textual
 cross-reference to some other document, either another information
 module which defines a related assignment, or some other document
 which provides additional information relevant to this definition.

6.5. Mapping of the SUPPORTS clause

 The SUPPORTS clause, which need not be present, is repeatedly used to
 name each MIB module for which the agent claims a complete or partial
 implementation.  Each MIB module is named by its module name, and
 optionally, by its associated OBJECT IDENTIFIER (as registered by the
 MODULE-IDENTITY macro, see [2]) as well.

6.5.1. Mapping of the INCLUDES clause

 The INCLUDES clause, which must follow each and every use of the
 SUPPORTS clause, is used to name each MIB group associated with the
 SUPPORTS clause, which the agent claims to implement.

6.5.2. Mapping of the VARIATION clause

 The VARIATION clause, which need not be present, is repeatedly used
 to name each object or notification which the agent implements in
 some variant or refined fashion with respect to the correspondent
 invocation of the OBJECT-TYPE or NOTIFICATION-TYPE macro.
 Note that the variation concept is meant for generic implementation
 restrictions, e.g., if the variation for an object depends on the
 values of other objects, then this should be noted in the appropriate
 DESCRIPTION clause.
 By definition, each object specified in a VARIATION clause follows a
 SUPPORTS clause which names the information module in which that
 object is defined.  Therefore, the use of an IMPORTS statement, to
 specify from where such objects are imported, is redundant and is not

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 required in an information module.

6.5.2.1. Mapping of the SYNTAX clause

 The SYNTAX clause, which need not be present, is used to provide a
 refined SYNTAX for the object named in the correspondent VARIATION
 clause.  Note that if this clause and a WRITE-SYNTAX clause are both
 present, then this clause only applies when instances of the object
 named in the correspondent VARIATION clause are read.
 Consult Section 9 of [2] for more information on refined syntax.
 Note that for enumerated INTEGERs and for the BITS construct, the
 changes allowed when updating a MIB module include the addition of
 enumerations and/or changing the labels of existing enumerations (see
 Section 10.2 of [2]).  This type of change can cause problems for an
 AGENT-CAPABILITIES macro written against the old revision of a MIB
 module.  One way to avoid such problems is to explicitly list all
 objects having an enumerated syntax in a VARIATION clause, even when
 all enumerations are currently supported.

6.5.2.2. Mapping of the WRITE-SYNTAX clause

 The WRITE-SYNTAX clause, which need not be present, is used to
 provide a refined SYNTAX for the object named in the correspondent
 VARIATION clause when instances of that object are written.
 Consult Section 9 of [2] for more information on refined syntax.

6.5.2.3. Mapping of the ACCESS clause

 The ACCESS clause, which need not be present, is used to indicate the
 agent provides less than the maximal level of access to the object or
 notification named in the correspondent VARIATION clause.
 The only value applicable to notifications is "not-implemented".
 The value "not-implemented" indicates the agent does not implement
 the object or notification, and in the ordering of possible values is
 equivalent to "not-accessible".
 The value "write-only" is provided solely for backward compatibility,
 and shall not be used for newly-defined object types.  In the
 ordering of possible values, "write-only" is less than "not-
 accessible".

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6.5.2.4. Mapping of the CREATION-REQUIRES clause

 The CREATION-REQUIRES clause, which need not be present, is used to
 name the columnar objects of a conceptual row to which values must be
 explicitly assigned, by a management protocol set operation, before
 the agent will allow the instance of the status column of that row to
 be set to `active'.  (Consult the definition of RowStatus [5].)
 If the conceptual row does not have a status column (i.e., the
 objects corresponding to the conceptual table were defined using the
 mechanisms in [6,7]), then the CREATION-REQUIRES clause, which need
 not be present, is used to name the columnar objects of a conceptual
 row to which values must be explicitly assigned, by a management
 protocol set operation, before the agent will create new instances of
 objects in that row.
 This clause must not be present unless the object named in the
 correspondent VARIATION clause is a conceptual row, i.e., has a
 syntax which resolves to a SEQUENCE containing columnar objects.  The
 objects named in the value of this clause usually will refer to
 columnar objects in that row.  However, objects unrelated to the
 conceptual row may also be specified.
 All objects which are named in the CREATION-REQUIRES clause for a
 conceptual row, and which are columnar objects of that row, must have
 an access level of "read-create".

6.5.2.5. Mapping of the DEFVAL clause

 The DEFVAL clause, which need not be present, is used to provide a
 alternate DEFVAL value for the object named in the correspondent
 VARIATION clause.  The semantics of this value are identical to those
 of the OBJECT-TYPE macro's DEFVAL clause.

6.5.2.6. Mapping of the DESCRIPTION clause

 The DESCRIPTION clause, which must be present for each use of the
 VARIATION clause, contains a textual description of the variant or
 refined implementation of the object or notification.

6.6. Mapping of the AGENT-CAPABILITIES value

 The value of an invocation of the AGENT-CAPABILITIES macro is an
 OBJECT IDENTIFIER, which names the value of sysORID [3] for which
 this capabilities statement is valid.

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6.7. Usage Example

 Consider how a capabilities statement for an agent might be
 described:
 exampleAgent AGENT-CAPABILITIES
     PRODUCT-RELEASE      "ACME Agent release 1.1 for 4BSD."
     STATUS               current
     DESCRIPTION          "ACME agent for 4BSD."
     SUPPORTS             SNMPv2-MIB
         INCLUDES         { systemGroup, snmpGroup, snmpSetGroup,
                            snmpBasicNotificationsGroup }
         VARIATION        coldStart
             DESCRIPTION  "A coldStart trap is generated on all
                          reboots."
     SUPPORTS             IF-MIB
         INCLUDES         { ifGeneralGroup, ifPacketGroup }
         VARIATION        ifAdminStatus
             SYNTAX       INTEGER { up(1), down(2) }
             DESCRIPTION  "Unable to set test mode on 4BSD."
         VARIATION        ifOperStatus
             SYNTAX       INTEGER { up(1), down(2) }
             DESCRIPTION  "Information limited on 4BSD."
     SUPPORTS             IP-MIB
         INCLUDES         { ipGroup, icmpGroup }
         VARIATION        ipDefaultTTL
             SYNTAX       INTEGER (255..255)
             DESCRIPTION  "Hard-wired on 4BSD."
         VARIATION        ipInAddrErrors
             ACCESS       not-implemented
             DESCRIPTION  "Information not available on 4BSD."
         VARIATION        ipNetToMediaEntry
             CREATION-REQUIRES { ipNetToMediaPhysAddress }
             DESCRIPTION  "Address mappings on 4BSD require
                          both protocol and media addresses."
     SUPPORTS             TCP-MIB
         INCLUDES         { tcpGroup }
         VARIATION        tcpConnState

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             ACCESS       read-only
             DESCRIPTION  "Unable to set this on 4BSD."
     SUPPORTS             UDP-MIB
         INCLUDES         { udpGroup }
     SUPPORTS             EVAL-MIB
         INCLUDES         { functionsGroup, expressionsGroup }
         VARIATION        exprEntry
             CREATION-REQUIRES { evalString, evalStatus }
             DESCRIPTION  "Conceptual row creation is supported."
     ::= { acmeAgents 1 }
 According to this invocation, an agent with a sysORID value of
      { acmeAgents 1 }
 supports objects defined in six MIB modules.
 From SNMPv2-MIB, five conformance groups are supported.
 From IF-MIB, the ifGeneralGroup and ifPacketGroup groups are
 supported.  However, the objects ifAdminStatus and ifOperStatus have
 a restricted syntax.
 From IP-MIB, all objects in the ipGroup and icmpGroup are supported
 except ipInAddrErrors, while ipDefaultTTL has a restricted range, and
 when creating a new instance in the ipNetToMediaTable, the set-
 request must create an instance of ipNetToMediaPhysAddress.
 From TCP-MIB, the tcpGroup is supported except that tcpConnState is
 available only for reading.
 From UDP-MIB, the udpGroup is fully supported.
 From the EVAL-MIB, all the objects contained in the functionsGroup
 and expressionsGroup conformance groups are supported, without
 variation.  In addition, creation of new instances in the expr table
 is supported, and requires both of the objects:  evalString and
 evalStatus, to be assigned a value.

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7. Extending an Information Module

 As experience is gained with a published information module, it may
 be desirable to revise that information module.
 Section 10 of [2] defines the rules for extending an information
 module.  The remainder of this section defines how conformance
 groups, compliance statements, and capabilities statements may be
 extended.

7.1. Conformance Groups

 It may be desirable to revise the definition of a conformance group
 (an OBJECT-GROUP or a NOTIFICATION-GROUP) after experience is gained
 with it.  However, conformance groups can be referenced by compliance
 and/or capabilities definitions.  Therefore, a change to a
 conformance group is not allowed if it has the potential to cause a
 reference to the group's original definition to be different from a
 reference to the updated definition.  Such changes can only be
 accommodated by defining a new conformance group with a new
 descriptor and a new OBJECT IDENTIFIER value.
 The following revisions are allowed:

(1) A STATUS clause value of "current" may be revised as "deprecated"

   or "obsolete".  Similarly, a STATUS clause value of "deprecated"
   may be revised as "obsolete".  When making such a change, the
   DESCRIPTION clause should be updated to explain the rationale.

(2) A REFERENCE clause may be added or updated.

(3) Clarifications and additional information may be included in the

   DESCRIPTION clause.

(4) Any editorial change.

 It is not necessary to change the STATUS value of a conformance group
 when the status of a member of the group is changed.

7.2. Compliance Definitions

 It may be desirable to revise the definition of a compliance
 definition (MODULE-COMPLIANCE) after experience is gained with it.
 However, changes are not allowed if they cause the requirements
 specified by the original definition to be different from the
 requirements of the updated definition.  Such changes can only be
 accommodated by defining a new compliance definition with a new

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 descriptor and a new OBJECT IDENTIFIER value.
 The following revisions are allowed:

(1) A STATUS clause value of "current" may be revised as "deprecated"

   or "obsolete".  Similarly, a STATUS clause value of "deprecated"
   may be revised as "obsolete".  When making such a change, the
   DESCRIPTION clause should be updated to explain the rationale.

(2) A REFERENCE clause may be added or updated.

(3) Clarifications and additional information may be included in the

   DESCRIPTION clause(s).

(4) Any editorial change.

 It is not necessary to change the STATUS value of a compliance
 definition due to a change in the STATUS value of a definition it
 references.

7.3. Capabilities Definitions

 It may be desirable to revise the definition of a capabilities
 definition (AGENT-CAPABILITIES) after experience is gained with it.
 However, changes are not allowed if they cause the capabilities
 specified by the original specification to be different from the
 capabilities of the updated specification.  Such changes can only be
 accommodated by defining a new capabilities definition with a new
 descriptor and a new OBJECT IDENTIFIER value.
 The following revisions are allowed:

(1) A STATUS clause value of "current" may be revised as "obsolete".

   When making such a change, the DESCRIPTION clause should be updated
   to explain the rationale.

(2) A REFERENCE clause may be added or updated.

(3) Clarifications and additional information may be included in the

   DESCRIPTION clause(s).

(4) Any editorial change.

 It is not necessary to change the STATUS value of a capabilities
 definition due to a change in the STATUS value of a definition it
 references.

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8. Security Considerations

 This document defines the means to define conformance requirements
 for implementing on documents describing management information.
 This method of defining conformance requirements has no security
 impact on the Internet.

9. Editors' Addresses

 Keith McCloghrie
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA  95134-1706
 USA
 Phone: +1 408 526 5260
 EMail: kzm@cisco.com
 David Perkins
 SNMPinfo
 3763 Benton Street
 Santa Clara, CA 95051
 USA
 Phone: +1 408 221-8702
 Email: dperkins@snmpinfo.com
 Juergen Schoenwaelder
 TU Braunschweig
 Bueltenweg 74/75
 38106 Braunschweig
 Germany
 Phone: +49 531 391-3283
 EMail: schoenw@ibr.cs.tu-bs.de

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10. References

[1] Information processing systems - Open Systems Interconnection -

   Specification of Abstract Syntax Notation One (ASN.1),
   International Organization for Standardization.  International
   Standard 8824, (December, 1987).

[2] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.

   and S. Waldbusser, "Structure of Management Information Version 2
   (SMIv2)", STD 58, RFC 2578, April 1999.

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

   S. Waldbusser, "Management Information Base for Version 2 of the
   Simple Network Management Protocol (SNMPv2)", RFC 1907, January
   1996.

[4] The 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] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.

   and S. Waldbusser, "Textual Conventions for SMIv2", STD 58,
   RFC 2579, April 1999.

[6] Rose, M. and K. McCloghrie, "Structure and Identification of

   Management Information for TCP/IP-based internets", STD 16, RFC
   1155, May 1990.

[7] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC

   1212, March 1991.

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11. 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."

McCloghrie, et al. Standards Track [Page 29]

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