[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 RFC 1904

Internet Draft     Conformance Statements for SNMPv2          March 1995


              Conformance Statements for Version 2 of the
              Simple Network Management Protocol (SNMPv2)

                             19 March 1995                                |

                    draft-ietf-snmpv2-conf-ds-01.txt                      |


                            Jeffrey D. Case
                          SNMP Research, Inc.
                             case@snmp.com

                            Keith McCloghrie
                          Cisco Systems, Inc.
                             kzm@cisco.com

                            Marshall T. Rose
                      Dover Beach Consulting, Inc.
                         mrose@dbc.mtview.ca.us

                           Steven Waldbusser
                       Carnegie Mellon University
                           waldbusser@cmu.edu






Status of this Memo

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

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

To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).





Expires September 1995                                          [Page 1]


Internet Draft     Conformance Statements for SNMPv2          March 1995


1.  Introduction

A management system contains: several (potentially many) nodes, each
with a processing entity, termed an agent, which has access to
management instrumentation; at least one management station; and, a
management protocol, used to convey management information between the
agents and management stations.  Operations of the protocol are carried
out under an administrative framework which defines authentication,
authorization, access control, and privacy policies.

Management stations execute management applications which monitor and
control managed elements.  Managed elements are devices such as hosts,
routers, terminal servers, etc., which are monitored and controlled via
access to their management information.

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 a subset of OSI's Abstract
Syntax Notation One (ASN.1) [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 Internet-standard Network
Management Framework, as described in RFCs 1155, 1157, and 1212, is
termed the SNMP version 1 framework (SNMPv1).  The current framework is
termed the SNMP version 2 framework (SNMPv2).


1.2.  Change Log

For the 19 March version:                                                 +

-    The many changes adopted by the SNMPv2 Working Group.                +

For the 1 November version:







Expires September 1995                                          [Page 2]


Internet Draft     Conformance Statements for SNMPv2          March 1995


-    recast RFC 1444 into an Internet-Draft,

-    fixed typos,

-    modified the usage examples to refer to the SNMPv2 MIB.













































Expires September 1995                                          [Page 3]


Internet Draft     Conformance Statements for SNMPv2          March 1995


2.  Definitions

SNMPv2-CONF DEFINITIONS ::= BEGIN

-- 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 ::=
                  value(Name ObjectName)

    Status ::=
                  "current"
                | "deprecated"                                            +
                | "obsolete"

    ReferPart ::=
                  "REFERENCE" Text
                | empty

    -- uses the NVT ASCII character set
    Text ::= """" string """"
END













Expires September 1995                                          [Page 4]


Internet Draft     Conformance Statements for SNMPv2          March 1995


-- 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(Name NotificationName)                            |

    Status ::=                                                            |
                  "current"                                               |
                | "deprecated"                                            |
                | "obsolete"                                              |

    ReferPart ::=                                                         |
                  "REFERENCE" Text                                        |
                | empty                                                   |

    -- uses the NVT ASCII character set                                   |
    Text ::= """" string """"                                             |
END                                                                       |

















Expires September 1995                                          [Page 5]


Internet Draft     Conformance Statements for SNMPv2          March 1995


-- 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
                | empty
    Modules ::=
                  Module
                | Modules Module
    Module ::=
                  -- name of module --
                  "MODULE" ModuleName
                  MandatoryPart
                  CompliancePart

    ModuleName ::=
                  modulereference ModuleIdentifier
                -- must not be empty unless contained
                -- in MIB Module
                | empty
    ModuleIdentifier ::=
                  value(ModuleID OBJECT IDENTIFIER)
                | empty

    MandatoryPart ::=
                  "MANDATORY-GROUPS" "{" Groups "}"





Expires September 1995                                          [Page 6]


Internet Draft     Conformance Statements for SNMPv2          March 1995


                | empty

    Groups ::=
                  Group
                | Groups "," Group
    Group ::=
                  value(Group OBJECT IDENTIFIER)

    CompliancePart ::=
                  Compliances
                | empty

    Compliances ::=
                  Compliance
                | Compliances Compliance
    Compliance ::=
                  ComplianceGroup
                | Object

    ComplianceGroup ::=
                  "GROUP" value(Name OBJECT IDENTIFIER)
                  "DESCRIPTION" Text

    Object ::=
                  "OBJECT" value(Name ObjectName)
                  SyntaxPart
                  WriteSyntaxPart
                  AccessPart
                  "DESCRIPTION" Text

    -- must be a refinement for object's SYNTAX clause
    SyntaxPart ::=
                  "SYNTAX" type(SYNTAX)
                | empty

    -- must be a refinement for object's SYNTAX clause
    WriteSyntaxPart ::=
                  "WRITE-SYNTAX" type(WriteSYNTAX)
                | empty

    AccessPart ::=
                  "MIN-ACCESS" Access
                | empty
    Access ::=
                  "not-accessible"





Expires September 1995                                          [Page 7]


Internet Draft     Conformance Statements for SNMPv2          March 1995


                | "accessible-for-notify"                                 +
                | "read-only"
                | "read-write"
                | "read-create"

    -- uses the NVT ASCII character set
    Text ::= """" string """"
END










































Expires September 1995                                          [Page 8]


Internet Draft     Conformance Statements for SNMPv2          March 1995


-- 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 ::=
                  identifier ModuleIdentifier
    ModuleIdentifier ::=
                  value(ModuleID OBJECT IDENTIFIER)
                | empty

    Groups ::=
                  Group
                | Groups "," Group
    Group ::=
                  value(Name OBJECT IDENTIFIER)





Expires September 1995                                          [Page 9]


Internet Draft     Conformance Statements for SNMPv2          March 1995


    VariationPart ::=
                  Variations
                | empty
    Variations ::=
                  Variation
                | Variations Variation

    Variation ::=
                  ObjectVariation                                         +
                | NotificationVariation                                   +

    NotificationVariation ::=                                             +
                  "VARIATION" value(Name NotificationName)                +
                  "DESCRIPTION" Text                                      +

    ObjectVariation ::=                                                   +
                  "VARIATION" value(Name ObjectName)
                  SyntaxPart
                  WriteSyntaxPart
                  AccessPart
                  CreationPart
                  DefValPart
                  "DESCRIPTION" Text

    -- must be a refinement for object's SYNTAX clause
    SyntaxPart ::=
                  "SYNTAX" type(SYNTAX)
                | empty

    -- must be a refinement for object's SYNTAX clause
    WriteSyntaxPart ::=
                  "WRITE-SYNTAX" type(WriteSYNTAX)
                | empty

    AccessPart ::=
                  "ACCESS" Access
                | empty

    Access ::=
                  "not-implemented"
                | "accessible-for-notify"                                 +
                | "read-only"
                | "read-write"
                | "read-create"
                -- following is for backward-compatibility only





Expires September 1995                                         [Page 10]


Internet Draft     Conformance Statements for SNMPv2          March 1995


                | "write-only"

    CreationPart ::=
                  "CREATION-REQUIRES" "{" Cells "}"
                | empty

    Cells ::=
                  Cell
                | Cells "," Cell

    Cell ::=
                  value(Cell ObjectName)

    DefValPart ::=
                  "DEFVAL" "{" value(Defval ObjectSyntax) "}"
                | empty

    -- uses the NVT ASCII character set
    Text ::= """" string """"
END


END



























Expires September 1995                                         [Page 11]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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, a SNMPv2 entity acting in an agent role 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, a SNMPv2 entity must accordingly be
able to reasonably influence the underlying managed entity.  If a SNMPv2
entity acting in an agent role can not implement an object, the
management protocol provides for the SNMPv2 entity to return an
exception or error, e.g, noSuchObject [4].  Under no circumstances shall
a SNMPv2 entity 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].


3.1.  Mapping of the OBJECTS clause

The OBJECTS clause, which must be present, is used to name each object
contained in the conformance group.  Each of the named 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 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.                                                    +


3.2.  Mapping of the STATUS clause

The STATUS clause, which must be present, indicates whether this
definition is current or historic.

The values "current", and "obsolete" are self-explanatory.  The           +
"deprecated" value indicates that the group is obsolete, but that an      +
implementor may wish to support it to foster interoperability with older  +
implementations.                                                          +





Expires September 1995                                         [Page 12]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 a group  defined in some other information module.
This is useful when de-osifying a MIB module produced by some other
organization.


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.





























Expires September 1995                                         [Page 13]


Internet Draft     Conformance Statements for SNMPv2          March 1995


3.6.  Usage Example

The SNMP Statistics Group [3] is described:

snmpStatsGroup OBJECT-GROUP
    OBJECTS { snmpStatsPackets, snmpStats30Something,
              snmpStatsEncodingErrors,
              snmpStatsUnknownDstParties,
              snmpStatsDstPartyMismatches,
              snmpStatsUnknownSrcParties, snmpStatsBadAuths,
              snmpStatsNotInLifetimes,
              snmpStatsWrongDigestValues,
              snmpStatsUnknownContexts,
              snmpStatsBadOperations,
              snmpStatsSilentDrops }
    STATUS  current
    DESCRIPTION
            "A collection of objects providing basic instrumentation of
            the SNMPv2 entity."
    ::= { snmpMIBGroups 1 }

According to this invocation, the conformance group named

     { snmpMIBGroups 1 }

contains 12 objects.
























Expires September 1995                                         [Page 14]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 name each     +
notification contained in the conformance group.  Each of the named       +
notifications must be defined in the same information module as the       +
NOTIFICATION-GROUP macro appears.                                         +


4.2.  Mapping of the STATUS clause                                        +

The STATUS clause, which must be present, indicates whether this          +
definition is current or historic.                                        +

The values "current", and "obsolete" are self-explanatory.  The           +
"deprecated" value indicates that the group is obsolete, but that an      +
implementor may wish to support it to foster interoperability with older  +
implementations.                                                          +


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 a group defined in some other information module.      +
This is useful when de-osifying a MIB module produced by some other       +
organization.                                                             +







Expires September 1995                                         [Page 15]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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.                                                            +













































Expires September 1995                                         [Page 16]


Internet Draft     Conformance Statements for SNMPv2          March 1995


4.6.  Usage Example                                                       +

The SNMP Basic Notifications Group [3] is described:                      +


snmpBasicNotificationsGroup NOTIFICATION-GROUP                            +
    NOTIFICATIONS { coldStart, authenticationFailure }                    +
    STATUS        current                                                 +
    DESCRIPTION                                                           +
            "The two notifications which an SNMPv2 entity is required to  +
            implement."                                                   +
    ::= { snmpNotificationGroups 1 }                                      +

According to this invocation, the conformance group named                 +

     { snmpNotificationGroups 1 }                                         +

contains 2 notifications.                                                 +
































Expires September 1995                                         [Page 17]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 values "current", and "obsolete" are self-explanatory.  The           |
"deprecated" value indicates that the specification is obsolete,          |
but that an implementor may wish to support that object to foster
interoperability with older implementations.


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.


5.3.  Mapping of the REFERENCE clause

The REFERENCE clause, which need not be present, contains a textual
cross-reference to a compliance statement defined in some other
information module.


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





Expires September 1995                                         [Page 18]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 a SNMPv2 entity
acting in an agent role claims compliance to the MIB module, then it      |
must implement each and every object and notification within each         |
conformance group listed.                                                 |
That is, if a SNMPv2 entity returns a noSuchObject exception in response
to a management protocol get operation [4] for any object within any
mandatory conformance group for every MIB view, or if the SNMPv2 entity   +
cannot generate each notification listed in any conformance group under   +
the appropriate circumstances,                                            +
then that SNMPv2 entity 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 or unconditionally optional for compliance to
the MIB module.  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.


5.4.3.  Mapping of the OBJECT clause

The OBJECT clause, which need not be present,                             |
is repeatedly used to name each MIB object for which compliance has a
refined requirement with respect to the MIB module definition.  The MIB





Expires September 1995                                         [Page 19]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 where     +
the object is imported from 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 are: conceptual tables and rows,
auxiliary objects, and objects with the syntax of Counter32, Counter64,
or certain types of textual conventions (e.g., RowStatus [5]).  A MIN-
ACCESS clause should not be present for such objects.





Expires September 1995                                         [Page 20]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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.


5.4.3.4.  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.






























Expires September 1995                                         [Page 21]


Internet Draft     Conformance Statements for SNMPv2          March 1995


5.6.  Usage Example

The compliance statement contained in SNMPv2-MIB [3] is:

snmpMIBCompliance MODULE-COMPLIANCE
    STATUS  current
    DESCRIPTION
            "The compliance statement for SNMPv2 entities which
            implement the SNMPv2 MIB."
    MODULE  -- compliance to the containing MIB module
        MANDATORY-GROUPS { systemGroup,
                           snmpStatsGroup, snmpORGroup,
                           snmpTrapGroup, snmpSetGroup,                   |
                           snmpBasicNotificationsGroup }                  |

        GROUP   snmpV1Group
        DESCRIPTION
            "The snmpV1 group is mandatory only for those
             SNMPv2 entities which also implement SNMPv1."
::= { snmpMIBCompliances 1 }

According to this invocation, to claim alignment with the compliance
statement named

     { snmpMIBCompliances 1 }

a system must implement the SNMPv2-MIB's systemGroup, snmpStatsGroup,
snmpORGroup, snmpTrapGroup, and snmpSetGroup object conformance groups,   |
as well as the snmpBasicNotificationsGroup notifications group.           |
Furthermore, if the SNMPv2 entity also implements SNMPv1, then it must
also support the SNMPv1Group group, if compliance is to be claimed.



















Expires September 1995                                         [Page 22]


Internet Draft     Conformance Statements for SNMPv2          March 1995


6.  Mapping of the AGENT-CAPABILITIES macro

The AGENT-CAPABILITIES macro is used to convey the capabilities present
in a SNMPv2 entity acting in an agent role.  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 a SNMPv2 entity acting in an agent role claims to
implement a group, then it must implement each and every object within
that group.  Of course, for whatever reason, a SNMPv2 entity might
implement only a subset of the groups within a MIB module.  In addition,
the definition of some MIB objects 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        |
snmpORID [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 snmpORID.  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 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 agent.







Expires September 1995                                         [Page 23]


Internet Draft     Conformance Statements for SNMPv2          March 1995


6.2.  Mapping of the STATUS clause

The STATUS clause, which must be present, indicates whether this
definition is current ("current") or historic ("obsolete").


6.3.  Mapping of the DESCRIPTION clause

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


6.4.  Mapping of the REFERENCE clause

The REFERENCE clause, which need not be present, contains a textual
cross-reference to a capability statement defined in some other
information module.


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 well.


6.5.1.  Mapping of the INCLUDES clause

The INCLUDES clause, which must be present for each 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 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.





Expires September 1995                                         [Page 24]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 where  +
the object is imported from is redundant, and is not 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.


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 named
in the correspondent VARIATION clause.

The value "not-implemented" indicates the agent does not implement the
object, 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".










Expires September 1995                                         [Page 25]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 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
refined 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.                     |










Expires September 1995                                         [Page 26]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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 snmpORID [3] for which               |
this capabilities statement is valid.













































Expires September 1995                                         [Page 27]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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,                        |
                         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





Expires September 1995                                         [Page 28]


Internet Draft     Conformance Statements for SNMPv2          March 1995


        INCLUDES         { tcpGroup }
        VARIATION        tcpConnState
            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 }
            DESCRIPTION "Conceptual row creation supported"

    ::= { acmeAgents 1 }


According to this invocation, an agent with a snmpORID value of           |

     { acmeAgents 1 }

supports six MIB modules.

From SNMPv2-MIB, the system and snmp conformance group 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 atPhysAddress.

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.








Expires September 1995                                         [Page 29]


Internet Draft     Conformance Statements for SNMPv2          March 1995


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

If any non-editorial change is made to any clause of an object group
then the OBJECT IDENTIFIER value associated with that object group must
also be changed, along with its associated descriptor.


7.2.  Compliance Definitions

If any non-editorial change is made to any clause of a compliance
definition, then the OBJECT IDENTIFIER value associated with that
compliance definition must also be changed, along with its associated
descriptor.


7.3.  Capabilities Definitions

If any non-editorial change is made to any clause of a capabilities
definition, then the OBJECT IDENTIFIER value associated with that
capabilities definition must also be changed, along with its associated
descriptor.



















Expires September 1995                                         [Page 30]


Internet Draft     Conformance Statements for SNMPv2          March 1995


8.  Acknowledgements

The authors wish to acknowledge the contributions of the SNMPv2 Working
Group in general.  In particular, the following individuals

     Dave Arneson (Cabletron),
     Uri Blumenthal (IBM),
     Doug Book (Chipcom),
     Maria Greene (Ascom Timeplex),
     Deirdre Kostik (Bellcore),
     Dave Harrington (Cabletron),
     Jeff Johnson (Cisco Systems),
     Brian O'Keefe (Hewlett Packard),
     Dave Perkins (Bay Networks),
     Randy Presuhn (Peer Networks),
     Shawn Routhier (Epilogue),
     Bob Stewart (Cisco Systems),
     Kaj Tesink (Bellcore).

deserve special thanks for their contributions.


9.  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]  Case, J., McCloghrie, K., Rose, M., and Waldbusser, S., "Structure
     of Management Information for Version 2 of the Simple Network
     Management Protocol (SNMPv2)", Internet Draft, SNMP Research, Inc.,
     Cisco Systems, Dover Beach Consulting, Inc., Carnegie Mellon
     University, March 1995.                                              |

[3]  Case, J., McCloghrie, K., Rose, M., and Waldbusser, S., "Management
     Information Base for Version 2 of the Simple Network Management
     Protocol (SNMPv2)", Internet Draft, SNMP Research, Inc., Cisco
     Systems, Dover Beach Consulting, Inc., Carnegie Mellon University,   |
     March 1995.                                                          |

[4]  Case, J., McCloghrie, K., Rose, M., and Waldbusser, S., "Protocol
     Operations for Version 2 of the Simple Network Management Protocol
     (SNMPv2)", Internet Draft, SNMP Research, Inc., Cisco Systems,
     Dover Beach Consulting, Inc., Carnegie Mellon University, March      |





Expires September 1995                                         [Page 31]


Internet Draft     Conformance Statements for SNMPv2          March 1995


     1995.                                                                |

[5]  Case, J., McCloghrie, K., Rose, M., and Waldbusser, S., "Textual
     Conventions for Version 2 of the the Simple Network Management
     Protocol (SNMPv2)", Internet Draft, SNMP Research, Inc., Cisco
     Systems, Dover Beach Consulting, Inc., Carnegie Mellon University,   |
     March 1995.                                                          |

[6]  Rose, M., and McCloghrie, K., "Structure and Identification of
     Management Information for TCP/IP-based internets", STD 16, RFC
     1155, May 1990.

[7]  Rose, M., and McCloghrie, K., "Concise MIB Definitions", STD 16,
     RFC 1212, March 1991.




































Expires September 1995                                         [Page 32]


Internet Draft     Conformance Statements for SNMPv2          March 1995


10.  Security Considerations

Security issues are not discussed in this memo.


11.  Authors' Addresses

     Jeffrey D. Case
     SNMP Research, Inc.
     3001 Kimberlin Heights Rd.
     Knoxville, TN  37920-9716
     US

     Phone: +1 615 573 1434
     Email: case@snmp.com


     Keith McCloghrie
     Cisco Systems, Inc.
     170 West Tasman Drive,
     San Jose CA 95134-1706.

     Phone: +1 408 526 5260
     Email: kzm@cisco.com


     Marshall T. Rose
     Dover Beach Consulting, Inc.
     420 Whisman Court
     Mountain View, CA  94043-2186
     US

     Phone: +1 415 968 1052
     Email: mrose@dbc.mtview.ca.us

     Steven Waldbusser
     Carnegie Mellon University
     5000 Forbes Ave
     Pittsburgh, PA  15213
     US

     Phone: +1 412 268 6628
     Email: waldbusser@cmu.edu







Expires September 1995                                         [Page 33]


Internet Draft     Conformance Statements for SNMPv2          March 1995


Table of Contents


1 Introduction ....................................................    2
1.1 A Note on Terminology .........................................    2
1.2 Change Log ....................................................    2
2 Definitions .....................................................    4
2.1 The OBJECT-GROUP macro ........................................    4
2.2 The NOTIFICATION-GROUP macro ..................................    5
2.3 The MODULE-COMPLIANCE macro ...................................    6
2.4 The AGENT-CAPABILITIES macro ..................................    9
3 Mapping of the OBJECT-GROUP macro ...............................   12
3.1 Mapping of the OBJECTS clause .................................   12
3.2 Mapping of the STATUS clause ..................................   12
3.3 Mapping of the DESCRIPTION clause .............................   13
3.4 Mapping of the REFERENCE clause ...............................   13
3.5 Mapping of the OBJECT-GROUP value .............................   13
3.6 Usage Example .................................................   14
4 Mapping of the NOTIFICATION-GROUP macro .........................   15
4.1 Mapping of the NOTIFICATIONS clause ...........................   15
4.2 Mapping of the STATUS clause ..................................   15
4.3 Mapping of the DESCRIPTION clause .............................   15
4.4 Mapping of the REFERENCE clause ...............................   15
4.5 Mapping of the NOTIFICATION-GROUP value .......................   16
4.6 Usage Example .................................................   17
5 Mapping of the MODULE-COMPLIANCE macro ..........................   18
5.1 Mapping of the STATUS clause ..................................   18
5.2 Mapping of the DESCRIPTION clause .............................   18
5.3 Mapping of the REFERENCE clause ...............................   18
5.4 Mapping of the MODULE clause ..................................   18
5.4.1 Mapping of the MANDATORY-GROUPS clause ......................   19
5.4.2 Mapping of the GROUP clause .................................   19
5.4.3 Mapping of the OBJECT clause ................................   19
5.4.3.1 Mapping of the SYNTAX clause ..............................   20
5.4.3.2 Mapping of the WRITE-SYNTAX clause ........................   20
5.4.3.3 Mapping of the MIN-ACCESS clause ..........................   20
5.4.3.4 Mapping of the DESCRIPTION clause .........................   21
5.5 Mapping of the MODULE-COMPLIANCE value ........................   21
5.6 Usage Example .................................................   22
6 Mapping of the AGENT-CAPABILITIES macro .........................   23
6.1 Mapping of the PRODUCT-RELEASE clause .........................   23
6.2 Mapping of the STATUS clause ..................................   24
6.3 Mapping of the DESCRIPTION clause .............................   24
6.4 Mapping of the REFERENCE clause ...............................   24
6.5 Mapping of the SUPPORTS clause ................................   24





Expires September 1995                                         [Page 34]


Internet Draft     Conformance Statements for SNMPv2          March 1995


6.5.1 Mapping of the INCLUDES clause ..............................   24
6.5.2 Mapping of the VARIATION clause .............................   24
6.5.2.1 Mapping of the SYNTAX clause ..............................   25
6.5.2.2 Mapping of the WRITE-SYNTAX clause ........................   25
6.5.2.3 Mapping of the ACCESS clause ..............................   25
6.5.2.4 Mapping of the CREATION-REQUIRES clause ...................   26
6.5.2.5 Mapping of the DEFVAL clause ..............................   26
6.5.2.6 Mapping of the DESCRIPTION clause .........................   26
6.6 Mapping of the AGENT-CAPABILITIES value .......................   27
6.7 Usage Example .................................................   28
7 Extending an Information Module .................................   30
7.1 Conformance Groups ............................................   30
7.2 Compliance Definitions ........................................   30
7.3 Capabilities Definitions ......................................   30
8 Acknowledgements ................................................   31
9 References ......................................................   31
10 Security Considerations ........................................   33
11 Authors' Addresses .............................................   33
































Expires September 1995                                         [Page 35]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/