Network Working Group J. Case
Request for Comments: 1444 SNMP Research, Inc.
K. McCloghrie
Hughes LAN Systems
M. Rose
Dover Beach Consulting, Inc.
S. Waldbusser
Carnegie Mellon University
April 1993
Conformance Statements
for version 2 of the
Simple Network Management Protocol (SNMPv2)
Status of this Memo
This RFC specifes an IAB standards track protocol for the
Internet community, and requests discussion and suggestions
for improvements. Please refer to the current edition of the
"IAB Official Protocol Standards" for the standardization
state and status of this protocol. Distribution of this memo
is unlimited.
Table of Contents
1 Introduction .......................................... 2
1.1 A Note on Terminology ............................... 2
2 Definitions ........................................... 3
3.1 The OBJECT-GROUP macro .............................. 3
3.2 The MODULE-COMPLIANCE macro ......................... 4
3.3 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 ........................ 10
3.3 Mapping of the DESCRIPTION clause ................... 10
3.4 Mapping of the REFERENCE clause ..................... 11
3.5 Mapping of the OBJECT-GROUP value ................... 11
3.6 Usage Example ....................................... 12
4 Mapping of the MODULE-COMPLIANCE macro ................ 13
4.1 Mapping of the STATUS clause ........................ 13
4.2 Mapping of the DESCRIPTION clause ................... 13
4.3 Mapping of the REFERENCE clause ..................... 13
4.4 Mapping of the MODULE clause ........................ 13
4.4.1 Mapping of the MANDATORY-GROUPS clause ............ 14
4.4.2 Mapping of the GROUP clause ....................... 14
4.4.3 Mapping of the OBJECT clause ...................... 14
Case, McCloghrie, Rose & Waldbusser [Page i]
RFC 1444 Conformance Statements for SNMPv2 April 1993
4.4.3.1 Mapping of the SYNTAX clause .................... 15
4.4.3.2 Mapping of the WRITE-SYNTAX clause .............. 15
4.4.3.3 Mapping of the MIN-ACCESS clause ................ 15
4.4.3.4 Mapping of the DESCRIPTION clause ............... 16
4.5 Mapping of the MODULE-COMPLIANCE value .............. 16
4.6 Usage Example ....................................... 17
5 Mapping of the AGENT-CAPABILITIES macro ............... 19
5.1 Mapping of the PRODUCT-RELEASE clause ............... 20
5.2 Mapping of the STATUS clause ........................ 20
5.3 Mapping of the DESCRIPTION clause ................... 20
5.4 Mapping of the REFERENCE clause ..................... 20
5.5 Mapping of the SUPPORTS clause ...................... 20
5.5.1 Mapping of the INCLUDES clause .................... 21
5.5.2 Mapping of the VARIATION clause ................... 21
5.5.2.1 Mapping of the SYNTAX clause .................... 21
5.5.2.2 Mapping of the WRITE-SYNTAX clause .............. 21
5.5.2.3 Mapping of the ACCESS clause .................... 22
5.5.2.4 Mapping of the CREATION-REQUIRES clause ......... 22
5.5.2.5 Mapping of the DEFVAL clause .................... 23
5.5.2.6 Mapping of the DESCRIPTION clause ............... 23
5.6 Mapping of the AGENT-CAPABILITIES value ............. 23
5.7 Usage Example ....................................... 24
6 Extending an Information Module ....................... 26
6.1 Conformance Groups .................................. 26
6.2 Compliance Definitions .............................. 26
6.3 Capabilities Definitions ............................ 26
7 Acknowledgements ...................................... 27
8 References ............................................ 31
9 Security Considerations ............................... 32
10 Authors' Addresses ................................... 32
Case, McCloghrie, Rose & Waldbusser [Page 1]
RFC 1444 Conformance Statements for SNMPv2 April 1993
1. Introduction
A network 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 both authentication and
authorization policies.
Network management stations execute management applications
which monitor and control network elements. Network elements
are devices such as hosts, routers, terminal servers, etc.,
which are monitored and controlled through 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).
Case, McCloghrie, Rose & Waldbusser [Page 2]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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"
| "obsolete"
ReferPart ::=
"REFERENCE" Text
| empty
-- uses the NVT ASCII character set
Text ::= """" string """"
END
Case, McCloghrie, Rose & Waldbusser [Page 3]
RFC 1444 Conformance Statements for SNMPv2 April 1993
-- definitions for compliance statements
MODULE-COMPLIANCE MACRO ::=
BEGIN
TYPE NOTATION ::=
"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 --
"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 "}"
| empty
Case, McCloghrie, Rose & Waldbusser [Page 4]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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"
| "read-only"
| "read-write"
Case, McCloghrie, Rose & Waldbusser [Page 5]
RFC 1444 Conformance Statements for SNMPv2 April 1993
| "read-create"
-- uses the NVT ASCII character set
Text ::= """" string """"
END
Case, McCloghrie, Rose & Waldbusser [Page 6]
RFC 1444 Conformance Statements for SNMPv2 April 1993
-- definitions for capabilities statements
AGENT-CAPABILITIES MACRO ::=
BEGIN
TYPE NOTATION ::=
"PRODUCT-RELEASE" Text
"STATUS" Status
"DESCRIPTION" Text
ReferPart
ModulePart
VALUE NOTATION ::=
-- agent's sysObjectID [3] or snmpORID [4]
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 ::=
Case, McCloghrie, Rose & Waldbusser [Page 7]
RFC 1444 Conformance Statements for SNMPv2 April 1993
value(Name OBJECT IDENTIFIER)
VariationPart ::=
Variations
| empty
Variations ::=
Variation
| Variations Variation
Variation ::=
"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"
| "read-only"
| "read-write"
| "read-create"
-- following is for backward-compatibility only
| "write-only"
CreationPart ::=
"CREATION-REQUIRES" "{" Cells "}"
| empty
Cells ::=
Case, McCloghrie, Rose & Waldbusser [Page 8]
RFC 1444 Conformance Statements for SNMPv2 April 1993
Cell
| Cells "," Cell
Cell ::=
value(Cell ObjectName)
DefValPart ::=
"DEFVAL" "{" value(Defval ObjectSyntax) "}"
| empty
-- uses the NVT ASCII character set
Text ::= """" string """"
END
END
Case, McCloghrie, Rose & Waldbusser [Page 9]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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 [6]. 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 [6].
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 "read-only", "read-write", or "read-create".
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.
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
Case, McCloghrie, Rose & Waldbusser [Page 10]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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.
Case, McCloghrie, Rose & Waldbusser [Page 11]
RFC 1444 Conformance Statements for SNMPv2 April 1993
3.6. Usage Example
Consider how the system group from MIB-II [3] might be
described:
systemGroup OBJECT-GROUP
OBJECTS { sysDescr, sysObjectID, sysUpTime,
sysContact, sysName, sysLocation,
sysServices }
STATUS current
DESCRIPTION
"The system group defines objects which are common
to all managed systems."
::= { mibIIGroups 1 }
According to this invocation, the conformance group named
{ mibIIGroups 1 }
contains 7 objects.
Case, McCloghrie, Rose & Waldbusser [Page 12]
RFC 1444 Conformance Statements for SNMPv2 April 1993
4. 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.
4.1. 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 that object is obsolete,
but that an implementor may wish to support that object to
foster interoperability with older implementations.
4.2. 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.
4.3. 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.
4.4. 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
Case, McCloghrie, Rose & Waldbusser [Page 13]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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.
4.4.1. Mapping of the MANDATORY-GROUPS clause
The MANDATORY-GROUPS clause, which need not be present, names
the one or more 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
within each conformance group listed. That is, if a SNMPv2
entity returns a noSuchObject exception in response to a
management protocol get operation [5] for any object within
any mandatory conformance group for every MIB view, then that
SNMPv2 entity is not a conformant implementation of the MIB
module.
4.4.2. Mapping of the GROUP clause
The GROUP clause which need not be present, is repeatedly used
to name each MIB group which is conditionally mandatory or
unconditionally optional for compliance to the MIB module. A
MIB 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 MIB group which is named in neither a MANDATORY-GROUPS
clause nor a GROUP clause, is unconditionally optional for
compliance to the MIB module.
4.4.3. 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
Case, McCloghrie, Rose & Waldbusser [Page 14]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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.
4.4.3.1. 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 10 of [2] for more information on refined
syntax.
4.4.3.2. 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 10 of [2] for more information on refined
syntax.
4.4.3.3. 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
Case, McCloghrie, Rose & Waldbusser [Page 15]
RFC 1444 Conformance Statements for SNMPv2 April 1993
textual conventions (e.g., RowStatus [6]). A MIN-ACCESS
clause should not be present for such 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.
4.4.3.4. 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.
4.5. 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.
Case, McCloghrie, Rose & Waldbusser [Page 16]
RFC 1444 Conformance Statements for SNMPv2 April 1993
4.6. Usage Example
Consider how a compliance statement might be included at the
end of the MIB-II document [3], assuming that conformance
groups were defined therein:
mibIICompliances
OBJECT IDENTIFIER ::= { mibIIConformance 1 }
mibIIGroups OBJECT IDENTIFIER ::= { mibIIConformance 2 }
mibIICompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities
residing on systems which implement the Internet
suite of protocols."
MODULE -- compliance to the containing MIB module
MANDATORY-GROUPS { systemGroup, snmpGroup }
GROUP interfacesGroup
DESCRIPTION
"The interfaces group is mandatory for systems
with network interfaces."
GROUP ipGroup
DESCRIPTION
"The ip group is mandatory for systems which
implement IP."
GROUP icmpGroup
DESCRIPTION
"The icmp group is mandatory for systems which
implement ICMP."
GROUP tcpGroup
DESCRIPTION
"The tcp group is mandatory for systems which
implement TCP."
OBJECT tcpConnState
MIN-ACCESS read-only
DESCRIPTION
"A compliant system need not allow
write-access to this object."
GROUP udpGroup
Case, McCloghrie, Rose & Waldbusser [Page 17]
RFC 1444 Conformance Statements for SNMPv2 April 1993
DESCRIPTION
"The udp group is mandatory for systems which
implement UDP."
GROUP egpGroup
DESCRIPTION
"The egp group is mandatory for systems which
implement EGP."
::= { mibIICompliances 1 }
According to this invocation, to claim alignment with the
compliance statement named
{ mibIICompliances 1 }
a system must implement RFC1213's systemGroup and snmpGroup
conformance groups. If the system implements any network
interfaces, then RFC1213's interfacesGroup conformance group
must be implemented. Further, if the system implements any of
the IP, ICMP, TCP, UDP, or EGP protocols, then the
correspondent conformance group in RFC1213 must be
implemented, if compliance is to be claimed. Finally,
although RFC1213 specifies that it makes "protocol sense" for
the tcpConnState object to be writable, this specification
allows the system to permit only read-only access and still
claim compliance.
Case, McCloghrie, Rose & Waldbusser [Page 18]
RFC 1444 Conformance Statements for SNMPv2 April 1993
5. 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 sysObjectID [3] associated
with the agent, or to the value of an instance of the snmpORID
object in the snmpORTable [4]. 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 the agent's sysObjectID [3]. Based on
this, it consults the database. If an entry is found, then
the management application can optimize its behavior
accordingly.
Note that this binding to sysObjectID may not always suffice
to define all MIB objects to which an agent can provide
access. In particular, this situation occurs where the agent
dynamically learns of the objects it supports. In these
cases, the snmpORID column of snmpORTable [4] contains
information which should be used in addition to sysObjectID.
Case, McCloghrie, Rose & Waldbusser [Page 19]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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.
5.1. 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.
5.2. 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 that object is obsolete,
but that an implementor may wish to support that object to
foster interoperability with older implementations.
5.3. Mapping of the DESCRIPTION clause
The DESCRIPTION clause, which must be present, contains a
textual description of this agent.
5.4. 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.
5.5. 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.
Case, McCloghrie, Rose & Waldbusser [Page 20]
RFC 1444 Conformance Statements for SNMPv2 April 1993
5.5.1. 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 SUPPORT clause, which the agent claims to implement.
5.5.2. Mapping of the VARIATION clause
The VARIATION clause, which need not be present, is repeatedly
used to name each MIB object 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.
5.5.2.1. 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 10 of [2] for more information on refined
syntax.
5.5.2.2. 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 10 of [2] for more information on refined
syntax.
Case, McCloghrie, Rose & Waldbusser [Page 21]
RFC 1444 Conformance Statements for SNMPv2 April 1993
5.5.2.3. 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".
5.5.2.4. 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 [6].)
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 [7,8]), 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".
Case, McCloghrie, Rose & Waldbusser [Page 22]
RFC 1444 Conformance Statements for SNMPv2 April 1993
5.5.2.5. 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.
5.5.2.6. 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.
5.6. 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 sysObjectID [3]
or snmpORID [4] for which this capabilities statement is
valid.
Case, McCloghrie, Rose & Waldbusser [Page 23]
RFC 1444 Conformance Statements for SNMPv2 April 1993
5.7. 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 RFC1213-MIB
INCLUDES { systemGroup, interfacesGroup,
atGroup, ipGroup, icmpGroup,
tcpGroup, udpGroup, snmpGroup }
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"
VARIATION atEntry
CREATION-REQUIRES { atPhysAddress }
DESCRIPTION "Address mappings on 4BSD require
both protocol and media addresses"
VARIATION ipDefaultTTL
SYNTAX INTEGER (255..255)
DESCRIPTION "Hard-wired on 4BSD"
VARIATION ipInAddrErrors
ACCESS not-implemented
DESCRIPTION "Information not available on 4BSD"
VARIATION ipRouteType
SYNTAX INTEGER { direct(3), indirect(4) }
WRITE-SYNTAX INTEGER { invalid(2), direct(3),
indirect(4) }
DESCRIPTION "Information limited on 4BSD"
VARIATION tcpConnState
ACCESS read-only
DESCRIPTION "Unable to set this on 4BSD"
Case, McCloghrie, Rose & Waldbusser [Page 24]
RFC 1444 Conformance Statements for SNMPv2 April 1993
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 sysObjectID (or
snmpORID) value of
{ acmeAgents 1 }
supports two MIB modules.
From MIB-II, all conformance groups except the egpGroup
conformance group are supported. However, the object
ipInAddrErrors is not implemented, whilst the objects
ifAdminStatus
ifOperStatus
ipDefaultTTL
ipRouteType
have a restricted syntax, and the object
tcpConnState
is available only for reading. Note that in the case of the
object ipRouteType the set of values which may be read is
different than the set of values which may be written.
Finally, when creating a new instance in the atTable, the
set-request must create an instance of atPhysAddress.
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.
Case, McCloghrie, Rose & Waldbusser [Page 25]
RFC 1444 Conformance Statements for SNMPv2 April 1993
6. 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.
6.1. 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.
6.2. 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.
6.3. 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.
Case, McCloghrie, Rose & Waldbusser [Page 26]
RFC 1444 Conformance Statements for SNMPv2 April 1993
7. Acknowledgements
The section on compliance statements is based, in part, on a
conversation with James R. Davin in December, 1990.
The section on capabilities statements is based, in part, on
RFC 1303.
Finally, the comments of the SNMP version 2 working group are
gratefully acknowledged:
Beth Adams, Network Management Forum
Steve Alexander, INTERACTIVE Systems Corporation
David Arneson, Cabletron Systems
Toshiya Asaba
Fred Baker, ACC
Jim Barnes, Xylogics, Inc.
Brian Bataille
Andy Bierman, SynOptics Communications, Inc.
Uri Blumenthal, IBM Corporation
Fred Bohle, Interlink
Jack Brown
Theodore Brunner, Bellcore
Stephen F. Bush, GE Information Services
Jeffrey D. Case, University of Tennessee, Knoxville
John Chang, IBM Corporation
Szusin Chen, Sun Microsystems
Robert Ching
Chris Chiotasso, Ungermann-Bass
Bobby A. Clay, NASA/Boeing
John Cooke, Chipcom
Tracy Cox, Bellcore
Juan Cruz, Datability, Inc.
David Cullerot, Cabletron Systems
Cathy Cunningham, Microcom
James R. (Chuck) Davin, Bellcore
Michael Davis, Clearpoint
Mike Davison, FiberCom
Cynthia DellaTorre, MITRE
Taso N. Devetzis, Bellcore
Manual Diaz, DAVID Systems, Inc.
Jon Dreyer, Sun Microsystems
David Engel, Optical Data Systems
Mike Erlinger, Lexcel
Roger Fajman, NIH
Case, McCloghrie, Rose & Waldbusser [Page 27]
RFC 1444 Conformance Statements for SNMPv2 April 1993
Daniel Fauvarque, Sun Microsystems
Karen Frisa, CMU
Shari Galitzer, MITRE
Shawn Gallagher, Digital Equipment Corporation
Richard Graveman, Bellcore
Maria Greene, Xyplex, Inc.
Michel Guittet, Apple
Robert Gutierrez, NASA
Bill Hagerty, Cabletron Systems
Gary W. Haney, Martin Marietta Energy Systems
Patrick Hanil, Nokia Telecommunications
Matt Hecht, SNMP Research, Inc.
Edward A. Heiner, Jr., Synernetics Inc.
Susan E. Hicks, Martin Marietta Energy Systems
Geral Holzhauer, Apple
John Hopprich, DAVID Systems, Inc.
Jeff Hughes, Hewlett-Packard
Robin Iddon, Axon Networks, Inc.
David Itusak
Kevin M. Jackson, Concord Communications, Inc.
Ole J. Jacobsen, Interop Company
Ronald Jacoby, Silicon Graphics, Inc.
Satish Joshi, SynOptics Communications, Inc.
Frank Kastenholz, FTP Software
Mark Kepke, Hewlett-Packard
Ken Key, SNMP Research, Inc.
Zbiginew Kielczewski, Eicon
Jongyeoi Kim
Andrew Knutsen, The Santa Cruz Operation
Michael L. Kornegay, VisiSoft
Deirdre C. Kostik, Bellcore
Cheryl Krupczak, Georgia Tech
Mark S. Lewis, Telebit
David Lin
David Lindemulder, AT&T/NCR
Ben Lisowski, Sprint
David Liu, Bell-Northern Research
John Lunny, The Wollongong Group
Robert C. Lushbaugh Martin, Marietta Energy Systems
Michael Luufer, BBN
Carl Madison, Star-Tek, Inc.
Keith McCloghrie, Hughes LAN Systems
Evan McGinnis, 3Com Corporation
Bill McKenzie, IBM Corporation
Donna McMaster, SynOptics Communications, Inc.
Case, McCloghrie, Rose & Waldbusser [Page 28]
RFC 1444 Conformance Statements for SNMPv2 April 1993
John Medicke, IBM Corporation
Doug Miller, Telebit
Dave Minnich, FiberCom
Mohammad Mirhakkak, MITRE
Rohit Mital, Protools
George Mouradian, AT&T Bell Labs
Patrick Mullaney, Cabletron Systems
Dan Myers, 3Com Corporation
Rina Nathaniel, Rad Network Devices Ltd.
Hien V. Nguyen, Sprint
Mo Nikain
Tom Nisbet
William B. Norton, MERIT
Steve Onishi, Wellfleet Communications, Inc.
David T. Perkins, SynOptics Communications, Inc.
Carl Powell, BBN
Ilan Raab, SynOptics Communications, Inc.
Richard Ramons, AT&T
Venkat D. Rangan, Metric Network Systems, Inc.
Louise Reingold, Sprint
Sam Roberts, Farallon Computing, Inc.
Kary Robertson, Concord Communications, Inc.
Dan Romascanu, Lannet Data Communications Ltd.
Marshall T. Rose, Dover Beach Consulting, Inc.
Shawn A. Routhier, Epilogue Technology Corporation
Chris Rozman
Asaf Rubissa, Fibronics
Jon Saperia, Digital Equipment Corporation
Michael Sapich
Mike Scanlon, Interlan
Sam Schaen, MITRE
John Seligson, Ultra Network Technologies
Paul A. Serice, Corporation for Open Systems
Chris Shaw, Banyan Systems
Timon Sloane
Robert Snyder, Cisco Systems
Joo Young Song
Roy Spitier, Sprint
Einar Stefferud, Network Management Associates
John Stephens, Cayman Systems, Inc.
Robert L. Stewart, Xyplex, Inc. (chair)
Kaj Tesink, Bellcore
Dean Throop, Data General
Ahmet Tuncay, France Telecom-CNET
Maurice Turcotte, Racal Datacom
Case, McCloghrie, Rose & Waldbusser [Page 29]
RFC 1444 Conformance Statements for SNMPv2 April 1993
Warren Vik, INTERACTIVE Systems Corporation
Yannis Viniotis
Steven L. Waldbusser, Carnegie Mellon Universitty
Timothy M. Walden, ACC
Alice Wang, Sun Microsystems
James Watt, Newbridge
Luanne Waul, Timeplex
Donald E. Westlake III, Digital Equipment Corporation
Gerry White
Bert Wijnen, IBM Corporation
Peter Wilson, 3Com Corporation
Steven Wong, Digital Equipment Corporation
Randy Worzella, IBM Corporation
Daniel Woycke, MITRE
Honda Wu
Jeff Yarnell, Protools
Chris Young, Cabletron
Kiho Yum, 3Com Corporation
Case, McCloghrie, Rose & Waldbusser [Page 30]
RFC 1444 Conformance Statements for SNMPv2 April 1993
8. 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)", RFC 1442,
SNMP Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[3] McCloghrie, K., and Rose, M., "Management Information
Base for Network Management of TCP/IP-based internets:
MIB-II", STD 17, RFC 1213, March 1991.
[4] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Management Information Base for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1450, SNMP
Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[5] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Protocol Operations for version 2 of the Simple Network
Management Protocol (SNMPv2)", RFC 1448, SNMP Research,
Inc., Hughes LAN Systems, Dover Beach Consulting, Inc.,
Carnegie Mellon University, April 1993.
[6] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Textual Conventions for version 2 of the the Simple
Network Management Protocol (SNMPv2)", RFC 1443, SNMP
Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[7] Rose, M., and McCloghrie, K., "Structure and
Identification of Management Information for TCP/IP-based
internets", STD 16, RFC 1155, May 1990.
[8] Rose, M., and McCloghrie, K., "Concise MIB Definitions",
STD 16, RFC 1212, March 1991.
Case, McCloghrie, Rose & Waldbusser [Page 31]
RFC 1444 Conformance Statements for SNMPv2 April 1993
9. Security Considerations
Security issues are not discussed in this memo.
10. Authors' Addresses
Jeffrey D. Case
SNMP Research, Inc.
3001 Kimberlin Heights Rd.
Knoxville, TN 37920-9716
US
Phone: +1 615 573 1434
Email:
[email protected]
Keith McCloghrie
Hughes LAN Systems
1225 Charleston Road
Mountain View, CA 94043
US
Phone: +1 415 966 7934
Email:
[email protected]
Marshall T. Rose
Dover Beach Consulting, Inc.
420 Whisman Court
Mountain View, CA 94043-2186
US
Phone: +1 415 968 1052
Email:
[email protected]
Steven Waldbusser
Carnegie Mellon University
4910 Forbes Ave
Pittsburgh, PA 15213
US
Phone: +1 412 268 6628
Email:
[email protected]
Case, McCloghrie, Rose & Waldbusser [Page 32]
