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RFC 3781 - Next Generation Structure of Management Information (


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Network Working Group                                         F. Strauss
Request for Comments: 3781                               TU Braunschweig
Category: Experimental                                  J. Schoenwaelder
                                         International University Bremen
                                                                May 2004

      Next Generation Structure of Management Information (SMIng)
       Mappings to the Simple Network Management Protocol (SNMP)

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   SMIng (Structure of Management Information, Next Generation)
   (RFC3780), is a protocol-independent data definition language for
   management information.  This memo defines an SMIng language
   extension that specifies the mapping of SMIng definitions of
   identities, classes, and their attributes and events to dedicated
   definitions of nodes, scalar objects, tables and columnar objects,
   and notifications, for application to the SNMP management framework.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  SNMP Based Internet Management . . . . . . . . . . . . . . . .  3
       2.1.   Kinds of Nodes. . . . . . . . . . . . . . . . . . . . .  4
       2.2.   Scalar and Columnar Object Instances. . . . . . . . . .  5
       2.3.   Object Identifier Hierarchy . . . . . . . . . . . . . .  7
   3.  SMIng Data Type Mappings . . . . . . . . . . . . . . . . . . .  8
       3.1.   ASN.1 Definitions . . . . . . . . . . . . . . . . . . .  9
   4.  The snmp Extension Statement . . . . . . . . . . . . . . . . . 10
       4.1.   The oid Statement . . . . . . . . . . . . . . . . . . . 10
       4.2.   The node Statement. . . . . . . . . . . . . . . . . . . 10
              4.2.1. The node's oid Statement . . . . . . . . . . . . 10
              4.2.2. The node's represents Statement. . . . . . . . . 10
              4.2.3. The node's status Statement. . . . . . . . . . . 11
              4.2.4. The node's description Statement . . . . . . . . 11
              4.2.5. The node's reference Statement . . . . . . . . . 11

              4.2.6. Usage Examples . . . . . . . . . . . . . . . . . 11
       4.3.   The scalars Statement . . . . . . . . . . . . . . . . . 11
              4.3.1. The scalars' oid Statement . . . . . . . . . . . 12
              4.3.2. The scalars' object Statement  . . . . . . . . . 12
              4.3.3. The scalars' status Statement  . . . . . . . . . 13
              4.3.4. The scalars' description Statement . . . . . . . 14
              4.3.5. The scalars' reference Statement . . . . . . . . 14
              4.3.6. Usage Example. . . . . . . . . . . . . . . . . . 14
       4.4.   The table Statement . . . . . . . . . . . . . . . . . . 14
              4.4.1. The table's oid Statement. . . . . . . . . . . . 15
              4.4.2. Table Indexing Statements. . . . . . . . . . . . 15
              4.4.3. The table's create Statement . . . . . . . . . . 17
              4.4.4. The table's object Statement . . . . . . . . . . 17
              4.4.5. The table's status Statement . . . . . . . . . . 19
              4.4.6. The table's description Statement  . . . . . . . 19
              4.4.7. The table's reference Statement  . . . . . . . . 19
              4.4.8. Usage Example  . . . . . . . . . . . . . . . . . 19
       4.5.   The notification Statement  . . . . . . . . . . . . . . 20
              4.5.1. The notification's oid Statement . . . . . . . . 20
              4.5.2. The notification's signals Statement . . . . . . 20
              4.5.3. The notification's status Statement  . . . . . . 20
              4.5.4. The notification's description Statement . . . . 21
              4.5.5. The notification's reference Statement . . . . . 21
              4.5.6. Usage Example. . . . . . . . . . . . . . . . . . 21
       4.6.   The group Statement . . . . . . . . . . . . . . . . . . 21
              4.6.1. The group's oid Statement  . . . . . . . . . . . 22
              4.6.2. The group's members Statement  . . . . . . . . . 22
              4.6.3. The group's status Statement . . . . . . . . . . 22
              4.6.4. The group's description Statement  . . . . . . . 22
              4.6.5. The group's reference Statement  . . . . . . . . 22
              4.6.6. Usage Example  . . . . . . . . . . . . . . . . . 22
       4.7.   The compliance Statement. . . . . . . . . . . . . . . . 23
              4.7.1. The compliance's oid Statement . . . . . . . . . 23
              4.7.2. The compliance's status Statement  . . . . . . . 23
              4.7.3. The compliance's description Statement . . . . . 23
              4.7.4. The compliance's reference Statement . . . . . . 23
              4.7.5. The compliance's mandatory Statement . . . . . . 24
              4.7.6. The compliance's optional Statement. . . . . . . 24
              4.7.7. The compliance's refine Statement  . . . . . . . 24
              4.7.8. Usage Example  . . . . . . . . . . . . . . . . . 26
   5.  NMRG-SMING-SNMP-EXT  . . . . . . . . . . . . . . . . . . . . . 26
   6.  NMRG-SMING-SNMP  . . . . . . . . . . . . . . . . . . . . . . . 33
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 46
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 46

   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 47
       9.1.   Normative References. . . . . . . . . . . . . . . . . . 47
       9.2.   Informative References. . . . . . . . . . . . . . . . . 47
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 48
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 49

1.  Introduction

   SMIng (Structure of Management Information, Next Generation)
   [RFC3780] is a protocol-independent data definition language for
   management information.  This memo defines an SMIng language
   extension that specifies the mapping of SMIng definitions of
   identities, classes, and their attributes and events to dedicated
   definitions of nodes, scalar objects, tables and columnar objects,
   and notifications for application in the SNMP management framework.
   Section 2 introduces basics of the SNMP management framework.
   Section 3 defines how SMIng data types are mapped to the data types
   supported by the SNMP protocol.  It introduces some new ASN.1 [ASN1]
   definitions which are used to represent new SMIng base types such as
   floats in the SNMP protocol.

   Section 4 describes the semantics of the SNMP mapping extensions for
   SMIng.  The formal SMIng specification of the extension is provided
   in Section 5.

   Section 6 contains an SMIng module which defines derived types (such
   as RowStatus) that are specific to the SNMP mapping.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  SNMP-Based Internet Management

   The SNMP network management framework [RFC3410] is based on the
   concept of "managed objects".  Managed objects represent real or
   synthesized variables of systems that are to be managed.  Note that
   in spite of these terms this model is not object-oriented.  For
   naming purposes, the managed objects are organized hierarchically in
   an "object identifier tree", where only leaf nodes may represent
   objects.

   Nodes in the object identifier tree may also identify conceptual
   tables, rows of conceptual tables, notifications, groups of objects
   and/or notifications, compliance statements, modules or other
   information.  Each node is identified by an unique "object
   identifier" value which is a sequence of non-negative numbers, named
   "sub-identifiers", where the left-most sub-identifier refers to the

   node next to the root of the tree and the right-most sub-identifier
   refers to the node that is identified by the complete object
   identifier value.  Each sub-identifier has a value between 0 and
   2^32-1 (4294967295).

   The SMIng extensions described in this document are used to map SMIng
   data definitions to SNMP compliant managed objects.  This mapping is
   designed to be readable to computer programs, named MIB compilers, as
   well as to human readers.

2.1.  Kinds of Nodes

   Each node in the object identifier tree is of a certain kind and may
   represent management information or not:

   o  Simple nodes, that do not represent management information, but
      may be used for grouping nodes in a subtree.  Those nodes are
      defined by the `node' statement.  This statement can also be used
      to map an SMIng `identity' to a node.

   o  Nodes representing the identity of a module to allow references to
      a module in other objects of type `ObjectIdentifier'.  Those nodes
      are defined by the `snmp' statement,

   o  Scalar objects, which have exactly one object instance and no
      child nodes.  See Section 2.2 for scalar objects' instances.  A
      set of scalar objects is mapped from one or more SMIng classes
      using the `scalars' statement.  The statement block of the
      `scalars' statement contains one `implements' statement for each
      class.  The associated statement blocks in turn contain `object'
      statements that specify the mapping of attributes to scalar
      objects.  Scalar objects MUST not have any child node.

   o  Tables, which represent the root node of a collection of
      information structured in table rows.  Table nodes are defined by
      the `table' statement.  A table object identifier SHOULD not have
      any other child node than the implicitly defined row node (see
      below).

   o  Rows, which belong to a table (that is, row's object identifier
      consists of the table's full object identifier plus a single `1'
      sub-identifier) and represent a sequence of one or more columnar
      objects.  A row node is implicitly defined for each table node.

   o  Columnar objects, which belong to a row (that is, the columnar
      objects' object identifier consists of the row's full object
      identifier plus a single column-identifying sub-identifier) and
      have zero or more object instances and no child nodes.  They are
      defined as follows: The classes that are implemented by a `table'
      statement are identified by `implements' statements.  The
      statement block of each `implements' statement contains `object'
      statements that specify the mapping of attributes to columnar
      objects of this table.  Columnar objects MUST not have any child
      node.

   o  Notifications, which represent information that is sent by agents
      within unsolicited transmissions.  The `notification' statement is
      used to map an SMIng event to a notification.  A notification's
      object identifier SHOULD not have any child node.

   o  Groups of objects and notifications, which may be used for
      compliance statements.  They are defined using the `group'
      statement.

   o  Compliance statements which define requirements for MIB module
      implementations.  They are defined using the `compliance'
      statement.

2.2.  Scalar and Columnar Object Instances

   Instances of managed objects are identified by appending an
   instance-identifier to the object's object identifier.  Scalar
   objects and columnar objects use different ways to construct the
   instance-identifier.

   Scalar objects have exactly one object instance.  It is identified by
   appending a single `0' sub-identifier to the object identifier of the
   scalar object.

   Within tables, different instances of the same columnar object are
   identified by appending a sequence of one or more sub-identifiers to
   the object identifier of the columnar object which consists of the
   values of object instances that unambiguously distinguish a table
   row.  These indexing objects can be columnar objects of the same
   and/or another table, but MUST NOT be scalar objects.  Multiple
   applications of the same object in a single table indexing
   specification are strongly discouraged.

   The base types of the indexing objects indicate how to form the
   instance-identifier:

   o  integer-valued or enumeration-valued: a single sub-identifier
      taking the integer value (this works only for non-negative
      integers and integers of a size of up to 32 bits),

   o  string-valued, fixed-length strings (or variable-length with
      compact encoding): `n' sub-identifiers, where `n' is the length of
      the string (each octet of the string is encoded in a separate
      sub-identifier),

   o  string-valued, variable-length strings or bits-valued: `n+1' sub-
      identifiers, where `n' is the length of the string or bits
      encoding (the first sub-identifier is `n' itself, following this,
      each octet of the string or bits is encoded in a separate sub-
      identifier),

   o  object identifier-valued (with compact encoding): `n' sub-
      identifiers, where `n' is the number of sub-identifiers in the
      value (each sub-identifier of the value is copied into a separate
      sub-identifier),

   o  object identifier-valued: `n+1' sub-identifiers, where `n' is the
      number of sub-identifiers in the value (the first sub-identifier
      is `n' itself, following this, each sub-identifier in the value is
      copied),

   Note that compact encoding can only be applied to an object having a
   variable-length syntax (e.g., variable-length strings, bits objects
   or object identifier-valued objects).  Further, compact encoding can
   only be associated with the last object in a list of indexing
   objects.  Finally, compact encoding MUST NOT be used on a variable-
   length string object if that string might have a value of zero-
   length.

   Instances identified by use of integer-valued or enumeration-valued
   objects are RECOMMENDED to be numbered starting from one (i.e., not
   from zero).  Integer objects that allow negative values, Unsigned64
   objects, Integer64 objects and floating point objects MUST NOT be
   used for table indexing.

   Objects which are both specified for indexing in a row and also
   columnar objects of the same row are termed auxiliary objects.
   Auxiliary objects SHOULD be non-accessible, except in the following
   circumstances:

   o  within a module originally written to conform to SMIv1, or

   o  a row must contain at least one columnar object which is not an
      auxiliary object.  In the event that all of a row's columnar
      objects are also specified to be indexing objects then one of them
      MUST be accessible.

2.3.  Object Identifier Hierarchy

   The layers of the object identifier tree near the root are well
   defined and organized by standardization bodies.  The first level
   next to the root has three nodes:

      0: ccitt

      1: iso

      2: joint-iso-ccitt

   Note that the renaming of the Commite Consultatif International de
   Telegraphique et Telephonique (CCITT) to International
   Telecommunications Union (ITU) had no consequence on the names used
   in the object identifier tree.

   The root of the subtree administered by the Internet Assigned Numbers
   Authority (IANA) for the Internet is `1.3.6.1' which is assigned with
   the identifier `internet'.  That is, the Internet subtree of object
   identifiers starts with the prefix `1.3.6.1.'.

   Several branches underneath this subtree are used for network
   management:

   The `mgmt' (internet.2) subtree is used to identify "standard"
   definitions.  An information module produced by an IETF working group
   becomes a "standard" information module when the document is first
   approved by the IESG and enters the Internet standards track.

   The `experimental' (internet.3) subtree is used to identify
   experimental definitions being designed by working groups of the IETF
   or IRTF.  If an information module produced by a working group
   becomes a "standard" module, then at the very beginning of its entry
   onto the Internet standards track, the definitions are moved under
   the mgmt subtree.

   The `private' (internet.4) subtree is used to identify definitions
   defined unilaterally.  The `enterprises' (private.1) subtree beneath
   private is used, among other things, to permit providers of
   networking subsystems to register information modules of their
   products.

   These and some other nodes are defined in the SMIng module NMRG-
   SMING-SNMP-EXT (Section 5).

3.  SMIng Data Type Mappings

   SMIng [RFC3780] supports the following set of base types:
   OctetString, Pointer, Integer32, Integer64, Unsigned32, Unsigned64,
   Float32, Float64, Float128, Enumeration, Bits, and ObjectIdentifier.

   The SMIng core module NMRG-SMING ([RFC3780], Appendix A) defines
   additional derived types, among them Counter32 (derived from
   Unsigned32), Counter64 (derived from Unsigned64), TimeTicks32 and
   TimeTicks64 (derived from Unsigned32 and Unsigned64), IpAddress
   (derived from OctetString), and Opaque (derived from OctetString).

   The version 2 of the protocol operations for SNMP document [RFC3416]
   defines the following 9 data types which are distinguished by the
   protocol: INTEGER, OCTET STRING, OBJECT IDENTIFIER, IpAddress,
   Counter32, TimeTicks, Opaque, Counter64, and Unsigned32.

   The SMIng base types and their derived types are mapped to SNMP data
   types according to the following table:

         SMIng Data Type    SNMP Data Type         Comment
         ---------------    -------------------    -------
         OctetString        OCTET STRING           (1)
         Pointer            OBJECT IDENTIFIER
         Integer32          INTEGER
         Integer64          Opaque (Integer64)     (2)
         Unsigned32         Unsigned32             (3)
         Unsigned64         Opaque (Unsigned64)    (2) (4)
         Float32            Opaque (Float32)       (2)
         Float64            Opaque (Float64)       (2)
         Float128           Opaque (Float128)      (2)
         Enumeration        INTEGER
         Bits               OCTET STRING
         ObjectIdentifier   OBJECT IDENTIFIER

         Counter32          Counter32
         Counter64          Counter64
         TimeTicks32        TimeTicks
         TimeTicks64        Opaque (Unsigned64)    (2)
         IpAddress          IpAddress
         Opaque             Opaque

      (1) This mapping includes all types derived from the OctetString
          type except those types derived from the IpAddress and Opaque
          SMIng types defined in the module NMRG-SMING.

      (2) This type is encoded according to the ASN.1 type with the same
          name defined in Section 3.1.  The resulting BER encoded value
          is then wrapped in an Opaque value.

      (3) This mapping includes all types derived from the Unsigned32
          type except those types derived from the Counter32 and
          TimeTicks32 SMIng types defined in the module NMRG-SMING.

      (4) This mapping includes all types derived from the Unsigned64
          type except those types derived from the Counter64 SMIng type
          defined in the module NMRG-SMING.

3.1.  ASN.1 Definitions

   The ASN.1 [ASN1] type definitions below introduce data types which
   are used to map the new SMIng base types into the set of ASN.1 types
   supported by the second version of SNMP protocol operations
   [RFC3416].

   NMRG-SMING-SNMP-MAPPING DEFINITIONS ::= BEGIN

   Integer64 ::=
       [APPLICATION 10]
           IMPLICIT INTEGER (-9223372036854775808..9223372036854775807)

   Unsigned64
       [APPLICATION 11]
           IMPLICIT INTEGER (0..18446744073709551615)

   Float32
       [APPLICATION 12]
           IMPLICIT OCTET STRING (SIZE (4))

   Float64
       [APPLICATION 13]
           IMPLICIT OCTET STRING (SIZE (8))

   Float128
       [APPLICATION 14]
           IMPLICIT OCTET STRING (SIZE (16))

   END

   The definitions of Integer64 and Unsigned64 are consistent with the
   same definitions in the SPPI [RFC3159].  The floating point types
   Float32, Float64 and Float128 support single, double and quadruple

   IEEE floating point values.  The encoding of the values follows the
   "IEEE Standard for Binary Floating-Point Arithmetic" as defined in
   ANSI/IEEE Standard 754-1985 [IEEE754].

4.  The snmp Extension Statement

   The `snmp' statement is the main statement of the SNMP mapping
   specification.  It gets one or two arguments: an optional lower-case
   identifier that specifies a node that represents the module's
   identity, and a mandatory statement block that contains all details
   of the SNMP mapping.  All information of an SNMP mapping are mapped
   to an SNMP conformant module of the same name as the containing SMIng
   module.  A single SMIng module must not contain more than one `snmp'
   statement.

4.1.  The oid Statement

   The snmp's `oid' statement, which must be present, if the snmp
   statement contains a module identifier and must be absent otherwise,
   gets one argument which specifies the object identifier value that is
   assigned to this module's identity node.

4.2.  The node Statement

   The `node' statement is used to name and describe a node in the
   object identifier tree, without associating any class or attribute
   information with this node.  This may be useful to group definitions
   in a subtree of related management information, or to uniquely define
   an SMIng `identity' to be referenced in attributes of type Pointer.
   The `node' statement gets two arguments: a lower-case node identifier
   and a statement block that holds detailed node information in an
   obligatory order.

   See the `nodeStatement' rule of the grammar (Section 5) for the
   formal syntax of the `node' statement.

4.2.1.  The node's oid Statement

   The node's `oid' statement, which must be present, gets one argument
   which specifies the object identifier value that is assigned to this
   node.

4.2.2.  The node's represents Statement

   The node's `represents' statement, which need not be present, makes
   this node represent an SMIng identity, so that objects of type
   Pointer can reference that identity.  The statement gets one argument
   which specifies the identity name.

4.2.3 The node's status Statement

   The node's `status' statement, which must be present, gets one
   argument which is used to specify whether this node definition is
   current or historic.  The value `current' means that the definition
   is current and valid.  The value `obsolete' means the definition is
   obsolete and should not be implemented and/or can be removed if
   previously implemented.  While the value `deprecated' also indicates
   an obsolete definition, it permits new/continued implementation in
   order to foster interoperability with older/existing implementations.

4.2.4.  The node's description Statement

   The node's `description' statement, which need not be present, gets
   one argument which is used to specify a high-level textual
   description of this node.

   It is RECOMMENDED to include all semantics and purposes of this node.

4.2.5.  The node's reference Statement

   The node's `reference' statement, which need not be present, gets one
   argument which is used to specify a textual cross-reference to some
   other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this node.

4.2.6.  Usage Examples

   node iso                            { oid 1;     status current; };
   node   org                          { oid iso.3; status current; };
   node     dod                        { oid org.6; status current; };
   node       internet                 { oid dod.1; status current; };

   node   zeroDotZero {
       oid         0.0;
       represents  NMRG-SMING::null;
       status      current;
       description "A null value used for pointers.";
   };

4.3.  The scalars Statement

   The `scalars' statement is used to define the mapping of one or more
   classes to a group of SNMP scalar managed objects organized under a
   common parent node.  The `scalars' statement gets two arguments: a

   lower-case scalar group identifier and a statement block that holds
   detailed mapping information of this scalar group in an obligatory
   order.

   See the `scalarsStatement' rule of the grammar (Section 5) for the
   formal syntax of the `scalars' statement.

4.3.1.  The scalars' oid Statement

   The scalars' `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is assigned
   to the common parent node of this scalar group.

4.3.2.  The scalars' object Statement

   The scalars' `object' statement, which must be present at least once,
   makes this scalar group contain a given scalar object.  It gets two
   arguments: the name of the scalar object to be defined and a
   statement block that holds additional detailed information in an
   obligatory order.

4.3.2.1.  The object's implements Statement

   The `implements' statement, which must be present, is used to specify
   a single leaf attribute of a class that is implemented by this scalar
   object.  The type of this attribute must be a simple type, i.e., not
   a class.

4.3.2.2.  The object's subid Statement

   The `subid' statement, which need not be present, is used to specify
   the sub-identifier that identifies the scalar object within this
   scalar group, i.e., the object identifier of the scalar object is the
   concatenation of the values of this scalar group's oid statement and
   of this subid statement.

   If this statement is omitted, the sub-identifier is the one of the
   previous object statement within this scalar group plus 1.  If the
   containing object statement is the first one within the containing
   scalar group and the subid statement is omitted, the sub-identifier
   is 1.

4.3.2.3.  The object's status Statement

   The object's `status' statement, which need not be present, gets one
   argument which is used to specify whether this scalar object
   definition is current or historic.  The value `current' means that

   the definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated' also
   indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations.

   Scalar objects SHOULD NOT be defined as `current' if the implemented
   attribute definition is `deprecated' or `obsolete'.  Similarly, they
   SHOULD NOT be defined as `deprecated' if the implemented attribute is
   `obsolete'.  Nevertheless, subsequent revisions of used class
   definitions cannot be avoided, but SHOULD be taken into account in
   subsequent revisions of the local module.

   Note that it is RECOMMENDED to omit the status statement which means
   that the status is inherited from the containing scalars statement.
   However, if the status of a scalar object varies from the containing
   scalar group, it has to be expressed explicitly, e.g., if the
   implemented attribute has been deprecated or obsoleted.

4.3.2.4.  The object's description Statement

   The object's `description' statement, which need not be present, gets
   one argument which is used to specify a high-level textual
   description of this scalar object.

   Note that in contrast to other definitions this description statement
   is not mandatory and it is RECOMMENDED to omit it, if the object is
   fully described by the description of the implemented attribute.

4.3.2.5.  The object's reference Statement

   The object's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this scalar object.

   It is RECOMMENDED to omit this statement, if the object's references
   are fully described by the implemented attribute.

4.3.3.  The scalars' status Statement

   The scalars' `status' statement, which must be present, gets one
   argument which is used to specify whether this scalar group
   definition is current or historic.  The value `current' means that
   the definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be

   removed if previously implemented.  While the value `deprecated' also
   indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations.

4.3.4.  The scalars' description Statement

   The scalars' `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description of
   this scalar group.

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this scalar group.

4.3.5.  The scalars' reference Statement

   The scalars' `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this scalars statement.

4.3.6.  Usage Example

   scalars ip {
     oid             mib-2.4;
     object ipForwarding { implements Ip.forwarding; };
     object ipDefaultTTL { implements Ip.defaultTTL; };
     // ...
     status          current;
     description
             "This scalar group implements the Ip class.";
   };

4.4.  The table Statement

   The `table' statement is used to define the mapping of one or more
   classes to a single SNMP table of columnar managed objects.  The
   `table' statement gets two arguments: a lower-case table identifier
   and a statement block that holds detailed mapping information of this
   table in an obligatory order.

   See the `tableStatement' rule of the grammar (Section 5) for the
   formal syntax of the `table' statement.

4.4.1.  The table's oid Statement

   The table's `oid' statement, which must be present, gets one argument
   which specifies the object identifier value that is assigned to this
   table's node.

4.4.2.  Table Indexing Statements

   SNMP table mappings offers five methods to supply table indexing
   information: ordinary tables, table augmentations, sparse table
   augmentations, table expansions, and reordered tables use different
   statements to denote their indexing information.  Each table
   definition must contain exactly one of the following indexing
   statements.

4.4.2.1.  The table's index Statement for Table Indexing

   The table's `index' statement, which is used to supply table indexing
   information of base tables, gets one argument that specifies a
   comma-separated list of objects, that are used for table indexing,
   enclosed in parenthesis.

   The elements of the `unique' statement of the implemented class(es)
   and their order should be regarded as a hint for the index elements
   of the table.

   In case of modules that should be compatible on the SNMP protocol
   level to SMIv2 versions of the module, an optional `implied' keyword
   may be added in front of the list to indicate a compact encoding of
   the last object in the list.  See Section 2.2 for details.

4.4.2.2.  The table's augments Statement for Table Indexing

   The table's `augments' statement, which is used to supply table
   indexing information of tables that augment a base table, gets one
   argument that specifies the identifier of the table to be augmented.
   Note that a table augmentation cannot itself be augmented.  Anyhow, a
   base table may be augmented by multiple table augmentations.

   A table augmentation makes instances of subordinate columnar objects
   identified according to the index specification of the base table
   corresponding to the table named in the `augments' statement.
   Further, instances of subordinate columnar objects of a table
   augmentation exist according to the same semantics as instances of
   subordinate columnar objects of the base table being augmented.  As
   such, note that creation of a base table row implies the

   correspondent creation of any table row augmentations.  Table
   augmentations MUST NOT be used in table row creation and deletion
   operations.

4.4.2.3.  The table's extends Statement for Table Indexing

   The table's `extends' statement, which is used to supply table
   indexing information of tables that sparsely augment a base table,
   gets one argument that specifies the identifier of the table to be
   sparsely augmented.  Note that a sparse table augmentation cannot
   itself be augmented.  Anyhow, a base table may be augmented by
   multiple table augmentations, sparsely or not.

   A sparse table augmentation makes instances of subordinate columnar
   objects identified, if present, according to the index specification
   of the base table corresponding to the table named in the `extends'
   statement.  Further, instances of subordinate columnar objects of a
   sparse table augmentation exist according to the semantics as
   instances of subordinate columnar objects of the base table and the
   (non-formal) rules that confine the sparse relationship.  As such,
   note that creation of a sparse table row augmentation may be implied
   by the creation of a base table row as well as done by an explicit
   creation.  However, if a base table row gets deleted, any dependent
   sparse table row augmentations get also deleted implicitly.

4.4.2.4.  The table's reorders Statement for Table Indexing

   The table's `reorders' statement is used to supply table indexing
   information of tables, that contain exactly the same index objects of
   a base table but in a different order.  It gets at least two
   arguments.  The first one specifies the identifier of the base table.
   The second one specifies a comma-separated list of exactly those
   object identifiers of the base table's `index' statement, but in the
   order to be used in this table.  Note that a reordered table cannot
   itself be reordered.  Anyhow, a base table may be used for multiple
   reordered tables.

   Under some circumstances, an optional `implied' keyword may be added
   in front of the list to indicate a compact encoding of the last
   object in the list.  See Section 2.2 for details.

   Instances of subordinate columnar objects of a reordered table exist
   according to the same semantics as instances of subordinate columnar
   objects of the base table.  As such, note that creation of a base
   table row implies the correspondent creation of any related reordered
   table row.  Reordered tables MUST NOT be used in table row creation
   and deletion operations.

4.4.2.5.  The table's expands Statement for Table Indexing

   The table's `expands' statement is used to supply table indexing
   information of table expansions.  Table expansions use exactly the
   same index objects of another table together with additional indexing
   objects.  Thus, the `expands' statement gets at least two arguments.
   The first one specifies the identifier of the base table.  The second
   one specifies a comma-separated list of the additional object
   identifiers used for indexing.  Note that an expanded table may
   itself be expanded, and base tables may be used for multiple table
   expansions.

   Under some circumstances, an optional `implied' keyword may be added
   in front of the list to indicate a compact encoding of the last
   object in the list.  See Section 2.2 for details.

4.4.3.  The table's create Statement

   The table's `create' statement, which need not be present, gets no
   argument.  If the `create' statement is present, table row creation
   (and deletion) is possible.

4.4.4.  The table's object Statement

   The table's `object' statement, which must be present at least once,
   makes this table contain a given columnar object.  It gets two
   arguments: the name of the columnar object to be defined and a
   statement block that holds additional detailed information in an
   obligatory order.

4.4.4.1.  The object's implements Statement

   The `implements' statement, which must be present, is used to specify
   a single leaf attribute of a class that is implemented by this
   columnar object.  The type of this attribute must be a simple type,
   i.e., not a class.

4.4.4.2.  The object's subid Statement

   The `subid' statement, which need not be present, is used to specify
   the sub-identifier that identifies the columnar object within this
   table, i.e., the object identifier of the columnar object is the
   concatenation of the values of this table's oid statement and of this
   subid statement.

   If this statement is omitted, the sub-identifier is the one of the
   previous object statement within this table plus 1.  If the
   containing object statement is the first one within the containing
   table and the subid statement is omitted, the sub-identifier is 1.

4.4.4.3.  The object's status Statement

   The object's `status' statement, which need not be present, gets one
   argument which is used to specify whether this columnar object
   definition is current or historic.  The value `current' means that
   the definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated' also
   indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations.

   Columnar objects SHOULD NOT be defined as `current' if the
   implemented attribute definition is `deprecated' or `obsolete'.
   Similarly, they SHOULD NOT be defined as `deprecated' if the
   implemented attribute is `obsolete'.  Nevertheless, subsequent
   revisions of used class definitions cannot be avoided, but SHOULD be
   taken into account in subsequent revisions of the local module.

   Note that it is RECOMMENDED to omit the status statement which means
   that the status is inherited from the containing table statement.
   However, if the status of a columnar object varies from the
   containing table, it has to be expressed explicitly, e.g., if the
   implemented attribute has been deprecated or obsoleted.

4.4.4.4.  The object's description Statement

   The object's `description' statement, which need not be present, gets
   one argument which is used to specify a high-level textual
   description of this columnar object.

   Note that in contrast to other definitions this description statement
   is not mandatory and it is RECOMMENDED to omit it, if the object is
   fully described by the description of the implemented attribute.

4.4.4.5.  The object's reference Statement

   The object's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this columnar object.

   It is RECOMMENDED to omit this statement, if the object's references
   are fully described by the implemented attribute.

4.4.5.  The table's status Statement

   The table's `status' statement, which must be present, gets one
   argument which is used to specify whether this table definition is
   current or historic.  The value `current' means that the definition
   is current and valid.  The value `obsolete' means the definition is
   obsolete and should not be implemented and/or can be removed if
   previously implemented.  While the value `deprecated' also indicates
   an obsolete definition, it permits new/continued implementation in
   order to foster interoperability with older/existing implementations.

4.4.6.  The table's description Statement

   The table's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description of
   this table.

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this table.

4.4.7.  The table's reference Statement

   The table's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this table statement.

4.4.8.  Usage Example

   table ifTable {
     oid             interfaces.2;
     index           (ifIndex);
     object ifIndex { implements Interface.index;       };
     object ifDescr { implements Interface.description; };
     // ...
     status          current;
     description
             "This table implements the Interface class.";
   };

4.5.  The notification Statement

   The `notification' statement is used to map events defined within
   classes to SNMP notifications.  The `notification' statement gets two
   arguments: a lower-case notification identifier and a statement block
   that holds detailed notification information in an obligatory order.

   See the `notificationStatement' rule of the grammar (Section 5) for
   the formal syntax of the `notification' statement.

4.5.1.  The notification's oid Statement

   The notification's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is assigned
   to this notification.

4.5.2.  The notification's signals Statement

   The notification's `signals' statement, which must be present,
   denotes the event that is signaled by this notification.  The
   statement gets two arguments: the event to be signaled (in the
   qualified form `Class.event') and a statement block that holds
   detailed information on the objects transmitted with this
   notification in an obligatory order.

4.5.2.1.  The signals' object Statement

   The signals' `object' statement, which can be present zero, one or
   multiple times, makes a single instance of a class attribute be
   contained in this notification.  It gets one argument: the specific
   class attribute.  The namespace of attributes not specified by
   qualified names is the namespace of the event's class specified in
   the `signals' statement.

4.5.3.  The notification's status Statement

   The notification's `status' statement, which must be present, gets
   one argument which is used to specify whether this notification
   definition is current or historic.  The value `current' means that
   the definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated' also
   indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations.

4.5.4.  The notification's description Statement

   The notification's `description' statement, which need not be
   present, gets one argument which is used to specify a high-level
   textual description of this notification.

   It is RECOMMENDED to include all semantics and purposes of this
   notification.

4.5.5.  The notification's reference Statement

   The notification's `reference' statement, which need not be present,
   gets one argument which is used to specify a textual cross-reference
   to some other document, either another module which defines related
   definitions, or some other document which provides additional
   information relevant to this notification statement.

4.5.6.  Usage Example

   notification linkDown {
       oid         snmpTraps.3;
       signals     Interface.linkDown {
           object      ifIndex;
           object      ifAdminStatus;
           object      ifOperStatus;
       };
       status      current;
       description
             "This notification signals the linkDown event
              of the Interface class.";
   };

4.6.  The group Statement

   The `group' statement is used to define a group of arbitrary nodes in
   the object identifier tree.  It gets two arguments: a lower-case
   group identifier and a statement block that holds detailed group
   information in an obligatory order.

   Note that the primary application of groups are compliance
   statements, although they might be referred in other formal or
   informal documents.

   See the `groupStatement' rule of the grammar (Section 5) for the
   formal syntax of the `group' statement.

4.6.1.  The group's oid Statement

   The group's `oid' statement, which must be present, gets one argument
   which specifies the object identifier value that is assigned to this
   group.

4.6.2.  The group's members Statement

   The group's `members' statement, which must be present, gets one
   argument which specifies the list of nodes by their identifiers to be
   contained in this group.  The list of nodes has to be comma-separated
   and enclosed in parenthesis.

4.6.3.  The group's status Statement

   The group's `status' statement, which must be present, gets one
   argument which is used to specify whether this group definition is
   current or historic.  The value `current' means that the definition
   is current and valid.  The value `obsolete' means the definition is
   obsolete and the group should no longer be used.  While the value
   `deprecated' also indicates an obsolete definition, it permits
   new/continued use of this group.

4.6.4.  The group's description Statement

   The group's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description of
   this group.  It is RECOMMENDED to include any relation to other
   groups.

4.6.5.  The group's reference Statement

   The group's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   groups, or some other document which provides additional information
   relevant to this group.

4.6.6.  Usage Example

   The snmpGroup, originally defined in [RFC3418], may be described as
   follows:

   group snmpGroup {
     oid             snmpMIBGroups.8;
     objects         (snmpInPkts, snmpInBadVersions,
                      snmpInASNParseErrs,
                      snmpSilentDrops, snmpProxyDrops,

                      snmpEnableAuthenTraps);
     status          current;
     description
             "A collection of objects providing basic
              instrumentation and control of an agent.";
   };

4.7.  The compliance Statement

   The `compliance' statement is used to define a set of conformance
   requirements, named a `compliance statement'.  It gets two arguments:
   a lower-case compliance identifier and a statement block that holds
   detailed compliance information in an obligatory order.

   See the `complianceStatement' rule of the grammar (Section 5) for the
   formal syntax of the `compliance' statement.

4.7.1.  The compliance's oid Statement

   The compliance's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is assigned
   to this compliance statement.

4.7.2.  The compliance's status Statement

   The compliance's `status' statement, which must be present, gets one
   argument which is used to specify whether this compliance statement
   is current or historic.  The value `current' means that the
   definition is current and valid.  The value `obsolete' means the
   definition is obsolete and no longer specifies a valid definition of
   conformance.  While the value `deprecated' also indicates an obsolete
   definition, it permits new/continued use of the compliance
   specification.

4.7.3.  The compliance's description Statement

   The compliance's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of this compliance statement.

4.7.4.  The compliance's reference Statement

   The compliance's `reference' statement, which need not be present,
   gets one argument which is used to specify a textual cross-reference
   to some other document, either another module which defines related
   compliance statements, or some other document which provides
   additional information relevant to this compliance statement.

4.7.5.  The compliance's mandatory Statement

   The compliance's `mandatory' statement, which need not be present,
   gets one argument which is used to specify a comma-separated list of
   one or more groups (Section 4.6) of objects and/or notifications
   enclosed in parenthesis.  These groups are unconditionally mandatory
   for implementation.

   If an agent claims compliance to a MIB module then it must implement
   each and every object and notification within each group listed in
   the `mandatory' statement(s) of the compliance statement(s) of that
   module.

4.7.6.  The compliance's optional Statement

   The compliance's `optional' statement, which need not be present, is
   repeatedly used to name each group which is conditionally mandatory
   for compliance to the compliance statement.  It can also be used to
   name unconditionally optional groups.  A group named in an `optional'
   statement MUST be absent from the correspondent `mandatory'
   statement.  The `optional' statement gets two arguments: a lower-case
   group identifier and a statement block that holds detailed compliance
   information on that group.

   Conditionally mandatory groups include those groups which are
   mandatory only if a particular protocol is implemented, or only if
   another group is implemented.  The `description' statement specifies
   the conditions under which the group is conditionally mandatory.

   A group which is named in neither a `mandatory' statement nor an
   `optional' statement, is unconditionally optional for compliance to
   the module.

   See the `optionalStatement' rule of the grammar (Section 5) for the
   formal syntax of the `optional' statement.

4.7.6.1.  The optional's description Statement

   The optional's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the conditions under which this group is conditionally
   mandatory or unconditionally optional.

4.7.7.  The compliance's refine Statement

   The compliance's `refine' statement, which need not be present, is
   repeatedly used to specify each object for which compliance has a
   refined requirement with respect to the module definition.  The

   object must be present in one of the conformance groups named in the
   correspondent `mandatory' or `optional' statements.  The `refine'
   statement gets two arguments: a lower-case identifier of a scalar or
   columnar object and a statement block that holds detailed refinement
   information on that object.

   See the `refineStatement' rule of the grammar (Section 5) for the
   formal syntax of the `refine' statement.

4.7.7.1. The refine's type Statement

   The refine's `type' statement, which need not be present, gets one
   argument that is used to provide a refined type for the correspondent
   object.  Type restrictions may be applied by appending subtyping
   information according to the rules of the base type.  See [RFC3780]
   for SMIng base types and their type restrictions.  In case of
   enumeration or bitset types the order of named numbers is not
   significant.

   Note that if a `type' and a `writetype' statement are both present
   then this type only applies when instances of the correspondent
   object are read.

4.7.7.2.  The refine's writetype Statement

   The refine's `writetype' statement, which need not be present, gets
   one argument that is used to provide a refined type for the
   correspondent object, only when instances of that object are written.
   Type restrictions may be applied by appending subtyping information
   according to the rules of the base type.  See [RFC3780] for SMIng
   base types and their type restrictions.  In case of enumeration or
   bitset types the order of named numbers is not significant.

4.7.7.3.  The refine's access Statement

   The refine's `access' statement, which need not be present, gets one
   argument that is used to specify the minimal level of access that the
   correspondent object must implement in the sense of its original
   `access' statement.  Hence, the refine's `access' statement MUST NOT
   specify a greater level of access than is specified in the
   correspondent object definition.

   An implementation is compliant if the level of access it provides is
   greater or equal to the minimal level in the refine's `access'
   statement and less or equal to the maximal level in the object's
   `access' statement.

4.7.7.4.  The refine's description Statement

   The refine's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description of
   the refined compliance requirement.

4.7.8.  Usage Example

   The compliance statement contained in the SNMPv2-MIB [RFC3418],
   converted to SMIng:

      compliance snmpBasicComplianceRev2 {
        oid             snmpMIBCompliances.3;
        status          current;
        description
                "The compliance statement for SNMP entities which
                 implement this MIB module.";

        mandatory       (snmpGroup, snmpSetGroup, systemGroup,
                         snmpBasicNotificationsGroup);

        optional snmpCommunityGroup {
          description
                "This group is mandatory for SNMP entities which
                 support community-based authentication.";
        };
        optional snmpWarmStartNotificationGroup {
          description
                "This group is mandatory for an SNMP entity which
                 supports command responder applications, and is
                 able to reinitialize itself such that its
                 configuration is unaltered.";
        };
      };

5. NMRG-SMING-SNMP-EXT

   The grammar of the snmp statement (including all its contained
   statements) conforms to the Augmented Backus-Naur Form (ABNF)
   [RFC2234].  It is included in the abnf statement of the snmp SMIng
   extension definition in the NMRG-SMING-SNMP-EXT module below.

   module NMRG-SMING-SNMP-EXT {

      organization    "IRTF Network Management Research Group (NMRG)";

      contact         "IRTF Network Management Research Group (NMRG)
                       http://www.ibr.cs.tu-bs.de/projects/nmrg/

                       Frank Strauss
                       TU Braunschweig
                       Muehlenpfordtstrasse 23
                       38106 Braunschweig
                       Germany
                       Phone: +49 531 391 3266
                       EMail: strauss@ibr.cs.tu-bs.de

                       Juergen Schoenwaelder
                       International University Bremen
                       P.O. Box 750 561
                       28725 Bremen
                       Germany
                       Phone: +49 421 200 3587
                       EMail: j.schoenwaelder@iu-bremen.de";

      description     "This module defines a SMIng extension to define
                       the mapping of SMIng definitions of class and
                       their attributes and events to SNMP compatible
                       definitions of modules, node, scalars, tables,
                       and notifications, and additional information on
                       module compliances.

                       Copyright (C) The Internet Society (2004).
                       All Rights Reserved.
                       This version of this module is part of
                       RFC 3781, see the RFC itself for full
                       legal notices.";

      revision {
          date        "2003-12-16";
          description "Initial revision, published as RFC 3781.";
      };

      //
      //
      //

      extension snmp {

          status          current;
          description
             "The snmp statement maps SMIng definitions to SNMP
              conformant definitions.";
          abnf "
 ;;
 ;; sming-snmp.abnf -- Grammar of SNMP mappings in ABNF
 ;;                    notation (RFC 2234).

 ;;
 ;; @(#) $Id: sming-snmp.abnf,v 1.14 2003/10/23 19:31:55 strauss Exp $
 ;;
 ;; Copyright (C) The Internet Society (2004). All Rights Reserved.
 ;;

 ;;
 ;; Statement rules.
 ;;

 snmpStatement           = snmpKeyword *1(sep lcIdentifier) optsep
                               \"{\" stmtsep
                               *1(oidStatement stmtsep)
                               *(nodeStatement stmtsep)
                               *(scalarsStatement stmtsep)
                               *(tableStatement stmtsep)
                               *(notificationStatement stmtsep)
                               *(groupStatement stmtsep)
                               *(complianceStatement stmtsep)
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 nodeStatement           = nodeKeyword sep lcIdentifier optsep
                               \"{\" stmtsep
                               oidStatement stmtsep
                               *1(representsStatement stmtsep)
                               statusStatement stmtsep
                               *1(descriptionStatement stmtsep)
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 representsStatement     = representsKeyword sep
                               qucIdentifier optsep \";\"

 scalarsStatement        = scalarsKeyword sep lcIdentifier optsep
                               \"{\" stmtsep
                               oidStatement stmtsep
                               1*(objectStatement stmtsep)
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 tableStatement          = tableKeyword sep lcIdentifier optsep
                               \"{\" stmtsep
                               oidStatement stmtsep

                               anyIndexStatement stmtsep
                               *1(createStatement stmtsep)
                               1*(objectStatement stmtsep)
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 objectStatement         = objectKeyword sep lcIdentifier optsep
                               \"{\" stmtsep
                               implementsStatement stmtsep
                               *1(subidStatement stmtsep)
                               *1(statusStatement stmtsep)
                               *1(descriptionStatement stmtsep)
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 implementsStatement     = implementsKeyword sep qcattrIdentifier
                               optsep \";\"

 notificationStatement   = notificationKeyword sep lcIdentifier
                               optsep \"{\" stmtsep
                               oidStatement stmtsep
                               signalsStatement stmtsep
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 signalsStatement        = signalsKeyword sep qattrIdentifier
                               optsep \"{\" stmtsep
                               *(signalsObjectStatement)
                           \"}\" optsep \";\"

 signalsObjectStatement  = objectKeyword sep
                               qattrIdentifier optsep \";\"

 groupStatement          = groupKeyword sep lcIdentifier optsep
                               \"{\" stmtsep
                               oidStatement stmtsep
                               membersStatement stmtsep
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                           \"}\" optsep \";\"

 complianceStatement     = complianceKeyword sep lcIdentifier optsep
                               \"{\" stmtsep

                               oidStatement stmtsep
                               statusStatement stmtsep
                               descriptionStatement stmtsep
                               *1(referenceStatement stmtsep)
                               *1(mandatoryStatement stmtsep)
                               *(optionalStatement stmtsep)
                               *(refineStatement stmtsep)
                           \"}\" optsep \";\"

 anyIndexStatement       = indexStatement /
                           augmentsStatement /
                           reordersStatement /
                           extendsStatement /
                           expandsStatement

 indexStatement          = indexKeyword *1(sep impliedKeyword) optsep
                               \"(\" optsep qlcIdentifierList
                               optsep \")\" optsep \";\"

 augmentsStatement       = augmentsKeyword sep qlcIdentifier
                               optsep \";\"

 reordersStatement       = reordersKeyword sep qlcIdentifier
                               *1(sep impliedKeyword)
                               optsep \"(\" optsep
                               qlcIdentifierList optsep \")\"
                               optsep \";\"

 extendsStatement        = extendsKeyword sep qlcIdentifier optsep \";\"

 expandsStatement        = expandsKeyword sep qlcIdentifier
                               *1(sep impliedKeyword)
                               optsep \"(\" optsep
                               qlcIdentifierList optsep \")\"
                               optsep \";\"

 createStatement         = createKeyword optsep \";\"

 membersStatement        = membersKeyword optsep \"(\" optsep
                               qlcIdentifierList optsep
                               \")\" optsep \";\"

 mandatoryStatement      = mandatoryKeyword optsep \"(\" optsep
                               qlcIdentifierList optsep
                               \")\" optsep \";\"

 optionalStatement       = optionalKeyword sep qlcIdentifier optsep
                               \"{\" descriptionStatement stmtsep

                           \"}\" optsep \";\"

 refineStatement         = refineKeyword sep qlcIdentifier optsep \"{\"
                               *1(typeStatement stmtsep)
                               *1(writetypeStatement stmtsep)
                               *1(accessStatement stmtsep)
                               descriptionStatement stmtsep
                           \"}\" optsep \";\"

 typeStatement           = typeKeyword sep
                               (refinedBaseType / refinedType)
                               optsep \";\"

 writetypeStatement      = writetypeKeyword sep
                               (refinedBaseType / refinedType)
                               optsep \";\"

 oidStatement            = oidKeyword sep objectIdentifier optsep \";\"

 subidStatement          = subidKeyword sep subid optsep \";\"

 ;;
 ;; Statement keywords.
 ;;

 snmpKeyword         =  %x73 %x6E %x6D %x70
 nodeKeyword         =  %x6E %x6F %x64 %x65
 representsKeyword   =  %x72 %x65 %x70 %x72 %x65 %x73 %x65 %x6E %x74
                        %x73
 scalarsKeyword      =  %x73 %x63 %x61 %x6C %x61 %x72 %x73
 tableKeyword        =  %x74 %x61 %x62 %x6C %x65
 implementsKeyword   =  %x69 %x6D %x70 %x6C %x65 %x6D %x65 %x6E %x74
                        %x73
 subidKeyword        =  %x73 %x75 %x62 %x69 %x64
 objectKeyword       =  %x6F %x62 %x6A %x65 %x63 %x74
 notificationKeyword =  %x6E %x6F %x74 %x69 %x66 %x69 %x63 %x61 %x74
                        %x69 %x6F %x6E
 signalsKeyword      =  %x73 %x69 %x67 %x6E %x61 %x6C %x73
 oidKeyword          =  %x6F %x69 %x64
 groupKeyword        =  %x67 %x72 %x6F %x75 %x70
 complianceKeyword   =  %x63 %x6F %x6D %x70 %x6C %x69 %x61 %x6E %x63
                        %x65
 impliedKeyword      =  %x69 %x6D %x70 %x6C %x69 %x65 %x64
 indexKeyword        =  %x69 %x6E %x64 %x65 %x78
 augmentsKeyword     =  %x61 %x75 %x67 %x6D %x65 %x6E %x74 %x73
 reordersKeyword     =  %x72 %x65 %x6F %x72 %x64 %x65 %x72 %x73
 extendsKeyword      =  %x65 %x78 %x74 %x65 %x6E %x64 %x73
 expandsKeyword      =  %x65 %x78 %x70 %x61 %x6E %x64 %x73

 createKeyword       =  %x63 %x72 %x65 %x61 %x74 %x65
 membersKeyword      =  %x6D %x65 %x6D %x62 %x65 %x72 %x73
 mandatoryKeyword    =  %x6D %x61 %x6E %x64 %x61 %x74 %x6F %x72 %x79
 optionalKeyword     =  %x6F %x70 %x74 %x69 %x6F %x6E %x61 %x6C
 refineKeyword       =  %x72 %x65 %x66 %x69 %x6E %x65
 writetypeKeyword    =  %x77 %x72 %x69 %x74 %x65 %x74 %x79 %x70 %x65

 ;; End of ABNF
               ";
     };
     //
     //
     //

     snmp {

         node ccitt                       { oid 0;          };

         node   zeroDotZero {
             oid         0.0;
             description "A null value used for pointers.";
         };

         node iso                         { oid 1;          };
         node   org                       { oid iso.3;      };
         node     dod                     { oid org.6;      };
         node       internet              { oid dod.1;      };
         node         directory           { oid internet.1; };
         node         mgmt                { oid internet.2; };
         node           mib-2             { oid mgmt.1;     };
         node             transmission    { oid mib-2.10;   };
         node         experimental        { oid internet.3; };
         node         private             { oid internet.4; };
         node           enterprises       { oid private.1;  };
         node         security            { oid internet.5; };
         node         snmpV2              { oid internet.6; };
         node           snmpDomains       { oid snmpV2.1;   };
         node           snmpProxys        { oid snmpV2.2;   };
         node           snmpModules       { oid snmpV2.3;   };

         node joint-iso-ccitt             { oid 2;          };

         status          current;
         description
            "This set of nodes defines the core object
             identifier hierarchy";
         reference
            "RFC 2578, Section 2.";

     };

 };

6.  NMRG-SMING-SNMP

   The module NMRG-SMING-SNMP specified below defines derived types that
   are specific to the SNMP mapping.

module NMRG-SMING-SNMP {

    organization    "IRTF Network Management Research Group (NMRG)";

    contact         "IRTF Network Management Research Group (NMRG)
                     http://www.ibr.cs.tu-bs.de/projects/nmrg/

                     Frank Strauss
                     TU Braunschweig
                     Muehlenpfordtstrasse 23
                     38106 Braunschweig
                     Germany
                     Phone: +49 531 391 3266
                     EMail: strauss@ibr.cs.tu-bs.de

                     Juergen Schoenwaelder
                     International University Bremen
                     P.O. Box 750 561
                     28725 Bremen
                     Germany
                     Phone: +49 421 200 3587
                     EMail: j.schoenwaelder@iu-bremen.de";

    description     "Core type definitions for the SMIng SNMP mapping.
                     These definitions are based on RFC 2579 definitions
                     that are specific to the SNMP protocol and its
                     naming system.

                     Copyright (C) The Internet Society (2004).
                     All Rights Reserved.
                     This version of this module is part of
                     RFC 3781, see the RFC itself for full
                     legal notices.";

    revision {
        date        "2003-12-16";
        description "Initial version, published as RFC 3781.";
    };

    typedef TestAndIncr {
        type        Integer32 (0..2147483647);
        description
            "Represents integer-valued information used for atomic
             operations.  When the management protocol is used to
             specify that an object instance having this type is to
             be modified, the new value supplied via the management
             protocol must precisely match the value presently held by
             the instance.  If not, the management protocol set
             operation fails with an error of `inconsistentValue'.
             Otherwise, if the current value is the maximum value of
             2^31-1 (2147483647 decimal), then the value held by the
             instance is wrapped to zero; otherwise, the value held by
             the instance is incremented by one.  (Note that
             regardless of whether the management protocol set
             operation succeeds, the variable-binding in the request
             and response PDUs are identical.)

             The value of the SNMP access clause for objects having
             this type has to be `readwrite'.  When an instance of a
             columnar object having this type is created, any value
             may be supplied via the management protocol.

             When the network management portion of the system is re-
             initialized, the value of every object instance having
             this type must either be incremented from its value prior
             to the re-initialization, or (if the value prior to the
             re-initialization is unknown) be set to a
             pseudo-randomly generated value."; };

    typedef AutonomousType {
        type        Pointer;
        description
            "Represents an independently extensible type
             identification value.  It may, for example, indicate a
             particular OID sub-tree with further MIB definitions, or
             define a particular type of protocol or hardware.";
    };

    typedef VariablePointer {
        type        Pointer;
        description
            "A pointer to a specific object instance.  For example,
             sysContact.0 or ifInOctets.3.";
    };

    typedef RowPointer {
        type        Pointer;

        description
            "Represents a pointer to a conceptual row.  The value is
             the name of the instance of the first accessible columnar
             object in the conceptual row.

             For example, ifIndex.3 would point to the 3rd row in the
             ifTable (note that if ifIndex were not-accessible, then
             ifDescr.3 would be used instead).";
    };

    typedef RowStatus {
        type        Enumeration (active(1), notInService(2),
                        notReady(3), createAndGo(4),
                        createAndWait(5), destroy(6));
        description
        "The RowStatus type is used to manage the creation and
         deletion of conceptual rows, and is used as the type for the
         row status column of a conceptual row.

         The status column has six defined values:

             - `active', which indicates that the conceptual row is
             available for use by the managed device;

             - `notInService', which indicates that the conceptual
             row exists in the agent, but is unavailable for use by
             the managed device (see NOTE below);

             - `notReady', which indicates that the conceptual row
             exists in the agent, but is missing information
             necessary in order to be available for use by the
             managed device;

             - `createAndGo', which is supplied by a management
             station wishing to create a new instance of a
             conceptual row and to have its status automatically set
             to active, making it available for use by the managed
             device;

             - `createAndWait', which is supplied by a management
             station wishing to create a new instance of a
             conceptual row (but not make it available for use by
             the managed device); and,

             - `destroy', which is supplied by a management station
             wishing to delete all of the instances associated with
             an existing conceptual row.

         Whereas five of the six values (all except `notReady') may
         be specified in a management protocol set operation, only
         three values will be returned in response to a management
         protocol retrieval operation: `notReady', `notInService' or
         `active'.  That is, when queried, an existing conceptual row
         has only three states: it is either available for use by the
         managed device (the status column has value `active'); it is
         not available for use by the managed device, though the
         agent has sufficient information to make it so (the status
         column has value `notInService'); or, it is not available
         for use by the managed device, and an attempt to make it so
         would fail because the agent has insufficient information
         (the state column has value `notReady').

                                 NOTE WELL

             This textual convention may be used for a MIB table,
             irrespective of whether the values of that table's
             conceptual rows are able to be modified while it is
             active, or whether its conceptual rows must be taken
             out of service in order to be modified.  That is, it is
             the responsibility of the DESCRIPTION clause of the
             status column to specify whether the status column must
             not be `active' in order for the value of some other
             column of the same conceptual row to be modified.  If
             such a specification is made, affected columns may be
             changed by an SNMP set PDU if the RowStatus would not
             be equal to `active' either immediately before or after
             processing the PDU.  In other words, if the PDU also
             contained a varbind that would change the RowStatus
             value, the column in question may be changed if the
             RowStatus was not equal to `active' as the PDU was
             received, or if the varbind sets the status to a value
             other than 'active'.

         Also note that whenever any elements of a row exist, the
         RowStatus column must also exist.

         To summarize the effect of having a conceptual row with a
         column having a type of RowStatus, consider the following
         state diagram:

                                         STATE
              +--------------+-----------+-------------+-------------
              |      A       |     B     |      C      |      D
              |              |status col.|status column|
              |status column |    is     |      is     |status column
    ACTION    |does not exist|  notReady | notInService|  is active
--------------+--------------+-----------+-------------+-------------
set status    |noError    ->D|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndGo   |inconsistent- |           |             |
              |         Value|           |             |
--------------+--------------+-----------+-------------+-------------
set status    |noError  see 1|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndWait |wrongValue    |           |             |
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError
column to     |         Value|   entValue|             |
active        |              |           |             |
              |              |     or    |             |
              |              |           |             |
              |              |see 2   ->D|see 8     ->D|          ->D
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError   ->C
column to     |         Value|   entValue|             |
notInService  |              |           |             |
              |              |     or    |             |      or
              |              |           |             |
              |              |see 3   ->C|          ->C|see 6
--------------+--------------+-----------+-------------+-------------
set status    |noError       |noError    |noError      |noError   ->A
column to     |              |           |             |      or
destroy       |           ->A|        ->A|          ->A|see 7
--------------+--------------+-----------+-------------+-------------
set any other |see 4         |noError    |noError      |see 5
column to some|              |           |             |
value         |              |      see 1|          ->C|          ->D
--------------+--------------+-----------+-------------+-------------

         (1) go to B or C, depending on information available to the
         agent.

         (2) if other variable bindings included in the same PDU,
         provide values for all columns which are missing but
         required, then return noError and goto D.

         (3) if other variable bindings included in the same PDU,
         provide values for all columns which are missing but
         required, then return noError and goto C.

         (4) at the discretion of the agent, the return value may be
         either:

             inconsistentName: because the agent does not choose to
             create such an instance when the corresponding
             RowStatus instance does not exist, or

             inconsistentValue: if the supplied value is
             inconsistent with the state of some other MIB object's
             value, or

             noError: because the agent chooses to create the
             instance.

         If noError is returned, then the instance of the status
         column must also be created, and the new state is B or C,
         depending on the information available to the agent.  If
         inconsistentName or inconsistentValue is returned, the row
         remains in state A.

         (5) depending on the MIB definition for the column/table,
         either noError or inconsistentValue may be returned.

         (6) the return value can indicate one of the following
         errors:

             wrongValue: because the agent does not support
             createAndWait, or

             inconsistentValue: because the agent is unable to take
             the row out of service at this time, perhaps because it
             is in use and cannot be de-activated.

         (7) the return value can indicate the following error:

             inconsistentValue: because the agent is unable to
             remove the row at this time, perhaps because it is in
             use and cannot be de-activated.

         NOTE: Other processing of the set request may result in a
         response other than noError being returned, e.g.,
         wrongValue, noCreation, etc.

                          Conceptual Row Creation

         There are four potential interactions when creating a
         conceptual row: selecting an instance-identifier which is
         not in use; creating the conceptual row; initializing any
         objects for which the agent does not supply a default; and,
         making the conceptual row available for use by the managed
         device.

         Interaction 1: Selecting an Instance-Identifier

         The algorithm used to select an instance-identifier varies
         for each conceptual row.  In some cases, the instance-
         identifier is semantically significant, e.g., the
         destination address of a route, and a management station
         selects the instance-identifier according to the semantics.

         In other cases, the instance-identifier is used solely to
         distinguish conceptual rows, and a management station
         without specific knowledge of the conceptual row might
         examine the instances present in order to determine an
         unused instance-identifier.  (This approach may be used, but
         it is often highly sub-optimal; however, it is also a
         questionable practice for a naive management station to
         attempt conceptual row creation.)

         Alternately, the MIB module which defines the conceptual row
         might provide one or more objects which provide assistance
         in determining an unused instance-identifier.  For example,
         if the conceptual row is indexed by an integer-value, then
         an object having an integer-valued SYNTAX clause might be
         defined for such a purpose, allowing a management station to
         issue a management protocol retrieval operation.  In order
         to avoid unnecessary collisions between competing management
         stations, `adjacent' retrievals of this object should be
         different.

         Finally, the management station could select a pseudo-random
         number to use as the index.  In the event that this index
         was already in use and an inconsistentValue was returned in
         response to the management protocol set operation, the
         management station should simply select a new pseudo-random
         number and retry the operation.

         A MIB designer should choose between the two latter
         algorithms based on the size of the table (and therefore the
         efficiency of each algorithm).  For tables in which a large
         number of entries are expected, it is recommended that a MIB

         object be defined that returns an acceptable index for
         creation.  For tables with small numbers of entries, it is
         recommended that the latter pseudo-random index mechanism be
         used.

         Interaction 2: Creating the Conceptual Row

         Once an unused instance-identifier has been selected, the
         management station determines if it wishes to create and
         activate the conceptual row in one transaction or in a
         negotiated set of interactions.

         Interaction 2a: Creating and Activating the Conceptual Row

         The management station must first determine the column
         requirements, i.e., it must determine those columns for
         which it must or must not provide values.  Depending on the
         complexity of the table and the management station's
         knowledge of the agent's capabilities, this determination
         can be made locally by the management station.  Alternately,
         the management station issues a management protocol get
         operation to examine all columns in the conceptual row that
         it wishes to create.  In response, for each column, there
         are three possible outcomes:

             - a value is returned, indicating that some other
             management station has already created this conceptual
             row.  We return to interaction 1.

             - the exception `noSuchInstance' is returned,
             indicating that the agent implements the object-type
             associated with this column, and that this column in at
             least one conceptual row would be accessible in the MIB
             view used by the retrieval were it to exist. For those
             columns to which the agent provides read-create access,
             the `noSuchInstance' exception tells the management
             station that it should supply a value for this column
             when the conceptual row is to be created.

             - the exception `noSuchObject' is returned, indicating
             that the agent does not implement the object-type
             associated with this column or that there is no
             conceptual row for which this column would be
             accessible in the MIB view used by the retrieval.  As
             such, the management station can not issue any
             management protocol set operations to create an
             instance of this column.

         Once the column requirements have been determined, a
         management protocol set operation is accordingly issued.
         This operation also sets the new instance of the status
         column to `createAndGo'.

         When the agent processes the set operation, it verifies that
         it has sufficient information to make the conceptual row
         available for use by the managed device.  The information
         available to the agent is provided by two sources: the
         management protocol set operation which creates the
         conceptual row, and, implementation-specific defaults
         supplied by the agent (note that an agent must provide
         implementation-specific defaults for at least those objects
         which it implements as read-only).  If there is sufficient
         information available, then the conceptual row is created, a
         `noError' response is returned, the status column is set to
         `active', and no further interactions are necessary (i.e.,
         interactions 3 and 4 are skipped).  If there is insufficient
         information, then the conceptual row is not created, and the
         set operation fails with an error of `inconsistentValue'.
         On this error, the management station can issue a management
         protocol retrieval operation to determine if this was
         because it failed to specify a value for a required column,
         or, because the selected instance of the status column
         already existed.  In the latter case, we return to
         interaction 1.  In the former case, the management station
         can re-issue the set operation with the additional
         information, or begin interaction 2 again using
         `createAndWait' in order to negotiate creation of the
         conceptual row.

                                 NOTE WELL

             Regardless of the method used to determine the column
             requirements, it is possible that the management
             station might deem a column necessary when, in fact,
             the agent will not allow that particular columnar
             instance to be created or written.  In this case, the
             management protocol set operation will fail with an
             error such as `noCreation' or `notWritable'.  In this
             case, the management station decides whether it needs
             to be able to set a value for that particular columnar
             instance.  If not, the management station re-issues the
             management protocol set operation, but without setting

             a value for that particular columnar instance;
             otherwise, the management station aborts the row
             creation algorithm.

         Interaction 2b: Negotiating the Creation of the Conceptual
         Row

         The management station issues a management protocol set
         operation which sets the desired instance of the status
         column to `createAndWait'.  If the agent is unwilling to
         process a request of this sort, the set operation fails with
         an error of `wrongValue'.  (As a consequence, such an agent
         must be prepared to accept a single management protocol set
         operation, i.e., interaction 2a above, containing all of the
         columns indicated by its column requirements.) Otherwise,
         the conceptual row is created, a `noError' response is
         returned, and the status column is immediately set to either
         `notInService' or `notReady', depending on whether it has
         sufficient information to make the conceptual row available
         for use by the managed device.  If there is sufficient
         information available, then the status column is set to
         `notInService'; otherwise, if there is insufficient
         information, then the status column is set to `notReady'.
         Regardless, we proceed to interaction 3.

         Interaction 3: Initializing non-defaulted Objects

         The management station must now determine the column
         requirements.  It issues a management protocol get operation
         to examine all columns in the created conceptual row.  In
         the response, for each column, there are three possible
         outcomes:

             - a value is returned, indicating that the agent
             implements the object-type associated with this column
             and had sufficient information to provide a value.  For
             those columns to which the agent provides read-create
             access (and for which the agent allows their values to
             be changed after their creation), a value return tells
             the management station that it may issue additional
             management protocol set operations, if it desires, in
             order to change the value associated with this column.

             - the exception `noSuchInstance' is returned,
             indicating that the agent implements the object-type
             associated with this column, and that this column in at
             least one conceptual row would be accessible in the MIB
             view used by the retrieval were it to exist. However,

             the agent does not have sufficient information to
             provide a value, and until a value is provided, the
             conceptual row may not be made available for use by the
             managed device.  For those columns to which the agent
             provides read-create access, the `noSuchInstance'
             exception tells the management station that it must
             issue additional management protocol set operations, in
             order to provide a value associated with this column.

             - the exception `noSuchObject' is returned, indicating
             that the agent does not implement the object-type
             associated with this column or that there is no
             conceptual row for which this column would be
             accessible in the MIB view used by the retrieval.  As
             such, the management station can not issue any
             management protocol set operations to create an
             instance of this column.

         If the value associated with the status column is
         `notReady', then the management station must first deal with
         all `noSuchInstance' columns, if any.  Having done so, the
         value of the status column becomes `notInService', and we
         proceed to interaction 4.

         Interaction 4: Making the Conceptual Row Available

         Once the management station is satisfied with the values
         associated with the columns of the conceptual row, it issues
         a management protocol set operation to set the status column
         to `active'.  If the agent has sufficient information to
         make the conceptual row available for use by the managed
         device, the management protocol set operation succeeds (a
         `noError' response is returned).  Otherwise, the management
         protocol set operation fails with an error of
         `inconsistentValue'.

                                 NOTE WELL

             A conceptual row having a status column with value
             `notInService' or `notReady' is unavailable to the
             managed device.  As such, it is possible for the
             managed device to create its own instances during the
             time between the management protocol set operation
             which sets the status column to `createAndWait' and the
             management protocol set operation which sets the status
             column to `active'.  In this case, when the management
             protocol set operation is issued to set the status
             column to `active', the values held in the agent

             supersede those used by the managed device.

         If the management station is prevented from setting the
         status column to `active' (e.g., due to management station or
         network failure) the conceptual row will be left in the
         `notInService' or `notReady' state, consuming resources
         indefinitely.  The agent must detect conceptual rows that
         have been in either state for an abnormally long period of
         time and remove them.  It is the responsibility of the
         DESCRIPTION clause of the status column to indicate what an
         abnormally long period of time would be.  This period of time
         should be long enough to allow for human response time
         (including `think time') between the creation of the
         conceptual row and the setting of the status to `active'.  In
         the absence of such information in the DESCRIPTION clause, it
         is suggested that this period be approximately 5 minutes in
         length.  This removal action applies not only to newly-
         created rows, but also to previously active rows which are
         set to, and left in, the notInService state for a prolonged
         period exceeding that which is considered normal for such a
         conceptual row.

                         Conceptual Row Suspension

         When a conceptual row is `active', the management station
         may issue a management protocol set operation which sets the
         instance of the status column to `notInService'.  If the
         agent is unwilling to do so, the set operation fails with an
         error of `wrongValue' or `inconsistentValue'.
         Otherwise, the conceptual row is taken out of service, and a
         `noError' response is returned.  It is the responsibility of
         the DESCRIPTION clause of the status column to indicate
         under what circumstances the status column should be taken
         out of service (e.g., in order for the value of some other
         column of the same conceptual row to be modified).

                          Conceptual Row Deletion

         For deletion of conceptual rows, a management protocol set
         operation is issued which sets the instance of the status
         column to `destroy'.  This request may be made regardless of
         the current value of the status column (e.g., it is possible
         to delete conceptual rows which are either `notReady',
         `notInService' or `active'.) If the operation succeeds, then
         all instances associated with the conceptual row are
         immediately removed.";
    };

    typedef StorageType {
        type        Enumeration (other(1), volatile(2),
                        nonVolatile(3), permanent(4),
                        readOnly(5));
        description
            "Describes the memory realization of a conceptual row.  A
             row which is volatile(2) is lost upon reboot.  A row
             which is either nonVolatile(3), permanent(4) or
             readOnly(5), is backed up by stable storage.  A row which
             is permanent(4) can be changed but not deleted.  A row
             which is readOnly(5) cannot be changed nor deleted.

             If the value of an object with this syntax is either
             permanent(4) or readOnly(5), it cannot be modified.
             Conversely, if the value is either other(1), volatile(2)
             or nonVolatile(3), it cannot be modified to be
             permanent(4) or readOnly(5).  (All illegal modifications
             result in a 'wrongValue' error.)

             Every usage of this textual convention is required to
             specify the columnar objects which a permanent(4) row
             must at a minimum allow to be writable.";
    };

    typedef TDomain {
        type        Pointer;
        description
            "Denotes a kind of transport service.

             Some possible values, such as snmpUDPDomain, are defined
             in the SNMPv2-TM MIB module.  Other possible values are
             defined in other MIB modules."
        reference
            "The SNMPv2-TM MIB module is defined in RFC 3417."
    };

    typedef TAddressOrZero {
        type        OctetString (0..255);
        description
            "Denotes a transport service address.

             A TAddress value is always interpreted within the context
             of a TDomain value.  Thus, each definition of a TDomain
             value must be accompanied by a definition of a textual
             convention for use with that TDomain.  Some possible
             textual conventions, such as SnmpUDPAddress for
             snmpUDPDomain, are defined in the SNMPv2-TM MIB module.
             Other possible textual conventions are defined in other

             MIB modules.

             A zero-length TAddress value denotes an unknown transport
             service address."
        reference
            "The SNMPv2-TM MIB module is defined in RFC 3417."
    };

    typedef TAddress {
        type        TAddressOrZero (1..255);
        description
            "Denotes a transport service address.

             This type does not allow a zero-length TAddress value."
    };

};

7.  Security Considerations

   This document presents an extension of the SMIng data definition
   language which supports the mapping of SMIng data definitions so that
   they can be used with the SNMP management framework.  The language
   extension and the mapping itself has no security impact on the
   Internet.

8.  Acknowledgements

   Since SMIng started as a close successor of SMIv2, some paragraphs
   and phrases are directly taken from the SMIv2 specifications
   [RFC2578], [RFC2579], [RFC2580] written by Jeff Case, Keith
   McCloghrie, David Perkins, Marshall T.  Rose, Juergen Schoenwaelder,
   and Steven L. Waldbusser.

   The authors would like to thank all participants of the 7th NMRG
   meeting held in Schloss Kleinheubach from 6-8 September 2000, which
   was a major step towards the current status of this memo, namely
   Heiko Dassow, David Durham, Keith McCloghrie, and Bert Wijnen.

   Furthermore, several discussions within the SMING Working Group
   reflected experience with SMIv2 and influenced this specification at
   some points.

9. References

9.1.  Normative References

   [RFC3780]  Strauss, F. and J. Schoenwaelder, "SMIng - Next Generation
              Structure of Management Information", RFC 3780, May 2004.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

9.2.  Informative References

   [RFC3410]  Case, J., Mundy, R., Partain, D. and B. Stewart,
              "Introduction and Applicability Statements for Internet
              Standard Management Framework", RFC 3410, December 2002.

   [RFC2578]  McCloghrie, K., Perkins, D. and J. Schoenwaelder,
              "Structure of Management Information Version 2 (SMIv2)",
              STD 58, RFC 2578, April 1999.

   [RFC2579]  McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Textual
              Conventions for SMIv2", STD 59, RFC 2579, April 1999.

   [RFC2580]  McCloghrie, K., Perkins, D. and J. Schoenwaelder,
              "Conformance Statements for SMIv2", STD 60, RFC 2580,
              April 1999.

   [ASN1]     International Organization for Standardization,
              "Specification of Abstract Syntax Notation One (ASN.1)",
              International Standard 8824, December 1987.

   [RFC3159]  McCloghrie, K., Fine, M., Seligson, J., Chan, K., Hahn,
              S., Sahita, R., Smith, A. and F. Reichmeyer, "Structure of
              Policy Provisioning Information (SPPI)", RFC 3159, August
              2001.

   [IEEE754]  Institute of Electrical and Electronics Engineers, "IEEE
              Standard for Binary Floating-Point Arithmetic", ANSI/IEEE
              Standard 754-1985, August 1985.

   [RFC3418]  Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S.
              Waldbusser, "Management Information Base (MIB) for the
              Simple Network Management Protocol (SNMP)", STD 62, RFC
              3418, December 2002.

   [RFC3416]  Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S.
              Waldbusser, "Version 2 of the Protocol Operations for the
              Simple  Network Management Protocol (SNMP)", STD 62, RFC
              3416, December 2002.

Authors' Addresses

   Frank Strauss
   TU Braunschweig
   Muehlenpfordtstrasse 23
   38106 Braunschweig
   Germany

   Phone: +49 531 391 3266
   EMail: strauss@ibr.cs.tu-bs.de
   URI:   http://www.ibr.cs.tu-bs.de/

   Juergen Schoenwaelder
   International University Bremen
   P.O. Box 750 561
   28725 Bremen
   Germany

   Phone: +49 421 200 3587
   EMail: j.schoenwaelder@iu-bremen.de
   URI:   http://www.eecs.iu-bremen.de/

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