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Versions: (draft-schoenw-netmod-smi-yang) 00 01 02 03 04 05 RFC 6643

Network Working Group                                   J. Schoenwaelder
Internet-Draft                                         Jacobs University
Intended status: Standards Track                            July 1, 2011
Expires: January 2, 2012


            Translation of SMIv2 MIB Modules to YANG Modules
                     draft-ietf-netmod-smi-yang-01

Abstract

   YANG is a data modeling language used to model configuration and
   state data manipulated by the NETCONF protocol, NETCONF remote
   procedure calls, and NETCONF notifications.  The Structure of
   Management Information (SMIv2) defines fundamental data types, an
   object model, and the rules for writing and revising MIB modules for
   use with the SNMP protocol.  This document defines a translation of
   SMIv2 MIB modules into YANG modules, enabling read-only access to
   data objects defined in SMIv2 MIB modules via NETCONF.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

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

   This Internet-Draft will expire on January 2, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
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   Without obtaining an adequate license from the person(s) controlling
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   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.




































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Mapping of Special Types . . . . . . . . . . . . . . . . . . .  5
   3.  Module Prefix Generation . . . . . . . . . . . . . . . . . . .  6
   4.  Translation of SMIv2 Modules and SMIv2 IMPORT Clauses  . . . .  7
     4.1.  Example: IMPORTS of IF-MIB . . . . . . . . . . . . . . . .  8
   5.  Translation of the MODULE-IDENTITY Macro . . . . . . . . . . .  9
     5.1.  MODULE-IDENTITY Translation Rules  . . . . . . . . . . . .  9
     5.2.  Example: MODULE-IDENTITY of IF-MIB . . . . . . . . . . . . 10
   6.  Translation of the TEXTUAL-CONVENTION Macro  . . . . . . . . . 11
     6.1.  TEXTUAL-CONVENTION Translation Rules . . . . . . . . . . . 11
     6.2.  Example: OwnerString and InterfaceIndex of IF-MIB  . . . . 11
     6.3.  Example: IfDirection of the DIFFSERV-MIB . . . . . . . . . 12
   7.  Translation of OBJECT IDENTIFIER Assignments . . . . . . . . . 14
   8.  Translation of the OBJECT-TYPE Macro . . . . . . . . . . . . . 15
     8.1.  Scalar and Columnar Object Translation Rules . . . . . . . 15
     8.2.  Example: ifNumber and ifIndex of the IF-MIB  . . . . . . . 16
     8.3.  Non-Augmenting Conceptual Table Translation Rules  . . . . 16
     8.4.  Example: ifTable of the IF-MIB . . . . . . . . . . . . . . 18
     8.5.  Example: ifRcvAddressTable of the IF-MIB . . . . . . . . . 18
     8.6.  Augmenting Conceptual Tables Translation Rules . . . . . . 20
     8.7.  Example: ifXTable of the IF-MIB  . . . . . . . . . . . . . 21
   9.  Translation of the OBJECT-IDENTITY Macro . . . . . . . . . . . 22
     9.1.  OBJECT-IDENTITY Translation Rules  . . . . . . . . . . . . 22
     9.2.  Example: diffServTBParamSimpleTokenBucket of the
           DIFFSERV-MIB . . . . . . . . . . . . . . . . . . . . . . . 22
   10. Translation of the NOTIFICATION-TYPE Macro . . . . . . . . . . 23
     10.1. NOTIFICATION-TYPE Translation Rules  . . . . . . . . . . . 23
     10.2. Example: linkDown NOTIFICATION-TYPE of IF-MIB  . . . . . . 23
   11. YANG Language Extension Definition . . . . . . . . . . . . . . 26
   12. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 29
   13. Security Considerations  . . . . . . . . . . . . . . . . . . . 30
   14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
     14.1. Normative References . . . . . . . . . . . . . . . . . . . 31
     14.2. Informative References . . . . . . . . . . . . . . . . . . 31
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 32














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1.  Introduction

   This document describes an translation of SMIv2 [RFC2578], [RFC2579],
   [RFC2580] MIB modules into YANG [RFC6020] modules, enabling read-only
   access to data objects defined in SMIv2 MIB modules via NETCONF.  The
   mapping is illustrated by examples showing the translation of part of
   the IF-MIB [RFC2863] SMIv2 module and the DIFFSERV-MIB [RFC3289]
   SMIv2 module.

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






































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2.  Mapping of Special Types

   The SMIv2 base types and some well known derived textual-conventions
   are mapped to YANG types according to Table 1.  The mapping of the
   OCTET STRING depends on the context.  If an OCTET STRING type has an
   associated DISPLAY-HINT, then the corresponding YANG base type is the
   string type.  Otherwise, the binary type is used.  Similarly, the
   mapping of the INTEGER type depends on its usage as an enumeration or
   a 32-bit integral type.  Implementations are encouraged to provide
   options to handle situations where DISPLAY-HINTs are added during a
   revision of a module and backwards compatibility must be preserved.

                   Mapping of SMIv2 types to YANG types

   +------------+----------------+-----------------+-------------------+
   | SMIv2      | SMIv2 Type     | YANG Module     | YANG Type         |
   | Module     |                |                 |                   |
   +------------+----------------+-----------------+-------------------+
   | SNMPv2-SMI | INTEGER        |                 | enumeration       |
   | SNMPv2-SMI | INTEGER        |                 | int32             |
   | SNMPv2-SMI | Integer32      |                 | int32             |
   | SNMPv2-SMI | OCTET STRING   |                 | binary            |
   | SNMPv2-SMI | OCTET STRING   |                 | string            |
   | SNMPv2-SMI | OBJECT         | ietf-yang-types | object-identifier |
   |            | IDENTIFIER     |                 |                   |
   | SNMPv2-SMI | BITS           |                 | bits              |
   | SNMPv2-SMI | IpAddress      | ietf-inet-types | ipv4-address      |
   | SNMPv2-SMI | Counter32      | ietf-yang-types | counter32         |
   | SNMPv2-SMI | Gauge32        | ietf-yang-types | gauge32           |
   | SNMPv2-SMI | TimeTicks      | ietf-yang-types | timeticks         |
   | SNMPv2-SMI | Opaque         |                 | binary            |
   | SNMPv2-SMI | Counter64      | ietf-yang-types | counter64         |
   | SNMPv2-SMI | Unsigned32     |                 | uint32            |
   | SNMPv2-TC  | PhysAddress    | ietf-yang-types | phys-address      |
   | SNMPv2-TC  | MacAddress     | ietf-yang-types | mac-address       |
   | SNMPv2-TC  | TimeStamp      | ietf-yang-types | timestamp         |
   +------------+----------------+-----------------+-------------------+

                                  Table 1

   The mappings shown in Table 1 may impact the imports of the generated
   YANG module since some SMIv2 types and textual-conventions map to
   YANG types defined in the ietf-yang-types and ietf-inet-types YANG
   modules [RFC6021].  Implementations MUST add any additional imports
   required by the type mapping.






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3.  Module Prefix Generation

   The input of the prefix generation algorithm is a set of prefixes
   (usually derived from imported module names) and a specific module
   name to be converted into a prefix.  The algorithm described below
   produces a prefix for the given module name that is unique within the
   set of prefixes.

          Special prefixes for well known SMIv2 and YANG modules

                     +---------------------+--------+
                     | YANG / SMIv2 Module | Prefix |
                     +---------------------+--------+
                     | ietf-yang-types     | yang   |
                     | ietf-inet-types     | inet   |
                     | ietf-yang-smiv2     | smiv2  |
                     +---------------------+--------+

                                  Table 2

   o  First, some predefined translations mapping well known SMIv2 and
      YANG modules to short prefixes are tried (see Table 2).  If a
      fixed translation rule exists and leads to a conflict free prefix,
      then the fixed translation is used.

   o  Otherwise, prefixes are generated by tokenizing an SMIv2 module
      name, using hyphens as token separators.  The tokens derived from
      a module name are converted to lowercase characters.  The prefix
      then becomes the shortest sequence of token concatenated using
      hyphens as separators, which includes at least two token and which
      is unique among all prefixes used in the YANG module.

   In the worst case, the prefix derived from an SMIv2 module name
   becomes the SMIv2 module name translated to lower-case.  But on
   average, much shorter prefixes are generated.
















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4.  Translation of SMIv2 Modules and SMIv2 IMPORT Clauses

   SMIv2 modules are mapped to corresponding YANG modules.  The YANG
   module name MUST be the same as the SMIv2 module name.

   The YANG namespace MUST be constructed out of a constant prefix,
   which followed by the SMIv2 module name.  Since SMIv2 module names
   can be assumed to be unique (see Section 3 in [RFC2578]), the
   resulting YANG namespace is unique.  The registered prefix is
   urn:ietf:params:xml:ns:yang:smiv2:, see the IANA considerations in
   Section 12.

   The YANG prefix MAY be derived from the SMIv2 module name using the
   module prefix generation algorithm described in Section 3.  The YANG
   prefix is supposed to be short and it must be unique within the set
   of all prefixes used by a YANG module.  The algorithm described in
   Section 3 generates such prefixes.

   SMIv2 IMPORT clauses are translated to YANG import statements.  One
   major difference between the SMIv2 import mechanism and the YANG
   import mechanism is that SMIv2 IMPORT clauses import specific symbols
   from an SMIv2 module while the YANG import statement imports all
   symbols of the referenced YANG module.

                  SMIv2 imports that are ignored in YANG

                   +--------------+--------------------+
                   | SMIv2 Module | SMIv2 Symbol       |
                   +--------------+--------------------+
                   | SNMPv2-SMI   | MODULE-IDENTITY    |
                   | SNMPv2-SMI   | OBJECT-IDENTITY    |
                   | SNMPv2-SMI   | OBJECT-TYPE        |
                   | SNMPv2-SMI   | NOTIFICATION-TYPE  |
                   | SNMPv2-SMI   | mib-2              |
                   | SNMPv2-TC    | TEXTUAL-CONVENTION |
                   | SNMPv2-MIB   | snmpTraps          |
                   | SNMPv2-SMI   | * all symbols *    |
                   | SNMPv2-CONF  | * all symbols *    |
                   +--------------+--------------------+

                                  Table 3

   In order to produce correct and complete YANG import statements, the
   following rules MUST be used:

   o  Ignore all imports listed in Table 3.  Note that the modules
      SNMPv2-SMI and SNMPv2-CONF are completely ignored since all
      definitions in these modules are translated by translation rules



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      defined in this document.

   o  Add any imports required by the type translations according to the
      type mapping table.  This requires to consider all the types used
      in the translation unit in order to produce the imports.

   The generated import statements use the untranslated SMIv2 module
   names or the names of well-known YANG modules as their argument.  The
   import statement must contain a prefix statement.  The prefixes MAY
   be generated by applying the module prefix generation algorithm
   described in Section 3.

4.1.  Example: IMPORTS of IF-MIB

   The translation of the IF-MIB [RFC2863] leads to the YANG module
   frame and the import statements shown below.  The prefix is the
   translation of the SMIv2 module name IF-MIB to lowercase (consisting
   of two tokens and thus no further abbreviation).

     module IF-MIB {

       namespace "urn:ietf:params:xml:ns:yang:smiv2:IF-MIB";
       prefix "if-mib";

       import IANAifType-MIB      { prefix "ianaiftype-mib"; }
       import SNMPv2-TC           { prefix "smiv2-tc"; }
       import ietf-yang-types     { prefix "yang"; }
       import ietf-yang-smiv2     { prefix "smiv2"; }
     }






















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5.  Translation of the MODULE-IDENTITY Macro

   The SMIv2 requires an invocation of the MODULE-IDENTITY macro to
   provide contact and revision history for a MIB module.  The clauses
   of the SMIv2 MODULE-IDENTITY macro MUST be translated into YANG
   statements as detailed below.

5.1.  MODULE-IDENTITY Translation Rules

   o  The SMIv2 ORGANIZATION clause is mapped to the YANG organization
      statement.

   o  The SMIv2 CONTACT-INFO clause is mapped to the YANG contact
      statement.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  Each SMIv2 REVISION clause is mapped to a YANG revision statement.
      The revision is identified by the date argument of the SMIv2
      REVISION clause.  DESCRIPTION sub-clauses of REVISION clauses are
      mapped to corresponding description statement nested in revision
      clauses.

   o  The SMIv2 LAST-UPDATED clause is ignored if the associated date
      matches a REVISION clause.  Otherwise, an additional revision
      statement is generated.

   o  The name of the MODULE-IDENTITY macro invocation is used to
      generate a top-level container statement.  This container MUST be
      config false.

   o  The object identifier value of the invocation of the SMIv2 MODULE-
      IDENTITY MAY be translated into an smiv2:oid statement contained
      in the container representing the MODULE-IDENTITY macro
      invocation, see the YANG extension defined in Section 11.

   While all proper SMIv2 modules must have exactly one MODULE-IDENTITY
   macro invocation, there are a few notable exceptions.  The modules
   defining the SMIv2 language (i.e., the SNMPv2-SMI, SNMPv2-TC, and
   SNMPv2-CONF modules) do not invoke the MODULE-IDENTITY macro.
   Furthermore, SMIv2 modules generated from SMIv1 modules may miss an
   invocation of the MODULE-IDENTITY macro as well.  In such cases, it
   is preferable to not generate organization, contact, description, and
   revision statements.






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5.2.  Example: MODULE-IDENTITY of IF-MIB

   The translation of the MODULE-IDENTITY of the IF-MIB [RFC2863] leads
   to the following YANG statements:

     organization
      "IETF Interfaces MIB Working Group";

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

       408-526-5260
       kzm@cisco.com";

     description
      "The MIB module to describe generic objects for network
       interface sub-layers.  This MIB is an updated version of
       MIB-II's ifTable, and incorporates the extensions defined in
       RFC 1229.";

     revision "2000-06-14" {
       description
        "Clarifications agreed upon by the Interfaces MIB WG, and
         published as RFC 2863.";
     }
     revision "1996-02-28" {
       description
        "Revisions made by the Interfaces MIB WG, and published in
         RFC 2233.";
     }
     revision "1993-11-08" {
       description
        "Initial revision, published as part of RFC 1573.";
     }

     container ifMIB {
       config false;
       description
        "[Automatically generated top-level container.]";
       smiv2:oid "1.3.6.1.2.1.31";
     }






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6.  Translation of the TEXTUAL-CONVENTION Macro

   The SMIv2 uses invocations of the TEXTUAL-CONVENTION macro to define
   new types derived from the SMIv2 base types.  Invocations of the
   TEXTUAL-CONVENTION macro MUST be translated into YANG typedef
   statements as detailed below.

6.1.  TEXTUAL-CONVENTION Translation Rules

   The name of the TEXTUAL-CONVENTION macro invocation is used as the
   name of the generated typedef statement.  The clauses of the SMIv2
   TEXTUAL-CONVENTION macro are mapped to YANG statements embedded in
   the typedef statement as follows:

   o  The SMIv2 DISPLAY-HINT clause is used to determine the type
      mapping of types derived form the OCTET STRING type as explained
      in Section 2.  Furthermore, the DISPLAY-HINT value MAY be used to
      generate a regular expression for the YANG pattern statement
      within the type statement.

   o  The SMIv2 DISPLAY-HINT MAY be translated into an smiv2:display-
      hint statement, see the YANG extension defined in Section 11.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The SMIv2 SYNTAX clause is mapped to the YANG type statement.
      SMIv2 range restrictions are mapped to YANG range statements while
      SMIv2 length restrictions are mapped to YANG length statements.
      SMIv2 INTEGER enumerations and SMIv2 BITS are mapped to YANG enum
      / value and bit / position statements.

   This translation assumes that labels of named numbers and named bits
   do not change when an SMIv2 module is revised.  This is consistent
   with the clarification of the SMIv2 module revision rules in Section
   4.9 of [RFC4181].

6.2.  Example: OwnerString and InterfaceIndex of IF-MIB

   The translation of the OwnerString and InterfaceIndex textual-
   conventions of the IF-MIB [RFC2863] are shown below.



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     typedef OwnerString {
       type string {
         length "0..255";
         pattern '\p{IsBasicLatin}{0,255}';
       }
       status deprecated;
       description
        "This data type is used to model an administratively
         assigned name of the owner of a resource.  This information
         is taken from the NVT ASCII character set.  It is suggested
         that this name contain one or more of the following: ASCII
         form of the manager station's transport address, management
         station name (e.g., domain name), network management
         personnel's name, location, or phone number.  In some cases
         the agent itself will be the owner of an entry.  In these
         cases, this string shall be set to a string starting with
         'agent'.";
       smiv2:display-hint "255a";
     }

     typedef InterfaceIndex {
       type int32 {
         range "1..2147483647";
       }
       description
        "A unique value, greater than zero, for each interface or
         interface sub-layer in the managed system.  It is
         recommended that values are assigned contiguously starting
         from 1.  The value for each interface sub-layer must remain
         constant at least from one re-initialization of the entity's
         network management system to the next re-initialization.";
       smiv2:display-hint "d";
     }

6.3.  Example: IfDirection of the DIFFSERV-MIB

   The translation of the IfDirection textual-convention of the
   DIFFSERV-MIB [RFC3289] is shown below.













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   typedef IfDirection {
     type enumeration {
       enum inbound  { value 1; }
       enum outbound { value 2; }
     }
     description
      "IfDirection specifies a direction of data travel on an
       interface. 'inbound' traffic is operated on during reception from
       the interface, while 'outbound' traffic is operated on prior to
       transmission on the interface.";
   }








































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7.  Translation of OBJECT IDENTIFIER Assignments

   The SMIv2 uses OBJECT IDENTIFIER assignments to introduce names for
   intermediate nodes in the OBJECT IDENTIFIER tree.  OBJECT IDENTIFIER
   assignments are not translated into YANG statements.














































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8.  Translation of the OBJECT-TYPE Macro

   The SMIv2 uses the OBJECT-TYPE macro to define objects and the
   structure of conceptual tables.  Objects exist either as scalars
   (exactly one instance within an SNMP context) or columnar objects
   within conceptual tables (zero or multiple instances within an SNMP
   context).  A number of auxiliary objects define the index (key) of a
   conceptual table.  Furthermore, conceptual tables can be augmented by
   other conceptual tables.  All these differences must be taken into
   account when translating SMIv2 OBJECT-TYPE macro invocations to YANG.
   Invocations of the OBJECT-TYPE macro MUST be translated into YANG
   statements as detailed below.

8.1.  Scalar and Columnar Object Translation Rules

   SMIv2 OBJECT-TYPE macro invocations defining scalars or columnar
   objects with a MAX-ACCESS of "not-accessible", "read-only",
   "read-write" and ""read-create" are translated to YANG leaf
   statements.  The name of the leaf is the name associated with the
   SMIv2 OBJECT-TYPE macro invocation.  SMIv2 OBJECT-TYPE macro
   invocations with a MAX-ACCESS of "accessible-for-notify" are not
   translated to YANG data tree leafs but instead into YANG notification
   leafs.

   All leaf statements for scalar objects are created in the top-level
   container representing the SMIv2 module, see Section 5.1.  The leaf
   statements representing columnar objects are created in the list
   representing a conceptual row, see Section 8.3.

   o  The SMIv2 SYNTAX clause is mapped to the YANG type statement.
      SMIv2 range restrictions are mapped to YANG range statements while
      SMIv2 length restrictions are mapped to YANG length statements.
      SMIv2 INTEGER enumerations and SMIv2 BITS are mapped to YANG enum
      / value and bit / position statements.

   o  The SMIv2 UNITS clause is mapped to the YANG units statement.

   o  The SMIv2 MAX-ACCESS MAY be translated into an smiv2:max-access
      statement, see the YANG extension defined in Section 11.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.





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   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The value of the SMIv2 OBJECT-TYPE macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.

   This translation assumes that labels of named numbers and named bits
   do not change when an SMIv2 module is revised.  This is consistent
   with the clarification of the SMIv2 module revision rules in Section
   4.9 of [RFC4181].

8.2.  Example: ifNumber and ifIndex of the IF-MIB

   The translations of the ifNumber scalar object and the ifIndex
   columnar object of the IF-MIB [RFC2863] are shown below.

     leaf ifNumber {
       type int32;
       description
        "The number of network interfaces (regardless of their
         current state) present on this system.";
       smiv2:max-access "read-only";
       smiv2:oid "1.3.6.1.2.1.2.1";
     }

     leaf ifIndex {
       type if-mib:InterfaceIndex;
       description
        "A unique value, greater than zero, for each interface.  It
         is recommended that values are assigned contiguously
         starting from 1.  The value for each interface sub-layer
         must remain constant at least from one re-initialization of
         the entity's network management system to the next re-
         initialization.";
       smiv2:max-access "read-only";
       smiv2:oid "1.3.6.1.2.1.2.2.1.1";
     }

8.3.  Non-Augmenting Conceptual Table Translation Rules

   An OBJECT-TYPE macro invocation defining a non-augmenting conceptual
   table is translated to a YANG container statement using the name of
   the OBJECT-TYPE macro invocation.  This container is created in the
   top-level container representing the SMIv2 module.  The clauses of
   the macro are translated as follows:





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   o  The SMIv2 SYNTAX clause is ignored

   o  The SMIv2 UNITS clause is ignored.

   o  The SMIv2 MAX-ACCESS clause is ignored.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The value of the SMIv2 OBJECT-TYPE macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.

   An OBJECT-TYPE macro invocation defining a conceptual row is
   translated to a YANG list statement.  It is contained in the YANG
   container representing the conceptual table.  The generated list uses
   the name of the row OBJECT-TYPE macro invocation.  The clauses of the
   OBJECT-TYPE macro are translated as follows:

   o  The SMIv2 SYNTAX clause is ignored.

   o  The SMIv2 UNITS clause is ignored.

   o  The SMIv2 MAX-ACCESS clause is ignored.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The SMIv2 INDEX clause is mapped to the YANG key clause listing
      the columnar objects forming the key of the YANG list.

   o  The value of the SMIv2 OBJECT-TYPE macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.



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   Within the list statement, YANG leaf statements are created for
   columnar objects as described in Section 8.1.  For objects listed in
   the SMIv2 INDEX clause that are not part of the conceptual table
   itself, YANG leaf statements of type leafref pointing to the
   referenced definition are created.

8.4.  Example: ifTable of the IF-MIB

   The translation of the definition of the ifTable of the IF-MIB
   [RFC2863] is shown below.

     container ifTable {
       config false;
       description
        "A list of interface entries.  The number of entries is
         given by the value of ifNumber.";
       smiv2:oid "1.3.6.1.2.1.2.2";

       list ifEntry {
         key "ifIndex";
         description
          "An entry containing management information applicable to a
           particular interface.";
         smiv2:oid "1.3.6.1.2.1.2.2.1";

         leaf ifIndex {
           type if-mib:InterfaceIndex;
           description
            "A unique value, greater than zero, for each interface.  It
             is recommended that values are assigned contiguously
             starting from 1.  The value for each interface sub-layer
             must remain constant at least from one re-initialization of
             the entity's network management system to the next re-
             initialization.";
           smiv2:max-access "read-only";
           smiv2:oid "1.3.6.1.2.1.2.2.1.1";
         }

         // ...
       }
     }

8.5.  Example: ifRcvAddressTable of the IF-MIB

   The translation of the definition of the ifRcvAddressTable of the IF-
   MIB [RFC2863] is shown below.

     container ifRcvAddressTable {



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       description
        "This table contains an entry for each address (broadcast,
         multicast, or uni-cast) for which the system will receive
         packets/frames on a particular interface, except as follows:

         - for an interface operating in promiscuous mode, entries
         are only required for those addresses for which the system
         would receive frames were it not operating in promiscuous
         mode.

         - for 802.5 functional addresses, only one entry is
         required, for the address which has the functional address
         bit ANDed with the bit mask of all functional addresses for
         which the interface will accept frames.

         A system is normally able to use any unicast address which
         corresponds to an entry in this table as a source address.";
       smiv2:oid "1.3.6.1.2.1.31.1.4";

       list ifRcvAddressEntry {
         key "ifIndex ifRcvAddressAddress";
         description
          "A list of objects identifying an address for which the
           system will accept packets/frames on the particular
           interface identified by the index value ifIndex.";
         smiv2:oid "1.3.6.1.2.1.31.1.4.1";

         leaf ifIndex {
           type leafref {
             path "/if-mib:ifMIB/if-mib:ifTable" +
                  "/if-mib:ifEntry/if-mib:ifIndex";
           }
           description
            "[Automatically generated leaf for a foreign index.]";
         }

         leaf ifRcvAddressAddress {
           type yang:phys-address;
           description
            "An address for which the system will accept packets/frames
             on this entry's interface.";
           smiv2:max-access "not-accessible";
           smiv2:oid "1.3.6.1.2.1.31.1.4.1.1";
         }

         // ...
       }
     }



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8.6.  Augmenting Conceptual Tables Translation Rules

   An OBJECT-TYPE macro invocation defining an augmenting conceptual
   table is not translated to a YANG statement.  The name assigned by
   the OBJECT-TYPE macro invocation to the augmenting conceptual table
   MAY be captured in a comment.  The clauses of the macro are
   translated as follows:

   o  The SMIv2 SYNTAX clause is ignored.

   o  The SMIv2 UNITS clause is ignored.

   o  The SMIv2 MAX-ACCESS clause is ignored.

   o  The SMIv2 STATUS clause is ignored.

   o  The SMIv2 DESCRIPTION clause MAY be captured in a comment.

   o  The SMIv2 REFERENCE clause MAY be captured in a comment.

   o  The value of the SMIv2 OBJECT-TYPE macro invocation MAY be
      captured in a comment.

   An OBJECT-TYPE macro invocation defining a conceptual row
   augmentation is translated to a YANG augment statement using the path
   to the augmented table as its argument.  The clauses of the OBJECT-
   TYPE macro are translated as follows:

   o  The SMIv2 SYNTAX clause is ignored.

   o  The SMIv2 UNITS clause is ignored.

   o  The SMIv2 MAX-ACCESS clause is ignored.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The value of the SMIv2 OBJECT-TYPE macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.




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   Within the augment statement, YANG leaf statements are created as
   described in Section 8.1.

8.7.  Example: ifXTable of the IF-MIB

   The translation of the definition of the ifXTable of the IF-MIB
   [RFC2863] is shown below.

     /*
      * ifXTable (1.3.6.1.2.1.31.1.1)
      *
      * A list of interface entries.  The number of entries is
      * given by the value of ifNumber.  This table contains
      * additional objects for the interface table.
      */

     augment "/if-mib:ifMIB/if-mib:ifTable/if-mib:ifEntry" {
       description
        "An entry containing additional management information
         applicable to a particular interface.";
       smiv2:oid "1.3.6.1.2.1.31.1.1.1";

       leaf ifName {
         type snmpv2-tc:DisplayString;
         description
          "The textual name of the interface.  The value of this
           object should be the name of the interface as assigned by
           the local device and should be suitable for use in commands
           entered at the device's `console'.  This might be a text
           name, such as `le0' or a simple port number, such as `1',
           depending on the interface naming syntax of the device.  If
           several entries in the ifTable together represent a single
           interface as named by the device, then each will have the
           same value of ifName.  Note that for an agent which responds
           to SNMP queries concerning an interface on some other
           (proxied) device, then the value of ifName for such an
           interface is the proxied device's local name for it.

           If there is no local name, or this object is otherwise not
           applicable, then this object contains a zero-length string.";
         smiv2:max-access "read-only";
         smiv2:oid "1.3.6.1.2.1.31.1.1.1.1";
       }

       // ...
     }





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9.  Translation of the OBJECT-IDENTITY Macro

   The SMIv2 uses invocations of the OBJECT-IDENTITY macro to define
   information about an OBJECT IDENTIFIER assignment.  Invocations of
   the OBJECT-IDENTITY macro MUST be translated into YANG identity
   statements as detailed below.

9.1.  OBJECT-IDENTITY Translation Rules

   The name of the OBJECT-IDENTITY macro invocation is used as the name
   of the generated identity statement.  The generated identity
   statement uses the smiv2:object-identity defined in Section 11 as its
   base.  The clauses of the SMIv2 OBJECT-IDENTITY macro are mapped to
   YANG statements as follows:

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The value of the SMIv2 OBJECT-IDENTITY macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.

9.2.  Example: diffServTBParamSimpleTokenBucket of the DIFFSERV-MIB

   The translation of the diffServTBParamSimpleTokenBucket of the
   DIFFSERV-MIB [RFC3289] is shown below.

     identity diffServTBParamSimpleTokenBucket {
       base "smiv2:object-identity";
       description
        "Two Parameter Token Bucket Meter as described in the Informal
         Differentiated Services Model section 5.2.3.";
       smiv2:oid "1.3.6.1.2.1.97.3.1.1";
     }










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10.  Translation of the NOTIFICATION-TYPE Macro

   The SMIv2 provides the NOTIFICATION-TYPE macro to define event
   notifications.  YANG provides the notification statement for the same
   purpose.  Invocations of the NOTIFICATION-TYPE macro MUST be
   translated into YANG notification statements as detailed below.

10.1.  NOTIFICATION-TYPE Translation Rules

   The name of the NOTIFICATION-TYPE macro invocation is used as the
   name of the generated notification statement.  The clauses of the
   NOTIFICATION-TYPE macro are mapped to YANG statements embedded in the
   notification statement as follows.

   o  The SMIv2 OBJECTS clause is mapped to a sequence of YANG
      containers.  For each object listed in the OBJECTS clause value, a
      YANG container statement is generated.  The name of this container
      is the string "object-<n>", where <n> is the position of the
      object in the value of the OBJECTS clause (first element has
      position 1).  If the current object belongs to a conceptual table,
      then a sequence of leaf statements is generated for each INDEX
      object of the conceptual table.  These leafs are named after the
      INDEX objects and of type leafref.  Finally, a leaf statement is
      generated named after the current object.  If the current object
      has a MAX-ACCESS of "read-only", "read-write" or ""read-create",
      then the generated leaf is of type leafref.  Otherwise, if the
      current object has a MAX-ACCESS of "accessible-for-notify", then a
      leaf is generated, following the itemized steps in Section 8.1.

   o  The SMIv2 STATUS clause is mapped to the YANG status statement.
      The generation of the YANG status statement is skipped if the
      value of the STATUS clause is current.

   o  The SMIv2 DESCRIPTION clause is mapped to the YANG description
      statement.

   o  The SMIv2 REFERENCE clause is mapped to the YANG reference
      statement.

   o  The value of the SMIv2 NOTIFICATION-TYPE macro invocation MAY be
      translated into an smiv2:oid statement, see the YANG extension
      defined in Section 11.

10.2.  Example: linkDown NOTIFICATION-TYPE of IF-MIB

   The translation of the linkDown notification of the IF-MIB [RFC2863]
   is shown below.




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   notification linkDown {
     description
      "A linkDown trap signifies that the SNMP entity, acting in
       an agent role, has detected that the ifOperStatus object for
       one of its communication links is about to enter the down
       state from some other state (but not from the notPresent
       state).  This other state is indicated by the included value
       of ifOperStatus.";
     smiv2:oid "1.3.6.1.6.3.1.1.5.3";

     container object-1 {
       description
        "[Automatically generated container for a notification object.";

       leaf ifIndex {
         type leafref {
           path "/if-mib:ifMIB/if-mib:ifTable" +
                "/if-mib:ifEntry/if-mib:ifIndex";
         }
         description
          "[Automatically generated leaf for a notification object.]";
       }
     }

     container object-2 {
       description
        "[Automatically generated container for a notification object.";

       leaf ifIndex {
         type leafref {
           path "/if-mib:ifMIB/if-mib:ifTable" +
                "/if-mib:ifEntry/if-mib:ifIndex";
         }
         description
          "[Automatically generated leaf for a notification object
            index.]";
       }
       leaf ifAdminStatus {
         type leafref {
           path "/if-mib:ifMIB/if-mib:ifTable" +
                "/if-mib:ifEntry/if-mib:ifAdminStatus";
         }
         description
          "[Automatically generated leaf for a notification object.]";
       }
     }

     container object-3 {



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       description
        "[Automatically generated container for a notification object.";

       leaf ifIndex {
         type leafref {
           path "/if-mib:ifMIB/if-mib:ifTable" +
                "/if-mib:ifEntry/if-mib:ifIndex";
         }
         description
          "[Automatically generated leaf for a notification object
            index.]";
       }
       leaf ifOperStatus {
         type leafref {
           path "/if-mib:ifMIB/if-mib:ifTable" +
                "/if-mib:ifEntry/if-mib:ifOperStatus";
         }
         description
          "[Automatically generated leaf for a notification object.]";
       }
     }
   }





























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11.  YANG Language Extension Definition

   This section defines some YANG extension statements that can be used
   to capture some information present in SMIv2 modules that is not
   translated into core YANG statements.  The YANG module references
   [RFC2578] and [RFC2579].

   <CODE BEGINS> file "ietf-yang-smiv2@2011-07-01.yang"

module ietf-yang-smiv2 {

  namespace "urn:ietf:params:xml:ns:yang:ietf-yang-smiv2";
  prefix "smiv2";

  organization
   "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

  contact
   "WG Web:   <http://tools.ietf.org/wg/netmod/>
    WG List:  <mailto:netmod@ietf.org>

    WG Chair: David Kessens
              <mailto:david.kessens@nsn.com>

    WG Chair: Juergen Schoenwaelder
              <mailto:j.schoenwaelder@jacobs-university.de>

    Editor:   Juergen Schoenwaelder
              <mailto:j.schoenwaelder@jacobs-university.de>";

  description
   "This module defines YANG extensions that are used to translate
    SMIv2 concepts into YANG.

    Copyright (c) 2011 IETF Trust and the persons identified as
    authors of the code.  All rights reserved.

    Redistribution and use in source and binary forms, with or
    without modification, is permitted pursuant to, and subject
    to the license terms contained in, the Simplified BSD License
    set forth in Section 4.c of the IETF Trust's Legal Provisions
    Relating to IETF Documents
    (http://trustee.ietf.org/license-info).

    This version of this YANG module is part of RFC XXXX; see
    the RFC itself for full legal notices.";
    // RFC Ed.: replace XXXX with actual RFC number and remove this note




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  // RFC Ed.: please update the date to the date of publication
  revision 2011-07-01 {
    description
     "Initial revision.";
    reference
     "RFC XXXX: Translation of SMIv2 MIB Modules to YANG Modules";
    // RFC Ed.: replace XXXX with actual RFC number and remove this note
  }

  identity object-identity {
    description
     "Base identity for all SMIv2 OBJECT-IDENTITYs.";
  }

  extension oid {
    argument "value";
    description
     "The oid statement takes as an argument the object identifier
      assigned to an SMIv2 definition. The object identifier value
      is written in decimal dotted notation.";
    reference
     "RFC2578: Structure of Management Information Version 2 (SMIv2)";
  }

  extension display-hint {
    argument "format";
    description
     "The display-hint statement takes as an argument the DISPLAY-HINT
      assigned to an SMIv2 textual convention.";
    reference
     "RFC2579: Textual Conventions for SMIv2";
  }

  extension max-access {
    argument "access";
    description
     "The max-access statement takes as an argument the MAX-ACCESS
      assigned to an SMIv2 object definition";
    reference
     "RFC2578: Structure of Management Information Version 2 (SMIv2)";
  }

  extension defval {
    argument "value";
    description
     "The defval statement takes as an argument a default value defined
      by an SMIv2 DEFVAL clause.";
    reference



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     "RFC2578: Structure of Management Information Version 2 (SMIv2)";
  }

  extension alias {
    argument "descriptor"
    description
     "The alias statement introduces an SMIv2 descriptor. The body of
      the alias statement is expected to contain an oid statement that
      provides the numeric OID associated with the descriptor.";
    reference
     "RFC2578: Structure of Management Information Version 2 (SMIv2)";
  }

}

   <CODE ENDS>



































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12.  IANA Considerations

   This document registers two URIs in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registrations have
   been made.

     URI: urn:ietf:params:xml:ns:yang:ietf-yang-smiv2

     Registrant Contact: The NETMOD WG of the IETF.

     XML: N/A, the requested URI is an XML namespace.


     URI: urn:ietf:params:xml:ns:yang:smiv2

     Registrant Contact: The NETMOD WG of the IETF.

     XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

     name:         ietf-yang-smiv2
     namespace:    urn:ietf:params:xml:ns:yang:ietf-yang-smiv2
     prefix:       smiv2
     reference:    RFC XXXX

























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13.  Security Considerations

   This document defines a translation of SMIv2 MIB modules into YANG
   modules, enabling read-only access to data objects defined in SMIv2
   MIB modules via NETCONF.  The translation itself has no security
   impact on the Internet.

   Users of translated SMIv2 models that have been published as RFCs
   should consult the security considerations of the respective RFCs.
   In addition, the security considerations for the NETCONF protocol
   [RFC6241] should be consulted to understand how NETCONF protects
   potentially sensitive information.







































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14.  References

14.1.  Normative References

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

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

   [RFC2579]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Textual Conventions for SMIv2",
              STD 58, RFC 2579, April 1999.

   [RFC2580]  McCloghrie, K., Perkins, D., and J. Schoenwaelder,
              "Conformance Statements for SMIv2", STD 58, RFC 2580,
              April 1999.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6021]  Schoenwaelder, J., "Common YANG Data Types", RFC 6021,
              October 2010.

14.2.  Informative References

   [RFC2863]  McCloghrie, K. and F. Kastenholz, "The Interfaces Group
              MIB", RFC 2863, June 2000.

   [RFC3289]  Baker, F., Chan, K., and A. Smith, "Management Information
              Base for the Differentiated Services Architecture",
              RFC 3289, May 2002.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC4181]  Heard, C., "Guidelines for Authors and Reviewers of MIB
              Documents", BCP 111, RFC 4181, September 2005.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, June 2011.







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Author's Address

   Juergen Schoenwaelder
   Jacobs University

   Email: j.schoenwaelder@jacobs-university.de













































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