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Network Working Group                                           M. RoseRequest for Comments: 1212            Performance Systems International                                                          K. McCloghrie                                                     Hughes LAN Systems                                                                Editors                                                             March 1991Concise MIB DefinitionsStatus of this Memo   This memo defines a format for producing MIB modules.  This RFC   specifies an IAB standards track document for the Internet community,   and requests discussion and suggestions for improvements.  Please   refer to the current edition of the "IAB Official Protocol Standards"   for the standardization state and status of this protocol.   Distribution of this memo is unlimited.Table of Contents1. Abstract..............................................22. Historical Perspective ...............................23. Columnar Objects .....................................33.1 Row Deletion ........................................43.2 Row Addition ........................................44. Defining Objects .....................................54.1 Mapping of the OBJECT-TYPE macro ....................74.1.1 Mapping of the SYNTAX clause ......................74.1.2 Mapping of the ACCESS clause ......................84.1.3 Mapping of the STATUS clause ......................84.1.4 Mapping of the DESCRIPTION clause .................84.1.5 Mapping of the REFERENCE clause ...................84.1.6 Mapping of the INDEX clause .......................84.1.7 Mapping of the DEFVAL clause ......................104.1.8 Mapping of the OBJECT-TYPE value ..................114.2 Usage Example .......................................115. Appendix: DE-osifying MIBs ...........................135.1 Managed Object Mapping ..............................145.1.1 Mapping to the SYNTAX clause ......................155.1.2 Mapping to the ACCESS clause ......................155.1.3 Mapping to the STATUS clause ......................155.1.4 Mapping to the DESCRIPTION clause .................155.1.5 Mapping to the REFERENCE clause ...................165.1.6 Mapping to the INDEX clause .......................165.1.7 Mapping to the DEFVAL clause ......................165.2 Action Mapping ......................................165.2.1 Mapping to the SYNTAX clause ......................165.2.2 Mapping to the ACCESS clause ......................16SNMP Working Group                                              [Page 1]

RFC 1212                Concise MIB Definitions               March 19915.2.3 Mapping to the STATUS clause ......................165.2.4 Mapping to the DESCRIPTION clause .................165.2.5 Mapping to the REFERENCE clause ...................166. Acknowledgements .....................................177. References ...........................................188. Security Considerations...............................199. Authors' Addresses....................................191.  Abstract   This memo describes a straight-forward approach toward producing   concise, yet descriptive, MIB modules.  It is intended that all   future MIB modules be written in this format.2.  Historical Perspective   As reported inRFC 1052, IAB Recommendations for the Development of   Internet Network Management Standards [1], a two-prong strategy for   network management of TCP/IP-based internets was undertaken.  In the   short-term, the Simple Network Management Protocol (SNMP), defined inRFC 1067, was to be used to manage nodes in the Internet community.   In the long-term, the use of the OSI network management framework was   to be examined.  Two documents were produced to define the management   information:RFC 1065, which defined the Structure of Management   Information (SMI), andRFC 1066, which defined the Management   Information Base (MIB).  Both of these documents were designed so as   to be compatible with both the SNMP and the OSI network management   framework.   This strategy was quite successful in the short-term: Internet-based   network management technology was fielded, by both the research and   commercial communities, within a few months.  As a result of this,   portions of the Internet community became network manageable in a   timely fashion.   As reported inRFC 1109, Report of the Second Ad Hoc Network   Management Review Group [2], the requirements of the SNMP and the OSI   network management frameworks were more different than anticipated.   As such, the requirement for compatibility between the SMI/MIB and   both frameworks was suspended.  This action permitted the operational   network management framework, based on the SNMP, to respond to new   operational needs in the Internet community by producing MIB-II.   In May of 1990, the core documents were elevated to "Standard   Protocols" with "Recommended" status.  As such, the Internet-standard   network management framework consists of: Structure and   Identification of Management Information for TCP/IP-based internets,RFC 1155 [3], which describes how managed objects contained in theSNMP Working Group                                              [Page 2]

RFC 1212                Concise MIB Definitions               March 1991   MIB are defined; Management Information Base for Network Management   of TCP/IP-based internets, which describes the managed objects   contained in the MIB,RFC 1156 [4]; and, the Simple Network   Management Protocol,RFC 1157 [5], which defines the protocol used to   manage these objects.  Consistent with the IAB directive to produce   simple, workable systems in the short-term, the list of managed   objects defined in the Internet-standard MIB was derived by taking   only those elements which are considered essential.  However, the SMI   defined three extensibility mechanisms: one, the addition of new   standard objects through the definitions of new versions of the MIB;   two, the addition of widely-available but non-standard objects   through the experimental subtree; and three, the addition of private   objects through the enterprises subtree.  Such additional objects can   not only be used for vendor-specific elements, but also for   experimentation as required to further the knowledge of which other   objects are essential.   As more objects are defined using the second method, experience has   shown that the resulting MIB descriptions contain redundant   information.  In order to provide for MIB descriptions which are more   concise, and yet as informative, an enhancement is suggested.  This   enhancement allows the author of a MIB to remove the redundant   information, while retaining the important descriptive text.   Before presenting the approach, a brief presentation of columnar   object handling by the SNMP is necessary.  This explains and further   motivates the value of the enhancement.3.  Columnar Objects   The SNMP supports operations on MIB objects whose syntax is   ObjectSyntax as defined in the SMI.  Informally stated, SNMP   operations apply exclusively to scalar objects.  However, it is   convenient for developers of management applications to impose   imaginary, tabular structures on the ordered collection of objects   that constitute the MIB.  Each such conceptual table contains zero or   more rows, and each row may contain one or more scalar objects,   termed columnar objects.  Historically, this conceptualization has   been formalized by using the OBJECT-TYPE macro to define both an   object which corresponds to a table and an object which corresponds   to a row in that table.  (The ACCESS clause for such objects is   "not-accessible", of course.) However, it must be emphasized that, at   the protocol level, relationships among columnar objects in the same   row is a matter of convention, not of protocol.   Note that there are good reasons why the tabular structure is not a   matter of protocol.  Consider the operation of the SNMP Get-Next-PDU   acting on the last columnar object of an instance of a conceptualSNMP Working Group                                              [Page 3]

RFC 1212                Concise MIB Definitions               March 1991   row; it returns the next column of the first conceptual row or the   first object instance occurring after the table.  In contrast, if the   rows were a matter of protocol, then it would instead return an   error.  By not returning an error, a single PDU exchange informs the   manager that not only has the end of the conceptual row/table been   reached, but also provides information on the next object instance,   thereby increasing the information density of the PDU exchange.3.1.  Row Deletion   Nonetheless, it is highly useful to provide a means whereby a   conceptual row may be removed from a table. In MIB-II, this was   achieved by defining, for each conceptual row, an integer-valued   columnar object.  If a management station sets the value of this   object to some value, usually termed "invalid", then the effect is   one of invalidating the corresponding row in the table.  However, it   is an implementation-specific matter as to whether an agent removes   an invalidated entry from the table.  Accordingly, management   stations must be prepared to receive tabular information from agents   that corresponds to entries not currently in use.  Proper   interpretation of such entries requires examination of the columnar   object indicating the in-use status.3.2.  Row Addition   It is also highly useful to have a clear understanding of how a   conceptual row may be added to a table.  In the SNMP, at the protocol   level, a management station issues an SNMP set operation containing   an arbitrary set of variable bindings.  In the case that an agent   detects that one or more of those variable bindings refers to an   object instance not currently available in that agent, it may,   according to the rules of the SNMP, behave according to any of the   following paradigms:          (1)  It may reject the SNMP set operation as referring to               non-existent object instances by returning a response               with the error-status field set to "noSuchName" and the               error-index field set to refer to the first vacuous               reference.          (2)  It may accept the SNMP set operation as requesting the               creation  of new object instances corresponding to each               of the object instances named in the variable bindings.               The value of each (potentially) newly created object               instance is specified by the "value" component of the               relevant variable binding.  In this case, if the request               specifies a value for a newly (or previously) created               object that it deems inappropriate by reason of value orSNMP Working Group                                              [Page 4]

RFC 1212                Concise MIB Definitions               March 1991               syntax, then it rejects the SNMP set operation by               responding with the error-status field set to badValue               and the error-index field set to refer to the first               offending variable binding.          (3)  It may accept the SNMP set operation and create new               object instances as described in (2) above and, in               addition, at its discretion, create supplemental object               instances to complete a row in a conceptual table of               which the new object instances specified in the request               may be a part.   It should be emphasized that all three of the above behaviors are   fully conformant to the SNMP specification and are fully acceptable,   subject to any restrictions which may be imposed by access control   and/or the definitions of the MIB objects themselves.4.  Defining Objects   The Internet-standard SMI employs a two-level approach towards object   definition.  A MIB definition consists of two parts: a textual part,   in which objects are placed into groups, and a MIB module, in which   objects are described solely in terms of the ASN.1 macro OBJECT-TYPE,   which is defined by the SMI.   An example of the former definition might be:          OBJECT:          -------               sysLocation { system 6 }          Syntax:               DisplayString (SIZE (0..255))          Definition:               The physical location of this node (e.g., "telephone               closet, 3rd floor").          Access:               read-only.          Status:               mandatory.          An example of the latter definition might be:               sysLocation OBJECT-TYPE                   SYNTAX  DisplayString (SIZE (0..255))SNMP Working Group                                              [Page 5]

RFC 1212                Concise MIB Definitions               March 1991                   ACCESS  read-only                   STATUS  mandatory                   ::= { system 6 }          In the interests of brevity and to reduce the chance of          editing errors, it would seem useful to combine the two          definitions.  This can be accomplished by defining an          extension to the OBJECT-TYPE macro:          IMPORTS              ObjectName                  FROMRFC1155-SMI              DisplayString                  FROMRFC1158-MIB;          OBJECT-TYPE MACRO ::=          BEGIN              TYPE NOTATION ::=                                          -- must conform to                                          --RFC1155's ObjectSyntax                                "SYNTAX" type(ObjectSyntax)                                "ACCESS" Access                                "STATUS" Status                                DescrPart                                ReferPart                                IndexPart                                DefValPart              VALUE NOTATION ::= value (VALUE ObjectName)              Access ::= "read-only"                              | "read-write"                              | "write-only"                              | "not-accessible"              Status ::= "mandatory"                              | "optional"                              | "obsolete"                              | "deprecated"              DescrPart ::=                         "DESCRIPTION" value (description DisplayString)                              | empty              ReferPart ::=                         "REFERENCE" value (reference DisplayString)                              | empty              IndexPart ::=                         "INDEX" "{" IndexTypes "}"SNMP Working Group                                              [Page 6]

RFC 1212                Concise MIB Definitions               March 1991                              | empty              IndexTypes ::=                         IndexType | IndexTypes "," IndexType              IndexType ::=                                  -- if indexobject, use the SYNTAX                                  -- value of the correspondent                                  -- OBJECT-TYPE invocation                         value (indexobject ObjectName)                                  -- otherwise use named SMI type                                  -- must conform to IndexSyntax below                              | type (indextype)              DefValPart ::=                         "DEFVAL" "{" value (defvalue ObjectSyntax) "}"                              | empty          END          IndexSyntax ::=              CHOICE {                  number                      INTEGER (0..MAX),                  string                      OCTET STRING,                  object                      OBJECT IDENTIFIER,                  address                      NetworkAddress,                  ipAddress                      IpAddress              }4.1.  Mapping of the OBJECT-TYPE macro   It should be noted that the expansion of the OBJECT-TYPE macro is   something which conceptually happens during implementation and not   during run-time.4.1.1.  Mapping of the SYNTAX clause   The SYNTAX clause, which must be present, defines the abstract data   structure corresponding to that object type.  The ASN.1 language [6]   is used for this purpose.  However, the SMI purposely restricts the   ASN.1 constructs which may be used.  These restrictions are made   expressly for simplicity.SNMP Working Group                                              [Page 7]

RFC 1212                Concise MIB Definitions               March 19914.1.2.  Mapping of the ACCESS clause   The ACCESS clause, which must be present, defines the minimum level   of support required for that object type.  As a local matter,   implementations may support other access types (e.g., an   implementation may elect to permitting writing a variable marked as   read-only).  Further, protocol-specific "views" (e.g., those   indirectly implied by an SNMP community) may make further   restrictions on access to a variable.4.1.3.  Mapping of the STATUS clause   The STATUS clause, which must be present, defines the implementation   support required for that object type.4.1.4.  Mapping of the DESCRIPTION clause   The DESCRIPTION clause, which need not be present, contains a textual   definition of that object type which provides all semantic   definitions necessary for implementation, and should embody any   information which would otherwise be communicated in any ASN.1   commentary annotations associated with the object.  Note that, in   order to conform to the ASN.1 syntax, the entire value of this clause   must be enclosed in double quotation marks, although the value may be   multi-line.   Further, note that if the MIB module does not contain a textual   description of the object type elsewhere then the DESCRIPTION clause   must be present.4.1.5.  Mapping of the REFERENCE clause   The REFERENCE clause, which need not be present, contains a textual   cross-reference to an object defined in some other MIB module.  This   is useful when de-osifying a MIB produced by some other organization.4.1.6.  Mapping of the INDEX clause   The INDEX clause, which may be present only if that object type   corresponds to a conceptual row, defines instance identification   information for that object type.  (Historically, each MIB definition   contained a section entitled "Identification of OBJECT instances for   use with the SNMP".  By using the INDEX clause, this section need no   longer occur as this clause concisely captures the precise semantics   needed for instance identification.)   If the INDEX clause is not present, and the object type corresponds   to a non-columnar object, then instances of the object are identifiedSNMP Working Group                                              [Page 8]

RFC 1212                Concise MIB Definitions               March 1991   by appending a sub-identifier of zero to the name of that object.   Further, note that if the MIB module does not contain a textual   description of how instance identification information is derived for   columnar objects, then the INDEX clause must be present.   To define the instance identification information, determine which   object value(s) will unambiguously distinguish a conceptual row.  The   syntax of those objects indicate how to form the instance-identifier:          (1)  integer-valued: a single sub-identifier taking the               integer value (this works only for non-negative               integers);          (2)  string-valued, fixed-length strings: `n' sub-identifiers,               where `n' is the length of the string (each octet of the               string is encoded in a separate sub-identifier);          (3)  string-valued, variable-length strings: `n+1' sub-               identifiers, where `n' is the length of the string (the               first sub-identifier is `n' itself, following this, each               octet of the string is encoded in a separate sub-               identifier);          (4)  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);          (5)  NetworkAddress-valued: `n+1' sub-identifiers, where `n'               depends on the kind of address being encoded (the first               sub-identifier indicates the kind of address, value 1               indicates an IpAddress); or,          (6)  IpAddress-valued: 4 sub-identifiers, in the familiar               a.b.c.d notation.   Note that if an "indextype" value is present (e.g., INTEGER rather   than ifIndex), then a DESCRIPTION clause must be present; the text   contained therein indicates the semantics of the "indextype" value.SNMP Working Group                                              [Page 9]

RFC 1212                Concise MIB Definitions               March 1991   By way of example, in the context of MIB-II [7], the following INDEX   clauses might be present:                 objects under         INDEX clause               -----------------       ------------               ifEntry                 { ifIndex }               atEntry                 { atNetIfIndex,                                         atNetAddress }               ipAddrEntry             { ipAdEntAddr }               ipRouteEntry            { ipRouteDest }               ipNetToMediaEntry       { ipNetToMediaIfIndex,                                         ipNetToMediaNetAddress }               tcpConnEntry            { tcpConnLocalAddress,                                         tcpConnLocalPort,                                         tcpConnRemoteAddress,                                         tcpConnRemotePort }               udpEntry                { udpLocalAddress,                                         udpLocalPort }               egpNeighEntry           { egpNeighAddr }4.1.7.  Mapping of the DEFVAL clause   The DEFVAL clause, which need not be present, defines an acceptable   default value which may be used when an object instance is created at   the discretion of the agent acting in conformance with the third   paradigm described inSection 4.2 above.   During conceptual row creation, if an instance of a columnar object   is not present as one of the operands in the correspondent SNMP set   operation, then the value of the DEFVAL clause, if present, indicates   an acceptable default value that the agent might use.   The value of the DEFVAL clause must, of course, correspond to the   SYNTAX clause for the object.  Note that if an operand to the SNMP   set operation is an instance of a read-only object, then the error   noSuchName will be returned.  As such, the DEFVAL clause can be used   to provide an acceptable default value that the agent might use.   It is possible that no acceptable default value may exist for any of   the columnar objects in a conceptual row for which the creation of   new object instances is allowed.  In this case, the objects specified   in the INDEX clause must have a corresponding ACCESS clause value of   read-write.SNMP Working Group                                             [Page 10]

RFC 1212                Concise MIB Definitions               March 1991   By way of example, consider the following possible DEFVAL clauses:       ObjectSyntax            DEFVAL clause       -----------------       ------------       INTEGER                 1 -- same for Counter, Gauge, TimeTicks       OCTET STRING            'ffffffffffff'h       DisplayString           "any NVT ASCII string"       OBJECT IDENTIFIER       sysDescr       OBJECT IDENTIFIER       { system 2 }       NULL                    NULL       NetworkAddress          { internet 'c0210415'h }       IpAddress               'c0210415'h -- 192.33.4.214.1.8.  Mapping of the OBJECT-TYPE value   The value of an invocation of the OBJECT-TYPE macro is the name of   the object, which is an object identifier.4.2.  Usage Example   Consider how the ipNetToMediaTable from MIB-II might be fully   described:          -- the IP Address Translation tables          -- The Address Translation tables contain IpAddress to          -- "physical" address equivalences.  Some interfaces do not          -- use translation tables for determining address equivalences          -- (e.g., DDN-X.25 has an algorithmic method); if all          -- interfaces are of this type, then the Address Translation          -- table is empty, i.e., has zero entries.          ipNetToMediaTable OBJECT-TYPE              SYNTAX  SEQUENCE OF IpNetToMediaEntry              ACCESS  not-accessible              STATUS  mandatory              DESCRIPTION                      "The IP Address Translation table used for mapping                      from IP addresses to physical addresses."              ::= { ip 22 }          ipNetToMediaEntry OBJECT-TYPE              SYNTAX  IpNetToMediaEntry              ACCESS  not-accessible              STATUS  mandatory              DESCRIPTION                      "Each entry contains one IpAddress to 'physical'SNMP Working Group                                             [Page 11]

RFC 1212                Concise MIB Definitions               March 1991                      address equivalence."              INDEX   { ipNetToMediaIfIndex,                        ipNetToMediaNetAddress }              ::= { ipNetToMediaTable 1 }          IpNetToMediaEntry ::=              SEQUENCE {                  ipNetToMediaIfIndex                      INTEGER,                  ipNetToMediaPhysAddress                      OCTET STRING,                  ipNetToMediaNetAddress                      IpAddress,                  ipNetoToMediaType                      INTEGER              }          ipNetToMediaIfIndex OBJECT-TYPE              SYNTAX  INTEGER              ACCESS  read-write              STATUS  mandatory              DESCRIPTION                      "The interface on which this entry's equivalence                      is effective.  The interface identified by a                      particular value of this index is the same                      interface as identified by the same value of                      ifIndex."              ::= { ipNetToMediaEntry 1 }          ipNetToMediaPhysAddress OBJECT-TYPE              SYNTAX  OCTET STRING              ACCESS  read-write              STATUS  mandatory              DESCRIPTION                      "The media-dependent 'physical' address."              ::= { ipNetToMediaEntry 2 }          ipNetToMediaNetAddress OBJECT-TYPE              SYNTAX  IpAddress              ACCESS  read-write              STATUS  mandatory              DESCRIPTION                      "The IpAddress corresponding to the media-                      dependent 'physical' address."              ::= { ipNetToMediaEntry 3 }          ipNetToMediaType OBJECT-TYPE              SYNTAX  INTEGER {SNMP Working Group                                             [Page 12]

RFC 1212                Concise MIB Definitions               March 1991                          other(1),   -- none of the following                          invalid(2), -- an invalidated mapping                          dynamic(3),                          static(4)                      }              ACCESS  read-write              STATUS  mandatory              DESCRIPTION                      "The type of mapping.                      Setting this object to the value invalid(2) has                      the effect of invalidating the corresponding entry                      in the ipNetToMediaTable.  That is, it effectively                      disassociates the interface identified with said                      entry from the mapping identified with said entry.                      It is an implementation-specific matter as to                      whether the agent removes an invalidated entry                      from the table.  Accordingly, management stations                      must be prepared to receive tabular information                      from agents that corresponds to entries not                      currently in use.  Proper interpretation of such                      entries requires examination of the relevant                      ipNetToMediaType object."                  ::= { ipNetToMediaEntry 4 }5.  Appendix: DE-osifying MIBs   There has been an increasing amount of work recently on taking MIBs   defined by other organizations (e.g., the IEEE) and de-osifying them   for use with the Internet-standard network management framework.  The   steps to achieve this are straight-forward, though tedious.  Of   course, it is helpful to already be experienced in writing MIB   modules for use with the Internet-standard network management   framework.   The first step is to construct a skeletal MIB module, e.g.,RFC1213-MIB DEFINITIONS ::= BEGIN               IMPORTS                       experimental, OBJECT-TYPE, Counter                           FROMRFC1155-SMI;                       -- contact IANA for actual number               root    OBJECT IDENTIFIER ::= { experimental xx }               ENDSNMP Working Group                                             [Page 13]

RFC 1212                Concise MIB Definitions               March 1991   The next step is to categorize the objects into groups.  For   experimental MIBs, optional objects are permitted.  However, when a   MIB module is placed in the Internet-standard space, these optional   objects are either removed, or placed in a optional group, which, if   implemented, all objects in the group must be implemented.  For the   first pass, it is wisest to simply ignore any optional objects in the   original MIB: experience shows it is better to define a core MIB   module first, containing only essential objects; later, if experience   demands, other objects can be added.   It must be emphasized that groups are "units of conformance" within a   MIB: everything in a group is "mandatory" and implementations do   either whole groups or none.5.1.  Managed Object Mapping   Next for each managed object class, determine whether there can exist   multiple instances of that managed object class.  If not, then for   each of its attributes, use the OBJECT-TYPE macro to make an   equivalent definition.   Otherwise, if multiple instances of the managed object class can   exist, then define a conceptual table having conceptual rows each   containing a columnar object for each of the managed object class's   attributes. If the managed object class is contained within the   containment tree of another managed object class, then the assignment   of an object type is normally required for each of the "distinguished   attributes" of the containing managed object class.  If they do not   already exist within the MIB module, then they can be added via the   definition of additional columnar objects in the conceptual row   corresponding to the contained managed object class.   In defining a conceptual row, it is useful to consider the   optimization of network management operations which will act upon its   columnar objects.  In particular, it is wisest to avoid defining more   columnar objects within a conceptual row, than can fit in a single   PDU.  As a rule of thumb, a conceptual row should contain no more   than approximately 20 objects.  Similarly, or as a way to abide by   the "20 object guideline", columnar objects should be grouped into   tables according to the expected grouping of network management   operations upon them.  As such, the content of conceptual rows should   reflect typical access scenarios, e.g., they should be organized   along functional lines such as one row for statistics and another row   for parameters, or along usage lines such as commonly-needed objects   versus rarely-needed objects.   On the other hand, the definition of conceptual rows where the number   of columnar objects used as indexes outnumbers the number used toSNMP Working Group                                             [Page 14]

RFC 1212                Concise MIB Definitions               March 1991   hold information, should also be avoided.  In particular, the   splitting of a managed object class's attributes into many conceptual   tables should not be used as a way to obtain the same degree of   flexibility/complexity as is often found in MIB's with a myriad of   optionals.5.1.1.  Mapping to the SYNTAX clause   When mapping to the SYNTAX clause of the OBJECT-type macro:          (1)  An object with BOOLEAN syntax becomes an INTEGER taking               either of values true(1) or false(2).          (2)  An object with ENUMERATED syntax becomes an INTEGER,               taking any of the values given.          (3)  An object with BIT STRING syntax containing no more than               32 bits becomes an INTEGER defined as a sum; otherwise if               more than 32 bits are present, the object becomes an               OCTET STRING, with the bits numbered from left-to-right,               in which the least significant bits of the last octet may               be "reserved for future use".          (4)  An object with a character string syntax becomes either               an OCTET STRING or a DisplayString, depending on the               repertoire of the character string.          (5)  An non-tabular object with a complex syntax, such as REAL               or EXTERNAL, must be decomposed, usually into an OCTET               STRING (if sensible).  As a rule, any object with a               complicated syntax should be avoided.          (6)  Tabular objects must be decomposed into rows of columnar               objects.5.1.2.  Mapping to the ACCESS clause   This is straight-forward.5.1.3.  Mapping to the STATUS clause   This is usually straight-forward; however, some osified-MIBs use the   term "recommended".  In this case, a choice must be made between   "mandatory" and "optional".5.1.4.  Mapping to the DESCRIPTION clause   This is straight-forward: simply copy the text, making sure that anySNMP Working Group                                             [Page 15]

RFC 1212                Concise MIB Definitions               March 1991   embedded double quotation marks are sanitized (i.e., replaced with   single-quotes or removed).5.1.5.  Mapping to the REFERENCE clause   This is straight-forward: simply include a textual reference to the   object being mapped, the document which defines the object, and   perhaps a page number in the document.5.1.6.  Mapping to the INDEX clause   Decide how instance-identifiers for columnar objects are to be formed   and define this clause accordingly.5.1.7.  Mapping to the DEFVAL clause   Decide if a meaningful default value can be assigned to the object   being mapped, and if so, define the DEFVAL clause accordingly.5.2.  Action Mapping   Actions are modeled as read-write objects, in which writing a   particular value results in the action taking place.5.2.1.  Mapping to the SYNTAX clause   Usually an INTEGER syntax is used with a distinguished value provided   for each action that the object provides access to.  In addition,   there is usually one other distinguished value, which is the one   returned when the object is read.5.2.2.  Mapping to the ACCESS clause   Always use read-write.5.2.3.  Mapping to the STATUS clause   This is straight-forward.5.2.4.  Mapping to the DESCRIPTION clause   This is straight-forward: simply copy the text, making sure that any   embedded double quotation marks are sanitized (i.e., replaced with   single-quotes or removed).5.2.5.  Mapping to the REFERENCE clause   This is straight-forward: simply include a textual reference to theSNMP Working Group                                             [Page 16]

RFC 1212                Concise MIB Definitions               March 1991   action being mapped, the document which defines the action, and   perhaps a page number in the document.6.  Acknowledgements   This document was produced by the SNMP Working Group:               Anne Ambler, Spider               Karl Auerbach, Sun               Fred Baker, ACC               Ken Brinkerhoff               Ron Broersma, NOSC               Jack Brown, US Army               Theodore Brunner, Bellcore               Jeffrey Buffum, HP               John Burress, Wellfleet               Jeffrey D. Case, University of Tennessee at Knoxville               Chris Chiptasso, Spartacus               Paul Ciarfella, DEC               Bob Collet               John Cook, Chipcom               Tracy Cox, Bellcore               James R. Davin, MIT-LCS               Eric Decker, cisco               Kurt Dobbins, Cabletron               Nadya El-Afandi, Network Systems               Gary Ellis, HP               Fred Engle               Mike Erlinger               Mark S. Fedor, PSI               Richard Fox, Synoptics               Karen Frisa, CMU               Chris Gunner, DEC               Fred Harris, University of Tennessee at Knoxville               Ken Hibbard, Xylogics               Ole Jacobsen, Interop               Ken Jones               Satish Joshi, Synoptics               Frank Kastenholz, Racal-Interlan               Shimshon Kaufman, Spartacus               Ken Key, University of Tennessee at Knoxville               Jim Kinder, Fibercom               Alex Koifman, BBN               Christopher Kolb, PSI               Cheryl Krupczak, NCR               Paul Langille, DEC               Peter Lin, Vitalink               John Lunny, TWGSNMP Working Group                                             [Page 17]

RFC 1212                Concise MIB Definitions               March 1991               Carl Malamud               Randy Mayhew, University of Tennessee at Knoxville               Keith McCloghrie, Hughes LAN Systems               Donna McMaster, David Systems               Lynn Monsanto, Sun               Dave Perkins, 3COM               Jim Reinstedler, Ungerman Bass               Anil Rijsinghani, DEC               Kathy Rinehart, Arnold AFB               Kary Robertson               Marshall T. Rose, PSI (chair)               L. Michael Sabo, NCSC               Jon Saperia, DEC               Greg Satz, cisco               Martin Schoffstall, PSI               John Seligson               Steve Sherry, Xyplex               Fei Shu, NEC               Sam Sjogren, TGV               Mark Sleeper, Sparta               Lance Sprung               Mike St.Johns               Bob Stewart, Xyplex               Emil Sturniold               Kaj Tesink, Bellcore               Dean Throop, Data General               Bill Townsend, Xylogics               Maurice Turcotte, Racal-Milgo               Kannan Varadhou               Sudhanshu Verma, HP               Bill Versteeg, Network Research Corporation               Warren Vik, Interactive Systems               David Waitzman, BBN               Steve Waldbusser, CMU               Dan Wintringhan               David Wood               Wengyik Yeong, PSI               Jeff Young, Cray Research7.  References   [1] Cerf, V., "IAB Recommendations for the Development of Internet       Network Management Standards",RFC 1052, NRI, April 1988.   [2] Cerf, V., "Report of the Second Ad Hoc Network Management Review       Group",RFC 1109, NRI, August 1989.   [3] Rose M., and K. McCloghrie, "Structure and Identification ofSNMP Working Group                                             [Page 18]

RFC 1212                Concise MIB Definitions               March 1991       Management Information for TCP/IP-based internets",RFC 1155,       Performance Systems International, Hughes LAN Systems, May 1990.   [4] McCloghrie K., and M. Rose, "Management Information Base for       Network Management of TCP/IP-based internets",RFC 1156, Hughes       LAN Systems, Performance Systems International, May 1990.   [5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple       Network Management Protocol",RFC 1157, SNMP Research,       Performance Systems International, Performance Systems       International, MIT Laboratory for Computer Science, May 1990.   [6] Information processing systems - Open Systems Interconnection -       Specification of Abstract Syntax Notation One (ASN.1),       International Organization for Standardization International       Standard 8824, December 1987.   [7] Rose M., Editor, "Management Information Base for Network       Management of TCP/IP-based internets: MIB-II",RFC 1213,       Performance Systems International, March 1991.8.  Security Considerations   Security issues are not discussed in this memo.9.  Authors' Addresses   Marshall T. Rose   Performance Systems International   5201 Great America Parkway   Suite 3106   Santa Clara, CA  95054   Phone: +1 408 562 6222   EMail: mrose@psi.com   X.500:  rose, psi, us   Keith McCloghrie   Hughes LAN Systems   1225 Charleston Road   Mountain View, CA 94043   1225 Charleston Road   Mountain View, CA 94043   Phone: (415) 966-7934   EMail: kzm@hls.comSNMP Working Group                                             [Page 19]

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