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rfc:rfc1155

Network Working Group M. Rose Request for Comments: 1155 Performance Systems International Obsoletes: RFC 1065 K. McCloghrie

                                                    Hughes LAN Systems
                                                              May 1990
       Structure and Identification of Management Information
                     for TCP/IP-based Internets
                         Table of Contents

1. Status of this Memo ……………………………………… 1 2. Introduction ……………………………………………. 2 3. Structure and Identification of Management Information……….. 4 3.1 Names …………………………………………………. 4 3.1.1 Directory ……………………………………………. 5 3.1.2 Mgmt ………………………………………………… 6 3.1.3 Experimental …………………………………………. 6 3.1.4 Private ……………………………………………… 7 3.2 Syntax ………………………………………………… 7 3.2.1 Primitive Types ………………………………………. 7 3.2.1.1 Guidelines for Enumerated INTEGERs ……………………. 7 3.2.2 Constructor Types …………………………………….. 8 3.2.3 Defined Types ………………………………………… 8 3.2.3.1 NetworkAddress ……………………………………… 8 3.2.3.2 IpAddress ………………………………………….. 8 3.2.3.3 Counter ……………………………………………. 8 3.2.3.4 Gauge ……………………………………………… 9 3.2.3.5 TimeTicks ………………………………………….. 9 3.2.3.6 Opaque …………………………………………….. 9 3.3 Encodings ……………………………………………… 9 4. Managed Objects …………………………………………. 10 4.1 Guidelines for Object Names ……………………………… 10 4.2 Object Types and Instances ………………………………. 10 4.3 Macros for Managed Objects ………………………………. 14 5. Extensions to the MIB ……………………………………. 16 6. Definitions …………………………………………….. 17 7. Acknowledgements ………………………………………… 20 8. References ……………………………………………… 21 9. Security Considerations…………………………………… 21 10. Authors' Addresses………………………………………. 22

1. Status of this Memo

 This RFC is a re-release of RFC 1065, with a changed "Status of this
 Memo", plus a few minor typographical corrections.  The technical

Rose & McCloghrie [Page 1] RFC 1155 SMI May 1990

 content of the document is unchanged from RFC 1065.
 This memo provides the common definitions for the structure and
 identification of management information for TCP/IP-based internets.
 In particular, together with its companion memos which describe the
 management information base along with the network management
 protocol, these documents provide a simple, workable architecture and
 system for managing TCP/IP-based internets and in particular, the
 Internet.
 This memo specifies a Standard Protocol for the Internet community.
 Its status is "Recommended".  TCP/IP implementations in the Internet
 which are network manageable are expected to adopt and implement this
 specification.
 The Internet Activities Board recommends that all IP and TCP
 implementations be network manageable.  This implies implementation
 of the Internet MIB (RFC-1156) and at least one of the two
 recommended management protocols SNMP (RFC-1157) or CMOT (RFC-1095).
 It should be noted that, at this time, SNMP is a full Internet
 standard and CMOT is a draft standard.  See also the Host and Gateway
 Requirements RFCs for more specific information on the applicability
 of this standard.
 Please refer to the latest edition of the "IAB Official Protocol
 Standards" RFC for current information on the state and status of
 standard Internet protocols.
 Distribution of this memo is unlimited.

2. Introduction

 This memo describes the common structures and identification scheme
 for the definition of management information used in managing
 TCP/IP-based internets.  Included are descriptions of an object
 information model for network management along with a set of generic
 types used to describe management information.  Formal descriptions
 of the structure are given using Abstract Syntax Notation One (ASN.1)
 [1].
 This memo is largely concerned with organizational concerns and
 administrative policy:  it neither specifies the objects which are
 managed, nor the protocols used to manage those objects.  These
 concerns are addressed by two companion memos:  one describing the
 Management Information Base (MIB) [2], and the other describing the
 Simple Network Management Protocol (SNMP) [3].
 This memo is based in part on the work of the Internet Engineering

Rose & McCloghrie [Page 2] RFC 1155 SMI May 1990

 Task Force, particularly the working note titled "Structure and
 Identification of Management Information for the Internet" [4].  This
 memo uses a skeletal structure derived from that note, but differs in
 one very significant way:  that note focuses entirely on the use of
 OSI-style network management.  As such, it is not suitable for use
 with SNMP.
 This memo attempts to achieve two goals:  simplicity and
 extensibility.  Both are motivated by a common concern:  although the
 management of TCP/IP-based internets has been a topic of study for
 some time, the authors do not feel that the depth and breadth of such
 understanding is complete.  More bluntly, we feel that previous
 experiences, while giving the community insight, are hardly
 conclusive.  By fostering a simple SMI, the minimal number of
 constraints are imposed on future potential approaches; further, by
 fostering an extensible SMI, the maximal number of potential
 approaches are available for experimentation.
 It is believed that this memo and its two companions comply with the
 guidelines set forth in RFC 1052, "IAB Recommendations for the
 Development of Internet Network Management Standards" [5] and RFC
 1109, "Report of the Second Ad Hoc Network Management Review Group"
 [6].  In particular, we feel that this memo, along with the memo
 describing the management information base, provide a solid basis for
 network management of the Internet.

Rose & McCloghrie [Page 3] RFC 1155 SMI May 1990

3. Structure and Identification of Management Information

 Managed objects are accessed via a virtual information store, termed
 the Management Information Base or MIB.  Objects in the MIB are
 defined using Abstract Syntax Notation One (ASN.1) [1].
 Each type of object (termed an object type) has a name, a syntax, and
 an encoding.  The name is represented uniquely as an OBJECT
 IDENTIFIER.  An OBJECT IDENTIFIER is an administratively assigned
 name.  The administrative policies used for assigning names are
 discussed later in this memo.
 The syntax for an object type defines the abstract data structure
 corresponding to that object type.  For example, the structure of a
 given object type might be an INTEGER or OCTET STRING.  Although in
 general, we should permit any ASN.1 construct to be available for use
 in defining the syntax of an object type, this memo purposely
 restricts the ASN.1 constructs which may be used.  These restrictions
 are made solely for the sake of simplicity.
 The encoding of an object type is simply how instances of that object
 type are represented using the object's type syntax.  Implicitly tied
 to the notion of an object's syntax and encoding is how the object is
 represented when being transmitted on the network.  This memo
 specifies the use of the basic encoding rules of ASN.1 [7].
 It is beyond the scope of this memo to define either the MIB used for
 network management or the network management protocol.  As mentioned
 earlier, these tasks are left to companion memos.  This memo attempts
 to minimize the restrictions placed upon its companions so as to
 maximize generality.  However, in some cases, restrictions have been
 made (e.g., the syntax which may be used when defining object types
 in the MIB) in order to encourage a particular style of management.
 Future editions of this memo may remove these restrictions.

3.1. Names

 Names are used to identify managed objects.  This memo specifies
 names which are hierarchical in nature.  The OBJECT IDENTIFIER
 concept is used to model this notion.  An OBJECT IDENTIFIER can be
 used for purposes other than naming managed object types; for
 example, each international standard has an OBJECT IDENTIFIER
 assigned to it for the purposes of identification.  In short, OBJECT
 IDENTIFIERs are a means for identifying some object, regardless of
 the semantics associated with the object (e.g., a network object, a
 standards document, etc.)
 An OBJECT IDENTIFIER is a sequence of integers which traverse a

Rose & McCloghrie [Page 4] RFC 1155 SMI May 1990

 global tree.  The tree consists of a root connected to a number of
 labeled nodes via edges.  Each node may, in turn, have children of
 its own which are labeled.  In this case, we may term the node a
 subtree.  This process may continue to an arbitrary level of depth.
 Central to the notion of the OBJECT IDENTIFIER is the understanding
 that administrative control of the meanings assigned to the nodes may
 be delegated as one traverses the tree.  A label is a pairing of a
 brief textual description and an integer.
 The root node itself is unlabeled, but has at least three children
 directly under it:  one node is administered by the International
 Organization for Standardization, with label iso(1); another is
 administrated by the International Telegraph and Telephone
 Consultative Committee, with label ccitt(0); and the third is jointly
 administered by the ISO and the CCITT, joint-iso-ccitt(2).
 Under the iso(1) node, the ISO has designated one subtree for use by
 other (inter)national organizations, org(3).  Of the children nodes
 present, two have been assigned to the U.S. National Institutes of
 Standards and Technology.  One of these subtrees has been transferred
 by the NIST to the U.S. Department of Defense, dod(6).
 As of this writing, the DoD has not indicated how it will manage its
 subtree of OBJECT IDENTIFIERs.  This memo assumes that DoD will
 allocate a node to the Internet community, to be administered by the
 Internet Activities Board (IAB) as follows:
    internet    OBJECT IDENTIFIER ::= { iso org(3) dod(6) 1 }
 That is, the Internet subtree of OBJECT IDENTIFIERs starts with the
 prefix:
    1.3.6.1.
 This memo, as a standard approved by the IAB, now specifies the
 policy under which this subtree of OBJECT IDENTIFIERs is
 administered.  Initially, four nodes are present:
    directory     OBJECT IDENTIFIER ::= { internet 1 }
    mgmt          OBJECT IDENTIFIER ::= { internet 2 }
    experimental  OBJECT IDENTIFIER ::= { internet 3 }
    private       OBJECT IDENTIFIER ::= { internet 4 }

3.1.1. Directory

 The directory(1) subtree is reserved for use with a future memo that
 discusses how the OSI Directory may be used in the Internet.

Rose & McCloghrie [Page 5] RFC 1155 SMI May 1990

3.1.2. Mgmt

 The mgmt(2) subtree is used to identify objects which are defined in
 IAB-approved documents.  Administration of the mgmt(2) subtree is
 delegated by the IAB to the Internet Assigned Numbers Authority for
 the Internet.  As RFCs which define new versions of the Internet-
 standard Management Information Base are approved, they are assigned
 an OBJECT IDENTIFIER by the Internet Assigned Numbers Authority for
 identifying the objects defined by that memo.
 For example, the RFC which defines the initial Internet standard MIB
 would be assigned management document number 1.  This RFC would use
 the OBJECT IDENTIFIER
    { mgmt 1 }
 or
    1.3.6.1.2.1
 in defining the Internet-standard MIB.
 The generation of new versions of the Internet-standard MIB is a
 rigorous process.  Section 5 of this memo describes the rules used
 when a new version is defined.

3.1.3. Experimental

 The experimental(3) subtree is used to identify objects used in
 Internet experiments.  Administration of the experimental(3) subtree
 is delegated by the IAB to the Internet Assigned Numbers Authority of
 the Internet.
 For example, an experimenter might received number 17, and would have
 available the OBJECT IDENTIFIER
    { experimental 17 }
 or
    1.3.6.1.3.17
 for use.
 As a part of the assignment process, the Internet Assigned Numbers
 Authority may make requirements as to how that subtree is used.

Rose & McCloghrie [Page 6] RFC 1155 SMI May 1990

3.1.4. Private

 The private(4) subtree is used to identify objects defined
 unilaterally.  Administration of the private(4) subtree is delegated
 by the IAB to the Internet Assigned Numbers Authority for the
 Internet.  Initially, this subtree has at least one child:
    enterprises   OBJECT IDENTIFIER ::= { private 1 }
 The enterprises(1) subtree is used, among other things, to permit
 parties providing networking subsystems to register models of their
 products.
 Upon receiving a subtree, the enterprise may, for example, define new
 MIB objects in this subtree.  In addition, it is strongly recommended
 that the enterprise will also register its networking subsystems
 under this subtree, in order to provide an unambiguous identification
 mechanism for use in management protocols.  For example, if the
 "Flintstones, Inc."  enterprise produced networking subsystems, then
 they could request a node under the enterprises subtree from the
 Internet Assigned Numbers Authority.  Such a node might be numbered:
    1.3.6.1.4.1.42
 The "Flintstones, Inc." enterprise might then register their "Fred
 Router" under the name of:
    1.3.6.1.4.1.42.1.1

3.2. Syntax

 Syntax is used to define the structure corresponding to object types.
 ASN.1 constructs are used to define this structure, although the full
 generality of ASN.1 is not permitted.
 The ASN.1 type ObjectSyntax defines the different syntaxes which may
 be used in defining an object type.

3.2.1. Primitive Types

 Only the ASN.1 primitive types INTEGER, OCTET STRING, OBJECT
 IDENTIFIER, and NULL are permitted.  These are sometimes referred to
 as non-aggregate types.

3.2.1.1. Guidelines for Enumerated INTEGERs

 If an enumerated INTEGER is listed as an object type, then a named-
 number having the value 0 shall not be present in the list of

Rose & McCloghrie [Page 7] RFC 1155 SMI May 1990

 enumerations.  Use of this value is prohibited.

3.2.2. Constructor Types

 The ASN.1 constructor type SEQUENCE is permitted, providing that it
 is used to generate either lists or tables.
 For lists, the syntax takes the form:
    SEQUENCE { <type1>, ..., <typeN> }
 where each <type> resolves to one of the ASN.1 primitive types listed
 above.  Further, these ASN.1 types are always present (the DEFAULT
 and OPTIONAL clauses do not appear in the SEQUENCE definition).
 For tables, the syntax takes the form:
    SEQUENCE OF <entry>
 where <entry> resolves to a list constructor.
 Lists and tables are sometimes referred to as aggregate types.

3.2.3. Defined Types

 In addition, new application-wide types may be defined, so long as
 they resolve into an IMPLICITly defined ASN.1 primitive type, list,
 table, or some other application-wide type.  Initially, few
 application-wide types are defined.  Future memos will no doubt
 define others once a consensus is reached.

3.2.3.1. NetworkAddress

 This CHOICE represents an address from one of possibly several
 protocol families.  Currently, only one protocol family, the Internet
 family, is present in this CHOICE.

3.2.3.2. IpAddress

 This application-wide type represents a 32-bit internet address.  It
 is represented as an OCTET STRING of length 4, in network byte-order.
 When this ASN.1 type is encoded using the ASN.1 basic encoding rules,
 only the primitive encoding form shall be used.

3.2.3.3. Counter

 This application-wide type represents a non-negative integer which

Rose & McCloghrie [Page 8] RFC 1155 SMI May 1990

 monotonically increases until it reaches a maximum value, when it
 wraps around and starts increasing again from zero.  This memo
 specifies a maximum value of 2^32-1 (4294967295 decimal) for
 counters.

3.2.3.4. Gauge

 This application-wide type represents a non-negative integer, which
 may increase or decrease, but which latches at a maximum value.  This
 memo specifies a maximum value of 2^32-1 (4294967295 decimal) for
 gauges.

3.2.3.5. TimeTicks

 This application-wide type represents a non-negative integer which
 counts the time in hundredths of a second since some epoch.  When
 object types are defined in the MIB which use this ASN.1 type, the
 description of the object type identifies the reference epoch.

3.2.3.6. Opaque

 This application-wide type supports the capability to pass arbitrary
 ASN.1 syntax.  A value is encoded using the ASN.1 basic rules into a
 string of octets.  This, in turn, is encoded as an OCTET STRING, in
 effect "double-wrapping" the original ASN.1 value.
 Note that a conforming implementation need only be able to accept and
 recognize opaquely-encoded data.  It need not be able to unwrap the
 data and then interpret its contents.
 Further note that by use of the ASN.1 EXTERNAL type, encodings other
 than ASN.1 may be used in opaquely-encoded data.

3.3. Encodings

 Once an instance of an object type has been identified, its value may
 be transmitted by applying the basic encoding rules of ASN.1 to the
 syntax for the object type.

Rose & McCloghrie [Page 9] RFC 1155 SMI May 1990

4. Managed Objects

 Although it is not the purpose of this memo to define objects in the
 MIB, this memo specifies a format to be used by other memos which
 define these objects.
 An object type definition consists of five fields:
 OBJECT:
 -------
    A textual name, termed the OBJECT DESCRIPTOR, for the object type,
    along with its corresponding OBJECT IDENTIFIER.
 Syntax:
    The abstract syntax for the object type.  This must resolve to an
    instance of the ASN.1 type ObjectSyntax (defined below).
 Definition:
    A textual description of the semantics of the object type.
    Implementations should ensure that their instance of the object
    fulfills this definition since this MIB is intended for use in
    multi-vendor environments.  As such it is vital that objects have
    consistent meaning across all machines.
 Access:
    One of read-only, read-write, write-only, or not-accessible.
 Status:
    One of mandatory, optional, or obsolete.
 Future memos may also specify other fields for the objects which they
 define.

4.1. Guidelines for Object Names

 No object type in the Internet-Standard MIB shall use a sub-
 identifier of 0 in its name.  This value is reserved for use with
 future extensions.
 Each OBJECT DESCRIPTOR corresponding to an object type in the
 internet-standard MIB shall be a unique, but mnemonic, printable
 string.  This promotes a common language for humans to use when
 discussing the MIB and also facilitates simple table mappings for
 user interfaces.

4.2. Object Types and Instances

 An object type is a definition of a kind of managed object; it is

Rose & McCloghrie [Page 10] RFC 1155 SMI May 1990

 declarative in nature.  In contrast, an object instance is an
 instantiation of an object type which has been bound to a value.  For
 example, the notion of an entry in a routing table might be defined
 in the MIB.  Such a notion corresponds to an object type; individual
 entries in a particular routing table which exist at some time are
 object instances of that object type.
 A collection of object types is defined in the MIB.  Each such
 subject type is uniquely named by its OBJECT IDENTIFIER and also has
 a textual name, which is its OBJECT DESCRIPTOR.  The means whereby
 object instances are referenced is not defined in the MIB.  Reference
 to object instances is achieved by a protocol-specific mechanism:  it
 is the responsibility of each management protocol adhering to the SMI
 to define this mechanism.
 An object type may be defined in the MIB such that an instance of
 that object type represents an aggregation of information also
 represented by instances of some number of "subordinate" object
 types.  For example, suppose the following object types are defined
 in the MIB:
 OBJECT:
 -------
    atIndex { atEntry 1 }
 Syntax:
    INTEGER
 Definition:
    The interface number for the physical address.
 Access:
    read-write.
 Status:
    mandatory.
 OBJECT:
 -------
    atPhysAddress { atEntry 2 }
 Syntax:
    OCTET STRING
 Definition:
    The media-dependent physical address.

Rose & McCloghrie [Page 11] RFC 1155 SMI May 1990

 Access:
    read-write.
 Status:
    mandatory.
 OBJECT:
 -------
    atNetAddress { atEntry 3 }
 Syntax:
    NetworkAddress
 Definition:
    The network address corresponding to the media-dependent physical
    address.
 Access:
    read-write.
 Status:
    mandatory.
 Then, a fourth object type might also be defined in the MIB:
 OBJECT:
 -------
    atEntry { atTable 1 }
 Syntax:
    AtEntry ::= SEQUENCE {
          atIndex
          INTEGER,
          atPhysAddress
          OCTET STRING,
          atNetAddress
          NetworkAddress
          }
 Definition:
    An entry in the address translation table.
 Access:
    read-write.

Rose & McCloghrie [Page 12] RFC 1155 SMI May 1990

 Status:
    mandatory.
 Each instance of this object type comprises information represented
 by instances of the former three object types.  An object type
 defined in this way is called a list.
 Similarly, tables can be formed by aggregations of a list type.  For
 example, a fifth object type might also be defined in the MIB:
 OBJECT:
 ------
    atTable { at 1 }
 Syntax:
    SEQUENCE OF AtEntry
 Definition:
    The address translation table.
 Access:
    read-write.
 Status:
    mandatory.
 such that each instance of the atTable object comprises information
 represented by the set of atEntry object types that collectively
 constitute a given atTable object instance, that is, a given address
 translation table.
 Consider how one might refer to a simple object within a table.
 Continuing with the previous example, one might name the object type
    { atPhysAddress }
 and specify, using a protocol-specific mechanism, the object instance
    { atNetAddress } = { internet "10.0.0.52" }
 This pairing of object type and object instance would refer to all
 instances of atPhysAddress which are part of any entry in some
 address translation table for which the associated atNetAddress value
 is { internet "10.0.0.52" }.
 To continue with this example, consider how one might refer to an
 aggregate object (list) within a table.  Naming the object type

Rose & McCloghrie [Page 13] RFC 1155 SMI May 1990

    { atEntry }
 and specifying, using a protocol-specific mechanism, the object
 instance
    { atNetAddress } = { internet "10.0.0.52" }
 refers to all instances of entries in the table for which the
 associated atNetAddress value is { internet "10.0.0.52" }.
 Each management protocol must provide a mechanism for accessing
 simple (non-aggregate) object types.  Each management protocol
 specifies whether or not it supports access to aggregate object
 types.  Further, the protocol must specify which instances are
 "returned" when an object type/instance pairing refers to more than
 one instance of a type.
 To afford support for a variety of management protocols, all
 information by which instances of a given object type may be usefully
 distinguished, one from another, is represented by instances of
 object types defined in the MIB.

4.3. Macros for Managed Objects

 In order to facilitate the use of tools for processing the definition
 of the MIB, the OBJECT-TYPE macro may be used.  This macro permits
 the key aspects of an object type to be represented in a formal way.
    OBJECT-TYPE MACRO ::=
    BEGIN
        TYPE NOTATION ::= "SYNTAX" type (TYPE ObjectSyntax)
                          "ACCESS" Access
                          "STATUS" Status
        VALUE NOTATION ::= value (VALUE ObjectName)
        Access ::= "read-only"
                        | "read-write"
                        | "write-only"
                        | "not-accessible"
        Status ::= "mandatory"
                        | "optional"
                        | "obsolete"
        END
 Given the object types defined earlier, we might imagine the
 following definitions being present in the MIB:
                atIndex OBJECT-TYPE

Rose & McCloghrie [Page 14] RFC 1155 SMI May 1990

                        SYNTAX  INTEGER
                        ACCESS  read-write
                        STATUS  mandatory
                        ::= { atEntry 1 }
                atPhysAddress OBJECT-TYPE
                        SYNTAX  OCTET STRING
                        ACCESS  read-write
                        STATUS  mandatory
                        ::= { atEntry 2 }
                atNetAddress OBJECT-TYPE
                        SYNTAX  NetworkAddress
                        ACCESS  read-write
                        STATUS  mandatory
                        ::= { atEntry 3 }
                atEntry OBJECT-TYPE
                        SYNTAX  AtEntry
                        ACCESS  read-write
                        STATUS  mandatory
                        ::= { atTable 1 }
                atTable OBJECT-TYPE
                        SYNTAX  SEQUENCE OF AtEntry
                        ACCESS  read-write
                        STATUS  mandatory
                        ::= { at 1 }
                AtEntry ::= SEQUENCE {
                    atIndex
                        INTEGER,
                    atPhysAddress
                        OCTET STRING,
                    atNetAddress
                        NetworkAddress
                }
 The first five definitions describe object types, relating, for
 example, the OBJECT DESCRIPTOR atIndex to the OBJECT IDENTIFIER {
 atEntry 1 }.  In addition, the syntax of this object is defined
 (INTEGER) along with the access permitted (read-write) and status
 (mandatory).  The sixth definition describes an ASN.1 type called
 AtEntry.

Rose & McCloghrie [Page 15] RFC 1155 SMI May 1990

5. Extensions to the MIB

 Every Internet-standard MIB document obsoletes all previous such
 documents.  The portion of a name, termed the tail, following the
 OBJECT IDENTIFIER
    { mgmt version-number }
 used to name objects shall remain unchanged between versions.  New
 versions may:
    (1) declare old object types obsolete (if necessary), but not
    delete their names;
    (2) augment the definition of an object type corresponding to a
    list by appending non-aggregate object types to the object types
    in the list; or,
    (3) define entirely new object types.
 New versions may not:
    (1) change the semantics of any previously defined object without
    changing the name of that object.
 These rules are important because they admit easier support for
 multiple versions of the Internet-standard MIB.  In particular, the
 semantics associated with the tail of a name remain constant
 throughout different versions of the MIB.  Because multiple versions
 of the MIB may thus coincide in "tail-space," implementations
 supporting multiple versions of the MIB can be vastly simplified.
 However, as a consequence, a management agent might return an
 instance corresponding to a superset of the expected object type.
 Following the principle of robustness, in this exceptional case, a
 manager should ignore any additional information beyond the
 definition of the expected object type.  However, the robustness
 principle requires that one exercise care with respect to control
 actions:  if an instance does not have the same syntax as its
 expected object type, then those control actions must fail.  In both
 the monitoring and control cases, the name of an object returned by
 an operation must be identical to the name requested by an operation.

Rose & McCloghrie [Page 16] RFC 1155 SMI May 1990

6. Definitions

         RFC1155-SMI DEFINITIONS ::= BEGIN
         EXPORTS -- EVERYTHING
                 internet, directory, mgmt,
                 experimental, private, enterprises,
                 OBJECT-TYPE, ObjectName, ObjectSyntax, SimpleSyntax,
                 ApplicationSyntax, NetworkAddress, IpAddress,
                 Counter, Gauge, TimeTicks, Opaque;
  1. - the path to the root
          internet      OBJECT IDENTIFIER ::= { iso org(3) dod(6) 1 }
          directory     OBJECT IDENTIFIER ::= { internet 1 }
          mgmt          OBJECT IDENTIFIER ::= { internet 2 }
          experimental  OBJECT IDENTIFIER ::= { internet 3 }
          private       OBJECT IDENTIFIER ::= { internet 4 }
          enterprises   OBJECT IDENTIFIER ::= { private 1 }
  1. - definition of object types
          OBJECT-TYPE MACRO ::=
          BEGIN
              TYPE NOTATION ::= "SYNTAX" type (TYPE ObjectSyntax)
                                "ACCESS" Access
                                "STATUS" Status
              VALUE NOTATION ::= value (VALUE ObjectName)
              Access ::= "read-only"
                              | "read-write"
                              | "write-only"
                              | "not-accessible"
              Status ::= "mandatory"
                              | "optional"
                              | "obsolete"
          END
  1. - names of objects in the MIB
             ObjectName ::=
                 OBJECT IDENTIFIER

Rose & McCloghrie [Page 17] RFC 1155 SMI May 1990

  1. - syntax of objects in the MIB
             ObjectSyntax ::=
                 CHOICE {
                     simple
                         SimpleSyntax,
  1. - note that simple SEQUENCEs are not directly
  2. - mentioned here to keep things simple (i.e.,
  3. - prevent mis-use). However, application-wide
  4. - types which are IMPLICITly encoded simple
  5. - SEQUENCEs may appear in the following CHOICE
                     application-wide
                         ApplicationSyntax
                 }
                SimpleSyntax ::=
                    CHOICE {
                        number
                            INTEGER,
                        string
                            OCTET STRING,
                        object
                            OBJECT IDENTIFIER,
                        empty
                            NULL
                    }
                ApplicationSyntax ::=
                    CHOICE {
                        address
                            NetworkAddress,
                        counter
                            Counter,
                        gauge
                            Gauge,
                        ticks
                            TimeTicks,
                        arbitrary
                            Opaque

Rose & McCloghrie [Page 18] RFC 1155 SMI May 1990

  1. - other application-wide types, as they are
  2. - defined, will be added here

}

  1. - application-wide types
                NetworkAddress ::=
                    CHOICE {
                        internet
                            IpAddress
                    }
                IpAddress ::=
                    [APPLICATION 0]          -- in network-byte order
                        IMPLICIT OCTET STRING (SIZE (4))
                Counter ::=
                    [APPLICATION 1]
                        IMPLICIT INTEGER (0..4294967295)
                Gauge ::=
                    [APPLICATION 2]
                        IMPLICIT INTEGER (0..4294967295)
                TimeTicks ::=
                    [APPLICATION 3]
                        IMPLICIT INTEGER (0..4294967295)
                Opaque ::=
                    [APPLICATION 4]          -- arbitrary ASN.1 value,
                        IMPLICIT OCTET STRING   --   "double-wrapped"
                END

Rose & McCloghrie [Page 19] RFC 1155 SMI May 1990

7. Acknowledgements

 This memo was influenced by three sets of contributors to earlier
 drafts:
 First, Lee Labarre of the MITRE Corporation, who as author of the
 NETMAN SMI [4], presented the basic roadmap for the SMI.
 Second, several individuals who provided valuable comments on this
 memo prior to its initial distribution:
       James R. Davin, Proteon
       Mark S. Fedor, NYSERNet
       Craig Partridge, BBN Laboratories
       Martin Lee Schoffstall, Rensselaer Polytechnic Institute
       Wengyik Yeong, NYSERNet
 Third, the IETF MIB working group:
       Karl Auerbach, Epilogue Technology
       K. Ramesh Babu, Excelan
       Lawrence Besaw, Hewlett-Packard
       Jeffrey D. Case, University of Tennessee at Knoxville
       James R. Davin, Proteon
       Mark S. Fedor, NYSERNet
       Robb Foster, BBN
       Phill Gross, The MITRE Corporation
       Bent Torp Jensen, Convergent Technology
       Lee Labarre, The MITRE Corporation
       Dan Lynch, Advanced Computing Environments
       Keith McCloghrie, The Wollongong Group
       Dave Mackie, 3Com/Bridge
       Craig Partridge, BBN (chair)
       Jim Robertson, 3Com/Bridge
       Marshall T. Rose, The Wollongong Group
       Greg Satz, cisco
       Martin Lee Schoffstall, Rensselaer Polytechnic Institute
       Lou Steinberg, IBM
       Dean Throop, Data General
       Unni Warrier, Unisys

Rose & McCloghrie [Page 20] RFC 1155 SMI May 1990

8. References

 [1] Information processing systems - Open Systems Interconnection,
     "Specification of Abstract Syntax Notation One (ASN.1)",
     International Organization for Standardization, International
     Standard 8824, December 1987.
 [2] McCloghrie K., and M. Rose, "Management Information Base for
     Network Management of TCP/IP-based Internets", RFC 1156,
     Performance Systems International and Hughes LAN Systems, May
     1990.
 [3] Case, J., M. Fedor, M. Schoffstall, and J. Davin, The Simple
     Network Management Protocol", RFC 1157, University of Tennessee
     at Knoxville, Performance Systems International, Performance
     Systems International, and the MIT Laboratory for Computer
     Science, May 1990.
 [4] LaBarre, L., "Structure and Identification of Management
     Information for the Internet", Internet Engineering Task Force
     working note, Network Information Center, SRI International,
     Menlo Park, California, April 1988.
 [5] Cerf, V., "IAB Recommendations for the Development of Internet
     Network Management Standards", RFC 1052, IAB, April 1988.
 [6] Cerf, V., "Report of the Second Ad Hoc Network Management Review
     Group", RFC 1109, IAB, August 1989.
 [7] Information processing systems - Open Systems Interconnection,
     "Specification of Basic Encoding Rules for Abstract Notation One
     (ASN.1)", International Organization for Standardization,
     International Standard 8825, December 1987.

Security Considerations

 Security issues are not discussed in this memo.

Rose & McCloghrie [Page 21] RFC 1155 SMI May 1990

Authors' Addresses

 Marshall T. Rose
 PSI, Inc.
 PSI California Office
 P.O. Box 391776
 Mountain View, CA 94039
 Phone: (415) 961-3380
 EMail: mrose@PSI.COM
 Keith McCloghrie
 The Wollongong Group
 1129 San Antonio Road
 Palo Alto, CA 04303
 Phone: (415) 962-7160
 EMail: sytek!kzm@HPLABS.HP.COM

Rose & McCloghrie [Page 22]

/data/webs/external/dokuwiki/data/pages/rfc/rfc1155.txt · Last modified: 1990/05/10 23:23 (external edit)