rfc1902.txt

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Network Working Group                               SNMPv2 Working Group
Request for Comments: 1902                                       J. Case
Obsoletes: 1442                                      SNMP Research, Inc.
Category: Standards Track                                  K. McCloghrie
                                                     Cisco Systems, Inc.
                                                                 M. Rose
                                            Dover Beach Consulting, Inc.
                                                           S. Waldbusser
                                          International Network Services
                                                            January 1996


                  Structure of Management Information
                          for Version 2 of the
              Simple Network Management Protocol (SNMPv2)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

1.  Introduction

   A management system contains:  several (potentially many) nodes, each
   with a processing entity, termed an agent, which has access to
   management instrumentation; at least one management station; and, a
   management protocol, used to convey management information between
   the agents and management stations.  Operations of the protocol are
   carried out under an administrative framework which defines
   authentication, authorization, access control, and privacy policies.

   Management stations execute management applications which monitor and
   control managed elements.  Managed elements are devices such as
   hosts, routers, terminal servers, etc., which are monitored and
   controlled via access to their management information.

   Management information is viewed as a collection of managed objects,
   residing in a virtual information store, termed the Management
   Information Base (MIB).  Collections of related objects are defined
   in MIB modules.  These modules are written using an adapted subset of
   OSI's Abstract Syntax Notation One (ASN.1) [1].  It is the purpose of
   this document, the Structure of Management Information (SMI), to
   define that adapted subset, and to assign a set of associated
   administrative values.




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   The SMI is divided into three parts:  module definitions, object
   definitions, and, notification definitions.

(1)  Module definitions are used when describing information modules.
     An ASN.1 macro, MODULE-IDENTITY, is used to concisely convey the
     semantics of an information module.

(2)  Object definitions are used when describing managed objects.  An
     ASN.1 macro, OBJECT-TYPE, is used to concisely convey the syntax
     and semantics of a managed object.

(3)  Notification definitions are used when describing unsolicited
     transmissions of management information.  An ASN.1 macro,
     NOTIFICATION-TYPE, is used to concisely convey the syntax and
     semantics of a notification.

1.1.  A Note on Terminology

   For the purpose of exposition, the original Internet-standard Network
   Management Framework, as described in RFCs 1155 (STD 16), 1157 (STD
   15), and 1212 (STD 16), is termed the SNMP version 1 framework
   (SNMPv1).  The current framework is termed the SNMP version 2
   framework (SNMPv2).

2.  Definitions

SNMPv2-SMI DEFINITIONS ::= BEGIN


-- the path to the root

org            OBJECT IDENTIFIER ::= { iso 3 }
dod            OBJECT IDENTIFIER ::= { org 6 }
internet       OBJECT IDENTIFIER ::= { dod 1 }

directory      OBJECT IDENTIFIER ::= { internet 1 }

mgmt           OBJECT IDENTIFIER ::= { internet 2 }
mib-2          OBJECT IDENTIFIER ::= { mgmt 1 }
transmission   OBJECT IDENTIFIER ::= { mib-2 10 }

experimental   OBJECT IDENTIFIER ::= { internet 3 }

private        OBJECT IDENTIFIER ::= { internet 4 }
enterprises    OBJECT IDENTIFIER ::= { private 1 }

security       OBJECT IDENTIFIER ::= { internet 5 }




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snmpV2         OBJECT IDENTIFIER ::= { internet 6 }

-- transport domains
snmpDomains    OBJECT IDENTIFIER ::= { snmpV2 1 }

-- transport proxies
snmpProxys     OBJECT IDENTIFIER ::= { snmpV2 2 }

-- module identities
snmpModules    OBJECT IDENTIFIER ::= { snmpV2 3 }


-- definitions for information modules

MODULE-IDENTITY MACRO ::=
BEGIN
    TYPE NOTATION ::=
                  "LAST-UPDATED" value(Update UTCTime)
                  "ORGANIZATION" Text
                  "CONTACT-INFO" Text
                  "DESCRIPTION" Text
                  RevisionPart

    VALUE NOTATION ::=
                  value(VALUE OBJECT IDENTIFIER)

    RevisionPart ::=
                  Revisions
                | empty
    Revisions ::=
                  Revision
                | Revisions Revision
    Revision ::=
                  "REVISION" value(Update UTCTime)
                  "DESCRIPTION" Text

    -- uses the NVT ASCII character set
    Text ::= """" string """"
END


OBJECT-IDENTITY MACRO ::=
BEGIN
    TYPE NOTATION ::=
                  "STATUS" Status
                  "DESCRIPTION" Text
                  ReferPart




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    VALUE NOTATION ::=
                  value(VALUE OBJECT IDENTIFIER)

    Status ::=
                  "current"
                | "deprecated"
                | "obsolete"

    ReferPart ::=
                "REFERENCE" Text
              | empty

    Text ::= """" string """"
END


-- names of objects

ObjectName ::=
    OBJECT IDENTIFIER

NotificationName ::=
    OBJECT IDENTIFIER

-- syntax of objects

ObjectSyntax ::=
    CHOICE {
        simple
            SimpleSyntax,

          -- note that SEQUENCEs for conceptual tables and
          -- rows are not mentioned here...

        application-wide
            ApplicationSyntax
    }


-- built-in ASN.1 types

SimpleSyntax ::=
    CHOICE {
        -- INTEGERs with a more restrictive range
        -- may also be used
        integer-value               -- includes Integer32
            INTEGER (-2147483648..2147483647),




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        -- OCTET STRINGs with a more restrictive size
        -- may also be used
        string-value
            OCTET STRING (SIZE (0..65535)),

        objectID-value
            OBJECT IDENTIFIER
    }


-- indistinguishable from INTEGER, but never needs more than
-- 32-bits for a two's complement representation
Integer32 ::=
    [UNIVERSAL 2]
        IMPLICIT INTEGER (-2147483648..2147483647)


-- application-wide types

ApplicationSyntax ::=
    CHOICE {
        ipAddress-value
            IpAddress,

        counter-value
            Counter32,

        timeticks-value
            TimeTicks,

        arbitrary-value
            Opaque,

        big-counter-value
            Counter64,

        unsigned-integer-value  -- includes Gauge32
            Unsigned32
    }

-- in network-byte order
-- (this is a tagged type for historical reasons)
IpAddress ::=
    [APPLICATION 0]
        IMPLICIT OCTET STRING (SIZE (4))

-- this wraps
Counter32 ::=



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    [APPLICATION 1]
        IMPLICIT INTEGER (0..4294967295)

-- this doesn't wrap
Gauge32 ::=
    [APPLICATION 2]
        IMPLICIT INTEGER (0..4294967295)

-- an unsigned 32-bit quantity
-- indistinguishable from Gauge32
Unsigned32 ::=
    [APPLICATION 2]
        IMPLICIT INTEGER (0..4294967295)

-- hundredths of seconds since an epoch
TimeTicks ::=
    [APPLICATION 3]
        IMPLICIT INTEGER (0..4294967295)

-- for backward-compatibility only
Opaque ::=
    [APPLICATION 4]
        IMPLICIT OCTET STRING

-- for counters that wrap in less than one hour with only 32 bits
Counter64 ::=
    [APPLICATION 6]
        IMPLICIT INTEGER (0..18446744073709551615)


-- definition for objects

OBJECT-TYPE MACRO ::=
BEGIN
    TYPE NOTATION ::=
                  "SYNTAX" Syntax
                  UnitsPart
                  "MAX-ACCESS" Access
                  "STATUS" Status
                  "DESCRIPTION" Text
                  ReferPart
                  IndexPart
                  DefValPart

    VALUE NOTATION ::=
                  value(VALUE ObjectName)

    Syntax ::=



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                  type(ObjectSyntax)
                | "BITS" "{" Kibbles "}"
    Kibbles ::=
                  Kibble
                | Kibbles "," Kibble
    Kibble ::=
                 identifier "(" nonNegativeNumber ")"

    UnitsPart ::=
                  "UNITS" Text
                | empty

    Access ::=
                  "not-accessible"
                | "accessible-for-notify"
                | "read-only"
                | "read-write"
                | "read-create"

    Status ::=
                  "current"
                | "deprecated"
                | "obsolete"