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Versions: 00                                                            
  Internet Draft       Instance Reservation MIB   September 16, 1996


       Definitions of Managed Objects for Instance Reservation

                          September 16, 1996


                <draft-ietf-resmib-instresmib-00.txt>


                             David Battle
                         SNMP Research, Inc.
                           battle@snmp.com

                            Ulrich Haebel
                Siemens Nixdorf Informationssysteme AG
                       Ulrich.Haebel@mch.sni.de






                         Status of this Memo

  This document is an Internet-Draft.  Internet-Drafts are working
  documents of the Internet Engineering Task Force (IETF), its
  areas, and its working groups.  Note that other groups may also
  distribute working documents as Internet-Drafts.

  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.''

  To learn the current status of any Internet-Draft, please check
  the ``1id-abstracts.txt'' listing contained in the Internet-
  Drafts Shadow Directories on ds.internic.net (US East Coast),
  nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or
  munnari.oz.au (Pacific Rim).

  SNMP Research hereby covenants that it will not assert any claims
  in this draft, any continuations, divisions, or continuations-in-
  part of the foregoing against any party that makes, uses, sells,
  imports, or offers for sale, an implementation of an IETF
  standards-track MIB module that includes SNMP Research's





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  contributed instance reservation technology, or any derivative of
  that contribution, provided that the MIB module is employed to
  implement the Internet-standard network management framework.
  Such grant of rights is limited in that it does not include a
  right to incorporate such SNMP Research instance reservation
  technology into proprietary MIB modules.

  This grant of rights will permanently terminate with respect to
  any party (and to any subsidiary of a party) that asserts a patent
  it owns or controls, either directly or indirectly, against SNMP
  Research or any of its subsidiaries for implementation of, or
  operation of any system utilizing, instance reservation
  technology.  The termination of rights will occur as of the date
  the patent is asserted against SNMP Research.

  1.  Abstract

  This memo defines an experimental portion of the Management
  Information Base (MIB) for use with network management protocols
  in the Internet community. In particular, it describes a basic set
  of managed objects for instance reservation in other MIB tables.

  This memo does not specify a standard for the Internet community.

  2.  The SNMPv2 Network Management Framework

  The SNMPv2 Network Management Framework consists of four major
  components.  They are:

  o    STD 17, RFC 1213 [1] defines MIB-II, the core set of managed
       objects for the Internet suite of protocols.

  o    RFC 1902 Structure of Management Information for Version 2 of
       the Simple Network Management Protocol (SNMPv2)

  o    RFC 1903 Textual Conventions for Version 2 of the Simple
       Network Management Protocol (SNMPv2)

  o    RFC 1904 Conformance Statements for Version 2 of the Simple
       Network Management Protocol (SNMPv2)

  o    RFC 1905 Protocol Operations for Version 2 of the Simple
       Network Management Protocol (SNMPv2)

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  o    RFC 1906 Transport Mappings for Version 2 of the Simple
       Network Management Protocol (SNMPv2)

  o    RFC 1907 Management Information Base for Version 2 of the
       Simple Network Management Protocol (SNMPv2)

  o    RFC 1908 Coexistence between Version 1 and Version 2 of the
       Internet-standard Network Management Framework


  The Framework permits new objects to be defined for the purpose of
  experimentation and evaluation.


  2.1.  Object Definitions

  Managed objects are accessed via a virtual information store,
  termed the Management Information Base or MIB. Objects in the MIB
  are defined using the subset of Abstract Syntax Notation One
  (ASN.1) defined in the SMI[2]. In particular, each object type is
  named by an OBJECT IDENTIFIER, an administratively assigned name.
  The object type together with an object instance serves to
  uniquely identify a specific instantiation of the object. For
  human convenience, we often use a textual string, termed the
  object descriptor, to refer to the object type.

  3.  Overview

  Traditionally SNMP agents have been "monolithic" in nature,
  meaning that a single linked module was used to represent the
  entire MIB for a particular entity.  In recent years several
  "extensible agent" technologies have come to exist which split the
  MIB among several distinct linked modules, typically called
  subagents.  The existance of these subagent modules has created
  the need for a mechanism by when different subagents may
  coordinate instances in mib tables in such a way that each
  subagent can perform its function without collisions occuring when
  more than one subagent tries to present the same instance of a
  particualar managed object.

  This draft is concerned primarily with providing a simple
  mechanism by which subagents can "reserve" instances in certain
  tables for their own use and find out about reservations made by
  other subagents.  This approach was taken to insure ease and speed
  of implementation, while allowing room for future growth.





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  4.  The Structure of the MIB

  The instance reservation mib consists of three tables
  (instanceTable, allocInstTable, and maxInstTable).  The tables are
  used together to allow subagents to reserve particular instances
  (rows) in other SNMP tables.  All of the objects in the mib are
  read only or not accessible.  Subagents reserve instances by
  asking questions of the form "which instance should I use" or "may
  I reserve this instance" (that is, via GET requests) rather than
  making statements such as "I want to reserve this instance" (using
  SET requests).  These get requests do the actual work of making
  the reservation.  Making reservations using this method has the
  following advantages:

     -  Reservations may be done in a single exchange, since the
        return value from the get may be used to return reservation
        information.  Since sets return no new information other
        than success or failure, a set and a subsequent get
        would be required to reserve an instance, then return
        instance information.

     -  Problems with locking and simultaneous access associated
        with sets in multithreaded agents are avoided.

  The table instanceTable reflects the state of the instance
  reservation table. It is used to request reservation of a specific
  row of a given table or get information about what rows are
  reserved.  instanceTable is indexed by two Object Identifiers, the
  OID of the table in which an instance is to be reserved, and the
  OID which is formed by concatenating the indices for the row being
  reserved.  instanceUsed and instanceNotUsed are the only two
  accessible objects.  A getexact or getnext on the instanceUsed
  object return an indication of whether a particular instance is in
  use or has been used in the past (instances which have never been
  used do not show up in the table at all).  A getexact on an
  instanceUsed object which is not currently in use will reserve
  that instance, and return either a onceUsed or neverUsed
  indication.  Future queries about that instance will return the
  "reserved" state.  Thus, if a subagent knows which instance it
  wants, it does a getexact on the instanceTable supplying the OIDs
  of the table and the desired instance.  If the return value
  indicates that the instance is not in use, the subagent may
  immediately start using it.  A getnext will query whether an
  instance is in use without reserving that instance.  The
  instanceNotUsed object (indexed by the same OIDs as instanceUsed)





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  is used to free a row reservation using a getexact operation in
  the same fashion (as instanceUsed).  Getnext operations on
  instanceNotUsed return the same information as getnext operations
  on instanceUsed.


  The second table (allocInstTable) is used when a subagent does not
  know which instance in a given table it wants to allocate.
  allocInstTable is indexed by algorithm, OID of the table from
  which an instance is to be allocated, and instance type to
  allocate.  A getexact operation on allocInstInstance causes an
  instance allocation and reservation to occur  The algorithm
  specified, either firstNeverUsed or firstNotCurrentlyUsed,
  specifies to the entity implementing the mib which type of
  instance to reserve.  The instance type is formed by building an
  oid with the first field specifying the number of indices, and
  each subsequent field spcifying the enumerated type of the indices
  for the row to be allocated.  Getnext operations on this table
  will always show it empty.

  The third table (maxInstTable) is used by subagents which want to
  use instanceTable (the first table in this mib) to directly
  request an instance, but which first need to inquire about the
  largest instance already in use.  This table is indexed by
  algorithm and the OID for the table for which an instance is
  requested.  Algorithm is specified as largestEverUsed or
  largestCurrentlyUsed. Getexact or getnext operations on
  maxInstInstance return the lexicographically largest instance
  currently (or ever) used in the indicated table.  Unlike the
  previous two tables, getexact and getnext operations have no side
  effects.



  5.  Definitions

  INSTANCEREP-MIB DEFINITIONS ::= BEGIN

  IMPORTS
      MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
      ObjectName, Integer32, Counter32
          FROM SNMPv2-SMI;


  instanceRep MODULE-IDENTITY





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      LAST-UPDATED "9605071655Z"
      ORGANIZATION "SNMP Research, Inc."
      CONTACT-INFO "David Battle
            Postal: SNMP Research, Inc.
                    3001 Kimberlin Heights Road
                    Knoxville, TN  37920
            Tel:    +1 423 573 1434
            E-Mail: battle@snmp.com"
      DESCRIPTION  "This module describes a mib for reserving instances in
                    various mib tables for use by extensible agent systems."
          ::= { enterprises 99 12 17 }



  -- The instance Group

  instance OBJECT IDENTIFIER ::= { instanceRep 1 }

  -- used as a prefix for OIDs describing a particular instance
  instanceInstanceBase OBJECT IDENTIFIER ::= { instanceRep 2 }

  -- used as a prefix for OIDs describing instance types
  instanceTypeBase OBJECT IDENTIFIER ::= { instanceRep 3 }

  instanceTable OBJECT-TYPE
      SYNTAX     SEQUENCE OF InstanceEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "A table of reserved instances containing presently and
                   historically reserved instances.  Different contexts may be
                   used by different subagents in allocating instances so that,
                   for example, only a subagent which allocates an instance may
                   release it."
  ::= { instance 1 }

  instanceEntry OBJECT-TYPE
      SYNTAX     InstanceEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "An entry describing a particular reserved (or previously
                   reserved) instance containing objects which describe the
                   instance's current state."
      INDEX { instanceObject, IMPLIED instanceInstance }
  ::= { instanceTable 1 }
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  InstanceEntry ::= SEQUENCE {
      instanceObject       OBJECT IDENTIFIER,
      instanceInstance     OBJECT IDENTIFIER,
      instanceUsed         INTEGER,
      instanceNotUsed      INTEGER
  }

  instanceObject OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The oid of the table to be associated with the allocated
                   instance.  This should be the oid of the SEQUENCE, not
                   the oid of any particular object."
  ::= { instanceEntry 1 }

  instanceInstance OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The instance to be allocated or released encoded as a oid.
                   The instance is prefixed with the instanceInstanceBase oid
                   to ensure that it is a legal oid."
  ::= { instanceEntry 2 }

  instanceUsed OBJECT-TYPE
      SYNTAX     INTEGER
                    {
                        neverUsed(1),
                        onceUsed(2),
                        reserved(3)
                    }
      MAX-ACCESS read-only
      STATUS     current
      DESCRIPTION "The state of the allocated instance as indicated by the
                   state table below.  A get-exact operation on this
                   object causes the indicated state transitions.  The state
                   returned is indicated as a separate column in the state
                   table."
  ::= { instanceEntry 3 }

  --
  -- Operation:        Get-Exact on instanceUsed    Get-Exact on instanceNotUsed
  --
  -- Current State  State Returned  State Entered  State Returned  State Entered





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  -- neverUsed      neverUsed       reserved       NULL            neverUsed
  -- onceUsed       onceUsed        reserved       onceUsed        onceUsed
  -- reserved       reserved        reserved       onceUsed        onceUsed
  --
  -- The idea is that subagents will use a get-exact on a particular instance of
  -- instanceUsed to allocate a row and a get-exact on a particular instance of
  -- instanceNotUsed in order to free the row.  The State Returned column
  -- indicates what should be returned for get-exact.  For get-next the
  -- current state should be returned and should not be changed.  The subagent
  -- can tell whether the instance we succesfully allocated by looking at
  -- the state returned from the get-exact; neverUsed or onceUsed means success.
  -- reserved means failure (ie it was already reserved).
  --
  -- NULL is used above to indicate that in this situation the agent should
  -- behave as though the instance does not exist.
  --
  -- Note also that the instance reservation mib may be implemented in such
  -- a way that only get-exacts in a certain "context" will change the
  -- state variables instanceUsed and instanceNotUsed.  instanceUsed and
  -- instanceNotUsed are shadow objects which always match each other in
  -- their internal value.
  --


  instanceNotUsed OBJECT-TYPE
      SYNTAX     INTEGER
                    {
                        neverUsed(1),
                        onceUsed(2),
                        reserved(3)
                    }
      MAX-ACCESS read-only
      STATUS     current
      DESCRIPTION "The state of the allocated instance as indicated by the
                   state table above.  A get-exact operation on this
                   object causes the indicated state transitions.  The state
                   returned is indicated as a separate column in the state
                   table."
  ::= { instanceEntry 4 }

  allocInstTable OBJECT-TYPE
      SYNTAX     SEQUENCE OF AllocInstEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "An ephemeral list used for allocation of instances.  Entries





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                   persist only long enough to return a value, then disappear.
                   Different contexts may be used by different subagents in
                   allocating instances so that, for example, only a subagent
                   which allocates an instance may release it."
  ::= { instance 2 }

  allocInstEntry OBJECT-TYPE
      SYNTAX     AllocInstEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "An entry used for allocating instances containing objects
                   need for the description of the variety of instance to be
                   allocated."
      INDEX { allocInstAlgorithm, allocInstObject, IMPLIED allocInstType }
  ::= { allocInstTable 1 }

  AllocInstEntry ::= SEQUENCE {
      allocInstAlgorithm   INTEGER,
      allocInstObject      OBJECT IDENTIFIER,
      allocInstType        OBJECT IDENTIFIER,
      allocInstInstance    OBJECT IDENTIFIER
  }

  allocInstAlgorithm OBJECT-TYPE
      SYNTAX     INTEGER {
                    firstNeverUsed(1),
                    firstNotCurrentlyUsed(2)
                  }
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The algorithm to be used in allocating the instance."
  ::= { allocInstEntry 1 }

  allocInstObject OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The oid of the table to be associated with the allocated
                   instance.  This should be the oid of the SEQUENCE, not
                   the oid of any particular object."
  ::= { allocInstEntry 2 }

  allocInstType OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS not-accessible





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      STATUS     current
      DESCRIPTION "The type of instance to be allocated.  The initial portion
                   of this oid consists of instanceTypeBase.  The subsequent
                   sub-identifiers have the following meaning:
                   Sub-Id Value          Meaning
                     1      n    total number of indices in the instance
                     2     type  the type of the first index as indicated below
                     x     type  the type of the (x-1)th index as indicated below
                     n+1   type  the type of the last index as indicated below

                   Value   Type of Index
                     1       INTEGER
                     2       ..."
  ::= { allocInstEntry 3 }

  allocInstInstance OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS read-only
      STATUS     current
      DESCRIPTION "A get-exact request on this object returns an instance
                   encoded as an oid which was allocated according to the
                   algorithm specified in the allocInstAlgorithm index.  The
                   allocated instance will be of the type indicated by the
                   allocInstType index and will be associated with the table
                   indicated by allocInstObject.  When an instance is allocated
                   using this table it causes a cooresponding entry to appear
                   in the instanceTable."
  ::= { allocInstEntry 4 }


  maxInstTable OBJECT-TYPE
      SYNTAX     SEQUENCE OF AllocInstEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "A table of the maximum instances currently reserved."
  ::= { instance 3 }

  maxInstEntry OBJECT-TYPE
      SYNTAX     MaxInstEntry
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "An entry describing the maximum instance for a particular
                   table."
      INDEX { maxInstAlgorithm, maxInstObject }
  ::= { maxInstTable 1 }





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  MaxInstEntry ::= SEQUENCE {
      maxInstAlgorithm   INTEGER,
      maxInstObject      OBJECT IDENTIFIER,
      maxInstInstance    OBJECT IDENTIFIER
  }

  maxInstAlgorithm OBJECT-TYPE
      SYNTAX     INTEGER {
                    largestEverUsed(1),
                    largestCurrentlyUsed(2)
                  }
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The algorithm to be used in computing the maximum instance."
  ::= { maxInstEntry 1 }

  maxInstObject OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION "The oid of the table for which the maximum instance should
                   be computed.  This should be the oid of the SEQUENCE, not
                   the oid of any particular object."
  ::= { maxInstEntry 2 }

  maxInstInstance OBJECT-TYPE
      SYNTAX     OBJECT IDENTIFIER
      MAX-ACCESS read-only
      STATUS     current
      DESCRIPTION "The largest instance reserved in the indicated table
                   computed according to the indicated algorithm.  Items
                   in the onceUsed state are not considered for the
                   largestCurrentlyUsed algorithm, while they are considered
                   for the largestEverUsed algorithm.  The value of this object
                   will be identical to the value of of the appropriate
                   instance of the instanceInstance object."

  ::= { maxInstEntry 4 }

  END




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  6.  References

  [1]  McCloghrie, K., and M. Rose, Editors, "Management Information
       Base for Network Management of TCP/IP-based internets: MIB-
       II", STD 17, RFC 1213, Hughes LAN Systems, Performance
       Systems International, March 1991.

  [2]  Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
       "Structure of Management Information for Version 2 of the
       Simple Network Mana" gement Protocol (SNMPv2)" , RFC 1902,
       SNMP Research, Inc., Cisco Systems, Dover Beach Consulting,
       Inc., Carnegie Mello n University, January 1996.

  7.  Security Considerations

  Security issues are not discussed in this memo.


  8.  Authors' Addresses

       David Battle
       SNMP Research, Inc.
       3001 Kimberlin Heights Rd.
       Knoxville, TN  37920-9716
       US

       Phone: +1 423 573 1434
       Email: battle@snmp.com

       Ulrich Haebel
       Siemens Nixdorf Informationssysteme AG
       Otto-Hahn-Ring 6
       81739 Muenchen
       Germany

       Phone: +49 89 636 42141
       Email: Ulrich.Haebel@mch.sni.de







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  Table of Contents


  1 Abstract ..................................................    2
  2 The SNMPv2 Network Management Framework ...................    2
  2.1 Object Definitions ......................................    3
  3 Overview ..................................................    3
  4 The Structure of the MIB ..................................    4
  5 Definitions ...............................................    5
  6 References ................................................   12
  7 Security Considerations ...................................   12
  8 Authors' Addresses ........................................   12
































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