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Re: snmpconf PM MIB Issue #9




Thanks for this.

I think this is a good approach for a generalized solution. It works
kindof like sync() except that you get more granularity.

One of my questions was whether per-row granularity was important. It
seems the more popular strategy is to have per-row granularity thru
storageType and then the write buttons write only those that are
nonVolatile. Thus we should leave in storageType.

The other question is how we should get the write buttons? We could:
1) Do nothing and wait for the storage-type MIB to clarify the PM MIB in
the same way as it will clarify all other existing use of storageType.
(This doesn't add any dependence on the completion of the storage type
MIB).
2) Add a scalar to the PM MIB that writes all nonVolatile entries

Comments?

Steve


Juergen Schoenwaelder wrote:
> 
> >>>>> Steve Waldbusser writes:
> 
> Steve> I'm happy to replace storage type with another mechanism but
> Steve> I'd rather not invent it from scratch given that I've never
> Steve> personally had experience with this problem myself. Is there a
> Steve> generally-accepted solution to this problem? A single
> Steve> write-everything-to-nvram button? Or keep (son of) storage-type
> Steve> and add a button that only writes all storage-type=nonvolatile
> Steve> rows?
> 
> Steve> If this happens to just be a DiffServ issue, I hope someone
> Steve> will speak up. The PM MIB is designed to go well beyond
> Steve> DiffServ.
> 
> One can argue that the StorageType definition is vague as it does not
> clearly spell out when new values are written to non-volatile
> storage.
> 
> I know from talking to various people that implementors use different
> strategies to implement StorageType. I started work on an ID which
> "clarifies" the behaviour of the StorageType TC and adds some new MIB
> objects that give you a central set of "write buttons". I never got
> around to post the ID since I wanted to get more feedback first.
> 
> Feedback is welcome and if people think this is a good approach, then
> I am willing to push this forward.
> 
> /js
> 
> Network Working Group                                   J. Schoenwaelder
> Internet-Draft                                           TU Braunschweig
> Expires: October 2, 2001                                   April 3, 2001
> 
>                             Storage Type MIB
>                      draft-schoenw-storage-type-00
> 
> Status of this Memo
> 
>    This document is an Internet-Draft and is in full conformance with
>    all provisions of Section 10 of RFC2026.
> 
>    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."
> 
>    The list of current Internet-Drafts can be accessed at
>    http://www.ietf.org/ietf/1id-abstracts.txt.
> 
>    The list of Internet-Draft Shadow Directories can be accessed at
>    http://www.ietf.org/shadow.html.
> 
>    This Internet-Draft will expire on October 2, 2001.
> 
> Copyright Notice
> 
>    Copyright (C) The Internet Society (2001).  All Rights Reserved.
> 
> Abstract
> 
>    The second version of the Structure of Management Information (SMIv2)
>    introduced the StorageType textual convention in RFC 2579.  It is
>    used to describe the memory realization of rows in conceptual tables.
>    Several standards-track MIB modules make use of this convention.
>    Implementation experience shows that different approaches are used to
>    actually write conceptual rows to non-volatile memory.  This memo
>    addresses this question and provides a storage MIB module which can
>    be used to control when non-volatile rows are actually written to
>    non-volatile memory.
> 
> Schoenwaelder            Expires October 2, 2001                [Page 1]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
> Table of Contents
> 
>    1. The SNMP Management Framework  . . . . . . . . . . . . . . . .   3
>    2. StorageType Interpretations  . . . . . . . . . . . . . . . . .   4
>    3. Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .   6
>    4. Security Considerations  . . . . . . . . . . . . . . . . . . .   9
>    5. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .   9
>    6. Intellectual Property Notice . . . . . . . . . . . . . . . . .   9
>       References . . . . . . . . . . . . . . . . . . . . . . . . . .  10
>       Author's Address . . . . . . . . . . . . . . . . . . . . . . .  11
>       Full Copyright Statement . . . . . . . . . . . . . . . . . . .  12
> 
> Schoenwaelder            Expires October 2, 2001                [Page 2]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
> 1. The SNMP Management Framework
> 
>    The SNMP Management Framework presently consists of five major
>    components:
> 
>    o  An overall architecture, described in RFC 2571 [2].
> 
>    o  Mechanisms for describing and naming objects and events for the
>       purpose of management.  The first version of this Structure of
>       Management Information (SMI) is called SMIv1 and described in STD
>       16, RFC 1155 [3], STD 16, RFC 1212 [4] and RFC 1215 [5].  The
>       second version, called SMIv2, is described in STD 58, RFC 2578
>       [6], STD 58, RFC 2579 [7] and STD 58, RFC 2580 [8].
> 
>    o  Message protocols for transferring management information.  The
>       first version of the SNMP message protocol is called SNMPv1 and
>       described in STD 15, RFC 1157 [9].  A second version of the SNMP
>       message protocol, which is not an Internet standards track
>       protocol, is called SNMPv2c and described in RFC 1901 [10] and RFC
>       1906 [11].  The third version of the message protocol is called
>       SNMPv3 and described in RFC 1906 [11], RFC 2572 [12] and RFC 2574
>       [13].
> 
>    o  Protocol operations for accessing management information.  The
>       first set of protocol operations and associated PDU formats is
>       described in STD 15, RFC 1157 [9].  A second set of protocol
>       operations and associated PDU formats is described in RFC 1905
>       [14].
> 
>    o  A set of fundamental applications described in RFC 2573 [15] and
>       the view-based access control mechanism described in RFC 2575
>       [16].
> 
>    A more detailed introduction to the current SNMP Management Framework
>    can be found in RFC 2570 [17].
> 
>    Managed objects are accessed via a virtual information store, termed
>    the Management Information Base or MIB.  Objects in the MIB are
>    defined using the mechanisms defined in the SMI.
> 
>    This memo specifies a MIB module that is compliant to the SMIv2.  A
>    MIB conforming to the SMIv1 can be produced through the appropriate
>    translations.  The resulting translated MIB must be semantically
>    equivalent, except where objects or events are omitted because no
>    translation is possible (use of Counter64).  Some machine readable
>    information in SMIv2 will be converted into textual descriptions in
>    SMIv1 during the translation process.  However, this loss of machine
>    readable information is not considered to change the semantics of the
> 
> Schoenwaelder            Expires October 2, 2001                [Page 3]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>    MIB.
> 
> 2. StorageType Interpretations
> 
>    The SMIv2 introduced the StorageType textual convention which is used
>    to describe how conceptual rows are stored in memory.  Several MIBs
>    on the standards-track use this StorageType for conceptual tables
>    that support row creation.  The StorageType textual convention is
>    defined in RFC 2579 [7] as follows:
> 
>    StorageType ::= TEXTUAL-CONVENTION
>        STATUS       current
>        DESCRIPTION
>                "Describes the memory realization of a conceptual row.  A
>                row which is volatile(2) is lost upon reboot.  A row which
>                is either nonVolatile(3), permanent(4) or readOnly(5), is
>                backed up by stable storage.  A row which is permanent(4)
>                can be changed but not deleted.  A row which is readOnly(5)
>                cannot be changed nor deleted.
> 
>                If the value of an object with this syntax is either
>                permanent(4) or readOnly(5), it cannot be written.
>                Conversely, if the value is either other(1), volatile(2) or
>                nonVolatile(3), it cannot be modified to be permanent(4) or
>                readOnly(5).  (All illegal modifications result in a
>                'wrongValue' error.)
> 
>                Every usage of this textual convention is required to
>                specify the columnar objects which a permanent(4) row must
>                at a minimum allow to be writable."
>        SYNTAX       INTEGER {
>                         other(1),       -- eh?
>                         volatile(2),    -- e.g., in RAM
>                         nonVolatile(3), -- e.g., in NVRAM
>                         permanent(4),   -- e.g., partially in ROM
>                         readOnly(5)     -- e.g., completely in ROM
>                     }
> 
>    Note that the text in the DESCRIPTION clause does not make any
>    explicit statements when a conceptual row is actually written to non-
>    volatile storage.  One interpretation is that rows must be writen to
>    non-volatile storage on each set operation on one of the columnar
>    objects.  However, many implementations prefer to not write to non-
>    volatile storage on each set operation.  There are two main reasons
>    for this behavior:
> 
>    1.  Writing non-volatile storage is on some systems too time
>        consuming to do it during the set operation itself.
> 
> Schoenwaelder            Expires October 2, 2001                [Page 4]
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> Internet-Draft              Storage Type MIB                  April 2001
> 
>    2.  Writing non-volatile storage on every single set of a non-
>        volatile variable is too costly on systems that can only backup
>        complex system configurations.
> 
>    Implementations therefore use different strategies:
> 
>    1.  Some systems update the non-volatile storage on each set
>        operation.
> 
>    2.  Some systems first return a positive response to the set
>        operation and they write the modified variables to non-volatile
>        storage at some later point in time when there are no more
>        changes.
> 
>    3.  Some systems first return a positive response to the set
>        operation and they delay the actual write to non-volatile storage
>        to some external event (e.g.  shutdown of the agent, pushing of a
>        global write button).
> 
>    4.  Some systems first return a positive response to the set
>        operation and they write the modified variables when a logical
>        row operation has completed.  (For example, incomplete conceptual
>        rows are not saved in non-volatile storage until they are
>        complete and activated.)
> 
>    It seems that delayed writes to non-volatile storage are common
>    practice.  However, since this behaviour is right now completely
>    implementation dependent, there is no simple way for a management
>    application to learn how a given device implements the StorageType
>    textual convention and therefore it is unclear when a row is actually
>    written to stable storage.
> 
>    Commonly used command line interfaces of network devices also follow
>    a paradigm where explicit commands trigger the storage of the device
>    configuration (or logical parts of the configuration) in stable
>    storage.  Operational experience with these interfaces suggests that
>    it is (i) valuable to have explicit control when configuration data
>    is written to non-volatile storage and (ii) efficient to implement on
>    networking devices.
> 
>    This document therefore proposes to introduce new MIB objects which
>    can be used by management applications to control when non-volatile
>    conceptual rows are written to stable storage.  The MIB supports
>    multiple "write buttons" to support implementations which use
>    different mechanisms in different parts of the MIBs to save rows in
>    non-volatile storage.  All "write buttons" are registered in a common
>    table so that management applications can easily find them.  The
>    table is organized so that sub-agents can register rows in the table
> 
> Schoenwaelder            Expires October 2, 2001                [Page 5]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>    easily.  In addition, there is a global "write button" which
>    basically causes all write buttons in the table to be triggered.
> 
>    An alternative approach would have been to introduce "write button"
>    scalars in various MIB modules that use the StorageType textual
>    convention.  However, this leads to serious problems for management
>    applications to find the right scalars for the right set of MIB
>    objects.  Furthermore, it would be hard to realize a global "write
>    button" in a master/subagent environment without specific protocol
>    support.
> 
> 3. Definitions
> 
>    SNMP-STORAGE-MIB DEFINITIONS ::= BEGIN
> 
>    IMPORTS
>        MODULE-IDENTITY,
>        OBJECT-TYPE,
>        snmpModules,
>        Unsigned32
>         FROM SNMPv2-SMI
> 
>        DateAndTime,
>        AutonomousType
>            FROM SNMPv2-TC
> 
>        SnmpAdminString
>            FROM SNMP-FRAMEWORK-MIB;
> 
>    snmpStorageMIB MODULE-IDENTITY
>        LAST-UPDATED "200104020000Z"
>        ORGANIZATION "IETF"
>        CONTACT-INFO
>         ""
>        DESCRIPTION
>         ""
>        REVISION    "200104020000Z"
>        DESCRIPTION "The initial revision, published as RFC XXXX."
>        ::= { snmpModules xxx }
> 
>    snmpStorageObjects     OBJECT IDENTIFIER ::= { snmpStorageMIB 1 }
>    snmpStorageConformance OBJECT IDENTIFIER ::= { snmpStorageMIB 2 }
> 
>    snmpStorageGlobControl OBJECT-TYPE
>        SYNTAX   INTEGER { nop(1), write(2) }
>        MAX-ACCESS       read-write
>        STATUS   current
>        DESCRIPTION
> 
> Schoenwaelder            Expires October 2, 2001                [Page 6]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>         "This object ..."
>        ::= { snmpStorageObjects 1 }
> 
>    snmpStorageGlobStatus OBJECT-TYPE
>        SYNTAX   INTEGER {
>                     other(1),
>                     dirty(2),           -- can probably not be implemented ?
>                     writing(3),         -- perhaps we only need 'idle' and
>                     done(4)             -- 'inProgress'?
>                 }
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         "This object ..."
>        ::= { snmpStorageObjects 2 }
> 
>    snmpStorageGlobError OBJECT-TYPE
>        SYNTAX   SnmpAdminString
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         "This object contains a descriptive error message if the
>          last attempt to write global stable storage has failed."
>        ::= { snmpStorageObjects 3 }
> 
>    snmpStorageGlobErrorTime OBJECT-TYPE
>        SYNTAX   DateAndTime
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         "The data and time when the snmpStorageGlobError was last
>          updated. The value '0000000000000000'H is returned if
>          snmpStorageGlobError has not yet been updated after the
>          initialization."
>        ::= { snmpStorageObjects 4 }
> 
>    snmpStorageTable OBJECT-TYPE
>        SYNTAX   SEQUENCE OF SnmpStorageEntry
>        MAX-ACCESS       not-accessible
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageObjects 5 }
> 
>    snmpStorageEntry OBJECT-TYPE
>        SYNTAX   SnmpStorageEntry
>        MAX-ACCESS       not-accessible
>        STATUS   current
> 
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> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>        DESCRIPTION
>         ""
>        ::= { snmpStorageTable 1 }
> 
>    SnmpStorageEntry ::= SEQUENCE {
>        snmpStorageIndex         Unsigned32,
>        snmpStorageDescr         SnmpAdminString,
>        snmpStorageID            AutonomousType,
>        snmpStorageControl               INTEGER,
>        snmpStorageStatus                INTEGER,
>        snmpStorageError         SnmpAdminString,
>        snmpStorageErrorTime     DateAndTime
>    }
> 
>    snmpStorageIndex OBJECT-TYPE
>        SYNTAX   Unsigned32
>        MAX-ACCESS       not-accessible
>        STATUS   current
>        DESCRIPTION
>         "The index which uniquely identifies a row in the
>          snmpStorageTable."
>        ::= { snmpStorageEntry 1 }
> 
>    snmpStorageDescr OBJECT-TYPE
>        SYNTAX   SnmpAdminString
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageEntry 2 }
> 
>    snmpStorageID OBJECT-TYPE
>        SYNTAX   AutonomousType
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageEntry 3 }
> 
>    snmpStorageControl OBJECT-TYPE
>        SYNTAX   INTEGER { nop(1), write(2) }
>        MAX-ACCESS       read-write
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageEntry 4 }
> 
>    snmpStorageStatus OBJECT-TYPE
> 
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> 
>        SYNTAX   INTEGER { other(1), dirty(2), writing(3), done(4) }
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageEntry 5 }
> 
>    snmpStorageError OBJECT-TYPE
>        SYNTAX   SnmpAdminString
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>         ""
>        ::= { snmpStorageEntry 6 }
> 
>    snmpStorageErrorTime OBJECT-TYPE
>        SYNTAX   DateAndTime
>        MAX-ACCESS       read-only
>        STATUS   current
>        DESCRIPTION
>            ""
>        ::= { snmpStorageEntry 7 }
> 
>    -- XXX Spell out conformance definitions. Just say that the
>    -- snmpStorageTable is not required on systems that need only
>    -- a single "write button".
> 
>    END
> 
> 4. Security Considerations
> 
>    ...
> 
> 5. Acknowledgments
> 
>    ...
> 
> 6. Intellectual Property Notice
> 
>    The IETF takes no position regarding the validity or scope of any
>    intellectual property or other rights that might be claimed to
>    pertain to the implementation or use of the technology described in
>    this document or the extent to which any license under such rights
>    might or might not be available; neither does it represent that it
>    has made any effort to identify any such rights.  Information on the
>    IETF's procedures with respect to rights in standards-track and
>    standards-related documentation can be found in BCP-11.  Copies of
> 
> Schoenwaelder            Expires October 2, 2001                [Page 9]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>    claims of rights made available for publication and any assurances of
>    licenses to be made available, or the result of an attempt made to
>    obtain a general license or permission for the use of such propritary
>    rights by implementors or users of this specification can be obtained
>    from the IETF Secretariat.
> 
>    The IETF invites any interested party to bring to its attention any
>    copyrights, patents or patent applications, or other proprietary
>    rights which may cover technology that may be required to practice
>    this standard.  Please address the information to the IETF Executive
>    Director.
> 
> References
> 
>    [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
>          Levels", BCP 14, RFC 2119, March 1997.
> 
>    [2]   Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for
>          Describing SNMP Management Frameworks", RFC 2571, April 1999.
> 
>    [3]   Rose, M. and K. McCloghrie, "Structure and Identification of
>          Management Information for TCP/IP-based Internets", STD 16, RFC
>          1155, May 1990.
> 
>    [4]   Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16,
>          RFC 1212, March 1991.
> 
>    [5]   Rose, M., "A Convention for Defining Traps for use with the
>          SNMP", RFC 1215, March 1991.
> 
>    [6]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
>          M. and S. Waldbusser, "Structure of Management Information
>          Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
> 
>    [7]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
>          M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58,
>          RFC 2579, April 1999.
> 
>    [8]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
>          M. and S. Waldbusser, "Conformance Statements for SMIv2", STD
>          58, RFC 2580, April 1999.
> 
>    [9]   Case, J., Fedor, M., Schoffstall, M. and J. Davin, "A Simple
>          Network Management Protocol (SNMP)", STD 15, RFC 1157, May
>          1990.
> 
>    [10]  Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
>          "Introduction to Community-based SNMPv2", RFC 1901, January
> 
> Schoenwaelder            Expires October 2, 2001               [Page 10]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
>          1996.
> 
>    [11]  Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
>          "Transport Mappings for Version 2 of the Simple Network
>          Management Protocol (SNMPv2)", RFC 1906, January 1996.
> 
>    [12]  Case, J., Harrington, D., Presuhn, R. and B. Wijnen, "Message
>          Processing and Dispatching for the Simple Network Management
>          Protocol (SNMP)", RFC 2572, April 1999.
> 
>    [13]  Blumenthal, U. and B. Wijnen, "User-based Security Model (USM)
>          for version 3 of the Simple Network Management Protocol
>          (SNMPv3)", RFC 2574, April 1999.
> 
>    [14]  Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol
>          Operations for Version 2 of the Simple Network Management
>          Protocol (SNMPv2)", RFC 1905, January 1996.
> 
>    [15]  Levi, D., Meyer, P. and B. Stewart, "SNMP Applications", RFC
>          2573, April 1999.
> 
>    [16]  Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access
>          Control Model (VACM) for the Simple Network Management Protocol
>          (SNMP)", RFC 2575, April 1999.
> 
>    [17]  Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction
>          to Version 3 of the Internet-standard Network Management
>          Framework", RFC 2570, April 1999.
> 
> Author's Address
> 
>    Juergen Schoenwaelder
>    TU Braunschweig
>    Bueltenweg 74/75
>    38106 Braunschweig
>    Germany
> 
>    Phone: +49 531 391-3266
>    EMail: schoenw@ibr.cs.tu-bs.de
> 
> Schoenwaelder            Expires October 2, 2001               [Page 11]
> 
> Internet-Draft              Storage Type MIB                  April 2001
> 
> Full Copyright Statement
> 
>    Copyright (C) The Internet Society (2001).  All Rights Reserved.
> 
>    This document and translations of it may be copied and furnished to
>    others, and derivative works that comment on or otherwise explain it
>    or assist in its implementation may be prepared, copied, published
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>    kind, provided that the above copyright notice and this paragraph are
>    included on all such copies and derivative works.  However, this
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>    the copyright notice or references to the Internet Society or other
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> 
>    The limited permissions granted above are perpetual and will not be
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> 
>    This document and the information contained herein is provided on an
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> 
> Acknowledgement
> 
>    Funding for the RFC Editor function is currently provided by the
>    Internet Society.
> 
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