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rfc:rfc2856

Network Working Group A. Bierman Request for Comments: 2856 K. McCloghrie Category: Standards Track Cisco Systems, Inc.

                                                           R. Presuhn
                                                   BMC Software, Inc.
                                                            June 2000
    Textual Conventions for Additional High Capacity Data Types

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.

Copyright Notice

 Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

 This memo specifies new textual conventions for additional high
 capacity data types, intended for SNMP implementations which already
 support the Counter64 data type. The definitions contained in this
 document represent a short term solution which may be deprecated in
 the future.

Table of Contents

 1 The SNMP Management Framework .................................  2
 2 Overview ......................................................  3
 2.1 Short Term and Long Term Objectives .........................  3
 2.2 Limitations of the Textual Convention Approach ..............  3
 3 New Textual Conventions .......................................  4
 3.1 CounterBasedGauge64 .........................................  4
 3.2 ZeroBasedCounter64 ..........................................  4
 4 Definitions ...................................................  4
 5 Intellectual Property .........................................  7
 6 References ....................................................  7
 7 Security Considerations .......................................  9
 8 Authors' Addresses ............................................  9
 9 Full Copyright Statement ...................................... 10

Bierman, et al. Standards Track [Page 1] RFC 2856 High Capacity Data Types June 2000

1. The SNMP Management Framework

 The SNMP Management Framework presently consists of five major
 components:
 o   An overall architecture, described in RFC 2571 [RFC2571].
 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 [RFC1155], STD 16, RFC 1212 [RFC1212] and RFC 1215
     [RFC1215].  The second version, called SMIv2, is described in STD
     58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58,
     RFC 2580 [RFC2580].
 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 [RFC1157].  A second version of the
     SNMP message protocol, which is not an Internet standards track
     protocol, is called SNMPv2c and described in RFC 1901 [RFC1901]
     and RFC 1906 [RFC1906].  The third version of the message
     protocol is called SNMPv3 and described in RFC 1906 [RFC1906],
     RFC 2572 [RFC2572] and RFC 2574 [RFC2574].
 o   Protocol operations for accessing management information. The
     first set of protocol operations and associated PDU formats is
     described in STD 15, RFC 1157 [RFC1157].  A second set of
     protocol operations and associated PDU formats is described in
     RFC 1905 [RFC1905].
 o   A set of fundamental applications described in RFC 2573 [RFC2573]
     and the view-based access control mechanism described in RFC 2575
     [RFC2575].
 A more detailed introduction to the current SNMP Management Framework
 can be found in RFC 2570 [RFC2570].
 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.  The
 textual conventions defined in this MIB module cannot be translated
 to SMIv1 since the Counter64 type does not exist in SMIv1.

Bierman, et al. Standards Track [Page 2] RFC 2856 High Capacity Data Types June 2000

2. Overview

 The Structure of Management Information [RFC2578] does not explicitly
 address the question of how to represent integer objects other than
 counters that would require up to 64 bits to provide the necessary
 range and precision.  There are MIBs in progress targeted for the
 standards track, which need such data types. This memo specifies a
 short term solution, using textual conventions, to meet these needs.

2.1. Short Term and Long Term Objectives

 There is an immediate need to provide a Gauge64 data type, similar in
 semantics to the Gauge32 data type, in order to support common data
 representations such as:
  1. a snapshot of a Counter64 at a given moment, e.g., history ring

buffer

  1. the difference between two Counter64 values
 There is also an immediate need for a 64-bit zero-based counter type,
 similar in semantics to the ZeroBasedCounter32 TC defined in the
 RMON-2 MIB [RFC2021].
 Both of these textual conventions should use a base type of Gauge64
 or Unsigned64, but such a base type is not available.  Until such a
 base type is defined and deployed, these temporary textual
 conventions (which use a base type of Counter64) will be used in MIBs
 which require unsigned 64-bit data types.
 In order to be backward compatible with existing implementations of
 Counter64, the ASN.1 encoding of unsigned 64-bit data types must be
 identical to the encoding of Counter64 objects, i.e., identified by
 the [APPLICATION 6] ASN.1 tag.
 Note that the textual conventions defined in this document represent
 a limited and short-term solution to the problem.  These textual
 conventions may be deprecated as a long term solution is defined and
 deployed to replace them.  A MIB object which uses either of these
 textual conventions may also eventually have to be deprecated.

2.2. Limitations of the Textual Convention Approach

 New unsigned data types with textual conventions based on the
 Counter64 tag, instead of a new (or other existing) ASN.1 tag have
 some limitations:

Bierman, et al. Standards Track [Page 3] RFC 2856 High Capacity Data Types June 2000

  1. The MAX-ACCESS of the TC must be read-only, because the MAX-ACCESS

of the underlying Counter64 type is read-only.

  1. No sub-range can be specified on the TC-derived types, because

sub-ranges are not allowed on Counter64 objects.

  1. No DEFVAL clause can be specified for the TC-derived types,

because DEFVALs are not allowed on Counter64 objects.

  1. The TC-derived types cannot be used in an INDEX clause, because

there is no INDEX clause mapping defined for objects of type

    Counter64.

3. New Textual Conventions

 The following textual conventions are defined to support unsigned
 64-bit data types.

3.1. CounterBasedGauge64

 This textual convention defines a 64-bit gauge, but defined with
 Counter64 syntax, since no Gauge64 or Unsigned64 base type is
 available in SMIv2.
 This TC is used for storing the difference between two Counter64
 values, or simply storing a snapshot of a Counter64 value at a given
 moment in time.

3.2. ZeroBasedCounter64

 This textual convention defines a 64-bit counter with an initial
 value of zero, instead of an arbitrary initial value.
 This TC is used for counter objects in tables which are instantiated
 by management application action.

4. Definitions

 HCNUM-TC DEFINITIONS ::= BEGIN
 IMPORTS
   MODULE-IDENTITY, mib-2, Counter64
       FROM SNMPv2-SMI
   TEXTUAL-CONVENTION
       FROM SNMPv2-TC;
 hcnumTC MODULE-IDENTITY
   LAST-UPDATED "200006080000Z"

Bierman, et al. Standards Track [Page 4] RFC 2856 High Capacity Data Types June 2000

   ORGANIZATION "IETF OPS Area"
   CONTACT-INFO
         "        E-mail: mibs@ops.ietf.org
                  Subscribe: majordomo@psg.com
                    with msg body: subscribe mibs
                  Andy Bierman
                  Cisco Systems Inc.
                  170 West Tasman Drive
                  San Jose, CA 95134 USA
                  +1 408-527-3711
                  abierman@cisco.com
                  Keith McCloghrie
                  Cisco Systems Inc.
                  170 West Tasman Drive
                  San Jose, CA 95134 USA
                  +1 408-526-5260
                  kzm@cisco.com
                  Randy Presuhn
                  BMC Software, Inc.
                  Office 1-3141
                  2141 North First Street
                  San Jose,  California 95131 USA
                  +1 408 546-1006
                  rpresuhn@bmc.com"
   DESCRIPTION
         "A MIB module containing textual conventions
          for high capacity data types. This module
          addresses an immediate need for data types not directly
          supported in the SMIv2. This short-term solution
          is meant to be deprecated as a long-term solution
          is deployed."
   REVISION        "200006080000Z"
   DESCRIPTION
         "Initial Version of the High Capacity Numbers
          MIB module, published as RFC 2856."
   ::= { mib-2 78 }
 CounterBasedGauge64 ::= TEXTUAL-CONVENTION
   STATUS       current
   DESCRIPTION
         "The CounterBasedGauge64 type represents a non-negative
         integer, which may increase or decrease, but shall never
         exceed a maximum value, nor fall below a minimum value. The
         maximum value can not be greater than 2^64-1
         (18446744073709551615 decimal), and the minimum value can

Bierman, et al. Standards Track [Page 5] RFC 2856 High Capacity Data Types June 2000

         not be smaller than 0.  The value of a CounterBasedGauge64
         has its maximum value whenever the information being modeled
         is greater than or equal to its maximum value, and has its
         minimum value whenever the information being modeled is
         smaller than or equal to its minimum value.  If the
         information being modeled subsequently decreases below
         (increases above) the maximum (minimum) value, the
         CounterBasedGauge64 also decreases (increases).
         Note that this TC is not strictly supported in SMIv2,
         because the 'always increasing' and 'counter wrap' semantics
         associated with the Counter64 base type are not preserved.
         It is possible that management applications which rely
         solely upon the (Counter64) ASN.1 tag to determine object
         semantics will mistakenly operate upon objects of this type
         as they would for Counter64 objects.
         This textual convention represents a limited and short-term
         solution, and may be deprecated as a long term solution is
         defined and deployed to replace it."
   SYNTAX Counter64
 ZeroBasedCounter64 ::= TEXTUAL-CONVENTION
   STATUS current
   DESCRIPTION
         "This TC describes an object which counts events with the
         following semantics: objects of this type will be set to
         zero(0) on creation and will thereafter count appropriate
         events, wrapping back to zero(0) when the value 2^64 is
         reached.
         Provided that an application discovers the new object within
         the minimum time to wrap it can use the initial value as a
         delta since it last polled the table of which this object is
         part.  It is important for a management station to be aware
         of this minimum time and the actual time between polls, and
         to discard data if the actual time is too long or there is
         no defined minimum time.
         Typically this TC is used in tables where the INDEX space is
         constantly changing and/or the TimeFilter mechanism is in
         use.
         Note that this textual convention does not retain all the
         semantics of the Counter64 base type. Specifically, a
         Counter64 has an arbitrary initial value, but objects
         defined with this TC are required to start at the value

Bierman, et al. Standards Track [Page 6] RFC 2856 High Capacity Data Types June 2000

         zero.  This behavior is not likely to have any adverse
         effects on management applications which are expecting
         Counter64 semantics.
         This textual convention represents a limited and short-term
         solution, and may be deprecated as a long term solution is
         defined and deployed to replace it."
   SYNTAX Counter64
 END

5. Intellectual Property

 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
 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
 proprietary 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.

6. References

 [RFC1155]   Rose, M. and K. McCloghrie, "Structure and Identification
             of Management Information for TCP/IP-based Internets",
             STD 16, RFC 1155, May 1990.
 [RFC1157]   Case, J., Fedor, M., Schoffstall, M. and J. Davin,
             "Simple Network Management Protocol", STD 15, RFC 1157,
             May 1990.
 [RFC1212]   Rose, M. and K. McCloghrie, "Concise MIB Definitions",
             STD 16, RFC 1212, March 1991.
 [RFC1215]   Rose, M., "A Convention for Defining Traps for use with
             the SNMP", RFC 1215, March 1991.

Bierman, et al. Standards Track [Page 7] RFC 2856 High Capacity Data Types June 2000

 [RFC1901]   Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
             "Introduction to Community-based SNMPv2", RFC 1901,
             January 1996.
 [RFC1905]   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.
 [RFC1906]   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.
 [RFC2021]   Waldbusser, S., "Remote Network Monitoring MIB (RMON-2)",
             RFC 2021, January 1997.
 [RFC2026]   Bradner, S., "The Internet Standards Process -- Revision
             3", BCP 9, RFC 2026, October 1996.
 [RFC2570]   Case, J., Mundy, R., Partain, D. and B. Stewart,
             "Introduction to Version 3 of the Internet-standard
             Network Management Framework", RFC 2570, April 1999.
 [RFC2571]   Harrington, D., Presuhn, R. and B. Wijnen, "An
             Architecture for Describing SNMP Management Frameworks",
             RFC 2571, April 1999.
 [RFC2572]   Case, J., Harrington D., Presuhn R. and B. Wijnen,
             "Message Processing and Dispatching for the Simple
             Network Management Protocol (SNMP)", RFC 2572, April
             1999.
 [RFC2573]   Levi, D., Meyer, P. and B. Stewart, "SNMPv3
             Applications", RFC 2573, April 1999.
 [RFC2574]   Blumenthal, U. and B. Wijnen, "User-based Security Model
             (USM) for version 3 of the Simple Network Management
             Protocol (SNMPv3)", RFC 2574, April 1999.
 [RFC2575]   Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based
             Access Control Model (VACM) for the Simple Network
             Management Protocol (SNMP)", RFC 2575, April 1999.
 [RFC2578]   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.

Bierman, et al. Standards Track [Page 8] RFC 2856 High Capacity Data Types June 2000

 [RFC2579]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
             Rose, M. and S. Waldbusser, "Textual Conventions for
             SMIv2", STD 58, RFC 2579, April 1999.
 [RFC2580]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
             Rose, M. and S. Waldbusser, "Conformance Statements for
             SMIv2", STD 58, RFC 2580, April 1999.

7. Security Considerations

 This module does not define any management objects. Instead, it
 defines a set of textual conventions which may be used by other MIB
 modules to define management objects.
 Meaningful security considerations can only be written in the modules
 that define management objects.

8. Authors' Addresses

 Andy Bierman
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA 95134 USA
 Phone: +1 408-527-3711
 EMail: abierman@cisco.com
 Keith McCloghrie
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA 95134 USA
 Phone: +1 408-526-5260
 EMail: kzm@cisco.com
 Randy Presuhn
 BMC Software, Inc.
 Office 1-3141
 2141 North First Street
 San Jose,  California 95131 USA
 Phone: +1 408 546-1006
 EMail: rpresuhn@bmc.com

Bierman, et al. Standards Track [Page 9] RFC 2856 High Capacity Data Types June 2000

9. Full Copyright Statement

 Copyright (C) The Internet Society (2000).  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
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Bierman, et al. Standards Track [Page 10]

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