High Capacity Textual Conventions for MIB Modules Using

Performance History Based on 15 Minute Intervals

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 © The Internet Society (2004). All Rights Reserved.

Abstract

This document presents a set of High Capacity Textual Conventions for use in MIB modules which require performance history based upon 15 minute intervals. The Textual Conventions defined in this document extend the conventions presented in RFC 3593 to 64 bit resolution using the conventions presented in RFC 2856.

Table of Contents

   1.  The Internet-Standard Management Framework . . . . . . . . . .  2
   2.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
   3.  Definitions. . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Intellectual Property Statement. . . . . . . . . . . . . . . .  8
   5.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
       5.1.  Normative References . . . . . . . . . . . . . . . . . .  8
       5.2.  Informative References . . . . . . . . . . . . . . . . .  9
   6.  Security Considerations. . . . . . . . . . . . . . . . . . . . 10
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10
   9.  Full Copyright Statement . . . . . . . . . . . . . . . . . . . 11

1. The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410].

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580].

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

2. Overview

In cases where a manager must obtain performance history data about the behavior of equipment it manages, several strategies can be followed in the design of a MIB module that represents the managed equipment, including:

• The agent counts events on a continuous basis and, whenever desired, the manager obtains the value of the event counter and adjusts its understanding of the history of events at the agent.

• The agent allocates events to 'buckets' where each bucket represents an interval of time.

Telecommunications equipment often makes use of the latter strategy. For such equipment the standard practice is that history data is maintained by the agent in terms of 15-minute intervals [T1.231].

MIB modules for collecting performance history based on 15-minute intervals have been defined for the DS1/E1 [RFC2495], DS3/E3 [RFC2496], SONET/SDH [RFC3592], ADSL [RFC2662], HDLS2 and SHDSL [RFC3276] interface types. These MIB modules use a common set of textual conventions defined in [RFC3593].

A need has arisen to define 64-bit versions of the textual conventions in [RFC3593]. Ideally, these high-capacity textual conventions would be based on a Gauge64 or Unsigned64 data type, but unfortunately no such types exist in SMIv2. The next best choice would be to base them on the CounterBasedGauge64 textual convention presented in [RFC2856], but that is not possible either since SMIv2 allows only base types to be used in defining textual conventions. Therefore, the textual conventions presented in this memo are based directly on the Counter64 type, like those in [RFC2856]. They are subject to the following limitations:

• The MAX-ACCESS of objects defined using these textual conventions must be read-only, because the MAX-ACCESS of the underlying Counter64 type is read-only.

• No sub-range can be specified in object definitions using these textual conventions, because sub-ranges are not allowed on Counter64 objects.

• No DEFVAL clause can be specified in object definitions using these textual conventions, because DEFVALs are not allowed on Counter64 objects.

• Objects defined using these textual conventions cannot be used in an INDEX clause, because there is no INDEX clause mapping defined for objects of type Counter64.

Use of the textual conventions presented in this memo assumes the following:

• The agent supports 15 minute based history counters.

• The agent is capable of keeping a history of 96 intervals of 15 minute performance data.

• The agent may optionally support performance data aggregating the history intervals.

• The agent will keep separate tables for the current interval, the history intervals, and the total aggregates.

3. Definitions

   HC-PerfHist-TC-MIB DEFINITIONS ::= BEGIN

IMPORTS

       MODULE-IDENTITY,
       Counter64,
       Unsigned32,
       Integer32,
       mib-2                FROM SNMPv2-SMI
       TEXTUAL-CONVENTION   FROM SNMPv2-TC;

hcPerfHistTCMIB MODULE-IDENTITY

      LAST-UPDATED "200402030000Z" -- February 3, 2004
      ORGANIZATION "ADSLMIB Working Group"
      CONTACT-INFO "WG-email:  adslmib@ietf.org
      
           Info:      https://www1.ietf.org/mailman/listinfo/adslmib
      
           Chair:     Mike Sneed
                      Sand Channel Systems
           Postal:    P.O.  Box 37324
                      Raleigh NC 27627-7324
                      USA
           Email:     sneedmike@hotmail.com
           Phone:     +1 206 600 7022
      
           Co-editor: Bob Ray
                      PESA Switching Systems, Inc.
           Postal:    330-A Wynn Drive
                      Huntsville, AL 35805
                      USA
           Email:     rray@pesa.com
           Phone:     +1 256 726 9200 ext.  142
      
           Co-editor: Rajesh Abbi
                      Alcatel USA
           Postal:    2301 Sugar Bush Road
                      Raleigh, NC 27612-3339
                      USA
           Email:     Rajesh.Abbi@alcatel.com
           Phone:     +1 919 850 6194
           "
       DESCRIPTION
           "This MIB Module provides Textual Conventions to be
            used by systems supporting 15 minute based performance
            history counts that require high-capacity counts.

Copyright © The Internet Society (2004). This version of this MIB module is part of RFC 3705: see the RFC itself for full legal notices."

REVISION "200402030000Z" -- February 3, 2004

DESCRIPTION "Initial version, published as RFC 3705."

           ::= { mib-2 107 }

HCPerfValidIntervals ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION
          "The number of near end intervals for which data was
       
          collected.  The value of an object with an
          HCPerfValidIntervals syntax will be 96 unless the
          measurement was (re-)started within the last 1440 minutes,
          in which case the value will be the number of complete 15
          minute intervals for which the agent has at least some data.
          In certain cases (e.g., in the case where the agent is a
          proxy) it is possible that some intervals are unavailable.
          In this case, this interval is the maximum interval number
          for which data is available."
       SYNTAX   Integer32 (0..96)

HCPerfInvalidIntervals ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION
          "The number of near end intervals for which no data is
          available.  The value of an object with an
          HCPerfInvalidIntervals syntax will typically be zero except
          in cases where the data for some intervals are not available
          (e.g., in proxy situations)."
       SYNTAX   Integer32 (0..96)

HCPerfTimeElapsed ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION
          "The number of seconds that have elapsed since the beginning
          of the current measurement period.  If, for some reason,
          such as an adjustment in the system's time-of-day clock or
          the addition of a leap second, the duration of the current
          interval exceeds the maximum value, the agent will return
          the maximum value.
       
          For 15 minute intervals, the range is limited to (0..899).
          For 24 hour intervals, the range is limited to (0..86399)."
       SYNTAX   Integer32 (0..86399)

HCPerfIntervalThreshold ::= TEXTUAL-CONVENTION

       STATUS   current
       DESCRIPTION
           "This convention defines a range of values that may be set
           in a fault threshold alarm control.  As the number of
           seconds in a 15-minute interval numbers at most 900,
           objects of this type may have a range of 0...900, where the
           value of 0 disables the alarm."
       SYNTAX   Unsigned32 (0..900)

HCPerfCurrentCount ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION

"A gauge associated with a performance measurement in a

current 15 minute measurement interval. The value of an object with an HCPerfCurrentCount syntax starts from zero and is increased when associated events occur, until the end of the 15 minute interval. At that time the value of the gauge is stored in the first 15 minute history interval, and the gauge is restarted at zero. In the case where the agent has no valid data available for the current interval, the corresponding object instance is not available and upon a retrieval request a corresponding error message shall be returned to indicate that this instance does not exist.

This count represents a non-negative integer, which may increase or decrease, but shall never exceed 2^64-1 (18446744073709551615 decimal), nor fall below 0. The value of an object with HCPerfCurrentCount syntax assumes its maximum value whenever the underlying count exceeds 2^64-1. If the underlying count subsequently decreases below 2^64-1 (due, e.g., to a retroactive adjustment as a result of entering or exiting unavailable time), then the object's value also decreases.

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

HCPerfIntervalCount ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION
           "A gauge associated with a performance measurement in
            a previous 15 minute measurement interval.  In the case
            where the agent has no valid data available for a
            particular interval, the corresponding object instance is
            not available and upon a retrieval request a corresponding
            error message shall be returned to indicate that this
            instance does not exist.

Let X be an object with HCPerfIntervalCount syntax.

Let Y be an object with HCPerfCurrentCount syntax. Let Z be an object with HCPerfTotalCount syntax. Then, in a system supporting a history of n intervals with X(1) and X(n) the most and least recent intervals respectively, the following applies at the end of a 15 minute interval:

               - discard the value of X(n)
               - the value of X(i) becomes that of X(i-1)
                 for n >= i > 1
               - the value of X(1) becomes that of Y.
               - the value of Z, if supported, is adjusted.

This count represents a non-negative integer, which may increase or decrease, but shall never exceed 2^64-1 (18446744073709551615 decimal), nor fall below 0. The value of an object with HCPerfIntervalCount syntax assumes its maximum value whenever the underlying count exceeds 2^64-1. If the underlying count subsequently decreases below 2^64-1 (due, e.g., to a retroactive adjustment as a result of entering or exiting unavailable time), then the value of the object also decreases.

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

HCPerfTotalCount ::= TEXTUAL-CONVENTION

       STATUS  current
       DESCRIPTION
           "A gauge representing the aggregate of previous valid 15
            minute measurement intervals.  Intervals for which no
            valid data was available are not counted.

This count represents a non-negative integer, which may increase or decrease, but shall never exceed 2^64-1 (18446744073709551615 decimal), nor fall below 0. The value of an object with HCPerfTotalCount syntax assumes its maximum value whenever the underlying count exceeds 2^64-1. If the underlying count subsequently decreases below 2^64-1 (due, e.g., to a retroactive adjustment as a result of entering or exiting unavailable time), then the object's value also decreases.

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
   END

4. Intellectual Property Statement

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.

5. References

5.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [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.
   
   [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.

5.2. Informative References

   [RFC3410] Case, J., Mundy, R., Partain, D. and B. Stewart,
             "Introduction and Applicability Statements for Internet-
             Standard Management Framework", RFC 3410, December 2002.
   
   [T1.231]  American National Standard for Telecommunications - Digital
             Hierarchy - Layer 1 In-Service Digital Transmission
             Performance Monitoring, ANSI T1.231-1997, September 1997.
   
   [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
             3", BCP 9, RFC 2026, October 1996.
   
   [RFC2495] Fowler, D., "Definitions of Managed Objects for the DS1,
             E1, DS2 and E2 Interface Types", RFC 2495, January 1999.
   
   [RFC2496] Fowler, D., "Definitions of Managed Objects for the DS3/E3
             Interface Type", RFC 2496, January 1999.
   
   [RFC3592] Tesink, K., "Definitions of Managed Objects for the
             Synchronous Optical Network/Synchronous Digital Hierarchy
             (SONET/SDH) Interface Type", RFC 3592, November 2003.
   
   [RFC2662] Bathrick, G. and F. Ly, "Definitions of Managed Objects for
             the ADSL Lines",  RFC 2662, August 1999.
   
   [RFC2856] Bierman, A., McCloghrie, K.  and R. Presuhn, "Textual
             Conventions for Additional High Capacity Data Types", RFC
             2856, June 2000.
   
   [RFC3276] Ray, B. and R. Abbi, "Definitions of Managed Objects for
             High Bit-rate DSL - 2nd Generation (HDSL2) and Single-Pair
             High-Speed Digital Subscriber Line (SHDSL) Lines", RFC
             3276, May 2002.
   
   [RFC3593] Tesink, K., "Textual Conventions for MIB Modules Using
             Performance History Based on 15 Minute Intervals", RFC
             3593,  November 2003.

6. 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 MIB modules that define management objects. This document has therefore no impact on the security of the Internet.

7. Acknowledgements

This document borrows tremendously from [RFC3593] and [RFC2856]. As such, any credit for the text found within should be fully attributed to the authors of those documents.

8. Authors' Addresses

Bob Ray
PESA Switching Systems, Inc.
330-A Wynn Drive
Huntsville, AL 35805
USA

   Phone: +1 256 726 9200 ext. 142
   Fax:   +1 256 726 9271
   EMail: rray@pesa.com

Rajesh Abbi
Alcatel USA
2301 Sugar Bush Road
Raleigh, NC 27612-3339
USA

   Phone: +1 919 850 6194
   EMail: Rajesh.Abbi@alcatel.com

9. Full Copyright Statement

Copyright © The Internet Society (2004). 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 assignees.

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.