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Versions: 00 01 02 03 04 05 rfc2493                                     
          Textual Conventions for MIB Modules Using Performance History
                           Based on 15 Minute Intervals
          
                                September 1, 1998
          
          
          
                               Kaj Tesink  (editor)
                                     Bellcore
                               kaj@cc.bellcore.com
          
          
          
          
          
          1.  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 ftp.ietf.org (US East
          Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast),
          or munnari.oz.au (Pacific Rim).
          
          Copyright Notice
          
          Copyright (C) The Internet Society (1998).  All Rights
          Reserved.
          
          Abstract
          
          This document defines a set of Textual Conventions for MIB
          modules which make use of performance history data based on 15
          minute intervals.
          
          
          
          
          
          
          
          
          
          
          
          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          2.  Introduction
          
          When designing a MIB module, it is often useful to define new
          types similar to those defined in the SMI [2].  In comparison
          to a type defined in the SMI, each of these new types has a
          different name, a similar syntax, but a more precise
          semantics.  These newly defined types are termed textual
          conventions, and are used for the convenience of humans
          reading the MIB module.  This is done through Textual
          Conventions as defined in RFC1903[1].  It is the purpose of
          this document to define the set of textual conventions to be
          used when performance history based on 15 minute intervals is
          kept. See for example the Trunk MIB modules [3][4][5].
          
          
          3.  Note on Invalid Data and Proxy
          
          In this document, the word proxy is meant to indicate an
          application which receives SNMP messages and replies to them
          on behalf of the devices where the actual implementation
          resides, e.g., DS3/E3 interfaces.  The proxy will have already
          collected the information about the DS3/E3 interfaces into its
          local database and may not necessarily forward requests to the
          actual DS3/E3 interface.  It is expected in such an
          application that there are periods of time where the proxy is
          not communicating with the DS3/E3 interfaces. In these
          instances the proxy will not necessarily have up-to-date
          configuration information and will most likely have missed the
          collection of some data. Missed data collection may result in
          some intervals in the interval table being unavailable.
          
          
          4.  Note on xyzTimeElapsed
          
          While xyzTimeElapsed is defined as having a maximum there may
          be cases (e.g., an adjustment in the system's time-of-day
          clock) where the actual value of the current interval would
          exceed this maximum value.
          
          Suppose that an agent which aligns its 15-minute measurement
          intervals to 15-minute time-of-day ("wall clock") boundaries
          has a time-of-day clock that systematically gains time, and
          that a manager periodically corrects the clock by setting it
          back.
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          It is assumed that the agent's time-of-day clock is reasonably
          accurate, say within a few seconds per day. Thus, the
          manager's periodic clock adjustments will normally be small,
          and if done frequently enough, need not ever exceed 10
          seconds.  In this case all interval durations will be within
          the allowed tolerance and none need be marked invalid, _if_
          the ANSI procedure of ending measurement intervals at 15-
          minute time-of-day boundaries is followed [6].
          
          If the time-of-day clock is systematically adjusted in small
          increments, then always ending measurement intervals at 15-
          minute time-of-day boundaries will result in the long term in
          the correct number of intervals with the correct average
          duration, irrespective of whether the clock is moved ahead or
          moved back.  Thus, if, for some reason, such as an adjustment
          in the system's time-of-day clock, the current interval
          exceeds the maximum value, it is considered acceptable that
          the agent will return the maximum value.
          
          
          5.  Note on xyzValidIntervals
          
          The overall constraint on <n> is 1 =< n =< 96.  Any additional
          constraints on n must be defined in the DESCRIPTION clause
          (e.g., see [5]).
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          6.  Definitions
          
               PerfHist-TC-MIB DEFINITIONS ::= BEGIN
          
               IMPORTS
                  MODULE-IDENTITY,
                  Gauge32, mib-2
                      FROM SNMPv2-SMI
                  TEXTUAL-CONVENTION
                      FROM SNMPv2-TC;
          
          
               perfHistTCMIB MODULE-IDENTITY
                    LAST-UPDATED "9809011100Z"
                    ORGANIZATION "IETF AToMMIB and TrunkMIB WGs"
                    CONTACT-INFO
                                 "Kaj Tesink
                        Postal:  Bellcore
                                 331 Newman Springs Road
                                 Red Bank, NJ 07701
                                 USA
                        Tel:     +1 732 758 5254
                        Fax:     +1 732 758 2269
                        E-mail:  kaj@cc.bellcore.com"
                    DESCRIPTION
                     "This MIB Module provides Textual Conventions
                       to be used by systems supporting 15 minute
                       based performance history counts."
                    ::= { mib-2 xxx }    -- to be filled in by IANA
          
          
          
          
               -- The Textual Conventions defined below are organized
               -- alphabetically
          
               -- Use of these TCs assumes the following:
               -- 0  The agent supports 15 minute based history
               --    counters.
               -- 0  The agent is capable of keeping a history of n
               --    intervals of 15 minute performance data. The
               --    value of n is defined by the specific MIB
               --    module but shall be 0 < n =< 96.
               -- 0  The agent may optionally support performance
               --    data aggregating the history intervals.
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
               -- 0  The agent will keep separate tables for the
               --    current interval, the history intervals, and
               --    the total aggregates.
               -- 0  The agent will keep the following objects.
               --    If performance data is kept for multiple instances
               --    of a measured entity, then
               --    these objects are applied to each instance of
               --    the measured entity (e.g., interfaces).
               --
          
          
               -- xyzTimeElapsed OBJECT-TYPE
               --       SYNTAX  INTEGER (0..899)
               --       MAX-ACCESS  read-only
               --       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, the current interval
               --       exceeds the maximum value, the agent will return
               --       the maximum value."
               --       ::= { xxx }
          
               -- xyzValidIntervals OBJECT-TYPE
               --       SYNTAX  INTEGER (0..<n>)
               --       MAX-ACCESS  read-only
               --       STATUS  current
               --       DESCRIPTION
               --       "The number of previous near end intervals
               --       for which valid data was collected.
               --          [ The overall constraint on <n> is 1 =< n =< 96; ]
               --          [ Define any additional constraints on <n> here. ]
               --       The value will be <n> unless the measurement was
               --       (re-)started within the last (<n>*15) minutes, in which
               --       case the value will be the number of complete 15
               --       minute intervals for which the agent has at least
               --       some valid 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 valid data is available."
               --       ::= { xxx }
          
               -- xyzInvalidIntervals OBJECT-TYPE
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
               --     SYNTAX  INTEGER (0..<n>)
               --     MAX-ACCESS  read-only
               --     STATUS  current
               --     DESCRIPTION
               --       "The number of intervals in the range from
               --        0 to xyzValidIntervals for which no
               --        data is available. This object will typically
               --        be zero except in cases where the data for some
               --        intervals are not available (e.g., in proxy
               --        situations)."
               --       ::= { xxx }
          
               PerfCurrentCount ::= TEXTUAL-CONVENTION
                     STATUS  current
                     DESCRIPTION
                        "A counter associated with a
                         performance measurement in a current 15
                         minute measurement interval. The value
                         of this counter 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 counter is
                         stored in the first 15 minute history
                         interval, and the CurrentCount 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 (for example, a noSuchName
                         error for SNMPv1 and a noSuchInstance for
                         SNMPv2 GET operation)."
                      SYNTAX  Gauge32
          
               PerfIntervalCount ::= TEXTUAL-CONVENTION
                     STATUS  current
                     DESCRIPTION
                        "A counter 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
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
                         available and upon a retrieval request
                         a corresponding error message shall be
                         returned to indicate that this instance
                         does not exist (for example, a noSuchName
                         error for SNMPv1 and a noSuchInstance for
                         SNMPv2 GET operation).
                         In a system supporting
                         a history of n intervals with
                         IntervalCount(1) and IntervalCount(n) the
                         most and least recent intervals
                         respectively, the following applies at
                         the end of a 15 minute interval:
                         - discard the value of IntervalCount(n)
                         - the value of IntervalCount(i) becomes that
                           of IntervalCount(i-1) for n >= i > 1
                         - the value of IntervalCount(1) becomes that
                           of CurrentCount
                         - the TotalCount, if supported, is adjusted."
                      SYNTAX  Gauge32
          
               PerfTotalCount ::= TEXTUAL-CONVENTION
                     STATUS  current
                     DESCRIPTION
                        "A counter associated with a
                         performance measurements aggregating the
                         previous valid 15 minute measurement
                         intervals. (Intervals for which no valid
                         data was available are not counted)"
                      SYNTAX  Gauge32
          
          
               END
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          7.  Acknowledgments
          
          This document is a product of the AToMMIB and TrunkMIB Working
          Groups.
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          8.  References
          
          [1]  Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
               "Textual Conventions for Version 2 of the Simple Network
               Management Protocol (SNMPv2)", RFC1903, SNMP
               Research,Inc., Cisco Systems, Inc., Dover Beach
               Consulting, Inc., International Network Services, January
               1996.
          
          [2]  Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
               "Structure of Management Information for Version 2 of the
               Simple Network Management Protocol (SNMPv2)", RFC1902,
               SNMP Research,Inc., Cisco Systems, Inc., Dover Beach
               Consulting, Inc., International Network Services, January
               1996.
          
          [3]  Fowler, D., "Definitions of Managed Objects for the DS1,
               E1, DS2 and E2 Interface Types", RFCxxxx, Newbridge
               Networks, ????? 1998.
          
          [4]  Fowler, D., "Definitions of Managed Objects for the
               DS3/E3 Interface Type", RFCxxxx, Newbridge Networks, ????
               1998.
          
          [5]  Tesink, K., "Definitions of Managed Objects for the
               SONET/SDH Interface Type", RFCxxxx, Bellcore, ???? 1998.
          
          [6]  American National Standard for Telecommunications -
               Digital Hierarchy - Layer 1 In-Service Digital
               Transmission Performance Monitoring, ANSI T1.231-1997,
               September 1997.
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          9.  Security Considerations
          
          This memo defines textual conventions for use in other MIB
          modules. Security issues for these MIB modules are addressed
          in the memos defining those modules.
          
          
          10.  IANA Considerations
          
          Prior to publication of this memo as an RFC, IANA is requested
          to make a suitable OBJECT IDENTIFIER assignment and update the
          following line in the MIB:
          
               ::= { mib-2 xxx }    -- to be filled in by IANA
          
          11.  Author's Address
          
                            Kaj Tesink
                            Bellcore
                            331 Newman Springs Road
                            P.O. Box 7020
                            Red Bank, NJ  07701-7020
                            Phone: (732) 758-5254
                            EMail: kaj@cc.bellcore.com
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          12.  Full Copyright Statement
          
          Copyright (C) The Internet Society (1998).  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."
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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          draft      15 Minute Based Performance History TCs    9/1/1998
          
          
          Table of Contents
          
          
          1 Status of this Memo ...................................    1
          2 Introduction ..........................................    2
          3 Note on Invalid Data and Proxy ........................    2
          4 Note on xyzTimeElapsed ................................    2
          5 Note on xyzValidIntervals .............................    3
          6 Definitions ...........................................    4
          7 Acknowledgments .......................................    8
          8 References ............................................    9
          9 Security Considerations ...............................   10
          10 IANA Considerations ..................................   10
          11 Author's Address .....................................   10
          12 Full Copyright Statement .............................   11
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
          
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