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diff --git a/doc/rfc/rfc2493.txt b/doc/rfc/rfc2493.txt new file mode 100644 index 0000000..a631ebc --- /dev/null +++ b/doc/rfc/rfc2493.txt @@ -0,0 +1,507 @@ + + + + + + +Network Working Group K. Tesink, Editor +Request for Comments: 2493 Bellcore +Category: Standards Track January 1999 + + + 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 (C) The Internet Society (1999). 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. + +1. Table of Contents + + 1 Table of Contents ..................................... 1 + 2 Introduction .......................................... 1 + 3 Note on Invalid Data and Proxy ........................ 2 + 4 Note on xyzTimeElapsed ................................ 3 + 5 Note on xyzValidIntervals ............................. 3 + 6 Definitions ........................................... 3 + 7 Acknowledgments ....................................... 7 + 8 References ............................................ 7 + 9 Security Considerations ............................... 8 + 10 IANA Considerations .................................. 8 + 11 Author's Address ..................................... 8 + 12 Intellectual Property ................................ 8 + 13 Full Copyright Statement ............................. 9 + +2. Introduction + + 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 that represents the managed + equipment, including: + + + +Tesink, Ed. Standards Track [Page 1] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + + 0 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. + + 0 The agent allocates events to 'buckets' where each bucket + represents an interval of time. + + Telecommunications equipment often makes use of the latter strategy. + See [3][4][5] for examples. In particular, for this equipment it is + common that history data is maintained by the agent in terms of + fifteen minute intervals. + + This memo does not attempt to compare the relative merits of + different strategies to obtain history data. Differences may include + polling policy, the amount of management traffic between manager and + agent, agent simplicity, and 'data currentness' of the data obtained + by the manager. MIB designers should consider these aspects when + choosing a particular strategy in a MIB design. Instead, this memo + provides definitions that can be used in MIB modules that require + history data based on fifteen minute intervals. + + 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. + + + + +Tesink, Ed. Standards Track [Page 2] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + +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. + + 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]). + +6. Definitions + + PerfHist-TC-MIB DEFINITIONS ::= BEGIN + + IMPORTS + MODULE-IDENTITY, + Gauge32, mib-2 + FROM SNMPv2-SMI + TEXTUAL-CONVENTION + FROM SNMPv2-TC; + + + perfHistTCMIB MODULE-IDENTITY + + + +Tesink, Ed. Standards Track [Page 3] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + + LAST-UPDATED "9811071100Z" + 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@bellcore.com" + DESCRIPTION + "This MIB Module provides Textual Conventions + to be used by systems supporting 15 minute + based performance history counts." + ::= { mib-2 58 } + + + + + -- 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. + -- 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 + + + +Tesink, Ed. Standards Track [Page 4] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + + -- "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 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 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." + -- ::= { xxx } + + -- xyzInvalidIntervals OBJECT-TYPE + -- 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 + + + +Tesink, Ed. Standards Track [Page 5] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + + 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 + 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 + + + +Tesink, Ed. Standards Track [Page 6] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + + 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 + +7. Acknowledgments + + This document is a product of the AToMMIB and TrunkMIB Working + Groups. + +8. References + + [1] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, + "Textual Conventions for Version 2 of the Simple Network + Management Protocol (SNMPv2)", RFC 1903, 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)", RFC 1902, January 1996. + + [3] Fowler, D., "Definitions of Managed Objects for the DS1, E1, DS2 + and E2 Interface Types", RFC 2495, January 1999. + + [4] Fowler, D., "Definitions of Managed Objects for the DS3/E3 + Interface Type", RFC 2496, January 1999. + + [5] Tesink, K., "Definitions of Managed Objects for the SONET/SDH + Interface Type", Work in Progress. + + [6] American National Standard for Telecommunications - Digital + Hierarchy - Layer 1 In-Service Digital Transmission Performance + Monitoring, ANSI T1.231-1997, September 1997. + + + + + + + + + + + + + +Tesink, Ed. Standards Track [Page 7] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + +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. + +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@bellcore.com + +12. 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. + + + + + + + + +Tesink, Ed. Standards Track [Page 8] + +RFC 2493 15 Minute Based Performance History TCs January 1999 + + +13. Full Copyright Statement + + Copyright (C) The Internet Society (1999). 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. + + + + + + + + + + + + + + + + + + + + + + + + +Tesink, Ed. 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