Textual Conventions for MIB Modules Using Performance History Based on 15 Minute Intervals
RFC 2493

Document Type RFC - Proposed Standard (January 1999; No errata)
Obsoleted by RFC 3593
Last updated 2013-03-02
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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
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