wdiff draft-ietf-atommib-rfc2493bis-00.txt draft-ietf-atommib-rfc2493bis-01.txt

draft 15 Minute Based Performance History TCs 2/18/2002A new Request for Comments is now available in online RFC libraries.

RFC 3593

Title: Textual Conventions for MIB Modules Using
Performance History Based on 15 Minute Intervals

February 18, 2002

Kaj Tesink
Telcordia Technologies
Author(s): K. Tesink, Ed.
Status: Standards Track
Date: September 2003
Mailbox: kaj@research.telcordia.com

<draft-ietf-atommib-rfc2493bis-00.txt>

1. Status of this Memo

This document is an Internet-Draft and is in full conformance
with all provisions of Section
Pages: 10 of RFC2026. Internet-Drafts
are working documents of the Internet Engineering Task Force
(IETF), its areas, and its working groups. Note that other
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Abstract
Characters: 20363
Obsoletes: 2493

I-D Tag: draft-ietf-atommib-rfc2493bis-01.txt

URL: ftp://ftp.rfc-editor.org/in-notes/rfc3593.txt

This document defines a set of Textual Conventions for MIB
modules which that make use of performance history data based on 15
minute intervals.

draft 15 Minute Based Performance History TCs 2/18/2002

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:

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 replaces RFC 2493. Changes 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 RFC 2579 [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].

draft 15 Minute Based Performance History TCs 2/18/2002

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 2493 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.

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
draft 15 Minute Based Performance History TCs 2/18/2002
summarized 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]).

draft 15 Minute Based Performance History TCs 2/18/2002

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 "200202180742Z"
ORGANIZATION "IETF AToMMIB WG"
CONTACT-INFO "AToMMIB WG:
http://www.ietf.org/html.charters/atommib-charter.html

Kaj Tesink
Postal: Telcordia Technologies
331 Newman Springs Road
Red Bank, NJ 07701
USA
Tel: +1 732 758 5254
E-mail: kaj@research.telcordia.com"
DESCRIPTION
"This MIB Module provides Textual Conventions
to be used by systems supporting 15 minute
based performance history counts."
REVISION "200202180742Z"
DESCRIPTION
"Contact information and references updated.
No technical changes have been applied." module's REVISION "9811071100Z"
DESCRIPTION
"The RFC2493 version of this MIB module."
::= { mib-2 58 }

-- The Textual Conventions defined below are organized
-- alphabetically

draft 15 Minute Based Performance History TCs 2/18/2002

-- Use of these TCs assumes the following:
-- 0 The agent supports 15 minute based history
-- counters.
-- 0 The agent clause.

This document is capable of keeping a history of n
-- intervals of 15 minute performance data. The
-- value product of n is defined by the specific AToM 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
-- "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 Working Group of complete 15

draft 15 Minute Based Performance History TCs 2/18/2002

-- minute intervals for which the agent has at least
-- some data. In certain cases (e.g., in the case
-- where the agent IETF.

This is now 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. Draft Standard Protocol.

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 document specifies an Internet standards track protocol for
the current interval the
corresponding object instance is not
available Internet community, 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 requests discussion and a noSuchInstance suggestions
for
SNMPv2 GET operation)."
SYNTAX Gauge32

draft 15 Minute Based Performance History TCs 2/18/2002

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 improvements. Please refer 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

draft 15 Minute Based Performance History TCs 2/18/2002

7. Acknowledgments

This document is a product edition of the AToMMIB Working Group.

draft 15 Minute Based Performance History TCs 2/18/2002

8. References

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

[2] 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.

[3] Nicklass, O., "Definitions of Managed Objects
"Internet Official Protocol Standards" (STD 1) for the
DS1, E1, DS2
standardization state and E2 Interface Types", <draft-ietf-
atommib-rfc2495bis-00.txt>, work in progress.

[4] Nicklass, O., "Definitions of Managed Objects for the
DS3/E3 Interface Type", <draft-ietf-atommib-rfc2496bis-
00.txt>, work in progress.

[5] Tesink, K., "Definitions of Managed Objects for the
SONET/SDH Interface Type", <draft-ietf-atommib-
rfc2558bis-00.txt>, 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.

draft 15 Minute Based Performance History TCs 2/18/2002

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. Author's Address

Kaj Tesink
Telcordia Technologies
331 Newman Springs Road
P.O. Box 7020
Red Bank, NJ 07701-7020
Phone: +1 732 758 5254
E-mail: kaj@research.telcordia.com

draft 15 Minute Based Performance History TCs 2/18/2002

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draft 15 Minute Based Performance History TCs 2/18/2002

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draft 15 Minute Based Performance History TCs 2/18/2002

Table of Contents

1 Status of this Memo ................................... 1
2 Introduction .......................................... 2
3 Note on Invalid Data and Proxy ........................ 3
4 Note on xyzTimeElapsed ................................ 3
5 Note on xyzValidIntervals ............................. 4
6 Definitions ........................................... 5
7 Acknowledgments ....................................... 9
8 References ............................................ 10
9 Security Considerations ............................... 11
10 Author's Address ..................................... 11
11 Intellectual Property ................................ 12
12 Full Copyright Statement ............................. 13 sent to
RFC-EDITOR@RFC-EDITOR.ORG. Please consult RFC 2223, Instructions to RFC
Authors, for further information.