PMP Mail Archive: PMP> [Fwd: Expression MIB]

PMP Mail Archive: PMP> [Fwd: Expression MIB]

PMP> [Fwd: Expression MIB]

Randy Turner (rturner@sharplabs.com)
Fri, 04 Apr 1997 14:29:52 -0800

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-- 
Randy Turner
Network Architect
Sharp Laboratories of America
rturner@sharplabs.com

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Received: from slafw.sharplabs.com (gatekeeper.sharplabs.com [204.203.96.101]) by sla5c.enet.sharplabs.com (8.8.4/8.8.4) with ESMTP id FAA00847 for <rturner@sheltie.sharplabs.com>; Wed, 2 Apr 1997 05:28:32 -0800 (PST) Received: from guelah.nexen.com (guelah.nexen.com [204.249.96.19]) by slafw.sharplabs.com (8.8.4/8.7.3) with ESMTP id FAA05806 for <rturner@sharplabs.com>; Wed, 2 Apr 1997 05:34:48 -0800 (PST) Received: from maelstrom.nexen.com (maelstrom.nexen.com [204.249.99.5]) by guelah.nexen.com (8.8.5/8.7.3) with ESMTP id IAA16087; Wed, 2 Apr 1997 08:18:15 -0500 (EST) Received: (from root@localhost) by maelstrom.nexen.com (8.8.5/8.7.3) id IAA08886 for disman-out; Wed, 2 Apr 1997 08:17:25 -0500 (EST) Received: from nexen.nexen.com (nexen.nexen.com [204.249.96.18]) by maelstrom.nexen.com (8.8.5/8.7.3) with ESMTP id IAA08875 for <disman@nexen.com>; Wed, 2 Apr 1997 08:17:18 -0500 (EST) Received: from puli.cisco.com (puli.cisco.com [171.69.1.174]) by nexen.nexen.com (8.8.5/8.7.3) with SMTP id IAA01699 for <disman@nexen.com>; Wed, 2 Apr 1997 08:17:51 -0500 (EST) Received: from [171.69.128.42] (gryphon.cisco.com [171.69.128.42]) by puli.cisco.com (8.6.12/8.6.5) with ESMTP id FAA20285 for <disman@nexen.com>; Wed, 2 Apr 1997 05:17:46 -0800 X-Sender: bstewart@puli.cisco.com Message-Id: <v0310250baf680c8c5da6@[171.69.128.42]> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 2 Apr 1997 08:16:42 -0500 To: Distributed Management WG <disman@nexen.com> From: Bob Stewart <bstewart@cisco.com> Subject: Expression MIB Sender: owner-disman@nexen.com Precedence: bulk X-Info: [Un]Subscribe to disman-request@nexen.com, submissions to disman@nexen.com

Internet Draft Expression MIB 26 March 1997

Expression MIB

26 March 1997

draft-ietf-disman-express-mib-00.txt

Bob Stewart Cisco Systems, Inc. bstewart@cisco.com

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 ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).

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1. Abstract

This memo defines an experimental portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes managed objects used for managing expressions of MIB objects.

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2. The SNMP Network Management Framework

They are: The SNMP Network Management Framework presently consists of three major components. They are:

the SMI, described in RFC 1902 [1] - the mechanisms used for describing and naming objects for the purpose of management.

the MIB-II, STD 17, RFC 1213 [2] - the core set of managed objects for the Internet suite of protocols.

the protocol, RFC 1157 [3] and/or RFC 1905 [4], - the protocol for accessing managed objects.

The Framework permits new objects to be defined for the purpose of experimentation and evaluation.

2.1. Object Definitions

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) defined in the SMI. In particular, each object type is named by an OBJECT IDENTIFIER, an administratively assigned name. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the descriptor, to refer to the object type.

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3. Overview

The MIB was designed around the basic premise that an evaluated expression should result in a MIB object that appears no different from any other and is thus usable anywhere any other MIB object can be used, whether by a management application directly or via another MIB.

Note that the operation of this MIB depends on the ability to use OID fragments, that is, a part of an OID that may be missing the usual prefix starting with iso. It is the opinion of the author that such a use is legitimate even if it violates some pure definition of ASN.1, since SNMP's use of ASN.1 is colloquial, not standard. The more important test is whether implementations can readily handle such OID fragments, and I believe they should be able to.

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4. Definitions

EXPRESSION-MIB DEFINITIONS ::= BEGIN

IMPORTS MODULE-IDENTITY, OBJECT-TYPE, experimental, Integer32, Unsigned32 FROM SNMPv2-SMI TEXTUAL-CONVENTION, RowStatus, AutonomousType, DisplayString, FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF

expressionMIB MODULE-IDENTITY LAST-UPDATED "9703141700Z" ORGANIZATION "IETF Distributed Management Working Group" CONTACT-INFO "Bob Stewart Cisco Systems, Inc. 170 West Tasman Drive, San Jose CA 95134-1706. Phone: +1 408 526 4527 Email: bstewart@cisco.com" DESCRIPTION "The MIB module for defining expressions of MIB objects for network management purposes." ::= { experimental xx }

ExpressionName ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An identification for an expression. An ExpressionName corresponds one-to-one to an ExpressionIndex.

This is the reliable identification of an expression, subject to change only by administrative request." SYNTAX DisplayString (SIZE (1..64))

ExpressionIndex ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "An integer shorthand identification for an expression. An ExpressionIndex corresponds one-to-one to an ExpressionName.

A system may change the value of an ExpressionIndex when it is reinitialized but must correct all references to that ExpressionIndex."

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SYNTAX Unsigned32 (1..4294967295)

ExpressionIndexOrZero ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "Either an ExpressionIndex or zero. The meaning of zero depends on the DESCRIPTION of the object." SYNTAX Unsigned32 (0..4294967295)

expressionMIBObjects OBJECT IDENTIFIER ::= { expressionMIB 1 }

expCreate OBJECT IDENTIFIER ::= { expressionMIBObjects 1 } expDefine OBJECT IDENTIFIER ::= { expressionMIBObjects 2 } expValue OBJECT IDENTIFIER ::= { expressionMIBObjects 3 }

--
-- Creation Table
--

expCreateLastChange OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime the last time an expression was created or deleted or had its name changed using expExpressionName." ::= { expCreate 1 }

expCreateTable OBJECT-TYPE SYNTAX SEQUENCE OF ExpCreateEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of expression names, for creating and deleting expressions." ::= { expCreate 2 }

expCreateEntry OBJECT-TYPE SYNTAX ExpCreateEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information about a single expression. New expressions

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can be created using expCreateStatus.

To create an expression create the named entry in this table and activate it with RowStatus. Then use expExpressionIndex to populate expExpressionTable expObjectTable.

Deleting an entry deletes all related entries in expExpressionTable and expObjectTable." INDEX { IMPLIED expExpressionName } ::= { expCreateTable 1 }

ExpCreateEntry ::= SEQUENCE { expCreateName ExpressionName, expExpressionIndex ExpressionIndex, expCreateStatus RowStatus }

expCreateName OBJECT-TYPE SYNTAX ExpressionName MAX-ACCESS not-accessible STATUS current DESCRIPTION "The name of the expression. Choosing names with useful lexical ordering supports using GetNext or GetBulk to retrieve a useful subset of the table." ::= { expCreateEntry 1 }

expExpressionIndex OBJECT-TYPE SYNTAX ExpressionIndex MAX-ACCESS read-only STATUS current DESCRIPTION "The numeric identification of the expression." ::= { expCreateEntry 2 }

expCreateStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "The control that allows creation/deletion of entries.

Activate the entry then use expExpressionIndex to define the expression in expExpressionTable."

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::= { expCreateEntry 3 }

--
-- Expression Definition Table
--

expExpressionTable OBJECT-TYPE SYNTAX SEQUENCE OF ExpExpressionEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of expression definitions." ::= { expDefine 1 }

expExpressionEntry OBJECT-TYPE SYNTAX ExpExpressionEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information about a single expression. An entry appears in this table when an expCreateEntry is activated. Deleting the matching expCreateEntry deletes this entry and its associated expObjectTable entries." INDEX { expExpressionIndex } ::= { expExpressionTable 1 }

ExpExpressionEntry ::= SEQUENCE { expExpressionName ExpressionName, expExpression DisplayString, expExpressionComment DisplayString, expExpressionPrefix OBJECT IDENIFIER }

expExpressionName OBJECT-TYPE SYNTAX ExpressionName MAX-ACCESS read-write STATUS current DESCRIPTION "The unique name of the expression, the same as expCreateName.

Use this object to change the expression's name without changing its expExpressionIndex." ::= { expExpressionEntry 1 }

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expExpression OBJECT-TYPE SYNTAX DisplayString (SIZE (1..1024)) MAX-ACCESS read-write STATUS current DESCRIPTION "The expression to be evaluated. Except for the variable names the expression is in ANSI C syntax. ANSI C operators and functions are allowed only if explicitly listed here.

Variables are expressed as a dollar sign ('$') and an integer that corresponds to an expObjectIndex. An example of a valid expression is:

($1-$5)*100

The only operators and functions allowed are:

( ) + - * / & | ^ << >> ~ ! && || == != > >= < <=

Integer-typed object are treated as 32- or 64-bit, signed or unsigned integers, as appropriate. The results of mixing them are as for ANSI C.

OCTET STRINGS and OBJECT IDENTIFIERs are treated as arrays of unsigned 8-bit integers and unsigned 32-bit integers, respectively.

A short list of array handling functions for comparing and masking are to be defined.

Conditional expressions result in a 32-bit, unsigned integer of value 0 for false or 1 for true. When an arbitrary value is used in a boolean expression 0 is false and non-zero is true." DEFVAL { ''H } ::= { expExpressionEntry 2 }

expExpressionComment OBJECT-TYPE SYNTAX DisplayString MAX-ACCESS read-write STATUS current DESCRIPTION

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"A comment to explain the use or meaning of the expression." DEFVAL { ''H } ::= { expExpressionEntry 3 }

expExpressionPrefix OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS current DESCRIPTION "An object prefix to assist an application in determining the instance indexing to use in expValueTable, relieving the application of the need to scan the expObjectTable to determine such a prefix.

See expObjectTable for information on wildcarded objects.

If the expValueInstance portion of the value OID may be treated as a scalar (that is, normally, 0) the value of expExpressionPrefix is 0.0.

Otherwise expExpressionPrefix is the value of any wildcarded instance of expObjectID for the expression. This is sufficient as the remainder, that is, the instance fragment relevant to instancing the values must be the same for all wildcarded objects in the expression." ::= { expExpressionEntry 4 }

--
-- Object Table
--

expObjectTable OBJECT-TYPE SYNTAX SEQUENCE OF ExpObjectEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of object definitions for each expExpression.

Wildcarding instance IDs:

It is legal to omit all or part of the instance portion for some or all of the objects in an expression. (See the DESCRIPTION of expObjectID for details. However, note that if more than one object in the same expression is wildcarded

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in this way, they all must be objects where that portion of the instance is the same. In other words, all objects may be in the same SEQUENCE or in different SEQUENCEs but with the same semantic index value (e.g., the value of ifIndex) for the wildcarded portion." ::= { expDefine 2 }

expObjectEntry OBJECT-TYPE SYNTAX ExpObjectEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information about a object. An application creates entries in this table while creating an expression." -- SPARSE-AUGMENTS { expExpressionEntry } INDEX { expExpressionIndex, expObjectIndex } ::= { expObjectTable 1 }

ExpObjectEntry ::= SEQUENCE { expObjectIndex Unsigned32, expObjectID OBJECT IDENTIFIER, expObjectSampleType INTEGER, expObjectDeltaInterval Integer32, expObjectDeltaDiscontinuityID OBJECT IDENTIFIER, expObjectConditional OBJECT IDENTIFIER, expObjectStatus RowStatus }

expObjectIndex OBJECT-TYPE SYNTAX Unsigned32 (1..4294967295) MAX-ACCESS not-accessible STATUS current DESCRIPTION "A unique, numeric identification for an object. Prefixed with a dollar sign ('$') this is used to reference the object in the corresponding expExpression." ::= { expObjectEntry 1 }

expObjectID OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-create STATUS current DESCRIPTION "The OBJECT IDENTIFIER (OID) of this object. Note that this can be the OID of a leaf object in a MIB (e.g., ifInOctets.1

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or sysUpTime.0). The OID may be fully qualified, meaning it includes an instance identifier part, or it may not be fully qualified, meaning it may lack all or part of the instance identifier. If the expObjectID is not fully qualified, then the value of the expression will be multiple values, as if done for a GetNext sweep of the object." ::= { expObjectEntry 2 }

expObjectSampleType OBJECT-TYPE SYNTAX INTEGER { absoluteValue(1), deltaValue(2) } MAX-ACCESS read-create STATUS current DESCRIPTION "The method of sampling the selected variable." DEFVAL { absoluteValue } ::= { expObjectEntry 3 }

expObjectDeltaInterval OBJECT-TYPE SYNTAX Integer32 (0..86400) UNITS "seconds" MAX-ACCESS read-create STATUS current DESCRIPTION "Sampling interval for objects with expObjectSampleType 'deltaValue'.

This object is not instantiated if not applicable.

A value of 0 indicates no automated sampling. In this case the delta is the difference from the last time the expression was evaluated. Note that this is subject to unpredictable delta times in the face of retries or multiple managers.

A value greater than zero is the number of seconds between automated samples.

Until the delta interval has expired once the delta for the object is effectively not instantiated and evaluating the expression has results as if the object itself were not instantiated.

Note that delta values potentially consume large amounts of

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system CPU and memory. Delta state and processing must continue constantly even if the expression is not being used. For wildcarded objects this can be substantial overhead." DEFVAL { 0 } ::= { expObjectEntry 4 }

expObjectDeltaDiscontinuityID OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-create STATUS current DESCRIPTION "The OBJECT IDENTIFIER (OID) of a TimeTicks object that indicates a discontinuity in the value at expObjectID.

This object is not instantiated if not applicable.

The OID may be for a leaf object (e.g. sysUpTime.0) or may be wildcarded to match expObjectID. DEFVAL { 0 0 } ::= { expObjectEntry 5 }

expObjectConditional OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-create STATUS current DESCRIPTION "The OBJECT IDENTIFIER (OID) of an object that overrides whether the instance of expObjectID is to be considered usable. If the value of the object at expObjectConditional is 0, the object at expObjectID is treated as if it is not instantiated, otherwise it is treated as usual.

The OID may be for a leaf object (e.g. sysUpTime.0) or may be wildcarded to match expObjectID. DEFVAL { 0 0 } ::= { expObjectEntry 5 }

expObjectStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "The control that allows creation/deletion of entries." ::= { expObjectEntry 7 }

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--
-- Expression Value Table
--

expValueTable OBJECT-TYPE SYNTAX SEQUENCE OF ExpValueEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of values from evaluated expressions." ::= { expValue 1 }

expValueEntry OBJECT-TYPE SYNTAX ExpValueEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A single value from an evaluated expression. For a given instance, only one "Val" object in the conceptual row will be instantiated, that is, the one with the appropriate type for the value. Reading a value from the table causes the evaluation of the expression for that value.

If in the attempt to evaluate the expression one or more of the necessary objects is not available, the corresponding entry in this table is effectively not instantiated." INDEX { expExpressionIndex, expValueInstance } ::= { expValueTable 1 }

ExpValueEntry ::= SEQUENCE { expValueInstance OBJECT IDENTIFIER, expValueType INTEGER, expValueUnsigned32Val Unsigned32, expValueInteger32Val Integer32, expValueOctetStringVal OCTET STRING, expValueOidVal OBJECT IDENTIFIER, expValueCounter64Val Counter64 }

expValueInstance OBJECT-TYPE SYNTAX OBJECT IDENTIFIER, MAX-ACCESS not-accessible STATUS current DESCRIPTION

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"The final instance portion of a value's OID according to the wildcarding in instances of expObjectID for the expression.

If there is no wildcarding, the value is 0.0.

If there is wildcarding, the value is 0.0 followed by a value that the wildcard can take, thus defining one value instance for each real, possible value of the wildcard. So, for example, if the wildcard worked out to be an ifIndex, there is an expValueInstance for each applicable ifIndex." ::= { expValueEntry 1 }

expValueType OBJECT-TYPE SYNTAX INTEGER { counter32(1), unsignedOrGauge32(2), timeTicks(3), integer32(4), ipAddress(5), octetString(6), objectId(7), counter64(8) } MAX-ACCESS read-only STATUS current DESCRIPTION "The type of the value. One and only one of the value objects that follow will be valid based on this type." ::= { expValueEntry 2 }

expValueUnsigned32Val OBJECT-TYPE SYNTAX Unsigned32 -- (0..4294967295) MAX-ACCESS read-only STATUS current DESCRIPTION "The value when expValueType is one of 'counter32', 'unsignedOrGauge32', or 'timeTicks'." ::= { expValueEntry 3 }

expValueInteger32Val OBJECT-TYPE SYNTAX Integer32 -- (-2147483648..2147483647) MAX-ACCESS read-only STATUS current DESCRIPTION "The value when expValueType is 'integer32'." ::= { expValueEntry 4 }

expValueOctetStringVal OBJECT-TYPE SYNTAX OCTET STRING (SIZE (0..65536)) MAX-ACCESS read-only STATUS current

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DESCRIPTION "The value when expValueType is 'ipAddress' or 'octetString'." ::= { expValueEntry 5 }

expValueOidVal OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS current DESCRIPTION "The value when expValueType is 'objectId'." ::= { expValueEntry 6 }

expValueCounter64Val OBJECT-TYPE SYNTAX Counter64 -- (0..18446744073709551615) MAX-ACCESS read-only STATUS current DESCRIPTION "The value when expValueType is 'counter64'." ::= { expValueEntry 7 }

-- The compliance statements have yet to be written. The intent is -- that all objects are required. A proper subset -- of the MIB may disallow instance wildcards, deltaValues, or -- expObjectConditionals.

END

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5. Acknowledgements

This MIB contains considerable contributions from the RMON MIB, the Distributed Management Design Team (Andy Bierman, Maria Greene, Bob Stewart, and Steve Waldbusser), and colleagues at Cisco.

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6. References

[1] SNMPv2 Working Group, 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.

[2] McCloghrie, K., and M. Rose, Editors, "Management Information Base for Network Management of TCP/IP-based internets: MIB-II", STD 17, RFC 1213, March 1991.

[3] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", RFC 1157, May 1990.

[4] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996.

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7. Security Considerations

Security issues are not discussed in this memo.

8. Author's Address

Bob Stewart Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706

Phone: 408-526-4527 Email: bstewart@cisco.com

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Table of Contents

1 Abstract ........................................................ 2 2 The SNMP Network Management Framework ........................... 3 2.1 Object Definitions ............................................ 3 3 Overview ........................................................ 4 4 Definitions ..................................................... 5 5 Acknowledgements ................................................ 17 6 References ...................................................... 18 7 Security Considerations ......................................... 19 8 Author's Address ................................................ 19

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