RFC 1444
Conformance Statements for version 2 of the Simple Network Management Protocol (SNMPv2)
RFC 1444: Conformance Statements for version 2 of the Simple Network Management Protocol (SNMPv2) 🎀 (part 1 of 5)
Network Working Group 💖 Request for Comments: 1444, dated April 1993. Authors: J. Case (SNMP Research, Inc.), K. McCloghrie (Hughes LAN Systems), M. Rose (Dover Beach Consulting, Inc.), and S. Waldbusser (Carnegie Mellon University). It's an IAB standards track protocol 🌸, and the header doesn't list anything it obsoletes or updates. Okay, meet the crew! ✨
Status of this Memo 📜
okay so this RFC is an IAB standards track protocol for the Internet community, and it's asking for discussion and suggestions for improvements 💅. If you want to know where this protocol stands on the standardization ladder, check the current edition of the "IAB Official Protocol Standards". Distribution of this memo is unlimited, so share it with everyone 🦋.
Table of Contents 🧚
1 Introduction .......................................... 2
1.1 A Note on Terminology ............................... 2
2 Definitions ........................................... 3
3.1 The OBJECT-GROUP macro .............................. 3
3.2 The MODULE-COMPLIANCE macro ......................... 4
3.3 The AGENT-CAPABILITIES macro ........................ 7
3 Mapping of the OBJECT-GROUP macro ..................... 10
3.1 Mapping of the OBJECTS clause ....................... 10
3.2 Mapping of the STATUS clause ........................ 10
3.3 Mapping of the DESCRIPTION clause ................... 10
3.4 Mapping of the REFERENCE clause ..................... 11
3.5 Mapping of the OBJECT-GROUP value ................... 11
3.6 Usage Example ....................................... 12
4 Mapping of the MODULE-COMPLIANCE macro ................ 13
4.1 Mapping of the STATUS clause ........................ 13
4.2 Mapping of the DESCRIPTION clause ................... 13
4.3 Mapping of the REFERENCE clause ..................... 13
4.4 Mapping of the MODULE clause ........................ 13
4.4.1 Mapping of the MANDATORY-GROUPS clause ............ 14
4.4.2 Mapping of the GROUP clause ....................... 14
4.4.3 Mapping of the OBJECT clause ...................... 14
4.4.3.1 Mapping of the SYNTAX clause .................... 15
4.4.3.2 Mapping of the WRITE-SYNTAX clause .............. 15
4.4.3.3 Mapping of the MIN-ACCESS clause ................ 15
4.4.3.4 Mapping of the DESCRIPTION clause ............... 16
4.5 Mapping of the MODULE-COMPLIANCE value .............. 16
4.6 Usage Example ....................................... 17
5 Mapping of the AGENT-CAPABILITIES macro ............... 19
5.1 Mapping of the PRODUCT-RELEASE clause ............... 20
5.2 Mapping of the STATUS clause ........................ 20
5.3 Mapping of the DESCRIPTION clause ................... 20
5.4 Mapping of the REFERENCE clause ..................... 20
5.5 Mapping of the SUPPORTS clause ...................... 20
5.5.1 Mapping of the INCLUDES clause .................... 21
5.5.2 Mapping of the VARIATION clause ................... 21
5.5.2.1 Mapping of the SYNTAX clause .................... 21
5.5.2.2 Mapping of the WRITE-SYNTAX clause .............. 21
5.5.2.3 Mapping of the ACCESS clause .................... 22
5.5.2.4 Mapping of the CREATION-REQUIRES clause ......... 22
5.5.2.5 Mapping of the DEFVAL clause .................... 23
5.5.2.6 Mapping of the DESCRIPTION clause ............... 23
5.6 Mapping of the AGENT-CAPABILITIES value ............. 23
5.7 Usage Example ....................................... 24
6 Extending an Information Module ....................... 26
6.1 Conformance Groups .................................. 26
6.2 Compliance Definitions .............................. 26
6.3 Capabilities Definitions ............................ 26
7 Acknowledgements ...................................... 27
8 References ............................................ 31
9 Security Considerations ............................... 32
10 Authors' Addresses ................................... 321. Introduction ✨
okay so picture a network management system 🧚. It has several nodes, potentially loads of them, and each one has a processing entity called an agent that can get at management instrumentation. There's also at least one management station, plus a management protocol that moves management info between the agents and the stations 💜. Everything runs under an administrative framework that defines both authentication and authorization policies, so it's giving security and structure 🔥.
Management stations run management applications that monitor and control network elements 💅. Network elements are things like hosts, routers, terminal servers, and so on, and they get monitored and controlled through access to their management information 🌈.
That management information is seen as a collection of managed objects living in a virtual information store called the Management Information Base (MIB) 🦋. Related objects are grouped into MIB modules. These modules are written in a subset of OSI's Abstract Syntax Notation One (ASN.1) [1], which is called the Structure of Management Information (SMI) [2] 🤓.
Here's the vibe check: it can be really useful to define the acceptable lower bounds of implementation, along with the level of implementation that's actually achieved 🎯. That's the whole purpose of this document. It defines the notation used for those purposes, so this is the notation era 💖.
1.1. A Note on Terminology 🎀
For the sake of exposition, the original Internet-standard Network Management Framework, as described in RFCs 1155, 1157, and 1212, is called the SNMP version 1 framework (SNMPv1) 👑. The current one is called the SNMP version 2 framework (SNMPv2) ✨. So when you see SNMPv1 vs SNMPv2, that's the glow-up 💅🫶.
2. Definitions ✨
okay so this is the ASN.1 part, where the spec defines its own little vocab 🎀 Three macros live in here: OBJECT-GROUP, MODULE-COMPLIANCE, and AGENT-CAPABILITIES. Copy it exactly, no edits 🫶
SNMPv2-CONF DEFINITIONS ::= BEGIN
-- definitions for conformance groups
OBJECT-GROUP MACRO ::=
BEGIN
TYPE NOTATION ::=
ObjectsPart
"STATUS" Status
"DESCRIPTION" Text
ReferPart
VALUE NOTATION ::=
value(VALUE OBJECT IDENTIFIER)
ObjectsPart ::=
"OBJECTS" "{" Objects "}"
Objects ::=
Object
| Objects "," Object
Object ::=
value(Name ObjectName)
Status ::=
"current"
| "obsolete"
ReferPart ::=
"REFERENCE" Text
| empty
-- uses the NVT ASCII character set
Text ::= """" string """"
END
-- definitions for compliance statements
MODULE-COMPLIANCE MACRO ::=
BEGIN
TYPE NOTATION ::=
"STATUS" Status
"DESCRIPTION" Text
ReferPart
ModulePart
VALUE NOTATION ::=
value(VALUE OBJECT IDENTIFIER)
Status ::=
"current"
| "obsolete"
ReferPart ::=
"REFERENCE" Text
| empty
ModulePart ::=
Modules
| empty
Modules ::=
Module
| Modules Module
Module ::=
-- name of module --
"MODULE" ModuleName
MandatoryPart
CompliancePart
ModuleName ::=
modulereference ModuleIdentifier
-- must not be empty unless contained
-- in MIB Module
| empty
ModuleIdentifier ::=
value(ModuleID OBJECT IDENTIFIER)
| empty
MandatoryPart ::=
"MANDATORY-GROUPS" "{" Groups "}"
| empty
Groups ::=
Group
| Groups "," Group
Group ::=
value(Group OBJECT IDENTIFIER)
CompliancePart ::=
Compliances
| empty
Compliances ::=
Compliance
| Compliances Compliance
Compliance ::=
ComplianceGroup
| Object
ComplianceGroup ::=
"GROUP" value(Name OBJECT IDENTIFIER)
"DESCRIPTION" Text
Object ::=
"OBJECT" value(Name ObjectName)
SyntaxPart
WriteSyntaxPart
AccessPart
"DESCRIPTION" Text
-- must be a refinement for object's SYNTAX clause
SyntaxPart ::=
"SYNTAX" type(SYNTAX)
| empty
-- must be a refinement for object's SYNTAX clause
WriteSyntaxPart ::=
"WRITE-SYNTAX" type(WriteSYNTAX)
| empty
AccessPart ::=
"MIN-ACCESS" Access
| empty
Access ::=
"not-accessible"
| "read-only"
| "read-write"
| "read-create"
-- uses the NVT ASCII character set
Text ::= """" string """"
END
-- definitions for capabilities statements
AGENT-CAPABILITIES MACRO ::=
BEGIN
TYPE NOTATION ::=
"PRODUCT-RELEASE" Text
"STATUS" Status
"DESCRIPTION" Text
ReferPart
ModulePart
VALUE NOTATION ::=
-- agent's sysObjectID [3] or snmpORID [4]
value(VALUE OBJECT IDENTIFIER)
Status ::=
"current"
| "obsolete"
ReferPart ::=
"REFERENCE" Text
| empty
ModulePart ::=
Modules
| empty
Modules ::=
Module
| Modules Module
Module ::=
-- name of module --
"SUPPORTS" ModuleName
"INCLUDES" "{" Groups "}"
VariationPart
ModuleName ::=
identifier ModuleIdentifier
ModuleIdentifier ::=
value(ModuleID OBJECT IDENTIFIER)
| empty
Groups ::=
Group
| Groups "," Group
Group ::=
value(Name OBJECT IDENTIFIER)
VariationPart ::=
Variations
| empty
Variations ::=
Variation
| Variations Variation
Variation ::=
"VARIATION" value(Name ObjectName)
SyntaxPart
WriteSyntaxPart
AccessPart
CreationPart
DefValPart
"DESCRIPTION" Text
-- must be a refinement for object's SYNTAX clause
SyntaxPart ::=
"SYNTAX" type(SYNTAX)
| empty
-- must be a refinement for object's SYNTAX clause
WriteSyntaxPart ::=
"WRITE-SYNTAX" type(WriteSYNTAX)
| empty
AccessPart ::=
"ACCESS" Access
| empty
Access ::=
"not-implemented"
| "read-only"
| "read-write"
| "read-create"
-- following is for backward-compatibility only
| "write-only"
CreationPart ::=
"CREATION-REQUIRES" "{" Cells "}"
| empty
Cells ::=
Cell
| Cells "," Cell
Cell ::=
value(Cell ObjectName)
DefValPart ::=
"DEFVAL" "{" value(Defval ObjectSyntax) "}"
| empty
-- uses the NVT ASCII character set
Text ::= """" string """"
END
END3.1. Mapping of the OBJECT-GROUP macro
okay, so for conformance purposes it's super handy to group related managed objects together 🧚 That's what the OBJECT-GROUP macro is for. Fun fact: expanding the macro is something that happens conceptually while you're implementing, not at run-time 💜
Now, "implementing" an object is a whole vibe 🌸 An SNMPv2 entity acting as an agent must hand back a reasonably accurate value for retrieval operations. If the object is writable, then when a set operation comes in, the entity must be able to reasonably influence the underlying managed entity too 🔥 If an agent can't implement an object, the protocol gives it a way to return an exception or error, like noSuchObject [6] 🙈 And here's the big no-no: under no circumstances shall an SNMPv2 entity return a value for an object it doesn't implement. It must always return the appropriate exception or error, as described in the protocol specification [6] 💀
3.1.1. Mapping of the OBJECTS clause
the OBJECTS clause is a must-have 💅 It names each object inside the conformance group. Every named object must be defined in the same information module where the OBJECT-GROUP macro appears, and its MAX-ACCESS value has to be "read-only", "read-write", or "read-create" 🎀
3.1.2. Mapping of the STATUS clause
the STATUS clause must be present too, and it tells you whether the definition is current or historic ✨ The values "current" and "obsolete" are honestly self-explanatory, periodt 🦋
3.1.3. Mapping of the DESCRIPTION clause
the DESCRIPTION clause must be present, and it holds a textual definition of the group plus a description of any relations to other groups 🌈 Heads up: generic compliance requirements should not be stated in this clause. BUT implementation relationships between this group and other groups may be defined here 🫶
3.1.4. Mapping of the REFERENCE clause
the REFERENCE clause doesn't have to be there (need not be present, bestie) 🍓 It holds a textual cross-reference to a group defined in some other information module. This comes in clutch when you're de-osifying a MIB module that some other organization made 🧚
3.1.5. Mapping of the OBJECT-GROUP value
the value of an OBJECT-GROUP invocation is the group's name. That name is an OBJECT IDENTIFIER, which is an administratively assigned name 💜
3.1.6. Usage Example
let's look at how the system group from MIB-II [3] could be described 👑
systemGroup OBJECT-GROUP
OBJECTS { sysDescr, sysObjectID, sysUpTime,
sysContact, sysName, sysLocation,
sysServices }
STATUS current
DESCRIPTION
"The system group defines objects which are common
to all managed systems."
::= { mibIIGroups 1 }According to this invocation, the conformance group named
{ mibIIGroups 1 }contains 7 objects. Seven objects, bestie, that's a whole squad 🥹✨
4. Mapping of the MODULE-COMPLIANCE macro ✨
Okay bestie, so the MODULE-COMPLIANCE macro is how we spell out a minimum set of requirements for implementing one or more MIB modules 💅. Important detail: the expansion of this macro conceptually happens during implementation and not during run-time 🙈. Also, every "standard" MIB module needs a matching MODULE-COMPLIANCE specification 🎀, either in the same information module or in a companion one 🫶.
4.1. Mapping of the STATUS clause
The STATUS clause must be present 💖. It tells you whether a definition is current or historic 🌸. "current" and "obsolete" are honestly self-explanatory 💀. "deprecated" means the object is obsolete, but an implementor may wish to support it anyway to keep things interoperable with older implementations 🧚.
4.2. Mapping of the DESCRIPTION clause
The DESCRIPTION clause must be present 📝. It's the written definition of this compliance statement, and it should carry any information that would otherwise be communicated in the ASN.1 commentary annotations attached to the statement ✨.
4.3. Mapping of the REFERENCE clause
The REFERENCE clause need not be present 🦋. It's a textual cross-reference to a compliance statement defined in some other information module 🌈.
4.4. Mapping of the MODULE clause
The MODULE clause must be present, and it gets used again and again 🔁 to name each MIB module that compliance requirements are being specified for 👑. Each MIB module is named by its module name, and optionally by its associated OBJECT IDENTIFIER as well 🍓. Here's the cute part: the module name can be omitted when the MODULE-COMPLIANCE invocation happens inside a MIB module, because then it refers to the encompassing MIB module 🥰.
4.4.1. Mapping of the MANDATORY-GROUPS clause
The MANDATORY-GROUPS clause need not be present 🌷. It names the one or more groups within the correspondent MIB module that are unconditionally mandatory for implementation 🔥. If a SNMPv2 entity acting in an agent role claims compliance to the MIB module, then it must implement each and every object within each conformance group listed 🚨. Put simply, if a SNMPv2 entity returns a noSuchObject exception in response to a management protocol get operation [5] for any object within any mandatory conformance group for every MIB view, then that SNMPv2 entity is not a conformant implementation of the MIB module 💅💀.
4.4.2. Mapping of the GROUP clause
The GROUP clause need not be present 🌸. It gets used repeatedly to name each MIB group that is conditionally mandatory or unconditionally optional for compliance to the MIB module 🦋. A MIB group named in a GROUP clause must be absent from the correspondent MANDATORY-GROUPS clause 🙅♀️.
Conditionally mandatory groups include those that are mandatory only if a particular protocol is implemented, or only if another group is implemented 🧠. A GROUP clause's DESCRIPTION specifies the conditions under which the group is conditionally mandatory ✨.
A MIB group that is named in neither a MANDATORY-GROUPS clause nor a GROUP clause is unconditionally optional for compliance to the MIB module 🌈.
4.4.3. Mapping of the OBJECT clause
The OBJECT clause need not be present 🎀. It gets used repeatedly to name each MIB object that has a refined requirement for compliance with respect to the MIB module definition 🔍. The MIB object must be present in one of the conformance groups named in the correspondent MANDATORY-GROUPS clause or GROUP clauses 💜.
4.4.3.1. Mapping of the SYNTAX clause
The SYNTAX clause need not be present 🌷. It provides a refined SYNTAX for the object named in the correspondent OBJECT clause 🧁. Note that if this clause and a WRITE-SYNTAX clause are both present, then this clause only applies when instances of the object named in the correspondent OBJECT clause are read 👀.
Consult Section 10 of [2] for more information on refined syntax 📚.
4.4.3.2. Mapping of the WRITE-SYNTAX clause
The WRITE-SYNTAX clause need not be present 🌸. It provides a refined SYNTAX for the object named in the correspondent OBJECT clause when instances of that object are written ✍️.
Consult Section 10 of [2] for more information on refined syntax 📚.
4.4.3.3. Mapping of the MIN-ACCESS clause
The MIN-ACCESS clause need not be present 🦋. It defines the minimal level of access for the object named in the correspondent OBJECT clause 🔒. If this clause is absent, the minimal level of access is the same as the maximal level specified in the correspondent invocation of the OBJECT-TYPE macro ✨. If it is present, this clause must not specify a greater level of access than is specified in the correspondent invocation of the OBJECT-TYPE macro 🚫.
The level of access for certain types of objects is fixed according to their syntax definition 🧊. These types are: conceptual tables and rows, auxiliary objects, and objects with the syntax of Counter32, Counter64, or certain types of textual conventions (e.g., RowStatus [6]) 📋. A MIN-ACCESS clause should not be present for such objects 🙈.
An implementation is compliant if the level of access it provides is greater or equal to the minimal level in the MODULE-COMPLIANCE macro and less or equal to the maximal level in the OBJECT-TYPE macro 💯.
4.4.3.4. Mapping of the DESCRIPTION clause
The DESCRIPTION clause must be present for each use of the GROUP or OBJECT clause 📝. For an OBJECT clause, it contains a textual description of the refined compliance requirement 🎯. For a GROUP clause, it contains a textual description of the conditions under which the group is conditionally mandatory or unconditionally optional 🧩.
4.5. Mapping of the MODULE-COMPLIANCE value
The value of an invocation of the MODULE-COMPLIANCE macro is an OBJECT IDENTIFIER 🆔. Because of that, this value may be authoritatively used when referring to the compliance statement embodied by that invocation of the macro 👑.
4.6. Usage Example
Let's look at how a compliance statement might be included at the end of the MIB-II document [3], assuming conformance groups were defined in it 🎀:
mibIICompliances
OBJECT IDENTIFIER ::= { mibIIConformance 1 }
mibIIGroups OBJECT IDENTIFIER ::= { mibIIConformance 2 }
mibIICompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMPv2 entities
residing on systems which implement the Internet
suite of protocols."
MODULE -- compliance to the containing MIB module
MANDATORY-GROUPS { systemGroup, snmpGroup }
GROUP interfacesGroup
DESCRIPTION
"The interfaces group is mandatory for systems
with network interfaces."
GROUP ipGroup
DESCRIPTION
"The ip group is mandatory for systems which
implement IP."
GROUP icmpGroup
DESCRIPTION
"The icmp group is mandatory for systems which
implement ICMP."
GROUP tcpGroup
DESCRIPTION
"The tcp group is mandatory for systems which
implement TCP."
OBJECT tcpConnState
MIN-ACCESS read-only
DESCRIPTION
"A compliant system need not allow
write-access to this object."
GROUP udpGroup
DESCRIPTION
"The udp group is mandatory for systems which
implement UDP."
GROUP egpGroup
DESCRIPTION
"The egp group is mandatory for systems which
implement EGP."
::= { mibIICompliances 1 }So according to this invocation, to claim alignment with the compliance statement named
{ mibIICompliances 1 }a system must implement RFC1213's systemGroup and snmpGroup conformance groups 🫶. If the system implements any network interfaces, then RFC1213's interfacesGroup conformance group must be implemented 🌐. Further, if the system implements any of the IP, ICMP, TCP, UDP, or EGP protocols, then the correspondent conformance group in RFC1213 must be implemented, if compliance is to be claimed 🧠. Finally, although RFC1213 specifies that it makes "protocol sense" for the tcpConnState object to be writable, this specification allows the system to permit only read-only access and still claim compliance 🙌✨.
5. Mapping of the AGENT-CAPABILITIES macro 🧚
The AGENT-CAPABILITIES macro is used to convey the capabilities present in a SNMPv2 entity acting in an agent role 🤖. Again, the expansion of the AGENT-CAPABILITIES macro conceptually happens during implementation and not during run-time ⏳.
Okay, so when a MIB module is written, it gets divided into units of conformance called groups 🧩. If a SNMPv2 entity acting in an agent role claims to implement a group, then it must implement each and every object within that group 💯. Of course, for whatever reason, a SNMPv2 entity might implement only a subset of the groups within a MIB module 🫠. Also, the definition of some MIB objects leaves some aspects of the definition to the discretion of an implementor 🎨.
Practical experience has shown a need for concisely describing the capabilities of an agent with respect to one or more MIB modules 📣. The AGENT-CAPABILITIES macro lets an agent implementor describe the precise level of support an agent claims for a MIB group 🎯, and bind that description to the value of sysObjectID [3] associated with the agent, or to the value of an instance of the snmpORID object in the snmpORTable [4] 🔗. In particular, some objects may have restricted or augmented syntax or access-levels 🌸.
So if the AGENT-CAPABILITIES invocation gets handed to a management-station implementor, that implementor can build management apps that optimize themselves for each agent they talk to. ✨ For example, the management station can keep a database of these invocations. When it talks to an agent, it grabs the agent's sysObjectID [3], checks the database, and if there's a match, the app can tune how it behaves. Main character energy 💅
Heads up though: sysObjectID alone may not always cover every MIB object an agent can access 🙈 This happens when the agent dynamically learns what objects it supports. In those cases, the snmpORID column of snmpORTable [4] has extra info that SHOULD be used alongside sysObjectID.
Also, the AGENT-CAPABILITIES macro describes refinements or variations relative to OBJECT-TYPE macros in MIB modules, NOT relative to MODULE-COMPLIANCE macros in compliance statements. 🎀 Don't mix those up, bestie!
5.1. Mapping of the PRODUCT-RELEASE clause
The PRODUCT-RELEASE clause MUST be present 🫶 It holds a textual description of the product release that includes this agent.
5.2. Mapping of the STATUS clause
The STATUS clause MUST be present, and it says whether this definition is current or historic 🦋
The values "current" and "obsolete" are self-explanatory 💖 The "deprecated" value means the object is obsolete, but an implementor may wish to keep supporting it to help with interoperability with older implementations 🧚
5.3. Mapping of the DESCRIPTION clause
The DESCRIPTION clause MUST be present and holds a textual description of this agent 🌸
5.4. Mapping of the REFERENCE clause
The REFERENCE clause need not be present 🍓 It holds a textual cross-reference to a capability statement defined in some other information module.
5.5. Mapping of the SUPPORTS clause
The SUPPORTS clause need not be present, but it's used again and again to name each MIB module the agent claims a complete or partial implementation of ✨ Each MIB module is named by its module name and, optionally, by its associated OBJECT IDENTIFIER too.
5.5.1. Mapping of the INCLUDES clause
The INCLUDES clause MUST be present for each use of the SUPPORTS clause. It names each MIB group associated with the SUPPORT clause that the agent claims to implement 💜
5.5.2. Mapping of the VARIATION clause
The VARIATION clause need not be present, but it's repeatedly used to name each MIB object the agent implements in some variant or refined way compared to the matching OBJECT-TYPE invocation 🔥
Note that the variation concept is meant for generic implementation restrictions. So if the variation for an object depends on the values of other objects, that SHOULD be noted in the appropriate DESCRIPTION clause 👑
5.5.2.1. Mapping of the SYNTAX clause
The SYNTAX clause need not be present. It's used to provide a refined SYNTAX for the object named in the matching VARIATION clause. Note that if this clause and a WRITE-SYNTAX clause are both present, then this clause only applies when instances of the object named in the matching VARIATION clause are read 👀
For more on refined syntax, consult Section 10 of [2] 📚
5.5.2.2. Mapping of the WRITE-SYNTAX clause
The WRITE-SYNTAX clause need not be present. It's used to provide a refined SYNTAX for the object named in the matching VARIATION clause when instances of that object are written ✍️
For more on refined syntax, consult Section 10 of [2] 📚
5.5.2.3. Mapping of the ACCESS clause
The ACCESS clause need not be present. It's used to show that the agent provides less than the maximal level of access to the object named in the matching VARIATION clause 🙅♀️
The value "not-implemented" means the agent doesn't implement the object, and in the ordering of possible values it's equivalent to "not-accessible" 💀
The value "write-only" is only there for backward compatibility, and it SHALL NOT be used for newly-defined object types 🚫 In the ordering of possible values, "write-only" is less than "not-accessible".
5.5.2.4. Mapping of the CREATION-REQUIRES clause
The CREATION-REQUIRES clause need not be present. It names the columnar objects of a conceptual row that MUST be explicitly assigned values, through a management protocol set operation, before the agent will allow the instance of the status column of that row to be set to `active'. (Check out the RowStatus definition [6] for the deets 🧐)
If the conceptual row doesn't have a status column (meaning the objects for that conceptual table were defined using the mechanisms in [7,8]), then the CREATION-REQUIRES clause, which need not be present, names the columnar objects of a conceptual row that MUST be explicitly assigned values, through a management protocol set operation, before the agent will create new instances of objects in that row 🌈
This clause MUST NOT present unless the object named in the matching VARIATION clause is a conceptual row, meaning it has a syntax that resolves to a SEQUENCE containing columnar objects. The objects named in this clause will usually refer to columnar objects in that row, but objects unrelated to the conceptual row may also be specified 💫
All objects named in the CREATION-REQUIRES clause for a conceptual row that are columnar objects of that row MUST have an access level of "read-create" 🔐
5.5.2.5. Mapping of the DEFVAL clause
The DEFVAL clause need not be present. It's used to provide a refined DEFVAL value for the object named in the matching VARIATION clause. Its semantics are identical to those of the OBJECT-TYPE macro's DEFVAL clause 🍭
5.5.2.6. Mapping of the DESCRIPTION clause
The DESCRIPTION clause MUST be present for each use of the VARIATION clause. It holds a textual description of the variant or refined implementation 📝
5.6. Mapping of the AGENT-CAPABILITIES value
The value of an AGENT-CAPABILITIES invocation is an OBJECT IDENTIFIER, which names the value of sysObjectID [3] or snmpORID [4] for which this capabilities statement is valid 🆔
5.7. Usage Example
Okay, let's look at how a capabilities statement for an agent might be written 🎀
exampleAgent AGENT-CAPABILITIES
PRODUCT-RELEASE "ACME Agent release 1.1 for 4BSD"
STATUS current
DESCRIPTION "ACME agent for 4BSD"
SUPPORTS RFC1213-MIB
INCLUDES { systemGroup, interfacesGroup,
atGroup, ipGroup, icmpGroup,
tcpGroup, udpGroup, snmpGroup }
VARIATION ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
DESCRIPTION "Unable to set test mode on 4BSD"
VARIATION ifOperStatus
SYNTAX INTEGER { up(1), down(2) }
DESCRIPTION "Information limited on 4BSD"
VARIATION atEntry
CREATION-REQUIRES { atPhysAddress }
DESCRIPTION "Address mappings on 4BSD require
both protocol and media addresses"
VARIATION ipDefaultTTL
SYNTAX INTEGER (255..255)
DESCRIPTION "Hard-wired on 4BSD"
VARIATION ipInAddrErrors
ACCESS not-implemented
DESCRIPTION "Information not available on 4BSD"
VARIATION ipRouteType
SYNTAX INTEGER { direct(3), indirect(4) }
WRITE-SYNTAX INTEGER { invalid(2), direct(3),
indirect(4) }
DESCRIPTION "Information limited on 4BSD"
VARIATION tcpConnState
ACCESS read-only
DESCRIPTION "Unable to set this on 4BSD"
SUPPORTS EVAL-MIB
INCLUDES { functionsGroup, expressionsGroup }
VARIATION exprEntry
CREATION-REQUIRES { evalString }
DESCRIPTION "Conceptual row creation supported"
::= { acmeAgents 1 }So according to this invocation, an agent whose sysObjectID (or snmpORID) value is
{ acmeAgents 1 }supports two MIB modules 👯♀️
From MIB-II, all conformance groups except the egpGroup conformance group are supported 🙌 However, the object ipInAddrErrors is not implemented, and these objects have a restricted syntax:
ifAdminStatus
ifOperStatus
ipDefaultTTL
ipRouteTypeAnd this object is only available for reading:
tcpConnStateNote that for ipRouteType, the set of values that may be read is different from the set of values that may be written 🔄 Finally, when creating a new instance in the atTable, the set-request MUST create an instance of atPhysAddress.
From the EVAL-MIB, all the objects in the functionsGroup and expressionsGroup conformance groups are supported, without variation 🧚 On top of that, creating new instances in the expr table is supported 🌟
6. Extending an Information Module 🦋
okay so, real talk, once people start using a published information module, it's totally normal to want to glow up and revise it 💅✨
Section 10 of [2] is the official rulebook for extending an information module 📖 The rest of this section explains how conformance groups, compliance statements, and capabilities statements can be extended too 🫶
6.1. Conformance Groups 🌸
Okay this one's serious bestie 😭 If you make any non-editorial change to any clause of an object group, the OBJECT IDENTIFIER value for that object group MUST also be changed, along with its associated descriptor. No skipping this! 🙅♀️
6.2. Compliance Definitions 🎀
Same energy here 💜 If you make any non-editorial change to any clause of a compliance definition, the OBJECT IDENTIFIER value for that compliance definition MUST also be changed, along with its associated descriptor. Literally the same rule, no exceptions 💖
6.3. Capabilities Definitions 🧚
And again for capabilities definitions 🍓 If any non-editorial change is made to any clause of a capabilities definition, the OBJECT IDENTIFIER value for that capabilities definition MUST also be changed, along with its associated descriptor. It's giving consistency, periodt ✨
7. Acknowledgements 🫶
The section on compliance statements is based, in part, on a conversation with James R. Davin in December, 1990 💬
The section on capabilities statements is based, in part, on RFC 1303 🌈
And finally, huge shoutout to the comments from the SNMP version 2 working group 👑 💖 Here's the whole squad:
Beth Adams, Network Management Forum
Steve Alexander, INTERACTIVE Systems Corporation
David Arneson, Cabletron Systems
Toshiya Asaba
Fred Baker, ACC
Jim Barnes, Xylogics, Inc.
Brian Bataille
Andy Bierman, SynOptics Communications, Inc.
Uri Blumenthal, IBM Corporation
Fred Bohle, Interlink
Jack Brown
Theodore Brunner, Bellcore
Stephen F. Bush, GE Information Services
Jeffrey D. Case, University of Tennessee, Knoxville
John Chang, IBM Corporation
Szusin Chen, Sun Microsystems
Robert Ching
Chris Chiotasso, Ungermann-Bass
Bobby A. Clay, NASA/Boeing
John Cooke, Chipcom
Tracy Cox, Bellcore
Juan Cruz, Datability, Inc.
David Cullerot, Cabletron Systems
Cathy Cunningham, Microcom
James R. (Chuck) Davin, Bellcore
Michael Davis, Clearpoint
Mike Davison, FiberCom
Cynthia DellaTorre, MITRE
Taso N. Devetzis, Bellcore
Manual Diaz, DAVID Systems, Inc.
Jon Dreyer, Sun Microsystems
David Engel, Optical Data Systems
Mike Erlinger, Lexcel
Roger Fajman, NIH
Daniel Fauvarque, Sun Microsystems
Karen Frisa, CMU
Shari Galitzer, MITRE
Shawn Gallagher, Digital Equipment Corporation
Richard Graveman, Bellcore
Maria Greene, Xyplex, Inc.
Michel Guittet, Apple
Robert Gutierrez, NASA
Bill Hagerty, Cabletron Systems
Gary W. Haney, Martin Marietta Energy Systems
Patrick Hanil, Nokia Telecommunications
Matt Hecht, SNMP Research, Inc.
Edward A. Heiner, Jr., Synernetics Inc.
Susan E. Hicks, Martin Marietta Energy Systems
Geral Holzhauer, Apple
John Hopprich, DAVID Systems, Inc.
Jeff Hughes, Hewlett-Packard
Robin Iddon, Axon Networks, Inc.
David Itusak
Kevin M. Jackson, Concord Communications, Inc.
Ole J. Jacobsen, Interop Company
Ronald Jacoby, Silicon Graphics, Inc.
Satish Joshi, SynOptics Communications, Inc.
Frank Kastenholz, FTP Software
Mark Kepke, Hewlett-Packard
Ken Key, SNMP Research, Inc.
Zbiginew Kielczewski, Eicon
Jongyeoi Kim
Andrew Knutsen, The Santa Cruz Operation
Michael L. Kornegay, VisiSoft
Deirdre C. Kostik, Bellcore
Cheryl Krupczak, Georgia Tech
Mark S. Lewis, Telebit
David Lin
David Lindemulder, AT&T/NCR
Ben Lisowski, Sprint
David Liu, Bell-Northern Research
John Lunny, The Wollongong Group
Robert C. Lushbaugh Martin, Marietta Energy Systems
Michael Luufer, BBN
Carl Madison, Star-Tek, Inc.
Keith McCloghrie, Hughes LAN Systems
Evan McGinnis, 3Com Corporation
Bill McKenzie, IBM Corporation
Donna McMaster, SynOptics Communications, Inc.
John Medicke, IBM Corporation
Doug Miller, Telebit
Dave Minnich, FiberCom
Mohammad Mirhakkak, MITRE
Rohit Mital, Protools
George Mouradian, AT&T Bell Labs
Patrick Mullaney, Cabletron Systems
Dan Myers, 3Com Corporation
Rina Nathaniel, Rad Network Devices Ltd.
Hien V. Nguyen, Sprint
Mo Nikain
Tom Nisbet
William B. Norton, MERIT
Steve Onishi, Wellfleet Communications, Inc.
David T. Perkins, SynOptics Communications, Inc.
Carl Powell, BBN
Ilan Raab, SynOptics Communications, Inc.
Richard Ramons, AT&T
Venkat D. Rangan, Metric Network Systems, Inc.
Louise Reingold, Sprint
Sam Roberts, Farallon Computing, Inc.
Kary Robertson, Concord Communications, Inc.
Dan Romascanu, Lannet Data Communications Ltd.
Marshall T. Rose, Dover Beach Consulting, Inc.
Shawn A. Routhier, Epilogue Technology Corporation
Chris Rozman
Asaf Rubissa, Fibronics
Jon Saperia, Digital Equipment Corporation
Michael Sapich
Mike Scanlon, Interlan
Sam Schaen, MITRE
John Seligson, Ultra Network Technologies
Paul A. Serice, Corporation for Open Systems
Chris Shaw, Banyan Systems
Timon Sloane
Robert Snyder, Cisco Systems
Joo Young Song
Roy Spitier, Sprint
Einar Stefferud, Network Management Associates
John Stephens, Cayman Systems, Inc.
Robert L. Stewart, Xyplex, Inc. (chair)
Kaj Tesink, Bellcore
Dean Throop, Data General
Ahmet Tuncay, France Telecom-CNET
Maurice Turcotte, Racal Datacom
Warren Vik, INTERACTIVE Systems Corporation
Yannis Viniotis
Steven L. Waldbusser, Carnegie Mellon Universitty
Timothy M. Walden, ACC
Alice Wang, Sun Microsystems
James Watt, Newbridge
Luanne Waul, Timeplex
Donald E. Westlake III, Digital Equipment Corporation
Gerry White
Bert Wijnen, IBM Corporation
Peter Wilson, 3Com Corporation
Steven Wong, Digital Equipment Corporation
Randy Worzella, IBM Corporation
Daniel Woycke, MITRE
Honda Wu
Jeff Yarnell, Protools
Chris Young, Cabletron
Kiho Yum, 3Com Corporation8. References 📚
[1] Information processing systems - Open Systems
Interconnection - Specification of Abstract Syntax
Notation One (ASN.1), International Organization for
Standardization. International Standard 8824, (December,
1987).
[2] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Structure of Management Information for version 2 of the
Simple Network Management Protocol (SNMPv2)", RFC 1442,
SNMP Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[3] McCloghrie, K., and Rose, M., "Management Information
Base for Network Management of TCP/IP-based internets:
MIB-II", STD 17, RFC 1213, March 1991.
[4] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Management Information Base for version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1450, SNMP
Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[5] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Protocol Operations for version 2 of the Simple Network
Management Protocol (SNMPv2)", RFC 1448, SNMP Research,
Inc., Hughes LAN Systems, Dover Beach Consulting, Inc.,
Carnegie Mellon University, April 1993.
[6] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Textual Conventions for version 2 of the the Simple
Network Management Protocol (SNMPv2)", RFC 1443, SNMP
Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.
[7] Rose, M., and McCloghrie, K., "Structure and
Identification of Management Information for TCP/IP-based
internets", STD 16, RFC 1155, May 1990.
[8] Rose, M., and McCloghrie, K., "Concise MIB Definitions",
STD 16, RFC 1212, March 1991.9. Security Considerations 🔐
Okay, big moment: security issues are not discussed in this memo. 🙈 Nothing to see here on that front, but stay aware of it anyway 💀
10. Authors' Addresses 💌
Jeffrey D. Case
SNMP Research, Inc.
3001 Kimberlin Heights Rd.
Knoxville, TN 37920-9716
US
Phone: +1 615 573 1434
Email: case@snmp.com
Keith McCloghrie
Hughes LAN Systems
1225 Charleston Road
Mountain View, CA 94043
US
Phone: +1 415 966 7934
Email: kzm@hls.com
Marshall T. Rose
Dover Beach Consulting, Inc.
420 Whisman Court
Mountain View, CA 94043-2186
US
Phone: +1 415 968 1052
Email: mrose@dbc.mtview.ca.us
Steven Waldbusser
Carnegie Mellon University
4910 Forbes Ave
Pittsburgh, PA 15213
US
Phone: +1 412 268 6628
Email: waldbusser@cmu.edu📦 where this page comes from
- ietf: rfc1444 1993-04
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms