| Rfc | 3780 |
|---|
| Title | SMIng - Next Generation Structure of Management Information |
|---|
| Author | F.
Strauss, J. Schoenwaelder |
|---|
| Date | May 2004 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | EXPERIMENTAL |
|---|
|
Network Working Group F. Strauss
Request for Comments: 3780 TU Braunschweig
Category: Experimental J. Schoenwaelder
International University Bremen
May 2004
SMIng - Next Generation Structure of Management Information
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This memo defines the base SMIng (Structure of Management
Information, Next Generation) language. SMIng is a data definition
language that provides a protocol-independent representation for
management information. Separate RFCs define mappings of SMIng to
specific management protocols, including SNMP.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. The History of SMIng . . . . . . . . . . . . . . . . . . 4
1.2. Terms of Requirement Levels. . . . . . . . . . . . . . . 5
2. SMIng Data Modeling. . . . . . . . . . . . . . . . . . . . . . 5
2.1. Identifiers. . . . . . . . . . . . . . . . . . . . . . . 6
3. Base Types and Derived Types . . . . . . . . . . . . . . . . . 7
3.1. OctetString. . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Pointer. . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. ObjectIdentifier . . . . . . . . . . . . . . . . . . . . 9
3.4. Integer32. . . . . . . . . . . . . . . . . . . . . . . . 10
3.5. Integer64. . . . . . . . . . . . . . . . . . . . . . . . 11
3.6. Unsigned32 . . . . . . . . . . . . . . . . . . . . . . . 12
3.7. Unsigned64 . . . . . . . . . . . . . . . . . . . . . . . 13
3.8. Float32. . . . . . . . . . . . . . . . . . . . . . . . . 13
3.9. Float64. . . . . . . . . . . . . . . . . . . . . . . . . 14
3.10. Float128 . . . . . . . . . . . . . . . . . . . . . . . . 15
3.11. Enumeration. . . . . . . . . . . . . . . . . . . . . . . 17
3.12. Bits . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.4. The class' event Statement . . . . . . . . . . . . . . . 35
9.4.1. The event's status Statement. . . . . . . . . . . 35
9.4.2. The event's description Statement . . . . . . . . 35
9.4.3. The event's reference Statement . . . . . . . . . 36
9.5. The class' status Statement. . . . . . . . . . . . . . . 36
9.6. The class' description Statement . . . . . . . . . . . . 36
9.7. The class' reference Statement . . . . . . . . . . . . . 37
9.8. Usage Example. . . . . . . . . . . . . . . . . . . . . . 37
10. Extending a Module . . . . . . . . . . . . . . . . . . . . . . 38
11. SMIng Language Extensibility . . . . . . . . . . . . . . . . . 39
12. Security Considerations. . . . . . . . . . . . . . . . . . . . 41
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 41
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42
14.1. Normative References . . . . . . . . . . . . . . . . . . 42
14.2. Informative References . . . . . . . . . . . . . . . . . 42
Appendix A. NMRG-SMING Module . . . . . . . . . . . . . . . . . . 44
Appendix B. SMIng ABNF Grammar. . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 63
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 64
1. Introduction
In traditional management systems, management information is viewed
as a collection of managed objects, residing in a virtual information
store, termed the Management Information Base (MIB). Collections of
related objects are defined in MIB modules. These modules are
written in conformance with a specification language, the Structure
of Management Information (SMI). There are different versions of the
SMI. The SMI version 1 (SMIv1) is defined in [RFC1155], [RFC1212],
[RFC1215], and the SMI version 2 (SMIv2) in [RFC2578], [RFC2579], and
[RFC2580]. Both are based on adapted subsets of OSI's Abstract
Syntax Notation One, ASN.1 [ASN1].
In a similar fashion, policy provisioning information is viewed as a
collection of Provisioning Classes (PRCs) and Provisioning Instances
(PRIs) residing in a virtual information store, termed the Policy
Information Base (PIB). Collections of related Provisioning Classes
are defined in PIB modules. PIB modules are written using the
Structure of Policy Provisioning Information (SPPI) [RFC3159] which
is an adapted subset of SMIv2.
The SMIv1 and the SMIv2 are bound to the Simple Network Management
Protocol (SNMP) [RFC3411], while the SPPI is bound to the Common Open
Policy Service Provisioning (COPS-PR) Protocol [RFC3084]. Even
though the languages have common rules, it is hard to use common data
definitions with both protocols. It is the purpose of this document
to define a common data definition language, named SMIng, that can
formally specify data models independent of specific protocols and
applications. The appendix of this document defines a core module
that supplies common SMIng definitions.
A companion document contains an SMIng language extension to define
SNMP specific mappings of SMIng definitions in compatibility with
SMIv2 MIB modules [RFC3781]. Additional language extensions may be
added in the future, e.g., to define COPS-PR specific mappings of
SMIng definitions in a way that is compatible with SPPI PIBs.
Section 2 gives an overview of the basic concepts of data modeling
using SMIng, while the subsequent sections present the concepts of
the SMIng language in detail: the base types, the SMIng file
structure, and all SMIng core statements.
The remainder of the document describes extensibility features of the
language and rules to follow when changes are applied to a module.
Appendix B contains the grammar of SMIng in ABNF [RFC2234] notation.
1.1. The History of SMIng
SMIng started in 1999 as a research project to address some drawbacks
of SMIv2, the current data modeling language for management
information bases. Primarily, its partial dependence on ASN.1 and a
number of exception rules turned out to be problematic. In 2000, the
work was handed over to the IRTF Network Management Research Group
where it was significantly detailed. Since the work of the RAP
Working Group on COPS-PR and SPPI emerged in 1999/2000, SMIng was
split into two parts: a core data definition language (defined in
this document) and protocol mappings to allow the application of core
definitions through (potentially) multiple management protocols. The
replacement of SMIv2 and SPPI by a single merged data definition
language was also a primary goal of the IETF SMING Working Group that
was chartered at the end of 2000.
The requirements for a new data definition language were discussed
several times within the IETF SMING Working Group and changed
significantly over time [RFC3216], so that another proposal (in
addition to SMIng), named SMI Data Structures (SMI-DS), was presented
to the Working Group. In the end, neither of the two proposals found
enough consensus and support, and the attempt to merge the existing
concepts did not succeed, resulting in the Working Group being closed
down in April 2003.
In order to record the work of the NMRG (Network Management Research
Group) on SMIng, this memo and the accompanying memo on the SNMP
protocol mapping [RFC3781] have been published for informational
purposes.
Note that throughout these documents, the term "SMIng" refers to the
specific data modeling language that is specified in this document,
whereas the term "SMING" refers to the general effort within the IETF
Working Group to define a new management data definition language as
an SMIv2 successor and probably an SPPI merger, for which "SMIng" and
"SMI-DS" were two specific proposals.
1.2. Terms of Requirement Levels
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. SMIng Data Modeling
SMIng is a language designed to specify management information in a
structured way readable to computer programs, e.g., MIB compilers, as
well as to human readers.
Management information is modeled in classes. Classes can be defined
from scratch or by derivation from a parent class. Derivation from
multiple parent classes is not possible. The concept of classes is
described in Section 9.
Each class has a number of attributes. Each attribute represents an
atomic piece of information of a base type, a sub-type of a base
type, or another class. The concept of attributes is described in
Section 9.2.
The base types of SMIng include signed and unsigned integers, octet
strings, enumeration types, bitset types, and pointers. Pointers are
references to class instances, attributes of class instances, or
arbitrary identities. The SMIng type system is described in Section
3.
Related class and type definitions are defined in modules. A module
may refer to definitions from other modules by importing identifiers
from those modules. Each module may serve one or multiple purposes:
o the definition of management classes,
o the definition of events,
o the definition of derived types,
o the definition of arbitrary untyped identities serving as values
of pointers,
o the definition of SMIng extensions allowing the local module or
other modules to specify information beyond the scope of the base
SMIng in a machine readable notation. Some extensions for the
application of SMIng in the SNMP framework are defined in
[RFC3781],
o the definition of information beyond the scope of the base SMIng
statements, based on locally defined or imported SMIng extensions.
Each module is identified by an upper-case identifier. The names of
all standard modules must be unique (but different versions of the
same module should have the same name). Developers of enterprise
modules are encouraged to choose names for their modules that will
have a low probability of colliding with standard or other enterprise
modules, e.g., by using the enterprise or organization name as a
prefix.
2.1. Identifiers
Identifiers are used to identify different kinds of SMIng items by
name. Each identifier is valid in a namespace which depends on the
type of the SMIng item being defined:
o The global namespace contains all module identifiers.
o Each module defines a new namespace. A module's namespace may
contain definitions of extension identifiers, derived type
identifiers, identity identifiers, and class identifiers.
Furthermore, a module may import identifiers of these kinds from
other modules. All these identifiers are also visible within all
inner namespaces of the module.
o Each class within a module defines a new namespace. A class'
namespace may contain definitions of attribute identifiers and
event identifiers.
o Each enumeration type and bitset type defines a new namespace of
its named numbers. These named numbers are visible in each
expression of a corresponding value, e.g., default values and
sub-typing restrictions.
o Extensions may define additional namespaces and have additional
rules of other namespaces' visibility.
Within every namespace each identifier MUST be unique.
Each identifier starts with an upper-case or lower-case character,
dependent on the kind of SMIng item, followed by zero or more
letters, digits, and hyphens.
All identifiers defined in a namespace MUST be unique and SHOULD NOT
only differ in case. Identifiers MUST NOT exceed 64 characters in
length. Furthermore, the set of all identifiers defined in all
modules of a single standardization body or organization SHOULD be
unique and mnemonic. This promotes a common language for humans to
use when discussing a module.
To reference an item that is defined in the local module, its
definition MUST sequentially precede the reference. Thus, there MUST
NOT be any forward references.
To reference an item that is defined in an external module it MUST be
imported (Section 5.1). Identifiers that are neither defined nor
imported MUST NOT be visible in the local module.
When identifiers from external modules are referenced, there is the
possibility of name collisions. As such, if different items with the
same identifier are imported or if imported identifiers collide with
identifiers of locally defined items, then this ambiguity is resolved
by prefixing those identifiers with the names of their modules and
the namespace operator `::', i.e., `Module::item'. Of course, this
notation can be used to refer to identifiers even when there is no
name collision.
Note that SMIng core language keywords MUST NOT be imported. See the
`...Keyword' rules of the SMIng ABNF grammar in Appendix B for a list
of those keywords.
3. Base Types and Derived Types
SMIng has a set of base types, similar to those of many programming
languages, but with some differences due to special requirements from
the management information model.
Additional types may be defined, derived from those base types or
from other derived types. Derived types may use subtyping to
formally restrict the set of possible values. An initial set of
commonly used derived types is defined in the SMIng standard module
NMRG-SMING [RFC3781].
The different base types and their derived types allow different
kinds of subtyping, namely size restrictions of octet strings
(Section 3.1), range restrictions of numeric types (Section 3.4
through Section 3.10), restricted pointer types (Section 3.2), and
restrictions on the sets of named numbers for enumeration types
(Section 3.11) and bit sets (Section 3.12).
3.1. OctetString
The OctetString base type represents arbitrary binary or textual
data. Although SMIng has a theoretical size limitation of 2^16-1
(65535) octets for this base type, module designers should realize
that there may be implementation and interoperability limitations for
sizes in excess of 255 octets.
Values of octet strings may be denoted as textual data enclosed in
double quotes or as arbitrary binary data denoted as a `0x'-prefixed
hexadecimal value of an even number of at least two hexadecimal
digits, where each pair of hexadecimal digits represents a single
octet. Letters in hexadecimal values MAY be upper-case, but lower-
case characters are RECOMMENDED. Textual data may contain any number
(possibly zero) of any 7-bit displayable ASCII characters, including
tab characters, spaces, and line terminator characters (nl or cr &
nl). Some characters require a special encoding (see Section 4.2).
Textual data may span multiple lines, where each subsequent line
prefix containing only white space up to the column where the first
line's data starts SHOULD be skipped by parsers for a better text
formatting.
When defining a type derived (directly or indirectly) from the
OctetString base type, the size in octets may be restricted by
appending a list of size ranges or explicit size values, separated by
pipe `|' characters, with the whole list enclosed in parenthesis. A
size range consists of a lower bound, two consecutive dots `..', and
an upper bound. Each value can be given in decimal or `0x'-prefixed
hexadecimal notation. Hexadecimal numbers must have an even number
of at least two digits. Size restricting values MUST NOT be
negative. If multiple values or ranges are given, they all MUST be
disjoint and MUST be in ascending order. If a size restriction is
applied to an already size restricted octet string, the new
restriction MUST be equal or more limiting, that is, raising the
lower bounds, reducing the upper bounds, removing explicit size
values or ranges, or splitting ranges into multiple ranges with
intermediate gaps.
Value Examples:
"This is a multiline
textual data example." // legal
"This is "illegally" quoted." // illegal quotes
"This is \"legally\" quoted." // legally encoded quotes
"But this is 'ok', as well." // legal apostrophe quoting
"" // legal zero length
0x123 // illegal odd hex length
0x534d496e670a // legal octet string
Restriction Examples:
OctetString (0 | 4..255) // legal size spec
OctetString (4) // legal exact size
OctetString (-1 | 1) // illegal negative size
OctetString (5 | 0) // illegal ordering
OctetString (1 | 1..10) // illegal overlapping
3.2. Pointer
The Pointer base type represents values that reference class
instances, attributes of class instances, or arbitrary identities.
The only values of the Pointer type that can be present in a module
can refer to identities. They are denoted as identifiers of the
concerned identities.
When defining a type derived (directly or indirectly) from the
Pointer base type, the values may be restricted to a specific class,
attribute or identity, and all (directly or indirectly) derived items
thereof by appending the identifier of the appropriate construct
enclosed in parenthesis.
Value Examples:
null // legal identity name
snmpUDPDomain // legal identity name
Restriction Examples:
Pointer (snmpTransportDomain) // legal restriction
3.3. ObjectIdentifier
The ObjectIdentifier base type represents administratively assigned
names for use with SNMP and COPS-PR. This type SHOULD NOT be used in
protocol independent SMIng modules. It is meant to be used in SNMP
and COPS-PR mappings of attributes of type Pointer (Section 3.2).
Values of this type may be denoted as a sequence of numerical non-
negative sub-identifier values in which each MUST NOT exceed 2^32-1
(4294967295). Sub-identifiers may be denoted in decimal or `0x'-
prefixed hexadecimal. They are separated by single dots and without
any intermediate white space. Alternatively (and preferred in most
cases), the first element may be a previously defined or imported
lower-case identifier, representing a static object identifier
prefix.
Although the number of sub-identifiers in SMIng object identifiers is
not limited, module designers should realize that there may be
implementations that stick with the SMIv1/v2 limit of 128 sub-
identifiers.
Object identifier derived types cannot be restricted in any way.
Value Examples:
1.3.6.1 // legal numerical oid
mib-2.1 // legal oid with identifier prefix
internet.4.1.0x0627.0x01 // legal oid with hex subids
iso.-1 // illegal negative subid
iso.org.6 // illegal non-heading identifier
IF-MIB::ifNumber.0 // legal fully qualified instance oid
3.4. Integer32
The Integer32 base type represents integer values between
-2^31 (-2147483648) and 2^31-1 (2147483647).
Values of type Integer32 may be denoted as decimal or hexadecimal
numbers, where only decimal numbers can be negative. Decimal numbers
other than zero MUST NOT have leading zero digits. Hexadecimal
numbers are prefixed by `0x' and MUST have an even number of at least
two hexadecimal digits, where letters MAY be upper-case, but lower-
case characters are RECOMMENDED.
When defining a type derived (directly or indirectly) from the
Integer32 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, and the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. Each value can be given in decimal or `0x'-prefixed
hexadecimal notation. Hexadecimal numbers must have an even number
of at least two digits. If multiple values or ranges are given they
all MUST be disjoint and MUST be in ascending order. If a value
restriction is applied to an already restricted type, the new
restriction MUST be equal or more limiting, that is raising the lower
bounds, reducing the upper bounds, removing explicit values or
ranges, or splitting ranges into multiple ranges with intermediate
gaps.
Value Examples:
015 // illegal leading zero
-123 // legal negative value
- 1 // illegal intermediate space
0xabc // illegal hexadecimal value length
-0xff // illegal sign on hex value
0x80000000 // illegal value, too large
0xf00f // legal hexadecimal value
Restriction Examples:
Integer32 (0 | 5..10) // legal range spec
Integer32 (5..10 | 2..3) // illegal ordering
Integer32 (4..8 | 5..10) // illegal overlapping
3.5. Integer64
The Integer64 base type represents integer values between
-2^63 (-9223372036854775808) and 2^63-1 (9223372036854775807).
Values of type Integer64 may be denoted as decimal or hexadecimal
numbers, where only decimal numbers can be negative. Decimal numbers
other than zero MUST NOT have leading zero digits. Hexadecimal
numbers are prefixed by `0x' and MUST have an even number of
hexadecimal digits, where letters MAY be upper-case, but lower-case
characters are RECOMMENDED.
When defining a type derived (directly or indirectly) from the
Integer64 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. Each value can be given in decimal or `0x'-prefixed
hexadecimal notation. Hexadecimal numbers must have an even number
of at least two digits. If multiple values or ranges are given, they
all MUST be disjoint and MUST be in ascending order. If a value
restriction is applied to an already restricted type, the new
restriction MUST be equal or more limiting, that is raising the lower
bounds, reducing the upper bounds, removing explicit values or
ranges, or splitting ranges into multiple ranges with intermediate
gaps.
Value Examples:
015 // illegal leading zero
-123 // legal negative value
- 1 // illegal intermediate space
0xabc // illegal hexadecimal value length
-0xff // illegal sign on hex value
0x80000000 // legal value
Restriction Examples:
Integer64 (0 | 5..10) // legal range spec
Integer64 (5..10 | 2..3) // illegal ordering
Integer64 (4..8 | 5..10) // illegal overlapping
3.6. Unsigned32
The Unsigned32 base type represents positive integer values between 0
and 2^32-1 (4294967295).
Values of type Unsigned32 may be denoted as decimal or hexadecimal
numbers. Decimal numbers other than zero MUST NOT have leading zero
digits. Hexadecimal numbers are prefixed by `0x' and MUST have an
even number of hexadecimal digits, where letters MAY be upper-case,
but lower-case characters are RECOMMENDED.
When defining a type derived (directly or indirectly) from the
Unsigned32 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. Each value can be given in decimal or `0x'-prefixed
hexadecimal notation. Hexadecimal numbers must have an even number
of at least two digits. If multiple values or ranges are given, they
all MUST be disjoint and MUST be in ascending order. If a value
restriction is applied to an already restricted type, the new
restriction MUST be equal or more limiting, that is raising the lower
bounds, reducing the upper bounds, removing explicit values or
ranges, or splitting ranges into multiple ranges with intermediate
gaps.
Value Examples:
015 // illegal leading zero
-123 // illegal negative value
0xabc // illegal hexadecimal value length
0x80000000 // legal hexadecimal value
0x8080000000 // illegal value, too large
Restriction Examples:
Unsigned32 (0 | 5..10) // legal range spec
Unsigned32 (5..10 | 2..3) // illegal ordering
Unsigned32 (4..8 | 5..10) // illegal overlapping
3.7. Unsigned64
The Unsigned64 base type represents positive integer values between 0
and 2^64-1 (18446744073709551615).
Values of type Unsigned64 may be denoted as decimal or hexadecimal
numbers. Decimal numbers other than zero MUST NOT have leading zero
digits. Hexadecimal numbers are prefixed by `0x' and MUST have an
even number of hexadecimal digits, where letters MAY be upper-case,
but lower-case characters are RECOMMENDED.
When defining a type derived (directly or indirectly) from the
Unsigned64 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. Each value can be given in decimal or `0x'-prefixed
hexadecimal notation. Hexadecimal numbers must have an even number
of at least two digits. If multiple values or ranges are given, they
all MUST be disjoint and MUST be in ascending order. If a value
restriction is applied to an already restricted type, the new
restriction MUST be equal or more limiting, that is raising the lower
bounds, reducing the upper bounds, removing explicit values or
ranges, or splitting ranges into multiple ranges with intermediate
gaps.
Value Examples:
015 // illegal leading zero
-123 // illegal negative value
0xabc // illegal hexadecimal value length
0x8080000000 // legal hexadecimal value
Restriction Examples:
Unsigned64 (1..10000000000) // legal range spec
Unsigned64 (5..10 | 2..3) // illegal ordering
3.8. Float32
The Float32 base type represents floating point values of single
precision as described by [IEEE754].
Values of type Float32 may be denoted as a decimal fraction with an
optional exponent, as known from many programming languages. See the
grammar rule `floatValue' of Appendix B for the detailed syntax.
Special values are `snan' (signalling Not-a-Number), `qnan' (quiet
Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
infinity). Note that -0.0 and +0.0 are different floating point
values. 0.0 is equal to +0.0.
When defining a type derived (directly or indirectly) from the
Float32 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. If multiple values or ranges are given, they all MUST be
disjoint and MUST be in ascending order. If a value restriction is
applied to an already restricted type, the new restriction MUST be
equal or more limiting, that is raising the lower bounds, reducing
the upper bounds, removing explicit values or ranges, or splitting
ranges into multiple ranges with intermediate gaps. The special
values `snan', `qnan', `neginf', and `posinf' must be explicitly
listed in restrictions if they shall be included, where `snan' and
`qnan' cannot be used in ranges.
Note that encoding is not subject to this specification. It has to
be described by protocols that transport objects of type Float32.
Note also that most floating point encodings disallow the
representation of many values that can be written as decimal
fractions as used in SMIng for human readability. Therefore,
explicit values in floating point type restrictions should be handled
with care.
Value Examples:
00.1 // illegal leading zero
3.1415 // legal value
-2.5E+3 // legal negative exponential value
Restriction Examples:
Float32 (-1.0..1.0) // legal range spec
Float32 (1 | 3.3 | 5) // legal, probably unrepresentable 3.3
Float32 (neginf..-0.0) // legal range spec
Float32 (-10.0..10.0 | 0) // illegal overlapping
3.9. Float64
The Float64 base type represents floating point values of double
precision as described by [IEEE754].
Values of type Float64 may be denoted as a decimal fraction with an
optional exponent, as known from many programming languages. See the
grammar rule `floatValue' of Appendix B for the detailed syntax.
Special values are `snan' (signalling Not-a-Number), `qnan' (quiet
Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
infinity). Note that -0.0 and +0.0 are different floating point
values. 0.0 is equal to +0.0.
When defining a type derived (directly or indirectly) from the
Float64 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. If multiple values or ranges are given, they all MUST be
disjoint and MUST be in ascending order. If a value restriction is
applied to an already restricted type, the new restriction MUST be
equal or more limiting, that is raising the lower bounds, reducing
the upper bounds, removing explicit values or ranges, or splitting
ranges into multiple ranges with intermediate gaps. The special
values `snan', `qnan', `neginf', and `posinf' must be explicitly
listed in restrictions if they shall be included, where `snan' and
`qnan' cannot be used in ranges.
Note that encoding is not subject to this specification. It has to
be described by protocols that transport objects of type Float64.
Note also that most floating point encodings disallow the
representation of many values that can be written as decimal
fractions as used in SMIng for human readability. Therefore,
explicit values in floating point type restrictions should be handled
with care.
Value Examples:
00.1 // illegal leading zero
3.1415 // legal value
-2.5E+3 // legal negative exponential value
Restriction Examples:
Float64 (-1.0..1.0) // legal range spec
Float64 (1 | 3.3 | 5) // legal, probably unrepresentable 3.3
Float64 (neginf..-0.0) // legal range spec
Float64 (-10.0..10.0 | 0) // illegal overlapping
3.10. Float128
The Float128 base type represents floating point values of quadruple
precision as described by [IEEE754].
Values of type Float128 may be denoted as a decimal fraction with an
optional exponent, as known from many programming languages. See the
grammar rule `floatValue' of Appendix B for the detailed syntax.
Special values are `snan' (signalling Not-a-Number), `qnan' (quiet
Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
infinity). Note that -0.0 and +0.0 are different floating point
values. 0.0 is equal to +0.0.
When defining a type derived (directly or indirectly) from the
Float128 base type, the set of possible values may be restricted by
appending a list of ranges or explicit values, separated by pipe `|'
characters, with the whole list enclosed in parenthesis. A range
consists of a lower bound, two consecutive dots `..', and an upper
bound. If multiple values or ranges are given, they all MUST be
disjoint and MUST be in ascending order. If a value restriction is
applied to an already restricted type, the new restriction MUST be
equal or more limiting, that is raising the lower bounds, reducing
the upper bounds, removing explicit values or ranges, or splitting
ranges into multiple ranges with intermediate gaps. The special
values `snan', `qnan', `neginf', and `posinf' must be explicitly
listed in restrictions if they shall be included, where `snan' and
`qnan' cannot be used in ranges.
Note that encoding is not subject to this specification. It has to
be described by protocols that transport objects of type Float128.
Note also that most floating point encodings disallow the
representation of many values that can be written as decimal
fractions as used in SMIng for human readability. Therefore,
explicit values in floating point type restrictions should be handled
with care.
Value Examples:
00.1 // illegal leading zero
3.1415 // legal value
-2.5E+3 // legal negative exponential value
Restriction Examples:
Float128 (-1.0..1.0) // legal range spec
Float128 (1 | 3.3 | 5) // legal, probably unrepresentable 3.3
Float128 (neginf..-0.0) // legal range spec
Float128 (-10.0..10.0 | 0) // illegal overlapping
3.11. Enumeration
The Enumeration base type represents values from a set of integers in
the range between -2^31 (-2147483648) and 2^31-1 (2147483647), where
each value has an assigned name. The list of those named numbers has
to be comma-separated, enclosed in parenthesis, and appended to the
`Enumeration' keyword. Each named number is denoted by its lower-
case identifier followed by the assigned integer value, denoted as a
decimal or `0x'-prefixed hexadecimal number, enclosed in parenthesis.
Hexadecimal numbers must have an even number of at least two digits.
Every name and every number in an enumeration type MUST be unique.
It is RECOMMENDED that values be positive, start at 1, and be
numbered contiguously. All named numbers MUST be given in ascending
order.
Values of enumeration types may be denoted as decimal or `0x'-
prefixed hexadecimal numbers or preferably as their assigned names.
Hexadecimal numbers must have an even number of at least two digits.
When types are derived (directly or indirectly) from an enumeration
type, the set of named numbers may be equal or restricted by removing
one or more named numbers, but no named numbers may be added or
changed regarding its name, value, or both.
Type and Value Examples:
Enumeration (up(1), down(2), testing(3))
Enumeration (down(2), up(1)) // illegal order
0 // legal (though not recommended) value
up // legal value given by name
2 // legal value given by number
3.12. Bits
The Bits base type represents bit sets. That is, a Bits value is a
set of flags identified by small integer numbers starting at 0. Each
bit number has an assigned name. The list of those named numbers has
to be comma-separated, enclosed in parenthesis, and appended to the
`Bits' keyword. Each named number is denoted by its lower-case
identifier followed by the assigned integer value, denoted as a
decimal or `0x'-prefixed hexadecimal number, enclosed in parenthesis.
Hexadecimal numbers must have an even number of at least two digits.
Every name and every number in a bits type MUST be unique. It is
RECOMMENDED that numbers start at 0 and be numbered contiguously.
Negative numbers are forbidden. All named numbers MUST be given in
ascending order.
Values of bits types may be denoted as a comma-separated list of
decimal or `0x'-prefixed hexadecimal numbers or preferably their
assigned names enclosed in parenthesis. Hexadecimal numbers must
have an even number of at least two digits. There MUST NOT be any
element (by name or number) listed more than once. Elements MUST be
listed in ascending order.
When defining a type derived (directly or indirectly) from a bits
type, the set of named numbers may be restricted by removing one or
more named numbers, but no named numbers may be added or changed
regarding its name, value, or both.
Type and Value Examples:
Bits (readable(0), writable(1), executable(2))
Bits (writable(1), readable(0) // illegal order
() // legal empty value
(readable, writable, 2) // legal value
(0, readable, executable) // illegal, readable(0) appears twice
(writable, 4) // illegal, element 4 out of range
3.13. Display Formats
Attribute and type definitions allow the specification of a format to
be used when a value of that attribute or an attribute of that type
is displayed. Format specifications are represented as textual data.
When the attribute or type has an underlying base type of Integer32,
Integer64, Unsigned32, or Unsigned64, the format consists of an
integer-format specification containing two parts. The first part is
a single character suggesting a display format, either: `x' for
hexadecimal, `d' for decimal, `o' for octal, or `b' for binary. For
all types, when rendering the value, leading zeros are omitted, and
for negative values, a minus sign is rendered immediately before the
digits. The second part is always omitted for `x', `o', and `b', and
need not be present for `d'. If present, the second part starts with
a hyphen and is followed by a decimal number, which defines the
implied decimal point when rendering the value. For example `d-2'
suggests that a value of 1234 be rendered as `12.34'.
When the attribute or type has an underlying base type of
OctetString, the format consists of one or more octet-format
specifications. Each specification consists of five parts, with each
part using and removing zero or more of the next octets from the
value and producing the next zero or more characters to be displayed.
The octets within the value are processed in order of significance,
most significant first.
The five parts of a octet-format specification are:
1. The (optional) repeat indicator. If present, this part is a `*',
and indicates that the current octet of the value is to be used as
the repeat count. The repeat count is an unsigned integer (which
may be zero) specifying how many times the remainder of this
octet-format specification should be successively applied. If the
repeat indicator is not present, the repeat count is one.
2. The octet length: one or more decimal digits specifying the number
of octets of the value to be used and formatted by this octet-
specification. Note that the octet length can be zero. If less
than this number of octets remain in the value, then the lesser
number of octets are used.
3. The display format, either: `x' for hexadecimal, `d' for decimal,
`o' for octal, `a' for ASCII, or `t' for UTF-8 [RFC3629]. If the
octet length part is greater than one, and the display format part
refers to a numeric format, then network byte-ordering (big-endian
encoding) is used to interpret the octets in the value. The
octets processed by the `t' display format do not necessarily form
an integral number of UTF-8 characters. Trailing octets which do
not form a valid UTF-8 encoded character are discarded.
4. The (optional) display separator character. If present, this part
is a single character produced for display after each application
of this octet-specification; however, this character is not
produced for display if it would be immediately followed by the
display of the repeat terminator character for this octet
specification. This character can be any character other than a
decimal digit and a `*'.
5. The (optional) repeat terminator character, which can be present
only if the display separator character is present and this octet
specification begins with a repeat indicator. If present, this
part is a single character produced after all the zero or more
repeated applications (as given by the repeat count) of this octet
specification. This character can be any character other than a
decimal digit and a `*'.
Output of a display separator character or a repeat terminator
character is suppressed if it would occur as the last character of
the display.
If the octets of the value are exhausted before all the octet format
specifications have been used, then the excess specifications are
ignored. If additional octets remain in the value after interpreting
all the octet format specifications, then the last octet format
specification is re-interpreted to process the additional octets,
until no octets remain in the value.
Note that for some types, no format specifications are defined. For
derived types and attributes that are based on such types, format
specifications SHOULD be omitted. Implementations MUST ignore format
specifications they cannot interpret. Also note that the SMIng
grammar (Appendix B) does not specify the syntax of format
specifications.
Display Format Examples:
Base Type Format Example Value Rendered Value
----------- ------------------- ---------------- -----------------
OctetString 255a "Hello World." Hello World.
OctetString 1x: "Hello!" 48:65:6c:6c:6f:21
OctetString 1d:1d:1d.1d,1a1d:1d 0x0d1e0f002d0400 13:30:15.0,-4:0
OctetString 1d.1d.1d.1d/2d 0x0a0000010400 10.0.0.1/1024
OctetString *1x:/1x: 0x02aabbccddee aa:bb/cc:dd:ee
Integer32 d-2 1234 12.34
4. The SMIng File Structure
The topmost container of SMIng information is a file. An SMIng file
may contain zero, one or more modules. It is RECOMMENDED that
modules be stored into separate files by their module names, where
possible. However, for dedicated purposes, it may be reasonable to
collect several modules in a single file.
The top level SMIng construct is the `module' statement (Section 5)
that defines a single SMIng module. A module contains a sequence of
sections in an obligatory order with different kinds of definitions.
Whether these sections contain statements or remain empty mainly
depends on the purpose of the module.
4.1. Comments
Comments can be included at any position in an SMIng file, except
between the characters of a single token like those of a quoted
string. However, it is RECOMMENDED that all substantive descriptions
be placed within an appropriate description clause, so that the
information is available to SMIng parsers.
Comments commence with a pair of adjacent slashes `//' and end at the
end of the line.
4.2. Textual Data
Some statements, namely `organization', `contact', `description',
`reference', `abnf', `format', and `units', get a textual argument.
This text, as well as representations of OctetString values, have to
be enclosed in double quotes. They may contain arbitrary characters
with the following exceptional encoding rules:
A backslash character introduces a special character, which depends
on the character that immediately follows the backslash:
\n new line
\t a tab character
\" a double quote
\\ a single backslash
If the text contains a line break followed by whitespace which is
used to indent the text according to the layout in the SMIng file,
this prefixing whitespace is stripped from the text.
4.3. Statements and Arguments
SMIng has a very small set of basic grammar rules based on the
concept of statements. Each statement starts with a lower-case
keyword identifying the statement, followed by a number (possibly
zero) of arguments. An argument may be quoted text, an identifier, a
value of any base type, a list of identifiers enclosed in parenthesis
`( )', or a statement block enclosed in curly braces `{ }'. Since
statement blocks are valid arguments, it is possible to nest
statement sequences. Each statement is terminated by a semicolon
`;'.
The core set of statements may be extended using the SMIng
`extension' statement. See Sections 6 and 11 for details.
At places where a statement is expected, but an unknown lower-case
word is read, those statements MUST be skipped up to the proper
semicolon, including nested statement blocks.
5. The module Statement
The `module' statement is used as a container of all definitions of a
single SMIng module. It gets two arguments: an upper-case module
name and a statement block that contains mandatory and optional
statements and sections of statements in an obligatory order:
module <MODULE-NAME> {
<optional import statements>
<organization statement>
<contact statement>
<description statement>
<optional reference statement>
<at least one revision statement>
<optional extension statements>
<optional typedef statements>
<optional identity statements>
<optional class statements>
};
The optional `import' statements (Section 5.1) are followed by the
mandatory `organization' (Section 5.2), `contact' (Section 5.3), and
`description' (Section 5.4) statements and the optional `reference'
statement (Section 5.5), which in turn are followed by at least one
mandatory `revision' statement (Section 5.6). The part up to this
point defines the module's meta information, i.e., information that
describes the whole module but does not define any items used by
applications in the first instance. This part of a module is
followed by its main definitions, namely SMIng extensions (Section
6), derived types (Section 7), identities (Section 8), and classes
(Section 9).
See the `moduleStatement' rule of the SMIng grammar (Appendix B) for
the formal syntax of the `module' statement.
5.1. The module's import Statement
The optional module's `import' statement is used to import
identifiers from external modules into the local module's namespace.
It gets two arguments: the name of the external module and a comma-
separated list of one or more identifiers to be imported enclosed in
parenthesis.
Multiple `import' statements for the same module but with disjoint
lists of identifiers are allowed, though NOT RECOMMENDED. The same
identifier from the same module MUST NOT be imported multiple times.
To import identifiers with the same name from different modules might
be necessary and is allowed. To distinguish
them in the local module, they have to be referred by qualified
names. Importing identifiers not used in the local module is NOT
RECOMMENDED.
See the `importStatement' rule of the SMIng grammar (Appendix B) for
the formal syntax of the `import' statement.
5.2. The module's organization Statement
The module's `organization' statement, which must be present, gets
one argument which is used to specify a textual description of the
organization(s) under whose auspices this module was developed.
5.3. The module's contact Statement
The module's `contact' statement, which must be present, gets one
argument which is used to specify the name, postal address, telephone
number, and electronic mail address of the person to whom technical
queries concerning this module should be sent.
5.4. The module's description Statement
The module's `description' statement, which must be present, gets one
argument which is used to specify a high-level textual description of
the contents of this module.
5.5. The module's reference Statement
The module's `reference' statement, which need not be present, gets
one argument which is used to specify a textual cross-reference to
some other document, either another module which defines related
management information, or some other document which provides
additional information relevant to this module.
5.6. The module's revision Statement
The module's `revision' statement is repeatedly used to specify the
editorial revisions of the module, including the initial revision.
It gets one argument which is a statement block that holds detailed
information in an obligatory order. A module MUST have at least one
initial `revision' statement. For every editorial change, a new one
MUST be added in front of the revisions sequence, so that all
revisions are in reverse chronological order.
See the `revisionStatement' rule of the SMIng grammar (Appendix B)
for the formal syntax of the `revision' statement.
5.6.1. The revision's date Statement
The revision's `date' statement, which must be present, gets one
argument which is used to specify the date and time of the revision
in the format `YYYY-MM-DD HH:MM' or `YYYY-MM-DD' which implies the
time `00:00'. The time is always given in UTC.
See the `date' rule of the SMIng grammar (Appendix B) for the formal
syntax of the revision's `date' statement.
5.6.2. The revision's description Statement
The revision's `description' statement, which must be present, gets
one argument which is used to specify a high-level textual
description of the revision.
5.7. Usage Example
Consider how a skeletal module might be constructed:
module ACME-MIB {
import NMRG-SMING (DisplayString);
organization
"IRTF Network Management Research Group (NMRG)";
contact "IRTF Network Management Research Group (NMRG)
http://www.ibr.cs.tu-bs.de/projects/nmrg/
Joe L. User
ACME, Inc.
42 Anywhere Drive
Nowhere, CA 95134
USA
Phone: +1 800 555 0815
EMail: joe@acme.example.com";
description
"The module for entities implementing the ACME protocol.
Copyright (C) The Internet Society (2004).
All Rights Reserved.
This version of this MIB module is part of RFC 3780,
see the RFC itself for legal notices.";
revision {
date "2003-12-16";
description
"Initial revision, published as RFC 3780.";
};
// ... further definitions ...
}; // end of module ACME-MIB.
6. The extension Statement
The `extension' statement defines new statements to be used in the
local module following this extension statement definition or in
external modules that may import this extension statement definition.
The `extension' statement gets two arguments: a lower-case extension
statement identifier and a statement block that holds detailed
extension information in an obligatory order.
Extension statement identifiers SHOULD NOT contain any upper-case
characters.
Note that the SMIng extension feature does not allow the formal
specification of the context, or argument syntax and semantics of an
extension. Its only purpose is to declare the existence of an
extension and to allow a unique reference to an extension. See
Section 11 for detailed information on extensions and [RFC3781] for
mappings of SMIng definitions to SNMP, which is formally defined as
an extension.
See the `extensionStatement' rule of the SMIng grammar (Appendix B)
for the formal syntax of the `extension' statement.
6.1. The extension's status Statement
The extension's `status' statement, which must be present, gets one
argument which is used to specify whether this extension definition
is current or historic. The value `current' means that the
definition is current and valid. The value `obsolete' means the
definition is obsolete and should not be implemented and/or can be
removed if previously implemented. While the value `deprecated' also
indicates an obsolete definition, it permits new/continued
implementation in order to foster interoperability with older/
existing implementations.
6.2. The extension's description Statement
The extension's `description' statement, which must be present, gets
one argument which is used to specify a high-level textual
description of the extension statement.
It is RECOMMENDED that information on the extension's context, its
semantics, and implementation conditions be included. See also
Section 11.
6.3. The extension's reference Statement
The extension's `reference' statement, which need not be present,
gets one argument which is used to specify a textual cross-reference
to some other document, either another module which defines related
extension definitions, or some other document which provides
additional information relevant to this extension.
6.4. The extension's abnf Statement
The extension's `abnf' statement, which need not be present, gets one
argument which is used to specify a formal ABNF [RFC2234] grammar
definition of the extension. This grammar can reference rule names
from the core SMIng grammar (Appendix B).
Note that the `abnf' statement should contain only pure ABNF and no
additional text, though comments prefixed by a semicolon are allowed
but should probably be moved to the description statement. Note that
double quotes within the ABNF grammar have to be represented as `\"'
according to Section 4.2.
6.5. Usage Example
extension severity {
status current;
description
"The optional severity extension statement can only
be applied to the statement block of an SMIng class'
event definition. If it is present it denotes the
severity level of the event in a range from 0
(emergency) to 7 (debug).";
abnf
"severityStatement = severityKeyword sep number optsep \";\"
severityKeyword = \"severity\"";
};
7. The typedef Statement
The `typedef' statement defines new data types to be used in the
local module or in external modules. It gets two arguments: an
upper-case type identifier and a statement block that holds detailed
type information in an obligatory order.
Type identifiers SHOULD NOT consist of all upper-case characters and
SHOULD NOT contain hyphens.
See the `typedefStatement' rule of the SMIng grammar (Appendix B) for
the formal syntax of the `typedef' statement.
7.1. The typedef's type Statement
The typedef's `type' statement, which must be present, gets one
argument which is used to specify the type from which this type is
derived. Optionally, type restrictions may be applied to the new
type by appending subtyping information according to the rules of the
base type. See Section 3 for SMIng base types and their type
restrictions.
7.2. The typedef's default Statement
The typedef's `default' statement, which need not be present, gets
one argument which is used to specify an acceptable default value for
attributes of this type. A default value may be used when an
attribute instance is created. That is, the value is a "hint" to
implementors.
The value of the `default' statement must, of course, correspond to
the (probably restricted) type specified in the typedef's `type'
statement.
The default value of a type may be overwritten by a default value of
an attribute of this type.
Note that for some types, default values make no sense.
7.3. The typedef's format Statement
The typedef's `format' statement, which need not be present, gets one
argument which is used to give a hint as to how the value of an
instance of an attribute of this type might be displayed. See
Section 3.13 for a description of format specifications.
If no format is specified, it is inherited from the type given in the
`type' statement. On the other hand, the format specification of a
type may be semantically refined by a format specification of an
attribute of this type.
7.4. The typedef's units Statement
The typedef's `units' statement, which need not be present, gets one
argument which is used to specify a textual definition of the units
associated with attributes of this type.
If no units are specified, they are inherited from the type given in
the `type' statement. On the other hand, the units specification of
a type may be semantically refined by a units specification of an
attribute of this type.
The units specification has to be appropriate for values displayed
according to the typedef's format specification, if present. For
example, if the type defines frequency values of type Unsigned64
measured in thousands of Hertz, the format specification should be
`d-3' and the units specification should be `Hertz' or `Hz'. If the
format specification would be omitted, the units specification should
be `Milli-Hertz' or `mHz'. Authors of SMIng modules should pay
attention to keep format and units specifications in sync.
Application implementors MUST NOT implement units specifications
without implementing format specifications.
7.5. The typedef's status Statement
The typedef's `status' statement, which must be present, gets one
argument which is used to specify whether this type definition is
current or historic. The value `current' means that the definition
is current and valid. The value `obsolete' means the definition is
obsolete and should not be implemented and/or can be removed if
previously implemented. While the value `deprecated' also indicates
an obsolete definition, it permits new/continued implementation in
order to foster interoperability with older/existing implementations.
Derived types SHOULD NOT be defined as `current' if their underlying
type is `deprecated' or `obsolete'. Similarly, they SHOULD NOT be
defined as `deprecated' if their underlying type is `obsolete'.
Nevertheless, subsequent revisions of the underlying type cannot be
avoided, but SHOULD be taken into account in subsequent revisions of
the local module.
7.6. The typedef's description Statement
The typedef's `description' statement, which must be present, gets
one argument which is used to specify a high-level textual
description of the newly defined type.
It is RECOMMENDED that all semantic definitions necessary for
implementation, and to embody any information which would otherwise
be communicated in any commentary annotations associated with this
type definition be included.
7.7. The typedef's reference Statement
The typedef's `reference' statement, which need not be present, gets
one argument which is used to specify a textual cross-reference to
some other document, either another module which defines related type
definitions, or some other document which provides additional
information relevant to this type definition.
7.8. Usage Examples
typedef RptrOperStatus {
type Enumeration (other(1), ok(2), rptrFailure(3),
groupFailure(4), portFailure(5),
generalFailure(6));
default other; // undefined by default.
status deprecated;
description
"A type to indicate the operational state
of a repeater.";
reference
"[IEEE 802.3 Mgt], 30.4.1.1.5, aRepeaterHealthState.";
};
typedef SnmpTransportDomain {
type Pointer (snmpTransportDomain);
status current;
description
"A pointer to an SNMP transport domain identity.";
};
typedef DateAndTime {
type OctetString (8 | 11);
format "2d-1d-1d,1d:1d:1d.1d,1a1d:1d";
status current;
description
"A date-time specification.
...
Note that if only local time is known, then timezone
information (fields 8-10) is not present.";
reference
"RFC 2579, SNMPv2-TC.DateAndTime.";
};
typedef Frequency {
type Unsigned64;
format "d-3"
units "Hertz";
status current;
description
"A wide-range frequency specification measured
in thousands of Hertz.";
};
8. The identity Statement
The `identity' statement is used to define a new abstract and untyped
identity. Its only purpose is to denote its name, semantics, and
existence. An identity can be defined either from scratch or derived
from a parent identity. The `identity' statement gets the following
two arguments: The first argument is a lower-case identity
identifier. The second argument is a statement block that holds
detailed identity information in an obligatory order.
See the `identityStatement' rule of the SMIng grammar (Appendix B)
for the formal syntax of the `identity' statement.
8.1. The identity's parent Statement
The identity's `parent' statement must be present for a derived
identity and must be absent for an identity defined from scratch. It
gets one argument which is used to specify the parent identity from
which this identity shall be derived.
8.2. The identity's status Statement
The identity's `status' statement, which must be present, gets one
argument which is used to specify whether this identity definition is
current or historic. The value `current' means that the definition
is current and valid. The value `obsolete' means the definition is
obsolete and should not be implemented and/or can be removed if
previously implemented. While the value `deprecated' also indicates
an obsolete definition, it permits new/continued implementation in
order to foster interoperability with older/existing implementations.
Derived identities SHOULD NOT be defined as `current' if their parent
identity is `deprecated' or `obsolete'. Similarly, they SHOULD NOT
be defined as `deprecated' if their parent identity is `obsolete'.
Nevertheless, subsequent revisions of the parent identity cannot be
avoided, but SHOULD be taken into account in subsequent revisions of
the local module.
8.3. The identity' description Statement
The identity's `description' statement, which must be present, gets
one argument which is used to specify a high-level textual
description of the newly defined identity.
It is RECOMMENDED that all semantic definitions necessary for
implementation, and to embody any information which would otherwise
be communicated in any commentary annotations associated with this
identity definition be included.
8.4. The identity's reference Statement
The identity's `reference' statement, which need not be present, gets
one argument which is used to specify a textual cross-reference to
some other document, either another module which defines related
identity definitions, or some other document which provides
additional information relevant to this identity definition.
8.5. Usage Examples
identity null {
status current;
description
"An identity used to represent null pointer values.";
};
identity snmpTransportDomain {
status current;
description
"A generic SNMP transport domain identity.";
};
identity snmpUDPDomain {
parent snmpTransportDomain;
status current;
description
"The SNMP over UDP transport domain.";
};
9. The class Statement
The `class' statement is used to define a new class that represents a
container of related attributes and events (Section 9.2, Section
9.4). A class can be defined either from scratch or derived from a
parent class. A derived class inherits all attributes and events of
the parent class and can be extended by additional attributes and
events.
The `class' statement gets the following two arguments: The first
argument is an upper-case class identifier. The second argument is a
statement block that holds detailed class information in an
obligatory order.
See the `classStatement' rule of the SMIng grammar (Appendix B) for
the formal syntax of the `class' statement.
9.1. The class' extends Statement
The class' `extends' statement must be present for a class derived
from a parent class and must be absent for a class defined from
scratch. It gets one argument which is used to specify the parent
class from which this class shall be derived.
9.2. The class' attribute Statement
The class' `attribute' statement, which can be present zero, one or
multiple times, gets two arguments: the attribute name and a
statement block that holds detailed attribute information in an
obligatory order.
9.2.1. The attribute's type Statement
The attribute's `type' statement must be present. It gets at least
one argument which is used to specify the type of the attribute:
either a type name or a class name. In case of a type name, it may
be restricted by a second argument according to the restriction rules
described in Section 3.
9.2.2. The attribute's access Statement
The attribute's `access' statement must be present for attributes
typed by a base type or derived type, and must be absent for
attributes typed by a class. It gets one argument which is used to
specify whether it makes sense to read and/or write an instance of
the attribute, or to include its value in an event. This is the
maximal level of access for the attribute. This maximal level of
access is independent of any administrative authorization policy.
The value `readwrite' indicates that read and write access makes
sense. The value `readonly' indicates that read access makes sense,
but write access is never possible. The value `eventonly' indicates
an object which is accessible only via an event.
These values are ordered, from least to greatest access level:
`eventonly', `readonly', `readwrite'.
9.2.3. The attribute's default Statement
The attribute's `default' statement need not be present for
attributes typed by a base type or derived type, and must be absent
for attributes typed by a class. It gets one argument which is used
to specify an acceptable default value for this attribute. A default
value may be used when an attribute instance is created. That is,
the value is a "hint" to implementors.
The value of the `default' statement must, of course, correspond to
the (probably restricted) type specified in the attribute's `type'
statement.
The attribute's default value overrides the default value of the
underlying type definition if both are present.
9.2.4. The attribute's format Statement
The attribute's `format' statement need not be present for attributes
typed by a base type or derived type, and must be absent for
attributes typed by a class. It gets one argument which is used to
give a hint as to how the value of an instance of this attribute
might be displayed. See Section 3.13 for a description of format
specifications.
The attribute's format specification overrides the format
specification of the underlying type definition if both are present.
9.2.5. The attribute's units Statement
The attribute's `units' statement need not be present for attributes
typed by a base type or derived type, and must be absent for
attributes typed by a class. It gets one argument which is used to
specify a textual definition of the units associated with this
attribute.
The attribute's units specification overrides the units specification
of the underlying type definition if both are present.
The units specification has to be appropriate for values displayed
according to the attribute's format specification if present. For
example, if the attribute represents a frequency value of type
Unsigned64 measured in thousands of Hertz, the format specification
should be `d-3' and the units specification should be `Hertz' or
`Hz'. If the format specification would be omitted, the units
specification should be `Milli-Hertz' or `mHz'. Authors of SMIng
modules should pay attention to keep format and units specifications
of type and attribute definitions in sync. Application implementors
MUST NOT implement units specifications without implementing format
specifications.
9.2.6. The attribute's status Statement
The attribute's `status' statement must be present. It gets one
argument which is used to specify whether this attribute definition
is current or historic. The value `current' means that the
definition is current and valid. The value `obsolete' means the
definition is obsolete and should not be implemented and/or can be
removed if previously implemented. While the value `deprecated' also
indicates an obsolete definition, it permits new/continued
implementation in order to foster interoperability with older/
existing implementations.
Attributes SHOULD NOT be defined as `current' if their type or their
containing class is `deprecated' or `obsolete'. Similarly, they
SHOULD NOT be defined as `deprecated' if their type or their
containing class is `obsolete'. Nevertheless, subsequent revisions
of used type definition cannot be avoided, but SHOULD be taken into
account in subsequent revisions of the local module.
9.2.7. The attribute's description Statement
The attribute's `description' statement, which must be present, gets
one argument which is used to specify a high-level textual
description of this attribute.
It is RECOMMENDED that all semantic definitions necessary for the
implementation of this attribute be included.
9.2.8. The attribute's reference Statement
The attribute's `reference' statement, which need not be present,
gets one argument which is used to specify a textual cross-reference
to some other document, either another module which defines related
attribute definitions, or some other document which provides
additional information relevant to this attribute definition.
9.3. The class' unique Statement
The class' `unique' statement, which need not be present, gets one
argument that specifies a comma-separated list of attributes of this
class, enclosed in parenthesis. If present, this list of attributes
makes up a unique identification of all possible instances of this
class. It can be used as a unique key in underlying protocols.
If the list is empty, the class should be regarded as a scalar class
with only a single instance.
If the `unique' statement is not present, the class is not meant to
be instantiated directly, but to be contained in other classes or the
parent class of other refining classes.
If present, the attribute list MUST NOT contain any attribute more
than once and the attributes should be ordered where appropriate so
that the attributes that are most significant in most situations
appear first.
9.4. The class' event Statement
The class' `event' statement is used to define an event related to an
instance of this class that can occur asynchronously. It gets two
arguments: a lower-case event identifier and a statement block that
holds detailed information in an obligatory order.
See the `eventStatement' rule of the SMIng grammar (Appendix B) for
the formal syntax of the `event' statement.
9.4.1. The event's status Statement
The event's `status' statement, which must be present, gets one
argument which is used to specify whether this event definition is
current or historic. The value `current' means that the definition
is current and valid. The value `obsolete' means the definition is
obsolete and should not be implemented and/or can be removed if
previously implemented. While the value `deprecated' also indicates
an obsolete definition, it permits new/continued implementation in
order to foster interoperability with older/existing implementations.
9.4.2. The event's description Statement
The event's `description' statement, which must be present, gets one
argument which is used to specify a high-level textual description of
this event.
It is RECOMMENDED that all semantic definitions necessary for the
implementation of this event be included. In particular, which
instance of the class is associated with an event of this type SHOULD
be documented.
9.4.3. The event's reference Statement
The event's `reference' statement, which need not be present, gets
one argument which is used to specify a textual cross-reference to
some other document, either another module which defines related
event definitions, or some other document which provides additional
information relevant to this event definition.
9.5. The class' status Statement
The class' `status' statement, which must be present, gets one
argument which is used to specify whether this class definition is
current or historic. The value `current' means that the definition
is current and valid. The value `obsolete' means the definition is
obsolete and should not be implemented and/or can be removed if
previously implemented. While the value `deprecated' also indicates
an obsolete definition, it permits new/continued implementation in
order to foster interoperability with older/existing implementations.
Derived classes SHOULD NOT be defined as `current' if their parent
class is `deprecated' or `obsolete'. Similarly, they SHOULD NOT be
defined as `deprecated' if their parent class is `obsolete'.
Nevertheless, subsequent revisions of the parent class cannot be
avoided, but SHOULD be taken into account in subsequent revisions of
the local module.
9.6. The class' description Statement
The class' `description' statement, which must be present, gets one
argument which is used to specify a high-level textual description of
the newly defined class.
It is RECOMMENDED that all semantic definitions necessary for
implementation, and to embody any information which would otherwise
be communicated in any commentary annotations associated with this
class definition be included.
9.7. The class' reference Statement
The class' `reference' statement, which need not be present, gets one
argument which is used to specify a textual cross-reference to some
other document, either another module which defines related class
definitions, or some other document which provides additional
information relevant to this class definition.
9.8. Usage Example
Consider how an event might be described that signals a status change
of an interface:
class Interface {
// ...
attribute speed {
type Gauge32;
access readonly;
units "bps";
status current;
description
"An estimate of the interface's current bandwidth
in bits per second.";
};
// ...
attribute adminStatus {
type AdminStatus;
access readwrite;
status current;
description
"The desired state of the interface.";
};
attribute operStatus {
type OperStatus;
access readonly;
status current;
description
"The current operational state of the interface.";
};
event linkDown {
status current;
description
"A linkDown event signifies that the ifOperStatus
attribute for this interface instance is about to
enter the down state from some other state (but not
from the notPresent state). This other state is
indicated by the included value of ifOperStatus.";
};
status current;
description
"A physical or logical network interface.";
};
10. Extending a Module
As experience is gained with a module, it may be desirable to revise
that module. However, changes are not allowed if they have any
potential to cause interoperability problems between an
implementation using an original specification and an implementation
using an updated specification(s).
For any change, some statements near the top of the module MUST be
updated to include information about the revision: specifically, a
new `revision' statement (Section 5.6) must be included in front of
the `revision' statements. Furthermore, any necessary changes MUST
be applied to other statements, including the `organization' and
`contact' statements (Section 5.2, Section 5.3).
Note that any definition contained in a module is available to be
imported by any other module, and is referenced in an `import'
statement via the module name. Thus, a module name MUST NOT be
changed. Specifically, the module name (e.g., `ACME-MIB' in the
example of Section 5.7) MUST NOT be changed when revising a module
(except to correct typographical errors), and definitions MUST NOT be
moved from one module to another.
Also note that obsolete definitions MUST NOT be removed from modules
since their identifiers may still be referenced by other modules.
A definition may be revised in any of the following ways:
o In `typedef' statement blocks, a `type' statement containing an
`Enumeration' or `Bits' type may have new named numbers added.
o In `typedef' statement blocks, the value of a `type' statement may
be replaced by another type if the new type is derived (directly
or indirectly) from the same base type, has the same set of
values, and has identical semantics.
o In `attribute' statements where the `type' sub-statement specifies
a class, the class may be replaced by another class if the new
class is derived (directly or indirectly) from the base class and
both classes have identical semantics.
o In `attribute' statements where the `type' sub-statement specifies
a base type, a defined type, or an implicitly derived type (i.e.,
not a class), that type may be replaced by another type if the new
type is derived (directly or indirectly) from the same base type,
has the same set of values, and has identical semantics.
o In any statement block, a `status' statement value of `current'
may be revised as `deprecated' or `obsolete'. Similarly, a
`status' statement value of `deprecated' may be revised as
`obsolete'. When making such a change, the `description'
statement SHOULD be updated to explain the rationale.
o In `typedef' and `attribute' statement blocks, a `default'
statement may be added or updated.
o In `typedef' and `attribute' statement blocks, a `units' statement
may be added.
o A class may be augmented by adding new attributes.
o In any statement block, clarifications and additional information
may be included in the `description' statement.
o In any statement block, a `reference' statement may be added or
updated.
o Entirely new extensions, types, identities, and classes may be
defined, using previously unassigned identifiers.
Otherwise, if the semantics of any previous definition are changed
(i.e., if a non-editorial change is made to any definition other than
those specifically allowed above), then this MUST be achieved by a
new definition with a new identifier. In case of a class where the
semantics of any attributes are changed, the new class can be defined
by derivation from the old class and refining the changed attributes.
Note that changing the identifier associated with an existing
definition is considered a semantic change, as these strings may be
used in an `import' statement.
11. SMIng Language Extensibility
While the core SMIng language has a well defined set of statements
(Section 5 through Section 9.4) that are used to specify those
aspects of management information commonly regarded as necessary
without management protocol specific information, there may be
further information people wish to express. Describing additional
information informally in description statements has a disadvantage
in that this information cannot be parsed by any program.
SMIng allows modules to include statements that are unknown to a
parser but fulfil some core grammar rules (Section 4.3).
Furthermore, additional statements may be defined by the `extension'
statement (Section 6). Extensions can be used in the local module or
in other modules that import the extension. This has some
advantages:
o A parser can differentiate between statements known as extensions
and unknown statements. This enables the parser to complain about
unknown statements, e.g., due to typos.
o If an extension's definition contains a formal ABNF grammar
definition and a parser is able to interpret this ABNF definition,
this enables the parser to also complain about the wrong usage of
an extension.
o Since there might be some common need for extensions, there is a
relatively high probability of extension name collisions
originated by different organizations, as long as there is no
standardized extension for that purpose. The requirement to
explicitly import extension statements allows those extensions to
be distinguished.
o The supported extensions of an SMIng implementation, e.g., an
SMIng module compiler, can be clearly expressed.
The only formal effect of an extension statement definition is to
declare its existence and status, and optionally its ABNF grammar.
All additional aspects SHOULD be described in the `description'
statement:
o The detailed semantics of the new statement SHOULD be described.
o The contexts in which the new statement can be used SHOULD be
described, e.g., a new statement may be designed to be used only
in the statement block of a module, but not in other nested
statement blocks. Others may be applicable in multiple contexts.
In addition, the point in the sequence of an obligatory order of
other statements, where the new statement may be inserted, might
be prescribed.
o The circumstances that make the new statement mandatory or
optional SHOULD be described.
o The syntax of the new statement SHOULD at least be described
informally, if not supplied formally in an `abnf' statement.
o It might be reasonable to give some suggestions under which
conditions the implementation of the new statement is adequate and
how it could be integrated into existent implementations.
Some possible extension applications are:
o The formal mapping of SMIng definitions into the SNMP [RFC3781]
framework is defined as an SMIng extension. Other mappings may
follow in the future.
o Inlined annotations to definitions. For example, a vendor may
wish to describe additional information to class and attribute
definitions in private modules. An example are severity levels of
events in the statement block of an `event' statement.
o Arbitrary annotations to external definitions. For example, a
vendor may wish to describe additional information to definitions
in a "standard" module. This allows a vendor to implement
"standard" modules as well as additional private features, without
redundant module definitions, but on top of "standard" module
definitions.
12. Security Considerations
This document defines a language with which to write and read
descriptions of management information. The language itself has no
security impact on the Internet.
13. Acknowledgements
Since SMIng started as a close successor of SMIv2, some paragraphs
and phrases are directly taken from the SMIv2 specifications
[RFC2578], [RFC2579], [RFC2580] written by Jeff Case, Keith
McCloghrie, David Perkins, Marshall T. Rose, Juergen Schoenwaelder,
and Steven L. Waldbusser.
The authors would like to thank all participants of the 7th NMRG
meeting held in Schloss Kleinheubach from 6-8 September 2000, which
was a major step towards the current status of this memo, namely
Heiko Dassow, David Durham, Keith McCloghrie, and Bert Wijnen.
Furthermore, several discussions within the SMING Working Group
reflected experience with SMIv2 and influenced this specification at
some points.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
14.2. Informative References
[RFC3216] Elliott, C., Harrington, D., Jason, J., Schoenwaelder, J.,
Strauss, F. and W. Weiss, "SMIng Objectives", RFC 3216,
December 2001.
[RFC3781] Strauss, F. and J. Schoenwaelder, "Next Generation
Structure of Management Information (SMIng) Mappings to
the Simple Network Management Protocol (SNMP)", RFC 3781,
May 2004.
[RFC2578] McCloghrie, K., Perkins, D. and J. Schoenwaelder,
"Structure of Management Information Version 2 (SMIv2)",
STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Textual
Conventions for SMIv2", STD 59, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Perkins, D. and J. Schoenwaelder,
"Conformance Statements for SMIv2", STD 60, RFC 2580,
April 1999.
[RFC3159] McCloghrie, K., Fine, M., Seligson, J., Chan, K., Hahn,
S., Sahita, R., Smith, A. and F. Reichmeyer, "Structure of
Policy Provisioning Information (SPPI)", RFC 3159, August
2001.
[RFC1155] Rose, M. and K. McCloghrie, "Structure and Identification
of Management Information for TCP/IP-based Internets", STD
16, RFC 1155, May 1990.
[RFC1212] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD
16, RFC 1212, March 1991.
[RFC1215] Rose, M., "A Convention for Defining Traps for use with
the SNMP", RFC 1215, March 1991.
[ASN1] International Organization for Standardization,
"Specification of Abstract Syntax Notation One (ASN.1)",
International Standard 8824, December 1987.
[RFC3411] Harrington, D., Presuhn, R. and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
December 2002.
[IEEE754] Institute of Electrical and Electronics Engineers, "IEEE
Standard for Binary Floating-Point Arithmetic", ANSI/IEEE
Standard 754-1985, August 1985.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC3084] Chan, K., Seligson, J., Durham, D., Gai, S., McCloghrie,
K., Herzog, S., Reichmeyer, F., Yavatkar, R. and A. Smith,
"COPS Usage for Policy Provisioning", RFC 3084, March
2001.
Appendix A. NMRG-SMING Module
Most SMIng modules are built on top of the definitions of some
commonly used derived types. The definitions of these derived types
are contained in the NMRG-SMING module which is defined below. Its
derived types are generally applicable for modeling all areas of
management information. Among these derived types are counter types,
string types, and date and time related types.
This module is derived from RFC 2578 [RFC2578] and RFC 2579
[RFC2579].
module NMRG-SMING {
organization "IRTF Network Management Research Group (NMRG)";
contact "IRTF Network Management Research Group (NMRG)
http://www.ibr.cs.tu-bs.de/projects/nmrg/
Frank Strauss
TU Braunschweig
Muehlenpfordtstrasse 23
38106 Braunschweig
Germany
Phone: +49 531 391 3266
EMail: strauss@ibr.cs.tu-bs.de
Juergen Schoenwaelder
International University Bremen
P.O. Box 750 561
28725 Bremen
Germany
Phone: +49 421 200 3587
EMail: j.schoenwaelder@iu-bremen.de";
description "Core type definitions for SMIng. Several
type definitions are SMIng versions of
similar SMIv2 or SPPI definitions.
Copyright (C) The Internet Society (2004).
All Rights Reserved.
This version of this module is part of
RFC 3780, see the RFC itself for full
legal notices.";
revision {
date "2003-12-16";
description "Initial revision, published as RFC 3780.";
};
typedef Gauge32 {
type Unsigned32;
description
"The Gauge32 type represents a non-negative integer,
which may increase or decrease, but shall never
exceed a maximum value, nor fall below a minimum
value. The maximum value can not be greater than
2^32-1 (4294967295 decimal), and the minimum value
can not be smaller than 0. The value of a Gauge32
has its maximum value whenever the information
being modeled is greater than or equal to its
maximum value, and has its minimum value whenever
the information being modeled is smaller than or
equal to its minimum value. If the information
being modeled subsequently decreases below
(increases above) the maximum (minimum) value, the
Gauge32 also decreases (increases).";
reference
"RFC 2578, Sections 2. and 7.1.7.";
};
typedef Counter32 {
type Unsigned32;
description
"The Counter32 type represents a non-negative integer
which monotonically increases until it reaches a
maximum value of 2^32-1 (4294967295 decimal), when it
wraps around and starts increasing again from zero.
Counters have no defined `initial' value, and thus, a
single value of a Counter has (in general) no information
content. Discontinuities in the monotonically increasing
value normally occur at re-initialization of the
management system, and at other times as specified in the
description of an attribute using this type. If such
other times can occur, for example, the creation of a
class instance that contains an attribute of type
Counter32 at times other than re-initialization, then a
corresponding attribute should be defined, with an
appropriate type, to indicate the last discontinuity.
Examples of appropriate types include: TimeStamp32,
TimeStamp64, DateAndTime, TimeTicks32 or TimeTicks64
(other types defined in this module).
The value of the access statement for attributes with
a type value of Counter32 should be either `readonly'
or `eventonly'.
A default statement should not be used for attributes
with a type value of Counter32.";
reference
"RFC 2578, Sections 2. and 7.1.6.";
};
typedef Gauge64 {
type Unsigned64;
description
"The Gauge64 type represents a non-negative integer,
which may increase or decrease, but shall never
exceed a maximum value, nor fall below a minimum
value. The maximum value can not be greater than
2^64-1 (18446744073709551615), and the minimum value
can not be smaller than 0. The value of a Gauge64
has its maximum value whenever the information
being modeled is greater than or equal to its
maximum value, and has its minimum value whenever
the information being modeled is smaller than or
equal to its minimum value. If the information
being modeled subsequently decreases below
(increases above) the maximum (minimum) value, the
Gauge64 also decreases (increases).";
};
typedef Counter64 {
type Unsigned64;
description
"The Counter64 type represents a non-negative integer
which monotonically increases until it reaches a
maximum value of 2^64-1 (18446744073709551615), when
it wraps around and starts increasing again from zero.
Counters have no defined `initial' value, and thus, a
single value of a Counter has (in general) no
information content. Discontinuities in the
monotonically increasing value normally occur at
re-initialization of the management system, and at
other times as specified in the description of an
attribute using this type. If such other times can
occur, for example, the creation of a class
instance that contains an attribute of type Counter32
at times other than re-initialization, then
a corresponding attribute should be defined, with an
appropriate type, to indicate the last discontinuity.
Examples of appropriate types include: TimeStamp32,
TimeStamp64, DateAndTime, TimeTicks32 or TimeTicks64
(other types defined in this module).
The value of the access statement for attributes with
a type value of Counter64 should be either `readonly'
or `eventonly'.
A default statement should not be used for attributes
with a type value of Counter64.";
reference
"RFC 2578, Sections 2. and 7.1.10.";
};
typedef Opaque {
type OctetString;
status obsolete;
description
"******* THIS TYPE DEFINITION IS OBSOLETE *******
The Opaque type is provided solely for
backward-compatibility, and shall not be used for
newly-defined attributes and derived types.
The Opaque type supports the capability to pass
arbitrary ASN.1 syntax. A value is encoded using
the ASN.1 Basic Encoding Rules into a string of
octets. This, in turn, is encoded as an
OctetString, in effect `double-wrapping' the
original ASN.1 value.
Note that a conforming implementation need only be
able to accept and recognize opaquely-encoded data.
It need not be able to unwrap the data and then
interpret its contents.
A requirement on `standard' modules is that no
attribute may have a type value of Opaque and no
type may be derived from the Opaque type.";
reference
"RFC 2578, Sections 2. and 7.1.9.";
};
typedef IpAddress {
type OctetString (4);
status deprecated;
description
"******* THIS TYPE DEFINITION IS DEPRECATED *******
The IpAddress type represents a 32-bit Internet
IPv4 address. It is represented as an OctetString
of length 4, in network byte-order.
Note that the IpAddress type is present for
historical reasons.";
reference
"RFC 2578, Sections 2. and 7.1.5.";
};
typedef TimeTicks32 {
type Unsigned32;
description
"The TimeTicks32 type represents a non-negative integer
which represents the time, modulo 2^32 (4294967296
decimal), in hundredths of a second between two epochs.
When attributes are defined which use this type, the
description of the attribute identifies both of the
reference epochs.
For example, the TimeStamp32 type (defined in this
module) is based on the TimeTicks32 type.";
reference
"RFC 2578, Sections 2. and 7.1.8.";
};
typedef TimeTicks64 {
type Unsigned64;
description
"The TimeTicks64 type represents a non-negative integer
which represents the time, modulo 2^64
(18446744073709551616 decimal), in hundredths of a second
between two epochs. When attributes are defined which use
this type, the description of the attribute identifies
both of the reference epochs.
For example, the TimeStamp64 type (defined in this
module) is based on the TimeTicks64 type.";
};
typedef TimeStamp32 {
type TimeTicks32;
description
"The value of an associated TimeTicks32 attribute at
which a specific occurrence happened. The specific
occurrence must be defined in the description of any
attribute defined using this type. When the specific
occurrence occurred prior to the last time the
associated TimeTicks32 attribute was zero, then the
TimeStamp32 value is zero. Note that this requires all
TimeStamp32 values to be reset to zero when the value of
the associated TimeTicks32 attribute reaches 497+ days
and wraps around to zero.
The associated TimeTicks32 attribute should be specified
in the description of any attribute using this type.
If no TimeTicks32 attribute has been specified, the
default scalar attribute sysUpTime is used.";
reference
"RFC 2579, Section 2.";
};
typedef TimeStamp64 {
type TimeTicks64;
description
"The value of an associated TimeTicks64 attribute at which
a specific occurrence happened. The specific occurrence
must be defined in the description of any attribute
defined using this type. When the specific occurrence
occurred prior to the last time the associated TimeTicks64
attribute was zero, then the TimeStamp64 value is zero.
The associated TimeTicks64 attribute must be specified in
the description of any attribute using this
type. TimeTicks32 attributes must not be used as
associated attributes.";
};
typedef TimeInterval32 {
type Integer32 (0..2147483647);
description
"A period of time, measured in units of 0.01 seconds.
The TimeInterval32 type uses Integer32 rather than
Unsigned32 for compatibility with RFC 2579.";
reference
"RFC 2579, Section 2.";
};
typedef TimeInterval64 {
type Integer64;
description
"A period of time, measured in units of 0.01 seconds.
Note that negative values are allowed.";
};
typedef DateAndTime {
type OctetString (8 | 11);
default 0x0000000000000000000000;
format "2d-1d-1d,1d:1d:1d.1d,1a1d:1d";
description
"A date-time specification.
field octets contents range
----- ------ -------- -----
1 1-2 year* 0..65535
2 3 month 1..12 | 0
3 4 day 1..31 | 0
4 5 hour 0..23
5 6 minutes 0..59
6 7 seconds 0..60
(use 60 for leap-second)
7 8 deci-seconds 0..9
8 9 direction from UTC '+' / '-'
9 10 hours from UTC* 0..13
10 11 minutes from UTC 0..59
* Notes:
- the value of year is in big-endian encoding
- daylight saving time in New Zealand is +13
For example, Tuesday May 26, 1992 at 1:30:15 PM EDT would
be displayed as:
1992-5-26,13:30:15.0,-4:0
Note that if only local time is known, then timezone
information (fields 8-10) is not present.
The two special values of 8 or 11 zero bytes denote an
unknown date-time specification.";
reference
"RFC 2579, Section 2.";
};
typedef TruthValue {
type Enumeration (true(1), false(2));
description
"Represents a boolean value.";
reference
"RFC 2579, Section 2.";
};
typedef PhysAddress {
type OctetString;
format "1x:";
description
"Represents media- or physical-level addresses.";
reference
"RFC 2579, Section 2.";
};
typedef MacAddress {
type OctetString (6);
format "1x:";
description
"Represents an IEEE 802 MAC address represented in the
`canonical' order defined by IEEE 802.1a, i.e., as if it
were transmitted least significant bit first, even though
802.5 (in contrast to other 802.x protocols) requires MAC
addresses to be transmitted most significant bit first.";
reference
"RFC 2579, Section 2.";
};
// The DisplayString definition below does not impose a size
// restriction and is thus not the same as the DisplayString
// definition in RFC 2579. The DisplayString255 definition is
// provided for mapping purposes.
typedef DisplayString {
type OctetString;
format "1a";
description
"Represents textual information taken from the NVT ASCII
character set, as defined in pages 4, 10-11 of RFC 854.
To summarize RFC 854, the NVT ASCII repertoire specifies:
- the use of character codes 0-127 (decimal)
- the graphics characters (32-126) are interpreted as
US ASCII
- NUL, LF, CR, BEL, BS, HT, VT and FF have the special
meanings specified in RFC 854
- the other 25 codes have no standard interpretation
- the sequence 'CR LF' means newline
- the sequence 'CR NUL' means carriage-return
- an 'LF' not preceded by a 'CR' means moving to the
same column on the next line.
- the sequence 'CR x' for any x other than LF or NUL is
illegal. (Note that this also means that a string may
end with either 'CR LF' or 'CR NUL', but not with CR.)
";
};
typedef DisplayString255 {
type DisplayString (0..255);
description
"A DisplayString with a maximum length of 255 characters.
Any attribute defined using this syntax may not exceed 255
characters in length.
The DisplayString255 type has the same semantics as the
DisplayString textual convention defined in RFC 2579.";
reference
"RFC 2579, Section 2.";
};
// The Utf8String and Utf8String255 definitions below facilitate
// internationalization. The definition is consistent with the
// definition of SnmpAdminString in RFC 2571.
typedef Utf8String {
type OctetString;
format "65535t"; // is there a better way ?
description
"A human readable string represented using the ISO/IEC IS
10646-1 character set, encoded as an octet string using
the UTF-8 transformation format described in RFC 3629.
Since additional code points are added by amendments to
the 10646 standard from time to time, implementations must
be prepared to encounter any code point from 0x00000000 to
0x7fffffff. Byte sequences that do not correspond to the
valid UTF-8 encoding of a code point or are outside this
range are prohibited.
The use of control codes should be avoided. When it is
necessary to represent a newline, the control code
sequence CR LF should be used.
The use of leading or trailing white space should be
avoided.
For code points not directly supported by user interface
hardware or software, an alternative means of entry and
display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8
encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single
character / code point; thus the length of a Utf8String in
octets may be different from the number of characters
encoded. Similarly, size constraints refer to the number
of encoded octets, not the number of characters
represented by an encoding.";
};
typedef Utf8String255 {
type Utf8String (0..255);
format "255t";
description
"A Utf8String with a maximum length of 255 octets. Note
that the size of an Utf8String is measured in octets, not
characters.";
};
identity null {
description
"An identity used to represent null pointer values.";
};
};
Appendix B. SMIng ABNF Grammar
The SMIng grammar conforms to the Augmented Backus-Naur Form (ABNF)
[RFC2234].
;;
;; sming.abnf -- SMIng grammar in ABNF notation (RFC 2234).
;;
;; @(#) $Id: sming.abnf,v 1.33 2003/10/23 19:31:55 strauss Exp $
;;
;; Copyright (C) The Internet Society (2004). All Rights Reserved.
;;
smingFile = optsep *(moduleStatement optsep)
;;
;; Statement rules.
;;
moduleStatement = moduleKeyword sep ucIdentifier optsep
"{" stmtsep
*(importStatement stmtsep)
organizationStatement stmtsep
contactStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
1*(revisionStatement stmtsep)
*(extensionStatement stmtsep)
*(typedefStatement stmtsep)
*(identityStatement stmtsep)
*(classStatement stmtsep)
"}" optsep ";"
extensionStatement = extensionKeyword sep lcIdentifier optsep
"{" stmtsep
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
*1(abnfStatement stmtsep)
"}" optsep ";"
typedefStatement = typedefKeyword sep ucIdentifier optsep
"{" stmtsep
typedefTypeStatement stmtsep
*1(defaultStatement stmtsep)
*1(formatStatement stmtsep)
*1(unitsStatement stmtsep)
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
"}" optsep ";"
identityStatement = identityStmtKeyword sep lcIdentifier optsep
"{" stmtsep
*1(parentStatement stmtsep)
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
"}" optsep ";"
classStatement = classKeyword sep ucIdentifier optsep
"{" stmtsep
*1(extendsStatement stmtsep)
*(attributeStatement stmtsep)
*1(uniqueStatement stmtsep)
*(eventStatement stmtsep)
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
"}" optsep ";"
attributeStatement = attributeKeyword sep
lcIdentifier optsep
"{" stmtsep
typeStatement stmtsep
*1(accessStatement stmtsep)
*1(defaultStatement stmtsep)
*1(formatStatement stmtsep)
*1(unitsStatement stmtsep)
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
"}" optsep ";"
uniqueStatement = uniqueKeyword optsep
"(" optsep qlcIdentifierList
optsep ")" optsep ";"
eventStatement = eventKeyword sep lcIdentifier
optsep "{" stmtsep
statusStatement stmtsep
descriptionStatement stmtsep
*1(referenceStatement stmtsep)
"}" optsep ";"
importStatement = importKeyword sep ucIdentifier optsep
"(" optsep
identifierList optsep
")" optsep ";"
revisionStatement = revisionKeyword optsep "{" stmtsep
dateStatement stmtsep
descriptionStatement stmtsep
"}" optsep ";"
typedefTypeStatement = typeKeyword sep refinedBaseType optsep ";"
typeStatement = typeKeyword sep
(refinedBaseType / refinedType) optsep ";"
parentStatement = parentKeyword sep qlcIdentifier optsep ";"
extendsStatement = extendsKeyword sep qucIdentifier optsep ";"
dateStatement = dateKeyword sep date optsep ";"
organizationStatement = organizationKeyword sep text optsep ";"
contactStatement = contactKeyword sep text optsep ";"
formatStatement = formatKeyword sep format optsep ";"
unitsStatement = unitsKeyword sep units optsep ";"
statusStatement = statusKeyword sep status optsep ";"
accessStatement = accessKeyword sep access optsep ";"
defaultStatement = defaultKeyword sep anyValue optsep ";"
descriptionStatement = descriptionKeyword sep text optsep ";"
referenceStatement = referenceKeyword sep text optsep ";"
abnfStatement = abnfKeyword sep text optsep ";"
;;
;;
;;
refinedBaseType = ObjectIdentifierKeyword /
OctetStringKeyword *1(optsep numberSpec) /
PointerKeyword *1(optsep pointerSpec) /
Integer32Keyword *1(optsep numberSpec) /
Unsigned32Keyword *1(optsep numberSpec) /
Integer64Keyword *1(optsep numberSpec) /
Unsigned64Keyword *1(optsep numberSpec) /
Float32Keyword *1(optsep floatSpec) /
Float64Keyword *1(optsep floatSpec) /
Float128Keyword *1(optsep floatSpec) /
EnumerationKeyword
optsep namedSignedNumberSpec /
BitsKeyword optsep namedNumberSpec
refinedType = qucIdentifier *1(optsep anySpec)
anySpec = pointerSpec / numberSpec / floatSpec
pointerSpec = "(" optsep qlcIdentifier optsep ")"
numberSpec = "(" optsep numberElement
*furtherNumberElement
optsep ")"
furtherNumberElement = optsep "|" optsep numberElement
numberElement = signedNumber *1numberUpperLimit
numberUpperLimit = optsep ".." optsep signedNumber
floatSpec = "(" optsep floatElement
*furtherFloatElement
optsep ")"
furtherFloatElement = optsep "|" optsep floatElement
floatElement = floatValue *1floatUpperLimit
floatUpperLimit = optsep ".." optsep floatValue
namedNumberSpec = "(" optsep namedNumberList optsep ")"
namedNumberList = namedNumberItem
*(optsep "," optsep namedNumberItem)
namedNumberItem = lcIdentifier optsep "(" optsep number
optsep ")"
namedSignedNumberSpec = "(" optsep namedSignedNumberList optsep ")"
namedSignedNumberList = namedSignedNumberItem
*(optsep "," optsep
namedSignedNumberItem)
namedSignedNumberItem = lcIdentifier optsep "(" optsep signedNumber
optsep ")"
identifierList = identifier
*(optsep "," optsep identifier)
qIdentifierList = qIdentifier
*(optsep "," optsep qIdentifier)
qlcIdentifierList = qlcIdentifier
*(optsep "," optsep qlcIdentifier)
bitsValue = "(" optsep bitsList optsep ")"
bitsList = *1(lcIdentifier
*(optsep "," optsep lcIdentifier))
;;
;; Other basic rules.
;;
identifier = ucIdentifier / lcIdentifier
qIdentifier = qucIdentifier / qlcIdentifier
ucIdentifier = ucAlpha *63(ALPHA / DIGIT / "-")
qucIdentifier = *1(ucIdentifier "::") ucIdentifier
lcIdentifier = lcAlpha *63(ALPHA / DIGIT / "-")
qlcIdentifier = *1(ucIdentifier "::") lcIdentifier
attrIdentifier = lcIdentifier *("." lcIdentifier)
qattrIdentifier = *1(ucIdentifier ".") attrIdentifier
cattrIdentifier = ucIdentifier "."
lcIdentifier *("." lcIdentifier)
qcattrIdentifier = qucIdentifier "."
lcIdentifier *("." lcIdentifier)
text = textSegment *(optsep textSegment)
textSegment = DQUOTE *textAtom DQUOTE
; See Section 4.2.
textAtom = textVChar / HTAB / SP / lineBreak
date = DQUOTE 4DIGIT "-" 2DIGIT "-" 2DIGIT
*1(" " 2DIGIT ":" 2DIGIT)
DQUOTE
; always in UTC
format = textSegment
units = textSegment
anyValue = bitsValue /
signedNumber /
hexadecimalNumber /
floatValue /
text /
objectIdentifier
; Note: `objectIdentifier' includes the
; syntax of enumeration labels and
; identities.
; They are not named literally to
; avoid reduce/reduce conflicts when
; building LR parsers based on this
; grammar.
status = currentKeyword /
deprecatedKeyword /
obsoleteKeyword
access = eventonlyKeyword /
readonlyKeyword /
readwriteKeyword
objectIdentifier = (qlcIdentifier / subid "." subid)
*127("." subid)
subid = decimalNumber
number = hexadecimalNumber / decimalNumber
negativeNumber = "-" decimalNumber
signedNumber = number / negativeNumber
decimalNumber = "0" / (nonZeroDigit *DIGIT)
zeroDecimalNumber = 1*DIGIT
hexadecimalNumber = %x30 %x78 ; "0x" with x only lower-case
1*(HEXDIG HEXDIG)
floatValue = neginfKeyword /
posinfKeyword /
snanKeyword /
qnanKeyword /
signedNumber "." zeroDecimalNumber
*1("E" ("+"/"-") zeroDecimalNumber)
;;
;; Rules to skip unknown statements
;; with arbitrary arguments and blocks.
;;
unknownStatement = unknownKeyword optsep *unknownArgument
optsep ";"
unknownArgument = ("(" optsep unknownList optsep ")") /
("{" optsep *unknownStatement optsep "}") /
qucIdentifier /
anyValue /
anySpec
unknownList = namedNumberList /
qIdentifierList
unknownKeyword = lcIdentifier
;;
;; Keyword rules.
;;
;; Typically, keywords are represented by tokens returned from the
;; lexical analyzer. Note, that the lexer has to be stateful to
;; distinguish keywords from identifiers depending on the context
;; position in the input stream.
;;
moduleKeyword = %x6D %x6F %x64 %x75 %x6C %x65
importKeyword = %x69 %x6D %x70 %x6F %x72 %x74
revisionKeyword = %x72 %x65 %x76 %x69 %x73 %x69 %x6F %x6E
dateKeyword = %x64 %x61 %x74 %x65
organizationKeyword = %x6F %x72 %x67 %x61 %x6E %x69 %x7A %x61 %x74
%x69 %x6F %x6E
contactKeyword = %x63 %x6F %x6E %x74 %x61 %x63 %x74
descriptionKeyword = %x64 %x65 %x73 %x63 %x72 %x69 %x70 %x74 %x69
%x6F %x6E
referenceKeyword = %x72 %x65 %x66 %x65 %x72 %x65 %x6E %x63 %x65
extensionKeyword = %x65 %x78 %x74 %x65 %x6E %x73 %x69 %x6F %x6E
typedefKeyword = %x74 %x79 %x70 %x65 %x64 %x65 %x66
typeKeyword = %x74 %x79 %x70 %x65
parentKeyword = %x70 %x61 %x72 %x65 %x6E %x74
identityStmtKeyword = %x69 %x64 %x65 %x6E %x74 %x69 %x74 %x79
classKeyword = %x63 %x6C %x61 %x73 %x73
extendsKeyword = %x65 %x78 %x74 %x65 %x6E %x64 %x73
attributeKeyword = %x61 %x74 %x74 %x72 %x69 %x62 %x75 %x74 %x65
uniqueKeyword = %x75 %x6E %x69 %x71 %x75 %x65
eventKeyword = %x65 %x76 %x65 %x6E %x74
formatKeyword = %x66 %x6F %x72 %x6D %x61 %x74
unitsKeyword = %x75 %x6E %x69 %x74 %x73
statusKeyword = %x73 %x74 %x61 %x74 %x75 %x73
accessKeyword = %x61 %x63 %x63 %x65 %x73 %x73
defaultKeyword = %x64 %x65 %x66 %x61 %x75 %x6C %x74
abnfKeyword = %x61 %x62 %x6E %x66
;; Base type keywords.
OctetStringKeyword = %x4F %x63 %x74 %x65 %x74 %x53 %x74 %x72 %x69
%x6E %x67
PointerKeyword = %x50 %x6F %x69 %x6E %x74 %x65 %x72
ObjectIdentifierKeyword = %x4F %x62 %x6A %x65 %x63 %x74 %x49 %x64
%x65 %x6E %x74 %x69 %x66 %x69 %x65 %x72
Integer32Keyword = %x49 %x6E %x74 %x65 %x67 %x65 %x72 %x33 %x32
Unsigned32Keyword = %x55 %x6E %x73 %x69 %x67 %x6E %x65 %x64 %x33
%x32
Integer64Keyword = %x49 %x6E %x74 %x65 %x67 %x65 %x72 %x36 %x34
Unsigned64Keyword = %x55 %x6E %x73 %x69 %x67 %x6E %x65 %x64 %x36
%x34
Float32Keyword = %x46 %x6C %x6F %x61 %x74 %x33 %x32
Float64Keyword = %x46 %x6C %x6F %x61 %x74 %x36 %x34
Float128Keyword = %x46 %x6C %x6F %x61 %x74 %x31 %x32 %x38
BitsKeyword = %x42 %x69 %x74 %x73
EnumerationKeyword = %x45 %x6E %x75 %x6D %x65 %x72 %x61 %x74 %x69
%x6F %x6E
;; Status keywords.
currentKeyword = %x63 %x75 %x72 %x72 %x65 %x6E %x74
deprecatedKeyword = %x64 %x65 %x70 %x72 %x65 %x63 %x61 %x74 %x65
%x64
obsoleteKeyword = %x6F %x62 %x73 %x6F %x6C %x65 %x74 %x65
;; Access keywords.
eventonlyKeyword = %x65 %x76 %x65 %x6E %x74 %x6F %x6E %x6C %x79
readonlyKeyword = %x72 %x65 %x61 %x64 %x6F %x6E %x6C %x79
readwriteKeyword = %x72 %x65 %x61 %x64 %x77 %x72 %x69 %x74 %x65
;; Special floating point values' keywords.
neginfKeyword = %x6E %x65 %x67 %x69 %x6E %x66
posinfKeyword = %x70 %x6F %x73 %x69 %x6E %x66
snanKeyword = %x73 %x6E %x61 %x6E
qnanKeyword = %x71 %x6E %x61 %x6E
;;
;; Some low level rules.
;; These tokens are typically skipped by the lexical analyzer.
;;
sep = 1*(comment / lineBreak / WSP)
; unconditional separator
optsep = *(comment / lineBreak / WSP)
stmtsep = *(comment /
lineBreak /
WSP /
unknownStatement)
comment = "//" *(WSP / VCHAR) lineBreak
lineBreak = CRLF / LF
;;
;; Encoding specific rules.
;;
textVChar = %x21 / %x23-7E
; any VCHAR except DQUOTE
ucAlpha = %x41-5A
lcAlpha = %x61-7A
nonZeroDigit = %x31-39
;;
;; RFC 2234 core rules.
;;
ALPHA = %x41-5A / %x61-7A
; A-Z / a-z
CR = %x0D
; carriage return
CRLF = CR LF
; Internet standard newline
DIGIT = %x30-39
; 0-9
DQUOTE = %x22
; " (Double Quote)
HEXDIG = DIGIT /
%x61 / %x62 / %x63 / %x64 / %x65 / %x66
; only lower-case a..f
HTAB = %x09
; horizontal tab
LF = %x0A
; linefeed
SP = %x20
; space
VCHAR = %x21-7E
; visible (printing) characters
WSP = SP / HTAB
; white space
;; End of ABNF
Authors' Addresses
Frank Strauss
TU Braunschweig
Muehlenpfordtstrasse 23
38106 Braunschweig
Germany
Phone: +49 531 391 3266
EMail: strauss@ibr.cs.tu-bs.de
URI: http://www.ibr.cs.tu-bs.de/
Juergen Schoenwaelder
International University Bremen
P.O. Box 750 561
28725 Bremen
Germany
Phone: +49 421 200 3587
EMail: j.schoenwaelder@iu-bremen.de
URI: http://www.eecs.iu-bremen.de/
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