Network Working Group J. Schoenwaelder
Internet-Draft Jacobs University
Intended status: Standards Track March 14, 2011
Expires: September 15, 2011
Translation of SMIv2 MIB Modules to YANG Modules
draft-schoenw-netmod-smi-yang-02
Abstract
YANG is a data modeling language used to model configuration and
state data manipulated by the NETCONF protocol, NETCONF remote
procedure calls, and NETCONF notifications. The Structure of
Management Information (SMIv2) defines fundamental data types, an
object model, and the rules for writing and revising MIB modules for
use with the SNMP protocol. This document defines a translation of
SMIv2 MIB modules into YANG modules, enabling read-only access to
data objects defined in SMIv2 MIB modules via NETCONF.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on September 15, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Mapping of Special Types . . . . . . . . . . . . . . . . . . . 5
3. Module Prefix Generation . . . . . . . . . . . . . . . . . . . 6
4. Translation of SMIv2 Modules and SMIv2 IMPORT Clauses . . . . 7
4.1. Example: IMPORTS of IF-MIB . . . . . . . . . . . . . . . . 8
5. Translation of the MODULE-IDENTITY Macro . . . . . . . . . . . 9
5.1. MODULE-IDENTITY Translation Rules . . . . . . . . . . . . 9
5.2. Example: MODULE-IDENTITY of IF-MIB . . . . . . . . . . . . 9
6. Translation of the TEXTUAL-CONVENTION Macro . . . . . . . . . 11
6.1. TEXTUAL-CONVENTION Translation Rules . . . . . . . . . . . 11
6.2. Example: OwnerString and InterfaceIndex of IF-MIB . . . . 11
6.3. Example: IfDirection of the DIFFSERV-MIB . . . . . . . . . 12
7. Translation of OBJECT IDENTIFIER Assignments . . . . . . . . . 13
7.1. Object Identifier Assignment Translation Rules . . . . . . 13
7.2. Example: OBJECT IDENTIFIER Assignments of the IF-MIB . . . 13
8. Translation of the OBJECT-TYPE Macro . . . . . . . . . . . . . 14
8.1. Scalar and Columnar Object Translation Rules . . . . . . . 14
8.2. Example: ifNumber and ifIndex of the IF-MIB . . . . . . . 14
8.3. Non-Augmenting Conceptual Table Translation Rules . . . . 15
8.4. Example: ifTable of the IF-MIB . . . . . . . . . . . . . . 16
8.5. Example: ifRcvAddressTable of the IF-MIB . . . . . . . . . 16
8.6. Augmenting Conceptual Tables Translation Rules . . . . . . 18
8.7. Example: ifXTable of the IF-MIB . . . . . . . . . . . . . 18
9. Translation of the OBJECT-IDENTITY Macro . . . . . . . . . . . 20
9.1. OBJECT-IDENTITY Translation Rules . . . . . . . . . . . . 20
9.2. Example: diffServTBParamSimpleTokenBucket of the
DIFFSERV-MIB . . . . . . . . . . . . . . . . . . . . . . . 20
10. Translation of the NOTIFICATION-TYPE Macro . . . . . . . . . . 21
10.1. NOTIFICATION-TYPE Translation Rules . . . . . . . . . . . 21
10.2. Example: linkDown NOTIFICATION-TYPE of IF-MIB . . . . . . 21
11. YANG Language Extension Definition . . . . . . . . . . . . . . 24
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
13. Security Considerations . . . . . . . . . . . . . . . . . . . 27
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28
14.1. Normative References . . . . . . . . . . . . . . . . . . . 28
14.2. Informative References . . . . . . . . . . . . . . . . . . 28
Appendix A. Changes from 01 to 02 . . . . . . . . . . . . . . . . 29
Appendix B. Changes from 00 to 01 . . . . . . . . . . . . . . . . 30
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 31
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1. Introduction
This document describes an translation of SMIv2 [RFC2578], [RFC2579],
[RFC2580] MIB modules into YANG [RFC6020] modules, enabling read-only
access to data objects defined in SMIv2 MIB modules via NETCONF. The
mapping is illustrated by examples showing the translation of part of
the IF-MIB [RFC2863] SMIv2 module and the DIFFSERV-MIB [RFC3289]
SMIv2 module.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14, [RFC2119].
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2. Mapping of Special Types
The SMIv2 base types and some well known derived textual-conventions
are mapped to YANG types according to Table 1. The mapping of the
OCTET STRING depends on the context. If an OCTET STRING type has an
associated DISPLAY-HINT, then the corresponding YANG base type is the
string type. Otherwise, the binary type is used. Similarly, the
mapping of the INTEGER type depends on its usage as an enumeration or
a 32-bit integral type.
Mapping of SMIv2 types to YANG types
+------------+----------------+-----------------+-------------------+
| SMIv2 | SMIv2 Type | YANG Module | YANG Type |
| Module | | | |
+------------+----------------+-----------------+-------------------+
| SNMPv2-SMI | INTEGER | | enumeration |
| SNMPv2-SMI | INTEGER | | int32 |
| SNMPv2-SMI | Integer32 | | int32 |
| SNMPv2-SMI | OCTET STRING | | binary |
| SNMPv2-SMI | OCTET STRING | | string |
| SNMPv2-SMI | OBJECT | ietf-yang-types | object-identifier |
| | IDENTIFIER | | |
| SNMPv2-SMI | BITS | | bits |
| SNMPv2-SMI | IpAddress | ietf-inet-types | ipv4-address |
| SNMPv2-SMI | Counter32 | ietf-yang-types | counter32 |
| SNMPv2-SMI | Gauge32 | ietf-yang-types | gauge32 |
| SNMPv2-SMI | TimeTicks | ietf-yang-types | timeticks |
| SNMPv2-SMI | Opaque | | binary |
| SNMPv2-SMI | Counter64 | ietf-yang-types | counter64 |
| SNMPv2-SMI | Unsigned32 | | uint32 |
| SNMPv2-TC | PhysAddress | ietf-yang-types | phys-address |
| SNMPv2-TC | MacAddress | ietf-yang-types | mac-address |
| SNMPv2-TC | TimeStamp | ietf-yang-types | timestamp |
+------------+----------------+-----------------+-------------------+
Table 1
The mappings shown in Table 1 may impact the imports of the generated
YANG module since some SMIv2 types and textual-conventions map to
YANG types defined in the ietf-yang-types and ietf-inet-types YANG
modules [RFC6021]. Implementations must add any additional imports
required by the type mapping.
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3. Module Prefix Generation
The input of the prefix generation algorithm is a set of prefixes
(usually derived from imported module names) and a specific module
name to be converted into a prefix. The algorithm described below
produces a prefix for the given module name that is unique within the
set of prefixes.
Special prefixes for well known SMIv2 and YANG modules
+---------------------+--------+
| YANG / SMIv2 Module | Prefix |
+---------------------+--------+
| ietf-yang-types | yang |
| ietf-inet-types | inet |
| ietf-yang-smiv2 | smiv2 |
+---------------------+--------+
Table 2
o First, some fixed translations mapping well known SMIv2 and YANG
modules to short prefixes are tried (see Table 2). If a fixed
translation rule exists and leads to a conflict free prefix, then
the fixed translation is used.
o Otherwise, prefixes are generated by tokenizing an SMIv2 module
name where hyphens are considered as token separators. The tokens
derived with a module name are converted to lowercase characters.
The prefix then becomes the shortest sequence of token
concatenated using hyphens as separators, which includes at least
two token and which is unique among all prefixes used in the YANG
module.
In the worst case, the prefix derived from an SMIv2 module name
becomes the SMIv2 module name translated to lower-case. But on
average, much shorter prefixes are generated.
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4. Translation of SMIv2 Modules and SMIv2 IMPORT Clauses
SMIv2 modules are mapped to corresponding YANG modules. The YANG
module name is the same as the SMIv2 module name.
The YANG namespace is constructed out of a constant prefix followed
by the SMIv2 module name. Since SMIv2 module names are unique, the
resulting YANG namespace is unique. The registered prefix is
urn:ietf:params:xml:ns:yang:smiv2:, see the IANA considerations
section.
The YANG prefix is derived from the SMIv2 module name using the
module prefix generation algorithm described in Section 3. The YANG
prefix is supposed to be short and it must be unique within the set
of all prefixes used by a YANG module. The algorithm described in
Section 3 generates such prefixes.
SMIv2 IMPORT clauses are translated to YANG import statements. One
major difference between the SMIv2 import mechanism and the YANG
import mechanism is that SMIv2 IMPORT clauses import specific symbols
from an SMIv2 module while the YANG import statement imports all
symbols of the referenced YANG module.
SMIv2 imports that are ignored in YANG
+--------------+--------------------+
| SMIv2 Module | SMIv2 Symbol |
+--------------+--------------------+
| SNMPv2-SMI | MODULE-IDENTITY |
| SNMPv2-SMI | OBJECT-IDENTITY |
| SNMPv2-SMI | OBJECT-TYPE |
| SNMPv2-SMI | NOTIFICATION-TYPE |
| SNMPv2-SMI | mib-2 |
| SNMPv2-TC | TEXTUAL-CONVENTION |
| SNMPv2-CONF | OBJECT-GROUP |
| SNMPv2-CONF | NOTIFICATION-GROUP |
| SNMPv2-CONF | MODULE-COMPLIANCE |
| SNMPv2-CONF | AGENT-CAPABILITIES |
| SNMPv2-MIB | snmpTraps |
| SNMPv2-SMI | all symbols |
| SNMPv2-CONF | all symbols |
+--------------+--------------------+
Table 3
In order to produce correct and complete YANG import statements, it
is necessary to apply the following rules:
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o Ignore all imports listed in Table 3. Note that the modules
SNMPv2-SMI and SNMPv2-CONF are completely ignored since all
definitions in these modules are translated by translation rules.
o Add any imports required by the type translations according to the
type mapping table. This requires to consider all the types used
in the translation unit.
The argument of the generated import statements are the untranslated
SMIv2 module name. The import statement must contain a prefix
statement. The prefixes are generated by applying the module prefix
generation algorithm described in Section 3.
4.1. Example: IMPORTS of IF-MIB
The translation of the IF-MIB [RFC2863] leads to the YANG module
frame and the import statements shown below. The prefix is the
translation of the SMIv2 module name IF-MIB to lowercase (consisting
of two token and thus no further abbreviation).
module IF-MIB {
namespace "urn:ietf:params:xml:ns:yang:smiv2:IF-MIB";
prefix "if-mib";
import IANAifType-MIB { prefix "ianaiftype-mib"; }
import SNMPv2-TC { prefix "smiv2-tc"; }
import ietf-yang-types { prefix "yang"; }
import ietf-yang-smiv2 { prefix "smiv2"; }
}
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5. Translation of the MODULE-IDENTITY Macro
The clauses of the SMIv2 MODULE-IDENTITY macro are mapped to
equivalent YANG statements.
5.1. MODULE-IDENTITY Translation Rules
o The SMIv2 ORGANIZATION clause is mapped to the YANG organization
statement.
o The SMIv2 CONTACT-INFO clause is mapped to the YANG contact
statement.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o Each SMIv2 REVISION clause is mapped to a YANG revision statement.
The revision is identified by the date of contained in the SMIv2
REVISION. DESCRIPTION sub-clauses of REVISION clauses are mapped
to corresponding description statement nested in revision clauses.
o The SMIv2 LAST-UPDATED is ignored if the associated date matches a
REVISION clause. Otherwise, an additional revision statement is
generated.
o The value of the invocation of an SMIv2 MODULE-IDENTITY macro is
ignored.
While all proper SMIv2 modules must have a MODULE-IDENTITY macro
invocation, there are a few notable exceptions. The modules defining
the SMIv2 language (i.e., the SNMPv2-SMI, SNMPv2-TC, and SNMPv2-CONF
modules) do not invoke the MODULE-IDENTITY macro. Furthermore, SMIv2
modules generated out of SMIv1 modules may miss an invocation of the
MODULE-IDENTITY macro as well. In such cases, it is preferable to
not generate organization, contact, description, and revision
statements.
5.2. Example: MODULE-IDENTITY of IF-MIB
The translation of the MODULE-IDENTITY of the IF-MIB [RFC2863] leads
to the following YANG statements:
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organization
"IETF Interfaces MIB Working Group";
contact
"Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
US
408-526-5260
kzm@cisco.com";
description
"The MIB module to describe generic objects for network
interface sub-layers. This MIB is an updated version of
MIB-II's ifTable, and incorporates the extensions defined in
RFC 1229.";
revision "2000-06-14" {
description
"Clarifications agreed upon by the Interfaces MIB WG, and
published as RFC 2863.";
}
revision "1996-02-28" {
description
"Revisions made by the Interfaces MIB WG, and published in
RFC 2233.";
}
revision "1993-11-08" {
description
"Initial revision, published as part of RFC 1573.";
}
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6. Translation of the TEXTUAL-CONVENTION Macro
The SMIv2 uses invocations of the TEXTUAL-CONVENTION macro to define
new types derived from the SMIv2 base types. Invocations of the
TEXTUAL-CONVENTION macro are translated into YANG typedef statements.
6.1. TEXTUAL-CONVENTION Translation Rules
The name of the TEXTUAL-CONVENTION macro invocation is used as the
name of the generated typedef statement. The clauses of the SMIv2
TEXTUAL-CONVENTION macro are mapped to YANG statements embedded in
the typedef statement as follows:
o The SMIv2 DISPLAY-HINT clause is used to determine the type
mapping of types derived form the OCTET STRING type as explained
in Section 2. Furthermore, the DISPLAY-HINT value MAY be used to
generate a regular expression for the YANG pattern statement
within the type statement. [[TODO: Define a translation algorithm
that is simple and produces correct and usable results for the
majority of simple DISPLAY-HINTS?]]
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
o The SMIv2 SYNTAX clause is mapped to the YANG type statement.
SMIv2 range restrictions are mapped to YANG range statements while
SMIv2 length restrictions are mapped to YANG length statements.
SMIv2 INTEGER enumerations and SMIv2 BITS are mapped to YANG enum
/ value and bit / position statements.
6.2. Example: OwnerString and InterfaceIndex of IF-MIB
The translation of the OwnerString and InterfaceIndex textual-
conventions of the IF-MIB [RFC2863] are shown below.
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typedef OwnerString {
type string {
length "0..255";
pattern "\p{IsBasicLatin}{0,255}";
}
status deprecated;
description
"This data type is used to model an administratively
assigned name of the owner of a resource. This information
is taken from the NVT ASCII character set. It is suggested
that this name contain one or more of the following: ASCII
form of the manager station's transport address, management
station name (e.g., domain name), network management
personnel's name, location, or phone number. In some cases
the agent itself will be the owner of an entry. In these
cases, this string shall be set to a string starting with
'agent'.";
}
typedef InterfaceIndex {
type int32 {
range "1..2147483647";
}
description
"A unique value, greater than zero, for each interface or
interface sub-layer in the managed system. It is
recommended that values are assigned contiguously starting
from 1. The value for each interface sub-layer must remain
constant at least from one re-initialization of the entity's
network management system to the next re-initialization.";
}
6.3. Example: IfDirection of the DIFFSERV-MIB
The translation of the IfDirection textual-convention of the
DIFFSERV-MIB [RFC3289] is shown below.
typedef IfDirection {
type enumeration {
enum inbound { value 1; }
enum outbound { value 2; }
}
description
"IfDirection specifies a direction of data travel on an
interface. 'inbound' traffic is operated on during reception from
the interface, while 'outbound' traffic is operated on prior to
transmission on the interface.";
}
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7. Translation of OBJECT IDENTIFIER Assignments
The mapping suppresses many structural OBJECT IDENTIFIER assignments
that are typically used to organize the OBJECT IDENTIFIER tree.
7.1. Object Identifier Assignment Translation Rules
o Object identifier assignments through ASN.1 value assignments or
through the invocation of a MODULE-IDENTITY clause are translated
to YANG container statements.
o Top-level container must be marked as config false.
o Implementations MAY suppress the generation of YANG containers for
object identifiers that only contain SMIv2 conformance
definitions.
[[TODO: What do we do if multiple assignments exist for the same OID
value?]]
7.2. Example: OBJECT IDENTIFIER Assignments of the IF-MIB
The translation of the OBJECT IDENTIFIER assignments and the value of
the MODULE-IDENTITY clause of the IF-MIB [RFC2863] is shown below.
container interfaces {
config false;
// ...
}
container ifMIB {
config false;
container ifMIBObjects {
// ...
}
container ifConformance {
container ifGroups {
// ...
}
container ifCompliances {
// ...
}
}
}
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8. Translation of the OBJECT-TYPE Macro
The SMIv2 uses the OBJECT-TYPE macro to define objects and the
structure of conceptual tables. Objects exist either as scalars
(exactly one instance within an SNMP context) or columnar objects
(zero or multiple instances within an SNMP context) within conceptual
tables. A number of auxiliary objects define the index (key) of the
table. Furthermore, conceptual tables can be augmented by other
conceptual tables. All these differences must be taken into account
when mapping SMIv2 OBJECT-TYPE macro invocations to YANG.
8.1. Scalar and Columnar Object Translation Rules
The SMIv2 OBJECT-TYPE macro invocations defining scalars or columnar
objects are translated to YANG leaf statements. The name of the leaf
is the name associated with the SMIv2 OBJECT-TYPE macro invocation.
o The SMIv2 SYNTAX clause is mapped to the YANG type clause.
Embedded clauses are generates as described in Section 2.
o The SMIv2 UNITS clause is mapped to the YANG units statement.
o The SMIv2 MAX-ACCESS clause is ignored.
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
o The value of the SMIv2 OBJECT-TYPE macro invocation is ignored.
8.2. Example: ifNumber and ifIndex of the IF-MIB
The translations of the ifNumber scalar object and the ifIndex
columnar object of the IF-MIB [RFC2863] are shown below.
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leaf ifNumber {
type int32;
description
"The number of network interfaces (regardless of their
current state) present on this system.";
}
leaf ifIndex {
type if-mib:InterfaceIndex;
description
"A unique value, greater than zero, for each interface. It
is recommended that values are assigned contiguously
starting from 1. The value for each interface sub-layer
must remain constant at least from one re-initialization of
the entity's network management system to the next re-
initialization.";
}
8.3. Non-Augmenting Conceptual Table Translation Rules
An OBJECT-TYPE clause defining a non-augmenting conceptual table is
translated to a YANG container statement using the name of the table
OBJECT-TYPE clause. The OBJECT-TYPE clause representing a table row
is translated to a YANG list statement using the name of the row
OBJECT-TYPE clause. The rest of the clauses are translated as
follows:
o The SMIv2 SYNTAX clause is ignored.
o The SMIv2 UNITS clause is ignored.
o The SMIv2 MAX-ACCESS clause is ignored.
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
o The SMIv2 INDEX clause is mapped to the YANG key clause listing
the columnar objects forming the key of the YANG list.
o The value of the SMIv2 OBJECT-TYPE macro invocation is ignored.
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Within the list statement, YANG leaf statements are created for
columnar objects as described above. For objects listed in the SMIv2
INDEX clause that are not part of the conceptual table itself, YANG
leaf statements of type leafref pointing to the referenced definition
are created.
8.4. Example: ifTable of the IF-MIB
The translation of the definition of the ifTable of the IF-MIB
[RFC2863] is shown below.
container ifTable {
description
"A list of interface entries. The number of entries is
given by the value of ifNumber.";
list ifEntry {
key "ifIndex";
description
"An entry containing management information applicable to a
particular interface.";
// ...
}
}
8.5. Example: ifRcvAddressTable of the IF-MIB
The translation of the definition of the ifRcvAddressTable of the IF-
MIB [RFC2863] is shown below.
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container ifRcvAddressTable {
description
"This table contains an entry for each address (broadcast,
multicast, or uni-cast) for which the system will receive
packets/frames on a particular interface, except as follows:
- for an interface operating in promiscuous mode, entries
are only required for those addresses for which the system
would receive frames were it not operating in promiscuous
mode.
- for 802.5 functional addresses, only one entry is
required, for the address which has the functional address
bit ANDed with the bit mask of all functional addresses for
which the interface will accept frames.
A system is normally able to use any unicast address which
corresponds to an entry in this table as a source address.";
list ifRcvAddressEntry {
key "ifIndex ifRcvAddressAddress";
description
"A list of objects identifying an address for which the
system will accept packets/frames on the particular
interface identified by the index value ifIndex.";
leaf ifIndex {
type leafref {
path "/if-mib:interfaces/if-mib:ifTable" +
"/if-mib:ifEntry/if-mib:ifIndex";
}
description
"[Automatically generated leaf for a foreign index.]";
}
leaf ifRcvAddressAddress {
type yang:phys-address;
description
"An address for which the system will accept packets/frames
on this entry's interface.";
}
// ...
}
}
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8.6. Augmenting Conceptual Tables Translation Rules
An OBJECT-TYPE clause defining an augmenting conceptual table is
translated to a YANG container statement using the name of the table
OBJECT-TYPE clause. The OBJECT-TYPE clause representing a table row
is translated to a YANG augment statement using the path to the
augmented table. The rest of the clauses are translated as follows:
o The SMIv2 SYNTAX clause is ignored.
o The SMIv2 UNITS clause is ignored.
o The SMIv2 MAX-ACCESS clause is ignored.
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
o The value of the SMIv2 OBJECT-TYPE macro invocation is ignored.
Within the augment statement, YANG leaf nodes are created as
described above.
8.7. Example: ifXTable of the IF-MIB
The translation of the definition of the ifXTable of the IF-MIB
[RFC2863] is shown below.
container ifXTable {
description
"A list of interface entries. The number of entries is
given by the value of ifNumber. This table contains
additional objects for the interface table."
augment "/if-mib:interfaces/if-mib:ifTable" +
"/if-mib:ifEntry" {
description
"An entry containing additional management information
applicable to a particular interface.";
// ...
}
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}
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9. Translation of the OBJECT-IDENTITY Macro
Invocations of the OBJECT-IDENTITY macro are translated into YANG
container statements.
9.1. OBJECT-IDENTITY Translation Rules
The name of the OBJECT-IDENTITY macro invocation is used as the name
of the generated container statement. Any generated top-level
container must be marked as config false. The clauses of the SMIv2
OBJECT-IDENTITY macro are mapped to YANG statements as follows:
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
9.2. Example: diffServTBParamSimpleTokenBucket of the DIFFSERV-MIB
The translation of the diffServTBParamSimpleTokenBucket of the
DIFFSERV-MIB [RFC3289] is shown below.
container diffServTBParamSimpleTokenBucket {
description
"Two Parameter Token Bucket Meter as described in the Informal
Differentiated Services Model section 5.2.3.";
}
[[TODO: Should we in addition generate toplevel YANG identities so
that definitions can be referenced from new YANG modules? See the
example below (which assumes we provide an smiv2:object-identity
base).]]
identity diffServTBParamSimpleTokenBucket {
base "smiv2:object-identity";
description
"Two Parameter Token Bucket Meter as described in the Informal
Differentiated Services Model section 5.2.3.";
}
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10. Translation of the NOTIFICATION-TYPE Macro
The SMIv2 provides the NOTIFICATION-TYPE macro to define
notifications. YANG provides the notification statement for the same
purpose.
10.1. NOTIFICATION-TYPE Translation Rules
The name of the NOTIFICATION-TYPE macro invocation is used as the
name of the generated notification statement. The clauses of the
NOTIFICATION-TYPE macro are mapped to YANG statements embedded in the
notification statement as follows.
o The SMIv2 OBJECTS clause is mapped to a sequence of YANG
containers. For each object listed in the OBJECTS clause value, a
YANG container statement is generated. The name of this container
is the name of the notification and the name of the current
concatenated by a hyphen. If the current object belongs a
conceptual table, then a sequence of leaf statements is generated
for each INDEX of the SMIv2 conceptual table. Next, a leaf
statement is generated for the current object. All container
leafs are marked as config false.
o The SMIv2 STATUS clause is mapped to the YANG status statement.
The generation of the YANG status statement is skipped if the
value of the STATUS clause is current.
o The SMIv2 DESCRIPTION clause is mapped to the YANG description
statement.
o The SMIv2 REFERENCE clause is mapped to the YANG reference
statement.
o The value of the SMIv2 NOTIFICATION-TYPE macro invocation is
ignored.
10.2. Example: linkDown NOTIFICATION-TYPE of IF-MIB
The translation of the linkDown notification of the IF-MIB [RFC2863]
is shown below.
notification linkDown {
description
"A linkDown trap signifies that the SNMP entity, acting in
an agent role, has detected that the ifOperStatus object for
one of its communication links 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
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of ifOperStatus.";
container linkDown-ifIndex {
config false;
leaf ifIndex {
type leafref {
path "/if-mib:interfaces/if-mib:ifTable" +
"/if-mib:ifEntry/if-mib:ifIndex";
}
description
"[Automatically generated leaf for a notification.]";
}
}
container linkDown-ifAdminStatus {
config false;
leaf ifIndex {
type leafref {
path "/if-mib:interfaces/if-mib:ifTable" +
"/if-mib:ifEntry/if-mib:ifIndex";
}
description
"[Automatically generated leaf for a notification.]";
}
leaf ifAdminStatus {
type enumeration {
enum up { value 1; }
enum down { value 2; }
enum testing { value 3; }
}
description
"The desired state of the interface. The testing(3) state
indicates that no operational packets can be passed. When a
managed system initializes, all interfaces start with
ifAdminStatus in the down(2) state. As a result of either
explicit management action or per configuration information
retained by the managed system, ifAdminStatus is then
changed to either the up(1) or testing(3) states (or remains
in the down(2) state).";
}
}
container linkDown-ifOperStatus {
config false;
leaf ifIndex {
type leafref {
path "/if-mib:interfaces/if-mib:ifTable" +
"/if-mib:ifEntry/if-mib:ifIndex";
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}
description
"[Automatically generated leaf for a notification.]";
}
leaf ifOperStatus {
type enumeration {
enum up { value 1; }
enum down { value 2; }
enum testing { value 3; }
enum unknown { value 4; }
enum dormant { value 5; }
enum notPresent { value 6; }
enum lowerLayerDown { value 7; }
}
description
"The current operational state of the interface. The
testing(3) state indicates that no operational packets can
be passed. If ifAdminStatus is down(2) then ifOperStatus
should be down(2). If ifAdminStatus is changed to up(1)
then ifOperStatus should change to up(1) if the interface is
ready to transmit and receive network traffic; it should
change to dormant(5) if the interface is waiting for
external actions (such as a serial line waiting for an
incoming connection); it should remain in the down(2) state
if and only if there is a fault that prevents it from going
to the up(1) state; it should remain in the notPresent(6)
state if the interface has missing (typically, hardware)
components.";
}
}
}
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11. YANG Language Extension Definition
This section defines some YANG extension statements that can be used
to carry additional information from the original SMIv2 module into
the YANG module. The YANG module references [RFC2578] and [RFC2579].
<CODE BEGINS> file "ietf-yang-smiv2@2011-03-14.yang"
module ietf-yang-smiv2 {
namespace "urn:ietf:params:xml:ns:yang:ietf-yang-smiv2";
prefix "smiv2";
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
WG Chair: David Kessens
<mailto:david.kessens@nsn.com>
WG Chair: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>
Editor: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>";
description
"This module defines YANG extensions that are used to translate
SMIv2 concepts into YANG.
Copyright (c) 2011 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this note
// RFC Ed.: please update the date to the date of publication
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revision 2011-03-14 {
description
"Initial revision.";
reference
"RFC XXXX: Translation of SMIv2 MIB Modules to YANG Modules";
// RFC Ed.: replace XXXX with actual RFC number and remove this note
}
extension oid {
argument "value";
description
"The oid statement takes as an argument the object identifier
assigned to an SMIv2 definition. The object identifier value
is written in decimal dotted notation.";
reference
"RFC2578: Structure of Management Information Version 2 (SMIv2)";
}
extension display-hint {
argument "format";
description
"The display-hint statement takes as an argument the DISPLAY-HINT
assigned to an SMIv2 textual convention.";
reference
"RFC2579: Textual Conventions for SMIv2";
}
extension max-access {
argument "access";
description
"The max-access statement takes as an argument the MAX-ACCESS
assigned to an SMIv2 object definition";
reference
"RFC2578: Structure of Management Information Version 2 (SMIv2)";
}
extension defval {
argument "value";
description
"The defval statement takes as an argument a default value defined
by an SMIv2 DEFVAL clause.";
reference
"RFC2578: Structure of Management Information Version 2 (SMIv2)";
}
}
<CODE ENDS>
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12. IANA Considerations
This document registers two URIs in the IETF XML registry [RFC3688].
Following the format in RFC 3688, the following registrations have
been made.
URI: urn:ietf:params:xml:ns:yang:ietf-yang-smiv2
Registrant Contact: The NETMOD WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:smiv2
Registrant Contact: The NETMOD WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers a YANG module in the YANG Module Names
registry [RFC6020].
name: ietf-yang-smiv2
namespace: urn:ietf:params:xml:ns:yang:ietf-yang-smiv2
prefix: smiv2
reference: RFC XXXX
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13. Security Considerations
This document defines a translation of the SMIv2 data modeling
language to the YANG data modeling language. The translation itself
has no security impact on the Internet.
Users of translated SMIv2 data models that have been published as
RFCs should consult the security considerations of the respective
RFCs. In addition, the security considerations for the NETCONF
protocol [RFC4741] should be consulted to understand how NETCONF
protects potentially sensitive information.
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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.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2579] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Textual Conventions for SMIv2",
STD 58, RFC 2579, April 1999.
[RFC2580] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Conformance Statements for SMIv2", STD 58, RFC 2580,
April 1999.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC6021] Schoenwaelder, J., "Common YANG Data Types", RFC 6021,
October 2010.
14.2. Informative References
[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
MIB", RFC 2863, June 2000.
[RFC3289] Baker, F., Chan, K., and A. Smith, "Management Information
Base for the Differentiated Services Architecture",
RFC 3289, May 2002.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
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Appendix A. Changes from 01 to 02
o Preserving the SMIv2 nesting instead of a flat translation.
o Inlined the examples to avoid page flipping exercises.
o Clarifications and several editorial improvements.
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Appendix B. Changes from 00 to 01
o Translation is config false; top-level container are marked as
config false.
o Revised the overall document structure, added a YANG module for
the definition of YANG extensions (smiv2:oid, smiv2:display-hint,
smiv2:max-access, smiv2:defval), moved the IF-MIB example into an
appendix.
o Alignment with RFC 6020 and RFC 6021.
o Started to use [[TODO]] markers inside the text instead of
maintaining a TODO list as an appendix.
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Author's Address
Juergen Schoenwaelder
Jacobs University
Email: j.schoenwaelder@jacobs-university.de
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