Common YANG Data Types
RFC 9911
Jürgen Schönwälder, Ed.
Constructor University
jschoenwaelder@constructor.university
December 2025
OPS
netmod
This document defines a collection of common data types to be used with the YANG data modeling language. It includes several new type definitions and obsoletes RFC 6991.
Introduction
YANG [RFC7950] is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF) [RFC6241]. The YANG language supports a small set of built-in data types and provides mechanisms to derive other types from the built-in types.
This document defines a collection of common data types. The definitions are organized into two YANG modules:
- The "ietf-yang-types" module defines generally useful data types such as types for counters and gauges, types related to date and time, and types for common string values (e.g., UUIDs, dotted-quad notation, and language tags).
- The "ietf-inet-types" module defines data types relevant for the Internet Protocol suite such as types related to IP addresses, types for domain name, host name, URI, and email, and types for values in common protocol fields (e.g., port numbers).
The initial version of these YANG modules was published as [RFC6021]. The first revision of [RFC6021], published as [RFC6991], added several type definitions to the YANG modules. This second revision adds further new type definitions and addresses Erratum IDs 4076 [Err4076] and 5105 [Err5105]. Furthermore, the yang-identifier definition has been aligned with YANG 1.1 [RFC7950], and some pattern statements have been improved. For further details, see the revision statements of the YANG modules in Sections 3 and 4. A brief overview of all types and when they were introduced can be found in Section 2. Additional type definitions may be added in the future by submitting proposals to the NETMOD Working Group.
This document uses the YANG terminology defined in Section 3 of [RFC7950].
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] [RFC8174] when, and only when, they appear in all capitals, as shown here.
Overview
Tables 1 and 2 list the types defined in the YANG modules "ietf-yang-types" and "ietf-inet-types". For each type, the name of the type, the base type it was derived from, and the RFC introducing the type is listed.
Types Defined in the "ietf-yang-types" Module
Type | Base Type | Introduced in
counter32 | uint32 | RFC 6021
zero-based-counter32 | uint32 | RFC 6021
counter64 | uint64 | RFC 6021
zero-based-counter64 | uint64 | RFC 6021
gauge32 | uint32 | RFC 6021
gauge64 | uint64 | RFC 6021
object-identifier | string | RFC 6021
object-identifier-128 | object-identifier | RFC 6021
date-and-time | string | RFC 6021
date | string | RFC 9911
date-no-zone | string | RFC 9911
time | string | RFC 9911
time-no-zone | string | RFC 9911
hours32 | int32 | RFC 9911
minutes32 | int32 | RFC 9911
seconds32 | int32 | RFC 9911
centiseconds32 | int32 | RFC 9911
milliseconds32 | int32 | RFC 9911
microseconds32 | int32 | RFC 9911
microseconds64 | int64 | RFC 9911
nanoseconds32 | int32 | RFC 9911
nanoseconds64 | int64 | RFC 9911
timeticks | int32 | RFC 6021
timestamp | timeticks | RFC 6021
phys-address | string | RFC 6021
mac-address | string | RFC 6021
xpath1.0 | string | RFC 6021
hex-string | string | RFC 6991
uuid | string | RFC 6991
dotted-quad | string | RFC 6991
language-tag | string | RFC 9911
yang-identifier | string | RFC 6991
Types Defined in the "ietf-inet-types" Module
Type | Base Type | Introduced in
ip-version | enum | RFC 6021
dscp | uint8 | RFC 6021
ipv6-flow-label | uint32 | RFC 6021
port-number | uint16 | RFC 6021
protocol-number | uint8 | RFC 9911
upper-layer-protocol-number | protocol-number | RFC 9911
as-number | uint32 | RFC 6021
ip-address | union | RFC 6021
ipv4-address | string | RFC 6021
ipv6-address | string | RFC 6021
ip-address-no-zone | union | RFC 6991
ipv4-address-no-zone | ipv4-address | RFC 6991
ipv6-address-no-zone | ipv6-address | RFC 6991
ip-address-link-local | union | RFC 9911
ipv4-address-link-local | ipv4-address | RFC 9911
ipv6-address-link-local | ipv6-address | RFC 9911
ip-prefix | union | RFC 6021
ipv4-prefix | string | RFC 6021
ipv6-prefix | string | RFC 6021
ip-address-and-prefix | union | RFC 9911
ipv4-address-and-prefix | string | RFC 9911
ipv6-address-and-prefix | string | RFC 9911
domain-name | string | RFC 6021
host-name | domain-name | RFC 9911
host | union | RFC 6021
uri | string | RFC 6021
email-address | string | RFC 9911
Some types have an equivalent Structure of Management Information Version 2 (SMIv2) [RFC2578] [RFC2579] data type. A YANG data type is equivalent to an SMIv2 data type if the data types have the same set of values and the semantics of the values are equivalent.
Table 3 lists the types defined in the "ietf-yang-types" YANG module with their corresponding SMIv2 types, and Table 4 lists the types defined in the "ietf-inet-types" module with their corresponding SMIv2 types.
Equivalent SMIv2 Types for the "ietf-yang-types" Module
YANG type | Equivalent SMIv2 type (module)
counter32 | Counter32 (SNMPv2-SMI)
zero-based-counter32 | ZeroBasedCounter32 (RMON2-MIB)
counter64 | Counter64 (SNMPv2-SMI)
zero-based-counter64 | ZeroBasedCounter64 (HCNUM-TC)
gauge32 | Gauge32 (SNMPv2-SMI)
gauge64 | CounterBasedGauge64 (HCNUM-TC)
object-identifier-128 | OBJECT IDENTIFIER
centiseconds32 | TimeInterval (SNMPv2-TC)
timeticks | TimeTicks (SNMPv2-SMI)
timestamp | TimeStamp (SNMPv2-TC)
phys-address | PhysAddress (SNMPv2-TC)
mac-address | MacAddress (SNMPv2-TC)
language-tag | LangTag (LANGTAG-TC-MIB)
Equivalent SMIv2 Types for the "ietf-inet-types" Module
YANG type | Equivalent SMIv2 type (module)
ip-version | InetVersion (INET-ADDRESS-MIB)
dscp | Dscp (DIFFSERV-DSCP-TC)
ipv6-flow-label | IPv6FlowLabel (IPV6-FLOW-LABEL-MIB)
port-number | InetPortNumber (INET-ADDRESS-MIB)
as-number | InetAutonomousSystemNumber (INET-ADDRESS-MIB)
uri | Uri (URI-TC-MIB)
Core YANG Types
The "ietf-yang-types" YANG module references [IEEE-802-2024], [ISO-8601], [ISO-9834-1], [RFC2578], [RFC2579], [RFC2856], [RFC3339], [RFC4502], [RFC5131], [RFC5646], [RFC7950], [RFC9557], [RFC9562], [XPATH], and [XSD-TYPES].

module ietf-yang-types {
  namespace "urn:ietf:params:xml:ns:yang:ietf-yang-types";
  prefix yang;

  organization
    "IETF Network Modeling (NETMOD) Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
     WG List:  <mailto:netmod@ietf.org>

     Editor:   Jürgen Schönwälder
               <mailto:jschoenwaelder@constructor.university>";
  description
    "This module contains a collection of generally useful derived
     YANG data types.

     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 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.

     Copyright (c) 2025 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 Revised BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9911;
     see the RFC itself for full legal notices.";

  revision 2025-12-01 {
    description
      "This revision adds the following new data types:
       - yang:date
       - yang:date-no-zone
       - yang:time
       - yang:time-no-zone
       - yang:hours32
       - yang:minutes32
       - yang:seconds32
       - yang:centiseconds32
       - yang:milliseconds32
       - yang:microseconds32
       - yang:microseconds64
       - yang:nanoseconds32
       - yang:nanoseconds64
       - yang:language-tag
       The yang-identifier definition has been aligned with YANG
       1.1, and types representing time support the representation
       of leap seconds.  The representation of time zone offsets
       has been aligned with RFC 9557.  Several description and
       pattern statements have been improved.";
    reference
      "RFC 9911: Common YANG Data Types";
  }
  revision 2013-07-15 {
    description
      "This revision adds the following new data types:
       - yang:yang-identifier
       - yang:hex-string
       - yang:uuid
       - yang:dotted-quad";
    reference
      "RFC 6991: Common YANG Data Types";
  }
  revision 2010-09-24 {
    description
      "Initial revision.";
    reference
      "RFC 6021: Common YANG Data Types";
  }

  /*** collection of counter and gauge types ***/

  typedef counter32 {
    type uint32;
    description
      "The counter32 type represents a non-negative integer
       that 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 a schema node using this type.  If
       discontinuities occur at times other than re-initialization
       (for example, at the instantiation of a schema node of type
       counter32), then a corresponding schema node should be
       defined, with an appropriate type, to indicate the last
       discontinuity.

       The counter32 type should not be used for configuration
       schema nodes.  A default statement SHOULD NOT be used in
       combination with the type counter32.

       In the value set and its semantics, this type is equivalent
       to the Counter32 type of the SMIv2.";
    reference
      "RFC 2578: Structure of Management Information Version 2
                 (SMIv2)";
  }

  typedef zero-based-counter32 {
    type counter32;
    default "0";
    description
      "The zero-based-counter32 type represents a counter32
       that has the defined 'initial' value zero.

       A data tree node using this type will be set to zero (0)
       on creation and will thereafter increase monotonically until
       it reaches a maximum value of 2^32-1 (4294967295 decimal),
       when it wraps around and starts increasing again from zero.

       Provided that an application discovers a new data tree node
       using this type within the minimum time to wrap, it can use
       the 'initial' value as a delta.  It is important for a
       management station to be aware of this minimum time and the
       actual time between polls, and to discard data if the actual
       time is too long or there is no defined minimum time.

       In the value set and its semantics, this type is equivalent
       to the ZeroBasedCounter32 textual convention of the SMIv2.";
    reference
      "RFC 4502: Remote Network Monitoring Management Information
                 Base Version 2";
  }

  typedef counter64 {
    type uint64;
    description
      "The counter64 type represents a non-negative integer
       that monotonically increases until it reaches a
       maximum value of 2^64-1 (18446744073709551615 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 a schema node using this type.  If
       discontinuities occur at times other than re-initialization
       (for example, at the instantiation of a schema node of type
       counter64), then a corresponding schema node should be
       defined, with an appropriate type, to indicate the last
       discontinuity.

       The counter64 type should not be used for configuration
       schema nodes.  A default statement SHOULD NOT be used in
       combination with the type counter64.

       In the value set and its semantics, this type is equivalent
       to the Counter64 type of the SMIv2.";
    reference
      "RFC 2578: Structure of Management Information Version 2
                 (SMIv2)";
  }

  typedef zero-based-counter64 {
    type counter64;
    default "0";
    description
      "The zero-based-counter64 type represents a counter64 that
       has the defined 'initial' value zero.

       A data tree node using this type will be set to zero (0)
       on creation and will thereafter increase monotonically until
       it reaches a maximum value of 2^64-1 (18446744073709551615
       decimal), when it wraps around and starts increasing again
       from zero.

       Provided that an application discovers a new data tree node
       using this type within the minimum time to wrap, it can use
       the 'initial' value as a delta.  It is important for a
       management station to be aware of this minimum time and the
       actual time between polls, and to discard data if the actual
       time is too long or there is no defined minimum time.

       In the value set and its semantics, this type is equivalent
       to the ZeroBasedCounter64 textual convention of the SMIv2.";
    reference
      "RFC 2856: Textual Conventions for Additional High Capacity
                 Data Types";
  }

  typedef gauge32 {
    type uint32;
    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
       cannot be greater than 2^32-1 (4294967295 decimal), and
       the minimum value cannot 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
       the maximum value, the gauge32 also decreases; likewise, if
       the information increases above the minimum value, the
       gauge32 also increases.

       In the value set and its semantics, this type is equivalent
       to the Gauge32 type of the SMIv2.";
    reference
      "RFC 2578: Structure of Management Information Version 2
                 (SMIv2)";
  }

  typedef gauge64 {
    type uint64;
    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
       cannot be greater than 2^64-1 (18446744073709551615), and
       the minimum value cannot 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).

       In the value set and its semantics, this type is equivalent
       to the CounterBasedGauge64 SMIv2 textual convention defined
       in RFC 2856";
    reference
      "RFC 2856: Textual Conventions for Additional High Capacity
                 Data Types";
  }

  /*** collection of identifier-related types ***/

  typedef object-identifier {
    type string {
      pattern '(([0-1](\.[1-3]?[0-9]))|(2\.(0|([1-9][0-9]*))))'
            + '(\.(0|([1-9][0-9]*)))*';
    }
    description
      "The object-identifier type represents administratively
       assigned names in a registration-hierarchical-name tree.

       Values of this type are denoted as a sequence of numerical
       non-negative sub-identifier values.  Each sub-identifier
       value MUST NOT exceed 2^32-1 (4294967295).  Sub-identifiers
       are separated by single dots and without any intermediate
       whitespace.

       The ASN.1 standard restricts the value space of the first
       sub-identifier to 0, 1, or 2.  Furthermore, the value space
       of the second sub-identifier is restricted to the range
       0 to 39 if the first sub-identifier is 0 or 1.  Finally,
       the ASN.1 standard requires that an object identifier
       has always at least two sub-identifiers.  The pattern
       captures these restrictions.

       Although the number of sub-identifiers is not limited,
       module designers should realize that there may be
       implementations that stick with the SMIv2 limit of 128
       sub-identifiers.

       This type is a superset of the SMIv2 OBJECT IDENTIFIER type
       since it is not restricted to 128 sub-identifiers.  Hence,
       this type SHOULD NOT be used to represent the SMIv2 OBJECT
       IDENTIFIER type; the object-identifier-128 type SHOULD be
       used instead.";
    reference
      "ISO 9834-1: Information technology -- Procedures for the
       operation of object identifier registration authorities --
       Part 1: General procedures and top arcs of the international
       object identifier tree";
  }

  typedef object-identifier-128 {
    type object-identifier {
      pattern '[0-9]*(\.[0-9]*){1,127}';
    }
    description
      "This type represents object-identifiers restricted to 128
       sub-identifiers.

       In the value set and its semantics, this type is equivalent
       to the OBJECT IDENTIFIER type of the SMIv2.";
    reference
      "RFC 2578: Structure of Management Information Version 2
                 (SMIv2)";
  }

  /*** collection of types related to date and time ***/

  typedef date-and-time {
    type string {
      pattern
        '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])'
      + 'T(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
      + '(\.[0-9]+)?'
      + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
    }
    description
      "The date-and-time type is a profile of the ISO 8601
       standard for representation of dates and times using the
       Gregorian calendar.  The profile is defined by the
       date-time production in Section 5.6 of RFC 3339 and the
       update defined in Section 2 of RFC 9557.  The value of
       60 for seconds is allowed only in the case of leap seconds.

       The date-and-time type is compatible with the dateTime XML
       schema dateTime type with the following notable exceptions:

       (a) The date-and-time type does not allow negative years.

       (b) The time-offset Z indicates that the date-and-time
           value is reported in UTC and that the local time zone
           reference point is unknown.  The time-offset +00:00
           indicates that the date-and-time value is reported in
           UTC and that the local time zone reference point is UTC
           (see Section 2 of RFC 9557).

       This type is not equivalent to the DateAndTime textual
       convention of the SMIv2 since RFC 3339 uses a different
       separator between full-date and full-time and provides
       higher resolution of time-secfrac.

       The canonical format for date-and-time values with a known
       time zone uses a numeric time zone offset that is calculated
       using the device's configured known offset to UTC time.  A
       change of the device's offset to UTC time will cause
       date-and-time values to change accordingly.  Such changes
       might happen periodically if a server automatically follows
       daylight saving time (DST) time zone offset changes.  The
       canonical format for date-and-time values reported in UTC
       with an unknown local time zone offset SHOULD use the
       time-offset Z and MAY use -00:00 for backwards
       compatibility.";
    reference
      "ISO 8601: Data elements and interchange formats -- Information
                 interchange -- Representation of dates and times
       RFC 3339: Date and Time on the Internet: Timestamps
       RFC 9557: Date and Time on the Internet: Timestamps
                 with Additional Information
       RFC 2579: Textual Conventions for SMIv2
       XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                  Part 2: Datatypes";
  }

  typedef date {
    type string {
      pattern '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])'
            + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
    }
    description
      "The date type represents a time-interval of the length
       of a day, i.e., 24 hours.  It includes an optional time
       zone offset.

       The date type is compatible with the XML schema date
       type with the following notable exceptions:

       (a) The date type does not allow negative years.

       (b) The time-offset Z indicates that the date value is
           reported in UTC and that the local time zone reference
           point is unknown.  The time-offset +00:00 indicates that
           the date value is reported in UTC and that the local
           time zone reference point is UTC (see Section 2 of
           RFC 9557).

       The canonical format for date values with a known time
       zone uses a numeric time zone offset that is calculated using
       the device's configured known offset to UTC time.  A change of
       the device's offset to UTC time will cause date values
       to change accordingly.  Such changes might happen periodically
       if a server automatically follows daylight saving time
       (DST) time zone offset changes.  The canonical format for
       date values reported in UTC with an unknown local time zone
       offset uses the time-offset Z.";
    reference
      "RFC 3339: Date and Time on the Internet: Timestamps
       RFC 9557: Date and Time on the Internet: Timestamps
                 with Additional Information
       XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                  Part 2: Datatypes";
  }

  typedef date-no-zone {
    type date {
      pattern '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])';
    }
    description
      "The date-no-zone type represents a date without the optional
       time zone offset information.";
  }

  typedef time {
    type string {
      pattern
        '(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
      + '(\.[0-9]+)?'
      + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
    }
    description
      "The time type represents an instance of time of zero duration
       that recurs every day.  It includes an optional time zone
       offset.  The value of 60 for seconds is allowed only in the
       case of leap seconds.

       The time type is compatible with the XML schema time
       type with the following notable exception:

       (a) The time-offset Z indicates that the time value is
           reported in UTC and that the local time zone reference
           point is unknown.  The time-offset +00:00 indicates that
           the time value is reported in UTC and that the local
           time zone reference point is UTC (see Section 2 of
           RFC 9557).

       The canonical format for time values with a known time
       zone uses a numeric time zone offset that is calculated using
       the device's configured known offset to UTC time.  A change of
       the device's offset to UTC time will cause time values
       to change accordingly.  Such changes might happen periodically
       if a server automatically follows daylight saving time
       (DST) time zone offset changes.  The canonical format for
       time values reported in UTC with an unknown local time zone
       offset uses the time-offset Z.";
    reference
      "RFC 3339: Date and Time on the Internet: Timestamps
       RFC 9557: Date and Time on the Internet: Timestamps
                 with Additional Information
       XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                  Part 2: Datatypes";
  }

  typedef time-no-zone {
    type time {
      pattern
        '(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
      + '(\.[0-9]+)?';
    }
    description
      "The time-no-zone type represents a time without the optional
       time zone offset information.";
  }

  typedef hours32 {
    type int32;
    units "hours";
    description
      "A period of time measured in units of hours.

       The maximum time period that can be expressed is in the
       range [-89478485 days 08:00:00 to 89478485 days 07:00:00].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef minutes32 {
    type int32;
    units "minutes";
    description
      "A period of time measured in units of minutes.

       The maximum time period that can be expressed is in the
       range [-1491308 days 2:08:00 to 1491308 days 2:07:00].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef seconds32 {
    type int32;
    units "seconds";
    description
      "A period of time measured in units of seconds.

       The maximum time period that can be expressed is in the
       range [-24855 days 03:14:08 to 24855 days 03:14:07].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef centiseconds32 {
    type int32;
    units "centiseconds";
    description
      "A period of time measured in units of 10^-2 seconds.

       The maximum time period that can be expressed is in the
       range [-248 days 13:13:56 to 248 days 13:13:56].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef milliseconds32 {
    type int32;
    units "milliseconds";
    description
      "A period of time measured in units of 10^-3 seconds.

       The maximum time period that can be expressed is in the
       range [-24 days 20:31:23 to 24 days 20:31:23].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef microseconds32 {
    type int32;
    units "microseconds";
    description
      "A period of time measured in units of 10^-6 seconds.

       The maximum time period that can be expressed is in the
       range [-00:35:47 to 00:35:47].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef microseconds64 {
    type int64;
    units "microseconds";
    description
      "A period of time measured in units of 10^-6 seconds.

       The maximum time period that can be expressed is in the
       range [-106751991 days 04:00:54 to 106751991 days 04:00:54].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef nanoseconds32 {
    type int32;
    units "nanoseconds";
    description
      "A period of time measured in units of 10^-9 seconds.

       The maximum time period that can be expressed is in the
       range [-00:00:02 to 00:00:02].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef nanoseconds64 {
    type int64;
    units "nanoseconds";
    description
      "A period of time measured in units of 10^-9 seconds.

       The maximum time period that can be expressed is in the
       range [-106753 days 23:12:44 to 106752 days 0:47:16].

       This type should be range-restricted in situations
       where only non-negative time periods are desirable
       (i.e., range '0..max').";
  }

  typedef timeticks {
    type uint32;
    description
      "The timeticks type represents a non-negative integer that
       represents the time, modulo 2^32 (4294967296 decimal), in
       hundredths of a second between two epochs.  When a schema
       node is defined that uses this type, the description of
       the schema node identifies both of the reference epochs.

       In the value set and its semantics, this type is equivalent
       to the TimeTicks type of the SMIv2.";
    reference
      "RFC 2578: Structure of Management Information Version 2
                 (SMIv2)";
  }

  typedef timestamp {
    type timeticks;
    description
      "The timestamp type represents the value of an associated
       timeticks schema node instance at which a specific occurrence
       happened.  The specific occurrence must be defined in the
       description of any schema node defined using this type.  When
       the specific occurrence occurred prior to the last time the
       associated timeticks schema node instance was zero, then the
       timestamp value is zero.

       Note that this requires all timestamp values to be reset to
       zero when the value of the associated timeticks schema node
       instance reaches 497+ days and wraps around to zero.

       The associated timeticks schema node must be specified
       in the description of any schema node using this type.

       In the value set and its semantics, this type is equivalent
       to the TimeStamp textual convention of the SMIv2.";
    reference
      "RFC 2579: Textual Conventions for SMIv2";
  }

  /*** collection of generic address types ***/

  typedef phys-address {
    type string {
      pattern '([0-9a-fA-F]{2}(:[0-9a-fA-F]{2})*)?';
    }
    description
      "Represents media- or physical-level addresses represented
       as a sequence of octets, each octet represented by two
       hexadecimal numbers.  Octets are separated by colons.  The
       canonical representation uses lowercase characters.

       In the value set and its semantics, this type is equivalent
       to the PhysAddress textual convention of the SMIv2.";
    reference
      "RFC 2579: Textual Conventions for SMIv2";
  }

  typedef mac-address {
    type string {
      pattern '[0-9a-fA-F]{2}(:[0-9a-fA-F]{2}){5}';
    }
    description
      "The mac-address type represents a 48-bit IEEE 802 Media
       Access Control (MAC) address.  The canonical representation
       uses lowercase characters.  Note that there are IEEE 802 MAC
       addresses with a different length that this type cannot
       represent.  The phys-address type may be used to represent
       physical addresses of varying length.

       In the value set and its semantics, this type is equivalent
       to the MacAddress textual convention of the SMIv2.";
    reference
      "IEEE 802: IEEE Standard for Local and Metropolitan Area
                 Networks: Overview and Architecture
       RFC 2579: Textual Conventions for SMIv2";
  }

  /*** collection of XML-specific types ***/

  typedef xpath1.0 {
    type string;
    description
      "This type represents an XPATH 1.0 expression.

       When a schema node is defined that uses this type, the
       description of the schema node MUST specify the XPath
       context in which the XPath expression is evaluated.";
    reference
      "XPATH: XML Path Language (XPath) Version 1.0";
  }

  /*** collection of string types ***/

  typedef hex-string {
    type string {
      pattern '([0-9a-fA-F]{2}(:[0-9a-fA-F]{2})*)?';
    }
    description
      "A hexadecimal string with octets represented as hex digits
       separated by colons.  The canonical representation uses
       lowercase characters.";
  }

  typedef uuid {
    type string {
      pattern '[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-'
            + '[0-9a-fA-F]{4}-[0-9a-fA-F]{12}';
    }
    description
      "A Universally Unique IDentifier in the string representation
       defined in RFC 9562.  The canonical representation uses
       lowercase characters.

       The following is an example of a UUID in string
       representation:
       f81d4fae-7dec-11d0-a765-00a0c91e6bf6.
      ";
    reference
      "RFC 9562: Universally Unique IDentifiers (UUIDs)";
  }

  typedef dotted-quad {
    type string {
      pattern
        '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
      + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])';
    }
    description
      "An unsigned 32-bit number expressed in the dotted-quad
       notation, i.e., four octets written as decimal numbers
       and separated with the '.' (full stop) character.";
  }

  typedef language-tag {
    type string;
    description
      "A language tag according to RFC 5646 (BCP 47).  The
       canonical representation uses lowercase characters.

       Values of this type must be well-formed language tags,
       in conformance with the definition of well-formed tags
       in BCP 47.  Implementations MAY further limit the values
       they accept to those permitted by a 'validating'
       processor, as defined in BCP 47.

       The canonical representation of values of this type is
       aligned with the SMIv2 LangTag textual convention for
       language tags fitting the length constraints imposed
       by the LangTag textual convention.";
    reference
      "RFC 5646: Tags for Identifying Languages
       RFC 5131: A MIB Textual Convention for Language Tags";
  }

  /*** collection of YANG-specific types ***/

  typedef yang-identifier {
    type string {
      length "1..max";
      pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*';
    }
    description
      "A YANG identifier string as defined by the 'identifier'
       rule in Section 14 of RFC 7950.  An identifier must
       start with an alphabetic character or an underscore
       followed by an arbitrary sequence of alphabetic or
       numeric characters, underscores, hyphens, or dots.

       This definition conforms to YANG 1.1 defined in RFC
       7950.  In RFC 6991, this definition excluded
       all identifiers starting with any possible combination
       of the lowercase or uppercase character sequence 'xml',
       as required by YANG 1 defined in RFC 6020.  If this type
       is used in a YANG 1 context, then this restriction still
       applies.";
    reference
      "RFC 7950: The YANG 1.1 Data Modeling Language
       RFC 6991: Common YANG Data Types
       RFC 6020: YANG - A Data Modeling Language for the
                 Network Configuration Protocol (NETCONF)";
  }
}

Internet Protocol Suite Types
The "ietf-inet-types" YANG module references [RFC0768], [RFC0791], [RFC0952], [RFC1034], [RFC1123], [RFC1930], [RFC2317], [RFC2474], [RFC2780], [RFC2782], [RFC3289], [RFC3305], [RFC3595], [RFC3927], [RFC3986], [RFC4001], [RFC4007], [RFC4271], [RFC4291], [RFC4340], [RFC4592], [RFC5017], [RFC5322], [RFC5890], [RFC5952], [RFC6532], [RFC6793], [RFC8200], [RFC9260], [RFC9293], and [RFC9499].

module ietf-inet-types {
  namespace "urn:ietf:params:xml:ns:yang:ietf-inet-types";
  prefix inet;

  organization
    "IETF Network Modeling (NETMOD) Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
     WG List:  <mailto:netmod@ietf.org>

     Editor:   Jürgen Schönwälder
               <mailto:jschoenwaelder@constructor.university>";
  description
    "This module contains a collection of generally useful derived
     YANG data types for Internet addresses and related things.

     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 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.

     Copyright (c) 2025 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 Revised BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9911;
     see the RFC itself for full legal notices.";

  revision 2025-12-01 {
    description
      "This revision adds the following new data types:
       - inet:ip-address-and-prefix
       - inet:ipv4-address-and-prefix
       - inet:ipv6-address-and-prefix
       - inet:protocol-number
       - inet:upper-layer-protocol-number
       - inet:host-name
       - inet:email-address
       - inet:ip-address-link-local
       - inet:ipv4-address-link-local
       - inet:ipv6-address-link-local
       The inet:host union was changed to use inet:host-name instead
       of inet:domain-name.  Several pattern statements have been
       improved.";
    reference
      "RFC 9911: Common YANG Data Types";
  }
  revision 2013-07-15 {
    description
      "This revision adds the following new data types:
       - inet:ip-address-no-zone
       - inet:ipv4-address-no-zone
       - inet:ipv6-address-no-zone";
    reference
      "RFC 6991: Common YANG Data Types";
  }
  revision 2010-09-24 {
    description
      "Initial revision.";
    reference
      "RFC 6021: Common YANG Data Types";
  }

  /*** collection of types related to protocol fields ***/

  typedef ip-version {
    type enumeration {
      enum unknown {
        value 0;
        description
          "An unknown or unspecified version of the Internet
           Protocol.";
      }
      enum ipv4 {
        value 1;
        description
          "The IPv4 protocol as defined in RFC 791.";
      }
      enum ipv6 {
        value 2;
        description
          "The IPv6 protocol as defined in RFC 8200.";
      }
    }
    description
      "This value represents the version of the Internet Protocol.

       In the value set and its semantics, this type is equivalent
       to the InetVersion textual convention of the SMIv2.";
    reference
      "RFC  791: Internet Protocol
       RFC 8200: Internet Protocol, Version 6 (IPv6) Specification
       RFC 4001: Textual Conventions for Internet Network Addresses";
  }

  typedef dscp {
    type uint8 {
      range "0..63";
    }
    description
      "The dscp type represents a Differentiated Services Code Point
       that may be used for marking packets in a traffic stream.

       In the value set and its semantics, this type is equivalent
       to the Dscp textual convention of the SMIv2.";
    reference
      "RFC 3289: Management Information Base for the Differentiated
                 Services Architecture
       RFC 2474: Definition of the Differentiated Services Field
                 (DS Field) in the IPv4 and IPv6 Headers
       RFC 2780: IANA Allocation Guidelines For Values In
                 the Internet Protocol and Related Headers";
  }

  typedef ipv6-flow-label {
    type uint32 {
      range "0..1048575";
    }
    description
      "The ipv6-flow-label type represents the flow identifier or
       Flow Label in an IPv6 packet header that may be used to
       discriminate traffic flows.

       In the value set and its semantics, this type is equivalent
       to the IPv6FlowLabel textual convention of the SMIv2.";
    reference
      "RFC 3595: Textual Conventions for IPv6 Flow Label
       RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
  }

  typedef port-number {
    type uint16 {
      range "0..65535";
    }
    description
      "The port-number type represents a 16-bit port number of an
       Internet transport-layer protocol such as UDP, TCP, DCCP, or
       SCTP.

       Port numbers are assigned by IANA.  The current list of
       all assignments is available from <https://www.iana.org/>.

       Note that the port number value zero is reserved by IANA.  In
       situations where the value zero does not make sense, it can
       be excluded by subtyping the port-number type.

       In the value set and its semantics, this type is equivalent
       to the InetPortNumber textual convention of the SMIv2.";
    reference
      "RFC  768: User Datagram Protocol
       RFC 9293: Transmission Control Protocol (TCP)
       RFC 9260: Stream Control Transmission Protocol
       RFC 4340: Datagram Congestion Control Protocol (DCCP)
       RFC 4001: Textual Conventions for Internet Network Addresses";
  }

  typedef protocol-number {
    type uint8;
    description
      "The protocol-number type represents an 8-bit Internet
       Protocol number, carried in the 'protocol' field of the
       IPv4 header or in the 'next header' field of the IPv6
       header.

       Protocol numbers are assigned by IANA.  The current list of
       all assignments is available from <https://www.iana.org/>.";
    reference
      "RFC  791: Internet Protocol
       RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
  }

  typedef upper-layer-protocol-number {
    type protocol-number;
    description
      "The upper-layer-protocol-number represents the upper-layer
       protocol number carried in an IP packet.  For IPv6 packets
       with extension headers, this is the protocol number carried
       in the last 'next header' field of the chain of IPv6 extension
       headers.";
    reference
      "RFC  791: Internet Protocol
       RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
  }

  /*** collection of types related to autonomous systems ***/

  typedef as-number {
    type uint32;
    description
      "The as-number type represents autonomous system numbers
       that identify an Autonomous System (AS).  An AS is a set
       of routers under a single technical administration, using
       an interior gateway protocol and common metrics to route
       packets within the AS, and using an exterior gateway
       protocol to route packets to other ASes.  IANA maintains
       the autonomous system number space and has delegated large
       parts to the regional registries.

       Autonomous system numbers were originally limited to 16
       bits.  BGP extensions have enlarged the autonomous system
       number space to 32 bits.  This type therefore uses an uint32
       base type without a range restriction in order to support
       a larger autonomous system number space.

       In the value set and its semantics, this type is equivalent
       to the InetAutonomousSystemNumber textual convention of
       the SMIv2.";
    reference
      "RFC 1930: Guidelines for creation, selection, and registration
                 of an Autonomous System (AS)
       RFC 4271: A Border Gateway Protocol 4 (BGP-4)
       RFC 4001: Textual Conventions for Internet Network Addresses
       RFC 6793: BGP Support for Four-Octet Autonomous System (AS)
                 Number Space";
  }

  /*** collection of types related to IP addresses and hostnames ***/

  typedef ip-address {
    type union {
      type ipv4-address;
      type ipv6-address;
    }
    description
      "The ip-address type represents an IP address and is IP
       version neutral.  The format of the textual representation
       implies the IP version.  This type supports scoped addresses
       by allowing zone identifiers in the address format.";
    reference
      "RFC 4007: IPv6 Scoped Address Architecture";
  }

  typedef ipv4-address {
    type string {
      pattern
        '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
      + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
      + '(%.+)?';
    }
    description
      "The ipv4-address type represents an IPv4 address in
       dotted-quad notation.  The IPv4 address may include a zone
       index, separated by a % sign.  If a system uses zone names
       that are not represented in UTF-8, then an implementation
       needs to use some mechanism to transform the local name
       into UTF-8.  The definition of such a mechanism is outside
       the scope of this document.

       The zone index is used to disambiguate identical address
       values.  For link-local addresses, the zone index will
       typically be the interface index number or the name of an
       interface.  If the zone index is not present, the default
       zone of the device will be used.

       The canonical format for the zone index is the numerical
       format";
  }

  typedef ipv6-address {
    type string {
      pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
            + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
            + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
            + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
            + '(%[A-Za-z0-9][A-Za-z0-9\-\._~/]*)?';
      pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
            + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
            + '(%.+)?';
    }
    description
      "The ipv6-address type represents an IPv6 address in full,
       mixed, shortened, and shortened-mixed notation.  The IPv6
       address may include a zone index, separated by a % sign.
       If a system uses zone names that are not represented in
       UTF-8, then an implementation needs to use some mechanism
       to transform the local name into UTF-8.  The definition of
       such a mechanism is outside the scope of this document.

       The zone index is used to disambiguate identical address
       values.  For link-local addresses, the zone index will
       typically be the interface index number or the name of an
       interface.  If the zone index is not present, the default
       zone of the device will be used.

       The canonical format of IPv6 addresses uses the textual
       representation defined in Section 4 of RFC 5952.  The
       canonical format for the zone index is the numerical
       format as described in Section 11.2 of RFC 4007.";
    reference
      "RFC 4291: IP Version 6 Addressing Architecture
       RFC 4007: IPv6 Scoped Address Architecture
       RFC 5952: A Recommendation for IPv6 Address Text
                 Representation";
  }

  typedef ip-address-no-zone {
    type union {
      type ipv4-address-no-zone;
      type ipv6-address-no-zone;
    }
    description
      "The ip-address-no-zone type represents an IP address and is
       IP version neutral.  The format of the textual representation
       implies the IP version.  This type does not support scoped
       addresses since it does not allow zone identifiers in the
       address format.";
    reference
      "RFC 4007: IPv6 Scoped Address Architecture";
  }

  typedef ipv4-address-no-zone {
    type ipv4-address {
      pattern '[0-9\.]*';
    }
    description
      "An IPv4 address without a zone index.  This type, derived
       from the type ipv4-address, may be used in situations where
       the zone is known from the context and no zone index is
       needed.";
  }

  typedef ipv6-address-no-zone {
    type ipv6-address {
      pattern '[0-9a-fA-F:\.]*';
    }
    description
      "An IPv6 address without a zone index.  This type, derived
       from the type ipv6-address, may be used in situations where
       the zone is known from the context and no zone index is
       needed.";
    reference
      "RFC 4291: IP Version 6 Addressing Architecture
       RFC 4007: IPv6 Scoped Address Architecture
       RFC 5952: A Recommendation for IPv6 Address Text
                 Representation";
  }

  typedef ip-address-link-local {
    type union {
      type ipv4-address-link-local;
      type ipv6-address-link-local;
    }
    description
      "The ip-address-link-local type represents a link-local IP
       address and is IP version neutral.  The format of the textual
       representation implies the IP version.";
  }

  typedef ipv4-address-link-local {
    type ipv4-address {
      pattern '169\.254\..*';
    }
    description
      "The ipv4-address-link-local type represents a link-local IPv4
       address in the prefix 169.254.0.0/16 as defined in Section 2.1
       of RFC 3927.";
    reference
      "RFC 3927: Dynamic Configuration of IPv4 Link-Local Addresses";
  }

  typedef ipv6-address-link-local {
    type ipv6-address {
      pattern '[fF][eE][89aAbB][0-9a-fA-F]:.*';
    }
    description
      "The ipv6-address-link-local type represents a link-local IPv6
       address in the prefix fe80::/10 as defined in Section 2.4 of
       RFC 4291.";
    reference
      "RFC 4291: IP Version 6 Addressing Architecture";
  }

  typedef ip-prefix {
    type union {
      type ipv4-prefix;
      type ipv6-prefix;
    }
    description
      "The ip-prefix type represents an IP prefix and is IP
       version neutral.  The format of the textual representations
       implies the IP version.";
  }

  typedef ipv4-prefix {
    type string {
      pattern
        '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
      + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
      + '/(([0-9])|([1-2][0-9])|(3[0-2]))';
    }
    description
      "The ipv4-prefix type represents an IPv4 prefix.
       The prefix length is given by the number following the
       slash character and must be less than or equal to 32.

       A prefix length value of n corresponds to an IP address
       mask that has n contiguous 1-bits from the most
       significant bit (MSB) and all other bits set to 0.

       The canonical format of an IPv4 prefix has all bits of
       the IPv4 address set to zero that are not part of the
       IPv4 prefix.

       The definition of ipv4-prefix does not require that bits
       that are not part of the prefix be set to zero.  However,
       implementations have to return values in canonical format,
       which requires non-prefix bits to be set to zero.  This means
       that 192.0.2.1/24 must be accepted as a valid value, but it
       will be converted into the canonical format 192.0.2.0/24.";
  }

  typedef ipv6-prefix {
    type string {
      pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
            + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
            + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
            + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
            + '(/(([0-9])|([0-9]{2})|(1[0-1][0-9])|(12[0-8])))';
      pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
            + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
            + '(/.+)';
    }
    description
      "The ipv6-prefix type represents an IPv6 prefix.
       The prefix length is given by the number following the
       slash character and must be less than or equal to 128.

       A prefix length value of n corresponds to an IP address
       mask that has n contiguous 1-bits from the most
       significant bit (MSB) and all other bits set to 0.

       The canonical format of an IPv6 prefix has all bits of
       the IPv6 address set to zero that are not part of the
       IPv6 prefix.  Furthermore, the IPv6 address is represented
       as defined in Section 4 of RFC 5952.

       The definition of ipv6-prefix does not require that bits
       that are not part of the prefix be set to zero.  However,
       implementations have to return values in canonical format,
       which requires non-prefix bits to be set to zero.  This means
       that 2001:db8::1/64 must be accepted as a valid value, but it
       will be converted into the canonical format 2001:db8::/64.";
    reference
      "RFC 5952: A Recommendation for IPv6 Address Text
                 Representation";
  }

  typedef ip-address-and-prefix {
    type union {
      type ipv4-address-and-prefix;
      type ipv6-address-and-prefix;
    }
    description
      "The ip-address-and-prefix type represents an IP address and
       prefix and is IP version neutral.  The format of the textual
       representations implies the IP version.";
  }

  typedef ipv4-address-and-prefix {
    type string {
      pattern
        '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
      + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
      + '/(([0-9])|([1-2][0-9])|(3[0-2]))';
    }
    description
      "The ipv4-address-and-prefix type represents an IPv4
       address and an associated IPv4 prefix.
       The prefix length is given by the number following the
       slash character and must be less than or equal to 32.

       A prefix length value of n corresponds to an IP address
       mask that has n contiguous 1-bits from the most
       significant bit (MSB) and all other bits set to 0.";
  }

  typedef ipv6-address-and-prefix {
    type string {
      pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
            + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
            + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
            + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
            + '(/(([0-9])|([0-9]{2})|(1[0-1][0-9])|(12[0-8])))';
      pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
            + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
            + '(/.+)';
    }
    description
      "The ipv6-address-and-prefix type represents an IPv6
       address and an associated IPv6 prefix.
       The prefix length is given by the number following the
       slash character and must be less than or equal to 128.

       A prefix length value of n corresponds to an IP address
       mask that has n contiguous 1-bits from the most
       significant bit (MSB) and all other bits set to 0.

       The canonical format requires that the IPv6 address is
       represented as defined in Section 4 of RFC 5952.";
    reference
      "RFC 5952: A Recommendation for IPv6 Address Text
                 Representation";
  }

  /*** collection of domain name and URI types ***/

  typedef domain-name {
    type string {
      length "1..253";
      pattern
        '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.)*'
      + '([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?)'
      + '|\.';
    }
    description
      "The domain-name type represents a DNS domain name.  The
       name SHOULD be fully qualified whenever possible.  This
       type does not support wildcards (see RFC 4592) or
       classless in-addr.arpa delegations (see RFC 2317).

       Internet domain names are only loosely specified.  Section
       3.5 of RFC 1034 recommends a syntax (modified in Section
       2.1 of RFC 1123).  The pattern above is intended to allow
       for current practice in domain name use and some possible
       future expansion.  Note that Internet host names have a
       stricter syntax (described in RFC 952) than the DNS
       recommendations in RFCs 1034 and 1123.  Schema nodes
       representing host names should use the host-name type
       instead of the domain-type.

       The encoding of DNS names in the DNS protocol is limited
       to 255 characters.  Since the encoding consists of labels
       prefixed by a length byte and there is a trailing NUL
       byte, only 253 characters can appear in the textual dotted
       notation.

       The description clause of schema nodes using the domain-name
       type MUST describe when and how these names are resolved to
       IP addresses.  Note that the resolution of a domain-name value
       may require to query multiple DNS records (e.g., A for IPv4
       and AAAA for IPv6).  The order of the resolution process and
       which DNS record takes precedence can either be defined
       explicitly or depend on the configuration of the
       resolver.

       Domain-name values use the ASCII encoding.  Their canonical
       format uses lowercase ASCII characters.  Internationalized
       domain names MUST be A-labels as per RFC 5890.";
    reference
      "RFC  952: DoD Internet Host Table Specification
       RFC 1034: Domain Names - Concepts and Facilities
       RFC 1123: Requirements for Internet Hosts -- Application
                 and Support
       RFC 2317: Classless IN-ADDR.ARPA delegation
       RFC 2782: A DNS RR for specifying the location of services
                 (DNS SRV)
       RFC 4592: The Role of Wildcards in the Domain Name System
       RFC 5890: Internationalized Domain Names in Applications
                 (IDNA): Definitions and Document Framework
       RFC 9499: DNS Terminology";
  }

  typedef host-name {
    type domain-name {
      length "2..max";
      pattern '[a-zA-Z0-9\-\.]+';
    }
    description
      "The host-name type represents fully qualified host names.
       Host names must be at least two characters long (see RFC 952),
       and they are restricted to labels consisting of letters,
       digits, and hyphens separated by dots (see RFCs 1123 and
       952).";
    reference
      "RFC  952: DoD Internet Host Table Specification
       RFC 1123: Requirements for Internet Hosts -- Application
                 and Support";
  }

  typedef host {
    type union {
      type ip-address;
      type host-name;
    }
    description
      "The host type represents either an IP address or a fully
       qualified host name.";
  }

  typedef uri {
    type string {
      pattern '[a-z][a-z0-9+.-]*:.*';
    }
    description
      "The uri type represents a Uniform Resource Identifier
       (URI) as defined by the rule 'URI' in RFC 3986.

       Objects using the uri type MUST be in ASCII encoding
       and MUST be normalized as described in Sections 6.2.1,
       6.2.2.1, and 6.2.2.2 of RFC 3986.  Characters that can be
       represented without using percent-encoding are represented
       as characters (without percent-encoding), and all
       case-insensitive characters are set to lowercase except
       for hexadecimal digits within a percent-encoded triplet,
       which are normalized to uppercase as described in
       Section 6.2.2.1 of RFC 3986.

       The purpose of this normalization is to help provide
       unique URIs.  Note that this normalization is not
       sufficient to provide uniqueness.  Two URIs that are
       textually distinct after this normalization may still be
       equivalent.

       Objects using the uri type may restrict the schemes that
       they permit.  For example, 'data:' and 'urn:' schemes
       might not be appropriate.

       A zero-length URI is not a valid URI.  This can be used to
       express 'URI absent' where required.

       In the value set and its semantics, this type is equivalent
       to the Uri SMIv2 textual convention defined in RFC 5017.";
    reference
      "RFC 3986: Uniform Resource Identifier (URI): Generic Syntax
       RFC 3305: Report from the Joint W3C/IETF URI Planning Interest
                 Group: Uniform Resource Identifiers (URIs), URLs,
                 and Uniform Resource Names (URNs): Clarifications
                 and Recommendations
       RFC 5017: MIB Textual Conventions for Uniform Resource
                 Identifiers (URIs)";
  }

  typedef email-address {
    type string {
      pattern '.+@.+';
    }
    description
      "The email-address type represents an internationalized
       email address.

       The email address format is defined by the addr-spec
       ABNF rule in Section 3.4.1 of RFC 5322.  This format has
       been extended by RFC 6532 to support internationalized
       email addresses.  Implementations MUST support the
       internationalization extensions of RFC 6532.  Support
       for the obsolete obs-local-part, obs-domain, and
       obs-qtext in RFC 5322 is not required.

       The domain part may use both A-labels and U-labels
       (see RFC 5890).  The canonical format of the domain part
       uses lowercase characters and U-labels (RFC 5890) where
       applicable.";
    reference
      "RFC 5322: Internet Message Format
       RFC 5890: Internationalized Domain Names in Applications
                 (IDNA): Definitions and Document Framework
       RFC 6532: Internationalized Email Headers";
  }
}

IANA Considerations
This document reuses the URIs for "ietf-yang-types" and "ietf-inet-types" in the "IETF XML Registry" [RFC3688].
Per this document, IANA has updated the "YANG Module Names" registry to reference this RFC instead of [RFC6991] for the "ietf-yang-types" and "ietf-inet-types" modules. Following the format in [RFC6020], these registrations have been made.
Name:
ietf-yang-types
Namespace:
urn:ietf:params:xml:ns:yang:ietf-yang-types
Prefix:
yang
Reference:
RFC 9911
Name:
ietf-inet-types
Namespace:
urn:ietf:params:xml:ns:yang:ietf-inet-types
Prefix:
inet
Reference:
RFC 9911
Security Considerations
This document defines common data types using the YANG data modeling language. The definitions themselves have no security impact on the Internet, but the usage of these definitions in concrete YANG modules might have. The security considerations spelled out in the YANG specification [RFC7950] apply for this document as well.
References
Normative References
[XPATH]

XML Path Language (XPath) Version 1.0
James Clark, Ed.
Steve DeRose, Ed.
16 November 1999
W3C Recommendation
[XSD-TYPES]

W3C XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes
David Peterson, Ed.
Shudi Gao, Ed.
Ashok Malhotra, Ed.
C.M. Sperberg-McQueen, Ed.
Henry S. Thompson, Ed.
5 April 2012
W3C Recommendation
Informative References
[ISO-8601]

Data elements and interchange formats -- Information interchange -- Representation of dates and times
ISO/IEC
December 2008
ISO/IEC 8601:2000
[ISO-9834-1]

Information technology -- Procedures for the operation of object identifier registration authorities -- Part 1: General procedures and top arcs of the international object identifier tree
ISO/IEC
2012
ISO/IEC 9834-1:2012
[IEEE-802-2024]

IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture
IEEE
2025-03
IEEE Std 802-2024
DOI 10.1109/IEEESTD.2025.10935844
[Err4076]

Erratum ID 4076
RFC Errata
RFC 6991
[Err5105]

Erratum ID 5105
RFC Errata
RFC 6991
[RFC7950]
[RFC6241]
[RFC6021]
[RFC6991]
[RFC2119]
[RFC8174]
[RFC2578]
[RFC2579]
[RFC2856]
[RFC3339]
[RFC4502]
[RFC5131]
[RFC5646]
[RFC9557]
[RFC9562]
[RFC0768]
[RFC0791]
[RFC0952]
[RFC1034]
[RFC1123]
[RFC1930]
[RFC2317]
[RFC2474]
[RFC2780]
[RFC2782]
[RFC3289]
[RFC3305]
[RFC3595]
[RFC3927]
[RFC3986]
[RFC4001]
[RFC4007]
[RFC4271]
[RFC4291]
[RFC4340]
[RFC4592]
[RFC5017]
[RFC5322]
[RFC5890]
[RFC5952]
[RFC6532]
[RFC6793]
[RFC8200]
[RFC9260]
[RFC9293]
[RFC9499]
[RFC3688]
[RFC6020]
Acknowledgments
The following people contributed significantly to the original version of this document, which was published as [RFC6021]: Andy Bierman, Martin Björklund, Balazs Lengyel, David Partain, and Phil Shafer.
Helpful comments on various draft versions of this document were provided by the following individuals: Andy Bierman, Martin Björklund, Benoît Claise, Joel M. Halpern, Ladislav Lhotka, Lars-Johan Liman, and Dan Romascanu.