Textual Conventions for Internet Network Addresses

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright © The Internet Society (2002). All Rights Reserved.

Abstract

This MIB module defines textual conventions to represent commonly used Internet network layer addressing information. The intent is that these textual conventions (TCs) will be imported and used in MIB modules that would otherwise define their own representations.

This document obsoletes RFC 2851.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  The SNMP Management Framework  . . . . . . . . . . . . . . . .  4
   3.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Usage Hints  . . . . . . . . . . . . . . . . . . . . . . . . . 11
   4.1 Table Indexing . . . . . . . . . . . . . . . . . . . . . . . . 12
   4.2 Uniqueness of Addresses  . . . . . . . . . . . . . . . . . . . 12
   4.3 Multiple Addresses per Host  . . . . . . . . . . . . . . . . . 13
   4.4 Resolving DNS Names  . . . . . . . . . . . . . . . . . . . . . 13
   5.  Table Indexing Example . . . . . . . . . . . . . . . . . . . . 13
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Intellectual Property Notice . . . . . . . . . . . . . . . . . 16
   9.  Changes from RFC 2851  . . . . . . . . . . . . . . . . . . . . 16
   References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 20

1. Introduction

Several standards-track MIB modules use the IpAddress SMIv2 base type. This limits the applicability of these MIB modules to IP Version 4 (IPv4) since the IpAddress SMIv2 base type can only contain 4 byte IPv4 addresses. The IpAddress SMIv2 base type has become problematic with the introduction of IP Version 6 (IPv6) addresses [19].

This document defines multiple textual conventions as a mechanism to express generic Internet network layer addresses within MIB module specifications. The solution is compatible with SMIv2 (STD 58) and SMIv1 (STD 16). New MIB definitions which need to express network layer Internet addresses SHOULD use the textual conventions defined in this memo. New MIB modules SHOULD NOT use the SMIv2 IpAddress base type anymore.

A generic Internet address consists of two objects, one whose syntax is InetAddressType, and another whose syntax is InetAddress. The value of the first object determines how the value of the second object is encoded. The InetAddress textual convention represents an opaque Internet address value. The InetAddressType enumeration is used to "cast" the InetAddress value into a concrete textual convention for the address type. This usage of multiple textual conventions allows expression of the display characteristics of each address type and makes the set of defined Internet address types extensible.

The textual conventions defined in this document can also be used to represent generic Internet subnets and Internet address ranges. A generic Internet subnet is represented by three objects, one whose syntax is InetAddressType, a second one whose syntax is InetAddress and a third one whose syntax is InetAddressPrefixLength. The InetAddressType value again determines the concrete format of the InetAddress value while the InetAddressPrefixLength identifies the Internet network address prefix.

A generic range of consecutive Internet addresses is represented by three objects. The first one has the syntax InetAddressType while the remaining objects have the syntax InetAddress and specify the start and end of the address range. The InetAddressType value again determines the format of the InetAddress values.

The textual conventions defined in this document can be used to define Internet addresses by using DNS domain names in addition to IPv4 and IPv6 addresses. A MIB designer can write compliance statements to express that only a subset of the possible address types must be supported by a compliant implementation.

MIB developers who need to represent Internet addresses SHOULD use these definitions whenever applicable, as opposed to defining their own constructs. Even MIB modules that only need to represent IPv4 or IPv6 addresses SHOULD use the InetAddressType/InetAddress textual conventions defined in this memo.

There are many widely deployed MIB modules that use IPv4 addresses and which need to be revised to support IPv6. These MIBs can be categorized as follows:

1. MIB modules which define management information that is in principle IP version neutral, but the MIB currently uses addressing constructs specific to a certain IP version.

2. MIB modules which define management information that is specific to particular IP version (either IPv4 or IPv6) and which is very unlikely to ever be applicable to another IP version.

MIB modules of the first type SHOULD provide object definitions (e.g., tables) that work with all versions of IP. In particular, when revising a MIB module which contains IPv4 specific tables, it is suggested to define new tables using the textual conventions defined in this memo which support all versions of IP. The status of the new tables SHOULD be "current" while the status of the old IP version specific tables SHOULD be changed to "deprecated". The other approach of having multiple similar tables for different IP versions is strongly discouraged.

MIB modules of the second type, which are inherently IP version specific, do not need to be redefined. Note that even in this case, any additions to these MIB modules or new IP version specific MIB modules SHOULD use the textual conventions defined in this memo.

MIB developers SHOULD NOT use the textual conventions defined in this document to represent generic transport layer addresses. Instead the SMIv2 TAddress textual convention and associated definitions should be used for transport layer addresses.

The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT" and "MAY" in this document are to be interpreted as described in RFC 2119 [1].

2. The SNMP Management Framework

The SNMP Management Framework presently consists of five major components:

• An overall architecture, described in RFC 2571 [2].

• Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and described in STD 16, RFC 1155 [3], STD 16, RFC 1212 [4] and RFC 1215 [5]. The second version, called SMIv2, is described in STD 58, RFC 2578 [6], STD 58, RFC 2579 [7] and STD 58, RFC 2580 [8].

• Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in STD 15, RFC 1157 [9]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [10] and RFC 1906 [11]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [11], RFC 2572 [12] and RFC 2574 [13].

• Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [9]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [14].

• A set of fundamental applications described in RFC 2573 [15] and the view-based access control mechanism described in RFC 2575 [16].

A more detailed introduction to the current SNMP Management Framework can be found in RFC 2570 [17].

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the mechanisms defined in the SMI.

This memo specifies a MIB module that is compliant to the SMIv2. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (use of Counter64). Some machine readable information in SMIv2 will be converted into textual descriptions in SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the MIB.

3. Definitions

INET-ADDRESS-MIB DEFINITIONS ::= BEGIN

IMPORTS

    MODULE-IDENTITY, mib-2, Unsigned32 FROM SNMPv2-SMI
    TEXTUAL-CONVENTION                 FROM SNMPv2-TC;

inetAddressMIB MODULE-IDENTITY

    LAST-UPDATED "200205090000Z"
    ORGANIZATION
        "IETF Operations and Management Area"
    CONTACT-INFO
        "Juergen Schoenwaelder (Editor)
         TU Braunschweig
         Bueltenweg 74/75
         38106 Braunschweig, Germany
    
         Phone: +49 531 391-3289
         EMail: schoenw@ibr.cs.tu-bs.de
    
         Send comments to <mibs@ops.ietf.org>."
    DESCRIPTION
        "This MIB module defines textual conventions for
         representing Internet addresses. An Internet
         address can be an IPv4 address, an IPv6 address
         or a DNS domain name. This module also defines
         textual conventions for Internet port numbers,
         autonomous system numbers and the length of an
         Internet address prefix."
    REVISION     "200205090000Z"
    DESCRIPTION
        "Second version, published as RFC 3291. This
         revisions contains several clarifications and it
         introduces several new textual conventions:
         InetAddressPrefixLength, InetPortNumber,
         InetAutonomousSystemNumber, InetAddressIPv4z,
         and InetAddressIPv6z."
    REVISION     "200006080000Z"
    DESCRIPTION
        "Initial version, published as RFC 2851."
    ::= { mib-2 76 }

InetAddressType ::= TEXTUAL-CONVENTION

    STATUS      current
    DESCRIPTION
        "A value that represents a type of Internet address.
         unknown(0)  An unknown address type. This value MUST
                     be used if the value of the corresponding
                     InetAddress object is a zero-length string.
                     It may also be used to indicate an IP address
                     which is not in one of the formats defined
                     below.
    
         ipv4(1)     An IPv4 address as defined by the
                     InetAddressIPv4 textual convention.
    
         ipv6(2)     A global IPv6 address as defined by the
                     InetAddressIPv6 textual convention.
    
         ipv4z(3)    A non-global IPv4 address including a zone
                     index as defined by the InetAddressIPv4z
                     textual convention.
    
         ipv6z(4)    A non-global IPv6 address including a zone
                     index as defined by the InetAddressIPv6z
                     textual convention.
    
         dns(16)     A DNS domain name as defined by the
                     InetAddressDNS textual convention.

Each definition of a concrete InetAddressType value must be accompanied by a definition of a textual convention for use with that InetAddressType.

To support future extensions, the InetAddressType textual convention SHOULD NOT be sub-typed in object type definitions. It MAY be sub-typed in compliance statements in order to require only a subset of these address types for a compliant implementation.

Implementations must ensure that InetAddressType objects

         and any dependent objects (e.g. InetAddress objects) are
         consistent.  An inconsistentValue error must be generated
         if an attempt to change an InetAddressType object would,
         for example, lead to an undefined InetAddress value.  In
         particular, InetAddressType/InetAddress pairs must be
         changed together if the address type changes (e.g. from
         ipv6(2) to ipv4(1))."
    SYNTAX      INTEGER {
                    unknown(0),
                    ipv4(1),
                    ipv6(2),
                    ipv4z(3),
                    ipv6z(4),
                    dns(16)
                }

InetAddress ::= TEXTUAL-CONVENTION

    STATUS      current
    DESCRIPTION
    
        "Denotes a generic Internet address.

An InetAddress value is always interpreted within the context of an InetAddressType value. Every usage of the InetAddress textual convention is required to specify the InetAddressType object which provides the context. It is suggested that the InetAddressType object is logically registered before the object(s) which use the InetAddress textual convention if they appear in the same logical row.

The value of an InetAddress object must always be consistent with the value of the associated InetAddressType object. Attempts to set an InetAddress object to a value which is inconsistent with the associated InetAddressType must fail with an inconsistentValue error.

         When this textual convention is used as the syntax of an
         index object, there may be issues with the limit of 128
         sub-identifiers specified in SMIv2, STD 58. In this case,
         the object definition MUST include a 'SIZE' clause to
         limit the number of potential instance sub-identifiers."
    SYNTAX      OCTET STRING (SIZE (0..255))

InetAddressIPv4 ::= TEXTUAL-CONVENTION

    DISPLAY-HINT "1d.1d.1d.1d"
    STATUS       current
    DESCRIPTION
        "Represents an IPv4 network address:
           octets   contents         encoding
            1-4     IPv4 address     network-byte order

The corresponding InetAddressType value is ipv4(1).

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or in
         conjunction with InetAddressType as a pair."
    SYNTAX       OCTET STRING (SIZE (4))

InetAddressIPv6 ::= TEXTUAL-CONVENTION

    DISPLAY-HINT "2x:2x:2x:2x:2x:2x:2x:2x"
    STATUS       current
    DESCRIPTION
    
        "Represents an IPv6 network address:
    
           octets   contents         encoding
            1-16    IPv6 address     network-byte order

The corresponding InetAddressType value is ipv6(2).

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or in
         conjunction with InetAddressType as a pair."
    SYNTAX       OCTET STRING (SIZE (16))

InetAddressIPv4z ::= TEXTUAL-CONVENTION

    DISPLAY-HINT "1d.1d.1d.1d%4d"
    STATUS       current
    DESCRIPTION
    
        "Represents a non-global IPv4 network address together
         with its zone index:

octets contents encoding

1-4 IPv4 address network-byte order

5-8 zone index network-byte order

The corresponding InetAddressType value is ipv4z(3).

The zone index (bytes 5-8) is used to disambiguate identical address values on nodes which have interfaces attached to different zones of the same scope. The zone index may contain the special value 0 which refers to the default zone for each scope.

This textual convention SHOULD NOT be used directly in object

         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or in
         conjunction with InetAddressType as a pair."
    SYNTAX OCTET STRING (SIZE (8))

InetAddressIPv6z ::= TEXTUAL-CONVENTION

    DISPLAY-HINT "2x:2x:2x:2x:2x:2x:2x:2x%4d"
    STATUS       current
    DESCRIPTION
        "Represents a non-global IPv6 network address together
         with its zone index:

octets contents encoding

1-16 IPv6 address network-byte order

17-20 zone index network-byte order

The corresponding InetAddressType value is ipv6z(4).

The zone index (bytes 17-20) is used to disambiguate identical address values on nodes which have interfaces attached to different zones of the same scope. The zone index may contain the special value 0 which refers to the default zone for each scope.

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or in
         conjunction with InetAddressType as a pair."
    SYNTAX OCTET STRING (SIZE (20))

InetAddressDNS ::= TEXTUAL-CONVENTION

    DISPLAY-HINT "255a"
    STATUS       current
    DESCRIPTION
        "Represents a DNS domain name. The name SHOULD be fully
         qualified whenever possible.

The corresponding InetAddressType is dns(16).

The DESCRIPTION clause of InetAddress objects that may have InetAddressDNS values must fully describe how (and when) such names are to be resolved to IP addresses.

         This textual convention SHOULD NOT be used directly in object
         definitions since it restricts addresses to a specific format.
         However, if it is used, it MAY be used either on its own or in
         conjunction with InetAddressType as a pair."
    SYNTAX       OCTET STRING (SIZE (1..255))

InetAddressPrefixLength ::= TEXTUAL-CONVENTION

    STATUS      current
    DESCRIPTION
        "Denotes the length of a generic Internet network address
         prefix. A value of n corresponds to an IP address mask
         which has n contiguous 1-bits from the most significant
         bit (MSB) and all other bits set to 0.

An InetAddressPrefixLength value is always interpreted within the context of an InetAddressType value. Every usage of the InetAddressPrefixLength textual convention is required to specify the InetAddressType object which provides the context. It is suggested that the InetAddressType object is logically registered before the object(s) which use the InetAddressPrefixLength textual convention if they appear in the same logical row.

InetAddressPrefixLength values that are larger than the maximum length of an IP address for a specific InetAddressType are treated as the maximum significant value applicable for the InetAddressType. The maximum significant value is 32 for the InetAddressType 'ipv4(1)' and 'ipv4z(3)' and 128 for the InetAddressType 'ipv6(2)' and 'ipv6z(4)'. The maximum significant value for the InetAddressType 'dns(16)' is 0.

         The value zero is object-specific and must be defined as
         part of the description of any object which uses this
         syntax. Examples of the usage of zero might include
         situations where the Internet network address prefix
         is unknown or does not apply."
    SYNTAX      Unsigned32

InetPortNumber ::= TEXTUAL-CONVENTION

    STATUS      current
    DESCRIPTION
        "Represents a 16 bit port number of an Internet transport
         layer protocol. Port numbers are assigned by IANA. A
         current list of all assignments is available from
         <http://www.iana.org/>.
    
         The value zero is object-specific and must be defined as
         part of the description of any object which uses this
         syntax. Examples of the usage of zero might include
         situations where a port number is unknown, or when the
         value zero is used as a wildcard in a filter."
    REFERENCE  "STD 6 (RFC 768), STD 7 (RFC 793) and RFC 2960"
    SYNTAX      Unsigned32 (0..65535)

InetAutonomousSystemNumber ::= TEXTUAL-CONVENTION

    STATUS      current
    DESCRIPTION
        "Represents an autonomous system number which identifies 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 ASs'. IANA maintains the AS number space and has
         delegated large parts to the regional registries.
    
         Autonomous system numbers are currently limited to 16 bits
         (0..65535). There is however work in progress to enlarge the
         autonomous system number space to 32 bits. This textual
         convention therefore uses an Unsigned32 value without a
         range restriction in order to support a larger autonomous
         system number space."
    REFERENCE  "RFC 1771, RFC 1930"
    SYNTAX      Unsigned32

END

4. Usage Hints

The InetAddressType and InetAddress textual conventions have been introduced to avoid over-constraining an object definition by the use of the IpAddress SMI base type which is IPv4 specific. An InetAddressType/InetAddress pair can represent IP addresses in various formats.

The InetAddressType and InetAddress objects SHOULD NOT be sub-typed in object definitions. Sub-typing binds the MIB module to specific address formats, which may cause serious problems if new address formats need to be introduced. Note that it is possible to write compliance statements in order to express that only a subset of the defined address types must be implemented to be compliant.

Every usage of the InetAddress or InetAddressPrefixLength textual conventions must specify which InetAddressType object provides the context for the interpretation of the InetAddress or InetAddressPrefixLength textual convention.

It is suggested that the InetAddressType object is logically registered before the object(s) which uses the InetAddress or InetAddressPrefixLength textual convention. An InetAddressType object is logically registered before an InetAddress or InetAddressPrefixLength object if it appears before the InetAddress or InetAddressPrefixLength object in the conceptual row (which includes any index objects). This rule allows programs such as MIB compilers to identify the InetAddressType of a given InetAddress or InetAddressPrefixLength object by searching for the InetAddressType object which precedes an InetAddress or InetAddressPrefixLength object.

4.1 Table Indexing

When a generic Internet address is used as an index, both the InetAddressType and InetAddress objects MUST be used. The InetAddressType object MUST be listed before the InetAddress object in the INDEX clause.

The IMPLIED keyword MUST NOT be used for an object of type InetAddress in an INDEX clause. Instance sub-identifiers are then of the form T.N.O1.O2...On, where T is the value of the InetAddressType object, O1...On are the octets in the InetAddress object, and N is the number of those octets.

There is a meaningful lexicographical ordering to tables indexed in this fashion. Command generator applications may lookup specific addresses of known type and value, issue GetNext requests for addresses of a single type, or issue GetNext requests for a specific type and address prefix.

4.2 Uniqueness of Addresses

IPv4 addresses were intended to be globally unique, current usage notwithstanding. IPv6 addresses were architected to have different scopes and hence uniqueness [19]. In particular, IPv6 "link-local" and "site-local" addresses are not guaranteed to be unique on any particular node. In such cases, the duplicate addresses must be configured on different interfaces. So the combination of an IPv6 address and a zone index is unique [21].

The InetAddressIPv6 textual convention has been defined to represent global IPv6 addresses and non-global IPv6 addresses in cases where no zone index is needed (e.g., on end hosts with a single interface). The InetAddressIPv6z textual convention has been defined to represent non-global IPv6 addresses in cases where a zone index is needed (e.g., a router connecting multiple zones). MIB designers who use InetAddressType/InetAddress pairs therefore do not need to define additional objects in order to support non-global addresses on nodes that connect multiple zones.

The InetAddressIPv4z is intended for use in MIBs (like the TCP-MIB) which report addresses in the address family used on the wire, but where the entity instrumented obtains such addresses from applications or administrators in a form which includes a zone index, such as v4-mapped IPv6 addresses.

The size of the zone index has been chosen so that it is consistent with (i) the numerical zone index defined in [21] and (ii) the sin6_scope_id field of the sockaddr_in6 structure defined in RFC 2553 [20].

4.3 Multiple Addresses per Host

A single host system may be configured with multiple addresses (IPv4 or IPv6), and possibly with multiple DNS names. Thus it is possible for a single host system to be accessible by multiple InetAddressType/InetAddress pairs.

If this could be an implementation or usage issue, the DESCRIPTION clause of the relevant objects must fully describe which address is reported in a given InetAddressType/InetAddress pair.

4.4 Resolving DNS Names

DNS names MUST be resolved to IP addresses when communication with the named host is required. This raises a temporal aspect to defining MIB objects whose value is a DNS name: When is the name translated to an address?

   For example, consider an object defined to indicate a forwarding
   destination, and whose value is a DNS name.  When does the forwarding
   entity resolve the DNS name?  Each time forwarding occurs or just
   once when the object was instantiated?

The DESCRIPTION clause of such objects SHOULD precisely define how and when any required name to address resolution is done.

Similarly, the DESCRIPTION clause of such objects SHOULD precisely define how and when a reverse lookup is being done if an agent has accessed instrumentation that knows about an IP address and the MIB module or implementation requires it to map the IP address to a DNS name.

5. Table Indexing Example

This example shows a table listing communication peers that are identified by either an IPv4 address, an IPv6 address or a DNS name. The table definition also prohibits entries with an empty address (whose type would be "unknown"). The size of a DNS name is limited to 64 characters in order to satisfy OID length constraints.

peerTable OBJECT-TYPE

       SYNTAX      SEQUENCE OF PeerEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A list of communication peers."
       ::= { somewhere 1 }

peerEntry OBJECT-TYPE

       SYNTAX      PeerEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry containing information about a particular peer."
       INDEX       { peerAddressType, peerAddress }
       ::= { peerTable 1 }
   
   PeerEntry ::= SEQUENCE {
       peerAddressType     InetAddressType,
       peerAddress         InetAddress,
       peerStatus          INTEGER
   }

peerAddressType OBJECT-TYPE

       SYNTAX      InetAddressType
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The type of Internet address by which the peer
            is reachable."
       ::= { peerEntry 1 }

peerAddress OBJECT-TYPE

       SYNTAX      InetAddress (SIZE (1..64))
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The Internet address for the peer. The type of this
            address is determined by the value of the peerAddressType
            object. Note that implementations must limit themselves
            to a single entry in this table per reachable peer.
            The peerAddress may not be empty due to the SIZE
            restriction.

If a row is created administratively by an SNMP operation and the address type value is dns(16), then the agent stores the DNS name internally. A DNS name lookup must be performed on the internally stored DNS name whenever it is being used to contact the peer.

            If a row is created by the managed entity itself and
            the address type value is dns(16), then the agent
            stores the IP address internally. A DNS reverse lookup
            must be performed on the internally stored IP address
            whenever the value is retrieved via SNMP."
       ::= { peerEntry 2 }

The following compliance statement specifies that compliant implementations need only support IPv4/IPv6 addresses without a zone indices. Support for DNS names or IPv4/IPv6 addresses with zone indices is not required.

peerCompliance MODULE-COMPLIANCE

       STATUS      current
       DESCRIPTION
           "The compliance statement of the peer MIB."
       
       MODULE      -- this module
       MANDATORY-GROUPS    { peerGroup }
       
       OBJECT  peerAddressType
       SYNTAX  InetAddressType { ipv4(1), ipv6(2) }
       DESCRIPTION
           "An implementation is only required to support IPv4
            and IPv6 addresses without zone indices."
       
       ::= { somewhere 2 }

Note that the SMIv2 does not permit inclusion of not-accessible objects in an object group (see section 3.1 in STD 58, RFC 2580 [8]). It is therefore not possible to formally refine the syntax of auxiliary objects which are not-accessible. In such a case, it is suggested to express the refinement informally in the DESCRIPTION clause of the MODULE-COMPLIANCE macro invocation.

6. Security Considerations

This module does not define any management objects. Instead, it defines a set of textual conventions which may be used by other MIB modules to define management objects.

Meaningful security considerations can only be written in the MIB modules that define management objects. This document has therefore no impact on the security of the Internet.

7. Acknowledgments

This document was produced by the Operations and Management Area "IPv6MIB" design team. The authors would like to thank Fred Baker, Randy Bush, Richard Draves, Mark Ellison, Bill Fenner, Jun-ichiro Hagino, Mike Heard, Tim Jenkins, Glenn Mansfield, Keith McCloghrie, Thomas Narten, Erik Nordmark, Peder Chr. Norgaard, Randy Presuhn, Andrew Smith, Dave Thaler, Kenneth White, Bert Wijnen, and Brian Zill for their comments and suggestions.

8. Intellectual Property Notice

The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP 11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat.

The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director.

9. Changes from RFC 2851

The following changes have been made relative to RFC 2851:

• Added new textual conventions InetAddressPrefixLength, InetPortNumber, and InetAutonomousSystemNumber.

• Rewrote the introduction to say clearly that in general, one should define MIB tables that work with all versions of IP. The other approach of multiple tables for different IP versions is strongly discouraged.

• Added text to the InetAddressType and InetAddress descriptions which requires that implementations must reject set operations with an inconsistentValue error if they lead to inconsistencies.

• Removed the strict ordering constraints. Description clauses now must explain which InetAddressType object provides the context for an InetAddress or InetAddressPrefixLength object.

• Aligned wordings with the IPv6 scoping architecture document.

• Split the InetAddressIPv6 textual convention into the two textual conventions (InetAddressIPv6 and InetAddressIPv6z) and introduced a new textual convention InetAddressIPv4z. Added ipv4z(3) and ipv6z(4) named numbers to the InetAddressType enumeration. Motivations for this change: (i) enable the introduction of a textual conventions for non-global IPv4 addresses, (ii) alignment with the textual conventions for transport addresses, (iii) simpler compliance statements in cases where support for IPv6 addresses with zone indices is not required, (iv) simplify implementations for host systems which will never have to report zone indices.

References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.
   
   [2]  Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for
        Describing SNMP Management Frameworks", RFC 2571, April 1999.
   
   [3]  Rose, M. and K. McCloghrie, "Structure and Identification of
        Management Information for TCP/IP-based Internets", STD 16, RFC
        1155, May 1990.
   
   [4]  Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16,
        RFC 1212, March 1991.
   
   [5]  Rose, M., "A Convention for Defining Traps for use with the
        SNMP", RFC 1215, March 1991.
   
   [6]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M. and S. Waldbusser, "Structure of Management Information
        Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
   
   [7]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58,
        RFC 2579, April 1999.
   
   [8]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M. and S. Waldbusser, "Conformance Statements for SMIv2", STD
        58, RFC 2580, April 1999.
   
   [9]  Case, J., Fedor, M., Schoffstall, M. and J. Davin, "A Simple
        Network Management Protocol (SNMP)", STD 15, RFC 1157, May 1990.
   
   [10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
        "Introduction to Community-based SNMPv2", RFC 1901, January
        1996.
   
   [11] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport
        Mappings for Version 2 of the Simple Network Management Protocol
        (SNMPv2)", RFC 1906, January 1996.
   
   [12] Case, J., Harrington, D., Presuhn, R. and B. Wijnen, "Message
        Processing and Dispatching for the Simple Network Management
        Protocol (SNMP)", RFC 2572, April 1999.
   
   [13] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM)
        for version 3 of the Simple Network Management Protocol
        (SNMPv3)", RFC 2574, April 1999.
   
   [14] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol
        Operations for Version 2 of the Simple Network Management
        Protocol (SNMPv2)", RFC 1905, January 1996.
   
   [15] Levi, D., Meyer, P. and B. Stewart, "SNMP Applications", RFC
        2573, April 1999.
   
   [16] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access
        Control Model (VACM) for the Simple Network Management Protocol
        (SNMP)", RFC 2575, April 1999.
   
   [17] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction
        to Version 3 of the Internet-standard Network Management
        Framework", RFC 2570, April 1999.
   
   [18] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB",
        RFC 2863, June 2000.
   
   [19] Hinden, R. and S. Deering, "IP Version 6 Addressing
        Architecture", RFC 2373, July 1998.
   
   [20] Gilligan, R., Thomson, S., Bound, J. and W. Stevens, "Basic
        Socket Interface Extensions for IPv6", RFC 2553, March 1999.

[21] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., Onoe, A.

and B. Zill, "IPv6 Scoped Address Architecture", Work in Progress.

Authors' Addresses

   Mike Daniele
   Consultant
   19 Pinewood Rd
   Hudson, NH  03051
   USA
   
   Phone: +1 603 883-6365
   EMail: md@world.std.com
   
   Brian Haberman
   
   Phone: +1 919 949-4828
   EMail: bkhabs@nc.rr.com

Shawn A. Routhier
Wind River Systems, Inc.
500 Wind River Way
Alameda, CA 94501
USA

   Phone: +1 510 749 2095
   EMail: sar@epilogue.com

Juergen Schoenwaelder
TU Braunschweig
Bueltenweg 74/75
38106 Braunschweig
Germany

   Phone: +49 531 391-3289
   EMail: schoenw@ibr.cs.tu-bs.de

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