RFC6434

From RFC-Wiki

Internet Engineering Task Force (IETF) E. Jankiewicz Request for Comments: 6434 SRI International, Inc. Obsoletes: 4294 J. Loughney Category: Informational Nokia ISSN: 2070-1721 T. Narten 

                                                     IBM Corporation
                                                       December 2011

                     IPv6 Node Requirements

Abstract

This document defines requirements for IPv6 nodes. It is expected that IPv6 will be deployed in a wide range of devices and situations. Specifying the requirements for IPv6 nodes allows IPv6 to function well and interoperate in a large number of situations and deployments.

This document obsoletes RFC 4294.

Status of This Memo

This document is not an Internet Standards Track specification; it is published for informational purposes.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6434.

Copyright Notice

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must

include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 

 5.3.  Default Router Preferences and More-Specific Routes -

 5.8.  ICMP for the Internet Protocol Version 6 (IPv6) - RFC

   5.9.1.  IP Version 6 Addressing Architecture - RFC 4291  . . . 11
   5.9.2.  IPv6 Stateless Address Autoconfiguration - RFC 4862  . 11
   5.9.3.  Privacy Extensions for Address Configuration in

   5.9.5.  Stateful Address Autoconfiguration (DHCPv6) - RFC

6. DHCP versus Router Advertisement Options for Host 

 7.2.  Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

   7.2.2.  Use of Router Advertisements in Managed

 7.3.  IPv6 Router Advertisement Options for DNS

   8.1.1.  Basic Transition Mechanisms for IPv6 Hosts and

 9.1.  Textual Representation of IPv6 Addresses - RFC 5952  . . . 16

 12.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315 . . 19

   13.1.2. Management Information Base for the Internet

Introduction

This document defines common functionality required from both IPv6 hosts and routers. Many IPv6 nodes will implement optional or additional features, but this document collects and summarizes requirements from other published Standards Track documents in one place.

This document tries to avoid discussion of protocol details and references RFCs for this purpose. This document is intended to be an applicability statement and to provide guidance as to which IPv6 specifications should be implemented in the general case and which specifications may be of interest to specific deployment scenarios. This document does not update any individual protocol document RFCs.

Although this document points to different specifications, it should be noted that in many cases, the granularity of a particular requirement will be smaller than a single specification, as many specifications define multiple, independent pieces, some of which may not be mandatory. In addition, most specifications define both client and server behavior in the same specification, while many implementations will be focused on only one of those roles.

This document defines a minimal level of requirement needed for a device to provide useful internet service and considers a broad range of device types and deployment scenarios. Because of the wide range of deployment scenarios, the minimal requirements specified in this document may not be sufficient for all deployment scenarios. It is perfectly reasonable (and indeed expected) for other profiles to define additional or stricter requirements appropriate for specific usage and deployment environments. For example, this document does not mandate that all clients support DHCP, but some deployment scenarios may deem it appropriate to make such a requirement. For example, government agencies in the USA have defined profiles for specialized requirements for IPv6 in target environments (see [DODv6] and [USGv6]).

As it is not always possible for an implementer to know the exact usage of IPv6 in a node, an overriding requirement for IPv6 nodes is that they should adhere to Jon Postel's Robustness Principle: "Be conservative in what you do, be liberal in what you accept from others" RFC0793.

Scope of This Document

IPv6 covers many specifications. It is intended that IPv6 will be deployed in many different situations and environments. Therefore, it is important to develop requirements for IPv6 nodes to ensure interoperability.

This document assumes that all IPv6 nodes meet the minimum requirements specified here.

Description of IPv6 Nodes

From the Internet Protocol, Version 6 (IPv6) Specification RFC2460, we have the following definitions:

IPv6 node - a device that implements IPv6.

IPv6 router - a node that forwards IPv6 packets not explicitly 

             addressed to itself.

IPv6 host - any node that is not a router.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 RFC2119.

Abbreviations Used in This Document

ATM Asynchronous Transfer Mode

AH Authentication Header

DAD Duplicate Address Detection

ESP Encapsulating Security Payload

ICMP Internet Control Message Protocol

IKE Internet Key Exchange

MIB Management Information Base

MLD Multicast Listener Discovery

MTU Maximum Transmission Unit

NA Neighbor Advertisement

NBMA Non-Broadcast Multiple Access

ND Neighbor Discovery

NS Neighbor Solicitation

NUD Neighbor Unreachability Detection

PPP Point-to-Point Protocol

Sub-IP Layer

An IPv6 node must include support for one or more IPv6 link-layer specifications. Which link-layer specifications an implementation should include will depend upon what link-layers are supported by the hardware available on the system. It is possible for a conformant IPv6 node to support IPv6 on some of its interfaces and not on others.

As IPv6 is run over new layer 2 technologies, it is expected that new specifications will be issued. In the following, we list some of the layer 2 technologies for which an IPv6 specification has been developed. It is provided for informational purposes only and may not be complete.

- Transmission of IPv6 Packets over Ethernet Networks RFC2464

- IPv6 over ATM Networks RFC2492

- Transmission of IPv6 Packets over Frame Relay Networks 

  Specification RFC2590

- Transmission of IPv6 Packets over IEEE 1394 Networks RFC3146

- Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) 

  Packets over Fibre Channel RFC4338

- Transmission of IPv6 Packets over IEEE 802.15.4 Networks RFC4944

- Transmission of IPv6 via the IPv6 Convergence Sublayer over IEEE 

  802.16 Networks RFC5121

- IP version 6 over PPP RFC5072

In addition to traditional physical link-layers, it is also possible to tunnel IPv6 over other protocols. Examples include:

- Teredo: Tunneling IPv6 over UDP through Network Address 

  Translations (NATs) RFC4380

- Section 3 of "Basic Transition Mechanisms for IPv6 Hosts and 

  Routers" RFC4213

IP Layer

Internet Protocol Version 6 - RFC 2460

The Internet Protocol Version 6 is specified in RFC2460. This specification MUST be supported.

Any unrecognized extension headers or options MUST be processed as described in RFC 2460.

The node MUST follow the packet transmission rules in RFC 2460.

Nodes MUST always be able to send, receive, and process fragment headers. All conformant IPv6 implementations MUST be capable of sending and receiving IPv6 packets; the forwarding functionality MAY be supported. Overlapping fragments MUST be handled as described in RFC5722.

RFC 2460 specifies extension headers and the processing for these headers.

An IPv6 node MUST be able to process these headers. An exception is Routing Header type 0 (RH0), which was deprecated by RFC5095 due to security concerns and which MUST be treated as an unrecognized routing type.

All nodes SHOULD support the setting and use of the IPv6 Flow Label field as defined in the IPv6 Flow Label specification RFC6437. Forwarding nodes such as routers and load distributors MUST NOT depend only on Flow Label values being uniformly distributed. It is RECOMMENDED that source hosts support the flow label by setting the Flow Label field for all packets of a given flow to the same value chosen from an approximation to a discrete uniform distribution.

Neighbor Discovery for IPv6 - RFC 4861

Neighbor Discovery is defined in RFC4861; the definition was updated by RFC5942. Neighbor Discovery SHOULD be supported. RFC 4861 states: 

  Unless specified otherwise (in a document that covers operating IP
  over a particular link type) this document applies to all link
  types.  However, because ND uses link-layer multicast for some of
  its services, it is possible that on some link types (e.g., Non-
  Broadcast Multi-Access (NBMA) links), alternative protocols or
  mechanisms to implement those services will be specified (in the
  appropriate document covering the operation of IP over a
  particular link type).  The services described in this document
  that are not directly dependent on multicast, such as Redirects,
  next-hop determination, Neighbor Unreachability Detection, etc.,
  are expected to be provided as specified in this document.  The
  details of how one uses ND on NBMA links are addressed in
  RFC2491.

Some detailed analysis of Neighbor Discovery follows:

Router Discovery is how hosts locate routers that reside on an attached link. Hosts MUST support Router Discovery functionality.

Prefix Discovery is how hosts discover the set of address prefixes that define which destinations are on-link for an attached link. Hosts MUST support Prefix Discovery.

Hosts MUST also implement Neighbor Unreachability Detection (NUD) for all paths between hosts and neighboring nodes. NUD is not required for paths between routers. However, all nodes MUST respond to unicast Neighbor Solicitation (NS) messages.

Hosts MUST support the sending of Router Solicitations and the receiving of Router Advertisements. The ability to understand individual Router Advertisement options is dependent on supporting the functionality making use of the particular option.

All nodes MUST support the sending and receiving of Neighbor Solicitation (NS) and Neighbor Advertisement (NA) messages. NS and NA messages are required for Duplicate Address Detection (DAD).

Hosts SHOULD support the processing of Redirect functionality. Routers MUST support the sending of Redirects, though not necessarily for every individual packet (e.g., due to rate limiting). Redirects are only useful on networks supporting hosts. In core networks dominated by routers, Redirects are typically disabled. The sending

of Redirects SHOULD be disabled by default on backbone routers. They MAY be enabled by default on routers intended to support hosts on edge networks.

"IPv6 Host-to-Router Load Sharing" RFC4311 includes additional recommendations on how to select from a set of available routers. RFC4311 SHOULD be supported.

Default Router Preferences and More-Specific Routes - RFC 4191

"Default Router Preferences and More-Specific Routes" RFC4191 provides support for nodes attached to multiple (different) networks, each providing routers that advertise themselves as default routers via Router Advertisements. In some scenarios, one router may provide connectivity to destinations the other router does not, and choosing the "wrong" default router can result in reachability failures. In such cases, RFC 4191 can help.

Small Office/Home Office (SOHO) deployments supported by routers adhering to RFC6204 use RFC 4191 to advertise routes to certain local destinations. Consequently, nodes that will be deployed in SOHO environments SHOULD implement RFC 4191.

SEcure Neighbor Discovery (SEND) - RFC 3971

SEND RFC3971 and Cryptographically Generated Address (CGA) RFC3972 provide a way to secure the message exchanges of Neighbor Discovery. SEND is a new technology in that it has no IPv4 counterpart, but it has significant potential to address certain classes of spoofing attacks. While there have been some implementations of SEND, there has been only limited deployment experience to date in using the technology. In addition, the IETF working group Cga & Send maIntenance (csi) is currently working on additional extensions intended to make SEND more attractive for deployment.

At this time, SEND is considered optional, and IPv6 nodes MAY provide SEND functionality.

IPv6 Router Advertisement Flags Option - RFC 5175

Router Advertisements include an 8-bit field of single-bit Router Advertisement flags. The Router Advertisement Flags Option extends the number of available flag bits by 48 bits. At the time of this writing, 6 of the original 8 single-bit flags have been assigned, while 2 remain available for future assignment. No flags have been defined that make use of the new option, and thus, strictly speaking, there is no requirement to implement the option today. However,

implementations that are able to pass unrecognized options to a higher-level entity that may be able to understand them (e.g., a user-level process using a "raw socket" facility) MAY take steps to handle the option in anticipation of a future usage.

Path MTU Discovery and Packet Size

Path MTU Discovery - RFC 1981

"Path MTU Discovery for IP version 6" RFC1981 SHOULD be supported. From RFC2460: 

  It is strongly recommended that IPv6 nodes implement Path MTU
  Discovery RFC1981, in order to discover and take advantage of
  path MTUs greater than 1280 octets.  However, a minimal IPv6
  implementation (e.g., in a boot ROM) may simply restrict itself to
  sending packets no larger than 1280 octets, and omit
  implementation of Path MTU Discovery.

The rules in RFC2460 and RFC5722 MUST be followed for packet fragmentation and reassembly.

One operational issue with Path MTU Discovery occurs when firewalls block ICMP Packet Too Big messages. Path MTU Discovery relies on such messages to determine what size messages can be successfully sent. "Packetization Layer Path MTU Discovery" RFC4821 avoids having a dependency on Packet Too Big messages.

IPv6 Jumbograms - RFC 2675

IPv6 Jumbograms RFC2675 are an optional extension that allow the sending of IP datagrams larger than 65.535 bytes. IPv6 Jumbograms make use of IPv6 hop-by-hop options and are only suitable on paths in which every hop and link are capable of supporting Jumbograms (e.g., within a campus or datacenter). To date, few implementations exist, and there is essentially no reported experience from usage.

Consequently, IPv6 Jumbograms RFC2675 remain optional at this time.

ICMP for the Internet Protocol Version 6 (IPv6) - RFC 4443

ICMPv6 RFC4443 MUST be supported. "Extended ICMP to Support Multi- Part Messages" RFC4884 MAY be supported.

Addressing

IP Version 6 Addressing Architecture - RFC 4291

The IPv6 Addressing Architecture RFC4291 MUST be supported.

IPv6 Stateless Address Autoconfiguration - RFC 4862

Hosts MUST support IPv6 Stateless Address Autoconfiguration as defined in RFC4862. Configuration of static address(es) may be supported as well.

Nodes that are routers MUST be able to generate link-local addresses as described in RFC4862.

From RFC 4862: 

  The autoconfiguration process specified in this document applies
  only to hosts and not routers.  Since host autoconfiguration uses
  information advertised by routers, routers will need to be
  configured by some other means.  However, it is expected that
  routers will generate link-local addresses using the mechanism
  described in this document.  In addition, routers are expected to
  successfully pass the Duplicate Address Detection procedure
  described in this document on all addresses prior to assigning
  them to an interface.

All nodes MUST implement Duplicate Address Detection. Quoting from Section 5.4 of RFC 4862: 

  Duplicate Address Detection MUST be performed on all unicast
  addresses prior to assigning them to an interface, regardless of
  whether they are obtained through stateless autoconfiguration,
  DHCPv6, or manual configuration, with the following [exceptions
  noted therein].

"Optimistic Duplicate Address Detection (DAD) for IPv6" RFC4429 specifies a mechanism to reduce delays associated with generating addresses via Stateless Address Autoconfiguration RFC4862. RFC 4429 was developed in conjunction with Mobile IPv6 in order to reduce the time needed to acquire and configure addresses as devices quickly move from one network to another, and it is desirable to minimize transition delays. For general purpose devices, RFC 4429 remains optional at this time.

Privacy Extensions for Address Configuration in IPv6 - RFC 4941

Privacy Extensions for Stateless Address Autoconfiguration RFC4941 addresses a specific problem involving a client device whose user is concerned about its activity or location being tracked. The problem arises both for a static client and for one that regularly changes its point of attachment to the Internet. When using Stateless Address Autoconfiguration RFC4862, the Interface Identifier portion of formed addresses stays constant and is globally unique. Thus, although a node's global IPv6 address will change if it changes its point of attachment, the Interface Identifier portion of those addresses remains the same, making it possible for servers to track the location of an individual device as it moves around or its pattern of activity if it remains in one place. This may raise privacy concerns as described in RFC4862.

In such situations, RFC 4941 SHOULD be implemented. In other cases, such as with dedicated servers in a data center, RFC 4941 provides limited or no benefit.

Implementers of RFC 4941 should be aware that certain addresses are reserved and should not be chosen for use as temporary addresses. Consult "Reserved IPv6 Interface Identifiers" RFC5453 for more details.

Default Address Selection for IPv6 - RFC 3484

The rules specified in the Default Address Selection for IPv6 RFC3484 document MUST be implemented. IPv6 nodes will need to deal with multiple addresses configured simultaneously.

Stateful Address Autoconfiguration (DHCPv6) - RFC 3315

DHCPv6 RFC3315 can be used to obtain and configure addresses. In general, a network may provide for the configuration of addresses through Router Advertisements, DHCPv6, or both. There will be a wide range of IPv6 deployment models and differences in address assignment requirements, some of which may require DHCPv6 for address assignment. Consequently, all hosts SHOULD implement address configuration via DHCPv6.

In the absence of a router, IPv6 nodes using DHCP for address assignment MAY initiate DHCP to obtain IPv6 addresses and other configuration information, as described in Section 5.5.2 of RFC4862.

5.10. Multicast Listener Discovery (MLD) for IPv6

Nodes that need to join multicast groups MUST support MLDv1 RFC2710. MLDv1 is needed by any node that is expected to receive and process multicast traffic. Note that Neighbor Discovery (as used on most link types -- see Section 5.2) depends on multicast and requires that nodes join Solicited Node multicast addresses.

MLDv2 RFC3810 extends the functionality of MLDv1 by supporting Source-Specific Multicast. The original MLDv2 protocol RFC3810 supporting Source-Specific Multicast RFC4607 supports two types of "filter modes". Using an INCLUDE filter, a node indicates a multicast group along with a list of senders for the group from which it wishes to receive traffic. Using an EXCLUDE filter, a node indicates a multicast group along with a list of senders from which it wishes to exclude receiving traffic. In practice, operations to block source(s) using EXCLUDE mode are rarely used but add considerable implementation complexity to MLDv2. Lightweight MLDv2 RFC5790 is a simplified subset of the original MLDv2 specification that omits EXCLUDE filter mode to specify undesired source(s).

Nodes SHOULD implement either MLDv2 RFC3810 or Lightweight MLDv2 RFC5790. Specifically, nodes supporting applications using Source- Specific Multicast that expect to take advantage of MLDv2's EXCLUDE functionality RFC3810 MUST support MLDv2 as defined in RFC3810, RFC4604, and RFC4607. Nodes supporting applications that expect to only take advantage of MLDv2's INCLUDE functionality as well as Any-Source Multicast will find it sufficient to support MLDv2 as defined in RFC5790.

If a node only supports applications that use Any-Source Multicast (i.e, they do not use Source-Specific Multicast), implementing MLDv1 RFC2710 is sufficient. In all cases, however, nodes are strongly encouraged to implement MLDv2 or Lightweight MLDv2 rather than MLDv1, as the presence of a single MLDv1 participant on a link requires that all other nodes on the link operate in version 1 compatibility mode.

When MLDv1 is used, the rules in the Source Address Selection for the Multicast Listener Discovery (MLD) Protocol RFC3590 MUST be followed.

DHCP versus Router Advertisement Options for Host Configuration

In IPv6, there are two main protocol mechanisms for propagating configuration information to hosts: Router Advertisements (RAs) and DHCP. Historically, RA options have been restricted to those deemed essential for basic network functioning and for which all nodes are configured with exactly the same information. Examples include the

Prefix Information Options, the MTU option, etc. On the other hand, DHCP has generally been preferred for configuration of more general parameters and for parameters that may be client-specific. That said, identifying the exact line on whether a particular option should be configured via DHCP versus an RA option has not always been easy. Generally speaking, however, there has been a desire to define only one mechanism for configuring a given option, rather than defining multiple (different) ways of configuring the same information.

One issue with having multiple ways of configuring the same information is that interoperability suffers if a host chooses one mechanism but the network operator chooses a different mechanism. For "closed" environments, where the network operator has significant influence over what devices connect to the network and thus what configuration mechanisms they support, the operator may be able to ensure that a particular mechanism is supported by all connected hosts. In more open environments, however, where arbitrary devices may connect (e.g., a WIFI hotspot), problems can arise. To maximize interoperability in such environments, hosts would need to implement multiple configuration mechanisms to ensure interoperability.

Originally, in IPv6, configuring information about DNS servers was performed exclusively via DHCP. In 2007, an RA option was defined but was published as Experimental RFC5006. In 2010, "IPv6 Router Advertisement Options for DNS Configuration" RFC6106 was published as a Standards Track document. Consequently, DNS configuration information can now be learned either through DHCP or through RAs. Hosts will need to decide which mechanism (or whether both) should be implemented. Specific guidance regarding DNS server discovery is discussed in Section 7.

DNS and DHCP

DNS

DNS is described in RFC1034, RFC1035, RFC3363, and RFC3596. Not all nodes will need to resolve names; those that will never need to resolve DNS names do not need to implement resolver functionality. However, the ability to resolve names is a basic infrastructure capability on which applications rely, and most nodes will need to provide support. All nodes SHOULD implement stub-resolver RFC1034 functionality, as in RFC1034, Section 5.3.1, with support for:

- AAAA type Resource Records RFC3596;

- reverse addressing in ip6.arpa using PTR records RFC3596;

- Extension Mechanisms for DNS (EDNS0) RFC2671 to allow for DNS 

  packet sizes larger than 512 octets.

Those nodes are RECOMMENDED to support DNS security extensions RFC4033 RFC4034 RFC4035.

Those nodes are NOT RECOMMENDED to support the experimental A6 Resource Records RFC3363.

Dynamic Host Configuration Protocol for IPv6 (DHCPv6) - RFC 3315

Other Configuration Information

IPv6 nodes use DHCP RFC3315 to obtain address configuration information (see Section 5.9.5) and to obtain additional (non- address) configuration. If a host implementation supports applications or other protocols that require configuration that is only available via DHCP, hosts SHOULD implement DHCP. For specialized devices on which no such configuration need is present, DHCP may not be necessary.

An IPv6 node can use the subset of DHCP (described in RFC3736) to obtain other configuration information.

Use of Router Advertisements in Managed Environments

Nodes using the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) are expected to determine their default router information and on- link prefix information from received Router Advertisements.

IPv6 Router Advertisement Options for DNS Configuration - RFC 6106

Router Advertisements have historically limited options to those that are critical to basic IPv6 functioning. Originally, DNS configuration was not included as an RA option, and DHCP was the recommended way to obtain DNS configuration information. Over time, the thinking surrounding such an option has evolved. It is now generally recognized that few nodes can function adequately without having access to a working DNS resolver. RFC5006 was published as an Experimental document in 2007, and recently, a revised version was placed on the Standards Track RFC6106.

Implementations SHOULD implement the DNS RA option RFC6106.

IPv4 Support and Transition

IPv6 nodes MAY support IPv4.

Transition Mechanisms

Basic Transition Mechanisms for IPv6 Hosts and Routers - RFC

    4213

If an IPv6 node implements dual stack and tunneling, then RFC4213 MUST be supported.

Application Support

Textual Representation of IPv6 Addresses - RFC 5952

Software that allows users and operators to input IPv6 addresses in text form SHOULD support "A Recommendation for IPv6 Address Text Representation" RFC5952.

Application Programming Interfaces (APIs)

There are a number of IPv6-related APIs. This document does not mandate the use of any, because the choice of API does not directly relate to on-the-wire behavior of protocols. Implementers, however, would be advised to consider providing a common API or reviewing existing APIs for the type of functionality they provide to applications.

"Basic Socket Interface Extensions for IPv6" RFC3493 provides IPv6 functionality used by typical applications. Implementers should note that RFC3493 has been picked up and further standardized by the Portable Operating System Interface (POSIX) [POSIX].

"Advanced Sockets Application Program Interface (API) for IPv6" RFC3542 provides access to advanced IPv6 features needed by diagnostic and other more specialized applications.

"IPv6 Socket API for Source Address Selection" RFC5014 provides facilities that allow an application to override the default Source Address Selection rules of RFC3484.

"Socket Interface Extensions for Multicast Source Filters" RFC3678 provides support for expressing source filters on multicast group memberships.

"Extension to Sockets API for Mobile IPv6" RFC4584 provides application support for accessing and enabling Mobile IPv6 RFC6275 features.

10. Mobility

Mobile IPv6 RFC6275 and associated specifications RFC3776 RFC4877 allow a node to change its point of attachment within the Internet, while maintaining (and using) a permanent address. All communication using the permanent address continues to proceed as expected even as the node moves around. The definition of Mobile IP includes requirements for the following types of nodes: 

  - mobile nodes

  - correspondent nodes with support for route optimization

  - home agents

  - all IPv6 routers

At the present time, Mobile IP has seen only limited implementation and no significant deployment, partly because it originally assumed an IPv6-only environment rather than a mixed IPv4/IPv6 Internet. Recently, additional work has been done to support mobility in mixed- mode IPv4 and IPv6 networks RFC5555.

More usage and deployment experience is needed with mobility before any specific approach can be recommended for broad implementation in all hosts and routers. Consequently, RFC6275, RFC5555, and associated standards such as RFC4877 are considered a MAY at this time.

11. Security

This section describes the specification for security for IPv6 nodes.

Achieving security in practice is a complex undertaking. Operational procedures, protocols, key distribution mechanisms, certificate management approaches, etc., are all components that impact the level of security actually achieved in practice. More importantly, deficiencies or a poor fit in any one individual component can significantly reduce the overall effectiveness of a particular security approach.

IPsec provides channel security at the Internet layer, making it possible to provide secure communication for all (or a subset of) communication flows at the IP layer between pairs of internet nodes. IPsec provides sufficient flexibility and granularity that individual TCP connections can (selectively) be protected, etc.

Although IPsec can be used with manual keying in some cases, such usage has limited applicability and is not recommended.

A range of security technologies and approaches proliferate today (e.g., IPsec, Transport Layer Security (TLS), Secure SHell (SSH), etc.) No one approach has emerged as an ideal technology for all needs and environments. Moreover, IPsec is not viewed as the ideal security technology in all cases and is unlikely to displace the others.

Previously, IPv6 mandated implementation of IPsec and recommended the key management approach of IKE. This document updates that recommendation by making support of the IPsec Architecture RFC4301 a SHOULD for all IPv6 nodes. Note that the IPsec Architecture requires (e.g., Section 4.5 of RFC 4301) the implementation of both manual and automatic key management. Currently, the default automated key management protocol to implement is IKEv2 RFC5996.

This document recognizes that there exists a range of device types and environments where approaches to security other than IPsec can be justified. For example, special-purpose devices may support only a very limited number or type of applications, and an application- specific security approach may be sufficient for limited management or configuration capabilities. Alternatively, some devices may run on extremely constrained hardware (e.g., sensors) where the full IPsec Architecture is not justified.

11.1. Requirements

"Security Architecture for the Internet Protocol" RFC4301 SHOULD be supported by all IPv6 nodes. Note that the IPsec Architecture requires (e.g., Section 4.5 of RFC4301) the implementation of both manual and automatic key management. Currently, the default automated key management protocol to implement is IKEv2. As required in RFC4301, IPv6 nodes implementing the IPsec Architecture MUST implement ESP RFC4303 and MAY implement AH RFC4302.

11.2. Transforms and Algorithms

The current set of mandatory-to-implement algorithms for the IPsec Architecture are defined in "Cryptographic Algorithm Implementation Requirements For ESP and AH" RFC4835. IPv6 nodes implementing the IPsec Architecture MUST conform to the requirements in RFC4835. Preferred cryptographic algorithms often change more frequently than security protocols. Therefore, implementations MUST allow for migration to new algorithms, as RFC 4835 is replaced or updated in the future.

The current set of mandatory-to-implement algorithms for IKEv2 are defined in "Cryptographic Algorithms for Use in the Internet Key Exchange Version 2 (IKEv2)" RFC4307. IPv6 nodes implementing IKEv2 MUST conform to the requirements in RFC4307 and/or any future updates or replacements to RFC4307.

12. Router-Specific Functionality

This section defines general host considerations for IPv6 nodes that act as routers. Currently, this section does not discuss routing- specific requirements.

12.1. IPv6 Router Alert Option - RFC 2711

The IPv6 Router Alert Option RFC2711 is an optional IPv6 Hop-by-Hop Header that is used in conjunction with some protocols (e.g., RSVP RFC2205 or Multicast Listener Discovery (MLD) RFC2710). The Router Alert option will need to be implemented whenever protocols that mandate its usage (e.g., MLD) are implemented. See Section 5.10.

12.2. Neighbor Discovery for IPv6 - RFC 4861

Sending Router Advertisements and processing Router Solicitations MUST be supported.

Section 7 of RFC6275 includes some mobility-specific extensions to Neighbor Discovery. Routers SHOULD implement Sections 7.3 and 7.5, even if they do not implement Home Agent functionality.

12.3. Stateful Address Autoconfiguration (DHCPv6) - RFC 3315

A single DHCP server (RFC3315 or RFC4862) can provide configuration information to devices directly attached to a shared link, as well as to devices located elsewhere within a site. Communication between a client and a DHCP server located on different links requires the use of DHCP relay agents on routers.

In simple deployments, consisting of a single router and either a single LAN or multiple LANs attached to the single router, together with a WAN connection, a DHCP server embedded within the router is one common deployment scenario (e.g., RFC6204). However, there is no need for relay agents in such scenarios.

In more complex deployment scenarios, such as within enterprise or service provider networks, the use of DHCP requires some level of configuration, in order to configure relay agents, DHCP servers, etc. In such environments, the DHCP server might even be run on a traditional server, rather than as part of a router.

Because of the wide range of deployment scenarios, support for DHCP server functionality on routers is optional. However, routers targeted for deployment within more complex scenarios (as described above) SHOULD support relay agent functionality. Note that "Basic Requirements for IPv6 Customer Edge Routers" RFC6204 requires implementation of a DHCPv6 server function in IPv6 Customer Edge (CE) routers.

13. Network Management

Network management MAY be supported by IPv6 nodes. However, for IPv6 nodes that are embedded devices, network management may be the only possible way of controlling these nodes.

13.1. Management Information Base (MIB) Modules

The following two MIB modules SHOULD be supported by nodes that support a Simple Network Management Protocol (SNMP) agent.

13.1.1. IP Forwarding Table MIB

The IP Forwarding Table MIB RFC4292 SHOULD be supported by nodes that support an SNMP agent.

13.1.2. Management Information Base for the Internet Protocol (IP)

The IP MIB RFC4293 SHOULD be supported by nodes that support an SNMP agent.

14. Security Considerations

This document does not directly affect the security of the Internet, beyond the security considerations associated with the individual protocols.

Security is also discussed in Section 11 above.

15. Authors and Acknowledgments

15.1. Authors and Acknowledgments (Current Document)

For this version of the IPv6 Node Requirements document, the authors would like to thank Hitoshi Asaeda, Brian Carpenter, Tim Chown, Ralph Droms, Sheila Frankel, Sam Hartman, Bob Hinden, Paul Hoffman, Pekka Savola, Yaron Sheffer, and Dave Thaler for their comments.

15.2. Authors and Acknowledgments from RFC 4279

The original version of this document (RFC 4279) was written by the IPv6 Node Requirements design team: 

  Jari Arkko
  [email protected]

  Marc Blanchet
  [email protected]

  Samita Chakrabarti
  [email protected]

  Alain Durand
  [email protected]

  Gerard Gastaud
  [email protected]

  Jun-ichiro Itojun Hagino
  [email protected]

  Atsushi Inoue
  [email protected]

  Masahiro Ishiyama
  [email protected]

  John Loughney
  [email protected]

  Rajiv Raghunarayan
  [email protected]

  Shoichi Sakane
  [email protected]

  Dave Thaler
  [email protected]

  Juha Wiljakka
  [email protected]

The authors would like to thank Ran Atkinson, Jim Bound, Brian Carpenter, Ralph Droms, Christian Huitema, Adam Machalek, Thomas Narten, Juha Ollila, and Pekka Savola for their comments. Thanks to Mark Andrews for comments and corrections on DNS text. Thanks to Alfred Hoenes for tracking the updates to various RFCs.

16. Appendix: Changes from RFC 4294

There have been many editorial clarifications as well as significant additions and updates. While this section highlights some of the changes, readers should not rely on this section for a comprehensive list of all changes.

1. Updated the Introduction to indicate that this document is an 

    applicability statement and is aimed at general nodes.

2. Significantly updated the section on Mobility protocols, adding 

    references and downgrading previous SHOULDs to MAYs.

3. Changed Sub-IP Layer section to just list relevant RFCs, and 

    added some more RFCs.

4. Added section on SEND (it is a MAY).

5. Revised section on Privacy Extensions RFC4941 to add more 

    nuance to recommendation.

6. Completely revised IPsec/IKEv2 section, downgrading overall 

    recommendation to a SHOULD.

7. Upgraded recommendation of DHCPv6 to SHOULD.

8. Added background section on DHCP versus RA options, added SHOULD 

    recommendation for DNS configuration via RAs RFC6106, and
    cleaned up DHCP recommendations.

9. Added recommendation that routers implement Sections 7.3 and 7.5 

    of RFC6275.

10. Added pointer to subnet clarification document RFC5942.

11. Added text that "IPv6 Host-to-Router Load Sharing" RFC4311 

    SHOULD be implemented.

12. Added reference to RFC5722 (Overlapping Fragments), and made 

    it a MUST to implement.

13. Made "A Recommendation for IPv6 Address Text Representation" 

    RFC5952 a SHOULD.

14. Removed mention of "DNAME" from the discussion about RFC3363.

15. Numerous updates to reflect newer versions of IPv6 documents, 

    including RFC4443, RFC4291, RFC3596, and RFC4213.

16. Removed discussion of "Managed" and "Other" flags in RAs. There 

    is no consensus at present on how to process these flags, and
    discussion of their semantics was removed in the most recent
    update of Stateless Address Autoconfiguration RFC4862.

17. Added many more references to optional IPv6 documents.

18. Made "A Recommendation for IPv6 Address Text Representation" 

    RFC5952 a SHOULD.

19. Added reference to RFC5722 (Overlapping Fragments), and made 

    it a MUST to implement.

20. Updated MLD section to include reference to Lightweight MLD 

    RFC5790.

21. Added SHOULD recommendation for "Default Router Preferences and 

    More-Specific Routes" RFC4191.

22. Made "IPv6 Flow Label Specification" RFC6437 a SHOULD.

17. References

17.1. Normative References

RFC1034 Mockapetris, P., "Domain names - concepts and facilities", 

          STD 13, RFC 1034, November 1987.

RFC1035 Mockapetris, P., "Domain names - implementation and 

          specification", STD 13, RFC 1035, November 1987.

RFC1981 McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery 

          for IP version 6", RFC 1981, August 1996.

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate 

          Requirement Levels", BCP 14, RFC 2119, March 1997.

RFC2460 Deering, S. and R. Hinden, "Internet Protocol, Version 6 

          (IPv6) Specification", RFC 2460, December 1998.

RFC2671 Vixie, P., "Extension Mechanisms for DNS (EDNS0)", 

          RFC 2671, August 1999.

RFC2710 Deering, S., Fenner, W., and B. Haberman, "Multicast 

          Listener Discovery (MLD) for IPv6", RFC 2710,
          October 1999.

RFC2711 Partridge, C. and A. Jackson, "IPv6 Router Alert Option", 

          RFC 2711, October 1999.

RFC3315 Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 

          and M. Carney, "Dynamic Host Configuration Protocol for
          IPv6 (DHCPv6)", RFC 3315, July 2003.

RFC3484 Draves, R., "Default Address Selection for Internet 

          Protocol version 6 (IPv6)", RFC 3484, February 2003.

RFC3590 Haberman, B., "Source Address Selection for the Multicast 

          Listener Discovery (MLD) Protocol", RFC 3590,
          September 2003.

RFC3596 Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 

          "DNS Extensions to Support IP Version 6", RFC 3596,
          October 2003.

RFC3736 Droms, R., "Stateless Dynamic Host Configuration Protocol 

          (DHCP) Service for IPv6", RFC 3736, April 2004.

RFC3810 Vida, R. and L. Costa, "Multicast Listener Discovery 

          Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.

RFC4033 Arends, R., Austein, R., Larson, M., Massey, D., and S. 

          Rose, "DNS Security Introduction and Requirements",
          RFC 4033, March 2005.

RFC4034 Arends, R., Austein, R., Larson, M., Massey, D., and S. 

          Rose, "Resource Records for the DNS Security Extensions",
          RFC 4034, March 2005.

RFC4035 Arends, R., Austein, R., Larson, M., Massey, D., and S. 

          Rose, "Protocol Modifications for the DNS Security
          Extensions", RFC 4035, March 2005.

RFC4213 Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 

          for IPv6 Hosts and Routers", RFC 4213, October 2005.

RFC4291 Hinden, R. and S. Deering, "IP Version 6 Addressing 

          Architecture", RFC 4291, February 2006.

RFC4292 Haberman, B., "IP Forwarding Table MIB", RFC 4292, 

          April 2006.

RFC4293 Routhier, S., "Management Information Base for the 

          Internet Protocol (IP)", RFC 4293, April 2006.

RFC4301 Kent, S. and K. Seo, "Security Architecture for the 

          Internet Protocol", RFC 4301, December 2005.

RFC4303 Kent, S., "IP Encapsulating Security Payload (ESP)", 

          RFC 4303, December 2005.

RFC4307 Schiller, J., "Cryptographic Algorithms for Use in the 

          Internet Key Exchange Version 2 (IKEv2)", RFC 4307,
          December 2005.

RFC4311 Hinden, R. and D. Thaler, "IPv6 Host-to-Router Load 

          Sharing", RFC 4311, November 2005.

RFC4443 Conta, A., Deering, S., and M. Gupta, "Internet Control 

          Message Protocol (ICMPv6) for the Internet Protocol
          Version 6 (IPv6) Specification", RFC 4443, March 2006.

RFC4604 Holbrook, H., Cain, B., and B. Haberman, "Using Internet 

          Group Management Protocol Version 3 (IGMPv3) and Multicast
          Listener Discovery Protocol Version 2 (MLDv2) for Source-
          Specific Multicast", RFC 4604, August 2006.

RFC4607 Holbrook, H. and B. Cain, "Source-Specific Multicast for 

          IP", RFC 4607, August 2006.

RFC4835 Manral, V., "Cryptographic Algorithm Implementation 

          Requirements for Encapsulating Security Payload (ESP) and
          Authentication Header (AH)", RFC 4835, April 2007.

RFC4861 Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 

          "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
          September 2007.

RFC4862 Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 

          Address Autoconfiguration", RFC 4862, September 2007.

RFC4941 Narten, T., Draves, R., and S. Krishnan, "Privacy 

          Extensions for Stateless Address Autoconfiguration in
          IPv6", RFC 4941, September 2007.

RFC5095 Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 

          of Type 0 Routing Headers in IPv6", RFC 5095,
          December 2007.

RFC5453 Krishnan, S., "Reserved IPv6 Interface Identifiers", 

          RFC 5453, February 2009.

RFC5722 Krishnan, S., "Handling of Overlapping IPv6 Fragments", 

          RFC 5722, December 2009.

RFC5790 Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 

          Group Management Protocol Version 3 (IGMPv3) and Multicast
          Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790,
          February 2010.

RFC5942 Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet 

          Model: The Relationship between Links and Subnet
          Prefixes", RFC 5942, July 2010.

RFC5952 Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 

          Address Text Representation", RFC 5952, August 2010.

RFC5996 Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 

          "Internet Key Exchange Protocol Version 2 (IKEv2)",
          RFC 5996, September 2010.

RFC6106 Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 

          "IPv6 Router Advertisement Options for DNS Configuration",
          RFC 6106, November 2010.

RFC6204 Singh, H., Beebee, W., Donley, C., Stark, B., and O. 

          Troan, "Basic Requirements for IPv6 Customer Edge
          Routers", RFC 6204, April 2011.

RFC6437 Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 

          "IPv6 Flow Label Specification", RFC 6437, November 2011.

17.2. Informative References

[DODv6] DISR IPv6 Standards Technical Working Group, "DoD IPv6 

          Standard Profiles For IPv6 Capable Products Version 5.0",
          July 2010,
          <http://jitc.fhu.disa.mil/apl/ipv6/pdf/disr_ipv6_50.pdf>.

[POSIX] IEEE, "IEEE Std. 1003.1-2008 Standard for Information 

          Technology -- Portable Operating System Interface (POSIX),
          ISO/IEC 9945:2009", <http://www.ieee.org>.

RFC0793 Postel, J., "Transmission Control Protocol", STD 7, 

          RFC 793, September 1981.

RFC2205 Braden, B., Zhang, L., Berson, S., Herzog, S., and S. 

          Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
          Functional Specification", RFC 2205, September 1997.

RFC2464 Crawford, M., "Transmission of IPv6 Packets over Ethernet 

          Networks", RFC 2464, December 1998.

RFC2491 Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 

          over Non-Broadcast Multiple Access (NBMA) networks",
          RFC 2491, January 1999.

RFC2492 Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 

          Networks", RFC 2492, January 1999.

RFC2590 Conta, A., Malis, A., and M. Mueller, "Transmission of 

          IPv6 Packets over Frame Relay Networks Specification",
          RFC 2590, May 1999.

RFC2675 Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms", 

          RFC 2675, August 1999.

RFC3146 Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets 

          over IEEE 1394 Networks", RFC 3146, October 2001.

RFC3363 Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T. 

          Hain, "Representing Internet Protocol version 6 (IPv6)
          Addresses in the Domain Name System (DNS)", RFC 3363,
          August 2002.

RFC3493 Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 

          Stevens, "Basic Socket Interface Extensions for IPv6",
          RFC 3493, February 2003.

RFC3542 Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, 

          "Advanced Sockets Application Program Interface (API) for
          IPv6", RFC 3542, May 2003.

RFC3678 Thaler, D., Fenner, B., and B. Quinn, "Socket Interface 

          Extensions for Multicast Source Filters", RFC 3678,
          January 2004.

RFC3776 Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to 

          Protect Mobile IPv6 Signaling Between Mobile Nodes and
          Home Agents", RFC 3776, June 2004.

RFC3971 Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure 

          Neighbor Discovery (SEND)", RFC 3971, March 2005.

RFC3972 Aura, T., "Cryptographically Generated Addresses (CGA)", 

          RFC 3972, March 2005.

RFC4191 Draves, R. and D. Thaler, "Default Router Preferences and 

          More-Specific Routes", RFC 4191, November 2005.

RFC4302 Kent, S., "IP Authentication Header", RFC 4302, 

          December 2005.

RFC4338 DeSanti, C., Carlson, C., and R. Nixon, "Transmission of 

          IPv6, IPv4, and Address Resolution Protocol (ARP) Packets
          over Fibre Channel", RFC 4338, January 2006.

RFC4380 Huitema, C., "Teredo: Tunneling IPv6 over UDP through 

          Network Address Translations (NATs)", RFC 4380,
          February 2006.

RFC4429 Moore, N., "Optimistic Duplicate Address Detection (DAD) 

          for IPv6", RFC 4429, April 2006.

RFC4584 Chakrabarti, S. and E. Nordmark, "Extension to Sockets API 

          for Mobile IPv6", RFC 4584, July 2006.

RFC4821 Mathis, M. and J. Heffner, "Packetization Layer Path MTU 

          Discovery", RFC 4821, March 2007.

RFC4877 Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 

          IKEv2 and the Revised IPsec Architecture", RFC 4877,
          April 2007.

RFC4884 Bonica, R., Gan, D., Tappan, D., and C. Pignataro, 

          "Extended ICMP to Support Multi-Part Messages", RFC 4884,
          April 2007.

RFC4944 Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 

          "Transmission of IPv6 Packets over IEEE 802.15.4
          Networks", RFC 4944, September 2007.

RFC5006 Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 

          "IPv6 Router Advertisement Option for DNS Configuration",
          RFC 5006, September 2007.

RFC5014 Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 

          Socket API for Source Address Selection", RFC 5014,
          September 2007.

RFC5072 S.Varada, Haskins, D., and E. Allen, "IP Version 6 over 

          PPP", RFC 5072, September 2007.

RFC5121 Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S. 

          Madanapalli, "Transmission of IPv6 via the IPv6
          Convergence Sublayer over IEEE 802.16 Networks", RFC 5121,
          February 2008.

RFC5555 Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and 

          Routers", RFC 5555, June 2009.

RFC6275 Perkins, C., Johnson, D., and J. Arkko, "Mobility Support 

          in IPv6", RFC 6275, July 2011.

[USGv6] National Institute of Standards and Technology, "A Profile 

          for IPv6 in the U.S. Government - Version 1.0", July 2008,
          <http://www.antd.nist.gov/usgv6/usgv6-v1.pdf>.

Authors' Addresses

Ed Jankiewicz SRI International, Inc. 333 Ravenswood Ave. Menlo Park, CA 94025 USA

Phone: +1 443 502 5815 EMail: [email protected]

John Loughney Nokia 200 South Mathilda Ave. Sunnyvale, CA 94086 USA

Phone: +1 650 283 8068 EMail: [email protected]

Thomas Narten IBM Corporation 3039 Cornwallis Ave. PO Box 12195 Research Triangle Park, NC 27709-2195 USA

Phone: +1 919 254 7798 EMail: [email protected]

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