Internet Engineering Task Force T. Chown
Internet-Draft Jisc
Obsoletes: 6434 (if approved) J. Loughney
Intended status: Informational Nokia
Expires: November 3, 2017 T. Winters
University of New Hampshire
May 2, 2017

IPv6 Node Requirements


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 6434, and in turn RFC 4294.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on November 3, 2017.

Copyright Notice

Copyright (c) 2017 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 ( 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.

Table of Contents

1. 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 [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].

1.1. 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.

1.2. 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.

**BIS We will need to refer to 2460-bis, as well as 1981-bis and 4291-bis, throughout this document. These are still in flux, but we will know the final versions of these documents before this -bis is published, so can adapt text here once those updates are complete.**

2. 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].

3. 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

4. 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]
IPv6 over IEEE 802.15.4 Networks [RFC4944]

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]

**BIS Do we want a small section somewhere on UDP IPv6 tunneling, and issues like RFC 6935, or 6936?**

5. IP Layer

5.1. Internet Protocol Version 6 - RFC 2460

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

**BIS Again, update for RFC 2460 -bis **

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].

[RFC6946] discusses IPv6 atomic fragments, and recommends that IPv6 atomic fragments are processed independently of any other fragments, to protect against fragmenttation-based attacks. [RFC8021] goes further and recommends the deprecation of atomic fragments. Nodes thus MUST not generate atomic fragments.

To mitigate a variety of potential attacks, nodes SHOULD avoid using predictable fragment Identification values in Fragment Headers, as discussed in [RFC7739].

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.

Should a new type of Extension Header need to be defined, its format MUST follow the consistent format described in Section 4 of [RFC6564].

Further, [RFC7045] adds specific requirements for processing of Extension Headers, in particular that any forwarding node along an IPv6 packet's path, which forwards the packet for any reason, SHOULD do so regardless of any extension headers that are present.

[RFC7112] discusses issues with oversized IPv6 Extension Header chains, and states that when a node fragments an IPv6 datagram, it MUST include the entire IPv6 Header Chain in the First Fragment.

**BIS Wait to see outcome of insertion of EHs issue in 2460-bis, and re-state here? **

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.

5.2. 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.

[RFC7048] discusses NUD, in particular cases where it behaves too impatiently. It states that if a node transmits more than a certain number of packets, then it SHOULD use the exponential backoff of the retransmit timer, up to a certain threshold point.

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.

[RFC7559] discusses packet loss resliency for Router Solicitations, and requires that nodes MUST use a specific exponential backoff algorithm for RS retransmissions.

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.

5.3. 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 [RFC7084] use RFC 4191 to advertise routes to certain local destinations. Consequently, nodes that will be deployed in SOHO environments SHOULD implement RFC 4191.

5.4. SEcure Neighbor Discovery (SEND) - RFC 3971

SEND [RFC3971] and Cryptographically Generated Addresses (CGAs) [RFC3972] provide a way to secure the message exchanges of Neighbor Discovery. SEND has the potential to address certain classes of spoofing attacks, but it does not provide specific protection for threats from off-link attackers. It requires relatively heavyweight provisioning, so is only likely to be used in scenarios where security considerations are particularly important.

There have been relatively few implementations of SEND in common operating systems and platforms, and thus deployment experience has been limited to date.

At this time, SEND is considered optional. Due to the complexity in deploying SEND, its deployment is only likely to be considered where nodes are operating in a particularly strict security environment.

5.5. 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.

5.6. Path MTU Discovery and Packet Size

5.6.1. 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.

**BIS Add note about 1280 MTU and UDP, as per Mark Andrews' comments in Berlin? **

5.7. 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.

**BIS Are these used? Do we need to modify the text for that? **

5.8. 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.

5.9. Addressing

5.9.1. IP Version 6 Addressing Architecture - RFC 4291

The IPv6 Addressing Architecture [RFC4291] MUST be supported.

**BIS Update to 4291-bis **

**BIS Add note on Why /64? RFC 7421, after the conclusion of the RFC4291-bis (lengthy!!!) discussions on the 64-bit IID topic. But no need for /127 p2p text RFC 6164. And no need for note on IID significance, as per RFC 7136. **

5.9.2. Host Address Availability Recommendations

Hosts may be configured with addresses through a variety of methods, including SLAAC, DHCPv6, or manual configuration.

[RFC7934] recommends that networks provide general-purpose end hosts with multiple global IPv6 addresses when they attach, and it describes the benefits of and the options for doing so. There are, for example, benefits to multiple addresses for privacy reasons, or to assigning hosts a whole /64 to avoid the need for host-based NAT.

5.9.3. IPv6 Stateless Address Autoconfiguration - RFC 4862

Hosts MUST support IPv6 Stateless Address Autoconfiguration as defined in either [RFC4862] or [RFC7217]. It is recommended that, unless there is a specific requirement for MAC addresses to be embedded in an IID, nodes follow the procedure in RFC7217 to generate SLAAC-based addresses. Addresses generated through RFC7217 will be the same whenever a given device (re)appears on the same subnet (with a specific IPv6 prefix), but the IID will vary on each subnet visited.

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.

[RFC7527] discusses enhanced DAD, and describes an algorithm to automate the detection of looped back IPv6 ND messages used by DAD. Nodes SHOULD implement this behaviour where such detection is beneficial.

5.9.4. Privacy Extensions for Address Configuration in IPv6 - RFC 4941

A node using Stateless Address Autoconfiguration [RFC4862] to form a globally unique IPv6 address using its MAC address to generate the IID will see that IID remain the same on any visited network, even though the network prefix part changes. Thus it is possible for 3rd party devices such nodes communicate with to track the activities of the node as it moves around the network. Privacy Extensions for Stateless Address Autoconfiguration [RFC4941] address this concern by allowing nodes to configure an additional temporary address where the IID is effectively randomly generated. Privacy addresses are then used as source addresses for new communications initiated by the node.

[RFC7721] discusses general privacy issues with IPv6 addressing.

RFC 4941 SHOULD be supported. In some scenarios, such as dedicated servers in a data center, it provides limited or no benefit, or may complicate network management. Thus devices implementing this specification MUST provide a way for the end user to explicitly enable or disable the use of such temporary addresses.

Note that RFC4941 can be used independently of traditional SLAAC, or of RFC7217-based SLAAC.

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.

5.9.5. Default Address Selection for IPv6 - RFC 6724

IPv6 nodes will invariably have multiple addresses configured simultaneously, and thus will need to choose which addresses to use for which communications. The rules specified in the Default Address Selection for IPv6 [RFC6724] document MUST be implemented.

5.9.6. 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 stateful 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

**BIS MLDv2 only?

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 Lightweight 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.

6. DHCP versus Router Advertisement Options for Host Configuration

**BIS this section probably needs rewriting **

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.

7. DNS and DHCP

7.1. 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 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].

A6 Resource Records, which were only ever defined with Experimental status in [RFC3363], are now classified as Historic, as per [RFC6563].

**BIS Add DNS-SD? **

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

7.2.1. Other Configuration Information

IPv6 nodes use DHCP [RFC3315] to obtain address configuration information (see Section 5.9.6) 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.

7.2.2. 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. There is no defined DHCPv6 Gateway option.

7.3. 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].

8. IPv4 Support and Transition

IPv6 nodes MAY support IPv4.

8.1. Transition Mechanisms

8.1.1. Basic Transition Mechanisms for IPv6 Hosts and Routers - RFC 4213

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

9. Application Support

9.1. 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].

9.2. 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 [RFC6724].

"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. Cellular Host

IPv6 for 3GPP [RFC7066] lists IPv6 Functionalities that need to be implemented above and beyond the recommendations in this document. Additionally a 3GPP IPv6 Host MAY implement [RFC7278] for delivering IPv6 prefixes on the LAN link.

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.

**BIS Add note on security in IPv4-only networks? RFC 7123? Relevant? **

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.

**BIS update to 7321bis**

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].

**BIS update to 4307bis**

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; for the case of typical home routers, [RFC7084] defines basic requirements for customer edge routers.

**BIS Sync here with work by John Brzozowski et al. in draft-ali-ipv6rtr-reqs-02**

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., [RFC7084]). 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" [RFC7084] 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.

**BIS This is a little thin. Add Netconf, restconf, yang models? **

**BIS add the network polling/syslod nd for none DHCPv6 network tracking.**

13.1. Management Information Base (MIB) Modules

**BIS Address MIB Obsolete draft

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. Constrained Devices

**BIS Should we add notes on constrained devices, and power efficiency here in a new section? Talk about resource management in nodes. Low power operation.

15. 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.

16. Authors and Acknowledgments

16.1. Authors and Acknowledgments (Current Document)

For this version of the IPv6 Node Requirements document, the authors would like to thank **BIS Add new acknowledgements for significant comments ** for their contributions.

16.2. Authors and Acknowledgments from RFC 6434

Ed Jankiewicz and Thomas Narten were named authors of the previous iteration of this document, RFC6434.

For this version of the document, the authors thanked Hitoshi Asaeda, Brian Carpenter, Tim Chown, Ralph Droms, Sheila Frankel, Sam Hartman, Bob Hinden, Paul Hoffman, Pekka Savola, Yaron Sheffer, and Dave Thaler.

16.3. Authors and Acknowledgments from RFC 4294

   Jari Arkko
   Marc Blanchet
   Samita Chakrabarti
   Alain Durand
   Gerard Gastaud
   Jun-ichiro Itojun Hagino
   Atsushi Inoue
   Masahiro Ishiyama
   John Loughney
   Rajiv Raghunarayan
   Shoichi Sakane
   Dave Thaler
   Juha Wiljakka

The original version of this document (RFC 4294) was written by the IPv6 Node Requirements design team:

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.

17. Appendix: Changes from RFC 6434

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. Added 6LoWPAN to link layers
  2. Removed DOD IPv6 Profile updates
  3. Removed IPv6 Mobility RFC6275

18. 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.

19. References

19.1. Normative References

[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987.
[RFC1981] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, December 1998.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671, DOI 10.17487/RFC2671, August 1999.
[RFC2710] Deering, S., Fenner, W. and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, DOI 10.17487/RFC2710, October 1999.
[RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", RFC 2711, DOI 10.17487/RFC2711, 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, DOI 10.17487/RFC3315, July 2003.
[RFC3590] Haberman, B., "Source Address Selection for the Multicast Listener Discovery (MLD) Protocol", RFC 3590, DOI 10.17487/RFC3590, September 2003.
[RFC3596] Thomson, S., Huitema, C., Ksinant, V. and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, DOI 10.17487/RFC3596, October 2003.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6", RFC 3736, DOI 10.17487/RFC3736, April 2004.
[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, DOI 10.17487/RFC3810, June 2004.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D. and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, DOI 10.17487/RFC4033, March 2005.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D. and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, March 2005.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D. and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 4213, DOI 10.17487/RFC4213, October 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006.
[RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, DOI 10.17487/RFC4292, April 2006.
[RFC4293] Routhier, S., "Management Information Base for the Internet Protocol (IP)", RFC 4293, DOI 10.17487/RFC4293, April 2006.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, December 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, DOI 10.17487/RFC4303, December 2005.
[RFC4307] Schiller, J., "Cryptographic Algorithms for Use in the Internet Key Exchange Version 2 (IKEv2)", RFC 4307, DOI 10.17487/RFC4307, December 2005.
[RFC4311] Hinden, R. and D. Thaler, "IPv6 Host-to-Router Load Sharing", RFC 4311, DOI 10.17487/RFC4311, 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, DOI 10.17487/RFC4443, 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, DOI 10.17487/RFC4604, August 2006.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for IP", RFC 4607, DOI 10.17487/RFC4607, August 2006.
[RFC4861] Narten, T., Nordmark, E., Simpson, W. and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007.
[RFC4862] Thomson, S., Narten, T. and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, DOI 10.17487/RFC4862, September 2007.
[RFC4835] Manral, V., "Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload (ESP) and Authentication Header (AH)", RFC 4835, DOI 10.17487/RFC4835, April 2007.
[RFC4941] Narten, T., Draves, R. and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007.
[RFC5095] Abley, J., Savola, P. and G. Neville-Neil, "Deprecation of Type 0 Routing Headers in IPv6", RFC 5095, DOI 10.17487/RFC5095, December 2007.
[RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers", RFC 5453, DOI 10.17487/RFC5453, February 2009.
[RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments", RFC 5722, DOI 10.17487/RFC5722, 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, DOI 10.17487/RFC5790, February 2010.
[RFC5942] Singh, H., Beebee, W. and E. Nordmark, "IPv6 Subnet Model: The Relationship between Links and Subnet Prefixes", RFC 5942, DOI 10.17487/RFC5942, July 2010.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 Address Text Representation", RFC 5952, DOI 10.17487/RFC5952, August 2010.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y. and P. Eronen, "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5996, DOI 10.17487/RFC5996, September 2010.
[RFC6106] Jeong, J., Park, S., Beloeil, L. and S. Madanapalli, "IPv6 Router Advertisement Options for DNS Configuration", RFC 6106, DOI 10.17487/RFC6106, November 2010.
[RFC6437] Amante, S., Carpenter, B., Jiang, S. and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, November 2011.
[RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J. and M. Bhatia, "A Uniform Format for IPv6 Extension Headers", RFC 6564, DOI 10.17487/RFC6564, April 2012.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A. and T. Chown, "Default Address Selection for Internet Protocol Version 6 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012.
[RFC6946] Gont, F., "Processing of IPv6 "Atomic" Fragments", RFC 6946, DOI 10.17487/RFC6946, May 2013.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing of IPv6 Extension Headers", RFC 7045, DOI 10.17487/RFC7045, December 2013.
[RFC7048] Nordmark, E. and I. Gashinsky, "Neighbor Unreachability Detection Is Too Impatient", RFC 7048, DOI 10.17487/RFC7048, January 2014.
[RFC7112] Gont, F., Manral, V. and R. Bonica, "Implications of Oversized IPv6 Header Chains", RFC 7112, DOI 10.17487/RFC7112, January 2014.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque Interface Identifiers with IPv6 Stateless Address Autoconfiguration (SLAAC)", RFC 7217, DOI 10.17487/RFC7217, April 2014.
[RFC7527] Asati, R., Singh, H., Beebee, W., Pignataro, C., Dart, E. and W. George, "Enhanced Duplicate Address Detection", RFC 7527, DOI 10.17487/RFC7527, April 2015.
[RFC7559] Krishnan, S., Anipko, D. and D. Thaler, "Packet-Loss Resiliency for Router Solicitations", RFC 7559, DOI 10.17487/RFC7559, May 2015.
[RFC7739] Gont, F., "Security Implications of Predictable Fragment Identification Values", RFC 7739, DOI 10.17487/RFC7739, February 2016.
[RFC8021] Gont, F., Liu, W. and T. Anderson, "Generation of IPv6 Atomic Fragments Considered Harmful", RFC 8021, DOI 10.17487/RFC8021, January 2017.

19.2. Informative References

[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, DOI 10.17487/RFC0793, September 1981.
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, September 1997.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998.
[RFC2491] Armitage, G., Schulter, P., Jork, M. and G. Harter, "IPv6 over Non-Broadcast Multiple Access (NBMA) networks", RFC 2491, DOI 10.17487/RFC2491, January 1999.
[RFC2492] Armitage, G., Schulter, P. and M. Jork, "IPv6 over ATM Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999.
[RFC2590] Conta, A., Malis, A. and M. Mueller, "Transmission of IPv6 Packets over Frame Relay Networks Specification", RFC 2590, DOI 10.17487/RFC2590, May 1999.
[RFC2675] Borman, D., Deering, S. and R. Hinden, "IPv6 Jumbograms", RFC 2675, DOI 10.17487/RFC2675, August 1999.
[RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146, 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, DOI 10.17487/RFC3363, August 2002.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J. and W. Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493, DOI 10.17487/RFC3493, February 2003.
[RFC3542] Stevens, W., Thomas, M., Nordmark, E. and T. Jinmei, "Advanced Sockets Application Program Interface (API) for IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003.
[RFC3678] Thaler, D., Fenner, B. and B. Quinn, "Socket Interface Extensions for Multicast Source Filters", RFC 3678, DOI 10.17487/RFC3678, January 2004.
[RFC6275] Perkins, C., Johnson, D. and J. Arkko, "Mobility Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 2011.
[RFC3971] Arkko, J., Kempf, J., Zill, B. and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, DOI 10.17487/RFC3971, March 2005.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, DOI 10.17487/RFC3972, March 2005.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, November 2005.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302, DOI 10.17487/RFC4302, 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, DOI 10.17487/RFC4338, January 2006.
[RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network Address Translations (NATs)", RFC 4380, DOI 10.17487/RFC4380, February 2006.
[RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006.
[RFC4584] Chakrabarti, S. and E. Nordmark, "Extension to Sockets API for Mobile IPv6", RFC 4584, DOI 10.17487/RFC4584, July 2006.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007.
[RFC4884] Bonica, R., Gan, D., Tappan, D. and C. Pignataro, "Extended ICMP to Support Multi-Part Messages", RFC 4884, DOI 10.17487/RFC4884, April 2007.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J. and D. Culler, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007.
[RFC5006] Jeong, J., Park, S., Beloeil, L. and S. Madanapalli, "IPv6 Router Advertisement Option for DNS Configuration", RFC 5006, DOI 10.17487/RFC5006, September 2007.
[RFC5014] Nordmark, E., Chakrabarti, S. and J. Laganier, "IPv6 Socket API for Source Address Selection", RFC 5014, DOI 10.17487/RFC5014, September 2007.
[RFC5072] Varada, S., Haskins, D. and E. Allen, "IP Version 6 over PPP", RFC 5072, DOI 10.17487/RFC5072, 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, DOI 10.17487/RFC5121, February 2008.
[RFC6563] Jiang, S., Conrad, D. and B. Carpenter, "Moving A6 to Historic Status", RFC 6563, DOI 10.17487/RFC6563, March 2012.
[RFC7066] Korhonen, J., Arkko, J., Savolainen, T. and S. Krishnan, "IPv6 for Third Generation Partnership Project (3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066, November 2013.
[RFC7084] Singh, H., Beebee, W., Donley, C. and B. Stark, "Basic Requirements for IPv6 Customer Edge Routers", RFC 7084, DOI 10.17487/RFC7084, November 2013.
[RFC7278] Byrne, C., Drown, D. and A. Vizdal, "Extending an IPv6 /64 Prefix from a Third Generation Partnership Project (3GPP) Mobile Interface to a LAN Link", RFC 7278, DOI 10.17487/RFC7278, June 2014.
[RFC7721] Cooper, A., Gont, F. and D. Thaler, "Security and Privacy Considerations for IPv6 Address Generation Mechanisms", RFC 7721, DOI 10.17487/RFC7721, March 2016.
[RFC7934] Colitti, L., Cerf, V., Cheshire, S. and D. Schinazi, "Host Address Availability Recommendations", BCP 204, RFC 7934, DOI 10.17487/RFC7934, July 2016.
[POSIX] IEEE, "IEEE Std. 1003.1-2008 Standard for Information Technology -- Portable Operating System Interface (POSIX), ISO/IEC 9945:2009"
[USGv6] National Institute of Standards and Technology, "A Profile for IPv6 in the U.S. Government - Version 1.0", July 2008.

Authors' Addresses

Tim Chown Jisc Lumen House, Library Avenue Harwell Oxford, Didcot, OX11 0SG United Kingdom EMail:
John Loughney Nokia 200 South Mathilda Ave. Sunnyvale, CA, 94086 USA Phone: +1 650 283 8068 EMail:
Timothy Winters University of New Hampshire InterOperability Laboratory Durham, NH United States EMail: