NAT64

On networks providing IPv4-IPv6 translation (RFC 7915), hosts and other endpoints need to know the IPv6 prefix(es) used for translation (the NAT64 prefix (RFC 6052)). This document provides guidelines for NAT64 prefix discovery, specifically recommending obtaining the NAT64 prefix from the Router Advertisement option (RFC 8781) when available.

NAT64 (Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers) allows client devices using IPv6 to communicate with servers that have only IPv4 connectivity.

The specification for how a client discovers its local network's NAT64 prefix (RFC 7050) defines the special name 'ipv4only.arpa' for this purpose. However, in its Domain Name Reservation Considerations section (Section 8.1), that specification (RFC 7050) indicates that the name actually has no particularly special properties that would require special handling.

Consequently, despite the well-articulated special purpose of the name, 'ipv4only.arpa' was not recorded in the Special-Use Domain Names registry as a name with special properties.

This document updates RFC 7050. It describes the special treatment required and formally declares the special properties of the name. It also adds similar declarations for the corresponding reverse mapping names.

This document describes how Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers (NAT64) (including 464XLAT) can be deployed in an IPv6 network -- whether it's cellular ISP, broadband ISP, or enterprise -- and the possible optimizations. This document also discusses issues to be considered when having IPv6-only connectivity, such as: a) DNS64, b) applications or devices that use literal IPv4 addresses or non-IPv6-compliant APIs, and c) IPv4-only hosts or applications.

This document defines a YANG module for the Network Address Translation (NAT) function.

Network Address Translation from IPv4 to IPv4 (NAT44), Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers (NAT64), customer-side translator (CLAT), Stateless IP/ICMP Translation (SIIT), Explicit Address Mappings (EAM) for SIIT, IPv6-to-IPv6 Network Prefix Translation (NPTv6), and Destination NAT are covered in this document.

Many communication protocols operating over the modern Internet use hostnames. These often resolve to multiple IP addresses, each of which may have different performance and connectivity characteristics. Since specific addresses or address families (IPv4 or IPv6) may be blocked, broken, or sub-optimal on a network, clients that attempt multiple connections in parallel have a chance of establishing a connection more quickly. This document specifies requirements for algorithms that reduce this user-visible delay and provides an example algorithm, referred to as "Happy Eyeballs". This document obsoletes the original algorithm description in RFC 6555.

This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use within domains that enable IPv4/IPv6 translation mechanisms.

Benchmarking methodologies that address the performance of network interconnect devices that are IPv4- or IPv6-capable exist, but the IPv6 transition technologies are outside of their scope. This document provides complementary guidelines for evaluating the performance of IPv6 transition technologies. More specifically, this document targets IPv6 transition technologies that employ encapsulation or translation mechanisms, as dual-stack nodes can be tested using the recommendations of RFCs 2544 and 5180. The methodology also includes a metric for benchmarking load scalability.

This document specifies a solution for the delivery of IPv4 multicast services to IPv4 clients over an IPv6 multicast network. The solution relies upon a stateless IPv4-in-IPv6 encapsulation scheme and uses an IPv6 multicast distribution tree to deliver IPv4 multicast traffic. The solution is particularly useful for the delivery of multicast service offerings to customers serviced by Dual-Stack Lite (DS-Lite).

This document defines a Dynamic Host Configuration Protocol version 6 (DHCPv6) Option for multicast IPv4 service continuity solutions, which is used to carry the IPv6 prefixes to be used to build unicast and multicast IPv4-embedded IPv6 addresses.

This document 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.

This document clarifies and updates several requirements of RFCs 4787, 5382, and 5508 based on operational and development experience. The focus of this document is Network Address Translation from IPv4 to IPv4 (NAT44).

This document updates RFCs 4787, 5382, and 5508.

This document specifies a new Port Control Protocol (PCP) functional element: the PCP proxy. The PCP proxy relays PCP requests received from PCP clients to upstream PCP server(s). A typical deployment usage of this function is to help establish successful PCP communications for PCP clients that cannot be configured with the address of a PCP server located more than one hop away.

This document summarizes NAT64 function deployment scenarios and operational experience. Both NAT64 Carrier-Grade NAT (NAT64-CGN) and NAT64 server Front End (NAT64-FE) are considered in this document.

This document defines a new Port Control Protocol (PCP) option to learn the IPv6 prefix(es) used by a PCP-controlled NAT64 device to build IPv4-converted IPv6 addresses. This option is needed for successful communications when IPv4 addresses are used in referrals.

This document describes a method for detecting the presence of DNS64 and for learning the IPv6 prefix used for protocol translation on an access network. The method depends on the existence of a well-known IPv4-only fully qualified domain name "ipv4only.arpa.". The information learned enables nodes to perform local IPv6 address synthesis and to potentially avoid NAT64 on dual-stack and multi-interface deployments.

Hosts and applications may benefit from learning if an IPv6 address is synthesized and if NAT64 and DNS64 are present in a network. This document analyzes all proposed solutions (known at the time of writing) for communicating whether the synthesis is taking place, what address format was used, and what IPv6 prefix was used by the NAT64 and DNS64. These solutions enable both NAT64 avoidance and local IPv6 address synthesis. The document concludes by recommending the standardization of the approach based on heuristic discovery.

Due to specific problems, Network Address Translation - Protocol Translation (NAT-PT) was deprecated by the IETF as a mechanism to perform IPv6-IPv4 translation. Since then, new efforts have been undertaken within IETF to standardize alternative mechanisms to perform IPv6-IPv4 translation. This document analyzes to what extent the new stateful translation mechanisms avoid the problems that caused the IETF to deprecate NAT-PT.

This document discusses our experiences from moving a small number of users to an IPv6-only network, with access to the IPv4-only parts of the Internet via a NAT64 device. The document covers practical experiences as well as roadblocks and opportunities for this type of a network setup. The document also makes some recommendations about where such networks are applicable and what should be taken into account in the network design. The document also discusses further work that is needed to make IPv6-only networking applicable in all environments. This document is not an Internet Standards Track specification; it is published for informational purposes.

The File Transfer Protocol (FTP) has a very long history, and despite the fact that today other options exist to perform file transfers, FTP is still in common use. As such, in situations where some client computers only have IPv6 connectivity while many servers are still IPv4-only and IPv6-to-IPv4 translators are used to bridge that gap, it is important that FTP is made to work through these translators to the best possible extent.

FTP has an active and a passive mode, both as original commands that are IPv4-specific and as extended, IP version agnostic commands. The only FTP mode that works without changes through an IPv6-to-IPv4 translator is extended passive. However, many existing FTP servers do not support this mode, and some clients do not ask for it. This document specifies a middlebox that may solve this mismatch. [STANDARDS-TRACK]

This document presents the China Education and Research Network (CERNET)'s IVI translation design and deployment for the IPv4/IPv6 coexistence and transition.

The IVI is a prefix-specific and stateless address mapping mechanism for "an IPv6 network to the IPv4 Internet" and "the IPv4 Internet to an IPv6 network" scenarios. In the IVI design, subsets of the ISP's IPv4 addresses are embedded in the ISP's IPv6 addresses, and the hosts using these IPv6 addresses can therefore communicate with the global IPv6 Internet directly and can communicate with the global IPv4 Internet via stateless translators. The communications can either be IPv6 initiated or IPv4 initiated. The IVI mechanism supports the end-to-end address transparency and incremental deployment. The IVI is an early design deployed in the CERNET as a reference for the IETF standard documents on IPv4/IPv6 stateless translation. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document describes stateful NAT64 translation, which allows IPv6-only clients to contact IPv4 servers using unicast UDP, TCP, or ICMP. One or more public IPv4 addresses assigned to a NAT64 translator are shared among several IPv6-only clients. When stateful NAT64 is used in conjunction with DNS64, no changes are usually required in the IPv6 client or the IPv4 server.

This document discusses the algorithmic translation of an IPv6 address to a corresponding IPv4 address, and vice versa, using only statically configured information. It defines a well-known prefix for use in algorithmic translations, while allowing organizations to also use network-specific prefixes when appropriate. Algorithmic translation is used in IPv4/IPv6 translators, as well as other types of proxies and gateways (e.g., for DNS) used in IPv4/IPv6 scenarios. [STANDARDS-TRACK]