IPv6 transition mechanisms |
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6rd is a mechanism to facilitate IPv6 rapid deployment across IPv4 infrastructures of Internet service providers (ISPs).
The protocol is derived from 6to4, a preexisting mechanism to transfer IPv6 packets over the IPv4 network, with the significant change that it operates entirely within the end-user's ISP network, thus avoiding the major architectural problems inherent in the design of 6to4. The name 6rd is a reference to both the rapid deployments of IPv6 it enables, and, informally, the initials (RD) of its inventor, Rémi Després.
A description of 6rd principles and their first application by the ISP Free is published in RFC 5569, [1] The 6rd specification prepared for standardization in the IETF is available as RFC 5969. [2]
In November 2007, Rémi Després [3] — who was one of the creators of the Transpac data network in France in the 1970s — proposed to Free, the second largest ISP in France, to use the 6rd mechanism he had invented to rapidly deploy IPv6. While Free had until then no short-term plan to offer IPv6 service, Rani Assaf, the CTO of Free, immediately decided to implement the solution. Five weeks later, [4] with due marketing approval and operational validation, the press release [5] announcing that IPv6 was available to Free's customers was issued.
The first draft describing the 6rd mechanism and Free's deployment was submitted to IETF on 9 February 2008. [6] After improvements, it was published on 24 January 2010 as informational RFC 5569. [1]
In March 2010, a Working Group of the IETF approved that its latest draft on 6rd should become, after some more modifications, a standards-track RFC. In August 2010, the standards-track RFC 5969 [2] was published. In October 2010 Comcast made 6rd software for home gateway devices available via open source for free. [7]
6to4 works by relaying traffic between native IPv6 and IPv4 using relay servers which advertise common IPv4 and IPv6 prefixes to networks they are prepared to provide relay services for, but there is no guarantee that all native IPv6 hosts have a working route toward such a relay. Because of this, a 6to4 host is not guaranteed to be reachable by all native IPv6 hosts. Even when a relay is available, it is often operated by a third party who has no obligation to maintain a good quality of service as traffic grows. 6rd changes this model by making each ISP use one of its own IPv6 prefixes instead of the special 2002::/16 prefix standardized for 6to4, [8] so a provider is guaranteed that its 6rd hosts will be reachable from all native IPv6 hosts that can reach their IPv6 network. Because the relay is fully under the ISP's control, it keeps full responsibility for the quality of service for its customers.
Because 6rd relays can only be used by a limited set of hosts that are all under the control of the same administrative entity, it also reduces the scope for traffic anonymization attacks such as those possible with 6to4. [2]
The simplest 6rd deployment, which uses 32 bits of IPv6 address space to map the entire IPv4 address space, consumes more address space than typical with IPv6 natively supported in all ISP routers. This can be mitigated by omitting redundant parts of the IPv4 address space, and in some cases by deploying multiple 6rd domains. [1] [2]
The default allocation of IPv6 space by a regional Internet registry (RIR) is a 32-bit prefix. Since it takes 32 bits to map an IPv4 address with 6rd, this implies that an ISP would only be able to allocate 64-bit IPv6 prefixes to its customers if it were to use entire IPv4 addresses. 6rd, however, allows any redundant part of an IPv4 address to be discarded: For example, if the IPv4 addresses that an ISP issues to its customers all share the same first eighteen bits, a 6rd prefix only need include the remaining fourteen bits. Without this flexibility, Free originally assigned 64-bit IPv6 prefixes to its customers but was able to assign them shorter prefixes once it obtained a larger allocation of IPv6 space (a 26-bit prefix) from the RIPE NCC.
This section needs to be updated.(February 2017) |
An Internet Protocol address is a numerical label such as 192.0.2.1 that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing.
Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version deployed for production on SATNET in 1982 and on the ARPANET in January 1983. It is still used to route most Internet traffic today, even with the ongoing deployment of Internet Protocol version 6 (IPv6), its successor.
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A Martian packet is an IP packet seen on the public Internet that contains a source or destination address that is reserved for special use by the Internet Assigned Numbers Authority (IANA) as defined in RFC 1812, Appendix B Glossary. On the public Internet, such a packet either has a spoofed source address, and it cannot actually originate as claimed, or the packet cannot be delivered. The requirement to filter these packets is found in RFC 1812, Section 5.3.7.
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6to4 is an Internet transition mechanism for migrating from Internet Protocol version 4 (IPv4) to version 6 (IPv6) and a system that allows IPv6 packets to be transmitted over an IPv4 network without the need to configure explicit tunnels. Special relay servers are also in place that allow 6to4 networks to communicate with native IPv6 networks.
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In the Internet addressing architecture, the Internet Engineering Task Force (IETF) and the Internet Assigned Numbers Authority (IANA) have reserved various Internet Protocol (IP) addresses for special purposes.
An IPv6 transition mechanism is a technology that facilitates the transitioning of the Internet from the Internet Protocol version 4 (IPv4) infrastructure in use since 1983 to the successor addressing and routing system of Internet Protocol Version 6 (IPv6). As IPv4 and IPv6 networks are not directly interoperable, transition technologies are designed to permit hosts on either network type to communicate with any other host.
IP networks are divided logically into subnetworks. Computers in the same subnetwork have the same address prefix. For example, in a typical home network with legacy Internet Protocol version 4, the network prefix would be something like 192.168.1.0/24, as expressed in CIDR notation.
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An Internet Protocol version 6 address is a numeric label that is used to identify and locate a network interface of a computer or a network node participating in a computer network using IPv6. IP addresses are included in the packet header to indicate the source and the destination of each packet. The IP address of the destination is used to make decisions about routing IP packets to other networks.
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NAT64 is an IPv6 transition mechanism that facilitates communication between IPv6 and IPv4 hosts by using a form of network address translation (NAT). The NAT64 gateway is a translator between IPv4 and IPv6 protocols, for which function it needs at least one IPv4 address and an IPv6 network segment comprising a 32-bit address space. The "well-known prefix" reserved for this service is 64:ff9b::/96.
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Rémi Després is a French engineer and entrepreneur known for his contributions on data networking.
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