Internet Protocol version 6 (IPv6) is the next-generation Internet Protocol version designated as the successor to IPv4, the first implementation used in the Internet and still in dominant use currently^[update]. It is an Internet Layer protocol for packet-switched internetworks. The main driving force for the redesign of Internet Protocol was the foreseeable IPv4 address exhaustion. IPv6 was defined in December 1998 by the Internet Engineering Task Force (IETF) with the publication of an Internet standard specification, RFC 2460.

IPv6 has a vastly larger address space than IPv4. This results from the use of a 128-bit address, whereas IPv4 uses only 32 bits. The new address space thus supports 2¹²⁸ (about 3.4×10³⁸) addresses. This expansion provides flexibility in allocating addresses and routing traffic and eliminates the primary need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.

IPv6 also implements new features that simplify aspects of address assignment (stateless address autoconfiguration) and network renumbering (prefix and router announcements) when changing Internet connectivity providers. The IPv6 subnet size has been standardized by fixing the size of the host identifier portion of an address to 64 bits to facilitate an automatic mechanism for forming the host identifier from Link Layer media addressing information (MAC address).

Network security is integrated into the design of the IPv6 architecture. Internet Protocol Security (IPsec) was originally developed for IPv6, but found widespread optional deployment first in IPv4 (into which it was back-engineered). The IPv6 specifications mandate IPsec implementation as a fundamental interoperability requirement.

In December 2008, despite marking its 10th anniversary as a Standards Track protocol, IPv6 was only in its infancy in terms of general worldwide deployment. A 2008 study^[1] by Google Inc. indicated that penetration was still less than one percent of Internet-enabled hosts in any country. IPv6 has been implemented on all major operating systems in use in commercial, business, and home consumer environments.^[2]

The Internet Protocol Suite
Application Layer
BGP · DHCP · DNS · FTP · GTP · HTTP · IMAP · IRC · Megaco · MGCP · NNTP · NTP · POP · RIP · RPC · RTP · RTSP · SDP · SIP · SMTP · SNMP · SOAP · SSH · Telnet · TLS/SSL · XMPP · (more)
Transport Layer
TCP · UDP · DCCP · SCTP · RSVP · ECN · (more)
Internet Layer
IP (IPv4, IPv6) · ICMP · ICMPv6 · IGMP · IPsec · (more)
Link Layer
ARP/InARP · NDP · OSPF · Tunnels (L2TP) · PPP · Media Access Control (Ethernet, DSL, ISDN, FDDI) · (more)
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Contents 1 Motivation and origins 1.1 IPv4 exhaustion 2 Features and differences from IPv4 2.1 Larger address space 2.2 Stateless address autoconfiguration 2.3 Multicast 2.4 Mandatory network layer security 2.5 Simplified processing by routers 2.6 Mobility 2.7 Options extensibility 2.8 Jumbograms 3 Packet format 3.1 Fixed header 3.2 Extension header 3.3 Payload 4 Addressing 5 Transition mechanisms 5.1 Dual stack 5.1.1 IPv4-mapped addresses 5.2 Tunneling 5.2.1 Automatic tunneling 5.2.2 Configured tunneling (6in4) 5.3 Proxying and translation for IPv6-only hosts 6 IPv6 readiness 6.1 Adoption issues 6.2 IPv6 conformance testing and evaluation 7 Deployment 8 Major announcements and availability 9 IPv6 network address translation 10 See also 11 References 12 External links

[edit] Motivation and origins

The first publicly used version of the Internet Protocol, Version 4 (IPv4), provides an addressing capability of about 4 billion addresses (2³²). This was deemed sufficient in the early design stages of the Internet when the explosive growth and worldwide proliferation of networks was not anticipated.

During the first decade of operation of the TCP/IP-based Internet, by the late 1980s, it became apparent that methods had to be developed to conserve address space. In the early 1990s, even after the introduction of classless network redesign, it became clear that this would not suffice to prevent IPv4 address exhaustion and that further changes to the Internet infrastructure were needed.^[3] By the beginning of 1992, several proposed systems were being circulated, and by the end of 1992, the IETF announced a call for white papers (RFC 1550) and the creation of the "IP Next Generation" (IPng) area of working groups.^[3][4]

The Internet Engineering Task Force adopted IPng on July 25, 1994, with the formation of several IPng working groups.^[3] By 1996, a series of RFCs were released defining Internet Protocol Version 6 (IPv6), starting with RFC 2460.

The technical discussion, development and introduction of IPv6 was not without controversy and the design has been criticized for lack of interoperability with IPv4 and other aspects, for example by noted computer scientist D. J. Bernstein.^[5]

Incidentally, the IPng architects could not use version number 5 as a successor to IPv4, because it had been assigned to an experimental flow-oriented streaming protocol (Internet Stream Protocol), similar to IPv4, intended to support video and audio.

It is widely expected that IPv4 will be supported alongside IPv6 for the foreseeable future. IPv4-only nodes are not able to communicate directly with IPv6 nodes, and will need assistance from an intermediary; see Transition mechanisms below.

[edit] IPv4 exhaustion

Estimates of the time frame until complete exhaustion of IPv4 addresses used to vary widely. In 2003, Paul Wilson (director of APNIC) stated that, based on then-current rates of deployment, the available space would last for one or two decades.^[6] In September 2005, a report by Cisco Systems suggested that the pool of available addresses would dry up in as little as 4 to 5 years.^[7] As of May 2009^[update], a daily updated report projected that the IANA pool of unallocated addresses would be exhausted in June 2011, with the various Regional Internet Registries using up their allocations from IANA in March 2012.^[8] There is now consensus among Regional Internet Registries that final milestones of the exhaustion process will be passed in 2010 or 2011 at the latest, and a policy process has started for the end-game and post-exhaustion era.^[9]

[edit] Features and differences from IPv4

In most regards, IPv6 is a conservative extension of IPv4. Most transport- and application-layer protocols need little or no change to operate over IPv6; exceptions are application protocols that embed network-layer addresses, such as FTP or NTPv3.

IPv6 specifies a new packet format, designed to minimize packet-header processing. Since the headers of IPv4 packets and IPv6 packets are significantly different, the two protocols are not interoperable.

[edit] Larger address space

The most important feature of IPv6 is a much larger address space than that of IPv4: addresses in IPv6 are 128 bits long, compared to 32-bit addresses in IPv4.

The very large IPv6 address space supports a total of 2¹²⁸ (about 3.4×10³⁸) addresses—or approximately 5×10²⁸ (roughly 2⁹⁵) addresses for each of the roughly 6.5 billion (6.5×10⁹) people alive in 2006.^[10] In a different perspective, this is 2⁵² (about 4.5×10¹⁵) addresses for every observable star in the known universe.^[11]

While these numbers are impressive, it was not the intent of the designers of the IPv6 address space to assure geographical saturation with usable addresses. Rather, the longer addresses allow a better, systematic, hierarchical allocation of addresses and efficient route aggregation. With IPv4, complex Classless Inter-Domain Routing (CIDR) techniques were developed to make the best use of the small address space. Renumbering an existing network for a new connectivity provider with different routing prefixes is a major effort with IPv4, as discussed in RFC 2071 and RFC 2072. With IPv6, however, changing the prefix announced by a few routers can in principle renumber an entire network since the host identifiers (the least-significant 64 bits of an address) can be independently self-configured by a host.

The size of a subnet in IPv6 is 2⁶⁴ addresses (64-bit subnet mask), the square of the size of the entire IPv4 Internet. Thus, actual address space utilization rates will likely be small in IPv6, but network management and routing will be more efficient because of the inherent design decisions of large subnet space and hierarchical route aggregation.

[edit] Stateless address autoconfiguration

IPv6 hosts can configure themselves automatically when connected to a routed IPv6 network using ICMPv6 router discovery messages. When first connected to a network, a host sends a link-local multicast router solicitation request for its configuration parameters; if configured suitably, routers respond to such a request with a router advertisement packet that contains network-layer configuration parameters.^[12]

If IPv6 stateless address autoconfiguration is unsuitable for an application, a network may use stateful configuration with the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) or hosts may be configured statically.

Routers present a special case of requirements for address configuration, as they often are sources for autoconfiguration information, such as router and prefix advertisements. Stateless configuration for routers can be achieved with a special router renumbering protocol specified in RFC 2894.^[13]

[edit] Multicast

Multicast, the ability to send a single packet to multiple destinations, is part of the base specification in IPv6. This is unlike IPv4, where it is optional (although usually implemented).

IPv6 does not implement broadcast, which is the ability to send a packet to all hosts on the attached link. The same effect can be achieved by sending a packet to the link-local all hosts multicast group. It therefore lacks the notion of a broadcast address—the highest address in a subnet (the broadcast address for that subnet in IPv4) is considered a normal address in IPv6.

Most environments, however, do not currently^[update] have their network infrastructures configured to route multicast packets; multicasting on single subnet will work, but global multicasting might not.

IPv6 multicast shares common features and protocols with IPv4 multicast, but also provides changes and improvements. When even the smallest IPv6 global routing prefix is assigned to an organization, the organization is also assigned the use of 4.2 billion globally routable source-specific IPv6 multicast groups to assign for inner-domain or cross-domain multicast applications [RFC 3306]. In IPv4 it was very difficult for an organization to get even one globally routable cross-domain multicast group assignment and implementation of cross-domain solutions was very arcane [RFC 2908]. IPv6 also supports new multicast solutions, including Embedded Rendezvous Point [RFC 3956] which simplifies the deployment of cross domain solutions.

[edit] Mandatory network layer security

Internet Protocol Security (IPsec), the protocol for IP encryption and authentication, forms an integral part of the base protocol suite in IPv6. IPsec support is mandatory in IPv6; this is unlike IPv4, where it is optional (but usually implemented). IPsec, however, is not widely used at present except for securing traffic between IPv6 Border Gateway Protocol routers.

[edit] Simplified processing by routers

A number of simplifications have been made to the packet header, and the process of packet forwarding has been simplified, in order to make packet processing by routers simpler and hence more efficient. Concretely,

• The packet header in IPv6 is simpler than that used in IPv4, with many rarely used fields moved to separate options; in effect, although the addresses in IPv6 are four times larger, the (option-less) IPv6 header is only twice the size of the (option-less) IPv4 header.

• IPv6 routers do not perform fragmentation. IPv6 hosts are required to either perform PMTU discovery, perform end-to-end fragmentation, or to send packets smaller than the IPv6 minimum MTU size of 1280 bytes.

• The IPv6 header is not protected by a checksum; integrity protection is assumed to be assured by both a link layer checksum and a higher layer (TCP, UDP, etc.) checksum. In effect, IPv6 routers do not need to recompute a checksum when header fields (such as the TTL or Hop Count) change. This improvement may have been made less necessary by the development of routers that perform checksum computation at link speed using dedicated hardware, but it is still relevant for software based routers.

• The Time-to-Live field of IPv4 has been renamed to Hop Limit, reflecting the fact that routers are no longer expected to compute the time a packet has spent in a queue.

[edit] Mobility

Unlike mobile IPv4, Mobile IPv6 (MIPv6) avoids triangular routing and is therefore as efficient as normal IPv6. IPv6 routers may also support Network Mobility (NEMO) [RFC 3963] which allows entire subnets to move to a new router connection point without renumbering. However, since neither MIPv6 nor MIPv4 or NEMO are widely deployed today, this advantage is mostly theoretical.

[edit] Options extensibility

IPv4 has a fixed size (40 bytes) of option parameters. In IPv6, options are implemented as additional extension headers after the IPv6 header, which limits their size only by the size of an entire packet. The extension header mechanism allows IPv6 to be easily 'extended' to support future services for QoS, security, mobility, etc. without a redesign of the basic protocol.

[edit] Jumbograms

IPv4 limits packets to 64 KiB of payload. IPv6 has optional support for packets over this limit, referred to as jumbograms, which can be as large as 4 GiB. The use of jumbograms may improve performance over high-MTU networks. The use of jumbograms is indicated by the Jumbo Payload Option header.

[edit] Packet format

The IPv6 packet is composed of three main parts: the fixed header, optional extension headers and the payload.

[edit] Fixed header

The fixed header makes up the first 40 octets (320 bits) of an IPv6 data packet. The format of the fixed header is presented in the table below. The octet (byte) offsets are in hexadecimal (base 16) and the bit offsets are in decimal (base 10).

Octet Offset		0								1								2								3
	Bit Offset	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
0	0	Version				Traffic Class								Flow Label
4	32	Payload Length																Next Header								Hop Limit
8	64	Source Address
C	96
10	128
14	160
18	192	Destination Address
1C	224
20	256
24	288

The fields used in the header are:

• Version: The number 6 encoded (bit sequence 0110).
• Traffic class: The packet priority (8 bits). Priority values subdivide into ranges: traffic where the source provides congestion control and non-congestion control traffic.
• Flow label: Used for QoS management (20 bits). Originally created for giving real-time applications special service, but currently unused.^[14]
• Payload length: The size of the payload in octets (16 bits). When cleared to zero, the option is a "Jumbo payload" (hop-by-hop).
• Next header: Specifies the next encapsulated protocol. The values are compatible with those specified for the IPv4 protocol field (8 bits).
• Hop limit: Replaces the time to live field of IPv4 (8 bits).
• Source and destination addresses: 128 bits each.

The protocol field of IPv4 is replaced with a next header field. This field usually specifies the transport layer protocol used by a packet's payload. In the presence of options, however, the next header field specifies the presence of one or more out of six extension headers, which then follow the IPv6 header in distinct order; the payload's protocol itself is specified in the next header field of the last extension header.

[edit] Extension header

Extension Header	Type	Size	Description	RFC
Hop-By-Hop Options	0	variable	Options that need to be examined by all devices on the path.	RFC 2460
Routing	43	variable	Methods to specify the route for a datagram. (Used with Mobile IPv6)	RFC 2460, RFC 3775, RFC 5095
Fragment	44	64 bits	Contains parameters for fragmentation of datagrams.	RFC 2460
Authentication Header (AH)	51	variable	Contains information used to verify the authenticity of most parts of the packet. (See IPsec)	RFC 4302
Encapsulating Security Payload (ESP)	50	variable	Carries encrypted data for secure communication. (See IPsec).	RFC 4303
Destination Options	60	variable	Options that need to be examined only by the destination of the packet.	RFC 2460
No Next Header	59	empty	A placeholder indicating no next header.	RFC 2460

[edit] Payload

The payload can have a size of up to 64 KB in standard mode, or larger with a "jumbo payload" option in a Hop-By-Hop Options extension header.

Fragmentation is handled only in the sending host in IPv6: routers never fragment a packet, and hosts are expected to use Path MTU discovery.

[edit] Addressing

The length of network addresses emphasize a most important change when moving from IPv4 to IPv6. IPv6 addresses are 128 bits long (as defined by RFC 4291), whereas IPv4 addresses are 32 bits; where the IPv4 address space contains roughly 4.3×10⁹ (4.3 billion) addresses, IPv6 has enough room for 3.4×10³⁸ (340 trillion trillion trillion) unique addresses.

IPv6 addresses are normally written with hexadecimal digits and colon separators like 2001:db8:85a3::8a2e:370:7334, as opposed to the dot-decimal notation of the 32 bit IPv4 addresses. IPv6 addresses are typically composed of two logical parts: a 64-bit (sub-)network prefix, and a 64-bit host part.

IPv6 addresses are classified into three types: unicast addresses which uniquely identify network interfaces, anycast addresses which identify a group of interfaces—mostly at different locations—for which traffic flows to the nearest one, and multicast addresses which are used to deliver one packet to many interfaces. Broadcast addresses are not used in IPv6. Each IPv6 address also has a 'scope', which specifies in which part of the network it is valid and unique. Some addresses have node scope or link scope; most addresses have global scope (i.e. they are unique globally).

Some IPv6 addresses are used for special purposes, like the loopback address. Also, some address ranges are considered special, like link-local addresses (for use in the local network only) and solicited-node multicast addresses (used in the Neighbor Discovery Protocol).

A quad-A record (AAAA) is defined in the DNS for returning IPv6 addresses to forward queries; a new format of PTR record is also defined for reverse queries.

[edit] Transition mechanisms

Until IPv6 completely supplants IPv4, a number of transition mechanisms^[15] are needed to enable IPv6-only hosts to reach IPv4 services and to allow isolated IPv6 hosts and networks to reach the IPv6 Internet over the IPv4 infrastructure.

For the period while IPv6 hosts and routers co-exist with IPv4 systems various proposals have been made:

• RFC 2893 (Transition Mechanisms for IPv6 Hosts and Routers), obsoleted by RFC 4213 (Basic Transition Mechanisms for IPv6 Hosts and Routers)
• RFC 2766 (Network Address Translation - Protocol Translation NAT-PT), obsoleted as explained in RFC 4966 (Reasons to Move the Network Address Translator - Protocol Translator NAT-PT to Historic Status)
• RFC 2185 (Routing Aspects of IPv6 Transition)
• RFC 3493 (Basic Socket Interface Extensions for IPv6)
• RFC 3056 (Connection of IPv6 Domains via IPv4 Clouds)
• RFC 4380 (Teredo: Tunneling IPv6 over UDP through Network Address Translations NATs)
• RFC 4214 (Intra-Site Automatic Tunnel Addressing Protocol ISATAP)
• RFC 3053 (IPv6 Tunnel Broker)
• RFC 3142 (An IPv6-to-IPv4 Transport Relay Translator)

[edit] Dual stack

Since IPv6 represents a conservative extension of IPv4, it is relatively easy to write a network stack that supports both IPv4 and IPv6 while sharing most of the code. Such an implementation is called a dual stack, and a host implementing a dual stack is called a dual-stack host. This approach is described in RFC 4213.

Most current implementations of IPv6 use a dual stack. Some early experimental implementations used independent IPv4 and IPv6 stacks.

[edit] IPv4-mapped addresses

Dual stack IPv6/IPv4 implementations typically support a special class of addresses, the IPv4-mapped addresses. This address type has its first 80 bits set to zero and the next 16 set to one while its last 32 bits represent an IPv4 address. These addresses are commonly represented with their last 32 bits written in the customary dot-decimal notation of IPv4; for example, ::ffff:192.0.2.128 is the IPv4-mapped IPv6 address for IPv4 address 192.0.2.128.

This address type allows the transparent use of the Transport Layer protocols over IPv4 through the IPv6 networking API. A beneficial feature of this mechanism is that server applications only need to open a single listening socket to handle connections from clients using IPv6 or IPv4 protocols. IPv6 clients will be handled natively by default, and IPv4 clients appear as IPv6 clients with an appropriately mapped address. It can also be used to establish IPv4 connections specifically with an IPv6 socket. While the network protocol on the transmission medium is IPv4, the connection is presented as an IPv6 interface to the application.

Because of the significant internal differences between IPv4 and IPv6 at all levels of the IP stack, some of the lower level functionality that may be exposed by the IPv6 stack might not work with IPv4 mapped addresses, if there is no direct translation to IPv4.

Some common IPv6 stacks do not support the IPv4 mapped address feature, either because the IPv6 and IPv4 stacks are separate implementations (Microsoft Windows prior to Vista/Longhorn: e.g. XP/2003), or because of security concerns (OpenBSD). On these operating systems, it is necessary to open a separate socket for each IP protocol that is to be supported. On some systems (e.g., Linux, NetBSD, FreeBSD) this feature is controlled by the socket option IPV6_V6ONLY as specified in RFC 3493.

[edit] Tunneling

In order to reach the IPv6 Internet, an isolated host or network must use the existing IPv4 infrastructure to carry IPv6 packets. This is done using a technique known as tunneling which consists of encapsulating IPv6 packets within IPv4, in effect using IPv4 as a link layer for IPv6.

The direct encapsulation of IPv6 datagrams within IPv4 packets is indicated by IP protocol number 41. IPv6 can also be encapsulated within UDP packets e.g. in order to cross a router or NAT device that blocks protocol 41 traffic. Other encapsulation schemes, such as used in AYIYA or GRE, are also popular.

[edit] Automatic tunneling

Automatic tunneling refers to a technique where the routing infrastructure automatically determines the tunnel endpoints. RFC 3056 recommends 6to4 tunneling for automatic tunneling, which uses protocol 41 encapsulation.^[16] Tunnel endpoints are determined by using a well-known IPv4 anycast address on the remote side, and embedding IPv4 address information within IPv6 addresses on the local side. 6to4 is widely deployed today.

Teredo is an automatic tunneling technique that uses UDP encapsulation and can allegedly cross multiple NAT boxes.^[17] IPv6, including 6to4 and Teredo tunneling, are enabled by default in Windows Vista.^[18] Most Unix systems only implement native support for 6to4, but Teredo can be provided by third-party software such as Miredo.

ISATAP^[19] treats the IPv4 network as a virtual IPv6 local link, with mappings from each IPv4 address to a link-local IPv6 address. Unlike 6to4 and Teredo, which are inter-site tunnelling mechanisms, ISATAP is an intra-site mechanism, meaning that it is designed to provide IPv6 connectivity between nodes within a single organisation.

[edit] Configured tunneling (6in4)

In configured tunneling, the tunnel endpoints are explicitly configured, either by an administrator manually or the operating system's configuration mechanisms, or by an automatic service known as a tunnel broker.^[20] Configured tunneling is usually more deterministic and easier to debug than automatic tunneling, and is therefore recommended for large, well-administered networks.

Raw encapsulation of IPv6 packets using IPv4 protocol number 41 is recommended for configured tunnelling; this is sometimes known as 6in4 tunnelling. As with automatic tunnelling, encapsulation within UDP may be used in order to cross NAT boxes and firewalls.

[edit] Proxying and translation for IPv6-only hosts

After the Regional Internet Registries have exhausted their pools of available IPv4 addresses, it is likely that hosts newly added to the Internet might only have IPv6 connectivity. For these clients to have backward-compatible connectivity to existing IPv4-only resources, suitable translation mechanisms must be deployed.

One form of translation is the use of a dual-stack application-layer proxy; for example a web proxy.

NAT-like techniques for application-agnostic translation at the lower layers have also been proposed. Most have been found to be too unreliable in practice because of the wide range of functionality required by common application-layer protocols, and are considered by many to be obsolete.

[edit] IPv6 readiness

[edit] Adoption issues

Issues of IPv6 adoption include:

• legacy equipment where
  • the manufacturer no longer exists to provide support
  • the manufacturer refuses to produce updates to support IPv6 or provides them but only at a prohibitive cost.
  • software upgrades are impossible (for example: software in permanent ROM)
  • the device has insufficient resources to implement the IPv6 stack (usually a lack of ROM or RAM)
  • the device can handle IPv6 but only at a much lower performance than IPv4 (an issue with many older routers)
• manufacturers providing new equipment with sufficient resources for IPv6
• manufacturers investing in developing new software for IPv6 support
• publicity to persuade end-users to prepare to upgrade existing equipment
• publicity to educate or inform end-users about IPv4 obsolescence to create demand for IPv6-capable equipment
• ISPs not investing technical resources into preparing for IPv6

There are two distinct classes of users of networking equipment, informed (mainly commercial and professional), and uninformed (mainly consumer). The former understand that network devices are specialist computers which may need software upgrades for security and performance fixes. The latter generally treat their networking equipment as appliances, which are configured only when first unboxed, if at all, and only ever undergo firmware upgrades when absolutely necessary. Inevitably it is the latter group who have no knowledge of IPv4 or v6, but who are most likely to suffer when their equipment has to be replaced, since commercial grade equipment has generally handled IPv6 for quite a few years.

Most equipment such as hosts and routers require explicit IPv6 support. Fewer problems arise with equipment which only does low-level transport, such as cables, most ethernet adapters, and most layer-2 switches.

As of 2007, IPv6 readiness is currently not considered in most consumer purchasing decisions. If such equipment is not IPv6-capable, it might need to be upgraded or replaced prematurely if connectivity from or to new users and to servers using IPv6 addresses is required.

As with the year-2000 compatibility, IPv6 compatibility is mainly a software/firmware issue. However, unlike the year-2000 issue, there seems to be virtually no effort to ensure compatibility of older equipment and software by manufacturers. Furthermore, even compatibility of products now available is unlikely for many types of software and equipment. This is caused by only a recent realisation that IPv4 exhaustion is imminent, and the hope that we will be able to get by for a relatively long time with a combined IPv4/IPv6 situation. There is a tug-of-war going on in the internet community whether the transition will/should be rapid or long. Specifically, an important question is whether almost all internet servers should be ready to serve to new IPv6-only clients by 2012. Universal access to IPv6-only servers will be even more of a challenge.

Most equipment would be fully IPv6 capable with a software/firmware update if the device has sufficient code and data space to support the additional protocol stack. However, as with 64-bit Windows and Wi-Fi Protected Access support, manufacturers are likely to try to save on development costs for hardware which they no longer sell, and to try to get more sales from new "IPv6-ready" equipment. Even when chipset makers develop new drivers for their chipsets, device manufacturers might not pass these on to the consumers. Moreover, as IPv6 gets implemented, optional features might become important, such as IPv6 mobile.

Home routers are usually not IPv6 ready.^{[citation needed]} As for the CableLabs consortium, the 160 Mbit/s DOCSIS 3.0 IPv6-ready specification for cable modems has only been issued in August 2006. IPv6 capable Docsis 2.0b was skipped while the widely used DOCSIS 2.0 does not support IPv6. The new 'DOCSIS 2.0 + IPv6' standard also supports IPv6, which may on the cable modem side only require a firmware upgrade.^[21][22] It is expected that only 60% of cable modems' servers and 40% of cable modems will be DOCSIS 3.0 by 2011.^[23] Other equipment which is typically not IPv6-ready range from Skype and SIP phones to oscilloscopes and printers. Professional network routers in use should be IPv6-ready. Most personal computers should also be IPv6-ready, because the network stack resides in the operating system. Most applications with network capabilities are not ready, but could be upgraded with support from the developers. Since February 2002, with J2SE 1.4, all applications that are 100% Java have implicit support for IPv6 addresses.^[24]

ADSL services offer a problem if the access networks of the incumbent telephone connection cannot support IPv6, such that independent ADSL providers cannot provide native IPv6 connectivity.

[edit] IPv6 conformance testing and evaluation

A few organizations are involved, locally and internationally, with IPv6 testing and evaluation ranging from the United States Department of Defense to the University of New Hampshire. Fuzzing, Fault injection and mutation test equipment and software is available from companies such as Mu Dynamics, Ixia and Codenomicon^[25]; which all also provide capability for creating and customizing your own IPv6 tests. Other classes of test equipment, including load and performance and conformance are available from companies like Spirent, Ixia and Agilent Technologies.

[edit] Deployment

Although IPv4 address exhaustion has been slowed by the introduction of classless inter-domain routing (CIDR) and the extensive use of network address translation (NAT), address uptake has accelerated again in recent years.^{[citation needed]} Some forecasts expect complete depletion by the year 2012.^[8]

As of 2008, IPv6 accounts for a minuscule fraction of the used addresses and the traffic in the publicly-accessible Internet which is still dominated by IPv4.^[26]

The 2008 Summer Olympic Games were a notable event in terms of IPv6 deployment, being the first time a major world event has had a presence on the IPv6 Internet at http://ipv6.beijing2008.cn/en (IP addresses 2001:252:0:1::2008:6 and 2001:252:0:1::2008:8) and all network operations of the Games were conducted using IPv6.^[27] It is believed that the Olympics provided the largest showcase of IPv6 technology since the inception of IPv6.^[28]

Cellular telephone systems present a large deployment field for Internet Protocol devices as mobile telephone service is being transitioned from 3G systems to next generation (4G) technologies in which voice is provisioned as a Voice over Internet Protocol (VoIP) service. This mandates the use of IPv6 for such networks due to the impending IPv4 address exhaustion. In the U.S., cellular operator Verizon has released technical specifications for devices operating on its future networks.^[29] The specification mandates IPv6 operation according to the 3GPP Release 8 Specifications (March 2009) and deprecates IPv4 as an optional capability.

Some implementations of the BitTorrent peer-to-peer file transfer protocol make extensive use of IPv6 to avoid NAT issues^[30].

[edit] Major announcements and availability

Year	Announcements and availability
1996	Alpha quality IPv6 support in Linux kernel development version 2.1.8.[31]
	6bone (an IPv6 virtual network for testing) was started.
1997	By the end of 1997, a large number of interoperable IPv6 implementations exist.[32][33]
	By the end of 1997 IBM's AIX 4.3 is the first commercial platform supporting IPv6.[34][35]
	Also in 1997, Early Adopter Kits for DEC's operating systems, Tru64 and OpenVMS, were available.[36]
1998	Microsoft Research[37] releases its first experimental IPv6 stack. This support is not intended for use in a production environment.
2000	Production-quality BSD support for IPv6 becomes generally available in early to mid-2000 in FreeBSD, OpenBSD, and NetBSD via the KAME project.[38]
	Microsoft releases an IPv6 technology preview version for Windows 2000 in March 2000.[37]
	Sun Solaris supports IPv6 in Solaris 8 in February.[39]
	Compaq ships IPv6 with Tru64.[36]
2001	In January, Compaq ships IPv6 with OpenVMS.[36]
	Cisco Systems introduces IPv6 support on Cisco IOS routers and L3 switches.[40]
	HP introduces IPv6 with HP-UX 11i v1.[41]
2002	Microsoft Windows NT 4.0 and Windows 2000 SP1 have limited IPv6 support for research and testing since at least 2002.
	Microsoft Windows XP (2001) supports IPv6 for developmental purposes. In Windows XP SP1 (2002) and Windows Server 2003, IPv6 is included as a core networking technology, suitable for commercial deployment.[42]
	IBM z/OS supports IPv6 since version 1.4 (generally availability in September 2002).[43]
2003	Apple Mac OS X v10.3 "Panther" (2003) supports IPv6 which is enabled by default.[44]
	In July, ICANN announces that IPv6 address records for the Japan (jp) and Korea (kr) country code top-level domain nameservers are visible in the DNS root server zone files with serial number 2004072000. The IPv6 records for France (fr) are added a later. This makes IPv6 publicly operational.
2005	Linux 2.6.12 removes experimental status from its IPv6 implementation.[45]
2007	Microsoft Windows Vista (2007) supports IPv6 which is enabled by default.[42]
	Apple's AirPort Extreme 802.11n base station includes an IPv6 gateway in its default configuration. It uses 6to4 tunneling and manually configured static tunnels.[46]
2008	On February 4, 2008, IANA adds AAAA records for the IPv6 addresses of six root name servers.[47][48] With this transition, it is now possible for two Internet hosts to fully communicate without using IPv4.
	On March 12, 2008, Google launches a public IPv6 web interface to its popular search engine at the URL http://ipv6.google.com.[49]
	On December 11, 2008, Hurricane Electric became the first network in the world to connect over 300 IPv6 networks.[50]
2009	In January 2009, Google extended its IPv6 initiative with Google over IPv6, which offers IPv6 support for Google services to compatible networks.

[edit] IPv6 network address translation

Network address translation, a widely spread method to delay IPv4 address space exhaustion, was not considered for implementation in the IPv6 core definitions. However, due to its popularity, proponents desire re-implementation in IPv6 for other reasons. The Internet Architecture Board has engaged in the ongoing debate.^[51]

[edit] See also

• IPv4 address exhaustion
• IPv6 deployment
• Comparison of IPv6 application support
• China Next Generation Internet
• List of IPv6 tunnel brokers
• Miredo
• ICMPv6
• University of New Hampshire InterOperability Laboratory involvement in the IPv6 Ready Logo Program
• The US DoD Joint Interoperability Test Command DoD IPv6 Product Certification Program
• SATSIX

[edit] References

[edit] External links

• IPv6 Backbone Network Topology
• RFC 4942 - IPv6 Transition/Coexistence Security Considerations
• draft-itojun-v6ops-v4mapped-harmful
• IPv6.com Information Portal
• IPv6ActNow.org The IPv6 information website from the RIPE NCC