Internet Protocol version 6
) 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 .It is an Internet Layer
. 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
(IETF) with the publication of an Internet standard
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
) addresses. This expansion provides flexibility
in allocating addresses and routing traffic and eliminates the
primary need for network
(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
information (MAC address
is integrated into
the design of the IPv6 architecture. Internet
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
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 by Google Inc.
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
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
redesign, it became clear that this would not suffice
to prevent IPv4 address
and that further changes to the Internet
infrastructure were needed. 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
The Internet Engineering Task Force adopted IPng on July 25, 1994,
with the formation of several IPng working groups. By 1996, a
series of RFCs
defining Internet Protocol Version 6 (IPv6), starting with RFC
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.
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
), similar to IPv4, intended to support video and
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
Estimates of the time frame until complete exhaustion of IPv4
addresses used to vary widely. In 2003, Paul Wilson (director of
) stated that, based on then-current
rates of deployment, the available space would last for one or two
decades. 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. , a
daily updated report projected that the IANA
pool of unallocated
addresses would be exhausted in June 2011, with the various
using up their allocations from IANA in March 2012.
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.
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
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
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
for each of the roughly 6.5 billion (6.5×109
alive in 2006. In a different perspective, this is 252
) addresses for every observable star in
the known universe.
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
(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
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
Stateless address autoconfiguration
IPv6 hosts can configure themselves automatically when connected to
a routed IPv6 network using ICMPv6
discovery messages. When first connected to a network, a host sends
a link-local multicast router solicitation
its configuration parameters; if configured suitably, routers
respond to such a request with a router advertisement
packet that contains network-layer configuration parameters.
If IPv6 stateless address autoconfiguration is unsuitable for an
application, a network may use stateful configuration with the
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.
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
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 have their network
infrastructures configured to route multicast packets; multicasting
on single subnet will work, but global multicasting might
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.
Mandatory network layer security
Internet Protocol Security
, 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
, however, is not widely
used at present except for securing traffic between IPv6 Border Gateway Protocol
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
- 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.
Unlike mobile IPv4, Mobile IPv6
avoids triangular routing
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.
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.
IPv4 limits packets to 64 KiB
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.
The IPv6 packet is composed of three main parts: the fixed header,
optional extension headers and the payload.
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
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
- 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.
field of IPv4 is replaced with a next
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
||Options that need to be examined by all devices on the
||Methods to specify the route for a datagram. (Used with
||RFC 2460, RFC 3775, RFC 5095
||Contains parameters for fragmentation of datagrams.
|Authentication Header (AH)
||Contains information used to verify the authenticity of most
parts of the packet. (See IPsec)
|Encapsulating Security Payload (ESP)
||Carries encrypted data for secure communication. (See IPsec).
||Options that need to be examined only by the destination of the
|No Next Header
||A placeholder indicating no next header.
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
handled only in the sending host in IPv6: routers never fragment a
packet, and hosts are expected to use Path MTU discovery
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
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
, as opposed to the
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
IPv6 addresses are classified into three types: unicast
addresses which uniquely identify network
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
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
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
Until IPv6 completely supplants IPv4, a number of transition
mechanisms 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
- 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
- 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
- RFC 3053 (IPv6 Tunnel Broker)
- RFC 3142 (An IPv6-to-IPv4 Transport Relay Translator)
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
Most current implementations of IPv6 use a dual stack. Some early
experimental implementations used independent IPv4 and IPv6
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
These addresses are commonly represented with their last 32 bits
written in the customary dot-decimal notation
of IPv4; for
is the IPv4-mapped IPv6
address for IPv4 address
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
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 connection
an IPv6 socket. While the network protocol on the transmission
medium is IPv4, the connection is presented as an IPv6 interface to
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
). 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
) this feature is controlled by the socket
as specified in RFC 3493.
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
, are also popular.
refers to a technique where the
routing infrastructure automatically determines the tunnel
endpoints. RFC 3056 recommends 6to4
for automatic tunneling, which uses protocol 41 encapsulation.
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
is an automatic
tunneling technique that uses UDP encapsulation and can allegedly
cross multiple NAT boxes. IPv6, including 6to4 and Teredo
tunneling, are enabled by default in Windows Vista
. Most Unix systems only
implement native support for 6to4, but Teredo can be provided by
third-party software such as Miredo
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
tunnelling mechanisms, ISATAP is an
mechanism, meaning that it is designed to
provide IPv6 connectivity between nodes within a single
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
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
Proxying and translation for IPv6-only hosts
After the Regional Internet
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,
must be deployed.
One form of translation is the use of a dual-stack application-layer proxy
; for example a web
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.
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
- 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
- manufacturers investing in developing new software for IPv6
- publicity to persuade end-users to prepare to upgrade existing
- 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
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
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
Home routers are usually not IPv6 ready. 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. It is expected that only 60% of cable
modems' servers and 40% of cable modems will be DOCSIS 3.0 by 2011.
Other equipment which is typically not IPv6-ready range from
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
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
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
equipment and software is available from companies such as Mu Dynamics
; 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
and Agilent Technologies
Although IPv4 address
has been slowed by the introduction of classless inter-domain
(CIDR) and the extensive use of network address translation
(NAT), address uptake has accelerated again in recent years. Some
forecasts expect complete depletion by the year 2012.
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.
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. It is
believed that the Olympics provided the largest showcase of IPv6
technology since the inception of IPv6.
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
) technologies in which voice is provisioned
as a Voice over Internet
(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
technical specifications for devices operating on its future
networks. The specification mandates IPv6 operation according to
the 3GPP Release 8 Specifications (March 2009)
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.
Major announcements and availability
||Announcements and availability
||Alpha quality IPv6 support in
Linux kernel development version
|6bone (an IPv6 virtual network for
testing) was started.
||By the end of 1997, a large number of interoperable IPv6
|By the end of 1997 IBM's AIX 4.3 is the first commercial
platform supporting IPv6.
|Also in 1997, Early Adopter Kits for DEC's operating systems,
Tru64 and OpenVMS, were
||Microsoft Research releases
its first experimental IPv6 stack. This support is not intended for
use in a production environment.
||Production-quality BSD support for IPv6 becomes generally
available in early to mid-2000 in FreeBSD,
OpenBSD, and NetBSD
via the KAME project.
|Microsoft releases an IPv6 technology preview version for
Windows 2000 in March 2000.
|Sun Solaris supports IPv6 in Solaris 8
|Compaq ships IPv6 with Tru64.
||In January, Compaq ships IPv6 with
|Cisco Systems introduces IPv6
support on Cisco IOS routers and L3
|HP introduces IPv6 with HP-UX 11i v1.
||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.
|IBM z/OS supports IPv6 since version 1.4
(generally availability in September 2002).
||Apple Mac OS X v10.3 "Panther" (2003) supports IPv6
which is enabled by default.
|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.
||Linux 2.6.12 removes experimental status
from its IPv6 implementation. Linux
||Microsoft Windows Vista (2007)
supports IPv6 which is enabled by default.
|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.
||On February 4, 2008, IANA adds AAAA records for the IPv6
addresses of six root name servers. With this transition, it is now
possible for two Internet hosts to fully communicate without using
|On March 12, 2008, Google launches a
public IPv6 web interface to its popular search engine at the URL
|On December 11, 2008, Hurricane
Electric became the first network in the world to connect over
300 IPv6 networks.
||In January 2009, Google extended its IPv6 initiative with
Google over IPv6, which offers IPv6 support for
Google services to
IPv6 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
engaged in the ongoing debate.