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IPv6 address Unicast and anycast address format
Unicast and anycast addresses are typically composed of two logical parts: a 64-bit network prefix used for routing, and a 64-bit interface identifier used to identify a host's network interface.

General unicast address format (routing prefix size varies)

field routing prefix subnet id interface identifier

The network prefix (the routing prefix combined with the subnet id) is contained in the most significant 64 bits of the address

A link-local address is also based on the interface identifier, but uses a different format for the network prefix.

The prefix field contains the binary value The 54 zeroes that follow make the total network prefix the same for all link-local addresses (fe80::/64 link-local address prefix), rendering them non-routable.

IPv6 address Address block sizes
The size of a block of addresses is specified by writing a slash (/) followed by a number in decimal whose value is the length of the network prefix in bits, rather than by explicitly specifying which addresses are in the block. For example, an address block with 48 bits in the prefix is indicated by /48. Such a block contains 2128 − 48 = 280 addresses. The smaller the value of the network prefix, the larger the block: a /21 block is 8 times larger than a /24 block.

IPv6 address Special allocation
To allow for provider changes without renumbering, provider-independent address space – assigned directly to the end user by the RIRs – is taken from the special range 2001:678::/29.

IPv6 address Special allocation
Internet Exchange Points (IXPs) are assigned special addresses from the range 2001:7f8::/29 for communication with their connected ISPs. Root name servers have been assigned addresses from the same range.

IPv6 address Unspecified address
The address with all zero bits is called the unspecified address (corresponding to /32 in IPv4).

This address must never be assigned to an interface and is to be used only in software before the application has learned its host's source address appropriate for a pending connection. Routers must not forward packets with the unspecified address.

Applications may be listening on one or more specific interfaces for incoming connections, which are shown in listings of active internet connections by a specific IP address (and a port number, separated by a colon). When the unspecified address is shown it means that an application is listening for incoming connections on all available interfaces.

IPv6 address Default route
::/0 — The default unicast route address (corresponding to /0 in IPv4).

IPv6 address Unique local addresses

IPv6 address Unique local addresses
fc00::/7 — Unique local addresses (ULAs) are intended for local communication

IPv6 address Deprecated and obsolete addresses
Further information: Historical notes

IPv6 address Solicited-node multicast address
The least significant 24 bits of the solicited-node multicast address group ID are filled with the least significant 24 bits of the interface's unicast or anycast address. These addresses allow link-layer address resolution via Neighbor Discovery Protocol (NDP) on the link without disturbing all nodes on the local network. A host is required to join a Solicited-Node multicast group for each of its configured unicast or anycast addresses.

IPv6 packet Hop-by-hop options and destination options
The Hop-by-Hop Options extension header needs to be examined by all nodes on the packet's path, including sending and receiving nodes. The Destination Options extension header need to be examined by the destination node(s) only. The extension headers are both at least 8 octets in size; if more options are present than will fit in that space, blocks of 8 octets are added to the header repeatedly—containing options and padding—until all options are represented.

Length of this header in 8-octet units, not including the first 8 octets.

Contains one or more options, and optional padding fields to align options and to make the total header length a multiple of 8 octets. Options are TLV-coded.

IPv6 packet Routing The Routing extension header is used to direct a packet to one or more intermediate nodes before being sent to its destination. The header is at least 8 octets in size; if more Type-specific Data is needed than will fit in 4 octets, blocks of 8 octets are added to the header repeatedly, until all Type-specific Data is placed.

0 0 Next Header Hdr Ext Len Routing Type Segments Left
IPv6 packet Routing 0 0 Next Header Hdr Ext Len Routing Type Segments Left

IPv6 packet Routing The length of this header, in multiples of 8 octets, not including the first 8 octets.

IPv6 packet Routing Number of nodes this packet still has to visit before reaching its final destination.

Data that belongs to this type of routing header.
IPv6 packet Routing Data that belongs to this type of routing header.

IPv6 packet Fragment In order to send a packet that is larger than the path MTU, the sending node splits the packet into fragments. The Fragment extension header carries the information necessary to reassemble the original (unfragmented) packet.

IPv6 packet Fragment Offset, in 8-octet units, relative to the start of the fragmentable part of the original packet.

IPv6 packet Fragment Packet identification value, generated by the source node. Needed for reassembly of the original packet.

IPv6 packet Fragmenting
A packet containing a fragment of an original (larger) packet consists of two parts: the unfragmentable part of the original packet (which is the same for all fragments), and a piece of the fragmentable part of the original packet, identified by a fragment offset.

The unfragmentable part of a packet consists of the fixed header and some of the extension headers of the original packet (if present): all extension headers up to and including the Routing extension header, or else the Hop-by-Hop extension header. If neither extension headers are present, the unfragmentable part is just the fixed header.

The Next Header value of the last (extension) header of the unfragmentable part is set to 44 to indicate that a Fragment extension header follows. After the Fragment extension header a fragment of the rest of the original packet follows.

The first fragment(s) hold the rest of the extension headers (if present). After that the rest of the payload follows. Each fragment is a multiple of 8 octets in length, except the last fragment.

IPv6 packet Reassembly The original packet is reassembled by the receiving node by collecting all fragments and placing each fragment at the right offset and discarding the Fragment extension headers of the packets that carried them. Packets containing fragments need not arrive in sequence; they will be rearranged by the receiving node.

IPv6 packet Reassembly If not all fragments are received within 60 seconds after receiving the first packet with a fragment, reassembly of the original packet is abandoned and all fragments are discarded. If the first fragment was received (which contains the fixed header), a Time Exceeded message (ICMPv6 type 3, code 1) is returned to the node originating the fragmented packet, if the packet was discarded for this reason.

IPv6 packet Reassembly Receiving hosts must make a best-effort attempt to reassemble fragmented IP datagrams that, after reassembly, contain up to 1500 bytes

IPv6 IPv4 Internet Protocol Version 4 (IPv4) was the first publicly used version of the Internet Protocol

IPv6 IPv4 During the first decade of operation of the 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 redesign of the addressing system using a classless network model, it became clear that this would not suffice to prevent IPv4 address exhaustion, and that further changes to the Internet infrastructure were needed.

IPv6 IPv4 The last unassigned top-level address blocks of 16 million IPv4 addresses were allocated in February 2011 by the Internet Assigned Numbers Authority (IANA) to the five regional Internet registries (RIRs)

IPv6 subnetting reference CIDR Prefixes
|||| |||| |||| |||64 Single End-user LAN (default prefix size for SLAAC)

|||| |||| 36 possible future Local Internet registry extra-small allocations

|||| |||32 Local Internet registry minimum allocations

|||| ||28 Local Internet registry medium allocations

Subnetwork - IPv6 subnetting
The design of the IPv6 address space differs significantly from IPv4. The primary reason for subnetting in IPv4 is to improve efficiency in the utilization of the relatively small address space available, particularly to enterprises. No such limitations exist in IPv6, as the large address space available, even to end-users, is not a limiting factor.

An RFC 4291 compliant subnet always uses IPv6 addresses with 64 bits for the host portion

IPv6 does not implement special address formats for broadcast traffic or network numbers, and thus all addresses in a subnet are valid host addresses. The all-zeroes address is reserved as the Subnet-Router anycast address.

The recommended allocation for an IPv6 customer site is an address space with an 48-bit (/48) prefix. This provides subnets for a site. Despite this recommendation, other common allocations are /56 as well as /64 prefixes for a residential customer network.

Subnetting in IPv6 is based on the concepts of variable-length subnet masking (VLSM) and the Classless Inter-Domain Routing methodology. It is used to route traffic between the global allocation spaces and within customer networks between subnets and the Internet at large.

Network address translation - NAT loopback in IPv6
Network address translation will not be commonly used in IPv6, so NAT loopback will not be commonly needed

Note that both the client and server must support IPv6 and IPv4 addressing in the above scenario. Also note that 2001:db8::2 is the IPv6 IP address of the server (which was in the IPv4 example).

In the first example the packet was first sent to the default gateway since is not inside the same subnet as /16. Then the router, performing NAT loopback, forwards it to the configured device ( ).

In the second example the client detected that it was inside the same IPv6 subnet as the server, and sent the packet there directly.

Classless Inter-Domain Routing - IPv6 CIDR blocks
The standard subnet size for IPv6 networks is a /64 block, which is required for the operation of stateless address autoconfiguration

Comparison of IPv6 application support - Applications
Application Category IPv6 supported? Zone ID supported? Earliest version # with IPv6 support Notes Reference links

AbsoluteTelnet SSH client, Telnet client, SFTP Client Yes No 5.01 Supports SSH, Telnet, and SFTP

Apache httpd Web server Yes N/A "Virtual hosts on IPv6 addresses are broken in versions until "

Cerberus FTP Server FTP Server Yes N/A 3.0 Supports RFC 2428 FTP Extensions for IPv6

cURL File transfer software Yes

IIS Web server Yes N/A 6.0 Versions before 7.0 do not support bandwidth throttling, client IP address restrictions, FTP, or NNTP.

Internet Explorer Web browser Yes No 4.01 Versions before 7.0 may not be able to handle numerical addresses. Macintosh versions do not support IPv6.

Java Programming language Yes Yes Support on Windows XP/2003 was added in Java 1.5.0

Linux CIFS VFS SMB/CIFS client Yes cifs vfs version 1.48 is part of kernel

Linux NetKit ftp Console application Yes Yes 0.17? Standard Linux FTP client.

Linux NetKit Telnet Console application Yes Yes 0.17? Standard Linux telnet client and server.

Microsoft DNS DNS server Yes N/A 5.0 (2000) Windows 2000 DNS can handle AAAA records, but the Operating System does not ship with IPv6.

Microsoft Outlook client Yes 2003?

Mozilla / SeaMonkey Web browser Yes IPv6 is not preferred by default on Mac OS X.

Mozilla Firefox Web browser Yes Yes 1.5 IPv6 is not preferred by default on Mac OS X in Firefox 1.5 or 2.0, only in 3.0. Firefox is not able to connect to a SOCKS-Proxy with IPv6 and does not support PAC-Scripts what return IPv6.

Mozilla Thunderbird client Yes Version 2.0 & later appears to work with Mac OS X Version

MPlayer Multimedia player Yes N/A For example in HTTP streaming.

MySQL Database Yes Disabled by default before

Nmap Console application Yes Yes 3.10ALPHA1 Zone ID support since version 4.65

OpenTTD Game/simulation Yes

OpenVPN VPN client Yes 2.3 Partial support starting with version 2.0.

Opera Web browser Yes No 7.20b IPv6 support on Macintosh was added in Opera 9.0

Outlook Express client No N/A Windows Mail on the Windows Vista platform has IPv6 support.

Pidgin Instant messenger Yes 2.0 (GAIM had support in older builds) IPv6 is enabled on Linux builds, but not on Win32 builds.

Polipo Proxy server Yes No 0.8 Can be used for proxying between IPv4 and IPv6

PuTTY SSH client Yes Yes 0.58 Fully functional (also Zone ID's) from 0.59

Quagga Routing software Yes N/A OSPFv3 area support is incomplete.

rsync differential file synchronizer Yes native IPv6 support since 2.5.0, but hosts allow/deny in rsync.conf didn't work until

Squid cache Proxy server Yes 3.1

TightVNC VNC Optional Protocol version 3.5 Experimental IPv6 builds were made available in 2004.

tinc VPN client Yes 1.0 Defaults to IPv6; can be set to IPv4-only.

UDP Speed Test 3 Network Speed Test Tool Yes Yes 3.05 Unicast, Broadcast, Multicast, Anycast.

UploadFTP FTP, FTPS and SFTP Client Yes 2.0

VMware vSphere Client Systems management client Yes Performance reports do not support IPv6, but everything else appears to. This was tested using IPv6>IPv4 PT, where the server is on the IPv4 side.

Wget File transfer software Yes 1.9? May default to IPv4 transfers: "-6" option used to override.

Windows Media Player Multimedia player Yes 9.0?

Windows File and print sharing SMB/CIFS client/server Yes 5.2 (Server 2003) Windows XP 32-bit does not support IPv6 at the SMB/CIFS layer. The protocol is available for other applications ("ipv6 install" pre-SP1; protocol install afterwards).

xinetd Networking daemon Yes Version or newer recommended to avoid security issues.

Cisco AnyConnect VPN Client Yes Yes 2.0 No split tunneling allowed in IPv6. ASA 8.4 software required for full IPv6 mode.

Jump up ^ "0.1.3 Changelog". Retrieved March 03, 2011.

IPv6 Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion.

IPv6 IPv6 is intended to replace IPv4, which still carries the vast majority of Internet traffic as of As of September 2013, the percentage of users reaching Google services over IPv6 surpassed 2% for the first time.

IPv6 The two protocols are not designed to be interoperable, complicating the transition to IPv6.

IPv6 IPv6 addresses are represented as eight groups of four hexadecimal digits separated by colons, for example 2001:0db8:85a3:0042:1000:8a2e:0370:7334, but methods of abbreviation of this full notation exist.

IPv6 - Technical overview
Network security was a design requirement of the IPv6 architecture, and included the original specification of IPsec.

IPv6 - Technical overview
IPv6 does not specify interoperability features with IPv4, but essentially creates a parallel, independent network. Exchanging traffic between the two networks requires translator gateways or other transition technologies, such as the tunneling protocols 6to4, 6in4, and Teredo.

IPv6 - Working-group proposals
By the beginning of 1992, several proposals appeared for an expanded Internet addressing system and by the end of 1992 the IETF announced a call for white papers

The Internet Engineering Task Force adopted the IPng model on 25 July 1994, with the formation of several IPng working groups. By 1996, a series of RFCs was released defining Internet Protocol version 6 (IPv6), starting with RFC (Version 5 was used by the experimental Internet Stream Protocol.)

It is widely expected that the Internet will use IPv4 alongside IPv6 for the foreseeable future. IPv4-only and IPv6-only nodes cannot communicate directly, and need assistance from an intermediary gateway or must use other transition mechanisms.

IPv6 - Comparison with IPv4
Most transport and application-layer protocols need little or no change to operate over IPv6; exceptions are application protocols that embed internet-layer addresses, such as FTP and NTPv3, where the new address format may cause conflicts with existing protocol syntax.

IPv6 - Larger address space
Thus, actual address space utilization rates will be small in IPv6, but network management and routing efficiency is improved by the large subnet space and hierarchical route aggregation.

IPv6 - Larger address space
Renumbering an existing network for a new connectivity provider with different routing prefixes is a major effort with IPv4. 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.

IPv6 - Multicasting IPv6 also provides for new multicast implementations, including embedding rendezvous point addresses in an IPv6 multicast group address, which simplifies the deployment of inter-domain solutions.

IPv6 - Multicasting Thus each user of an IPv6 subnet automatically has available a set of globally routable source-specific multicast groups for multicast applications.

IPv6 - Stateless address autoconfiguration (SLAAC)
IPv6 hosts can configure themselves automatically when connected to an IPv6 network using the Neighbor Discovery Protocol via Internet Control Message Protocol version 6 (ICMPv6) router discovery messages. When first connected to a network, a host sends a link-local router solicitation multicast request for its configuration parameters; routers respond to such a request with a router advertisement packet that contains Internet Layer configuration parameters.

If IPv6 stateless address autoconfiguration is unsuitable for an application, a network may use stateful configuration with the Dynamic Host Configuration Protocol version 6 (DHCPv6) or hosts may be configured manually using static methods.

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

IPv6 - Network-layer security
Internet Protocol Security (IPsec) was originally developed for IPv6, but found widespread deployment first in IPv4, for which it was re-engineered. IPsec was a mandatory specification of the base IPv6 protocol suite, but has since been made optional.

IPv6 - Simplified processing by routers
In IPv6, the packet header and the process of packet forwarding have been simplified. Although IPv6 packet headers are at least twice the size of IPv4 packet headers, packet processing by routers is generally more efficient, thereby extending the end-to-end principle of Internet design. Specifically:

The packet header in IPv6 is simpler than that used in IPv4, with many rarely used fields moved to separate optional header extensions.

IPv6 routers do not perform fragmentation. IPv6 hosts are required to either perform path MTU discovery, perform end-to-end fragmentation, or to send packets no larger than the IPv6 default MTU size of 1280 octets.

Therefore, IPv6 routers do not need to recompute a checksum when header fields (such as the time to live (TTL) or hop count) change

The TTL field of IPv4 has been renamed to Hop Limit in IPv6, reflecting the fact that routers are no longer expected to compute the time a packet has spent in a queue.

IPv6 - Mobility Unlike mobile IPv4, mobile IPv6 avoids triangular routing and is therefore as efficient as native IPv6. IPv6 routers may also allow entire subnets to move to a new router connection point without renumbering.

IPv6 - Options extensibility
The IPv6 packet header has a fixed size (40 octets). 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 makes the protocol extensible in that it allows future services for quality of service, security, mobility, and others to be added without redesign of the basic protocol.

IPv6 - Jumbograms IPv4 limits packets to (216−1) octets of payload. An IPv6 node can optionally handle packets over this limit, referred to as jumbograms, which can be as large as (232−1) octets. The use of jumbograms may improve performance over high-MTU links. The use of jumbograms is indicated by the Jumbo Payload Option header.

IPv6 - Privacy Like IPv4, IPv6 supports globally unique IP addresses by which the network activity of each device can potentially be tracked.

IPv6 - Privacy The design of IPv6 intended to re-emphasize the end-to-end principle of network design that was originally conceived during the establishment of the early Internet. In this approach each device on the network has a unique address globally reachable directly from any other location on the Internet.

IPv6 - Privacy Network prefix tracking is less of a concern if the user's ISP assigns a dynamic network prefix via DHCP. Privacy extensions do little to protect the user from tracking if only one or two devices are using a static network prefix. In this scenario, the network prefix is the unique identifier for tracking.

IPv6 - Privacy In IPv4 the effort to conserve address space with network address translation (NAT) obfuscates network address spaces, hosts, and topologies. In IPv6 when using address auto-configuration, the Interface Identifier (MAC address) of an interface port is used to make its public IP address unique, exposing the type of hardware used and providing a unique handle for a user's online activity.

IPv6 - Privacy Privacy extensions for IPv6 have been defined to address these privacy concerns, although Silvia Hagen describes these as being largely due to 'misunderstanding'

IPv6 - Privacy Privacy extensions are enabled by default in Windows, OS X (since 10.7), and iOS (since version 4.3). Some Linux distributions have enabled privacy extensions as well.

IPv6 - Privacy Privacy extensions do not protect the user from other forms of activity tracking, such as tracking cookies.

IPv6 - Packet format The header consists of a fixed portion with minimal functionality required for all packets and may be followed by optional extensions to implement special features.

IPv6 - Packet format The fixed header occupies the first 40 octets (320 bits) of the IPv6 packet

IPv6 - Packet format Extension headers carry options that are used for special treatment of a packet in the network, e.g., for routing, fragmentation, and for security using the IPsec framework.

IPv6 - Packet format Without special options, a payload must be less than 64KB. With a Jumbo Payload option (in a Hop-By-Hop Options extension header), the payload must be less than 4 GB.

IPv6 - Packet format Unlike in IPv4, routers never fragment a packet. Hosts are expected to use Path MTU Discovery to make their packets small enough to reach the destination without needing to be fragmented. See IPv6 packet fragmentation.

IPv6 - Addressing Compared to IPv4, the most obvious advantage of IPv6 is its larger address space. IPv4 addresses are 32 bits long and number about 4.3×109 (4.3 billion). IPv6 addresses are 128 bits long and number about 3.4×1038 (340 undecillion). IPv6's addresses are deemed enough for the foreseeable future.

IPv6 - Addressing IPv6 addresses are written in eight groups of four hexadecimal digits separated by colons, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334. IPv6 unicast addresses other than those that start with binary 000 are logically divided into two parts: a 64-bit (sub-)network prefix, and a 64-bit interface identifier.

IPv6 - Addressing For stateless address autoconfiguration (SLAAC) to work, subnets require a /64 address block, as defined in RFC 4291 section 2.5.1

IPv6 - Addressing Each IPv6 address has a scope, which specifies in which part of the network it is valid and unique

IPv6 - Addressing Some IPv6 addresses are reserved for special purposes, such as loopback, 6to4 tunneling, and Teredo tunneling, as outlined in RFC Also, some address ranges are considered special, such as link-local addresses for use on the local link only, Unique Local addresses (ULA), as described in RFC 4193, and solicited-node multicast addresses used in the Neighbor Discovery Protocol.

IPv6 - IPv6 in the Domain Name System
In the Domain Name System, hostnames are mapped to IPv6 addresses by AAAA resource records, so-called quad-A records. For reverse resolution, the IETF reserved the domain ip6.arpa, where the name space is hierarchically divided by the 1-digit hexadecimal representation of nibble units (4 bits) of the IPv6 address. This scheme is defined in RFC 3596.

IPv6 - Address representation
The 128 bits of an IPv6 address are represented in 8 groups of 16 bits each. Each group is written as 4 hexadecimal digits and the groups are separated by colons (:). The address 2001:0db8:0000:0000:0000:ff00:0042:8329 is an example of this representation.

For convenience, an IPv6 address may be abbreviated to shorter notations by application of the following rules, where possible.

One or more leading zeroes from any groups of hexadecimal digits are removed; this is usually done to either all or none of the leading zeroes. For example, the group 0042 is converted to 42.

Consecutive sections of zeroes are replaced with a double colon (::). The double colon may only be used once in an address, as multiple use would render the address indeterminate. RFC 5952 recommends that a double colon must not be used to denote an omitted single section of zeroes.

An example of application of these rules:

After omitting consecutive sections of zeroes: 2001:db8::ff00:42:8329

The loopback address, 0000:0000:0000:0000:0000:0000:0000:0001, may be abbreviated to ::1 by using both rules.

As an IPv6 address may have more than one representation, the IETF has issued a proposed standard for representing them in text.

IPv6 - Transition mechanisms
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 each other over IPv4-only infrastructure.

IPv6 - Transition mechanisms
Many of these transition mechanisms use tunneling to encapsulate IPv6 traffic within IPv4 networks. This is an imperfect solution, which may increase latency and cause problems with Path MTU Discovery. Tunneling protocols are a temporary solution for networks that do not support native dual-stack, where both IPv6 and IPv4 run independently.

IPv6 - Dual IP stack implementation
Dual-stack (or native dual-stack) refers to side-by-side implementation of IPv4 and IPv6. That is, both protocols run on the same network infrastructure, and there's no need to encapsulate IPv6 inside IPv4 (using ) or vice-versa. Dual-stack is defined in RFC 4213.

IPv6 - Dual IP stack implementation
However, other network equipment (such as a CMTS) or customer equipment (like cable modems) may require software updates or hardware upgrades to support IPv6

IPv6 - Tunneling Because not all networks support dual-stack, tunneling is used for IPv4 networks to talk to IPv6 networks (and vice-versa). Many current internet users do not have IPv6 dual-stack support, and thus cannot reach IPv6 sites directly. Instead, they must use IPv4 infrastructure to carry IPv6 packets. This is done using a technique known as tunneling, which encapsulates IPv6 packets within IPv4, in effect using IPv4 as a link layer for IPv6.

IPv6 - Tunneling IP protocol 41 indicates IPv4 packets which encapsulate IPv6 datagrams. Some routers or network address translation devices may block protocol 41. To pass through these devices, you might use UDP packets to encapsulate IPv6 datagrams. Other encapsulation schemes, such as AYIYA or Generic Routing Encapsulation, are also popular.

IPv6 - Tunneling Conversely, on IPv6-only internet links, when access to IPv4 network facilities is needed, tunneling of IPv4 over IPv6 protocol occurs, using the IPv6 as a link layer for IPv4.

IPv6 - Automatic tunneling
Automatic tunneling refers to a technique by which the routing infrastructure automatically determines the tunnel endpoints. Some automatic tunneling techniques are below.

6to4 is recommended by RFC It 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 the most common tunnel protocol currently deployed.

Teredo is an automatic tunneling technique that uses UDP encapsulation and can allegedly cross multiple NAT nodes. IPv6, including 6to4 and Teredo tunneling, are enabled by default in Windows Vista and Windows 7. Most Unix systems implement only 6to4, but Teredo can be provided by third-party software such as Miredo.

ISATAP 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.

IPv6 - Configured and automated tunneling (6in4)
6in4 tunneling requires the tunnel endpoints to be explicitly configured, either by an administrator manually or the Operating System's configuration mechanisms, or by an automatic service known as a tunnel broker; this is also referred to as automated tunneling

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

IPv6 - 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 IPv6 transition mechanisms must be deployed.

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

NAT-like techniques for application-agnostic translation at the lower layers in routers and gateways have been proposed. The NAT-PT standard was dropped because of criticisms, however more recently the continued low adoption of IPv6 has prompted a new standardization effort of a technology called NAT64.

IPv6 - IPv6 readiness Compatibility with IPv6 networking is mainly a or firmware issue. However, much of the older hardware that could in principle be upgraded is likely to be replaced instead. The American Registry for Internet Numbers (ARIN) suggested that all Internet servers be prepared to serve IPv6-only clients by January Sites will only be accessible over NAT64 if they do not use IPv4 literals as well.

IPv6 - Software Host software can be IPv4-only, IPv6-only, dual-stack, or hybrid dual-stack. Most personal computers running recent Operating System versions are operable on IPv6. Many popular applications with network capabilities are compliant, and most others could be easily upgraded with help from the developers.

IPv6 - Software Some software transitioning mechanisms are outlined in RFC 4038, RFC 3493, and RFC 3542.

IPv6 - IPv4-mapped IPv6 addresses
A deprecated format for IPv4-compatible IPv6 addresses was ::

IPv6 - IPv4-mapped IPv6 addresses
On some systems, e.g., the Linux kernel, NetBSD, and FreeBSD, this feature is controlled by the socket option IPV6_V6ONLY, as specified in RFC 3493.

IPv6 - Hardware and embedded systems
Low-level equipment such as network adapters and network switches may not be affected by the change, since they transmit link-layer frames without inspecting the contents. However, networking devices that obtain IP addresses or perform routing of IP packets do need to understand IPv6.

Most equipment would be IPv6 capable with a software or firmware update if the device has sufficient storage and memory space for the new IPv6 stack. However, manufacturers may be reluctant to spend on software development costs for hardware they have already sold when they are poised for new sales from IPv6-ready equipment.

In some cases, non-compliant equipment needs to be replaced because the manufacturer no longer exists or software updates are not possible, for example, because the network stack is implemented in permanent read-only memory.

The CableLabs consortium published the 160 Mbit/s DOCSIS 3.0 IPv6-ready specification for cable modems in August The widely used DOCSIS 2.0 does not support IPv6. The new 'DOCSIS IPv6' standard supports IPv6, which may on the cable modem side require only a firmware upgrade. It is expected that only 60% of cable modems' servers and 40% of cable modems will be DOCSIS 3.0 by However, most ISPs that support DOCSIS 3.0 do not support IPv6 across their networks.

Other equipment which is typically not IPv6-ready ranges from Voice over Internet Protocol devices to laboratory equipment and printers.

IPv6 - Shadow networks A side effect of IPv6 implementation may be the emergence of so-called "shadow networks" caused by IPv6 traffic flowing into IPv4 networks where the IPv4 security in place is unable to properly identify it. Shadow networks have been found occurring on business networks in which enterprises are replacing Windows XP systems, that do not have an IPv6 stack enabled by default, with Windows 7 systems, which do.

IPv6 - Deployment As of September 2013, about 4% of domain names and 16.2% of the networks on the internet have IPv6 protocol support.

IPv6 - Deployment IPv6 has been implemented on all major Operating Systems in use in commercial, business, and home consumer environments. Since 2008, the domain name system can be used in IPv6. IPv6 was first used in a major world event during the 2008 Summer Olympic Games, the largest showcase of IPv6 technology since the inception of IPv6. Some governments including the Federal U.S. Government and China are also starting to require IPv6 capability on their equipment.

IPv6 - Deployment In 2009, Verizon mandated IPv6 operation and deprecated IPv4 as an optional capability for cellular (LTE) hardware. T-Mobile USA followed suit. As of June 2012, T-Mobile USA supports external IPv6 access.

IPv6 packet Packets consist of control information for addressing and routing, and a payload consisting of user data. The control information in IPv6 packets is subdivided into a mandatory and optional extension headers. The payload of an IPv6 packet is typically a datagram or segment of the higher-level Transport Layer protocol, but may be data for an Internet Layer (e.g., ICMPv6) or Link Layer (e.g., OSPF) instead.

IPv6 packet IPv6 packets are typically transmitted over a Link Layer protocol, such as Ethernet which encapsulates each packet in a frame, but this may also be a higher layer tunneling protocol, such as IPv4 when using 6to4 or Teredo transition technologies.

IPv6 packet Routers do not fragment IPv6 packets, as they do for IPv4. Hosts are "strongly recommended" to implement path MTU discovery to take advantage of MTUs greater than the smallest MTU of 1280 octets. Hosts may use fragmentation to send packets larger than the observed path MTU.

IPv6 packet - Fixed header
The constant 6 (bit sequence 0110).

The bits of this field hold two values. The 6 most-significant bits are used for differentiated services, which is used to classify packets. The remaining two bits are used for ECN; priority values subdivide into ranges: traffic where the source provides congestion control and non-congestion control traffic.

Originally created for giving real-time applications special service. The flow label when set to a non-zero value now serves as a hint to routers and switches with multiple outbound paths that these packets should stay on the same path so that they will not be reordered. It has further been suggested that the flow label be used to help detect spoofed packets.

The size of the payload in octets, including any . The length is set to zero when a Hop-by-Hop extension header carries a Jumbo Payload option.

Specifies the type of the next header. This field usually specifies the transport layer protocol used by a packet's payload. When are present in the packet this field indicates which extension header follows. The values are shared with those used for the IPv4 protocol field, as both fields have the same function (see List of IP protocol numbers).

Replaces the time to live field of IPv4. This value is decremented by one at each intermediate node visited by the packet. When the counter reaches 0 the packet is discarded.

In order to increase performance, and since current link layer technology is assumed to provide sufficient error detection, the header has no checksum to protect it.

IPv6 packet - Extension headers
Extension headers carry optional Internet Layer information, and are placed between the fixed header and the upper-layer protocol header. The headers form a chain, using the Next Header fields. The Next Header field in the fixed header indicates the type of the first extension header; the Next Header field of the last extension header indicates the type of the upper-layer protocol header in the payload of the packet.

All extension headers are a multiple of 8 octets in size; some extension headers require internal padding to meet this requirement.

There are several extension headers defined, and new extension headers may be defined in the future

If a node does not recognize a specific extension header, it should discard the packet and send an Parameter Problem message (ICMPv6 type 4, code 1). When a Next Header value 0 appears in a header other than the fixed header a node should do the same.

Destination Options (before routing header) 60 Options that need to be examined only by the destination of the packet.

Routing 43 Methods to specify the route for a datagram (used with Mobile IPv6).

Authentication Header (AH) 51 Contains information used to verify the authenticity of most parts of the packet.

Encapsulating Security Payload (ESP) 50 Carries encrypted data for secure communication.

Destination Options (before upper-layer header) 60 Options that need to be examined only by the destination of the packet.

Mobility (currently without upper-layer header) 135 Parameters used with Mobile IPv6.

It means that, from the header's point of view, the IPv6 packet ends right after it: the payload should be empty

IPv6 packet - Routing types
Due to the fact that with Routing Header type 0 a simple but effective denial-of-service attack could be launched, this header is deprecated and host and routers are required to ignore these headers.

Routing Header type 1 is used for the Nimrod project funded by DARPA.

Routing Header type 2 is a limited version of type 0 and is used for Mobile IPv6, where it can hold the Home Address of the Mobile Node.

IPv6 packet - Authentication Header (AH) and Encapsulating Security Payload (ESP)
The Authentication Header and the Encapsulating Security are part of IPsec and are used identically in IPv6 and in IPv4.

IPv6 packet - Payload The fixed and optional IPv6 headers are followed with the upper-layer payload, the data provided by the transport layer, for example a TCP segment or a UDP datagram. The Next Header field of the last IPv6 header indicates what type of payload is contained in this packet.

IPv6 packet - Standard payload length
The payload length field of IPv6 (and IPv4) has a size of 16 bits, capable of specifying a maximum size of octets for the payload. Most Link Layer protocols cannot process packets larger than octets.

IPv6 packet - Jumbogram An optional feature of IPv6, the jumbo payload option in a Hop-By-Hop Options extension header, allows the exchange of packets with payloads of up to one byte less than 4 GB (232 − 1 = bytes), by making use of a 32-bit length field. Packets with such payloads are called jumbograms.

IPv6 packet - Jumbogram Since both TCP and UDP include fields limited to 16 bits (length, urgent data pointer), support for IPv6 jumbograms requires modifications to the Transport Layer protocol implementation. Jumbograms are only relevant for links that have a MTU larger than octets (more than octets for the payload, plus 40 octets for the fixed header, plus 8 octets for the Hop-by-Hop extension header).

IPv6 packet - Fragmentation
Unlike in IPv4, IPv6 routers never fragment IPv6 packets. Packets exceeding the size of the maximum transmission unit of the destination link are dropped and this condition is signaled by a Packet too Big ICMPv6 type 2 message to the originating node, similarly to the IPv4 method when the Don't Fragment bit is set.

IPv6 packet - Fragmentation
Any data link layer conveying IPv6 data must be capable of delivering an IP packet containing 1280 bytes without the need to invoke end-to-end fragmentation at the IP layer.

Anycast - IPv6 transition
In IPv4 to IPv6 transitioning, anycast addressing may be deployed to provide IPv6 compatibility to IPv4 hosts. This method, 6to4, uses a default gateway with the IP address , as described in RFC This allows multiple providers to implement 6to4 gateways without hosts having to know each individual provider's gateway addresses.

netsh can also be used to read information from the IPv6 stack.
netsh - netsh and IPv6 netsh can also be used to read information from the IPv6 stack.

To view the IPv6 addresses using netsh:
netsh - netsh and IPv6 To view the IPv6 addresses using netsh:

IPv6 subnetting reference
This IPv6 subnetting reference lists the sizes for IPv6 computer networks. Different types of network links may require different subnet sizes. The CIDR netmask separates the bits of the network identifier prefix from the bits of the interface identifier. Selecting a smaller prefix size results in fewer number of networks covered, but with more addresses within those networks.

Link-local address - IPv6
In the Internet Protocol Version 6 (IPv6), the address block fe80::/10 has been reserved for link-local unicast addressing. The actual link local addresses are assigned with the prefix fe80::/64.[note 2] They may be assigned by automatic (stateless) or stateful (e.g. manual) mechanisms.

Unlike IPv4, IPv6 requires a link-local address to be assigned to every network interface on which the IPv6 protocol is enabled, even when one or more routable addresses are also assigned. Consequently, IPv6 hosts usually have more than one IPv6 address assigned to each of their IPv6-enabled network interfaces. The link-local address is required for IPv6 sublayer operations of the Neighbor Discovery Protocol, as well as for some other IPv6-based protocols, like DHCPv6.

In IPv6, stateless address autoconfiguration is performed as a component of the Neighbor Discovery Protocol (NDP), as specified in RFC The address is formed from its routing prefix and the MAC address of the interface.

IPv6 introduced additional means of assigning addresses to host interfaces

Comparison of IPv6 support in operating systems

This is a comparison of Operating Systems in regards to their support of the IPv6 protocol.

OS Version Claimed IPv6-ready Installed by Default DHCPv6 ND RDNSS

Android 4.2 (Jelly Bean) Partial Yes No No Lacks support for DHCPv6 and ND-RDNSS due to the use of an outdated version of dhcpcd. Suffers from intermittent loss of its unicast address on some phones.

iOS 4.1 Yes Yes Yes Yes iOS supports stateless DHCPv6 since version 4 and stateful DHCPv6 since

OpenBSD 5.2 Yes Yes Addon Yes RDNSS is only supported for rtadvd so far.

Ubuntu to Yes Yes Yes Yes RDNSS support available so long as NetworkManager uses IPv6 "Automatic" setting, otherwise "rdnssd" package required.

Windows NT 5.1 (XP) Yes No Addon No Windows XP users can use Dibbler, an open source DHCPv6 implementation

6.X (Vista),(7),(8) Yes Yes Yes Addon rdnssd-win32 provides an open source implementation of ND RDNSS

Windows Phone 6.5 (Mobile) Yes Yes Lite No If the OEM explicitly unsets the SYSGEN_TCPIP6 pre-processor symbol, the built image will not have any IPv6 capabilities.

7.5 No No No No 8 might have some support.

Comparison of IPv6 support in operating systems - Notes
Operating Systems that do not support either DHCPv6 or ND RDNSS cannot automatically configure name servers in an IPv6-only environment.

Private network - Private IPv6 addresses
The concept of private networks and special address reservation for such networks has been carried over to the next generation of the Internet Protocol, IPv6.

The address block fc00::/7 has been reserved by IANA as described in RFC These addresses are called Unique Local Addresses (ULA). They are defined as being unicast in character and contain a 40-bit random number in the routing prefix to prevent collisions when two private networks are interconnected. Despite being inherently local in usage, the IPv6 address scope of unique local addresses is global.

A former standard proposed the use of so-called "site-local" addresses in the fec0::/10 range, but due to major concerns about scalability and the poor definition of what constitutes a site, its use has been deprecated since September 2004 by RFC 3879.

Private network - IPv6 In IPv6, link-local addresses are codified in RFC Their use is mandatory, and an integral part of the IPv6 standard.

Private network - IPv6 The IPv6 addressing architecture (RFC 4291) sets aside the block fe80::/10 for IP address autoconfiguration.

IPv6 address An Internet Protocol Version 6 address (IPv6 address) is a numerical label that is used to identify a network interface of a computer or other network node participating in an IPv6 computer network.

IPv6 address An IP address serves the purpose of uniquely identifying an individual network interface of a host, locating it on the network, and thus permitting the routing of IP packets between hosts. For routing, IP addresses are present in fields of the packet header where they indicate source and destination of the packet.

IPv6 address IPv6 is the successor to the Internet's first addressing infrastructure, Internet Protocol version 4 (IPv4). In contrast to IPv4, which defined an IP address as a 32-bit value, IPv6 addresses have a size of 128 bits. Therefore, IPv6 has a vastly enlarged address space compared to IPv4.

IPv6 address - IPv6 address classes
IPv6 addresses are classified by the primary addressing and routing methodologies common in networking: unicast addressing, anycast addressing, and multicast addressing.

A unicast address identifies a single network interface. The Internet Protocol delivers packets sent to a unicast address to that specific interface.

An anycast address is assigned to a group of interfaces, usually belonging to different nodes. A packet sent to an anycast address is delivered to just one of the member interfaces, typically the nearest host, according to the routing protocol’s definition of distance. Anycast addresses cannot be identified easily, they have the same format as unicast addresses, and differ only by their presence in the network at multiple points. Almost any unicast address can be employed as an anycast address.

A multicast address is also used by multiple hosts, which acquire the multicast address destination by participating in the multicast distribution protocol among the network routers. A packet that is sent to a multicast address is delivered to all interfaces that have joined the corresponding multicast group.

IPv6 does not implement broadcast addressing. Broadcast's traditional role is subsumed by multicast addressing to the all-nodes link-local multicast group ff02::1. However, the use of the all-nodes group is not recommended, and most IPv6 protocols use a dedicated link-local multicast group to avoid disturbing every interface in the network.

IPv6 address - Address formats
An IPv6 address consists of 128 bits. Addresses are classified into various types for applications in the major addressing and routing methodologies: unicast, multicast, and anycast networking. In each of these, various address formats are recognized by logically dividing the 128 address bits into bit groups and establishing rules for associating the values of these bit groups with special addressing features.

IPv6 address - Multicast address format
For more details on this topic, see Multicast address#IPv6 .

Multicast addresses are formed according to several specific formatting rules, depending on the application.

General multicast address format

The prefix holds the binary value for any multicast address.

Currently, 3 of the 4 flag bits in the flg field are defined; the most-significant flag bit is reserved for future use.

10 P (Prefix) Without prefix information Address based on network prefix

11 T (Transient) Well-known multicast address Dynamically assigned multicast address

The 4-bit scope field (sc) is used to indicate where the address is valid and unique.

There are special multicast addresses, like Solicited Node.

field prefix flg sc zeroes ones unicast address

The sc(ope) field holds the binary value 0010 (link-local). Solicited-node multicast addresses are computed as a function of a node's unicast or anycast addresses. A solicited-node multicast address is created by copying the last 24 bits of a unicast or anycast address to the last 24 bits of the multicast address.

Unicast-prefix-based multicast address format

Link-scoped multicast addresses use a comparable format.

IPv6 address - Presentation
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is:

The hexadecimal digits are case-insensitive, but IETF recommendations suggest the use of lower case letters. The full representation of eight 4-digit groups may be simplified by several techniques, eliminating parts of the representation.

Leading zeroes in a group may be omitted. Thus, the example address may be written as:

One or more consecutive groups of zero value may be replaced with a single empty group using two consecutive colons (::). Thus, the example address can be further simplified:

The localhost (loopback) address, 0:0:0:0:0:0:0:1, and the IPv6 unspecified address, 0:0:0:0:0:0:0:0, are reduced to ::1 and ::, respectively. This two-colon replacement may only be applied once in an address, because multiple occurrences would create an ambiguous representation.

Dotted-quad notation

During the transition of the Internet from IPv4 to the IPv6 it is typical to operate in a mixed addressing environment, and for this purpose a special notation has been introduced to express IPv4-mapped and IPv4-compatible IPv6 addresses by writing the final 32 bits of an address in the familiar IPv4 dotted-quad notation. For example, the IPv4-mapped IPv6 address ::ffff:c000:0280 is usually written as ::ffff: , thus expressing clearly the original IPv4 address that was mapped to IPv6.

IPv6 address - Recommended representation as text
In an attempt to simplify IPv6 addresses, the standards provides flexibility in their representation. However, this also complicates several common operations: searching for a specific address in a text file or stream, and comparing two addresses to determine their equivalence. To mitigate these problems, the IETF has proposed a standard in RFC 5952 for a canonical format for rendering IPv6 addresses in text. Its specific recommendations are:

Leading zeros in each 16-bit field are suppressed. For example, 2001:0db8::0001 is rendered as 2001:db8::1, though any all-zero field that is explicitly presented is rendered as 0.

Representations are shortened as much as possible. The longest sequence of consecutive all-zero fields is replaced by double-colon. For example, 2001:db8:0:0:0:0:2:1 is shortened to 2001:db8::2:1, but 2001:db8:0000:1:1:1:1:1 is rendered as 2001:db8:0:1:1:1:1:1. If there are multiple longest runs of all-zero fields, then it is the leftmost that is compressed. E.g., 2001:db8:0:0:1:0:0:1 is rendered as 2001:db8::1:0:0:1 rather than as 2001:db8:0:0:1::1.

IPv6 address - Networks An IPv6 network uses an address block that is a contiguous group of IPv6 addresses of a size that is a power of two. The leading set of bits of the addresses are identical for all hosts in a given network, and are called the network's address or routing prefix.

IPv6 address - Networks Network address ranges are written in CIDR notation. A network is denoted by the first address in the block (ending in all zeroes), a slash (/), and a decimal value equal to the size in bits of the prefix. For example, the network written as 2001:db8:1234::/48 starts at address 2001:db8:1234:0000:0000:0000:0000:0000 and ends at 2001:db8:1234:ffff:ffff:ffff:ffff:ffff.

IPv6 address - Networks The routing prefix of an interface address may be directly indicated with the address by CIDR notation. For example, the configuration of an interface with address 2001:db8:a::123 connected to subnet 2001:db8:a::/64 is written as 2001:db8:a::123/64.

IPv6 address - Literal IPv6 addresses in network resource identifiers
Colon (:) characters in IPv6 addresses may conflict with the established syntax of resource identifiers, such as URIs and URLs. The colon has traditionally been used to terminate the host path before a port number. To alleviate this conflict, literal IPv6 addresses are enclosed in square brackets in such resource identifiers, for example:

IPv6 address - Literal IPv6 addresses in network resource identifiers
When the URL also contains a port number the notation is:

IPv6 address - Literal IPv6 addresses in UNC path names
IPv6 addresses are transcribed as a hostname or subdomain name within this name space, in the following fashion:

IPv6 address - Literal IPv6 addresses in UNC path names
This notation is automatically resolved by Microsoft software without any queries to DNS name servers. If the IPv6 address contains a zone index, it is appended to the address portion after an 's' character:

IPv6 address - IPv6 address scopes
Every IPv6 address, except the unspecified address (::), has a "scope", which specifies in which part of the network it is valid.

In the unicast addressing class, link-local addresses and the loopback address have link-local scope, which means they are to be used in the directly attached network (link). All other addresses (except Unique local addresses) have global (or universal) scope, which means they are globally routable, and can be used to connect to addresses with global scope anywhere, or addresses with link-local scope on the directly attached network.

Unique local addresses are not globally routable, so their scope is limited to the extent of the network(s) in which they are used. These addresses will only be routed by routers or tunnels whose routing tables have been specifically configured to allow it.

The scope of an anycast address is defined identically to that of a unicast address.

For multicasting, the four least-significant bits of the second address octet of a multicast address (ff0s::) identify the address scope, i.e. the span over which the multicast address is propagated. Currently defined scopes are:

0x1 interface-local Interface-local scope spans only a single interface on a node, and is useful only for loopback transmission of multicast.

0x2 link-local Link-local and site-local multicast scopes span the same topological regions as the corresponding unicast scopes.

0x4 admin-local Admin-local scope is the smallest scope that must be administratively configured, i.e., not automatically derived from physical connectivity or other, non- multicast-related configuration.

0x5 site-local Link-local and site-local multicast scopes span the same topological regions as the corresponding unicast scopes.

0x8 organization-local Organization-local scope is intended to span multiple sites belonging to a single organization.

IPv6 address - General allocation
The IANA has maintained the official list of allocations of the IPv6 address space since December 1995.

Only one eighth of the total address space is currently allocated for use on the Internet, 2000::/3, in order to provide efficient route aggregation, thereby reducing the size of the Internet routing tables; the rest of the IPv6 address space is reserved for future use or for special purposes. The address space is assigned to the RIRs in large blocks of /23 up to /12.

The RIRs assign smaller blocks to local Internet registries that distributes them to users. These are typically in sizes from /19 to /32. The addresses are typically distributed in /48 to /56 sized blocks to the end users.

Global unicast assignment records can be found at the various RIRs or other websites.

The total pool, however, is sufficient for the foreseeable future, because there are 2128 or about 3.4×1038 (340 trillion trillion trillion) unique IPv6 addresses.

Each RIR can divide each of its multiple /23 blocks into 512 /32 blocks, typically one for each ISP; an ISP can divide its /32 block into /48 blocks, typically one for each customer; customers can create /64 networks from their assigned /48 block, each having 264 addresses. In contrast, the entire IPv4 address space has only 232 (about 4.3×109) addresses.

By design, only a very small fraction of the address space will actually be used. The large address space ensures that addresses are almost always available, which makes the use of network address translation (NAT) for the purposes of address conservation completely unnecessary. NAT has been increasingly used for IPv4 networks to help alleviate IPv4 address exhaustion.

IPv6 address - Reserved anycast addresses
The lowest address within each subnet prefix (the interface identifier set to all zeroes) is reserved as the "subnet-router" anycast address. Applications may use this address when talking to any one of the available routers, as packets sent to this address are delivered to just one router.

IPv6 address - Reserved anycast addresses
The address with value 0x7e in the 7 least-significant bits is defined as a mobile IPv6 home agents anycast address

IPv6 address - Unspecified address
::/128 — The address with all zero bits is called the unspecified address (corresponding to /32 in IPv4).

IPv6 address - Local addresses
::1/128 — The loopback address is a unicast localhost address. If an application in a host sends packets to this address, the IPv6 stack will loop these packets back on the same virtual interface (corresponding to /8 in IPv4).

IPv6 address - Local addresses
A link-local address is required on every IPv6-enabled interface—in other words, applications may rely on the existence of a link-local address even when there is no IPv6 routing

IPv6 address - Transition from IPv4
Transmission is handled similarly; established sockets may be used to transmit IPv4 or IPv6 datagram, based on the binding to an IPv6 address, or an IPv4-mapped address

::ffff:0:0:0/96 — A prefix used for IPv4-translated addresses which are used by the Stateless IP/ICMP Translation (SIIT) protocol.

64:ff9b::/96 — The "Well-Known" Prefix. Addresses with this prefix are used for automatic IPv4/IPv6 translation.

2002::/16 — This prefix is used for 6to4 addressing. Here, an address from the IPv4 network /24 is also used.

IPv6 address - Special-purpose addresses
IANA has reserved a so-called 'Sub-TLA ID' address block for special assignments which consists of 64 network prefixes in the range 2001:0000::/29 through 2001:01f8::/29. Three assignments from this block have been made:

2001::/32 — Used for Teredo tunneling (which also falls into the category of IPv6 transition mechanisms).

2001:2::/48 — Assigned to the Benchmarking Methodology Working Group (BMWG) for benchmarking IPv6 (corresponding to /15 for benchmarking IPv4).

2001:10::/28 — ORCHID (Overlay Routable Cryptographic Hash Identifiers). These are non-routed IPv6 addresses used for Cryptographic Hash Identifiers.

IPv6 address - Documentation
2001:db8::/32 — This prefix is used in documentation. The addresses should be used anywhere an example IPv6 address is given or model networking scenarios are described (corresponding to /24, /24, and /24 in IPv4.)

IPv6 address - Multicast addresses
The multicast addresses ff00::0/8 are reserved and should not be assigned to any multicast group. The Internet Assigned Numbers Authority (IANA) manages address reservations.

Some common IPv6 multicast addresses are the following:

ff0X::1 All nodes address, identify the group of all IPv6 nodes Available in scope 1 (interface-local) and 2 (link-local):

ff0X::2 All routers Available in scope 1 (interface-local), 2 (link-local) and 5 (site-local):

ff01::2 → All routers in the interface-local

ff02::2 → All routers in the link-local

ff05::2 → All routers in the site-local

ff02::6 OSPFIGP Designated Routers 2 (link-local)

ff02::9 RIP Routers 2 (link-local)

ff02::a EIGRP Routers 2 (link-local)

ff02::d All PIM Routers 2 (link-local)

ff02::1a All RPL Routers 2 (link-local)

ff02::1:3 Link-local Multicast Name Resolution 2 (link-local)

ff02::2:ff00:0/104 Node Information Queries 2 (link-local)

IPv6 address - Stateless address autoconfiguration
On system startup, a node automatically creates a link-local address on each IPv6-enabled interface, even if globally routable addresses are manually configured or obtained through "configuration protocols" (see below). It does so independently and without any prior configuration by stateless address autoconfiguration (SLAAC), using a component of the Neighbor Discovery Protocol. This address is selected with the prefix fe80::/64.

In IPv4, typical "configuration protocols" include DHCP or PPP. Although DHCPv6 exists, IPv6 hosts normally use the Neighbor Discovery Protocol to create a globally routable unicast address: the host sends router solicitation requests and an IPv6 router responds with a prefix assignment.

The lower 64 bits of these addresses are populated with a 64-bit interface identifier in format. This identifier is usually shared by all automatically configured addresses of that interface, which has the advantage that only one multicast group needs to be joined for neighbor discovery. For this, a multicast address is used, formed from the network prefix ff02::1:ff00:0/104 and the 24 least significant bits of the address.

IPv6 address - Modified EUI-64
To create an IPv6 address with the network prefix 2001:db8:1:2::/64 it yields the address 2001:db8:1:2:020c:29ff:fe0c:47d5 (with the underlined U/L bit inverted to a 1, because the MAC address is universally unique).

IPv6 address - Duplicate address detection
The assignment of a unicast IPv6 address to an interface involves an internal test for the uniqueness of that address using Neighbor Solicitation and Neighbor Advertisement (ICMPv6 type 135 and 136) messages. While in the process of establishing uniqueness an address has a tentative state.

The node joins the solicited-node multicast address for the tentative address (if not already done so) and sends neighbor solicitations, with the tentative address as target address and the unspecified address (::/128) as source address. The node also joins the all-hosts multicast address ff02::1, so it will be able to receive Neighbor Advertisements.

If a node receives a neighbor solicitation with its own tentative address as the target address, then that address is not unique. The same is true if the node receives a neighbor advertisement with the tentative address as the source of the advertisement. Only after having successfully established that an address is unique may it be assigned and used by an interface.

IPv6 address - Address lifetime
Each IPv6 address that is bound to an interface has a fixed lifetime. Lifetimes are infinite, unless configured to a shorter period. There are two lifetimes that govern the state of an address: the preferred lifetime and the valid lifetime. Lifetimes can be configured in routers that provide the values used for autoconfiguration, or specified when manually configuring addresses on interfaces.

IPv6 address - Address lifetime
When an address is assigned to an interface it gets the status "preferred", which it holds during its preferred-lifetime. After that lifetime expires the status becomes "deprecated" and no new connections should be made using this address. The address becomes "invalid" after its valid-lifetime also expires; the address is removed from the interface and may be assigned somewhere else on the Internet.

IPv6 address - Temporary addresses
To reduce the prospect of a user identity being permanently tied to an IPv6 address portion, a node may create temporary addresses with interface identifiers based on time-varying random bit strings and relatively short lifetimes (hours to days), after which they are replaced with new addresses.

Temporary addresses may be used as source address for originating connections, while external hosts use a public address by querying the Domain Name System.

Network interfaces configured for IPv6 use temporary addresses by default in OS X Lion or later Apple systems, and in Windows Vista, Windows 2008 Server or later Microsoft systems.

IPv6 address - Default address selection
IPv6-enabled network interfaces usually have more than one IPv6 address, for example, a link-local and a global address, and permanent versus temporary addresses. IPv6 introduces the concepts of address scope and selection preference, yielding multiple choices for source and destination address selections in communication with another host.

The preference selection algorithm, which selects the most appropriate address to use in communications with a particular destination (including the use of IPv4-mapped addresses in dual-stack implementations), is based on a user-customizable preference table that associates each routing prefix with a precedence level. The default table is as follows:

The default configuration places preference on IPv6, rather than IPv4, and on destination addresses within the smallest possible scope, so that link-local communication is preferred over globally routed paths when otherwise equally suitable

IPv6 address - Link-local addresses and zone indices
Because all link-local addresses in a host have a common prefix, normal routing procedures cannot be used to choose the outgoing interface when sending packets to a link-local destination. A special identifier, known as a zone index, is needed to provide the additional routing information; in the case of link-local addresses, zone indices correspond to interface identifiers.

When an address is written textually, the zone index is appended to the address, separated by a percent sign (%). The actual syntax of zone indices depends on the Operating System:

the Microsoft Windows IPv6 stack uses numeric zone indexes, e.g., fe80::3%1. The index is determined by the interface number;

most Unix-like systems (e.g., BSD, Linux, OS X) use the interface name as a zone index: fe80::3%eth0.

Zone index notations cause syntax conflicts when used in uniform resource identifiers (URI), so the '%' character must be escaped via percent-encoding:

IPv6 address - IPv6 addresses in the Domain Name System
In the Domain Name System hostnames are mapped to IPv6 addresses by AAAA resource records, so-called quad-A records. For reverse lookup the IETF reserved the domain ip6.arpa, where the name space is hierarchically divided by the 1-digit hexadecimal representation of nibble units (4 bits) of the IPv6 address. This scheme is defined in RFC 3596.

As in IPv4, each host is represented in the DNS by two DNS records, an address record and a reverse mapping pointer record. For example, a host computer named justin in zone example.com has the Unique Local Address fdda:5cc1:23:4::1f. Its quad-A address record is

justin.example.com. IN AAAA fdda:5cc1:23:4::1f

f c.c.5.a.d.d.f.ip6.arpa. IN PTR justin.example.com.

This pointer record may be defined in a number of zones, depending on the chain of delegation of authority in the zone d.f.ip6.arpa.

The DNS protocol is independent of its Transport Layer protocol. Queries and replies may be transmitted over IPv6 or IPv4 transports regardless of the address family of the data requested.

IPv6 address - Transition challenges
Use of the Happy Eyeballs algorithm by client software can mitigate this problem, by trying both IPv6 and IPv4 connections simultaneously, then using whichever connects first.

IPv6 address - Deprecated and obsolete addresses
The site-local prefix fec0::/10 specifies that the address is valid only within the site network of an organization. It was part of the original addressing architecture in December 1995, but its use was deprecated in September 2004 because the definition of the term site was ambiguous, which led to confusing routing rules. New networks must not support this special type of address. In October 2005, a new specification replaced this address type with unique local addresses.

The address block 0200::/7 was defined as an OSI NSAP-mapped prefix set in August 1996, but was deprecated in December 2004.

The only remaining use of this address format is to represent an IPv4 address in a table or database with fixed size members that must also be able to store an IPv6 address.

Address block 3ffe::/16 was allocated for test purposes for the 6bone network in December Prior to that, the address block 5F00::/8 was used for this purpose. Both address blocks were returned to the address pool in June 2006.

IPv6 address - Miscellany
IPv6 addresses were originally registered in the Domain Name System (DNS) in the ip6 zone under the int top-level domain for reverse lookups. In 2000, the Internet Architecture Board (IAB) reverted their intentions to retire arpa, and decided in 2001 that the arpa top-level domain should retain its original function. Domains in ip6.int should be moved to ip6.arpa. The ip6.int zone was officially removed on 6 June 2006.

IPv6 address - Miscellany
In March 2011, the IETF refined their recommendations for allocation of address blocks to end sites. Instead of assigning either a /48, /64, or /128 (according to IAB's and IESG's views of 2001), Internet service providers should consider assigning smaller blocks (for example a /56) to end users. The ARIN, RIPE & APNIC regional registries' policies encourage /56 assignments where appropriate.

4G - IPv6 support Unlike 3G, which is based on two parallel infrastructures consisting of circuit switched and packet switched network nodes, 4G will be based on packet switching only. This will require low-latency data transmission.

4G - IPv6 support By increasing the number of IP addresses available, IPv6 removes the need for network address translation (NAT), a method of sharing a limited number of addresses among a larger group of devices, although NAT will still be required to communicate with devices that are on existing IPv4 networks.

4G - IPv6 support As of June 2009, Verizon has posted specifications that require any 4G devices on its network to support IPv6.

IPv6 deployment Internet Protocol Version 6 (IPv6) is the next generation of the Internet Protocol that is in various stages of deployment on the Internet. It was designed as a replacement for the current version, IPv4, that has been in use since 1982 and is in the final stages of exhausting its unallocated address space.

IPv6 deployment In December 2008, despite marking its 10th anniversary as a Standards Track protocol, IPv6 still accounted for a minuscule fraction of the used addresses and the traffic in the publicly accessible Internet which is still dominated by IPv4

IPv6 deployment In October 2011, 263 (85%) of the 294 top-level domains (TLDs) in the Internet supported IPv6 to access their domain name servers, and 234 (76%) zones contained IPv6 glue records, and approximately 3.4 million domains (3%) had IPv6 address records in their zones. Of all networks in the global BGP routing table, 12% have IPv6 protocol support.

IPv6 deployment Some implementations of the BitTorrent peer-to-peer file transfer protocol make use of IPv6 to avoid NAT issues common for IPv4 private networks.

IPv6 deployment The specification mandates IPv6 operation according to the 3GPP Release 8 Specifications , and deprecates IPv4 as an optional capability.

IPv6 deployment In the early 2000s, governments increasingly required support for IPv6 in new equipment. The U.S. government, for example, specified in 2005 that the network backbones of all federal agencies had to be upgraded to IPv6 by June 30, 2008; this was completed before the deadline. The government of People's Republic of China implemented a five-year plan for deployment of IPv6 called the China Next Generation Internet (see below).

IPv6 deployment Major providers of Internet services, both ISPs and content providers, also began to implement IPv6 access into their products.

IPv6 deployment - Deployment evaluation tools
A global view into the growing IPv6 routing tables can be obtained with the SixXS Ghost Route Hunter. This tool provides a list of all allocated IPv6 prefixes and marks with colors the ones that are actually being announced into the Internet BGP tables. When a prefix is announced, it means that the ISP at least can receive IPv6 packets for their prefix.

IPv6 deployment - Deployment evaluation tools
The integration of IPv6 on existing network infrastructures current at any time can also be monitored from other sources, for example:

IPv6 deployment - IPv6 testing, evaluation, and certification
A few organizations are involved with international IPv6 test and evaluation, ranging from the United States Department of Defense to the University of New Hampshire.

The US DoD Joint Interoperability Test Command DoD IPv6 Product Certification Program

University of New Hampshire InterOperability Laboratory involvement in the IPv6 Ready Logo Program

IPv6 deployment - Major milestones
1996 Alpha quality IPv6 support in Linux kernel development version

6bone (an IPv6 virtual network for testing) is started.

1997 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, are made available.

1998 Microsoft Research releases its first experimental IPv6 stack. This support is not intended for use in a production environment.

1999 In February, the IPv6 Forum is founded by the IETF Deployment WG to drive deployment worldwide. This results in the creation of regional and local IPv6 Task Forces.

2000 Production-quality BSD support for IPv6 becomes generally available in early to mid-2000 in FreeBSD, OpenBSD, and NetBSD via the KAME project.

Sun Solaris supports IPv6 in Solaris 8 in February.

2001 In January, Compaq ships IPv6 with OpenVMS.

Cisco Systems introduces IPv6 support on Cisco IOS routers and L3 switches.

On April 23, 2001, the European Commission launches the European IPv6 Task Force

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.

IBM z/OS supports IPv6 since version 1.4 (general availability in September 2002).

2003 Apple Mac OS X v10.3 "Panther" (2003) supports IPv6 which is enabled by default.

2004 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 The IPv6 records for France (fr) are added later. This makes IPv6 DNS publicly operational.

2005 Linux removes experimental status from its IPv6 implementation.

2007 Microsoft Windows Vista (2007) supports IPv6 which is enabled by default.

Apple's AirPort Extreme n base station includes an IPv6 gateway in its default configuration. It uses 6to4 tunneling and manually configured static tunnels. (Note: 6to4 was disabled by default in later firmware revisions.)

2008 On February 4, 2008, IANA adds AAAA records for the IPv6 addresses of six root name servers. With this transition, it is now possible to resolve domain names using only IPv6.

On March 12, 2008, IETF does an hour long IPv4 blackout at its meeting as an opportunity to capture informal experience data to inform protocol design work going forward; this led to many fixes in Operating Systems and applications.

On May 27, 2008, the European Commission publish their Action Plan for the deployment of Internet Protocol version 6 (IPv6) in Europe, with the aim of making IPv6 available to 25% of European users by 2010.

2011 On June 8, 2011 the Internet Society together with several other big companies and organizations held World IPv6 Day, a global 24 hour test of IPv6.

2012 On June 6, 2012 the Internet Society together with many other big companies and organizations held World IPv6 Launch Day, a global permanent deployment of IPv6.

IPv6 deployment - Australia
AARNet completed network AARNet 3, a high-speed network connecting academic and research customers in the major metropolitan centres, with international links to major ISPs in the US, Asia, and Europe. One of the design goals was to support both IPv4 and IPv6 protocols equally. It also supports multicast routing and jumbo frames.

IPv6 Now Pty Ltd introduced the first commercial-grade IPv6 tunnel broker service in Australia on April 30, Also, in June 2008, IPv6Now introduced the first dual stacked (IPv4 & IPv6) web hosting service.

Internode is the first commercial ISP in Australia to have full IPv6 connectivity and make IPv6 available to customers. The availability to customers was officially announced to Whirlpool on July 18, 2008.

The Victorian State Government granted A$350,000 to establish an IPv6 testbed network (VIC6) freely available to industry to evaluate their IPv6 products and strategies.

Telstra announced on 5 September 2011 that their backbone network was fully double-stacked and that they had commenced providing its enterprise, government and wholesale customers with IPv6 connectivity, and helping customers through the transition.

IPv6 deployment - Belgium
On July , native IPv6 over UMTS/GPRS was successfully tested in Belgium and The Netherlands within a vehicle platform as an Intelligent transportation system solution. The test was performed both in gsm and in tethering mode using a Nokia smart-phone. This test was performed by Logica Netherlands within the SPITS project, in cooperation with Mobistar Belgium.

Since September 2003 research and government ISP Belnet offers native IPV6 to all customers.

VOO A large residential ISP (cable) started its transition in April 2013 leading to impressive growth in IPv6 in Belgium

IPv6 deployment - Canada
At this time, IPv6 deployment is slow but ongoing, with major western Canadian ISPs (notably Shaw Communications, Distributel and TELUS) lacking in support for its residential customers, and the majority of their business customers (including server packages).

Fibrenoire, a Canadian Metro Ethernet fibre network operating in Quebec and Ontario, has been providing native IPv6 connectivity since 2009.

TekSavvy has deployed their own IPv6 network to customers as a Beta. This service is strictly on an opt-in basis.

Videotron has deployed their own IPv6 network to customers as a beta service

IPv6 deployment - China The events were streamed live over the Internet and networked cars were able to monitor traffic conditions readily, all network operations of the Games being conducted using IPv6.

IPv6 deployment - China Also, the CERNET (China Education and Research NETwork, 中国教育和科研计算机网, 教育网) set up native IPv6 (CERNET2), and since then many academic institutions in China joined CERNET2 for IPv6 connectivity. CERNET-2 is probably the widest deployment of IPv6 in China. It is managed and operated jointly by 25 universities. Students in Shanghai Jiao Tong University and Beijing University of Posts and Telecommunications, for example, get native IPv6.

IPv6 deployment - Finland
FICORA (Finnish Communications Regulatory Authority), the NIC for the .fi top level domain, has added IPv6 address to DNS servers, and allows entering IPv6 address when registering domains. The registration service domain.fi for new domains is also available over IPv6.

IPv6 deployment - Finland
Nebula, a Finnish ISP offers IPv6 access since 2007

IPv6 deployment - France
Renater, the French national academical network, is offering IPv6 connectivity including multicast support to their members.

Free, a major French ISP, rolled-out IPv6 at end of year 2007.

Orange: official support could be gone during [not in citation given]

Numericable since 2012 with a specific subscription

Bouygues Telecom may be in the end 2012

IPv6 deployment - Germany
M-net, a regional carrier and ISP, offers an IPv6 PoP and native IPv6 (currently beta, to your username) for their customers.

The 6WIN backbone network by the JOIN Team offers full native IPv6 support for their participants. Many scientific networks in Germany, like the Munich Scientific Network (MWN) operated by Leibniz-Rechenzentrum, are connected to this network.

According to a list maintained by the SiXXS project, there are about seven providers who offer native IPv6 or combined native IPv6/native IPv4-connectivity over the T-DSL network at the end of 2009.

Deutsche Telekom started rolling out IPv6 for new All-IP T-DSL customers in September The overall deployment rate was 2.75% by 15th April 2013.

Regional carrier and ISP NetCologne has begun offering native IPv6 to its customers in a field test. Users wanting to participate can do so by sending an request to customer services

IPv6 deployment - Hungary
In Hungary Externet was the first ISP starting deploying IPv6 on its network in 2008 August. The service was commercially available since 2009 May.

Magyar Telekom was running tests on its production environments since the beginning of Free customer trials started on November 2, 2009 for those on ADSL or Fiber Optic. Customers are given a /128 via DHCP-ND unless they register their DUID in which case they receive a /56 - using a static configuration results in a single /64.

According to information on telecompaper.com, UPC Hungary will start deploying IPv6 in mid-2013, finishing it in 2013.

So far no other Hungarian ISP offers IPv6 connectivity.

IPv6 deployment - India Department of Telecommunications, of Government of India is running a program for adoption of IPv6 in the Government network.

IPv6 deployment - India TEC (Telecommunication Engineering Center) is writing specification for IPv6 certification.

IPv6 deployment - India Sify Technologies Limited, a private Internet service provider, rolled out IPv6 in Sify has a dual-stack network that supports commercial services on IPv6 transport for its enterprise customers. Sify is a sponsored member of 6Choice, a project by India-Europe cooperation to promote IPv6 adoption. Sify is the first to launch a dual-stack commercial portal Users were notified about the version of IP they use when they are accessing the front-page.

IPv6 deployment - India ERNET is setting up an IPv6 central facility aimed at system and network administrators to provide hands-on training in the use and configuration of web, mail, proxy, DNS and other such servers on IPv6.

IPv6 deployment - Japan Telecommunications company NTT announces itself as the world's first ISP to offer public availability of IPv6 services in March 2000.

IPv6 deployment - Luxembourg
RESTENA, the national research and education network, has been running IPv6 for a number of years. It is connected to the European GEANT2 network. In addition, it runs one of the country Internet exchanges, which supports IPv6 peering. RESTENA also runs the .lu top level domain, which also supports IPv6.

IPv6 deployment - Luxembourg
P&T Luxembourg, main telecom and Internet service providers, has announced they have production quality IPv6 connectivity since January 2009, with the first professional customers being connected as of September Deployment of IPv6 to residential customers is expected to take place in 2010.

IPv6 deployment - Netherlands
SURFnet, maintainer of the Dutch academical network SURFnet, introduced IPv6 to its network 1997, in the beginning using IPv6-to-IPv4 tunnels. Its backbone is entirely running dual-stack, supporting both native IPv4 and IPv6 to most of its users.

XS4All is a major Dutch ISP. In 2002 XS4All was the first Dutch broadband provider to introduce IPv6 to its network, but it has only been experimental. In May 2009 the provider provided the first native IPv6 DSL connections. As of August 2010 native IPv6 DSL connections became available to almost all their customers. Since June 2012 native IPv6 is enabled by default for all new customers.

Business-orientated Internet provider BIT BV has been providing IPv6 to all their customers (DSL, FTTH, colocated) since 2004.

SixXS has two private Dutch founders and has been partnering with IPv6 Internet service providers in many countries to provide IPv6 connectivity via IP tunnels to users worldwide since It started out as IPng.nl with a predominantly Dutch user base and reorganized as SixXS to be able to reach users internationally and be diversified in ISP support. SixXS also provides various other related services and software which contributed significantly to IPv6 adoption and operation globally.

Business ISP Introweb provides an IPv6-only 8 Mbit/s ADSL connection for 6 euro per month to 100 customers as a pilot, both for companies to learn how to adapt to IPv6 as for themselves in working on a fully IPv6 enabled network.

Signet is the first ISP in the country which provides IPv6 connectivity together with IPv4 on multiple national fiber networks (Eurofiber, Glasvezel Eindhoven, BRE, Glasnet Veghel, Ziggo, and Fiber Port).

Most Dutch hosting companies, including the biggest one, Leaseweb, support IPv6, but customers by default get only IPv4 address.

Several government sites (such as Rijksoverheid.nl) are available via IPv6.

IPv6 deployment - New Zealand
An increasing number of New Zealand Government websites are available over IPv6, including the Ministry of Defence (New Zealand), Ministry for Primary Industries (New Zealand), Ministry of Social Development and the Department of Internal Affairs.

Massey University has enabled IPv6 on its border and core campus routers. Its central network services, including DNS, external and NTP are also enabled. Massey’s main website is IPv6-enabled and remote login to some servers and network equipment also support IPv6 for systems administration and networking staff.

A number of internal servers and client devices communicate via IPv6, and a teredo relay and 6to4 relay ensure users using these two transition technologies are well served when accessing IPV6 addresses.

The University of Auckland IT Services team has partially deployed IPv6, in collaboration with the Science Faculty and the Computer Science Department. It has IPv6 connectivity via KAREN and its commercial ISP. Computer Science is fully dual-stacked; IPv6 has been used in undergraduate laboratory assignments and for post-graduate projects.

New Zealand data centre and Internet services firm Unleash provides native, wholesale and business grade IPv6 transit nationwide, as well as operating both 6to4 and Teredo relays on its network.

Auckland-based ISP WorldxChange Communications has had dual-stack since It has started providing residential customers with dual (IPv4 and IPv6) service using DHCPv6, on a trial basis.

Government Technology Services, a business group of the Department of Internal Affairs (DIA), has an IPv6 website as a proof of concept to demonstrate how New Zealand government websites can be made accessible to the IPv6 Internet. Government Technology Services has also set up an IPv6 address schema.

South Island-based Internet Service Provider Snap Internet provides native IPv6 connectivity for all its customers. Its network is fully IPv6-enabled, with the IPv6 service running alongside Snap’s normal IPv4 connectivity.

New Zealand Internet Backbone Provider FX Networks offers native IPv6 support for its customers. It is a full production service with parallel dual stack support for both IPv4 and IPv6. FX also supports IPv6 transport on its private IP enterprise WAN service.

Internet Service Provider DTS's transit, managed and hosting services are fully IPv6 capable.

Trans-Tasman service provider Vocus Communications offers full dual-stack IP transit services.

IPv6 deployment - Philippines
The government is in process of upgrading its facilities. Globe Telecom has already set in motion the transition of its core IP network to IPv6, noting that it is now fully prepared even as the Internet runs out of IPv4 addresses. Globe claims it is the first local telecommunication company to test IPv6 with Department of Science and Technology (Philippines). In some cases, like test networks or users, IPv6 or both maybe present.

IPv6 deployment - Poland
The Polish national research and education network began an IPv6 trial period in As for now native IPv6 connectivity is available to numerous educational and private clients connected via citywide networks operated by local universities.

Polish Internet Exchange, a commercial and carrier-neutral Internet traffic exchange point, has facilitated IPv6 peering between numerous operators since 2008.

Orange Polska - (mobile operator) March 2013 launched mobile access to the Internet via IPv6 protocol for their subscribers.

IPv6 deployment - Romania
As of June 2012, the ISP named RCS&RDS offers dual stack IPv4/IPv6 PPPoE services to current home users using modern versions of Microsoft Windows, Mac OS X, Linux and other IPv6-ready devices. More than 1 million RCS & RDS residential customers can now use native IPv6 on a dual stack PPPoE connection and 20% already do.

IPv6 deployment - Sweden
Bahnhof offers IPv6 to both consumers and businesses.

IPv6 deployment - Sweden
Operators offering native IPv6 access for business clients and collocation customers include:

IPv6 deployment - United Kingdom
JANET, the UK's education and research network, introduced IPv6 unicast support into its service level agreement in Several major UK universities (e.g., Cambridge) upgraded their campus routing infrastructure to provide IPv6 unicast support to their users.

Andrews & Arnold launched a native (non-tunneled) IPv6 service in October 2005 and offer IPv6 by default

The UK Government started to replace much of its Government Secure Intranet (a Wide Area Network) with a new Public Services Network (PSN) in late The aspiration was to deploy using IPv6 and support IPv4. The implementation is based on IPv4 but suppliers must be capable of supporting IPv6.

IPv6 deployment - United States
As with IPv4, the Department of Defense holds a larger IPv6 allocation than any other entity, a /13 block, enough to create almost 9 trillion (9×1012) local area networks, and 64 times as many as the next largest entity.

Hurricane Electric (AS6939), a Fremont, California Internet backbone and colocation provider, was an early IPv6 adopter and maintains a native IPv6 backbone and as of 2008 was one of the largest IPv6 connectivity and hosting providers in the United States. It was the first IPv6 backbone operator in the world to reach 200 IPv6 BGP adjacencies. Through its IPv6 tunnel broker service, Hurricane also provides free IPv6 connectivity to users in the United States and in several .

Sonic.net, a Santa Rosa, California-based Internet provider, offers partial support for IPv6. They assign a /60 to any customer requesting address space and deliver the IPv6 packets over a 6in4 tunnel. The RDNS authoritative servers for the assigned IPv6 space do answer IPv6 requests, but the recursive DNS servers provided for customer use are IPv4-only.

AT&T started testing their networks with IPv6 in 2006 and started rolling out IPv6 to customers with compatible CPEs in Q

Time Warner Cable was conducting IPv6 trials for their customers from September 2011.

U.S. Department of Education (ED) became the first cabinet-level agency to deploy IPv6 on its DNS services across its 17 .gov domains on August 5, 2012.

Google Fiber launched with IPv6 support in 2012

Charter Communications offers IPv6 access to all of its customers via a freely accessible IPv6 rapid deployment server since at least March of 2012.

Verizon Wireless the largest US Mobile operator is also the leading deployer of IPv6. As of September 2013, over 33% of all users on Verizon also had IPv6.

IPv6 deployment - Other countries
Bulgaria has constructed a research center to study the possibilities of adopting IPv6 in the country. The center is to operate alongside another facility, which is equipped with an IBM Blue Gene/P supercomputer.

IPv6 deployment - World IPv6 Day
The Internet Society promoted June 8, 2011, as "World IPv6 Day". The event was described as a "test drive" for full IPv6 rollouts.

IPv6 deployment - World IPv6 Launch
The Internet Society declared June 6, 2012 to be the date for "World IPv6 Launch", with participating major websites enabling IPv6 permanently, participating ISPs offering IPv6 connectivity, and participating router manufacturers offering devices enabled for IPv6 by default.

Multicast address - IPv6
Multicast addresses in IPv6 have the prefix ff00::/8. IPv6 multicast addresses are generally formed from four bit groups, illustrated as follows:

Field prefix flags scope group ID

The prefix holds the binary value for any multicast address. Currently, 3 of the 4 flag bits in the flags field are defined; the most-significant flag bit is reserved for future use. The other three flags are known as R, P and T.

2 P (Prefix) Without prefix information Address based on network prefix

3 (LSB) T (Transient) Well-known multicast address Dynamically assigned multicast address

Similar to unicast addresses, the prefix of IPv6 multicast addresses specifies their scope, however, the set of possible scopes is different. The 4-bit sc (or scope) field (bits 12 to 15) is used to indicate where the address is valid and unique.

IPv6 address[note 1] IPv4 equivalent Scope Purpose

ffx1::/ /8 Interface-local Packets with this destination address may not be sent over any network link, but must remain within the current node; this is the multicast equivalent of the unicast loopback address.

ffx2::/ /24 Link-local Packets with this destination address may not be routed anywhere.

ffx4::/16 Admin-local The smallest scope that must be administratively configured.

ffx8::/ /14 Organization-local Restricted to networks used by the organization administering the local network. (For example, these addresses might be used over VPNs; when packets for this group are routed over the public internet (where these addresses are not valid), they would have to be encapsulated in some other protocol.)

ffxe::/ Global scope Eligible to be routed over the public internet.

The service is identified in the 112-bit Group ID field. For example, if ff02::101 refers to all Network Time Protocol (NTP) servers on the local network segment, then ff08::101 refers to all NTP servers in an organization's networks. The Group ID field may be further divided for special multicast address types.

The following table is a partial list of well-known IPv6 multicast addresses that are registered with the Internet Assigned Numbers Authority (IANA).

Comparison of IPv6 support by major transit providers
Internet Protocol Version 6 (IPv6) is not yet universally available as of 2012, but support by major ISPs and transit providers is steadily increasing. Many major transit providers offer an IPv6 service to their customers, but do not have a ubiquitous view of all other IPv6 networks. Other aspects of this service vary widely from one major ISP to the next.

Network ASN Routes Carried[note 1] Customer Routes[note 2] Maximum Prefix Length Partitioned From[note 3] Updated[note 4]

Cogent Communications[note 6] 174 8,852 AS6939, AS3257, AS

Level 3 Communications ,072 4,504 /

nLayer Communications (now Global Telecom & Technology) , /

Inteliquent (formerly Tinet now Global Telecom & Technology) ,842 3,133 /48 AS

Split tunneling - IPv6 dual-stack networking
Internal IPv6 content can be hosted and presented to sites via a unique local address range at the VPN level, while external IPv4 & IPv6 content can be accessed via site routers.

Transmission Control Protocol - TCP checksum for IPv6
When TCP runs over IPv6, the method used to compute the checksum is changed, as per RFC 2460:

Any transport or other upper-layer protocol that includes the addresses from the IP header in its checksum computation must be modified for use over IPv6, to include the 128-bit IPv6 addresses instead of 32-bit IPv4 addresses.

A pseudo-header that mimics the IPv6 header for computation of the checksum is shown below.

TCP pseudo-header for checksum computation (IPv6)

320 Source port Destination port

Source address – the one in the IPv6 header

Destination address – the final destination; if the IPv6 packet doesn't contain a Routing header, TCP uses the destination address in the IPv6 header, otherwise, at the originating node, it uses the address in the last element of the Routing header, and, at the receiving node, it uses the destination address in the IPv6 header.

User Datagram Protocol - IPv6 Pseudo Header
When UDP runs over IPv6, the checksum is mandatory. The method used to compute it is changed as documented in RFC 2460:

When computing the checksum, again a pseudo header is used that mimics the real IPv6 header:

Source Port Destination Port

The destination address is the final destination; if the IPv6 packet does not contain a Routing header, that will be the destination address in the IPv6 header; otherwise, at the originating node, it will be the address in the last element of the Routing header, and, at the receiving node, it will be the destination address in the IPv6 header

Multihoming - IPv6 multihoming
Ecessa article on multihoming

Multihoming - IPv6 multihoming
Internet-Draft: Analysis of IPv6 Multihoming Scenarios

Facebook Places - IPv6 According to a June 2010 report by Network World, Facebook said that it was offering experimental, non-production support for IPv6, the long-anticipated upgrade to the Internet's main communications protocol. The news about Facebook's IPv6 support was expected; Facebook told Network World in February 2010, that it planned to support native IPv6 user requests by the midpoint of this year.

Facebook Places - IPv6 In addition, Facebook enabled IPv6 on its main domain names during World IPv6 Launch.

Three way handshake - TCP checksum for IPv6
:Any transport or other upper-layer protocol that includes the addresses from the IP header in its checksum computation must be modified for use over IPv6, to include the 128-bit IPv6 addresses instead of 32-bit IPv4 addresses.

* Source address – the one in the IPv6 header

* Destination address – the final destination; if the IPv6 packet doesn't contain a Routing header, TCP uses the destination address in the IPv6 header, otherwise, at the originating node, it uses the address in the last element of the Routing header, and, at the receiving node, it uses the destination address in the IPv6 header.

Martian packet - IPv6 Martian IPv6 packets include Bogon filtering|bogons and those having source or destination addresses with the following special-use prefixes:RFC Special-Use IPv6 Addresses

Martian packet - IPv6 6to4 is an IPv6#Transition mechanisms|IPv6 transition technology where the IPv6 address encodes the originating IPv4 address such that every IPv4 /32 has a corresponding, unique IPv6 /48 prefix. Because 6to4 relays use the encoded value for determining the end site of the 6to4 tunnel, 6to4 addresses corresponding to IPv4 martians are not routable and should never appear on the public internet. The 6to4 martians are as follows:

Martian packet - IPv6 However, the Teredo tunneling#IPv6 addressing|encoding format encodes the Teredo server address and tunnel information before the IPv4 client address

Classless network - IPv6 CIDR blocks
The standard subnet size for IPv6 networks is a /64 block, which is required for the operation of IPv6#Stateless address autoconfiguration (SLAAC)|stateless address autoconfiguration.RFC 4862 At first, the IETF recommended in RFC 3177 as a best practice that all end sites receive a /48 address allocation,RFC 3177, IAB/IESG Recommendation on IPv6 Address Allocations to Sites, IAB/IESG (September 2001) however, criticism and reevaluation of actual needs and practices has led to more flexible allocation recommendations in RFC 6177 RFC 6177, IPv6 Address Assignment to End Sites, T

List of IPv6 tunnel brokers
The columns in the table provide the following details:

List of IPv6 tunnel brokers - Implementations
There are a variety of tunnel brokers that provide their own implementations based on different business goals. Listed here are the common implementations as used by the listed IPv6 tunnel brokers.

List of IPv6 tunnel brokers - Gogo6 gogoSERVER
gogoSERVER (formerly Gateway6) is used by the Freenet6 service, which is the first IPv6 tunnel broker service, going into production in It was started as a project of Viagenie and then Hexago was spun off as a commercial company selling Gateway6, which powered Freenet6, as their flagship product. In June 2009, Hexago became gogo6 through a management buyout and the Freenet6 service became part of gogoNET, a social network for IPv6 professionals.[ What is gogoNET?]

List of IPv6 tunnel brokers - SixXS sixxsd
SixXS's [ sixxsd] is what powers all the SixXS PoPs. It is a purpose built software for the purpose of tunneling at high performance and low latency. Development started in 2002[ SixXS History] and has evolved into the current v4 version of the software.

List of IPv6 tunnel brokers - CITC ddtb
[ CITC Tunnel Broker], run by the Saudi Arabia IPv6 Task Force, uses their own implementation of the TSP RFC named 'ddtb'.

World IPv6 Day and World IPv6 Launch Day
'World IPv6 Day' was a technical testing and publicity event in 2011 sponsored and organized by the Internet Society and several large content providers to test and promote public IPv6 deployment.; archived on 23 June 2011 [ here] by Webcite

World IPv6 Day and World IPv6 Launch Day
Following the success of the 2011 test day, the Internet Society carried out a 'World IPv6 Launch' day on June 6, 2012 which, instead of testing, planned to bring permanent IPv6 deployment for the products and services of the participants.[ Internet Society: World IPv6 Launch on June 6, 2012, To Bring Permanent IPv6 Deployment]

World IPv6 Day and World IPv6 Launch Day - World IPv6 Day
An additional goal was to motivate organizations across the industry – Internet service providers, hardware makers, Operating System vendors and web companies – to prepare their services for IPv6, so as to ensure a successful transition from IPv4 as address space runs out.

The test primarily consisted of websites publishing AAAA records, which allow IPv6 capable hosts to connect using IPv6. Although Internet service providers (ISP) have been encouraged to participate, they were not expected to deploy anything active on that day, just increase their readiness to handle support issues. The concept was widely discussed at the 2010 Google IPv6 Conference.

Many companies and organizations participated in the experiment, including the largest search engines, social networking websites and Internet backbone content distribution networks.

World IPv6 Day and World IPv6 Launch Day - Participants
Participants in the World IPv6 Launch included participants from the 2011 test day, and many more, including the Wikimedia Foundation, which permanently enabled IPv6 on its sites, including Wikipedia.

World IPv6 Day and World IPv6 Launch Day - Results
Major carriers measured the percentage of IPv6 traffic of all Internet traffic as increasing from to with respect to native and tunneled stacks combined.

Most IPv6 traffic in consumer access networks was to Google sites. Demonstrating the need for content sites to adopt IPv6 for success, the biggest increase was actually in 6to4 transitional technologies.

Early results indicated that the day passed according to plan and without significant problems for the participants.

Cisco and Google reported no significant issues during the test.

But the consensus was that more work needed to be done before IPv6 could consistently be applied.Dornan, Andy (16 June 2011) [ What Did IPv6 Day Teach Us?] Information Week; archived on 20 June 2011 [ here] by WebciteMacVittie, Lori (11 June 2011) [ IPv4 to IPv6 switch: When protocols collide] ZD Net; archived 20 June 2011 [ here] by WebCite

The participants will continue to perform detailed analyses of the data. Many participants find it worthwhile to continue to maintain dual-stacks.[ Dual Stack Connectivity Chart] RIPE Network Coordination Centre; the version on 23 June 2011 was archived [ here] by WebCite

World IPv6 Day and World IPv6 Launch Day - World IPv6 Launch
Following the success of the original World IPv6 Day, the exercise was repeated on June 6, 2012 as the World IPv6 Launch, this time with the intention of leaving IPv6 permanently enabled on all participating sites. The event was billed as this time, it's for real.

According to Alain Fiocco of Cisco, content that currently receives roughly 30% of global World Wide Web IPv4 pageviews should now have become available via IPv6 after World IPv6 Launch Day. IPv6 traffic on AMS-IX rose by 50% on the launch day, from 2 Gbit/s to 3 Gbit/s. IPv6 traffic on AMS-IX was measured by ether type distribution as 0.4 percent, while IPv4 was measured as 99.6 percent on average in both daily and weekly graphs.

World IPv6 Day and World IPv6 Launch Day - Trivia
The launch began at 00:00 Coordinated Universal Time|UTC, which notably coincided with the Transit_of_Venus,_2012|2012 Transit of Venus.

DoD IPv6 Product Certification
Once products are certified for special interoperability, they are added to the [ DoD's Unified Capabilities Approved Products List (UC APL) for IPv6]

DoD IPv6 Product Certification
According to Kris Strance, DoD CIO IPv6 Lead, [ The testing of IPv6 is a part of all product evaluations — it is much broader in scope now.] The [ UC APL] is now a single consolidated list of products that have completed Interoperability (IO) and Information Assurance (IA) certification.

DoD IPv6 Product Certification - DoD's IPv6 Standards
[ The DoD IPv6 Standards Profiles for IPv6 Capable Products (DoD IPv6 Profile)] is the singular “IPv6 Capable” definition in DoD. It is a document that lists the six agreed upon product classes (Host, Router, Layer 3 Switch, Network Appliance, Security Device, and Advanced Server) and their corresponding standards (RFCs). It lists each standard according to its level of requirement:

* MUST: The standard is required to be implemented in the product now.

* SHOULD: The standard is optional, but recommended for implementation.

* SHOULD+: The standard is optional now, but will be required within a short period of time.

DoD IPv6 Product Certification - DoD's IPv6 Generic Test Plan
The JITC uses its publicly available [ IPv6 Generic Test Plan (GTP)] to test each product for its conformance, performance and interoperability of IPv6 according to the DoD IPv6 Profile. The JITC uses a combination of automated testing tools and manual functional test procedures to conduct this testing.

DoD IPv6 Product Certification - The Process
# The vendor, or Program Manager, must make their intentions known to test by providing the JITC with a Letter of Compliance (LoC). This letter will consist of the product to test, the product class it belongs to, a listing of all of the standards that it implements, and a signature from a Vice President or officer of the company. This is the “gateway” to the testing process.

# Approximately 6 weeks before the start of testing, the vendor must provide the JITC with funding. This funding must be in the form of a check. The amount is only to charge direct labor hours for testing by the contractor labor support.

# If the product successfully meets the criteria, it will be entered on the DoD's UC APL for IPv6.

DoD IPv6 Product Certification - IPv6 Pre-Certification Testing Advocates
There are many companies and organizations that help develop and test products for vendors prior to testing at the JITC. These organizations cannot grant certification, but can conduct pre-testing to ensure a vendor's product will pass the necessary certification. Below is a list of these organizations:

DoD IPv6 Product Certification - IPv6 Pre-Certification Testing Advocates
* The University of New Hampshire InterOperability Laboratory - IPv6 Ready Logo testing: [

DoD IPv6 Product Certification - The IPv6 Ready Logo Program
The IPv6 Forum has a service called IPv6 Ready Logo. This service represents a qualification program that assures devices have been tested and are IPv6 capable. Once certified, the service grants qualified products to display their logo. In the IPv6 Forum, they present objectives that are to:

• Verify protocol implementation and validate interoperability of IPv6 products.

IPv6 experts suggest only pursuing to purchase devices given the Phase-2 approval or gold logo since they are given the full treatment:

The Department of Defense (DoD) is committed to IPv6 and will likely be the first federal organization completely converted to IPv6. They also have a process for qualifying IPv6 equipment.

The task of certifying IPv6 products was given to the Joint Interoperability Test Command (JITC), part of the Defense Information Systems Agency (DISA). To help standardize IPv6 qualification procedures, the JITC follows what’s called the IPv6 Generic Test Plan.

After JITC qualifies a product, it is added to the Unified Capabilities Approved Products List. Fortunately, JITC makes the list available to the public.

IP fragmentation - IPv4 and IPv6 differences
Though the header formats are different for IPv4 and IPv6, analogous fields are used for fragmentation, so the algorithm can be reused for fragmentation and reassembly.

IP fragmentation - IPv4 and IPv6 differences
In IPv6, this minimum capability is increased to 1280 bytes,RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, Steve Deering|S

IPv6 transition mechanisms
'IPv6 transition mechanisms' are technologies that facilitate the IPv6 deployment|transitioning of the Internet from its initial (and current) IPv4 infrastructure to the successor addressing and routing system of IPv6|Internet Protocol Version 6 (IPv6). As IPv4 and IPv6 networks are not directly interoperable, these technologies are designed to permit hosts on either network to participate in networking with the other network.

IPv6 transition mechanisms
To meet its technical criteria, IPv6 must have a straightforward transition plan from the current IPv4.RFC IPng Technical Criteria The Internet Engineering Task Force (IETF) conducts working groups and discussions through the IETF Internet Drafts and Requests for Comments processes to develop these transition technologies towards that goal. Some basic IPv6 transition mechanisms are defined in RFC 4213.

IPv6 transition mechanisms - Stateless IP/ICMP Translation
They have the prefix ::ffff:0:0:0/96 and may be written as ::ffff:0:a.b.c.d, in which the IPv4 formatted address a.b.c.d refers to an IPv6-enabled node

The algorithm can be used in a solution that allows IPv6 hosts, that do not have a permanently assigned IPv4 address, to communicate with IPv4-only hosts. Address assignment and routing details are not addressed by the specification. SIIT can be viewed as a special case of stateless network address translation.

The specification is a product of the NGTRANS IETF working group, and was initially drafted in February 2000 as RFC 2765 by E. Nordmark of Sun Microsystems. RFC 2765 was obsoleted by RFC 6145 in 2011.RFC 6145 IP/ICMP Translation Algorithm The address format part of RFC 2765 is defined in RFC 6052.RFC IPv6 Addressing of IPv4/IPv6 Translators The framework of IPv4/IPv6 translation is defined in RFC 6144.RFC Framework for IPv4/IPv6 Translation

IPv6 transition mechanisms - Tunnel broker
A Tunnel broker combines several IPv6 Transition Mechanisms and enables users to actively use them.

The primary transition mechanism provided by a tunnel broker is IPv6 in IPv4 tunneling, usually with the help of 6in4, Tunnel Setup Protocol|TSP or AYIYA tunnels.

The first tunnel brokers were demonstrated in February 1999.RFC:3053

IPv6 transition mechanisms - 6rd
6rd is a mechanism to facilitate rapid deployment of the IPv6 service across IPv4 infrastructures of Internet service providers (Internet service provider|ISPs). It uses stateless address mappings between IPv4 and IPv6 addresses, and transmits IPv6 packets across automatic tunnels that follow the same optimized routes between customer nodes as IPv4 packets.

It has been used for the first large deployment of an IPv6 service with native addresses at the end of 2007 (RFC 5569 RFC 5569 IPv6 Rapid Deployment on IPv4 Infrastructures (6rd)).

The standard-track specification of the protocol is in RFC 5969.RFC 5969 IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol Specification

IPv6 transition mechanisms - Transport Relay Translation
RFC 3142 defines the 'Transport Relay Translation' ('TRT') method. This is the most common form of NAT-PT/NAPT-PT but relies on DNS translation between AAAA and A records known as DNS-ALG as defined in RFC 2694.

IPv6 transition mechanisms - NAT64
The NAT64 server then creates a Network address translation|NAT-mapping between the IPv6 and the IPv4 address, allowing them to communicate.RFC 6146 Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers

IPv6 transition mechanisms - DNS64
The standard-track specification of DNS64 is in RFC 6147.RFC 6147 DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers

There are two noticeable issues with this transition mechanism:

*It only works for cases where DNS is used to find the remote host address, if IPv4 literals are used the DNS64 server will never be involved.

*Because the DNS64 server needs to return records not specified by the domain owner, DNSSEC validation against the DNSSEC#Deployment at the DNS root|root will fail in cases where the DNS server doing the translation is not the domain owner's server.

IPv6 transition mechanisms - 464XLAT
464XLAT (RFC 6877) allows clients on IPv6-only networks to access IPv4-only Internet services, such as Skype.

Skype client software) into IPv6 to send (over an IPv6-only network) to a NAT64 translator (see above) which translates them back into IPv4 to send (over an IPv4-capable network) to an IPv4-only server (e.g

There is a CLAT implementation for Android, [ Android CLAT]. T-Mobile USA provides NAT64 with T-Mobile's IPv6-only service.

IPv6 transition mechanisms - Dual-Stack Lite (DS-Lite)
Because of IPv4 address exhaustion, 'Dual-Stack Lite' (RFC 6333) was designed to let an Internet service provider omit the deployment of any IPv4 address to the customer's Customer-premises equipment (CPE). Instead, only global IPv6 addresses are provided. (Regular Dual-Stack deploys global addresses for both IPv4 and IPv6.)

IPv6 transition mechanisms - Dual-Stack Lite (DS-Lite)
The CGN uniquely identifies traffic flows by recording the CPE public IPv6 address, the private IPv4 address, and TCP or UDP port number as a session.RFC Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion

IPv6 transition mechanisms - Draft proposals
These mechanisms are still being discussed or have been abandoned by the IETF.

4rd is a mechanism to facilitate residual deployment of the IPv4 service across IPv6 networks. Like 6rd, it uses stateless address mappings between IPv6 and IPv4. It supports an extension of IPv4 address based on transport-layer ports. This is similar to Address plus Port|A+P, but with each customer having a port set of up to 4 port ranges, and with port sets algorithmically derived from customer IPv6 prefixes.

IPv6 transition mechanisms - MAP
Mapping of Address and Port (MAP) is a Cisco IPv6 transition proposal which combines A+P port address translation with tunneling of the IPv4 packets over an ISP provider's internal IPv6 network. . MAP has standards-track Internet Draft status.

IPv6 transition mechanisms - NAT-PT
Network Address Translation/Protocol Translation (or simply 'NAT-PT') is defined in RFC 2766 but due to numerous problems, it has been obsoleted by RFC 4966 and deprecated to historic status. It is typically used in conjunction with a Domain Name System|DNS application-level gateway (DNS-ALG) implementation.

IPv6 transition mechanisms - NAPT-PT
While almost identical to NAT-PT, Network Address Port Translation + Protocol Translation which is also described in RFC 2766 adds translation of the ports as well as the address. This is done primarily to avoid two hosts on one side of the mechanism from using the same exposed port on the other side of the mechanism, which could cause application instability and/or security flaws.

IPv6 transition mechanisms - Implementations
*stone (software), port translator for Windows Unix-based systems.

*[ Jool], an implementation for Linux of RFC6146 (stateful NAT64), developed by Monterrey Institute of Technology and Higher Education|Monterrey Institute of Technology (ITESM) and NIC Mexico

*[ TAYGA], a stateless NAT64 implementation for Linux

*[ naptd], user-level NAT-PT

*[ Address Family Transition Router], a DS-Lite implementation

*[ IVI] ([ second page])

*Microsoft Forefront Unified Access Gateway, a reverse proxy and VPN solution that implements DNS64 and NAT64

Site Multihoming by IPv6 Intermediation
The 'Site Multihoming by IPv6 Intermediation' ('SHIM6') protocol is an Internet Layer shim (computing)|shim defined in RFC 5533.

Site Multihoming by IPv6 Intermediation - Architecture
The SHIM6 architecture defines failure detection and locator pair exploration functions. The first is used to detect outages through the path defined by the current locator pair for a communication. To achieve this, hints provided by upper protocols such as Transmission Control Protocol (TCP) are used, or specific SHIM6 packet probes. The second function is used to determine valid locator pairs that could be used when an outage is detected.

The ability to change locators while a communication is being held introduces security problems, so mechanisms based on applying cryptography to the address generation process (Cryptographically Generated Addresses, CGA), or on bounding the addresses to the prefixes assigned to a host through hash-based addresses were defined. These approaches are not needed for IPv4 because of the short address length (32 bits).

An implementation of shim6 in the Linux kernel called [ LinShim6] is now available.

Mobile IPv6 'Mobile IP' (or 'IP mobility') is an Internet Engineering Task Force (IETF) standard communications Protocol (computing)|protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address. Mobile IP for IPv4 is described in IETF RFC 5944, and extensions are defined in IETF RFC 'Mobile IPv6', the IP mobility implementation for the next generation of the Internet Protocol, IPv6, is described in RFC 6275.

Mobile IPv6 - Introduction
The Mobile IP protocol allows location-independent routing of IP datagrams on the Internet

Mobile IPv6 - Applications
In many applications (e.g., VPN, VoIP), sudden changes in network connectivity and IP address can cause problems.

Mobile IP was designed to support seamless and continuous Internet connectivity.

Mobile IP is most often found in wired and wireless environments where users need to carry their mobile devices across multiple LAN subnets. Examples of use are in roaming between overlapping wireless systems, e.g., IP over Digital Video Broadcasting|DVB, Wireless LAN|WLAN, WiMAX and Broadband wireless access|BWA.

Mobile IP is not required within cellular systems such as 3G, to provide transparency when Internet users migrate between cellular towers, since these systems provide their own data link layer handover and roaming mechanisms. However, it is often used in 3G systems to allow seamless IP mobility between different packet data serving node (PDSN) domains.

Mobile IPv6 - Operational principles
The goal of IP Mobility is to maintain the TCP connection between a mobile host and a static host while reducing the effects of location changes while the mobile host is moving around, without having to change the underlying TCP/IP protocol. To solve the problem, the RFC allows for a kind of proxy agent to act as a middle-man between a mobile host and a correpondent host.

* A home agent (HA) stores information about mobile nodes whose permanent home address is in the home agent's network. The HA acts as a router on a MH’s home network which tunnels datagrams for delivery to the MH when it is away from home, maintains a location directory (LD) for the MH.

* A foreign agent (FA) stores information about mobile nodes visiting its network

The so called Care of Address is a termination point of a tunnel toward a MH, for datagrams forwarded to the MH while it is away from home.

Mobile Nodes (MN) are responsible for discovering whether it is connected to its home network or has moved to a foreign network

A node wanting to communicate with the mobile node uses the permanent home address of the mobile node as the destination address to send packets to

In Mobile IPv6 (MIPv6), reverse tunneling is the default behaviour, with RO being an optional behaviour.

Mobile IPv6 - Performance
A performance evaluation of Mobile IPv6, carried out by NEC|NEC Europe, can be found at the ACM Digital Library, under the entry [ A simulation study on the performance of mobile IPv6 in a WLAN-based cellular network], from the Elsevier Computer Networks Journal (CNJ), special issue on The New Internet Architecture, September 2002.

Mobile IPv6 - Performance
Additionally, a performance comparison between Mobile IPv6 and some of its proposed enhancements (Hierarchical Mobile IPv6, Fast Handovers for Mobile IPv6 and their Combination) is available under the entry [ A performance comparison of Mobile IPv6, Hierarchical Mobile IPv6, fast handovers for Mobile IPv6 and their combination], from the ACM SIGMOBILE Mobile Computing and Communications Review (MC2R), Volume 7, Issue 4, October, 2003.

Mobile IPv6 - Development
[ A Simulation Study on the Performance of Hierarchical Mobile IPv6] In Proceedings of the International Teletraffic Congress (ITC), Berlin, Germany, August 2003

HMIPv6 explanation can be found at [ Hierarchical-Mobile-IPv6].

Researchers create support for mobile networking without requiring any pre-deployed infrastructure as it currently is required by MIP. One such example is [ Interactive Protocol for Mobile Networking (IPMN)] which promises supporting mobility on a regular IP network just from the network edges by intelligent signalling between IP at end-points and application layer module with improved quality of service.

The protocol is an extension of Mobile IPv6 and allows session continuity for every node in the Mobile Network as the network moves.

Mobile IPv6 - Changes in IPv6 for Mobile IPv6
*A set of mobility options to include in mobility messages

*A new Type 2 Routing header

*Changes to router discovery messages and options and additional Neighbor Discovery options

Mobile IPv6 - Definition of terms
;: A home agent is a router (computing)|router on a mobile node’s home network which tunnels datagrams for delivery to the mobile node when it is away from home. It maintains current location (IP address) information for the mobile node. It is used with one or more foreign agents.

Mobile IPv6 - Definition of terms
;: A foreign agent is a router that stores information about mobile nodes visiting its network. Foreign agents also advertise care-of-addresses which are used by Mobile IP.

Reverse DNS lookup - IPv6 reverse resolution
Reverse DNS lookups for IPv6 addresses use the special domain ip6.arpa. An IPv6 address appears as a name in this domain as a sequence of nibbles in reverse order, represented as hexadecimal digits as subdomains. For example, the pointer domain name corresponding to the IPv6 address 2001:db8::567:89ab is b.a b.d ip6.arpa.

IPv6 stateless address autoconfiguration
'Internet Protocol version 6' ('IPv6') is the latest revision of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion.

IPv6 stateless address autoconfiguration - Technical overview
Network security was a design requirement of the IPv6 architecture, and included the original specification of IPsec.

IPv6 stateless address autoconfiguration - IPv4
IPv4|Internet Protocol Version 4 (IPv4) was the first publicly used version of the Internet Protocol

IPv6 stateless address autoconfiguration - IPv4
The last unassigned top-level address blocks of 16 million IPv4 addresses were allocated in February 2011 by the Internet Assigned Numbers Authority (IANA) to the five Regional Internet registry|regional Internet registries (RIRs)

IPv6 stateless address autoconfiguration - Working-group proposals
By the beginning of 1992, several proposals appeared for an expanded Internet addressing system and by the end of 1992 the IETF announced a call for white papers.RFC 1550, IP: Next Generation (IPng) White Paper Solicitation, S

IPv6 stateless address autoconfiguration - Working-group proposals
The Internet Engineering Task Force adopted the IPng model on 25 July 1994, with the formation of several IPng working groups. By 1996, a series of Request for comments|RFCs was released defining Internet Protocol version 6 (IPv6), starting with RFC (Version 5 was used by the experimental Internet Stream Protocol.)

IPv6 stateless address autoconfiguration - Comparison with IPv4
Most transport and application-layer protocols need little or no change to operate over IPv6; exceptions are application protocols that embed internet-layer addresses, such as File Transfer Protocol|FTP and Network Time Protocol|NTPv3, where the new address format may cause conflicts with existing protocol syntax.

IPv6 stateless address autoconfiguration - Larger address space
Thus, actual address space utilization rates will be small in IPv6, but network management and routing efficiency is improved by the large subnet space and hierarchical route aggregation.

IPv6 stateless address autoconfiguration - Larger address space
Berkowitz (January 1997) 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.RFC 4862, IPv6 Stateless Address Autoconfiguration, S

IPv6 stateless address autoconfiguration - Multicasting
IPv6 also provides for new multicast implementations, including embedding rendezvous point addresses in an IPv6 multicast group address, which simplifies the deployment of inter-domain solutions.RFC 3956, Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address, P

IPv6 stateless address autoconfiguration - Multicasting
Thus each user of an IPv6 subnet automatically has available a set of globally routable source-specific multicast groups for multicast applications.RFC 3306, Unicast-Prefix-based IPv6 Multicast Addresses, B

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