Internet Protocol version 6 (IPv6) is the most recent version of the
Internet Protocol
The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.
IP h ...
(IP), the
communications protocol
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchr ...
that provides an identification and location system for computers on networks and routes traffic across the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
. IPv6 was developed by the
Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and a ...
(IETF) to deal with the long-anticipated problem of
IPv4 address exhaustion
IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 billion addresses available, depletion has been anticipated since the late 1980s, when the Interne ...
, and is intended to replace
IPv4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version de ...
.
In December 1998, IPv6 became a Draft Standard for the IETF,
which subsequently ratified it as an
Internet Standard
In computer network engineering, an Internet Standard is a normative specification of a technology or methodology applicable to the Internet. Internet Standards are created and published by the Internet Engineering Task Force (IETF). They allow ...
on 14 July 2017.
Devices on the Internet are assigned a unique
IP address
An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...
for identification and location definition. With the rapid growth of the Internet after commercialization in the 1990s, it became evident that far more addresses would be needed to connect devices than the IPv4 address space had available. By 1998, the IETF had formalized the successor protocol. IPv6 uses 128-
bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...
addresses, theoretically allowing 2
128, or approximately total addresses. The actual number is slightly smaller, as multiple ranges are reserved for special use or completely excluded from use. The two protocols are not designed to be
interoperable
Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader def ...
, and thus direct communication between them is impossible, complicating the move to IPv6. However, several
transition mechanisms have been devised to rectify this.
IPv6 provides other technical benefits in addition to a larger addressing space. In particular, it permits hierarchical address allocation methods that facilitate
route aggregation
A supernetwork, or supernet, is an Internet Protocol (IP) network that is formed by aggregation of multiple networks (or subnets) into a larger network. The new routing prefix for the aggregate network represents the constituent networks in a ...
across the Internet, and thus limit the expansion of
routing table
In computer networking, a routing table, or routing information base (RIB), is a data table stored in a router or a network host that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with tho ...
s. The use of multicast addressing is expanded and simplified, and provides additional optimization for the delivery of services. Device mobility, security, and configuration aspects have been considered in the design of the protocol.
IPv6 addresses are represented as eight groups of four
hexadecimal
In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexa ...
digits each, separated by colons. The full representation may be shortened; for example, ''2001:0db8:0000:0000:0000:8a2e:0370:7334'' becomes ''2001:db8::8a2e:370:7334''.
Main features
![IPv6 address terminology-en](https://upload.wikimedia.org/wikipedia/commons/5/5e/IPv6_address_terminology-en.svg)
IPv6 is an
Internet Layer
The internet layer is a group of internetworking methods, protocols, and specifications in the Internet protocol suite that are used to transport network packets from the originating host across network boundaries; if necessary, to the destinat ...
protocol for
packet-switched
In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the pac ...
internetworking
Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interc ...
and provides end-to-end
datagram
A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The del ...
transmission across multiple IP networks, closely adhering to the design principles developed in the previous version of the protocol,
Internet Protocol Version 4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version de ...
(IPv4).
In addition to offering more addresses, IPv6 also implements features not present in IPv4. It simplifies aspects of address configuration, network renumbering, and router announcements when changing network connectivity providers. It simplifies processing of packets in routers by placing the responsibility for packet fragmentation into the end points. The IPv6
subnet
A subnetwork or subnet is a logical subdivision of an IP network. Updated by RFC 6918. The practice of dividing a network into two or more networks is called subnetting.
Computers that belong to the same subnet are addressed with an identical ...
size is standardized by fixing the size of the host identifier portion of an address to 64 bits.
The addressing architecture of IPv6 is defined in and allows three different types of transmission:
unicast
Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication.
In computer networking, unicast is a one-to-one transmission from one point in ...
,
anycast
Anycast is a network addressing and routing methodology in which a single destination IP address is shared by devices (generally servers) in multiple locations. Routers direct packets addressed to this destination to the location nearest the sen ...
and
multicast
In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...
.
Motivation and origin
IPv4 address exhaustion
Internet Protocol Version 4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version de ...
(IPv4) was the first publicly used version of the
Internet Protocol
The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.
IP h ...
. IPv4 was developed as a research project by the
Defense Advanced Research Projects Agency
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military.
Originally known as the Adv ...
(DARPA), a
United States Department of Defense
The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secu ...
agency, before becoming the foundation for the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
and the
World Wide Web
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.
Documents and downloadable media are made available to the network through web se ...
. IPv4 includes an addressing system that uses numerical identifiers consisting of 32 bits. These addresses are typically displayed in
dot-decimal notation
Dot-decimal notation is a presentation format for numerical data. It consists of a string of decimal numbers, using the full stop (''dot'') as a separation character.
A common use of dot-decimal notation is in information technology where it is ...
as decimal values of four octets, each in the range 0 to 255, or 8 bits per number. Thus, IPv4 provides an addressing capability of 2
32 or approximately 4.3 billion addresses. Address exhaustion was not initially a concern in IPv4 as this version was originally presumed to be a test of DARPA's networking concepts. During the first decade of operation of the Internet, 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
IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 billion addresses available, depletion has been anticipated since the late 1980s, when the Interne ...
, and that further changes to the Internet infrastructure were needed.
The last unassigned top-level address blocks of 16 million IPv4 addresses were allocated in February 2011 by the
Internet Assigned Numbers Authority
The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Interne ...
(IANA) to the five
regional Internet registries
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
...
(RIRs). However, each RIR still has available address pools and is expected to continue with standard address allocation policies until one
Classless Inter-Domain Routing
Classless Inter-Domain Routing (CIDR ) is a method for allocating IP addresses and for IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. Its g ...
(CIDR) block remains. After that, only blocks of 1,024 addresses (/22) will be provided from the RIRs to a
local Internet registry
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
...
(LIR). As of September 2015, all of
Asia-Pacific Network Information Centre
APNIC (the Asia Pacific Network Information Centre) is the regional Internet address registry ( RIR) for the Asia-Pacific region. It is one of the world's five RIRs and is part of the Number Resource Organization ( NRO).
APNIC provides numb ...
(APNIC), the
Réseaux IP Européens Network Coordination Centre (RIPE_NCC),
Latin America and Caribbean Network Information Centre (LACNIC), and
American Registry for Internet Numbers
The American Registry for Internet Numbers (ARIN) is the regional Internet registry for Canada, the United States, and many Caribbean and North Atlantic islands. ARIN manages the distribution of Internet number resources, including IPv4 and IP ...
(ARIN) have reached this stage. This leaves
African Network Information Center (AFRINIC) as the sole regional internet registry that is still using the normal protocol for distributing IPv4 addresses. As of November 2018, AFRINIC's minimum allocation is or 1024 IPv4 addresses. A
LIR
Lir or Ler (meaning "Sea" in Old Irish; ''Ler'' and ''Lir'' are the nominative and genitive forms, respectively) is a sea god in Irish mythology. His name suggests that he is a personification of the sea, rather than a distinct deity. He is na ...
may receive additional allocation when about 80% of all the address space has been utilized.
RIPE NCC announced that it had fully run out of IPv4 addresses on 25 November 2019, and called for greater progress on the adoption of IPv6.
It is widely expected that the Internet will use IPv4 alongside IPv6 for the foreseeable future.
Comparison with IPv4
On the Internet, data is transmitted in the form of
network packet
In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the ''payload''. Control informa ...
s. IPv6 specifies a new
packet format, designed to minimize packet header processing by routers.
[ Obsoletes RFC 1883.] Because the headers of IPv4 packets and IPv6 packets are significantly different, the two protocols are not interoperable. However, 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
The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data ...
(FTP) and
Network Time Protocol (NTP), where the new address format may cause conflicts with existing protocol syntax.
Larger address space
The main advantage of IPv6 over IPv4 is its larger address space. The size of an IPv6 address is 128 bits, compared to 32 bits in IPv4.
[ The address space therefore has 2128=340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (approximately ). Some blocks of this space and some specific addresses are reserved for special uses.
While this address space is very large, it was not the intent of the designers of IPv6 to assure geographical saturation with usable addresses. Rather, the longer addresses simplify allocation of addresses, enable efficient ]route aggregation
A supernetwork, or supernet, is an Internet Protocol (IP) network that is formed by aggregation of multiple networks (or subnets) into a larger network. The new routing prefix for the aggregate network represents the constituent networks in a ...
, and allow implementation of special addressing features. In IPv4, complex Classless Inter-Domain Routing
Classless Inter-Domain Routing (CIDR ) is a method for allocating IP addresses and for IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. Its g ...
(CIDR) methods were developed to make the best use of the small address space. The standard size of a subnet in IPv6 is 264 addresses, about four billion times the size of the entire IPv4 address space. Thus, actual address space utilization will be small in IPv6, but network management and routing efficiency are improved by the large subnet space and hierarchical route aggregation.
Multicasting
Multicast
In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...
ing, the transmission of a packet to multiple destinations in a single send operation, is part of the base specification in IPv6. In IPv4 this is an optional (although commonly implemented) feature.[, ''Host extensions for IP multicasting'', S. Deering (August 1989)] IPv6 multicast addressing has features and protocols in common with IPv4 multicast, but also provides changes and improvements by eliminating the need for certain protocols. IPv6 does not implement traditional IP broadcast, i.e. the transmission of a packet to all hosts on the attached link using a special ''broadcast address'', and therefore does not define broadcast addresses. In IPv6, the same result is achieved by sending a packet to the link-local ''all nodes'' multicast group at address ff02::1, which is analogous to IPv4 multicasting to address 224.0.0.1. 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.[, ''Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address'', P. Savola, B. Haberman (November 2004)]
In IPv4 it is very difficult for an organization to get even one globally routable multicast group assignment, and the implementation of inter-domain solutions is arcane. Unicast address assignments by a local Internet registry
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
...
for IPv6 have at least a 64-bit routing prefix, yielding the smallest subnet size available in IPv6 (also 64 bits). With such an assignment it is possible to embed the unicast address prefix into the IPv6 multicast address format, while still providing a 32-bit block, the least significant bits of the address, or approximately 4.2 billion multicast group identifiers. Thus each user of an IPv6 subnet automatically has available a set of globally routable source-specific multicast groups for multicast applications.
Stateless address autoconfiguration (SLAAC)
IPv6 hosts configure themselves automatically. Every interface has a self-generated link-local address and, when connected to a network, conflict resolution is performed and routers provide network prefixes via router advertisements.[ Stateless configuration of routers can be achieved with a special router renumbering protocol.][, ''Router Renumbering for IPv6'', M. Crawford, August 2000.] When necessary, hosts may configure additional stateful addresses via Dynamic Host Configuration Protocol version 6 (DHCPv6) or static addresses manually.
Like IPv4, IPv6 supports globally unique IP address
An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...
es. 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 by rendering network address translation obsolete. Therefore, every device on the network is globally addressable directly from any other device.
A stable, unique, globally addressable IP address would facilitate tracking a device across networks. Therefore, such addresses are a particular privacy concern for mobile devices, such as laptops and cell phones.
To address these privacy concerns, the SLAAC protocol includes what are typically called "privacy addresses" or, more correctly, "temporary addresses", codified in RFC 4941, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6". Temporary addresses are random and unstable. A typical consumer device generates a new temporary address daily and will ignore traffic addressed to an old address after one week. Temporary addresses are used by default by Windows since XP SP1, macOS since (Mac OS X) 10.7, Android since 4.0, and iOS since version 4.3. Use of temporary addresses by Linux distributions varies.
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.
The SLAAC address generation method is implementation-dependent. IETF recommends that addresses be deterministic but semantically opaque.
IPsec
Internet Protocol Security
In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in v ...
(IPsec) was originally developed for IPv6, but found widespread deployment first in IPv4, for which it was re-engineered. IPsec was a mandatory part of all IPv6 protocol implementations,[ and ]Internet Key Exchange
In computing, Internet Key Exchange (IKE, sometimes IKEv1 or IKEv2, depending on version) is the protocol used to set up a security association (SA) in the IPsec protocol suite. IKE builds upon the Oakley protocol and ISAKMP.The Internet Key Exch ...
(IKE) was recommended, but with RFC 6434 the inclusion of IPsec in IPv6 implementations was downgraded to a recommendation because it was considered impractical to require full IPsec implementation for all types of devices that may use IPv6. However, as of RFC 4301 IPv6 protocol implementations that do implement IPsec need to implement IKEv2 and need to support a minimum set of cryptographic algorithms
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...
. This requirement will help to make IPsec implementations more interoperable between devices from different vendors. The IPsec Authentication Header (AH) and the Encapsulating Security Payload header (ESP) are implemented as IPv6 extension headers.
Simplified processing by routers
The packet header in IPv6 is simpler than the IPv4 header. Many rarely used fields have been moved to optional header extensions. With the simplified IPv6 packet header the process of packet forwarding by routers has been simplified. Although IPv6 packet headers are at least twice the size of IPv4 packet headers, processing of packets that only contain the base IPv6 header by routers may, in some cases, be more efficient, because less processing is required in routers due to the headers being aligned to match common word sizes.[ However, many devices implement IPv6 support in software (as opposed to hardware), thus resulting in very bad packet processing performance. Additionally, for many implementations, the use of Extension Headers causes packets to be processed by a router's CPU, leading to poor performance or even security issues.]
Moreover, an IPv6 header does not include a checksum. The IPv4 header checksum
The Internet checksum, also called the IPv4 header checksum is a checksum used in version 4 of the Internet Protocol (IPv4) to detect corruption in the header of IPv4 packets. It is carried in the IP packet header, and represents the 16-bit resul ...
is calculated for the IPv4 header, and has to be recalculated by routers every time the time to live
Time to live (TTL) or hop limit is a mechanism which limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or times ...
(called hop limit
Time to live (TTL) or hop limit is a mechanism which limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or times ...
in the IPv6 protocol) is reduced by one. The absence of a checksum in the IPv6 header furthers the end-to-end principle
The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
of Internet design, which envisioned that most processing in the network occurs in the leaf nodes. Integrity protection for the data that is encapsulated in the IPv6 packet is assumed to be assured by both the link layer or error detection in higher-layer protocols, namely the Transmission Control Protocol
The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...
(TCP) and the User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. ...
(UDP) on the transport layer
In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end ...
. Thus, while IPv4 allowed UDP datagram headers to have no checksum (indicated by 0 in the header field), IPv6 requires a checksum in UDP headers.
IPv6 routers do not perform IP fragmentation
400px, An example of the fragmentation of a protocol data unit in a given layer into smaller fragments.
IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can ...
. IPv6 hosts are required either to perform path MTU discovery
Path MTU Discovery (PMTUD) is a standardized technique in computer networking for determining the maximum transmission unit (MTU) size on the network path between two Internet Protocol (IP) hosts, usually with the goal of avoiding IP fragmentat ...
, perform end-to-end fragmentation, or send packets no larger than the default maximum transmission unit
In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size tha ...
(MTU), which is 1280 octets.
Mobility
Unlike mobile IPv4, mobile IPv6
Mobile IP (or MIP) is an Internet Engineering Task Force (IETF) standard communications 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 desc ...
avoids triangular routing
Triangular routing is a method for transmitting packets of data in communications networks. It uses a form of routing that sends a packet to a proxy system before transmission to the intended destination. Triangular routing is a problem in mobile ...
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.[, ''Network Mobility (NEMO) Basic Protocol Support'', V. Devarapalli, R. Wakikawa, A. Petrescu, P. Thubert (January 2005)]
Extension headers
The IPv6 packet header has a minimum size of 40 octets (320 bits). Options are implemented as extensions. This provides the opportunity to extend the protocol in the future without affecting the core packet structure. However, RFC 7872 notes that some network operators drop IPv6 packets with extension headers when they traverse transit autonomous systems
An autonomous robot is a robot that acts without recourse to human control. The first autonomous robots environment were known as Elmer and Elsie, which were constructed in the late 1940s by W. Grey Walter. They were the first robots in history t ...
.
Jumbograms
IPv4 limits packets to 65,535 (216−1) octets of payload. An IPv6 node can optionally handle packets over this limit, referred to as jumbogram
In packet-switched computer networks, a jumbogram (portmanteau of ''jumbo'' and ''datagram'') is an internet-layer packet exceeding the standard maximum transmission unit (MTU) of the underlying network technology. In contrast, large packets f ...
s, which can be as large as 4,294,967,295 (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 extension header.[, ''IPv6 Jumbograms'', D. Borman, S. Deering, R. Hinden (August 1999)]
IPv6 packets
An IPv6 packet has two parts: a header and payload
Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...
.
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.
The fixed header occupies the first 40 octets (320 bits) of the IPv6 packet. It contains the source and destination addresses, traffic class, hop count, and the type of the optional extension or payload which follows the header. This ''Next Header'' field tells the receiver how to interpret the data which follows the header. If the packet contains options, this field contains the option type of the next option. The "Next Header" field of the last option points to the upper-layer protocol that is carried in the packet's payload
Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...
.
The current use of the IPv6 Traffic Class field divides this between a 6 bit Differentiated Services Code Point and a 2-bit Explicit Congestion Notification field.
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
In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in ...
framework.
Without special options, a payload must be less than . With a Jumbo Payload option (in a ''Hop-By-Hop Options'' extension header), the payload must be less than 4 GB.
Unlike with IPv4, routers never fragment a packet. Hosts are expected to use Path MTU Discovery
Path MTU Discovery (PMTUD) is a standardized technique in computer networking for determining the maximum transmission unit (MTU) size on the network path between two Internet Protocol (IP) hosts, usually with the goal of avoiding IP fragmentat ...
to make their packets small enough to reach the destination without needing to be fragmented. See IPv6 packet fragmentation.
Addressing
IPv6 address
An Internet Protocol Version 6 address (IPv6 address) is a numeric label that is used to identify and locate a network interface of a computer or a network node participating in a computer network using IPv6. IP addresses are included in the ...
es have 128 bits. The design of the IPv6 address space implements a different design philosophy than in IPv4, in which subnetting was used to improve the efficiency of utilization of the small address space. In IPv6, the address space is deemed large enough for the foreseeable future, and a local area subnet always uses 64 bits for the host portion of the address, designated as the interface identifier, while the most-significant 64 bits are used as the routing prefix. While the myth has existed regarding IPv6 subnets being impossible to scan, RFC 7707 notes that patterns resulting from some IPv6 address configuration techniques and algorithms allow address scanning in many real-world scenarios.
Address representation
The 128 bits of an IPv6 address are represented in 8 groups of 16 bits each. Each group is written as four hexadecimal digits (sometimes called ''hextet
In computing, a hextet, or a ''chomp'', is a sixteen-bit aggregation, or four nibbles. As a nibble typically is notated in hexadecimal format, a hextet consists of 4 hexadecimal digits. A hextet is the unofficial name for each of the 8 blocks in a ...
s'' or more formally '' hexadectets'' and informally a ''quibble'' or ''quad-nibble'') and the groups are separated by colons (:). An example of this representation is .
For convenience and clarity, the representation of an IPv6 address may be shortened with the following rules:
*One or more leading zeros from any group of hexadecimal digits are removed, which is usually done to all of the leading zeros. For example, the group is converted to .
*Consecutive sections of zeros are replaced with two colons (::). This may only be used once in an address, as multiple use would render the address indeterminate. requires that a double colon not be used to denote an omitted single section of zeros.
An example of application of these rules:
:Initial address: .
:After removing all leading zeros in each group: .
:After omitting consecutive sections of zeros: .
The loopback address is defined in and is abbreviated to 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.
Because IPv6 addresses contain colons, and URLs use colons to separate the host from the port number, RFC2732 specifies that an IPv6 address used as the host-part of a URL should be enclosed in square brackets, e.g. http:// 001:db8:4006:812::200e/nowiki> or http:// 001:db8:4006:812::200e8080/path/page.html.
Link-local address
All interfaces of IPv6 hosts require a link-local address
In computer networking, a link-local address is a unicast network address that is valid only for communications within the subnetwork that the host is connected to. Link-local addresses are most often assigned automatically with a process known a ...
, which have the prefix . This prefix is combined with a 64-bit suffix, which the host can compute and assign by itself without the presence or cooperation of an external network component like a DHCP server, in a process called ''link-local address autoconfiguration''.
The lower 64 bits of the link-local address (the suffix) were originally derived from the MAC address of the underlying network interface card. As this method of assigning addresses would cause undesirable address changes when faulty network cards were replaced, and as it also suffered from a number of security and privacy issues, RFC 8064 has replaced the original MAC-based method with the hash-based method specified in RFC 7217.
Address uniqueness and router solicitation
IPv6 uses a new mechanism for mapping IP addresses to link-layer addresses (e.g. MAC address
A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking techno ...
es), because it does not support the broadcast
Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum ( radio waves), in a one-to-many model. Broadcasting began ...
addressing method, on which the functionality of the Address Resolution Protocol
The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function ...
(ARP) in IPv4 is based. IPv6 implements the Neighbor Discovery Protocol
The Neighbor Discovery Protocol (NDP), or simply Neighbor Discovery (ND), is a protocol of the Internet protocol suite used with Internet Protocol Version 6 (IPv6). It operates at the link layer of the Internet model, and is responsible for gat ...
(NDP, ND) in the link layer, which relies on ICMPv6
Internet Control Message Protocol version 6 (ICMPv6) is the implementation of the Internet Control Message Protocol (ICMP) for Internet Protocol version 6 (IPv6). ICMPv6 is an integral part of IPv6 and performs error reporting and diagnostic fu ...
and multicast
In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...
transmission. IPv6 hosts verify the uniqueness of their IPv6 addresses in a local area network
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
(LAN) by sending a neighbor solicitation message asking for the link-layer address of the IP address. If any other host in the LAN is using that address, it responds.
A host bringing up a new IPv6 interface first generates a unique link-local address using one of several mechanisms designed to generate a unique address. Should a non-unique address be detected, the host can try again with a newly generated address. Once a unique link-local address is established, the IPv6 host determines whether the LAN is connected on this link to any router interface that supports IPv6. It does so by sending out an ICMPv6 router solicitation message to the all-routers multicast group with its link-local address as source. If there is no answer after a predetermined number of attempts, the host concludes that no routers are connected. If it does get a response, known as a router advertisement, from a router, the response includes the network configuration information to allow establishment of a globally unique address with an appropriate unicast network prefix. There are also two flag bits that tell the host whether it should use DHCP to get further information and addresses:
*The Manage bit, which indicates whether or not the host should use DHCP to obtain additional addresses rather than rely on an auto-configured address from the router advertisement.
*The Other bit, which indicates whether or not the host should obtain other information through DHCP. The other information consists of one or more prefix information options for the subnets that the host is attached to, a lifetime for the prefix, and two flags:
**On-link: If this flag is set, the host will treat all addresses on the specific subnet as being on-link and send packets directly to them instead of sending them to a router for the duration of the given lifetime.
**Address: This flag tells the host to actually create a global address.
Global addressing
The assignment procedure for global addresses is similar to local-address construction. The prefix is supplied from router advertisements on the network. Multiple prefix announcements cause multiple addresses to be configured.
Stateless address autoconfiguration (SLAAC) requires a address block, as defined in . Local Internet registries
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
...
are assigned at least blocks, which they divide among subordinate networks. The initial recommendation stated assignment of a subnet to end-consumer sites (). This was replaced by , which "recommends giving home sites significantly more than a single , but does not recommend that every home site be given a either". s are specifically considered. It remains to be seen whether ISPs will honor this recommendation. For example, during initial trials, Comcast
Comcast Corporation (formerly known as American Cable Systems and Comcast Holdings),Before the AT&T merger in 2001, the parent company was Comcast Holdings Corporation. Comcast Holdings Corporation now refers to a subsidiary of Comcast Corpora ...
customers were given a single network.
IPv6 in the Domain Name System
In the Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...
(DNS), hostname
In computer networking, a hostname (archaically nodename) is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication, such as the World Wide Web. Hos ...
s are mapped to IPv6 addresses by AAAA ("quad-A") resource records. For reverse resolution, the IETF reserved the domain ip6.arpa, where the name space is hierarchically divided by the 1-digit hexadecimal
In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexa ...
representation of nibble units (4 bits) of the IPv6 address. This scheme is defined in .
When a dual-stack host queries a DNS server to resolve a fully qualified domain name
A fully qualified domain name (FQDN), sometimes also referred to as an ''absolute domain name'', is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS). It specifies all domain levels, including th ...
(FQDN), the DNS client of the host sends two DNS requests, one querying A records and the other querying AAAA records. The host operating system may be configured with a preference for address selection rules .
An alternate record type was used in early DNS implementations for IPv6, designed to facilitate network renumbering, the ''A6'' records for the forward lookup and a number of other innovations such as ''bit-string labels'' and '' DNAME'' records. It is defined in and its references (with further discussion of the pros and cons of both schemes in ), but has been deprecated to experimental status ().
Transition mechanisms
IPv6 is not foreseen to supplant IPv4 instantaneously. Both protocols will continue to operate simultaneously for some time. Therefore, IPv6 transition mechanism
An IPv6 transition mechanism is a technology that facilitates the transitioning of the Internet from the Internet Protocol version 4 (IPv4) infrastructure in use since 1983 to the successor addressing and routing system of Internet Protocol Vers ...
s are needed to enable IPv6 hosts to reach IPv4 services and to allow isolated IPv6 hosts and networks to reach each other over IPv4 infrastructure.
According to Silvia Hagen, a dual-stack implementation of the IPv4 and IPv6 on devices is the easiest way to migrate to IPv6. Many other transition mechanisms use tunneling to encapsulate IPv6 traffic within IPv4 networks and vice versa. This is an imperfect solution, which reduces the maximum transmission unit
In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size tha ...
(MTU) of a link and therefore complicates Path MTU Discovery
Path MTU Discovery (PMTUD) is a standardized technique in computer networking for determining the maximum transmission unit (MTU) size on the network path between two Internet Protocol (IP) hosts, usually with the goal of avoiding IP fragmentat ...
, and may increase latency.
Dual-stack IP implementation
Dual-stack IP implementations provide complete IPv4 and IPv6 protocol stacks in the operating system of a computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
or network device
Networking hardware, also known as network equipment or computer networking devices, are electronic devices which are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in ...
on top of the common physical layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip.
The ...
implementation, such as Ethernet
Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
. This permits dual-stack hosts to participate in IPv6 and IPv4 networks simultaneously. The method is defined in .
A device with dual-stack implementation in the operating system has an IPv4 and IPv6 address, and can communicate with other nodes in the LAN or the Internet using either IPv4 or IPv6. The Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...
(DNS) protocol is used by both IP protocols to resolve fully qualified domain name
A fully qualified domain name (FQDN), sometimes also referred to as an ''absolute domain name'', is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS). It specifies all domain levels, including th ...
s (FQDN) and IP addresses, but dual stack requires that the resolving DNS server can resolve both types of addresses. Such a dual stack DNS server would hold IPv4 addresses in the A records, and IPv6 addresses in the AAAA records. Depending on the destination that is to be resolved, a DNS name server may return an IPv4 or IPv6 IP address, or both. A default address selection mechanism, or preferred protocol, needs to be configured either on hosts or the DNS server. The IETF
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and a ...
has published Happy Eyeballs
Happy Eyeballs (also called Fast Fallback) is an algorithm published by the IETF that makes dual-stack applications (those that understand both IPv4 and IPv6) more responsive to users by attempting to connect using both IPv4 and IPv6 at the same ...
to assist dual stack applications, so that they can connect using both IPv4 and IPv6, but prefer an IPv6 connection if it is available. However, dual-stack also needs to be implemented on all routers between the host and the service for which the DNS server has returned an IPv6 address. Dual-stack clients should only be configured to prefer IPv6, if the network is able to forward IPv6 packets using the IPv6 versions of routing protocols
A routing protocol specifies how routers communicate with each other to distribute information that enables them to select routes between nodes on a computer network. Routers perform the traffic directing functions on the Internet; data packets ...
. When dual stack networks protocols are in place the application layer
An application layer is an abstraction layer that specifies the shared communications protocols and Interface (computing), interface methods used by Host (network), hosts in a communications network. An ''application layer'' abstraction is speci ...
can be migrated to IPv6.
While dual-stack is supported by major operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
and network device
Networking hardware, also known as network equipment or computer networking devices, are electronic devices which are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in ...
vendors, legacy networking hardware and servers don't support IPv6.
ISP customers with public-facing IPv6
Internet service providers
An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privatel ...
(ISPs) are increasingly providing their business and private customers with public-facing IPv6 global unicast addresses. If IPv4 is still used in the local area network (LAN), however, and the ISP can only provide one public-facing IPv6 address, the IPv4 LAN addresses are translated into the public facing IPv6 address using NAT64
NAT64 is an IPv6 transition mechanism that facilitates communication between IPv6 and IPv4 hosts by using a form of network address translation (NAT). The NAT64 gateway is a translator between IPv4 and IPv6 protocols, for which function it need ...
, a network address translation (NAT) mechanism. Some ISPs cannot provide their customers with public-facing IPv4 and IPv6 addresses, thus supporting dual-stack networking, because some ISPs have exhausted their globally routable IPv4 address pool. Meanwhile, ISP customers are still trying to reach IPv4 web servers
A web server is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates ...
and other destinations.
A significant percentage of ISPs in all regional Internet registry
A regional Internet registry (RIR) is an organization that manages the allocation and registration of Internet number resources within a region of the world. Internet number resources include IP addresses and autonomous system (AS) numbers.
...
(RIR) zones have obtained IPv6 address space. This includes many of the world's major ISPs and mobile network
A cellular network or mobile network is a communication network where the link to and from end nodes is wireless. The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver (typically thre ...
operators, such as Verizon Wireless
Verizon is an American wireless network operator that previously operated as a separate division of Verizon Communications under the name Verizon Wireless. In a 2019 reorganization, Verizon moved the wireless products and services into the div ...
, StarHub Cable, Chubu Telecommunications, Kabel Deutschland
Vodafone Kabel Deutschland GmbH is the largest cable television operator in Germany. Kabel Deutschland was subject to a hostile takeover bid by the British Vodafone Group in September 2013; the deal was approved in December 2013 and finalised on ...
, Swisscom, T-Mobile
T-Mobile is the brand name used by some of the mobile communications subsidiaries of the German telecommunications company Deutsche Telekom AG in the Czech Republic (T-Mobile Czech Republic), Poland (T-Mobile Polska), the United States (T-Mobile ...
, Internode and Telefónica
Telefónica, S.A. () is a Spanish multinational telecommunications company headquartered in Madrid, Spain. It is one of the largest telephone operators and mobile network providers in the world. It provides fixed and mobile telephony, broadba ...
.
While some ISPs still allocate customers only IPv4 addresses, many ISPs allocate their customers only an IPv6 or dual-stack IPv4 and IPv6. ISPs report the share of IPv6 traffic from customers over their network to be anything between 20% and 40%, but by mid-2017 IPv6 traffic still only accounted for a fraction of total traffic at several large Internet exchange point
Internet exchange points (IXes or IXPs) are common grounds of IP networking, allowing participant Internet service providers (ISPs) to exchange data destined for their respective networks. IXPs are generally located at places with preexisting ...
s (IXPs). AMS-IX reported it to be 2% and SeattleIX reported 7%. A 2017 survey found that many DSL customers that were served by a dual stack ISP did not request DNS servers to resolve fully qualified domain names into IPv6 addresses. The survey also found that the majority of traffic from IPv6-ready web-server resources were still requested and served over IPv4, mostly due to ISP customers that did not use the dual stack facility provided by their ISP and to a lesser extent due to customers of IPv4-only ISPs.
Tunneling
The technical basis for tunneling, or encapsulating IPv6 packets in IPv4 packets, is outlined in RFC 4213. When the Internet backbone was IPv4-only, one of the frequently used tunneling protocols was 6to4
6to4 is an Internet transition mechanism for migrating from Internet Protocol version 4 (IPv4) to version 6 (IPv6) and a system that allows IPv6 packets to be transmitted over an IPv4 network (generally the IPv4 Internet) without the need to co ...
. Teredo tunneling
In computer networking, Teredo is a transition technology that gives full IPv6 connectivity for IPv6-capable hosts that are on the IPv4 Internet but have no native connection to an IPv6 network. Unlike similar protocols such as 6to4, it can perf ...
was also frequently used for integrating IPv6 LANs with the IPv4 Internet backbone. Teredo is outlined in RFC 4380 and allows IPv6 local area networks
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
to tunnel over IPv4 networks, by encapsulating IPv6 packets within UDP. The Teredo relay is an IPv6 router that mediates between a Teredo server and the native IPv6 network. It was expected that 6to4 and Teredo would be widely deployed until ISP networks would switch to native IPv6, but by 2014 Google Statistics showed that the use of both mechanisms had dropped to almost 0.
IPv4-mapped IPv6 addresses
Hybrid dual-stack IPv6/IPv4 implementations recognize a special class of addresses, the IPv4-mapped IPv6 addresses.[ Table 20.] These addresses are typically written with a 96-bit prefix in the standard IPv6 format, and the remaining 32 bits are written in the customary dot-decimal notation
Dot-decimal notation is a presentation format for numerical data. It consists of a string of decimal numbers, using the full stop (''dot'') as a separation character.
A common use of dot-decimal notation is in information technology where it is ...
of IPv4.
Addresses in this group consist of an 80-bit prefix of zeros, the next 16 bits are ones, and the remaining, least-significant 32 bits contain the IPv4 address. For example, represents the IPv4 address . A previous format, called "IPv4-compatible IPv6 address", was ; however, this method is deprecated.
Because of the significant internal differences between IPv4 and IPv6 protocol stacks, some of the lower-level functionality available to programmers in the IPv6 stack does not work the same when used with IPv4-mapped addresses. Some common IPv6 stacks do not implement the IPv4-mapped address feature, either because the IPv6 and IPv4 stacks are separate implementations (e.g., Microsoft Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
2000, XP, and Server 2003), or because of security concerns (OpenBSD
OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...
). On these operating systems, a program must open a separate socket for each IP protocol it uses. On some systems, e.g., the Linux kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
, NetBSD
NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...
, and FreeBSD
FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...
, this feature is controlled by the socket option IPV6_V6ONLY.
The address prefix is a class of IPv4-embedded IPv6 addresses for use in NAT64
NAT64 is an IPv6 transition mechanism that facilitates communication between IPv6 and IPv4 hosts by using a form of network address translation (NAT). The NAT64 gateway is a translator between IPv4 and IPv6 protocols, for which function it need ...
transition methods. For example, represents the IPv4 address .
Security
A number of security implications may arise from the use of IPv6. Some of them may be related with the IPv6 protocols themselves, while others may be related with implementation flaws.
Shadow networks
The addition of nodes having IPv6 enabled by default by the software manufacturer, may result in the inadvertent creation of ''shadow networks'', causing IPv6 traffic flowing into networks having only IPv4 security management in place. This may also occur with operating system upgrades, when the newer operating system enables IPv6 by default, while the older one did not. Failing to update the security infrastructure to accommodate IPv6 can lead to IPv6 traffic bypassing it. Shadow networks have occurred on business networks in which enterprises are replacing Windows XP
Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...
systems that do not have an IPv6 stack enabled by default, with Windows 7
Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on July 22, 2009, and became generally available on October 22, 2009. It is the successor to Windows Vista, released nearly ...
systems, that do. Some IPv6 stack implementors have therefore recommended disabling IPv4 mapped addresses and instead using a dual-stack network where supporting both IPv4 and IPv6 is necessary.
IPv6 packet fragmentation
Research has shown that the use of fragmentation can be leveraged to evade network security controls, similar to IPv4. As a result, requires that the first fragment of an IPv6 packet contains the entire IPv6 header chain, such that some very pathological fragmentation cases are forbidden. Additionally, as a result of research on the evasion of RA-Guard in , has deprecated the use of fragmentation with Neighbor Discovery, and discouraged the use of fragmentation with Secure Neighbor Discovery (SEND).
Standardization through RFCs
Working-group proposals
A timeline for the standards governing IPv6
Due to the anticipated global growth of the Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
, the Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and a ...
(IETF) in the early 1990s started an effort to develop a next generation IP protocol. 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. In September 1993, the IETF created a temporary, ad hoc ''IP Next Generation'' (IPng) area to deal specifically with such issues. The new area was led by Allison Mankin
Allison Mankin is an American computer scientist and prominent figure in the area of Internet governance. She previously served as the Internet Research Task Force (IRTF) Chair and holds numerous leadership positions within the Internet Engineerin ...
and Scott Bradner, and had a directorate with 15 engineers from diverse backgrounds for direction-setting and preliminary document review:[ The working-group members were ]J. Allard
J Allard (born James Allard, on January 12, 1969 in Glens Falls, New York) is the chief executive officer of Project 529, a company that builds software for cyclists and law enforcement. Prior to starting Project 529, Allard was chief technology ...
(Microsoft), Steve Bellovin
Steven M. Bellovin is a researcher on computer networking and security. He has been a professor in the Computer Science department at Columbia University since 2005. Previously, Bellovin was a Fellow at AT&T Labs Research in Florham Park, New Jer ...
(AT&T), Jim Bound (Digital Equipment Corporation), Ross Callon (Wellfleet), Brian Carpenter (CERN), Dave Clark (MIT), John Curran (NEARNET), Steve Deering (Xerox), Dino Farinacci (Cisco), Paul Francis (NTT), Eric Fleischmann (Boeing), Mark Knopper (Ameritech), Greg Minshall (Novell), Rob Ullmann (Lotus), and Lixia Zhang
Lixia Zhang () is the Jonathan B. Postel Professor of Computer Science at the University of California, Los Angeles.. Her expertise is in computer networks; she helped found the Internet Engineering Task Force, designed the Resource Reservation ...
(Xerox).
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 . (Version 5 was used by the experimental ]Internet Stream Protocol
The Internet Stream Protocol (ST) is a family of experimental protocols first defined in Internet Experiment Note IEN-119 in 1979, and later substantially revised in RFC 1190 (ST-II) and RFC 1819 (ST2+).
The protocol uses the version number 5 in ...
.)
RFC standardization
The first RFC to standardize IPv6 was the in 1995, which became obsoleted by in 1998. In July 2017 this RFC was superseded by , which elevated IPv6 to "Internet Standard" (the highest maturity level for IETF protocols).[ Obsoletes RFC 2460.]
Deployment
The 1993 introduction of Classless Inter-Domain Routing
Classless Inter-Domain Routing (CIDR ) is a method for allocating IP addresses and for IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. Its g ...
(CIDR) in the routing and IP address allocation for the Internet, and the extensive use of network address translation (NAT), delayed IPv4 address exhaustion
IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 billion addresses available, depletion has been anticipated since the late 1980s, when the Interne ...
to allow for IPv6 deployment, which began in the mid-2000s.
Universities were among the early adopters of IPv6. Virginia Tech
Virginia Tech (formally the Virginia Polytechnic Institute and State University and informally VT, or VPI) is a Public university, public Land-grant college, land-grant research university with its main campus in Blacksburg, Virginia. It also ...
deployed IPv6 at a trial location in 2004 and later expanded IPv6 deployment across the campus network
A campus network, campus area network, corporate area network or CAN is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. The networking equipments (switches, routers) and transm ...
. By 2016, 82% of the traffic on their network used IPv6. Imperial College London
Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a cu ...
began experimental IPv6 deployment in 2003 and by 2016 the IPv6 traffic on their networks averaged between 20% and 40%. A significant portion of this IPv6 traffic was generated through their high energy physics
Particle physics or high energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standa ...
collaboration with CERN
The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...
, which relies entirely on IPv6.
The Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...
(DNS) has supported IPv6 since 2008. In the same year, IPv6 was first used in a major world event during the Beijing 2008 Summer Olympics
The 2008 Summer Olympics (), officially the Games of the XXIX Olympiad () and also known as Beijing 2008 (), were an international multisport event held from 8 to 24 August 2008, in Beijing, China. A total of 10,942 athletes from 204 Na ...
.
By 2011, all major operating systems in use on personal computers and server systems had production-quality IPv6 implementations. Cellular telephone systems presented a large deployment field for Internet Protocol devices as mobile telephone service made the transition from 3G to 4G technologies, in which voice is provisioned as a voice over IP
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of speech, voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms In ...
(VoIP) service that would leverage IPv6 enhancements. In 2009, the US cellular operator Verizon
Verizon Communications Inc., commonly known as Verizon, is an American multinational telecommunications conglomerate and a corporate component of the Dow Jones Industrial Average. The company is headquartered at 1095 Avenue of the Americas in ...
released technical specifications for devices to operate on its "next-generation" networks. The specification mandated IPv6 operation according to the ''3GPP Release 8 Specifications (March 2009)'', and deprecated IPv4 as an optional capability.
The deployment of IPv6 in the Internet backbone
The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer networks and core routers of the Internet. These data routes are hosted by commercial, government, academic and other high-ca ...
continued. In 2018 only 25.3% of the about 54,000 autonomous systems advertised both IPv4 and IPv6 prefixes in the global Border Gateway Protocol
Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet. BGP is classified as a path-vector routing protocol, and it makes ...
(BGP) routing database. A further 243 networks advertised only an IPv6 prefix. Internet backbone transit networks offering IPv6 support existed in every country globally, except in parts of Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, the Middle East
The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...
and China. By mid-2018 some major European broadband
In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...
ISPs had deployed IPv6 for the majority of their customers. Sky UK
Sky UK Limited is a British broadcaster and telecommunications company that provides television and broadband Internet services, fixed line and mobile telephone services to consumers and businesses in the United Kingdom. It is a subsidiary of ...
provided over 86% of its customers with IPv6, Deutsche Telekom
Deutsche Telekom AG (; short form often just Telekom, DTAG or DT; stylised as ·T·) is a German telecommunications company that is headquartered in Bonn and is the largest telecommunications provider in Europe by revenue. Deutsche Telekom was ...
had 56% deployment of IPv6, XS4ALL in the Netherlands had 73% deployment and in Belgium the broadband ISPs VOO
VOO (/vuː/) is the commercial name of the Belgian cable company, created by the Economic Interest Group ( EIG) of Brutélé GIE in (Brussels Region and Charleroi Region) and Association Liégeoise d'Electricité (A.L.E.- Télédis), currentl ...
and Telenet
Telenet was an American commercial packet-switched network which went into service in 1975. It was the first FCC-licensed public data network in the United States. Various commercial and government interests paid monthly fees for dedicated lines ...
had 73% and 63% IPv6 deployment respectively. In the United States the broadband ISP Comcast
Comcast Corporation (formerly known as American Cable Systems and Comcast Holdings),Before the AT&T merger in 2001, the parent company was Comcast Holdings Corporation. Comcast Holdings Corporation now refers to a subsidiary of Comcast Corpora ...
had an IPv6 deployment of about 66%. In 2018 Comcast reported an estimated 36.1 million IPv6 users, while AT&T
AT&T Inc. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile tel ...
reported 22.3 million IPv6 users.
See also
*China Next Generation Internet
The China Next Generation Internet (CNGI) () project is an ongoing plan for the accelerated rollout and application of the IPv6 protocol nationwide.
An author from the China Academy of Information and Communications Technology (CAICT) summarized ...
*Comparison of IPv6 support in operating systems
This is a comparison of operating systems in regard to their support of the IPv6 protocol.
Notes
*Operating systems that support neither DHCPv6 nor SLAAC cannot automatically configure unicast IPv6 addresses.
*Operating systems that support neit ...
*Comparison of IPv6 support in common applications
This is a comparison of applications in regard to their support of the IPv6
Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and locatio ...
*DoD IPv6 product certification
The United States Department of Defense, Department of Defense (DoD) Internet Protocol version 6 (IPv6) product certification program began as a mandate from the DoD's Assistant Secretary of Defense for Networks & Information Integration (ASD-NII) ...
*University of New Hampshire InterOperability Laboratory
The University of New Hampshire InterOperability Laboratory (UNH-IOL) is an independent test facility that provides interoperability and standards conformance testing for networking, telecommunications, data storage, and consumer technology produ ...
References
External links
IPv6 in the Linux Kernel
by Rami Rosen
An Introduction and Statistics about IPv6
by Google
The standard document ratifying IPv6
– RFC 8200 document ratifying IPv6 as an Internet Standard
{{Authority control
IPv6
Computer-related introductions in 1996
Internet layer protocols
Network layer protocols