Parts of this article (those related to RFC 8200 and RFC 8201) need to beupdated. Please help update this article to reflect recent events or newly available information.(July 2017)
Internet Protocol version 6 (IPv6) is the most recent version of theInternet Protocol (IP), thecommunications protocol that provides an identification and location system for computers on networks and routes traffic across theInternet. IPv6 was developed by theInternet Engineering Task Force (IETF) to deal with the long-anticipated problem ofIPv4 address exhaustion, and was intended to replaceIPv4.[1] In December 1998, IPv6 became a Draft Standard for the IETF,[2] which subsequently ratified it as anInternet Standard on 14 July 2017.[3][4]
Devices on the Internet are assigned a uniqueIP address 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 4,294,967,296 (232) IPv4 address space had available. By 1998, the IETF had formalized the successor protocol, IPv6 which uses 128-bit addresses, theoretically allowing 2128, or 340,282,366,920,938,463,463,374,607,431,768,211,456 total addresses. The actual number is slightly smaller, as multiple ranges are reserved for special usage or completely excluded from general use. The two protocols are not designed to beinteroperable, and thus direct communication between them is impossible, complicating the move to IPv6. However, severaltransition 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 facilitateroute aggregation across the Internet, and thus limit the expansion ofrouting tables. 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 fourhexadecimal digits each, separated by colons. The full representation may be shortened according to specific rules; for example,2001:0db8:0000:0000:0000:8a2e:0370:7334 becomes2001:db8::8a2e:370:7334.
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 packet processing in routers by placing the responsibility for packet fragmentation in the end points. The IPv6subnet size is standardized by fixing the size of the host identifier portion of an address to 64 bits.
Decomposition of the dot-decimalIPv4 address representation to its binary notation
Internet Protocol Version 4 (IPv4) was the first publicly used version of theInternet Protocol. IPv4 was developed as a research project by theDefense Advanced Research Projects Agency (DARPA), aUnited States Department of Defenseagency, before becoming the foundation for theInternet and theWorld Wide Web. IPv4 includes an addressing system that uses numerical identifiers consisting of 32 bits. These addresses are typically displayed indot-decimal notation 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 232 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.[7] 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 aclassless network model, it became clear that this would not suffice to preventIPv4 address exhaustion, and that further changes to the Internet infrastructure were needed.[8]
On the Internet, data is transmitted in the form ofnetwork packets. IPv6 specifies a newpacket format, designed to minimize packet header processing by routers.[2][15] 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 asFile Transfer Protocol (FTP) andNetwork Time Protocol (NTP), where the new address format may cause conflicts with existing protocol syntax.
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.[2] The address space therefore has 2128=340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (340undecillion, approximately3.4×1038). Some blocks of this space and some specific addresses arereserved 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 efficientroute aggregation, and allow implementation of special addressing features. In IPv4, complexClassless Inter-Domain Routing (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, 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.[16] 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 traditionalIP broadcast, i.e. the transmission of a packet to all hosts on the attached link using a specialbroadcast address, and therefore does not define broadcast addresses. In IPv6, the same result is achieved by sending a packet to the link-localall nodes multicast group at addressff02::1, which is analogous to IPv4 multicasting to address224.0.0.1. 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.[17]
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.[18] Unicast address assignments by alocal Internet registry 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.[19]
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.[20] Stateless configuration of routers can be achieved with a special router renumbering protocol.[21] When necessary, hosts may configure additional stateful addresses viaDynamic Host Configuration Protocol version 6 (DHCPv6) or static addresses manually.
Like IPv4, IPv6 supports globally uniqueIP addresses. 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 renderingnetwork 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.[22] To address these privacy concerns, the SLAAC protocol includes what are typically called "privacy addresses" or, more correctly, "temporary addresses".[23] 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,[24] 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.[25]
Renumbering an existing network for a new connectivity provider with different routing prefixes is a major effort with IPv4.[26][27] 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.[20]
The SLAAC address generation method is implementation-dependent. IETF recommends that addresses be deterministic but semantically opaque.[28]
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 part of all IPv6 protocol implementations,[2] andInternet Key Exchange (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.[29] However, as of RFC 4301 IPv6 protocol implementations that do implement IPsec need to implement IKEv2 and need to support a minimum set ofcryptographic algorithms. 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.[30]
The packet header in IPv6 is simpler than the IPv4 header. Many rarely used fields have been moved to optional header extensions. The IPv6 packet header has simplified the process of packet forwarding byrouters. 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 commonword sizes.[2][15] However, many devices implement IPv6 support in software (as opposed to hardware), thus resulting in very bad packet processing performance.[31] 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.[32]
Moreover, an IPv6 header does not include a checksum. TheIPv4 header checksum is calculated for the IPv4 header, and has to be recalculated by routers every time thetime to live (calledhop limit in the IPv6 protocol) is reduced by one. The absence of a checksum in the IPv6 header furthers theend-to-end principle 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 thelink layer or error detection in higher-layer protocols, namely theTransmission Control Protocol (TCP) and theUser Datagram Protocol (UDP) on thetransport layer. 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.
Unlike mobile IPv4,mobile IPv6 avoidstriangular 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.[33]
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.[2] However, RFC 7872 notes that some network operators drop IPv6 packets with extension headers when they traverse transitautonomous systems.
IPv4 limits packets to 65,535(216 − 1) octets of payload. An IPv6 node can optionally handle packets over this limit, referred to asjumbograms, 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.[34]
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. ThisNext 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'spayload.
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 theIPsec framework.
Without special options, a payload must be less than64kB. With a Jumbo Payload option (in aHop-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 usePath MTU Discovery to make their packets small enough to reach the destination without needing to be fragmented. SeeIPv6 packet fragmentation.
IPv6 addresses 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.[5]: 9 While the myth has existed regarding IPv6 subnets being impossible to scan,RFC7707 notes that patterns resulting from some IPv6 address configuration techniques and algorithms allow address scanning in many real-world scenarios.
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 calledhextets[37][38] or more formallyhexadectets[39] and informally aquibble orquad-nibble[39]) and the groups are separated by colons (:). An example of this representation is2001:0db8:0000:0000:0000:ff00:0042:8329.
For convenience and clarity, the representation of an IPv6 address may be shortened with the following rules:
One or moreleading zeros from any group of hexadecimal digits are removed, which is usually done to all of the leading zeros. For example, the group0042 is converted to42. The group0000 is converted to0.
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. A double colon should not be used to denote an omitted single section of zeros.[40]: §4.2.2
Because IPv6 addresses contain colons, and URLs use colons to separate the host from the port number, an IPv6 address used as the host-part of a URL should be enclosed in square brackets,[42] e.g. http://[2001:db8:4006:812::200e] or http://[2001:db8:4006:812::200e]:8080/path/page.html.
All interfaces of IPv6 hosts require alink-local address, which have the prefixfe80::/10. This prefix is followed by 54 bits that can be used for subnetting, although they are typically set to zeros, and a 64-bit interface identifier. The host can compute and assign the Interface identifier by itself without the presence or cooperation of an external network component like a DHCP server, in a process calledlink-local address autoconfiguration.[citation needed]
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,RFC8064 has replaced the original MAC-based method with the hash-based method specified inRFC7217.[citation needed]
IPv6 uses a new mechanism for mapping IP addresses to link-layer addresses (e.g.MAC addresses), because it does not support thebroadcast addressing method, on which the functionality of theAddress Resolution Protocol (ARP) in IPv4 is based. IPv6 implements theNeighbor Discovery Protocol (NDP, ND) in thelink layer, which relies onICMPv6 andmulticast transmission.[6]: 210 IPv6 hosts verify the uniqueness of their IPv6 addresses in alocal area network (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.[43]
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 anyrouter interface that supports IPv6. It does so by sending out an ICMPv6 router solicitation message to the all-routers[44] 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.[45] 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:[43]
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.
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.[43]
Stateless address autoconfiguration (SLAAC) requires a/64 address block.[5]Local Internet registries are assigned at least/32 blocks, which they divide among subordinate networks.[46] The initial recommendation of September 2001 stated assignment of a/48 subnet to end-consumer sites.[47] In March 2011 this recommendation was refined:[48] TheIETF "recommends giving home sites significantly more than a single/64, but does not recommend that every home site be given a/48 either". Blocks of/56s are specifically considered. It remains to be seen whether ISPs will honor this recommendation. For example, during initial trials,Comcast customers were given a single/64 network.[49]
When a dual-stack host queries a DNS server to resolve afully qualified domain name (FQDN), the DNS client of the host sends two DNS requests, one querying AAAA records and the other querying A records, in that order, by default. If both types of addresses are returned by the DNS, and there is a route for it, the IPv6 address is preferred over the IPv4 address. However, the host operating system may be configured with an alternate preference for address selection.[51][52]
An alternative record type was used in early DNS implementations for IPv6, designed to facilitate network renumbering. TheA6 resource record was used for the forward lookup, completed with a number of other innovations such asbit-string labels andDNAME records.[53] After a discussion of the pros and cons of both schemes,[54]) the use of A6 resource records has been deprecated to experimental status.[55]
IPv6 is not foreseen to supplant IPv4 instantaneously. Both protocols will continue to operate simultaneously for some time. Therefore,IPv6 transition mechanisms 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.[56]
According toSilvia Hagen, a dual-stack implementation of the IPv4 and IPv6 on devices is the easiest way to migrate to IPv6.[57] Many other transition mechanisms use tunneling to encapsulate IPv6 traffic within IPv4 networks and vice versa. This is an imperfect solution, which reduces themaximum transmission unit (MTU) of a link and therefore complicatesPath MTU Discovery, and may increaselatency.[58][59]
Dual-stack IP implementations provide complete IPv4 and IPv6 protocol stacks in the operating system of acomputer ornetwork device on top of the commonphysical layer implementation, such asEthernet. This permits dual-stack hosts to participate in IPv6 and IPv4 networks simultaneously.[60]
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 DNS protocol is used by both IP protocols to resolve fully qualified domain names and IP addresses, but dual stack requires that the resolving DNS server can resolve both types of addresses. Such a dual-stack DNS server holds 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. TheIETF has publishedHappy Eyeballs 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 be configured to prefer IPv6 only if the network is able to forward IPv6 packets using the IPv6 versions ofrouting protocols. When dual-stack network protocols are in place theapplication layer can be migrated to IPv6.[61]
While dual-stack is supported by majoroperating system and network device vendors, legacy networking hardware and servers do not support IPv6.
IPv6 Prefix Assignment mechanism with IANA, RIRs, and ISPs
Internet service providers (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 usingNAT64, anetwork 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 IPv4web servers and other destinations.[62]
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 largeInternet exchange points (IXPs).AMS-IX reported it to be 2% andSeattleIX 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.[64]
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 was6to4.[65]Teredo tunneling was also frequently used for integrating IPv6 LANs with the IPv4 Internet backbone. Teredo is outlined in RFC 4380 and allows IPv6local area networks 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.[66]
Hybrid dual-stack IPv6/IPv4 implementations recognize a special class of addresses, the IPv4-mapped IPv6 addresses.[67]: §2.2.3 [5] These addresses are typically written with a 96-bit prefix in the standard IPv6 format, and the remaining 32 bits are written in the customarydot-decimal notation 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,::ffff:192.0.2.128 represents the IPv4 address192.0.2.128. A previous format, called "IPv4-compatible IPv6 address", was::192.0.2.128; however, this method is deprecated.[5]
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 2000, XP, and Server 2003), or because of security concerns (OpenBSD).[68] On these operating systems, a program must open a separate socket for each IP protocol it uses. On some systems, e.g., theLinux kernel,NetBSD, andFreeBSD, this feature is controlled by the socket option IPV6_V6ONLY.[69]: 22
The address prefix64:ff9b::/96 is a class of IPv4-embedded IPv6 addresses for use inNAT64 transition methods.[70] For example,64:ff9b::192.0.2.128 represents the IPv4 address192.0.2.128.
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.[71][72]
The addition of nodes having IPv6 enabled by default by the software manufacturer may result in the inadvertent creation ofshadow 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.[73] Shadow networks have occurred on business networks in which enterprises are replacingWindows XP systems that do not have an IPv6 stack enabled by default, withWindows 7 systems, that do.[74] 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.[75]
Research has shown that the use of fragmentation could be leveraged to evade network security controls, similar to IPv4. As a result, it is now required that the first fragment of an IPv6 packet contains the entire IPv6 header chain,[76] such that some very pathological fragmentation cases are forbidden. Additionally, as a result of research on the evasion of RA-Guard, the use of fragmentation is deprecated withNeighbor Discovery,[77] and discouraged withSecure Neighbor Discovery (SEND).[78]
Due to the anticipated global growth of theInternet, theInternet Engineering Task Force (IETF) in the early 1990s started an effort to develop a next generation IP protocol.[6]: 209 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.[79] In September 1993, the IETF created a temporary, ad hocIP Next Generation (IPng) area to deal specifically with such issues. The new area was led byAllison Mankin andScott Bradner, and had a directorate with 15 engineers from diverse backgrounds for direction-setting and preliminary document review:[8][80] The working-group members wereJ. Allard (Microsoft),Steve Bellovin (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), andLixia Zhang (Xerox).[81]
The Internet Engineering Task Force adopted the IPng model on 25 July 1994, with the formation of several IPng working groups.[8] By 1996, a series ofRFCs was released defining Internet Protocol version 6 (IPv6), starting withRFC1883. (Version 5 was used by the experimentalInternet Stream Protocol.)
The first RFC to standardize IPv6 was theRFC1883 in 1995.[82] In 1998RFC2460 became the RFC for IPv6.[6]: 209 In July 2017RFC 2460 was superseded byRFC8200, which elevated IPv6 to "Internet Standard" (the highest maturity level for IETF protocols).[3]
Universities were among the early adopters of IPv6.Virginia Tech deployed IPv6 at a trial location in 2004 and later expanded IPv6 deployment across thecampus network. By 2016, 82% of the traffic on their network used IPv6.Imperial College London 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 theirhigh energy physics collaboration withCERN, which relies entirely on IPv6.[83]
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 from3G to4G technologies, in which voice is provisioned as avoice over IP (VoIP) service that would leverage IPv6 enhancements. In 2009, the US cellular operatorVerizon released technical specifications for devices to operate on its "next-generation" networks.[86] The specification mandated IPv6 operation according to the3GPP Release 8 Specifications (March 2009), and deprecated IPv4 as an optional capability.[86]
The deployment of IPv6 in theInternet backbone continued. In 2018 only 25.3% of the about 54,000 autonomous systems advertised both IPv4 and IPv6 prefixes in the globalBorder Gateway Protocol (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 ofAfrica, theMiddle East and China.[87]: 6 By mid-2018 some major Europeanbroadband ISPs had deployed IPv6 for the majority of their customers.Sky UK provided over 86% of its customers with IPv6,Deutsche Telekom had 56% deployment of IPv6,XS4ALL in the Netherlands had 73% deployment and in Belgium the broadband ISPsVOO andTelenet had 73% and 63% IPv6 deployment respectively.[87]: 7 In the United States the broadband ISPXfinity had an IPv6 deployment of about 66%. In 2018 Xfinity reported an estimated 36.1 million IPv6 users, whileAT&T reported 22.3 million IPv6 users.[87]: 7–8
^E. Jankiewicz; J. Loughney; T. Narten (December 2011).IPv6 Node Requirements.Internet Engineering Task Force.doi:10.17487/RFC6434.ISSN2070-1721.RFC6434.Obsolete. p. 17. Obsoleted byRFC 8504. ObsoletesRFC 4294.Previously, IPv6 mandated implementation of IPsec and recommended the key management approach of IKE. This document updates that recommendation by making support of the IPsec Architecture RFC4301 a SHOULD for all IPv6 nodes.
^Silvia Hagen (2014).IPv6 Essentials: Integrating IPv6 into Your IPv4 Network (3rd ed.). Sebastopol, CA: O'Reilly Media. p. 196.ISBN978-1-4493-3526-7.OCLC881832733.
^abcNarten, T. (August 1999). "Neighbor discovery and stateless autoconfiguration in IPv6".IEEE Internet Computing.3 (4):54–62.doi:10.1109/4236.780961.
