Jump to content

IPv6: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Removed and and list.
IPv6 may be difficult due to the limited support
Line 1: Line 1:
{{IPstack}}
{{IPstack}}
'''Internet Protocol version 6''' ('''IPv6''') is a version of the [[Internet Protocol]] (IP) that is designed to succeed [[IPv4|Internet Protocol version 4]] (IPv4). The Internet operates by transferring data in small [[Packet (information technology)|packet]]s that are independently [[routing|routed]] across networks as specified by an international [[communications protocol]] known as the Internet Protocol. Each data packet contains two numeric addresses that are the packet's origin and destination devices. Since 1981, IPv4 has been the publicly used version of the Internet Protocol, and it is currently the foundation for most [[Internet]] communications. The Internet's growth has created a need for more addresses than IPv4 is capable of. IPv6 allows for vastly more numerical addresses, but [[IPv6 deployment|switching from IPv4 to IPv6]] may be a difficult process.
'''Internet Protocol version 6''' ('''IPv6''') is a version of the [[Internet Protocol]] (IP) that is designed to succeed [[IPv4|Internet Protocol version 4]] (IPv4). The Internet operates by transferring data in small [[Packet (information technology)|packet]]s that are independently [[routing|routed]] across networks as specified by an international [[communications protocol]] known as the Internet Protocol. Each data packet contains two numeric addresses that are the packet's origin and destination devices. Since 1981, IPv4 has been the publicly used version of the Internet Protocol, and it is currently the foundation for most [[Internet]] communications. The Internet's growth has created a need for more addresses than IPv4 is capable of. IPv6 allows for vastly more numerical addresses, but [[IPv6 deployment|switching from IPv4 to IPv6]] may be a difficult process due to the limit [[ISP]], [[hardware]] and [[operating system]] support.


IPv6 was developed by the [[Internet Engineering Task Force]] (IETF) to deal with the long-anticipated [[IPv4 address exhaustion]], and is described in [[Internet standard]] document RFC 2460, published in December 1998.<ref name=rfc2460>RFC 2460, ''Internet Protocol, Version 6 (IPv6) Specification'', [[Steve Deering|S. Deering]], R. Hinden (December 1998)</ref> Like IPv4, IPv6 is an [[Internet Layer]] protocol for [[packet-switched]] [[internetworking]] and provides end-to-end [[datagram]] transmission across multiple IP networks. While IPv4 allows 32 bits for an [[IP address|Internet Protocol address]], and can therefore support 2<sup>32</sup> (4,294,967,296) addresses, IPv6 uses 128-bit addresses, so the new address space supports 2<sup>128</sup> (approximately 340 [[undecillion]] or {{val|3.4|e=38}}) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for [[network address translation]] (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.
IPv6 was developed by the [[Internet Engineering Task Force]] (IETF) to deal with the long-anticipated [[IPv4 address exhaustion]], and is described in [[Internet standard]] document RFC 2460, published in December 1998.<ref name=rfc2460>RFC 2460, ''Internet Protocol, Version 6 (IPv6) Specification'', [[Steve Deering|S. Deering]], R. Hinden (December 1998)</ref> Like IPv4, IPv6 is an [[Internet Layer]] protocol for [[packet-switched]] [[internetworking]] and provides end-to-end [[datagram]] transmission across multiple IP networks. While IPv4 allows 32 bits for an [[IP address|Internet Protocol address]], and can therefore support 2<sup>32</sup> (4,294,967,296) addresses, IPv6 uses 128-bit addresses, so the new address space supports 2<sup>128</sup> (approximately 340 [[undecillion]] or {{val|3.4|e=38}}) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for [[network address translation]] (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.

Revision as of 15:39, 3 June 2011

Internet protocol suite
Application layer
Transport layer
Internet layer
Link layer

Internet Protocol version 6 (IPv6) is a version of the Internet Protocol (IP) that is designed to succeed Internet Protocol version 4 (IPv4). The Internet operates by transferring data in small packets that are independently routed across networks as specified by an international communications protocol known as the Internet Protocol. Each data packet contains two numeric addresses that are the packet's origin and destination devices. Since 1981, IPv4 has been the publicly used version of the Internet Protocol, and it is currently the foundation for most Internet communications. The Internet's growth has created a need for more addresses than IPv4 is capable of. IPv6 allows for vastly more numerical addresses, but switching from IPv4 to IPv6 may be a difficult process due to the limit ISP, hardware and operating system support.

IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated IPv4 address exhaustion, and is described in Internet standard document RFC 2460, published in December 1998.[1] Like IPv4, IPv6 is an Internet Layer protocol for packet-switched internetworking and provides end-to-end datagram transmission across multiple IP networks. While IPv4 allows 32 bits for an Internet Protocol address, and can therefore support 232 (4,294,967,296) addresses, IPv6 uses 128-bit addresses, so the new address space supports 2128 (approximately 340 undecillion or 3.4×1038) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.

IPv6 implements additional features not present in IPv4. It simplifies aspects of address assignment (stateless address autoconfiguration), network renumbering and router announcements when changing Internet connectivity providers. The IPv6 subnet size has been standardized by fixing the size of the host identifier portion of an address to 64 bits to facilitate an automatic mechanism for forming the host identifier from link layer media addressing information (MAC address). Network security is also integrated into the design of the IPv6 architecture, and the IPv6 specification mandates support for IPsec as a fundamental interoperability requirement.

The last top level (/8) block of free IPv4 addresses was assigned in February 2011, although many free addresses still remain in most assigned blocks and will continue to be allocated for some three to six months from then. After that, only 1024 addresses are made available from APNIC for each LIR.[2] While IPv6 is supported on all major operating systems in use in commercial, business, and home consumer environments,[3] IPv6 does not implement interoperability features with IPv4, and creates essentially a parallel, independent network. Exchanging traffic between the two networks requires special translator gateways, but modern computer operating systems implement dual-protocol software for transparent access to both networks using 'tunneling'. In December 2010, despite marking its 12th anniversary as a Standards Track protocol, IPv6 was only in its infancy in terms of general worldwide deployment. A 2008 study[4] by Google Inc. indicated that penetration was still less than one percent of Internet-enabled hosts in any country at that time.

Motivation and origins

IPv4

Main article: IPv4

The first publicly used version of the Internet Protocol, Version 4 (IPv4), provides an addressing capability of 232 or approximately 4.3 billion addresses. This was deemed sufficient in the early design stages of the Internet when the explosive growth and worldwide proliferation of networks were not anticipated.

During the first decade of operation of the Internet, by the late 1980s, it became apparent that methods had to be developed to conserve address space. In the early 1990s, even after the redesign of the addressing system using a classless network model, it became clear that this would not suffice to prevent IPv4 address exhaustion, and that further changes to the Internet infrastructure were needed.[5]

Working group proposal

By the beginning of 1992, several proposals appeared and by the end of 1992, the IETF announced a call for white papers[6] and the creation of the IP Next Generation (IPng) area of working groups.[5][7]

The Internet Engineering Task Force adopted the IPng model on July 25, 1994, with the formation of several IPng working groups.[5] By 1996, a series of RFCs was released defining Internet Protocol version 6 (IPv6), starting with RFC 1883. (Version 5 was used by the experimental Internet Stream Protocol.)

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

IPv4 exhaustion

Main article: IPv4 address exhaustion

On February 3, 2011, the last batch of 5 /8 address blocks were allocated to the Regional Internet Registries.[8] Each of the address blocks represents approximately 16.7 million possible addresses, or over 80 million combined potential addresses. These addresses could well be fully consumed within three to six months at current rates of allocation.[9]

In 2003, the director of Asia-Pacific Network Information Centre (APNIC), Paul Wilson, stated that, based on then-current rates of deployment, the available space would last for one or two decades.[10] In September 2005, a report by Cisco Systems suggested that the pool of available addresses would exhaust in as little as 4 to 5 years.[11] In 2008, a policy process started for the end-game and post-exhaustion era.[12] In 2010, a daily updated report projected the global address pool exhaustion by the first quarter of 2011, and depletion at the five regional Internet registries before the end of 2011.[13]

On February 3, 2011, in a ceremony in Miami, the Internet Assigned Numbers Authority (IANA) assigned the last five /8 allocation blocks of IPv4 addresses, officially depleting the global pool of completely fresh blocks of addresses.[14] APNIC was the first RIR to exhaust its regional pool on 15 April 2011, except for a small amount of address space reserved for the transition to IPv6, which will be allocated in a much more restricted way.[15]

Comparison to IPv4

IPv6 specifies a new packet format, designed to minimize packet header processing by routers.[1][16] Because the headers of IPv4 packets and IPv6 packets are significantly different, the two protocols are not interoperable. However, in most respects, IPv6 is a conservative extension of IPv4. Most transport and application-layer protocols need little or no change to operate over IPv6; exceptions are application protocols that embed internet-layer addresses, such as FTP and NTPv3.

Larger address space

Decomposition of an IPv6 address into its binary form

The most important feature of IPv6 is a much larger address space than in IPv4. The length of an IPv6 address is 128 bits, compared to 32 bits in IPv4.[1] The address space therefore supports 2128 or approximately 3.4×1038 addresses. By comparison, this amounts to approximately 5×1028 addresses for each of the 6.8 billion people alive in 2010.[17] (In addition, the IPv4 address space is poorly allocated, with approximately 14% of all available addresses utilized.[18]) While these numbers are very large, it was not the intent of the designers of the IPv6 address space to assure geographical saturation with usable addresses. Rather, the longer addresses simplify allocation of addresses, enable efficient route aggregation, and allow implementation of special addressing features. In IPv4, complex Classless 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, the square of the size of the entire IPv4 address space. Thus, actual address space utilization rates will be small in IPv6, but network management and routing efficiency is improved by the large subnet space and hierarchical route aggregation.

Renumbering an existing network for a new connectivity provider with different routing prefixes is a major effort with IPv4.[19][20] 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.[citation needed]

Multicasting

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.[21] IPv6 multicast addressing shares common features and protocols 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 can be achieved by sending a packet to the link-local all nodes multicast group at address ff02::1, which is analogous to IPv4 multicast to address 224.0.0.1. IPv6 also supports new multicast solutions, including embedding rendezvous point addresses in an IPv6 multicast group address which simplifies the deployment of inter-domain solutions.[22]

In IPv4 it was very difficult for an organization to get even one globally routable multicast group assignment and the implementation of inter-domain solutions was very arcane.[23] Unicast address assignments by a local 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.[citation needed] Thus each user of an IPv6 subnet automatically has available a set of globally routable source-specific multicast groups for multicast applications.[24]

Stateless address autoconfiguration (SLAAC)

See also: IPv6 address

IPv6 hosts can configure themselves automatically when connected to a routed IPv6 network using Internet Control Message Protocol version 6 (ICMPv6) router discovery messages. When first connected to a network, a host sends a link-local router solicitation multicast request for its configuration parameters; if configured suitably, routers respond to such a request with a router advertisement packet that contains network-layer configuration parameters.[25]

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

Routers present a special case of requirements for address configuration, as they often are sources for autoconfiguration information, such as router and prefix advertisements. Stateless configuration for routers can be achieved with a special router renumbering protocol.[26]

Mandatory support for network layer security

Internet Protocol Security (IPsec) was originally developed for IPv6, but found widespread deployment first in IPv4, into which it was back-engineered. IPsec is an integral part of the base protocol suite in IPv6.[1] IPsec support is mandatory in IPv6 but optional for IPv4.

Simplified processing by routers

In IPv6, the packet header and the process of packet forwarding have been simplified. Although IPv6 packet headers are at least twice the size of IPv4 packet headers, packet processing by routers is generally more efficient,[1][16] thereby extending the end-to-end principle of Internet design. Specifically:

  • The packet header in IPv6 is simpler than that used in IPv4, with many rarely used fields moved to separate optional header extensions.
  • IPv6 routers do not perform fragmentation. IPv6 hosts are required to either perform path MTU discovery, perform end-to-end fragmentation, or to send packets no larger than the IPv6 default minimum MTU size of 1280 octets.
  • The IPv6 header is not protected by a checksum; integrity protection is assumed to be assured by both link layer and higher layer (TCP, UDP, etc.) error detection.[note 1] Therefore, IPv6 routers do not need to recompute a checksum when header fields (such as the time to live (TTL) or hop count) change.[note 2]
  • The TTL field of IPv4 has been renamed to Hop Limit, reflecting the fact that routers are no longer expected to compute the time a packet has spent in a queue.

Mobility

Unlike mobile IPv4, mobile IPv6 avoids triangular routing and is therefore as efficient as native IPv6. IPv6 routers may also support network mobility which allows entire subnets to move to a new router connection point without renumbering.[27]

Options extensibility

The IPv6 protocol header has a fixed size (40 octets). Options are implemented as additional extension headers after the IPv6 header, which limits their size only by the size of an entire packet. The extension header mechanism provides extensibility to support future services for quality of service, security, mobility, and others, without redesign of the basic protocol.[1]

Jumbograms

IPv4 limits packets to 65535 (216 - 1) octets of payload. IPv6 has optional support for packets over this limit, referred to as jumbograms, which can be as large as 4294967295 (232 - 1) octets. The use of jumbograms may improve performance over high-MTU links. The use of jumbograms is indicated by the Jumbo Payload Option header.[28]

Packet format

Main article: IPv6 packet
IPv6 packet header.

The IPv6 packet is composed of two parts: the packet header and the payload. The header consists of a fixed portion with minimal functionality required for all packets and may contain optional extension 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 classification options, a hop counter, and a pointer for extension headers if any. The Next Header field, present in each extension as well, points to the next element in the chain of extensions. The last field points to the upper-layer protocol that is carried in the packet's payload.

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

The payload can have a size of up to 64KB without special options, or larger with a jumbo payload option in a Hop-By-Hop Options extension header.

Unlike in IPv4, fragmentation is handled only in the end points of a communication session; routers never fragment a packet, and hosts are expected to use Path MTU Discovery to select a packet size that can traverse the entire communications path.

Addressing

Main article: IPv6 address

The most important feature of IPv6 is a much larger address space than in IPv4. IPv6 addresses are 128 bits long, compared to only 32 bits previously.[29] While the IPv4 address space contains only about 4.3×109 (4.3 billion) addresses, IPv6 supports approximately 3.4×1038 (340 undecillion) unique addresses, deemed enough for the foreseeable future.[30]

IPv6 addresses are written in eight groups of four hexadecimal digits separated by colons, for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334. IPv6 addresses are logically divided into two parts: a 64-bit (sub-)network prefix, and a 64-bit interface identifier.

For SLAAC to work, subnets require at least a /64 address block, which is 1/(264) of total IPv6 address space. Local Internet registries get assigned at least /32 blocks, which they divide among ISPs.[31] The obsolete RFC 3177 recommended the assignment of a /48 to end consumer sites. This was replaced by RFC 6177, which "recommends giving home sites significantly more than a single /64, but does not recommend that every home site be given a /48 either." /56s are specifically considered.

IPv6 addresses are classified by three types of networking methodologies: unicast addresses identify each network interface, anycast addresses identify a group of interfaces, usually at different locations of which the nearest one is automatically selected, and multicast addresses are used to deliver one packet to many interfaces. The broadcast method is not implemented in IPv6. Each IPv6 address has a scope, which specifies in which part of the network it is valid and unique. Some addresses are unique only on the local (sub-)network; Others are globally unique.

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

IPv6 in the Domain Name System

Main article: IPv6 address § IPv6 addresses in the Domain Name System

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

Address Format

IPv6 addresses have two logical parts: a 64-bit network prefix, and a 64-bit host address part. (The host address is often automatically generated from the interface MAC address.[32]) An IPv6 address is represented by 8 groups of 16-bit hexadecimal values separated by colons (:) shown as follows:

A typical example of an IPv6 address is

2001:0db8:85a3:0000:0000:8a2e:0370:7334

The hexadecimal digits are case-insensitive.

The 128-bit IPv6 address can be abbreviated with the following rules:

  • Rule one: Leading zeroes within a 16-bit value may be omitted. For example, the address fe80:0000:0000:0000:0202:b3ff:fe1e:8329 may be written as fe80:0:0:0:202:b3ff:fe1e:8329
  • Rule two: A single occurrence of consecutive groups of zeroes within an address may be replaced by a double colon. For example, fe80:0:0:0:202:b3ff:fe1e:8329 becomes fe80::202:b3ff:fe1e:8329

Transition mechanisms

IPv6 transition mechanisms
Standards Track
Experimental
Informational
Drafts
Deprecated

Until IPv6 completely supplants IPv4, a number of transition mechanisms[33] are needed to enable IPv6-only hosts to reach IPv4 services and to allow isolated IPv6 hosts and networks to reach the IPv6 Internet over the IPv4 infrastructure.

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

  • RFC 2893, Transition Mechanisms for IPv6 Hosts and Routers, obsoleted by RFC 4213 Basic Transition Mechanisms for IPv6 Hosts and Routers
  • RFC 2766, Network Address Translation — Protocol Translation NAT-PT, obsoleted as explained in RFC 4966 Reasons to Move the Network Address Translator — Protocol Translator NAT-PT to Historic Status
  • RFC 2185, Routing Aspects of IPv6 Transition
  • RFC 3493, Basic Socket Interface Extensions for IPv6
  • RFC 3056, Connection of IPv6 Domains via IPv4 Clouds
  • RFC 4380, Teredo: Tunneling IPv6 over UDP through Network Address Translations NATs
  • RFC 4214, Intra-Site Automatic Tunnel Addressing Protocol ISATAP
  • RFC 3053, IPv6 Tunnel Broker
  • RFC 3142, An IPv6-to-IPv4 Transport Relay Translator
  • RFC 5569, IPv6 Rapid Deployment on IPv4 Infrastructures (6rd)
  • RFC 5572, IPv6 Tunnel Broker with the Tunnel Setup Protocol (TSP)

Dual IP stack implementation

The dual-stack protocol implementation in an operating system is a fundamental IPv4-to-IPv6 transition technology. It implements IPv4 and IPv6 protocol stacks either independently or in a hybrid form. The hybrid form is commonly implemented in modern operating systems supporting IPv6. Dual-stack hosts are described in RFC 4213.

Modern hybrid dual-stack implementations of IPv4 and IPv6 allow programmers to write networking code that works transparently on IPv4 or IPv6. The software may use hybrid sockets designed to accept both IPv4 and IPv6 packets. When used in IPv4 communications, hybrid stacks use an IPv6 application programming interface and represent IPv4 addresses in a special address format, the IPv4-mapped IPv6 address.

IPv4-mapped IPv6 addresses

Hybrid dual-stack IPv6/IPv4 implementations support a special class of addresses, the IPv4-mapped IPv6 addresses. This address type has its first 80 bits set to zero and the next 16 set to one, while its last 32 bits are filled with the IPv4 address. These addresses are commonly represented in the standard IPv6 format, but having the last 32 bits written in the customary dot-decimal notation of IPv4; for example, ::ffff:192.0.2.128 represents the IPv4 address 192.0.2.128. It substitutes the old and deprecated IPv4-compatible IPv6 address formed by ::192.0.2.128.[34]

Because of the significant internal differences between IPv4 and IPv6, some of the lower level functionality available to programmers in the IPv6 stack do not work identically with IPv4 mapped addresses. Some common IPv6 stacks do not support 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) .[35] On these operating systems, it is necessary to open a separate socket for each IP protocol that is to be supported. On some systems, e.g., the Linux kernel, NetBSD, and FreeBSD, this feature is controlled by the socket option IPV6_V6ONLY as specified in RFC 3493.[36]

Tunneling

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

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

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

Automatic tunneling

Automatic tunneling refers to a technique where the routing infrastructure automatically determines the tunnel endpoints.

6to4 is recommended by RFC 3056 tunneling method for automatic tunneling, which uses protocol 41 encapsulation.[37] Tunnel endpoints are determined by using a well-known IPv4 anycast address on the remote side, and embedding IPv4 address information within IPv6 addresses on the local side. 6to4 is widely deployed today.

Teredo is an automatic tunneling technique that uses UDP encapsulation and can allegedly cross multiple NAT boxes.[38] IPv6, including 6to4 and Teredo tunneling, are enabled by default in Windows Vista[39] and Windows 7. Most Unix systems only implement native support for 6to4, but Teredo can be provided by third-party software such as Miredo.

ISATAP[40] treats the IPv4 network as a virtual IPv6 local link, with mappings from each IPv4 address to a link-local IPv6 address. Unlike 6to4 and Teredo, which are inter-site tunnelling mechanisms, ISATAP is an intra-site mechanism, meaning that it is designed to provide IPv6 connectivity between nodes within a single organisation.

Configured and automated tunneling (6in4)

In configured tunneling, the tunnel endpoints are explicitly configured, either by an administrator manually or the operating system's configuration mechanisms, or by an automatic service known as a tunnel broker;[41] this is also referred to as automated tunneling. Configured tunneling is usually more deterministic and easier to debug than automatic tunneling, and is therefore recommended for large, well-administered networks. Automated tunneling provides a compromise between the ease of use of automatic tunneling and the deterministic behaviour of configured tunneling.

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

Proxying and translation for IPv6-only hosts

Main article: IPv6 transition mechanisms

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

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

NAT-like techniques for application-agnostic translation at the lower layers in routers and gateways have been proposed. The NAT-PT standard was dropped due to a number of criticisms,[42] however more recently the continued low adoption of IPv6 has prompted a new standardization effort under the name NAT64.

IPv6 readiness

Compatibility with IPv6 networking is mainly a software or firmware issue. However, much of the older hardware that could in principle be upgraded is likely to be replaced instead. The American Registry for Internet Numbers (ARIN) suggests that all Internet servers be prepared to serve IPv6-only clients by January 2012.[43][44]

Software

Most personal computers running recent operating system versions are IPv6-ready. Most applications with network capabilities are not ready but could be upgraded with support from the developers. Java applications adhering to Java 1.4 (February 2002) standards have support for IPv6.[45]

Hardware and embedded systems

Low-level equipment like network adapters and network switches may not be affected by the change, since they transmit link layer frames without inspecting the contents. Networking devices that obtain IP addresses or perform routing based on IP address do need IPv6 support.

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

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

Consumers tend to look at networking devices like household appliances that only rarely need repairs and never have to be configured or updated. Little effort has been made at educating consumers about the need to upgrade.[citation needed]

The CableLabs consortium published the 160 Mbit/s DOCSIS 3.0 IPv6-ready specification for cable modems in August 2006. The widely used DOCSIS 2.0 does not support IPv6. The new 'DOCSIS 2.0 + IPv6' standard also supports IPv6, which may on the cable modem side only require a firmware upgrade.[46][47] It is expected that only 60% of cable modems' servers and 40% of cable modems will be DOCSIS 3.0 by 2011.[48]

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

Deployment

Main article: IPv6 deployment

The introduction of Classless Inter-Domain Routing (CIDR) in the Internet routing and IP address allocation methods in 1993 and the extensive use of network address translation (NAT) delayed the inevitable IPv4 address exhaustion. Final exhaustion occurred on February 3, 2011.[13]

In 2008, IPv6 accounted for a minuscule fraction of the used addresses and the traffic in the publicly-accessible Internet which is still dominated by IPv4.[49] In October 2010, 243 (83%) of the 294 top-level domains (TLDs) in the Internet supported IPv6 to access their domain name servers, and 203 (69%) zones contained IPv6 glue records, and approximately 1.4 million domains (1%) had IPv6 address records in their zones.[50] Of all networks in the global BGP routing table, 7.2% have IPv6 protocol support.

The 2008 Summer Olympic Games were a notable event in terms of IPv6 deployment, being the first time a major world event has had a presence on the IPv6 Internet at http://ipv6.beijing2008.cn/en and all network operations of the Games were conducted using IPv6.[51] At the time of the event, it was believed that the Olympics provided the largest showcase of IPv6 technology since the inception of IPv6.[52] Since that time, major providers of Internet services, such as Google, have begun to implement IPv6 access into their products.[53]

Cellular telephone systems present a large deployment field for Internet Protocol devices as mobile telephone service is being transitioned from 3G systems to next generation (4G) technologies in which voice is provisioned as a Voice over Internet Protocol (VoIP) service. This mandates the use of IPv6 for such networks. In the U.S., cellular operator Verizon has released technical specifications for devices operating on its future networks.[54] The specification mandates IPv6 operation according to the 3GPP Release 8 Specifications (March 2009) and deprecates IPv4 as an optional capability.[citation needed]

Some implementations of the BitTorrent peer-to-peer file transfer protocol make use of IPv6 to avoid NAT issues common for IPv4 private networks.[55]

All major operating systems in use as of 2010 on personal computers and server systems have production quality IPv6 implementations.[56] Microsoft Windows has supported IPv6 since Windows 2000, and in production ready state beginning with Windows XP. Windows Vista and later have improved IPv6 support.[57] Mac OS X Panther (10.3), Linux 2.6, FreeBSD, and Solaris also have mature production implementations.

Controversy

Privacy extensions are, except for the Windows platform, not enabled by default. That the unique MAC address is exposed to the internet and therefore makes devices trackable caused criticism of data privacy responsibles in various countries. Two actions are necessary to guarantee the same level as with today's IPv4 networks: the client device has the privacy extensions enabled, and the provider dynamically assigns a varying address block to the client device. [58][59][60][61][62]

Major milestones

Year Major development and availability milestones
1996 Alpha quality IPv6 support in Linux kernel development version 2.1.8.[63]
6bone (an IPv6 virtual network for testing) is started.
1997 By the end of 1997 IBM's AIX 4.3 is the first commercial platform supporting IPv6.[64][65]
Also in 1997, Early Adopter Kits for DEC's operating systems, Tru64 and OpenVMS, are made available.[66]
1998 Microsoft Research[67] releases its first experimental IPv6 stack. This support is not intended for use in a production environment.
2000 Production-quality BSD support for IPv6 becomes generally available in early to mid-2000 in FreeBSD, OpenBSD, and NetBSD via the KAME project.[68]
Microsoft releases an IPv6 technology preview version for Windows 2000 in March 2000.[67]
Sun Solaris supports IPv6 in Solaris 8 in February.[69]
Compaq ships IPv6 with Tru64.[66]
2001 In January, Compaq ships IPv6 with OpenVMS.[66]
Cisco Systems introduces IPv6 support on Cisco IOS routers and L3 switches.[70]
HP introduces IPv6 with HP-UX 11i v1.[71]
On April 23, 2001, the European Commission launches the European IPv6 Task Force[72]
2002 Microsoft Windows NT 4.0 and Windows 2000 SP1 have limited IPv6 support for research and testing since at least 2002.
Microsoft Windows XP (2001) supports IPv6 for developmental purposes. In Windows XP SP1 (2002) and Windows Server 2003, IPv6 is included as a core networking technology, suitable for commercial deployment.[73]
IBM z/OS supports IPv6 since version 1.4 (generally availability in September 2002).[74]
2003 Apple Mac OS X v10.3 "Panther" (2003) supports IPv6 which is enabled by default.[75]
2004 In July, ICANN announces that IPv6 address records for the Japan (jp) and Korea (kr) country code top-level domain nameservers are visible in the DNS root server zone files with serial number 2004072000. The IPv6 records for France (fr) are added later. This makes IPv6 DNS publicly operational.
2005 Linux 2.6.12 removes experimental status from its IPv6 implementation.[76]
2007 Microsoft Windows Vista (2007) supports IPv6 which is enabled by default.[73]
Apple's AirPort Extreme 802.11n base station includes an IPv6 gateway in its default configuration. It uses 6to4 tunneling and manually configured static tunnels.[77] (Note: 6to4 was disabled by default in later firmware revisions.)
2008 On February 4, 2008, IANA adds AAAA records for the IPv6 addresses of six root name servers.[78][79] With this transition, it is now possible to resolve domain names using only IPv6.
On March 12, 2008, Google launches a public IPv6 web interface to its popular search engine at the URL http://ipv6.google.com.[53]
On March 12, 2008, IETF does an hour long IPv4 blackout at its meeting as an opportunity to capture informal experience data to inform protocol design work going forward;[80] this led to many fixes in operating systems and applications.
On May 27, 2008, the European Commission publish their Action Plan for the deployment of Internet Protocol version 6 (IPv6) in Europe, with the aim of making IPv6 available to 25% of European users by 2010.[81]
2009 In January 2009, Google extends its IPv6 initiative with Google over IPv6, which offers IPv6 support for Google services to compatible networks.
2011 On June 8, 2011 the Internet Society together with several other big companies and organizations will hold World IPv6 Day, a global 24 hour test of IPv6.[82][83]

See also

Notes

  1. ^ UDP/IPv4 may actually have a checksum of 0, indicating no checksum; IPv6 requires UDP to have its own checksum.
  2. ^ This improvement may have been made less necessary by the development of routers that perform checksum computation at link speed using dedicated hardware, but it is still relevant for software based routers.

References

  1. ^ a b c d e f RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, S. Deering, R. Hinden (December 1998)
  2. ^ [1]
  3. ^ Google: more Macs mean higher IPv6 usage in US
  4. ^ Global IPv6 Statistics - Measuring the current state of IPv6 for ordinary users, S. H. Gunderson (Google), RIPE 57 (Dubai, Oct 2008)
  5. ^ a b c RFC 1752 The Recommendation for the IP Next Generation Protocol, S. Bradner, A. Mankin, January 1995.
  6. ^ RFC 1550, IP: Next Generation (IPng) White Paper Solicitation, S. Bradner, A. Mankin (December 1993)
  7. ^ History of the IPng Effort
  8. ^ http://arstechnica.com/tech-policy/news/2011/02/river-of-ipv4-addresses-officially-runs-dry.ars
  9. ^ "Two /8s allocated to APNIC from IANA". APNIC. 2010-01-01. Retrieved 2011-02-03.
  10. ^ Exec: No shortage of Net addresses By John Lui, CNETAsia
  11. ^ A Pragmatic Report on IPv4 Address Space Consumption by Tony Hain, Cisco Systems
  12. ^ Proposed Global Policy for the Allocation of the Remaining IPv4 Address Space
  13. ^ a b IPv4 Address Report
  14. ^ Rashid, Fahmida Y. (February 3, 2011). "IPv4 Address Depletion Adds Momentum to IPv6 Transition". eWeek.com. Retrieved February 3, 2011.
  15. ^ Asia-Pacific Network Information Centre (15 April 2011). "APNIC IPv4 Address Pool Reaches Final /8". Retrieved 15 April 2011.
  16. ^ a b RFC 1726, Technical Criteria for Choosing IP The Next Generation (IPng), Partridge C., Kastenholz F. (December 1994)
  17. ^ U.S. Census Bureau
  18. ^ "Moving to IPv6: Now for the hard part (FAQ) | Deep Tech - CNET News". Retrieved 2011-02-03.
  19. ^ RFC 2071, Network Renumbering Overview: Why would I want it and what is it anyway?, P. Ferguson, H. Berkowitz (January 1997)
  20. ^ RFC 2072, Router Renumbering Guide, H. Berkowitz (January 1997)
  21. ^ RFC 1112, Host extensions for IP multicasting, S. Deering (August 1989)
  22. ^ RFC 3956, Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address, P. Savola, B. Haberman (November 2004)
  23. ^ RFC 2908, The Internet Multicast Address Allocation Architecture, D. Thaler, M. Handley, D. Estrin (September 2000)
  24. ^ RFC 3306
  25. ^ RFC 4862, IPv6 Stateless Address Autoconfiguration, S. Thomson, T. Narten, T. Jinmei (September 2007)
  26. ^ RFC 2894, Router Renumbering for IPv6, M. Crawford, August 2000.
  27. ^ RFC 3963, Network Mobility (NEMO) Basic Protocol Support, V. Devarapalli, R. Wakikawa, A. Petrescu, P. Thubert (January 2005)
  28. ^ RFC 2675, IPv6 Jumbograms, D. Borman, S. Deering, R. Hinden (August 1999)
  29. ^ RFC 4291 IP Version 6 Addressing Architecture, R. Hinden, S. Deering (February 2006)
  30. ^ The sheer size of IPv6
  31. ^ "IPv6 Address Allocation and Assignment Policy". RIPE NCC. 8 February 2011. Retrieved 27 March 2011.
  32. ^ To convert a 48-bit MAC address to IPv6 EUI-64 format host address, first the 7th bit (scope bit) is flipped (so, for instance, 00 becomes 02 and vice-versa). Then 2 bytes with the value 0xFFFE are inserted between the vendor portion (the first 3 bytes) and the host portion (the last 3 bytes) of the MAC address. This pads the 48-bit address to 64 bits."Recipe 25.1. Automatically Generating IPv6 Addresses for an Interface". Retrieved 14 March 2011.
  33. ^ IPv6 Transition Mechanism / Tunneling Comparison
  34. ^ RFC4291
  35. ^ OpenBSD inet6(4) manual page
  36. ^ http://tools.ietf.org/html/rfc3493#page-22
  37. ^ RFC 3056 Connection of IPv6 Domains via IPv4 Clouds, B. Carpenter, Februari 2001.
  38. ^ RFC 4380 Teredo: Tunneling IPv6 over UDP through Network Address Translations (NATs), C. Huitema, Februari 2006
  39. ^ The Windows Vista Developer Story: Application Compatibility Cookbook
  40. ^ RFC 5214 Intra-Site Automatic Tunnel Addressing Protocol (ISATAP), F. Templin, T. Gleeson, D. Thaler, March 2008.
  41. ^ RFC 3053, IPv6 Tunnel Broker, A. Durand, P. Fasano, I. Guardini, D. Lento (January 2001)
  42. ^ RFC 4966 Reasons to Move the Network Address Translator - Protocol Translator (NAT-PT) to Historic Status
  43. ^ Web sites must support IPv6 by 2012, expert warns, Network World, 21 January 2010, retrieved 2010-09-30
  44. ^ RFC 5211
  45. ^ "Networking IPv6 User Guide for JDK/JRE 5.0". Retrieved 2007-09-30.
  46. ^ "DOCSIS 2.0 Interface". Cablemodem.com. 2007-10-29. Retrieved 2009-08-31.
  47. ^ RMV6TF.org
  48. ^ "DOCSIS 3.0 Network Equipment Penetration to Reach 60% by 2011" (Press release). ABI Research. 2007-08-23. Retrieved 2007-09-30.
  49. ^ Geoff Huston - An Update on IPv6 Deployment (RIPE 56)
  50. ^ Mike Leber (2010-10-02). "Global IPv6 Deployment Progress Report". Hurricane Electric. Retrieved 2010-10-02.
  51. ^ "Beijing2008.cn leaps to next-generation Net" (Press release). The Beijing Organizing Committee for the Games of the XXIX Olympiad. 2008-05-30.
  52. ^ Das, Kaushik (2008). "IPv6 and the 2008 Beijing Olympics". IPv6.com. Retrieved 2008-08-15. As thousands of engineers, technologists have worked for a significant time to perfect this (IPv6) technology, there is no doubt, this technology brings considerable promises but this is for the first time that it will showcase its strength when in use for such a mega-event. {{cite web}}: Cite has empty unknown parameter: |month= (help)
  53. ^ a b Official Google Blog announcing IPv6 support
  54. ^ Derek Morr (2009-06-09). "Verizon Mandates IPv6 Support for Next-Gen Cell Phones". CircleID.
  55. ^ Rob Issac (2008), Welcome to your IPv6 enabled transit network. Whether you like it, or not (PDF)
  56. ^ Comparison of IPv6 support in operating systems Comparison of IPv6 support in operating systems
  57. ^ Vista: How PPPv6 support works?
  58. ^ [2], Privacy Extensions for Stateless Address Autoconfiguration in IPv6, T. Narten, R. Draves, 2001-01.
  59. ^ Statement on IPv6 Address Privacy, Steve Deering & Bob Hinden, Co-Chairs of the IETF's IP Next Generation Working Group , 1999-11-06.
  60. ^ IPv6: Privacy Extensions einschalten, Reiko Kaps, 2011-04-13
  61. ^ Privacy Extensions (IPv6), Elektronik Kompendium.
  62. ^ Neues Internet-Protokoll erschwert anonymes Surfen, Konrad Lischka, Spiegel Online, 2010-11-18.
  63. ^ Linux IPv6 Development Project
  64. ^ IPv6 support shipping in AIX 3.3
  65. ^ Its AIX 4.3.
  66. ^ a b c DEC/Compaq IPv6 history
  67. ^ a b Internet Protocol Version 6 (old Microsoft Research IPv6 release)
  68. ^ KAME project
  69. ^ Sun Solaris 8 changes from Solaris 7
  70. ^ Cisco main IPv6 site
  71. ^ HP main IPv6 site
  72. ^ IPv6 and Broadband ISBN 3-00-013801, published 2005, accessed 2011-01-12
  73. ^ a b Microsofts main IPv6 site
  74. ^ "IBM: z/OS operating system". 03.ibm.com. Retrieved 2009-08-31.
  75. ^ Mac OS X 10.3 Using IPv6 *** Document not found error message *** 2008-11-14
  76. ^ Linux 2.6.12 changelog
  77. ^ Apple AirPort Extreme technical specifications.
  78. ^ IPv6: coming to a root server near you
  79. ^ IANA - IPv6 Addresses for the Root Servers
  80. ^ IETF 71 IPv4 Outage
  81. ^ Action Plan for the deployment of Internet Protocol version 6 (IPv6) in Europe The IPv6 Portal, published 2008-05-27, accessed 2011-01-12
  82. ^ World IPv6 Day Internet Society, accessed 2011-05-25
  83. ^ ISOC Monthly Newsletter - Major Websites Commit to 24-Hour Test Flight for IPv6 Internet Society, published 2011-01-12, accessed 2011-05-25
Retrieved from "https://en.wikipedia.org/w/index.php?title=IPv6&oldid=432371744"