The Internet Protocol Version 6 ( IPv6 ) is the latest version of Internet Protocol (IP), a communication protocol that provides identification and location systems for computers on the network and traffic routes on the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to address the long-anticipated issue of depleted IPv4 addresses. IPv6 is meant to replace IPv4. IPv6 became the Standard Bill in December 1998, and became the Internet Standard on July 14, 2017.
Each device on the Internet is assigned a unique IP address for location identification and definition. With the rapid growth of the Internet after commercialization in the 1990s, it became clear that more addresses would be required to connect devices from IPv4 address space already available. In 1998, the Internet Engineering Task Force (IETF) has formalized the successor protocol. IPv6 uses a 128-bit address, theoretically allows 2 128 , or about 3,4 ÃÆ' - 10 38 . The actual number is slightly smaller, as some ranges are reserved for special use or are completely excluded from use. The total number of IPv6 addresses that allow more than 7.9 ÃÆ' - 10 28 times as much as IPv4, which uses 32-bit addresses and provides about 4 , 3 billion addresses. Both of these protocols are not designed to be operable, complicating the transition to IPv6. However, some IPv6 transition mechanisms have been designed to allow communication between IPv4 and IPv6 hosts.
IPv6 provides other technical benefits in addition to the larger addressing space. Specifically, it allows a hierarchical address allocation method that facilitates route aggregation across the Internet, and thus limits the extension of the routing table. The use of multicast addressing is expanded and simplified, and provides additional optimization for service delivery. Device mobility, security, and configuration aspects have been considered in protocol design.
IPv6 addresses are represented as eight groups of four hexadecimal digits with colon-separated groups such as 2001: 0db8: 0000: 0042: 0000: 8a2e: 0370: 7334, but methods for abbreviating this complete notation exist.
Video IPv6
Key features
IPv6 is an Internet Layer protocol for packet-switched internetworking and provides end-to-end datagram transmissions across multiple IP networks, which closely follow the design principles developed in earlier protocol versions of Internet Protocol Version 4 (IPv4). IPv6 was first formally described in the Internet standard RFC 1883 document, published in December 1995. The RFC was obsolete and replaced by RFC 2460, published in December 1998. In July 2017, this specification has been deprecated and replaced by RFC 8200.
In addition to offering more addresses, IPv6 also implements features that do not exist in IPv4. This simplifies aspects of address assignment (automatic configuration of stateless addresses), network redialing, and router announcements when changing network connectivity providers. This simplifies packet processing on the router by placing the responsibility for packet fragmentation to the endpoint. The IPv6 subnet size is standardized by setting the size of the host identifier portion of the address to 64 bits to facilitate the automated mechanism to form the host identifier of the link layer addressing information (MAC address). Network security is an IPv6 architecture design requirement, and includes the original IPsec specification.
IPv6 does not specify interoperability features with IPv4, but basically creates a parallel and independent network. Swapping traffic between two networks requires a translator gate using one of several transition mechanisms, such as NAT64, or tunnel protocols such as 6to4, 6in4, or Teredo.
Maps IPv6
Motivation and origin
IPv4
Internet Protocol Version 4 (IPv4) is the Internet Protocol version that was first used publicly. IPv4 was developed as a research project by the Agency for Advanced Defense Research Project (DARPA), a US Department of Defense institution, before it became the foundation for the Internet and the World Wide Web. Currently described by the publication of IETF RFC 791 (September 1981), which replaces the previous definition (RFC 760, January 1980). IPv4 includes an addressing system that uses a numerical identifier consisting of 32 bits. These addresses are usually displayed in quad-dotted notes as decimal values ​​of four octets, each in the range 0 to 255, or 8 bits per number. Thus, IPv4 provides addressing capabilities of 2 32 or about 4.3 billion addresses. Address fatigue was initially not a concern in IPv4 because this version was originally regarded as a DARPA network concept test. During the first decade of Internet operation, it became clear that methods had to be developed to save address space. In the early 1990s, even after redesigning the addressing system using a classless network model, it became clear that this would not be enough to prevent IPv4 address exhaustion, and that further changes to the Internet infrastructure were required.
The last unsettled top-level address of 16 million IPv4 addresses was allocated in February 2011 by the Internet Assigned Numbers Authority (IANA) to five regional Internet Registries (RIRs). However, each RIR still has a set of available addresses and is expected to continue with standard address allocation policies until a fixed 8 Inter-Domain Routing (CIDR) block. After that, only the 1024 address (/22) blocks will be assigned from the RIR to the local Internet registry (LIR). Starting September 2015, the entire Asia-Pacific Network Information Center (APNIC), RÃÆ'  © seaux IP Europà ©       Network Coordination Center (RIPE_NCC), Latin America and Caribbean Network Information Center (LACNIC), and American Register for Internet Number (ARIN ) has reached this stage. It leaves the African Network Information Center (AFRINIC) as the only regional Internet registry that still uses a normal protocol to distribute IPv4 addresses.
Proposed workgroup
In early 1992, several proposals appeared for an expanded Internet addressing system and by the end of 1992 the IETF announced a call for a white paper. In September 1993, the IETF created an intermediate, ad-hoc IP (IPng) area to specifically address these issues. The new area is led by Allison Mankin and Scott Bradner, and has a directorate with 15 engineers from various backgrounds for review of directions and preliminary document review: Working group members are J. Allard (Steve), Steve Bellovin (AT & amp; 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 (Xerox).
The Internet Engineering Task Force adopted the IPng model on July 25, 1994, with the establishment of several IPng working groups. In 1996, a series of RFCs were released defining Internet Protocol version 6 (IPv6), starting with RFCÃ, 1883. (Version 5 is used by Experimental Internet Protocol Protocol.)
It is widely expected that the Internet will use IPv4 with IPv6 for the foreseeable future. Direct communication between IPv4 and IPv6 network protocols is not possible; therefore, an intermediary trans-protocol system is required as a communication channel between IPv4 and IPv6 either on one device or between network nodes.
Comparison with IPv4
On the Internet, data is transmitted in the form of network packets. IPv6 specifies a new package format, designed to minimize packet header processing by routers. Because IPv4 packet headers and IPv6 packets differ significantly, both protocols can not be operated. However, in many ways, IPv6 is an extension of IPv4. Most transport and application-layer protocols require little or no change to operate over IPv6; Exceptions are application protocols that embed Internet layer addresses, such as File Transfer Protocol (FTP) and Network Time Protocol (NTP), where new address formats can cause conflicts with existing protocol syntax.
Larger address space
The main advantage of IPv6 over IPv4 is the larger address space. The IPv6 address length is 128 bits, compared to 32 bits in IPv4. Therefore, the address space has an address of 2 128 or approximately 3,4 ÃÆ' - 10 38 .
Additionally, IPv4 address space is not allocated properly; in 2011, about 14% of all available addresses were used. Although these numbers are large, it is not the intent of the IPv6 address space designers to ensure geographical saturation with usable addresses. In contrast, longer addresses simplify address allocation, allow efficient route aggregation, and enable the implementation of special addressing features. In IPv4, complex Classless Inter-Domain Routing (CIDR) methods are developed to make the most of the small address space. The standard subnet size in IPv6 is 2 64 addresses, squared the size of the entire IPv4 address space. Thus, the actual address space utilization rate will be small in IPv6, but network management and routing efficiency are enhanced by subnet large space and hierarchical route aggregation.
Reorganizing existing networks for new connectivity providers with different routing prefixes is a big effort with IPv4. With IPv6, however, changing the prefix announced by some routers in principle can re-assign the entire network, since the host identifier (the most significant 64 bits of an address) can be independently configured solely by the host.
Multicasting
Multicasting, packet transmission to multiple destinations in a single delivery operation, is part of the basic specification in IPv6. In IPv4 this is an optional feature although it is generally implemented. 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 broadcasts, that is, packet delivery 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 the packet to the link-local all nodes of the multicast group at the address ff02 :: 1, which is analogous to IPv4 multicasting to address 224.0.0.1. IPv6 also provides a new multicast implementation, including embedding of meeting point addresses in IPv6 multicast group addresses, which simplifies the deployment of inter-domain solutions.
In IPv4, it is very difficult for an organization to get a globally routable multicast group task, and the implementation of inter-domain solutions is confidential. Unicast address assignments by the local Internet registry for IPv6 have at least 64-bit routing prefixes, resulting in the smallest subnet size available in IPv6 (also 64 bits). With such an assignment it is possible to embed the unicast address prefix into IPv6 multicast address format, while still providing 32-bit blocks, the most significant bit of the address, or about 4.2 billion multicast group identifiers. So each user of the IPv6 subnet automatically has provided a set of globally specially tailored multicast group for multicast applications.
Automatic configuration of address without status (SLAAC)
The IPv6 host can automatically configure itself when connected to an IPv6 network using the Neighbor Discovery Protocol via Internet Control Message Protocol version 6 (ICMPv6) router discovery message. When first connected to the network, the host sends a link-local router multicast request request for its configuration parameter; the router responds to such a request with a router ad package containing the Internet Layer configuration parameters. Routers present specific requirements for address configuration, as they are often sources of automated configuration information, such as routers and ad prefixes. Stateless router configuration can be achieved with the special router reset protocol.
If the automatic configuration of stateless IPv6 addresses does not match, IPv6 is the same as IPv4 allowing stateful configuration with Dynamic Host Configuration Protocol version 6 (DHCPv6) or manual host static configuration.
SLAAC privacy extensions
Like IPv4, IPv6 supports a unique global IP address. The IPv6 design is intended to re-emphasize the end-to-end network design principles that were originally conceived during the early Internet establishment. In this approach each device in the network has a unique address that can be reached globally directly from other locations on the Internet.
Unique IP addresses can potentially be used to track network activity of a device. Additionally, when using the automatic configuration of an IPv6 address, the Interface Identifier (MAC address) of the network card is used to create its unique public IPv6 interface identifier, exposing the type of hardware used and providing a unique grip for the user's online activities. Autoconfiguration on the basis of the MAC address of the network card because it is a particular privacy concerns for mobile devices, such as laptops, because when they access the Internet from different local area networks, their MAC based interface identifier will always remain the same. Thus, MAC address based address identifiers can be used to track movement and use of specific mobile devices.
When IPv6 was developed in the mid-1990s, the Internet was not accessed by a large number of mobile devices and privacy is not a priority that already exists today. To address this privacy issue, the SLAAC protocol has been updated with a mechanism called "Privacy Extension for Stateless Address Automatic Configuration in IPv6", codified in RFC 4941. This allows IPv6 address identifier identifiers to be generated randomly. If the same interface identifier is generated for two devices in the same local area network, the Duplicate Address Detection (DAD) function of the IPv6 Neighbor Discovery Protocol (NDP) will resolve the situation. The SLAAC privacy extension also implements a time-out, which can be configured, so that the IPv6 interface address will be removed and a new interface identifier is generated. Usually the timeout is configured up to 24 hours. So, automatic IPv6 configuration will generate and assign new IPv6 host addresses every day. By the end of 2014, the SLAAC privacy extension functionality is implemented by the following operating systems: all Microsoft Windows after Windows XP, all Mac OS X versions from 10.7 onwards, all iOS versions since 4.3, all Android versions since 4.0 (Ice Cream) Sandwich). The privacy extension is now enabled by default in Windows (since XP SP1), OS X (since 10.7), and iOS (since version 4.3). Some Linux distributions have enabled privacy extensions as well.
IPsec
Internet Protocol Security (IPsec) was originally developed for IPv6, but found the first widespread deployment in IPv4, which was reengineered. IPsec is a mandatory part of all IPv6 protocol implementations, and Internet Key Exchange is recommended. But with RFC 6434 the inclusion of IPsec in IPv6 implementation is downgraded to a recommendation because it is considered impractical to require full IPsec implementation for all types of devices that may be using IPv6. However, since the implementation of the IPv6 RFC 4301 protocol implementing the IPsec need to implement IKEv2 and need to support a minimum set of cryptographic algorithms. This requirement will help to make IPsec implementation more interoperable between devices from different vendors. The IPsec Authentication Header (AH) and Encapsulating Security Payload (ESP) headers are implemented as IPv6 extension headers.
Simplified process by router
The packet header in IPv6 is simpler than the IPv4 header. Many of the less used fields have been moved to the optional header extension. With a simplified IPv6 packet header, the packet delivery process by the router has been simplified. Although IPv6 packet headers are at least twice the size of IPv4 packet headers, packet processing by routers is generally more efficient, since fewer processing is required on routers because the headers are aligned to match common word sizes.
Additionally, the IPv6 header does not include checksums. IPv4 header headers are counted for IPv4 headers, and must be recalculated by the router each time the time to live (called the hop boundary in the IPv6 protocol) minus one. The absence of a checksum in IPv6 headers adds to the end-to-end principle of Internet design, which envisages that most of the processes in the network occur in leaf nodes. The integrity protection for data encapsulated in IPv6 packets is assumed to be guaranteed by link layer or error detection in higher layer protocols, namely Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) on layer transport. So while IPv4 allows UDP datagram headers do not have a checksum (indicated by 0 in the header field), IPv6 requires a checksum in the UDP header.
The IPv6 router does not perform IP fragmentation. An IPv6 host is required to search for MTU paths, perform end-to-end fragmentation, or send packets that are no larger than the Maximum standard transmission unit (MTU), which is 1280 octets.
Mobility
Unlike mobile IPv4, mobile IPv6 avoids triangular routing and is therefore as efficient as the original IPv6. The IPv6 router also allows all subnets to move to a new connection point of the router without a new number.
Header extension
The IPv6 packet header has a minimum size of 40 octets (320 bits). The options are implemented as extensions. This provides an opportunity to extend the protocol in the future without affecting the core package structure. However, a study in 2015 shows that some network operators drop IPv6 packets with extension headers as they traverse the transit autonomous system.
Jumbograms
IPv4 limit package up to 65,535 (2 16 -1) payload octets. The IPv6 node can optionally handle packets above this limit, called jumbograms, which can be 4,294,967,295 (2 32 -1) octets. The use of jumbograms can improve performance through high MTU links. The use of the jumbogram is indicated by the Jumbo Expense Options extension header.
IPv6 Package Format
IPv6 packets have two parts: header and payload.
The header consists of a fixed section with minimal functionality required for all packages and can be followed by optional extensions to apply special features.
The header still occupies the first 40 octets (320 bits) of the IPv6 packet. It contains source and destination addresses, traffic classification options, hop counters, and optional extension types or payloads that follow headers. This Next Header field tells the recipient how to interpret data that follows the header. If the package contains an option, this field contains the option type of the next option. The "Next Header" column of the last option, points to the upper layer protocol that is carried in the packet load.
The extension header brings options that are used for packet-specific treatment on the network, for example, for routing, fragmentation, and for security using the IPsec framework.
Without a custom option, the payload must be less than 64 KB . With the Jumbo Payload option (in the Hop-By-Hop Options header extension header), the payload must be less than 4Ã, GB.
Unlike IPv4, routers never break packets. The hosts are expected to use Path MTU Discovery to make their packets small enough to reach the destination without the need for fragmentation. See the fragmentation of IPv6 packets.
Addressing
The IPv6 address has 128 bits. The design of IPv6 address space implements a very different design philosophy than in IPv4, where subnetting is used to improve the efficiency of small address space utilization. In IPv6, the address space is considered large enough for the future, and the local area subnet always uses 64 bits for the host portion of the address, defined as the interface identifier, while the most significant 64 bits are used as the routing prefix.
The identifier is unique only within the subnet on which the host is connected. IPv6 has a mechanism for automatic address detection, so automatic address configuration always results in a unique task.
Address Representation
128 bits of IPv6 addresses are represented in 8 groups of 16 bits each. Each group is written as four hexadecimal digits (sometimes called hextets) and the group is separated by a colon (:). An example of this representation is 2001: 0db8: 0000: 0000: 0000: ff00: 0042: 8329 .
For convenience, IPv6 addresses can be shortened to shorter notation by applying the following rules.
- One or more zeroes in front of each hexadecimal number group are deleted; this is usually done for all or none of the original zeros. For example, group 0042 is converted to 42 .
- The consecutive portion of zero is replaced with a colon (: :). Double colons can only be used once in a single address, as multiple uses will render the address undetermined. RFCÃ, 5952 recommends that double colon is not used to denote a single portion of zero that is omitted.
Examples of applying these rules:
- Initial address: 2001: 0db8: 0000: 0000: 0000: ff00: 0042: 8329
- After deleting all zeros in each group: 2001: db8: 0: 0: 0: ff00: 42: 8329
- After removing consecutive parts from scratch: 2001: db8 :: ff00: 42: 8329
The loopback address, 0000: 0000: 0000: 0000: 0000: 0000: 0000: 0001 , may be abbreviated :: 1 using both rules.
Since IPv6 addresses may have more than one representation, the IETF has issued a proposed standard for representing it in text.
Address uniqueness
The host verifies the unique address given by sending a neighboring solicitation message requesting the Link Layer address from an IP address. If another host is using that address, it will respond. However, the MAC address is designed to be unique on every network card that minimizes the possibility of duplication.
The host first determines whether the network connects to all routers altogether, because otherwise all nodes can be reached using a locale-linked address assigned to the host. The host will send a Router Solicitation message to an all-router multicast group with a link-local address as the source. If there is no answer after a number of predetermined attempts, the host concludes that no router is connected. If you get a response from the router, there will be network information in it that is required to create a globally unique address. There are also two bit flags telling the host whether to use DHCP for more information and addresses:
- Manage bits, indicating whether or not the host should use DHCP to obtain additional addresses
- Other Bits, which indicate whether or not the host should get other information via DHCP. Other information consists of one or more prefix information options for the hosted attribute, lifetime for the prefix, and two flags:
- On-link: If this flag is set, the host will treat all addresses on a particular subnet as on-link, and send packets directly to them instead of sending them to the router for the given time duration.
- Address: This is a flag that tells the host to actually create a global address.
Local link-address
All IPv6 host interfaces require a link-local address. A link-local address is derived from the MAC address of the interface and the prefix fe80 :: / 10 . This process involves filling in the address space with the justified prefix for the most significant bit, and filling the MAC address in EUI-64 format into the least significant bit. If any remaining bits are to be filled between the two parts, everything is set to zero.
The uniqueness of the address on the subnet is tested by the Duplicate Address Detection (DAD) method.
Global handling
The assignment procedure for a global address is similar to the local address construction. This prefix is ​​supplied from router advertisements on the network. Some prefix announcements cause multiple addresses to be configured.
Stateless address autoconfiguration (SLAAC) requires address blocks 64 , as defined in RFCÃ, 4291. Local Internet Registry assigned at least / 32 block, which is shared between subordinate networks. The initial recommendation states the assignment of subnet / 48 to end consumer sites (RFC 3177). This was replaced by RFC 6177, which "recommends providing the homepage site significantly more than one 64 , but not recommend that each home site be / 48 good ". / 56 s is specifically considered. It remains to be seen whether the ISP will respect this recommendation. For example, during the initial trial, Comcast subscribers were assigned one network / 64 .
IPv6 addresses are classified by three types of network methodologies: unicast addresses identify each network interface, anycast address identifies a group of interfaces, usually in different locations where the closest one is automatically selected, and a multicast address is used to send one packet to multiple interfaces. Broadcasting methods are not implemented in IPv6. Each IPv6 address has coverage, which determines which part of the network is valid and unique. Some addresses are unique only in the local network (sub-). Others are globally unique.
Some IPv6 addresses are provided for specific purposes, such as loopback, 6to4 tunneling, and Teredo tunneling, as described in RFC 5156. Additionally, some address ranges are considered special, such as local-link addresses for use in local links only, unique local addresses (ULA ), as described in RFC 4193, and the secret-secret multicast addresses used in the Neighbor Discovery Protocol.
IPv6 in the Domain Name System
In Domain Name System, hostnames are mapped to IPv6 addresses by AAAA resource records, called quad-A notes. For back-resolutions, IETF reserves ip6.arpa domains, where hierarchical namespaces are shared by a 1-digit hexadecimal representation of nibble units (4 bits) of IPv6 addresses. This scheme is defined in RFC 3596.
At the design stage of IPv6 DNS architecture, AAAA schemes face competing proposals. This alternative approach, designed to facilitate network redialing, uses A6 notes for forward search and a number of other innovations such as bit-string and DNAME i> notes. This is defined in RFC 2874 and references (with further discussion of the pros and cons of both schemes in RFC 3364), but has been abandoned for experimental status (RFC 3363).
Transition mechanism
IPv6 is not foreseen to replace IPv4 instantly. Both protocols will continue to operate simultaneously for some time. Therefore, an IPv6 transition mechanism is required to enable IPv6 hosts to achieve IPv4 services and to allow isolated IPv6 hosts and networks to reach each other through IPv4 infrastructure.
According to Silvia Hagen the dual-stack implementation of IPv4 and IPv6 on devices is the easiest way to migrate to IPv6. Many other transitional mechanisms use tunneling to encapsulate IPv6 traffic in IPv4 networks. This is an imperfect solution, which reduces the maximum transmission unit (MTU) of a link and therefore complicates Path MTU Discovery, and can increase latency.
Dual-stack IP implementation
The dual-stack IP implementation provides a complete IPv4 and IPv6 protocol stack on the same network node above common physical layer implementations, such as Ethernet. This allows dual-stack hosts to participate in IPv6 and IPv4 networks simultaneously. This method is defined in RFC 4213.
Devices with dual-stack implementations have IPv4 and IPv6 addresses, and can communicate with other nodes on the LAN or the Internet using IPv4 or IPv6. The Domain Name System (DNS) protocol is used by both IP implementations to resolve fully qualified domain names (FQDN) and IP addresses, but the dual stack requires that the DNS settlement server be able to resolve both types of addresses. Such multiple stack DNS servers will store IPv4 addresses in A records, and IPv6 addresses in AAAA records. Depending on the purpose to be completed, the DNS name server can return IPv4 or IPv6 IP addresses, or both. The default address selection mechanism, or preferred protocol, needs to be configured either on the host or DNS server. IETF has published Happy Eyeballs to help dual stack applications, so they can connect using IPv4 and IPv6, but prefer IPv6 connections if available. Dual-stack also needs to be implemented on the router, so they can forward IPv6 packets using IPv6 routing protocol version. When the network protocol stack doubles in place the application layer can migrate to IPv6.
However, the outdated DNS server implementation does not support IPv6. While dual-stack is supported by large operating systems and network device vendors, legacy networking hardware and servers do not support IPv6. Various versions of Internet applications, such as File Transfer Protocol (FTP), do not support IPv6.
ISP customers with publicly facing IPv6
Internet service providers (ISPs) are increasingly providing their businesses and private customers with a global public unicast IP address. However, if in local area network (LAN) IPv4 is still in use, and ISPs can only provide public IPv6, LAN IPv4 addresses are translated to public IPv6 addresses using NAT64, the network address translation mechanism (NAT). Some ISPs can not provide their customers publicly facing IPv4 and IPv6, thus supporting dual stack, as some ISPs have run out of globally routable IPv4 addresses. Meanwhile, ISP customers are still trying to reach web servers and other destinations that have IPv4 addresses.
IPv6 addresses are in the process of being allocated worldwide. Significant percentage of ISPs in all Regional Internet Registry (RIR) zones have already gained IPv6 address space. These include many ISPs and major mobile network operators such as Verizon Wireless, StarHub Cable, Chubu Telecommunications, Cable Deutschland, Swisscom, T-Mobile, Internode, and Telefonica.
While there are still some ISPs that only allocate their DSL subscribers to IPv4, many ISPs allocate their customers only IPv6 or dual stack IPv4 and IPv6. ISPs report the share of IPv6 traffic from customers over their networks to anything between 20% and 40%, but by mid-2017 IPv6 traffic still accounts for only a fraction of total traffic at some major Internet exchange points (IXPs). AMS-IX reported it to 2% and Seattleix reported 7%. A 2017 survey found that many DSL subscribers served by double-stack ISPs do not require DNS servers to resolve fully qualified domain names to IPv6 addresses. The survey also found that most of the traffic from IPv6 ready-to-use web server resources is still requested and presented over IPv4, largely because ISP customers do not use the dual stack facilities provided by their ISPs and to a lesser extent because IPv4 customers - only ISP.
Tunneling
The technical base for tunneling, or encapsulating IPv6 packets in IPv4 packets, is described in RFC 4213. When the backbone of the Internet is IPv4 only one of the frequently used tunnel protocols is 6to4. Teredo tunneling is also often used to integrate IPv6 LAN with an IPv4 Internet backbone. Teredo is described in RFC 4380 and enables an IPv6 local area network to tunnel to an IPv4 network, encapsulating IPv6 packets in UDP. Teredo Relay is an IPv6 router that mediates between the Teredo server and the original IPv6 network. It is expected that 6to4 and Teredo will be used extensively until ISP networks will switch to the original IPv6, but by 2014, Google Stats show that the use of both mechanisms is down to almost 0.
IPv4 mapped IP address
IPv6/IPv4 dual-stack hybrid implementation recognizes a special class of addresses, IPv4 mapped IPv6 addresses. These addresses are made up of zero 80-bit prefixes, the next 16 bits are one, and the remainder, the least important 32 bits contain IPv4 addresses. These addresses are usually written with a 96-bit prefix in standard IPv6 format, and the remaining 32 bits are written in ordinary dot-decimal notation from IPv4. For example, Ã, :: ffff: 192.0.2.128 represents IPv4 address 192.0.2.128. The format that is not valid for IPv6 addresses that are compatible with IPv4 is :: 192.0.2.128.
Due to significant internal differences between IPv4 and IPv6, some of the low-level functions available to programmers in IPv6 stacks do not work together when used with IPv4 mapped addresses. Some common IPv6 stacks do not implement IPv4-mapped address features, either because the IPv6 and IPv4 stacks are separate implementations (for example, Microsoft Windows 2000, XP, and Server 2003), or because of security issues (OpenBSD). In this operating system, a program must open a separate socket for each IP protocol it uses. On some systems, for example, the Linux, NetBSD, and FreeBSD kernels, this feature is controlled by the IPV6_V6ONLY socket option, as specified in RFC 3493.
IPv6 readiness
Compatibility with the IPv6 network is primarily a software or firmware issue. However, many older hardware that in principle can be upgraded will likely be replaced. In 2010, the American Register for Internet Numbers (ARIN) suggested that all Internet servers are ready to serve IPv6-only clients by January 2012.
Application Software
The host software may have only IPv4 or only IPv6 network software, or it may support dual-stack operation, or dual-stack hybrid. The majority of personal computers running the latest operating system versions support IPv6. Many popular apps with compliant network capabilities. Some software switching mechanisms are described in RFC 4038, RFC 3493, and RFC 3542.
The embedded hardware and system
The CableLabs Consortium published 160 Mbit/s DOCSIS 3.0 IPv6-ready specifications for cable modems in August 2006. DOCSIS 2.0 was updated as DOCSIS 2.0 IPv6 to provide IPv6 support, which may be available with improved firmware.
Shadow network
The addition of nodes that have IPv6 enabled by the software manufacturer by default can result in the creation of accidental shadow networks , causing IPv6 traffic to flow to networks that only have IPv4 security management. This can also happen with an operating system upgrade, when newer operating systems allow IPv6 by default, while older ones do not. Failing to update the security infrastructure to accommodate IPv6 may cause IPv6 traffic to pass through. Shadow networks have occurred in business networks where companies are replacing Windows XP systems that do not have IPv6 stacks enabled by default, with Windows 7 systems, which do so. Therefore some IPv6 stack controllers recommend to disable IPv4 mapped addresses and instead use a dual-stack network where supporting both IPv4 and IPv6 is required.
Security
Research has shown that the use of fragmentation can be exploited to avoid network security control. As a result, RFC 7112 requires that the first fragment of IPv6 packets contain the entire IPv6 header chain, so some very pathological fragmentation cases are prohibited. In addition, as a result of research on RA-Guard evasion in RFC 7113, RFC 69 6980 has halted the use of fragmentation with Neighbor Discovery, and undermined the use of fragmentation with Secure Neighbor Discovery (SEND).
Implementation
Introduction to 1993 from Classless Inter-Domain Routing (CIDR) in routing and IP address allocation for the Internet, and extensive use of network address translation (NAT), delayed IPv4 address delays. The final phase of fatigue started on February 3, 2011. However, despite a decade of development and implementation history as the Standard Track protocol, worldwide IPv6 deployment is increasing slowly. As of September 2013, about 4% of domain names and 16.2% of networks on the Internet have IPv6 protocol support.
IPv6 has been applied to all major operating systems used in commercial, business, and consumer home environments. Since 2008, the domain name system can be used in IPv6. IPv6 was first used in major world events during the 2008 Summer Olympics, the largest IPv6 technology exhibition since the inception of IPv6. Several governments including the United States Federal government and China have issued guidelines and requirements for IPv6 capabilities.
In 2009, Verizon mandated IPv6 operations, and reduced IPv4 to optional capabilities, for LTE mobile devices. As of June 2012, T-Mobile USA also supports external IPv6 access.
In 2014, IPv4 still carries more than 99% of Internet traffic worldwide. Internet exchanges in Amsterdam and Seattle are the only major exchanges that publicly display IPv6 traffic statistics, which in April 2018 tracked about 2.2% and 10.7%, growing by 0.5% and 4.9% per year. As of April 30, 2018, the percentage of users reaching Google services with IPv6 reached 23.0% for the first time, growing by about 5.0% per year, though varies by region. In April 2018 about 27% of Alexa Top 1000 web servers support IPv6.
See also
- DHCPv6
- China's Next Generation Internet
- Comparison of IPv6 support in the operating system
- Comparison of IPv6 support in common applications
- DoD IPv6 product certification
- Happy Eyeballs
- IPv6 tunnel broker list
- The University of New Hampshire's Interoperability Laboratory
References
External links
- IPv6 in Linux Kernel by Rami Rosen.
- Free Swimming Pool from IPv4 Address Space Depleted
- Introduction and Statistics about IPv6
Source of the article : Wikipedia
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