IPv6 Guide, Meaning , Facts, Information and Description
IPv6 is version 6 of the Internet Protocol; it was initially called IP Next Generation (IPng) when it was picked as the winner in the IETF's IPng selection process. IPv6 is intended to replace the previous standard, IPv4, which only supports up to about 4 billion (4 × 109) addresses, whereas IPv6 supports up to about 3.4 × 1038 addresses. This is the equivalent of 4.3 × 1020 addresses per inch² (6.7 × 1017 addresses/mm²) of the Earth's surface. It is expected that IPv4 will be supported until at least 2025, to allow time for bugs and system errors to be corrected.
The compelling reason behind the formation of IPv6 was lack of address space, especially in the heavily populated countries of Asia such as India and China. See the article IPv4 address exhaustion for more on this topic. However since the introduction of NAT this is not such a big problem any more. Currently the big drive for IPv6 is new uses, such as mobility, quality of service, privacy extension and so on.
IPv6 is the second version of the Internet Protocol to be formally adopted for general use. (There was also an IPv5, but it was not a successor to IPv4; rather, it was an experimental flow-oriented streaming protocol, intended to support voice, video, and audio.)
The plan is for IPv6 to form the basis for future expansion of the Internet. Although IPv6 was adopted by the IETF as the successor to IPv4 over ten years ago (in 1994), worldwide IPv6 deployment as a publicly-accessible internet is still only a few percent [1] of the size of the worldwide IPv4 Internet [1].
The most dramatic change from IPv4 to IPv6 is the length of network addresses. IPv6 addresses, as defined by RFC 2373 and RFC 2374, are 128 bits long; this corresponds to 32 hexadecimal digits, which are normally used when writing IPv6 addresses, as described in the following section.
The number of possible addresses in IPv6 is 2128 ≈ 3.4 x 1038. The number of IPv6 addresses can also be thought of as 1632 as each of the 32 hexadecimal digits can take 16 values (see combinatorics).
In many situations, IPv6 addresses are composed of two logical parts: a 64-bit network prefix, and a 64-bit host-addressing part, which is often automatically generated from the interface MAC address. The host part is called a EUI-64 (or 64-bit Extended Unique Identifier).
IPv6 addresses are 128 bits long but are normally written as eight groups of 4 hexadecimal digits each. For example,
If a 4 digit group is 0000, it may be omitted. For example,
Also leading zeros in all groups can be omitted, thus
IPv4 addresses are easily convertible to IPv6 format. For instance, if the decimal IPv4 address was 135.75.43.52 (in hexadecimal, 0x874B2B34), it could be converted to 0000:0000:0000:0000:0000:0000:874B:2B34 or ::874B:2B34. Then again, one could use the hybrid notation (IPv4-compatible address), in which case the address would be ::135.75.43.52 .
The IPv6 packet is composed of two main parts; the header, and the payload.
The header is in the first 40 bytes of the packet and contains both source and destination addresses (128 bits each), as well as the version (4 bit IP version), traffic class (8 bit, Packet Priority), flow label (20 bits, QoS management), payload length (16 bit), next header (for backwards compatibility), and hop limit (8 bits, time to live). Next comes the payload, which must be at least 1280 bytes long, or 1500 bytes long in an environment with a flexible MTU size. The payload can go up to 65,535 in standard mode, or can be set to a "jumbo payload" option.
There have been two very slightly different versions of IPv6; the (now-obsolete) initial version, described in RFC 1883, differs from the current proposed standard version, described in RFC 2460, in one field. This is the traffic class, which has its size increased from 4 to 8 bits. All other differences are minor.
Fragmentation is handled in the host only in IPv6. In IPv6, options also move out of the standard header and are specified by a Next Protocol field, similar in function to IPv4's Protocol field.
IPv6 addresses are represented in the Domain Name System by AAAA records (so-called quad-A records) for forward lookups (by analogy with A records for IPv4); reverse lookupss take place under ip6.arpa (previously ip6.int), where address space is delegated on nibble boundaries. This scheme is defined in RFC 3596.
The AAAA scheme was one of two proposals at the time the IPv6 architecture was being designed. The other proposal would have had A6 records for the forward lookup and a number of other innovations such as bit-string labels and DNAME records. It is defined in the experimental RFC 2874 and its references.
While the AAAA scheme is a simple generalisation of the IPv4 DNS, the A6 scheme was an overhaul of the DNS to be more general, and hence more complex:
On 20 July 2004 ICANN announced[1] that the root DNS servers for the internet had been modified to support both IPv6 and IPv4.
Disadvantages:
This is an Article on IPv6. Page Contains Information, Facts Details or Explanation Guide About IPv6 IPv6 addressing
Notation for IPv6 addresses
2001:0db8:85a3:08d3:1319:8a2e:0370:7344
is a valid IPv6 address.2001:0db8:85a3:0000:1319:8a2e:0370:7344
is the same IPv6 address as
2001:0db8:85a3::1319:8a2e:0370:7344
Following this rule, if more than two consecutive colons result from this omission, they may be reduced to two colons, as long as there is only one group of two or more consecutive colons. Thus
2001:0DB8:0000:0000:0000:0000:1428:57ab
2001:0DB8:0000:0000:0000::1428:57ab
2001:0DB8:0:0:0:0:1428:57ab
2001:0DB8:0::0:1428:57ab
2001:0DB8::1428:57ab
are all valid and mean the same thing, but
2001::25de::cade
is invalid. (As it is ambiguous how many 0000 groups should be on each side.)2001:0DB8:02de::0e13
is the same thing as
2001:DB8:2de::e13
If the address is an IPv4 address in disguise, the last 32 bits may be written in decimal; thus ::ffff:192.168.89.9 is the same as
::ffff:c0a8:5909, but not the same as
::192.168.89.9 or
::c0a8:5909.
The ::ffff:1.2.3.4 format is called an IPv4-mapped address, and is deprecated. The ::1.2.3.4 format is an IPv4-compatible address.IPv6 packet
IPv6 and the Domain Name System
The AAAA scheme was effectively standardised on in August 2002 by RFC 3363 (with further discussion of the pros and cons of both schemes in RFC 3364).IPv6 deployment
To do:Major IPv6 announcements
Related IETF working groups
Further reading
External links