IPv6
IPv6 is version 6 of the Internet Protocol.
IPv6 is the second version of the Internet Protocol to be widely deployed, and is expected to form the basis for future expansion (as of 2001) of the Internet, replacing the previous standard, IPv4. The previous standard could hold up to 4 billion adresses, whereas IPv6 can hold up to as many as 3.4 × 1038 addresses.
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 among others which do not have enough address space for their use.
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2 Notation for IPv6 addresses 3 IPv6 deployment 4 Related IETF working groups 5 External links |
The most dramatic change from IPv4 to IPv6 is the length of the network addresses used. IPv6 addresses, as defined by RFC 2373 and RFC 2374, are 128 bits long and are written in hexadecimal with colons. The number of available addresses in IPv6 is 2128 = 3.4 x 1038 (cf. 232 = 4 billion addresses in IPv4). Another way to calculate is 1632 as there are 16 combinations per each digit and 32 digits.
In some 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.
If a 4 digit group is 0000, it may be omitted, thus in the syntax of IPv6
Also leading zero's in all groups can be omitted, thus
IPv4 adresses are easily convertable to IPv6 format. For instance, if the IPv4 adress was 135.75.43.52, 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 mapped adresses), in which case the adress would be ::135.75.43.52 .
IPv6 addressing
Notation for IPv6 addresses
IPv6 addresses are 128 bits long, and can be written as eight groups of 4 hexadecimal digits each. For example,
3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344
is a valid address.3ffe:6a88:85a3:0000:1319:8a2e:0370:7344
is the same as
3ffe:6a88:85a3::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 more than two consecutive colons. Thus
2001:2353:0000:0000:0000:0000:1428:57ab
2001:2353:0000:0000:0000::1428:57ab
2001:2353:0:0:0:0:1428:57ab
2001:2353:0::0:1428:57ab
2001:2353::1428:57ab
are all valid and mean the same thing, but
2001::25de::cade
is invalid.2001:2353:02de::0e13
is the same thing as
2001:2353:2de::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 a IPv4-mapped address, and is deprecated. The ::1.2.3.4 format is a IPv4-compatible address.IPv6 deployment
To do:
Related IETF working groups
External links
