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| There are eight groups of 4 digits each. The ] number system is used for the digits. Thus each group occupies 16 bits of space and the entire address represents (but does not always require) 128 bits. | There are eight groups of 4 digits each. The ] number system is used for the digits. Thus each group occupies 16 bits of space and the entire address represents (but does not always require) 128 bits. | ||
| For example, |
For example, 3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344. is a valid address | ||
| If a 4 digit group is 0000, it may be omitted, thus in the syntax of IPv6 | If a 4 digit group is 0000, it may be omitted, thus in the syntax of IPv6 | ||
| |
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 | 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, | are all valid and mean the same thing, | ||
| but |
but 2001::25de::cade is invalid. | ||
| Also leading zero's in all groups can be omitted, thus | Also leading zero's in all groups can be omitted, thus | ||
| |
2001:2353:02de::0e13 | ||
| is the same thing as | 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 | If the address is an IPv4 address in disguise, the last 32 bits may be written in decimal; thus | ||
Revision as of 15:54, 1 August 2003
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 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.
Syntax
There are eight groups of 4 digits each. The Hexadecimal number system is used for the digits. Thus each group occupies 16 bits of space and the entire address represents (but does not always require) 128 bits.
For example, 3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344. is a valid address
If a 4 digit group is 0000, it may be omitted, thus in the syntax of IPv6
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.
Also leading zero's in all groups can be omitted, thus
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.
IPv6 addressing
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 2 = 3.4 x 10 (cf. 2 = 4 billion addresses in IPv4). Another way to calculate is is 16 as there are 16 combinations per each digit and 32 digits.
IPv6 addresses are divided into two parts: a 64-bit routing part, and a 64-bit host-addressing part.
IPv6 deployment
To do: