IPv6

IPv6 was developed to substitute IPv4, as it was expected to run out of addresses.

IPv6 Address

An IPv6 address uses 128 bits.

While IPV4 is represented by decimal numbers, IPv6 uses hexadecimal numbers.

There are 8 blocks of 4 hexadecimal numbers, representing each block 16 bits or 2 bytes. Each block is separated using colons (:).

Example of IPv6 address:

2001:0:9d38:6ab8:1c48:3a1c:a95a:b1c2

The IPv6 loopback address is 0:0:0:0:0:0:0:1 or ::1.

IPv6 Header

The header (with simple format and fixed length) is follow by optional extensions.

The IPv6 Header consists of:

• Version: 4 bits
• Traffic Class: 8 bits
• Flow label: 20 bits

The local link addresses are defined by the prefix FE80::/10.

The extension headers do not necessarily need to be examined by each node in the packet route.

The address can be configured applying the following methods:

• Autoconfiguration (Plug and play)
• DHCP

IPv6 Features

IPv6 only allows fragmentation in the origin. It does not feature a mechanism equivalent to the Don’t Fragment (DF) bit in IPv4.

A jumbogram is an IPv6 packet that contains a payload higher than 65535 bytes.

IPv6 EUI-65

EUI-65 is an standard published by IEEE that allows a node to autoconfigure or assign automatically its its own IPv6 address. This is done by using the IEEE 802 MAC address of the network card of the own node and the network address prefix /64 to which this node is connected.

You might be also interested in…

• Computer Networks
• IPv4

External references

• “Measuring IPv6“
• Steve’s Internet Guide; “IPv6 explained for beginners“
• Microsoft; “Examine IPv6 addresses“, Microsoft