IPv6 was introduced to expand IPv4’s lacking address space.

Fun Trivia

IPv5 was an experimental protocol that introduced the concept of connections.

Was never widely adopted and connection state was handled better later on by transport layer and TCP.

IPv4 address uses 32 bit

IPv6 address uses 128 bit

Example of IPv6 address

Rule to shortening IPv6 address

• leading zeros can be removed
• if all zeros = replaced with two colons (::). Can only happen once for any specific address

and finally 2001:db8::ff00:12:3456

Loop back address

loop back address in IPv4 is 127.0.0.1 and in IPv6 all zero except one 1, which can be condensed down to just ::1

Special addresses

FF00: multi-cast

FE80: link-local unicast

Link-local unicast addresses