Chapter #1 – Address Format
IPv6 addresses are quite different to IPv4. They use hexadecimal numbers, rather than decimal. There are also eight groups of numbers, rather than four. Each group is separated by colon characters.
Chapter #2 – Making it Simpler
IPv6 addresses can be simplified. The first step is to omit any leading zeroes in a group. Then, if there are several groups of zeroes in a row, they can be replaced by a double colon. This can only be done once though.
Chapter #3 – Subnets and Prefixes
The network portion of an IPv6 address is called a prefix. This is the same as a subnet in IPv4.
Subnet masks are now called the prefix length. They are only written in CIDR notation now, not dotted decimal. A /64 prefix is the most commonly used prefix now. However, other sizes are still ok, such as /127 for a point-to-point WAN.
Chapter #4 – Header Format
IPv6 has a larger header, as it has larger source and destination IP addresses. Even so, it’s much simpler.