[0x21] A short introduction to IPv6

Good day!

IPv6 is described in detail in RFC 1884, The IP Version 6 Addressing Architecture. IPv6 is commonly called as "Next Generation Internet Addressing System".

Why IPv6?
Basically the Internet started running out of IPv4 addresses back in the mid 1990s. We've outgrown IPv4. IPv4 had some shortcomings that became obvious once the internet had grown in substantially in size and complexity. The main factor was that IPv4 used 32-bit address size, whereas IPv6 can allocate 128-bit addresses.

IPv6 address representation is much like that of IPv4, because the address are represented in strings of digits divided by separators, but IPv6 addresses differ in that they take the form nn:nn:nn:nn:nn:nn:nn:nn, where each `nn` represents the hexadecimal form of 16 bits of address. IPv6 also differs in more complex ways, but this is just an introduction. For the full details see RFC 1884 or wiki information IPv6 wiki.

IPv6 has identified 3 types of address, these are unicast, multicast and anycast.

    Unicast:   An identifier for a single interface.  A packet sent to a
               unicast address is delivered to the interface identified
               by that address.

    Anycast:   An identifier for a set of interfaces (typically
               belonging to different nodes).  A packet sent to an
               anycast address is delivered to one of the interfaces
               identified by that address (the "nearest" one, according
               to the routing protocols' measure of distance).

    Multicast: An identifier for a set of interfaces (typically
               belonging to different nodes).  A packet sent to a
               multicast address is delivered to all interfaces
               identified by that address.

For more information about these types, then read RFC 1884

So in summary, IPv6 offers a more permanent solution for flexible address space as well as support for accessing the public internet and private IP-based networks from existing corporate and enterprise LAN's and WAN's.