Global Unicast Addressing, Routing, and Subnetting: This section introduces the concepts behind unicast IPv6 addresses, IPv6 routing, and subnetting using IPv6, all in comparison to IPv4. IPv6 ...
One glaring problem with IPv4 is that it supports only 4.2 billion possible addresses while, by some estimates, the number of internet-connected devices is expected to grow to 28.5 billion by 2022.