15.3.3 IPv6 Addressing

IPv6 was developed to overcome the addressing limitations of IPv4 while simplifying several aspects of Internet operation. The most obvious change is the increase in address size from 32 bits to 128 bits, providing an address space so large that it is effectively inexhaustible for the foreseeable future.

IPv6 addresses are written as eight groups of four hexadecimal digits separated by colons. For example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

Because long sequences of zeros occur frequently, IPv6 allows these to be abbreviated using standardized notation, making addresses easier to read and write.

The greatly expanded address space allows generous address allocation, simplifying network planning while eliminating the need for many of the address-conservation techniques required by IPv4. It also supports the continued growth of cloud computing, mobile communications, and the Internet of Things.

Beyond its larger address space, IPv6 incorporates several architectural improvements, including:

a simplified packet header;
more efficient packet forwarding;
improved support for automatic address configuration;
integrated support for modern security mechanisms; and
better scalability for future Internet growth.

Although IPv4 and IPv6 use different address formats, they perform the same fundamental function—providing logical addresses that allow routers to deliver packets across interconnected networks.