The fundamental difference between IPv4 and IPv6 addressing lies in their size and how addresses are assigned to each host.

While IPv4 uses 32-bit addresses, limiting the address space to approximately 4.3 billion unique addresses, IPv6 uses 128-bit addresses, offering virtually unlimited space for unique addresses.

This expansion in address space allows for more granular, flexible, and efficient address allocation. Let's see how the address assignment methods in IPv6 differ:

IPv6 Address Structure

An IPv6 address is made up of 128 bits, typically represented as 8 groups of 4 hexadecimal digits. This structure allows for a large number of unique addresses, enough to assign billions of addresses to every grain of sand on Earth.

Unique Local Addresses (ULAs)

In a private network environment, IPv6 uses Unique Local Addresses (ULAs) which are analogous to private addresses in IPv4 (such as addresses beginning with 192.168., 10., and 172.16. to 172.31.). ULAs in IPv6 are designed to be used internally within private networks and are not routable on the Internet. They offer a large address space to assign to devices without the risk of global address conflicts.

Stateless Autoconfiguration (SLAAC)

IPv6 introduces Stateless Address AutoConfiguration (SLAAC), which allows devices on a network to automatically obtain unique addresses without the need for a DHCP server. Each device generates its own address using the network prefix provided by the router and its own identifier, usually derived from the device's MAC address. This ensures that each host on a network has a unique address.

Autoconfiguration with State

Through DHCPv6, IPv6 also supports stateful autoconfiguration, similar to DHCP in IPv4, where a DHCP server assigns specific addresses to devices on a network. This is useful for network administrators who need control over assigned IP addresses.

Huge Address Space

The massive number of addresses available in IPv6 eliminates the need for techniques such as NAT (Network Address Translation), allowing each device to have a globally unique address, simplifying network configurations and improving network security and efficiency. .

In summary, addressing in IPv6 differs from IPv4 in its ability to provide a nearly unlimited number of unique addresses directly to devices, enabling self-configuration of hosts, reducing the need for address management, and significantly simplifying the architecture of global network.