Classification of IPv6-Only Networks by Levels

IPv6-only networking is recognized as the ultimate goal of network evolution. However, in practice, the understanding and implementation of IPv6-only varies significantly. To address ambiguity and improve communication, this document proposes a classification for IPv6-only networks. It defines three distinct levels, from a pure state with no IPv4 support to scenarios where IPv6-only and dual-stack coexistence exists. This approach of classification is applicable to all network scenarios and aids operators and protocol designers in precisely specifying the nature of their IPv6-only deployments.