IPv6 and IPv4 will coexist for many years, and there are a wide range of techniques that make coexistence possible and provide an easy transition. These techniques are separated into three main categories:
These techniques can and likely will be used in combination with one another. The migration to IPv6 can be done step-by-step, starting with a single host or subnet. You can migrate your corporate network or parts of it while your ISP still runs only IPv4, or your ISP can upgrade to IPv6 while your corporate network still runs IPv4. This chapter describes the techniques available today for each of these categories. RFC 4213, "Basic Transition Mechanisms for IPv6 Hosts and Routers," describes the dual-stack technique and configured tunneling. As IPv6 grows into our networks, there will be new tools and mechanisms to ease the transition further.