This report considers the transition from IPv4 to IPv6 alongside the use of network technologies to prolong IPv4 use in the face of depletion of further IPv4 protocol addresses, but it does not aim to address all issues surrounding the transition to IPv6 or to detail the economic incentives faced by various Internet actors. It first provides a status update of address management issues and the run-out of IPv4. It then describes the advantages and limitations of increased use of network address translation as one response to sustain the use of IPv4 in the face of IPv4 address exhaustion. It provides an overview of the IPv6 protocol; the advantages of IPv6 deployment as a response to IPv4 address exhaustion and the IPv6 transition plan compared to actual deployment to date. Finally, the report examines the choices facing individual actors, their potential consequences, and the policy implications on openness and innovation for the future of the Internet.