Internet Protocol version 6 (IPv6) is the new version of the network layer of the TCP/IP protocol stack, and is designed to replace IPv4 which is widely used on intranets and the Internet. IPv6 provides an address space large enough to allow for end-to-end addressing of nodes on the IPv6 Internet, and can be used on the IPv4 Internet with IPv6 transition technologies.
Forefront UAG DirectAccess requires the use of IPv6 so that DirectAccess clients have globally routable addresses. For organizations that are already using a native IPv6 infrastructure, Forefront UAG DirectAccess seamlessly extends the existing infrastructure to DirectAccess client computers, and these client computers can still access Internet resources using IPv4. For organizations that have not yet begun deploying IPv6, Forefront UAG DirectAccess uses IPv6 transition technologies to provide a way to begin IPv6 deployment without requiring an infrastructure upgrade. You can use these transition technologies so that DirectAccess clients can access IPv6-capable resources across your IPv4-only intranet, thus simplifying and reducing deployment costs. For more information, see Using transition technologies.