Ipv6

DirectAccess uses IPv6 to enable client computers to maintain constant end-to-end connectivity with remote intranet resources over a public Internet connection. Because most of the public Internet currently uses IPv4, however, DirectAccess can use IPv6 transition technologies such as Teredo and 6to4 to provide IPv6 connectivity over the IPv4 Internet. The preferred connectivity method for the client computer depends on the type of IP address assigned to the client. Specifically:

• If the client is assigned a globally routable IPv6 address, the preferred connectivity method is to use this address.
• If the client is assigned a public IPv4 address, the preferred connectivity method is to use 6to4.
• If the client is assigned a private (NAT) IPv4 address, the preferred connectivity method is to use Teredo.
• If the client is assigned a private (NAT) IPv4 address and the NAT device also provides 6to4 gateway functionality, 6to4 will be used.

If none of these connectivity methods can be used in a particular scenario, DirectAccess can also use IP-HTTPS, a new protocol developed by Microsoft for Windows 7 and Windows Server 2008 R2, which enables hosts located behind a Web proxy server or firewall to establish connectivity by tunneling IPv6 packets inside an IPv4-based HTTPS session.

For remote client computers to use DirectAccess to connect to computers on the internal corporate network, these computers and their applications must be reachable over IPv6. This means the following:

• The internal computers and the applications running on them support IPv6. Computers running Windows 7, Windows Vista, Windows Server 2008, or Windows Server 2008 R2 support IPv6 and have IPv6 enabled by default.
• You have deployed native IPv6 connectivity or Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) on your intranet. ISATAP allows your internal servers and applications to be reachable by tunneling IPv6 traffic over your IPv4-only intranet.

For computers and applications that do not support IPv6, you can use a Network Address Translation-Protocol Translation (NAT-PT) device to translate IPv6 and IPv4 traffic. Microsoft recommends using IPv6-capable computers and applications and native IPv6 or ISATAP-based connectivity over the use of NAT-PT devices.