Architecture of the IPv6 Protocol for Windows Server 2008 and Windows Vista

For Windows Server 2008 and Windows Vista, the TCP/IP protocol stack is a dual IP layer implementation, where only a single implementation of the Transport Layer protocols Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) operate over both Internet layer protocols: Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6).

The TCP/IP driver file, Tcpip.sys, contains both IPv4 and IPv6 Internet layers. Tcpip6.sys operates between Windows Sockets and the Network Device Interface Specification (NDIS) layers in the Windows network architecture. The architecture of Tcpip.sys consists of the following layers:

• Transport layer Contains the implementations of TCP and UDP.
• Network layer Contains implementations of both IPv4 and IPv6.
• Framing layer Contains modules that frame IPv4 or IPv6 packets. Modules exist for

IEEE 802.3 (Ethernet), IEEE 802.11, and Point-to-Point Protocol (PPP) links. Modules also exist for logical interfaces such as the loopback interface and IPv4-based tunnels. IPv4-based tunnels are commonly used for IPv6 transition technologies. The IPv4 Internet layer appears as the Internet Protocol Version 4 (TCP/IPv4) component in the list of protocols from the properties of a local area network (LAN) connection in the Network Connections folder. The IPv6 Internet layer appears as the Internet Protocol Version 6 (TCP/IPv6) component. You can enable or disable these components per connection in the Network Connections folder, but you cannot uninstall them. You can uninstall the IPv4 Internet layer with the netsh interface ipv4 uninstall command, but you cannot uninstall the IPv6 Internet layer.

Source of Information : Microsoft Press Understanding IPv6 2nd Edition