TCP/IP v4 and v6
Windows Server 2008 and Windows Vista TCP/IP was completely redesigned to support both Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) to meet the connectivity and performance needs of today's varied networking environments and technologies.
These protocols provide IP addresses, the "phone numbers" for the Internet that are responsible for identifying computers and devices so that they can communicate.
IPv6 is designed to solve many of the problems of IPv4, including mobility, auto-configuration, and overall extensibility. IPv6 expands the address space on the Internet and supports a nearly unlimited number of devices that can be directly connected to the Internet.