In Windows Server 2008 R2, Remote Desktop Session Host server, formerly known as Terminal Server, supports per-session and per-program Remote Desktop IP Virtualization for Winsock applications. This essentially means assigning individual IP addresses to user sessions to avoid application incompatibility issues by simulating a single user desktop. Prerequisites for configuring a server in RD IP Virtualization mode: Ensure that there are no active sessions on the RD Session Host server before enabling this feature, Ensure that the DHCP server is set on the same subnet as the RD Session Host server and that the DHCP scope contains enough IP addresses for the load.

Full Article: RDS Blog