Welcome to ELVInfra, This article provides an overview of the Remote Desktop Protocol (RDP) and its role in facilitating communication between the Terminal Server and the Terminal Server Client. RDP operates within the framework of TCP and is designed to ensure secure and encapsulated communication. Key Details: RDP is an extension of the T-120 family of protocol standards, enabling the establishment of multiple virtual channels for distinct purposes. These channels are dedicated to various types of data, including presentation data, serial device communication, licensing information, and highly encrypted data, such as keyboard and mouse activity. The underlying architecture of RDP maintains features necessary to support multipoint (multiparty sessions), allowing real-time data delivery to multiple recipients. For example, it facilitates Virtual Whiteboards where data is shared among participants without the need to transmit the same data to each session individually. In its initial release with Windows Terminal Server 4.0, the focus is primarily on providing reliable and fast point-to-point (single-session) communication. This release utilizes a single data channel. However, RDP's flexibility provides room for expanding its functionality in future products. Microsoft adopted RDP within Windows NT Terminal Server to create a foundation for building additional capabilities. RDP offers 64,000 separate channels for data transmission, although the current transmission activities primarily use a single channel for keyboard, mouse, and presentation data. RDP is designed to accommodate various network topologies, including ISDN and POTS, as well as LAN protocols such as IPX, NetBIOS, and TCP/IP. The present version of RDP exclusively runs over TCP/IP, with the potential for future versions to support other protocols based on customer feedback. Data transmission through the RDP stack follows a process that aligns with the seven-layer OSI model for common LAN networking. It involves segmentation, encryption, wrapping, framing, channel assignment through MCS (Multipoint Communication Service), and prioritization before being sent over the network to the client. An essential point for application developers is that RDP abstracts the complexities of dealing with the protocol stack, allowing developers to focus on creating clean and well-behaved 32-bit applications. The RDP stack, implemented by the Terminal Server and its client connections, handles the rest. Four key components within the RDP stack instance are the Multipoint Communication Service (MCSMUX), Generic Conference Control (GCC), Wdtshare.sys, and Tdtcp.sys. MCSMUX and GCC are part of the ITU T.120 family, with MCSMUX responsible for multiplexing data onto virtual channels and controlling priority levels, while GCC manages session connections and resources provided by MCS. RDP's architecture is transport-independent, making it adaptable to various network protocols. The architecture includes RDP driver (Wdtshare.sys) for UI transfer, compression, encryption, and framing, as well as a transport driver (Tdtcp.sys) for packaging the protocol onto the underlying network protocol (TCP/IP). This design allows for adding other transport drivers to support additional network protocols with minimal changes to the core protocol, enhancing performance and extensibility.