In understanding the RAS architecture, it is important to make the distinction between RAS and remote control solutions, such as Cubix and pcANYWHERE. RAS is a software-based multi-protocol router; remote control solutions work by sharing screen, keyboard and mouse over the wire. In a remote control solution, users share a CPU or multiple CPU's on the server. The RAS server's CPU is dedicated to communications, not to running applications.
This architectural difference has significant implications in two areas: scalability and software applications architecture.
In the area of scalability, consider the differing approach to increasing the capacity or performance of a remote-control server. For best performance, an additional or upgraded CPU or computer would need to be purchased for every port to be added or upgraded. With RAS, additional ports can be added without upgrading the server computer. When it does require an upgrade, the RAS Server would generally get additional RAM, a less costly approach than with remote-control. With Windows NT, a single server can scale to support hundreds of remote users, using far fewer hardware resources than a remote control solution.
In software applications architecture, the RAS client normally executes applications from the remote workstation. Contrast this with the remote control client, which runs applications from the host-side CPU. The RAS arrangement is better suited to graphical, client-server¾based applications, and because network traffic is reduced, the user achieves higher performance. Remote control, however, can be useful in non-client-server environments.