by Greg Shields

Later, in Parts 22 through 24, I’ll talk more about the actual installation and configuration of licenses for your Terminal Servers. However, at this point, it is important to know that extra licensing will be required for you to use Terminal Services in your environment. These extra Terminal Server Client Access Licenses (TSCALs) are required by each user or device that connects to your Terminal Server.

TSCALs are a separate license than the standard Client Access Licenses (CALs) you have likely already purchased for clients in your environment. Standard CALs are used for each client who requires access to a Windows server. The use of Terminal Services requires you to purchase and install TSCALs in addition to CALs for clients who will use Terminal Services. Another important distinction is that TSCALs are required only for clients who connect via Terminal Services and not for those who use an administrative connection via Remote Desktop.

When considering the purchase of TSCALs for your Terminal Services environment, you will have two options for how to purchase and manage these licenses: Per User and Per Device. The distinction between these two licensing models is important based on the ways in which you plan for your users to connect to your Terminal Servers. Per User TSCALs require the use of one license for every user who will connect into a Terminal Server farm. Per Device TSCALs are linked to the specific devices-laptops, desktops, thin clients, and so on-that are used to connect into the environment. Per Device TSCALs are different in that there is no limit to the number of users who can be licensed on the same device.

The majority of environments tend to use Per User TSCALs. This is the case because in most environments individual computers are assigned to a single user, with few cases where multiple users share computers. In this situation, the use of Per User TSCALs makes the administration of licenses easy for the administrator because the number of licenses simply equals the number of connecting users.

Conversely, in environments where many users share the use of a smaller number of computers, choosing Per Device licensing can be advantageous. In this case, licenses can be purchased for each connecting device, irrespective of the number of users who use that device.

The decision regarding which type of licenses in your environment will be an architectural one that is based on the usage patterns of your users. If your users tend to stick with the same computer throughout the day, the use of Per User licenses is likely to be easiest and cheapest. This model means that the same user who connects at their desk at the office can connect via a VPN or other mechanism without needing additional licensing. However, if your count of users is higher than your number of devices, the Per Device model is likely to require the purchase of fewer TSCALs.

About the Author

Greg Shields is an independent author, speaker, and IT consultant, as well as a Partner and Principal Technologist with Concentrated Technology. With 15 years in information technology, Greg has developed extensive experience in systems administration, engineering, and architecture specializing in Microsoft OS, remote application, systems management, and virtualization technologies. He is a Contributing Editor and columnist for TechNet Magazine and Redmond Magazine, and serves as the Series Editor for Realtime Publishers, the world’s leading provider of high-quality content for the IT market. Greg is a highly sought-after and top-ranked speaker for both live and recorded events, and is seen regularly at conferences like TechMentor Events, Microsoft Tech Ed, VMworld, and more. He is a multiple recipient of Microsoft “Most Valuable Professional” award.