Windows Server RDS CALs
License your RDS deployment with Client Access Licenses (CALs)
Each user and device that connects to a Remote Desktop Session host needs a client access licenses (CAL). You use RD Licensing to install, issue, and track RDS CALs. When a user or a device connects to an RD Session Host server, the RD Session Host server determines if an RDS CAL is needed. The RD Session Host server then requests an RDS CAL from the Remote Desktop license server. If an appropriate RDS CAL is available from a license server, the RDS CAL is issued to the client, and the client is able to connect to the RD Session
Host server and from there to the desktop or apps they're trying to use. Although there is a licensing grace period during which no license server is required, after the grace period ends, clients must have a valid RDS CAL issued by a license server before they can log on to an RD Session Host server. Use the following information to learn about how client access licensing works in Remote Desktop Services and to deployand manage your licenses:
Understanding the CALs model
There are two types of CALs:
- RDS Per Device CALs
- RDS Per User CALs
The following table outlines the differences between the two types of CALs:
|Per Device||Per User|
|CALs are physically assigned to each device.||CALs are assigned to a user in Active Directory.|
|CALs are tracked and enforced by the license server.||CALs are tracked but not enforced by the license
|CALs can be tracked regardless of Active Directory
|CALs cannot be tracked within a workgroup.|
|You can revoke up to 20% of CALs.||You cannot revoke any CALs.|
|Temporary CALs are valid for 52-89 days.||Temporary CALs are not available.|
|CALs cannot be overallocated.||CALs can be overallocated (in breach of the Remote
Desktop licensing agreement).
Note about CAL versions
The CAL used by users or devices must correspond to the version of Windows Server that the user or device is connecting to. You can't use older CALs to access newer Windows Server versions, but you can use newer CALs to access older Windows Server versions
Any RDS license server can host licenses from all previous versions of Remote Desktop Services and the current version of Remote Desktop Services.
For example, a Windows Server 2016 RDS license server can host licenses from all previous versions of RDS, while a Windows Server 2012 R2 RDS license server can only host licenses up to Windows Server 2012R2.