A client access license (CAL) is needed for each user and device that connects to a Remote Desktop Session (RDS) host. An RDS licensing server is needed 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.
Use the following information to learn about how client access licensing works in Remote Desktop Services and to deploy and manage your licenses:
Understanding the CALs
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 server. |
|
CALs can be tracked regardless of Active Directory membership. |
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 over-allocated. |
CALs can be over-allocated (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.
The following table shows the CALs that are compatible on RD Session Hosts and RD Virtualization Hosts.
|
2000 CAL |
2003 CAL |
2003 R2 CAL |
2008 CAL |
2008 R2 CAL |
2012 CAL |
2016 CAL |
|
|
2000 license server |
Yes |
No |
No |
No |
No |
No |
No |
|
2003 license server |
Yes |
Yes |
Yes |
No |
No |
No |
No |
|
2008, 2008 R2 license server |
Yes |
Yes |
Yes |
Yes |
Yes |
No |
No |
|
2012 license server |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
No |
|
2012 R2 license server |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
No |
|
2016 license server |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
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 2012 R2.