[This is the 2nd part in the sequel. You can find part 1 here.]

We talked about licensing Windows Server on a VMware environment but that’s only one part of the licensing nightmare. You will also need client access licenses also called CALs.

Client Access Licensing

In addition of the Windows Server 2008 License you also need a Windows Server 2008 Client Access License also called CAL. This is required for each user or device (or combination of both) that accesses or uses the Windows 2008 software.


Every user or device accessing the Windows Server 2008 needs a CAL. You don’t need a CAL when:

  • You access the instance of server software only through the internet without being authenticated or individually identified by the server software;
  • You access Windows Web Server 2008;
  • If external users are accessing the instances of server software and you have acquired a Windows Server 2008 External Connector License for each server being accessed;
  • You only administer the server software with two devices or users;
  • You use the Windows Server 2008 solely as a virtualization host.

The last point doesn’t impact us much because we use VMware ESXi solely as our virtualization platform.

How to choose the correct CAL licensing?

Step 1 – Choose your CAL type: Device CAL or User CAL

You can choose between two types of Windows CALs: device-based (Device CALs) or user-based (Windows User CALs).

With a device-CAL you access the network and the Windows Server 2008 resources from a device which might be used by multiple users. For every device which accesses the network you need a device CAL.

With a user-CAL one user uses multiple devices to access the resources on the network for every user in the organization that accesses the network you will need a user-CAL license.

Step 2 – Choose your Client Access Licensing Mode: Per User/Per Device Mode or Per Server mode

After choosing a user-based or device-based license you have the option to use the server software in two different modes: Per User/Per Device mode or Per Server mode. Both modes are available for either type of license.

Per User/Per Device mode

This mode is the mode where 1 user may access several servers, it replaces the Per Seat mode found in older versions of Windows.  (99.9% of the customers run the software in this mode)

Per Server mode

In this mode you need a CAL for every user/device who accesses a server. So if you have multiple servers you need per user/device a CAL for every server accessed.

Now that we have the Server licenses and the different forms let’s try an example.


An organization uses 3 VMware vSphere 4 ESXi servers, with 2 Six Core CPUs per server to host 60 Windows 2008 and 5 Windows 2003 virtual machines. These machines are accessed by 2500 Internet users without being authenticated, 1200 employees who work in 3 – 8 hour shifts on about 2000  different devices.

What licensing do we need here?

6 Windows Server 2008 Datacenter licenses  and 1200 Windows User CALs (user based licenses) and the servers in per user/per device mode.

If you deploy Windows Server 2003 virtual machines onto VMware ESXi, you do not require Windows Server 2008 CALs for your virtual machine users. (You will still require CALs for your appropriate Windows Server edition, in this case, for Windows Server 2003), because of the server mode and the CALs best be user-based you already have the appropriate licenses for the Windows 2003 servers if you bought new ones for the Windows 2008 servers.

Do we need a CAL or an External Connector License?

Core CAL Suites

We discussed the basic CALs you need when running Windows virtual machines in a VMware environment, but inside the virtual machines we tend to run Microsoft applications like: Exchange, SQL, Sharepoint, OCS, System Center and Forefront. For each of these applications you also need a CAL besides the server side of the licensing.

There are a lot of different CALs and types out there; some are combined in suites but also exclusively available.  The suites can only be purchased through volume licensing.

The Core CAL includes CALs for:

  • Microsoft Windows Server
  • Microsoft Exchange Server
  • Microsoft Systems Management Server
  • Microsoft SharePoint Portal Server

For SQL Server you can also buy a processor license instead of CALs. For System Center you buy Management Server CALs. With the Enterprise CAL Suite you get more options on top of the Core CAL suite.

What types of CALs are out there?

As you can see there are a lot of flavors and different CALs out there, some we mentioned are:

  • Windows User CAL
  • Device CAL
  • TS CAL (Terminal Services)
  • RDS CAL (Remote Desktop Services)
  • Per Processor CAL
  • Management Server CAL
  • Core CAL (Suite)
  • Enterprise CAL (Suite)
  • VECD

CAL Suites

  • Core CAL Suite
  • Enterprise CAL Suite

Because CAL Suites contain licenses to products that are released independently, CAL Suites are version-less. CAL Suites are only offered with Software Assurance coverage, and accordingly give customers the right to use the most recent version of every product in the suite.

All Enterprise CAL Suite components are available for individual purchase also. For more information around licensing the core CAL and Enterprise Suite follow this link.


Either VECD or VECD for SA is required for any VDI environment running Windows as the guest operating system, regardless of the choice of infrastructure or hypervisor vendor that the customer chooses. More information about the VECD license can be found at the following link.

CAL Tracking

Because of all the different CALs and software licenses it becomes hard too find out which software you use and which license you will need, Microsoft made a tool called the MAP Toolkit to help us track which software is used in the environment so we get a picture of what licenses we should get to get compliant with the terms and conditions.

The Microsoft Assessment and Planning (MAP) Toolkit is an agentless tool designed to simplify and streamline the IT infrastructure planning process across multiple scenarios through network-wide automated discovery and assessments. MAP performs an inventory of heterogeneous IT environments and provides you with usage information for SQL Server and servers in the Core CAL Suite.

The Microsoft Assessment and Planning (MAP) Toolkit 5.0 includes the following new features for simplified IT infrastructure planning:

  • Heterogeneous IT environment inventory
  • Software usage tracking for Windows Server, SharePoint Server, System Center Configuration Manager, Exchange Server, and SQL Server
  • Microsoft Office 2010 readiness assessment
  • SQL Server discovery and assessment for consolidation
  • Windows 2000 migration assessment

You can use this toolkit to track the use of Windows Server and several Microsoft applications like Sharepoint, SCCM , Exchange Server and SQL Server.

For an in depth guide to assessing Windows Server Licensing use this guide.