Deciding the licensing model…
Once you have this ‘Picasso’ (your visualisation) on a wall in your ‘think tank’, start using post it notes to interact with the detail. Microsoft has come up with a defined set of modeld, which I have tried to depict here:
Server Licence and Client Access Licenses (CAL’s)
Here you purchase a server license for each server and then purchase a CAL for either users or devices. A device CAL is assigned to the device and allows multiple users to use that device. A user CAL is assigned to the user and allows that user to use multiple devices.
Applies to: Microsoft Windows Server 2008 R2 and Microsoft Exchange server 2010
Standard and Enterprise CAL’s
Some server products offer different levels of functionality that can be exposed to users or devices, and there are CALs that correspond to this functionality. If the extended functionality is utilised then the purchase of an Enterprise CAL is required in addition to the Standard CAL.
Applies to: Microsoft Sharepoint 2010, Exchange server 2010 and Lync Server 2010.
In some instances it can be more effective for organisations to purchase their CALs in suites. These 2 suites are known as Core CAL suite and Enterprise CAL suites.
This lets you to license the server or serves that will be accessed by external users, but they must use the dame feature sets.
Here you need to purchase a license per processor in your physical servers. It then allows all external and internal access to that server with no need for CALs.
Applies to: Microsoft SQL Server 2008 R2, BizTalk Server 2010
Here licensing is managed for a Management Server, which has its own license. Then a client device requires Client Management Licenses and managed servers require either a Standard Server Management License (ML), depending on what’s running.
Points for Consideration
There are many ways you can decide on the best model for you, and the key is to ensure that run scenarios. Remember that everyone OS requires its own server license, so the more servers the more licensing required. Standard and Enterprise CALs can also be used to license External Users.