Q: What is Enhanced Session Mode in Windows Server 2012 R2 Hyper-V?

A: One change in Windows Server 2012 R2 for virtual machines (VMs) is that the Remote Desktop Connection can now integrate with the VMBus, which is used between a VM and the parent partition. This enables VM connections (via Hyper-V Manager or via VMConnect.exe) to leverage functionality traditionally associated with RDP connections, including:

  • Rich display
  • Audio
  • Printers
  • Clipboard
  • USB devices
  • Drives
  • Plug and play devices
  • Smart cards

The requirements that need to be met are as follows:

  • Guest OS in the VM supports remote desktop services (e.g., Windows 8.1 Pro/Enterprise/Windows Server 2012 R2)
  • The server policy in Hyper-V Manager server settings for Enhanced Session Mode is enabled (Enhanced Session Mode Policy, Allow enhanced session mode.) It's disabled by default.
  • Remote Desktop Services service is running in the guest (but the Allow remote connections to this computer in System configuration doesn't need to be enabled).
  • User logging on is as a member of local administrators or remote desktop users in the guest.
  • Out Of Box Experience (OOBE) has been completed.

When you connect to a VM that supports ESM, an initial dialog allows configuration of display and local resources redirected in addition to letting you save the configuration. Any saved configurations are written to %APPDATA%\Roaming\Microsoft\Windows\Hyper-V\Client\1.0 with a name format of vmconnect.rdp..config.

Note that this is considered an administrative connection, so the RDS CAL isn't required.