Terminal Services Virtual Channels (used by MMR)

Virtual channels are software extensions that can be used to add functional enhancements to a Terminal Services application. Examples of functional enhancements might include: support for special types of hardware, audio, or other additions to the core functionality provided by the Terminal Services Remote Desktop Protocol (RDP). The RDP protocol provides multiplexed management of multiple virtual channels.

A virtual channel application has two parts, a client-side component and a server-side component. The server-side component is an executable program running on the terminal server. The client-side component is a DLL that must be loaded into memory on the client computer when the Terminal Services client program runs.

Virtual channels can add functional enhancements to a Terminal Services client, independent of the RDP protocol. With virtual channel support, new features can be added without having to update the client or server software, or the RDP protocol.

Four major classes of users of virtual channels have been identified:

• General kernel-mode drivers, such as serial or printer drivers.
• File system redirection (this is just a special case of a general kernel-mode driver).
• User mode applications, for example remote cut-and-paste.
• Audio devices.

For more information, see Using Terminal Services Virtual Channels.

If you have enabled a virtual channels application in your Terminal Services deployment, you can make the application available to client computers that access the terminal server by means of the Remote Desktop Microsoft ActiveX control. For more information, see Scriptable Virtual Channels and Using the Remote Desktop ActiveX Control with Virtual Channels.

General Installation Guidelines VDI

The following guidelines apply to all installations types (new installations and upgrades).

• Synchronize time — Make sure that you have synchronized time across VDM Connection Server and desktop virtual machines. By default, virtual machines pick up the time from the ESX host at boot up and you may have to synchronize time on the ESX hosts through the ntpd service.
• Validate your Internet Explorer settings — VDM Client uses Microsoft Internet Explorer� internet settings, including proxy settings, when connecting to VDM Connection Server. Ensure that your Internet Explorer settings are accurate and that you can access the VDM Connection Server URL through Internet Explorer.
• Before creating an automatically provisioned desktop pool, do the following:
  • Validate the VirtualCenter guest customization specification if you intend to use one — Make sure that the guest customization specification in VirtualCenter is accurate. You should use VirtualCenter to deploy and customize a VM from your template using that customization specification and fully test the resulting VM (in other words, DHCP, authentication) before using that customization specification in VDM Administrator.
  • Validate network ports on ESX — Make sure you have a sufficient number of ports on the virtual switch which is used for the guest VMs. The default value for ESX server is 24; it may not be sufficient when creating a large pool of desktop VMs.
• Install required Microsoft Windows patches — For Windows XP desktop VMs, make sure you have RDP patches referenced by Microsoft Knowledge Base (KB) articles 323497 and 884020. Failure to do this may result in a Windows Sockets failed error message on the client. You can find these KB articles at the following URLs:
  • http://support.microsoft.com/kb/323497
  • http://support.microsoft.com/kb/884020
• It is recommended that you upgrade VDM Client machines to use Microsoft Remote Desktop Connection (RDC) 6.0 — This recommendation applies to machines running Windows XP and Windows XPe. Windows 2000 does not support RDC 6.0.Windows Vista comes with RDC 6.0 installed.RDC 6.0 can be downloaded at the following Microsoft download site: Microsoft downloads
• VDM does not support using link-local (169.254.x.x) addresses for desktop virtual machines — Configure desktop virtual machines to use DHCP or static IP addresses.

VDM 2.1 what’s new and what are the issues

VDM 2.1 includes the following improvements and new features

• Pools spanning datastores in order to better manage resources
• Localization of VDM Web Access and Client for Windows in Japanese and German
• Command line parameters for VDM Client
• Integrate MMR multimedia extensions DLL with VDM Client (Windows XP)
• Allow end users to change password
• Multiple sessions per user within a pool
• Improvements to logging
• Allow end users to restart their VM
• Defined process for bulk import of individual desktops
• VDM Configuration Backup (command-line only)
• Allow blocking of incoming RDP connections that are not from VDM Clients
• Allow VDM administrators to set default desktop (command line only)

The latest advancements in Virtual Desktop Manager 2.1 include:

• Improved Scalability: VMware Virtual Desktop Manager 2.1 can run up to 5,000 concurrent connections per cluster of Virtual Desktop Manager servers and provides enterprises the ability to scale to tens of thousands of desktop connections through the use of multiple clusters. In addition, VMware Virtual Desktop Manager enables hundreds of desktop virtual machines to be created in a single storage pool. This enhancement gives customers unparalleled scalability to extend investments in their storage systems.
• Enhanced End User Experience: VMware Virtual Desktop Manager 2.1 offers a new multi-media redirection feature for XP desktops. This feature redirects certain multi-media codecs to the local PC for rendering of full-motion video and audio.
• Improved manageability: VMware Virtual Desktop Manager 2.1 features a new transaction logging capability for improved management.
• Expanded Support for Global Organizations: Localized versions are now available in German and Japanese, to accelerate user adoption in global organizations.

Known issues fixed in VDM 2.1

• The VDM Administrator user interface can only be accessed through a VDM Connection Server in a standard or replica installation (1003766)
• When creating or editing desktops, Vista desktops do not show up in the list (1003767)
• VDM Administrator user interface does not allow you to enter the license key (100376
• VDM Client allows a user to change the desktop preferences after a session timeout (1003775)
• Administrative rights requirement for use of VDM USB Driver (1003776)
• The VDM Connection Server has a known issue which may affect the uptime of a deployed server (1003784)

Known Issues and Restrictions in VDM 2.1

The following are known issues and restrictions for VMware VDM 2.1. The items listed in this section are links to Knowledge Base articles.

VDM Administrator

• On the desktop summary page, the value selected for Do not power on virtual machine after creation does not display correctly. The policy follows what has been selected in the desktop wizard. (1005390)
• When you remove a user’s entitlement, the user will not automatically be logged off. Make sure they have no connections remaining to that pool. (1005403)
• In a non-persistent desktop pool, when decreasing pool size, it may take longer than expected to delete virtual machines. (1005433)
• Image customization specifications in VirtualCenter must have a NIC configured in order to create a desktop pool. (1005392)
• The error message “insufficient disk space” may mean that there is a network connectivity problem and not a lack of disk space. (1005385)
• A “General fault caused by file” error message is generated when a “Insufficient space for provisioning operation” error message should be generated. (1005564)
• In VirtualCenter, deleting a virtual machine that is in the cloning state does not remove the VDM configuration entry. No new attempt to clone the virtual machine will be initiated. (1005371)
• Japanese characters in external URLs do not display correctly (1005804)

VDM Connection Server

• VDM Connection Server must be installed in directories with ASCII characters only. (1005352)
• If your external URL is not configured correctly, you may see one of the following exception: java.io.IOException:readToken:Premature EOF in the log file. (1005377)
• When using a thin client and manually entering a domain name, the name must be entered in upper case letters for SSO to function. (1005381)
• When setting the default desktop on the command prompt, you must enter both domain name and username. (1005382)
• The name of a VDM Server in a Japanese domain cannot be resolved by a Windows Vista VDM Client. (1005393)
• If the installation path for a VDM Connection Server contains special characters, the VDM Connection Server service stops or will not start. (1005454)
• Extended logging and Disk threshold for logging GPO policies are not component specific. (1005461)
• When an ESX host and associated virtual machines are removed from VirtualCenter, VDM removes those virtual machines that are powered off or suspended from the VDM directory. (1005484)
• Broker cannot distinguish between original and cloned virtual machines (1003785)

VDM Web Access

• Support for VDM Web Access with Mac OS is experimental (1003769)
• Linux Web Access usernames cannot cannot begin with a hyphen (1003771)
• When closing your browser or browser session while using VDM Web Access it can take up to two minutes for the session to reset. (100543
• User names with more than 20 characters are not supported by VDM Web Access. (1005449)
• Web Access on Windows does not support accessing VDM servers with localized domain names. (1005452)

VDM Client

• After acknowledging the pre-login message, leaving the client on the login screen without any activity for several minutes causes the login process to stall. (1005386)
• A Windows Security Alert message may be issued by the firewall the first time VDM Client or VDM Web Access on Windows is used (1003773)
• Session timeout produces unexpected behavior when the Direct Connect to Virtual Desktop option is enabled(1003774)
• VDM client unable to connect when Citrix XenDesktop or Citrix Desktop Server agent is installed on VDM agent desktop (1005353)
• MMR requires overlay support. (1005560)

USB Redirection

The USB redirection feature of VDM Client provides generic support for redirecting locally attached USB devices to the desktop virtual machine. The feature has been successfully tested with a range of devices, including printers, scanners, mass storage devices, phones and PDAs. See the KB article at the following URL for details about known issues with redirecting specific USB devices in VDM http://www.vmware.com/info?id=346 .

• Apple iTouch does not fully synchronize from a USB hard drive. (1005379)
• Some Human Interface Devices may appear in the VDM Client Devices menu. Devices that are required for local usage (such as keyboards and mice) should not be shared to the Guest virtual machine. (1005451)
• USB Redirection Administrative Privileges (1003776)
• Webcams have known issues with USB redirection and are not supported. (1003777)
• Some composite (multi-function devices) will appear in the device list as more than one device (100377
• In general, Bluetooth devices are shareable to the VMware VDM session and devices attached via the Bluetooth adapter are usable in the guest (1003779)
• USB Printer redirection can be confusing if RDP redirection is Enabled. (1003781)
• For USB audio devices shared by the VDM Client to function, audio redirection must be set to “Play in VM (needed for VoIP USB support)” (1003782)
• Blackberry devices should not be shared when in use locally (1003783)
• USB devices sometimes stop functioning and need to be unplugged and reattached to resume operation. (1005565)

Administrative rights requirement for use of VDM USB Driver

USB redirection requires administrative privileges on both client and desktop virtual machines. If the user does not have the necessary privileges in both places, the USB device redirection functionality will be unavailable.

For Windows Vista clients with User Access Control enabled (the default), to run VDM Client with administrative privileges, follow the instructions in Microsoft KB 922708 on how to run a program as an administrator: http://support.microsoft.com/kb/922708

For Windows Vista guests, disable User Account Control so that VDM Agent components run with administrative rights (running the wssm.exe process as an administrator is not sufficient, as Windows Defender will block this process running with administrative rights at startup when UAC is enabled).