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Use RDP Multipath to improve connection reliability to Azure Virtual Desktop

Important

RDP Multipath is now Generally Available (GA). We are actively rolling out this feature to production in phases, with an increasing percentage of connections benefiting from RDP Multipath as deployment progresses. During this period, not all connections use RDP Multipath immediately. Our commitment to quality guides each phase, ensuring a stable and reliable experience for all users as progress toward full availability.

Remote Desktop Protocol (RDP) Multipath improves session stability by continuously monitoring multiple networks paths and dynamically selecting the most reliable one. This intelligent switching mechanism helps reduce the likelihood of disconnections and contributes to a smoother and more consistent user experience.

It offers several key benefits:

  • Seamless integration: No configuration changes are needed beyond ensuring your environment supports RDP Shortpath.

  • Intelligent path management: ICE discovers and evaluates multiple Remote Desktop Protocol (RDP) Shortpath routes using User Datagram Protocol (UDP) over STUN (Simple Traversal Underneath NAT) and TURN (Traversal Using Relays around NAT) protocols.

  • Enhanced reliability: Backup paths remain on standby. If the active path becomes unstable or fails, RDP Multipath automatically switches to the next best path, reducing session drops and interruptions.

RDP Multipath uses multiple network paths, discovered with Interactive Connectivity Establishment (ICE), to improve connection reliability. These paths can include combinations like UDP over STUN or UDP over Relay. If the main connection fails, the system automatically switches to a backup path. If all paths are lost—such as during a network outage—the system tries to reconnect once the network is available again. 

Note

This version of Multipath does not support users who connect exclusively through WebSocket (TCP-based).

The following diagram illustrates how RDP Multipath works with Azure Virtual Desktop. In this user scenario, the primary active path is the connection of UDP via STUN, supplemented by two redundant UDP connections through a TURN server:

A diagram showing RDP Multipath connections over RDP Shortpath using STUN and TURN.

Prerequisites

RDP Multipath works automatically when the following prerequisites are met:

Verify RDP Multipath connectivity

There are two ways to verify that RDP Multipath is being used for a connection:

  • Users can check the connection status of a remote session from the connection bar, which shows RDP Multipath is enabled, as shown in the following example screenshot:

    A screenshot of connection information showing that RDP Multipath is enabled.

  • Azure Virtual Desktop administrators can view connection reliability information in Azure Virtual Desktop Insights. For more information, see the connection reliability use case for Azure Virtual Desktop Insights.

    If you find some connections aren't using RDP Multipath, check that a firewall or other network restrictions doesn't block RDP Shortpath connections. A connection using STUN or TURN protocols is required.

Manage RDP Multipath Availability

RDP Multipath is being rolled out in phases. If you’d like to manually control the feature availability on your session hosts, you can use the following registry key to either opt in or opt out.

To enable RDP Multipath early (opt in):

To enable RDP Multipath ahead of the full rollout, set the following registry key value to 100:

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\RdpCloudStackSettings" /v SmilesV3ActivationThreshold /t REG_DWORD /d 100 /f

To disable RDP Multipath early (opt out):

If you prefer to disable RDP Multipath until the rollout is complete, set the registry key value to 0:

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\RdpCloudStackSettings" /v SmilesV3ActivationThreshold /t REG_DWORD /d 0 /f

Note

After updating the registry key, users must disconnect and reconnect to the session host for the change to take effect.

To learn more about RDP Shortpath, see RDP Shortpath for Azure Virtual Desktop.