Announcing public preview of RDP Shortpath transport for Windows Virtual Desktop

As we promised during the Microsoft Ignite conference, we are introducing a new capability that can take into account the type of network you are connecting from, and when possible, establish a direct peer-to-peer UDP transport rather than using the Windows Virtual Desktop gateways.

For a starter, I would like to remind you that Windows Virtual Desktop uses Remote Desktop Protocol (RDP) to provide remote display and input capabilities over network connections. RDP has initially released 22 years ago with Windows NT 4.0 Terminal Server Edition and was continuously evolving with every Microsoft Windows and Windows Server release. From the beginning, RDP developed to be independent of its underlying transport stack, and today it supports multiple types of transport. It could be a Hyper-V bus transport for managing VMs using the Enhanced Session Mode or TCP-based transport in Quick Assist, or combined TCP/UDP transport for on-premises deployments.

When we designed Windows Virtual Desktop, we built an entirely new transport called Reverse Connect. Reverse connect transport is used both for establishing the remote session and for carrying RDP traffic. Unlike the on-premises RDS deployments, reverse connect transport doesn't use an inbound TCP listener to receive incoming RDP connections. Instead, it is using outbound connectivity to the Windows Virtual Desktop infrastructure over the HTTPS connection. This gives a secure and simple way to implement connectivity for your remote desktops. For the details about reverse connect, see a brand new topic in Windows Virtual Desktop documentation.

While reverse connect gives a secure and reliable way of communicating with desktop, it is based on TCP protocol, and its performance is heavily dependent on the network latency. It also inherits other drawbacks from TCP, such as slow start, congestion control, and others.

Introducing RDP Shortpath

RDP Shortpath is a family of UDP-based transports that extend Windows Virtual Desktop connectivity options.

Key benefits of Shortpath are:

• RDP Shortpath transport is based on top of a highly efficient Universal Rate Control Protocol (URCP). URCP enhances UDP with active monitoring of the network conditions and provides fair and full link utilization. URCP operates at low delay and loss levels as needed by Remote Desktop. URCP achieves the best performance by dynamically learning network parameters and providing protocol with a rate control mechanism.
• RDP Shortpath establishes the direct connectivity between Remote Desktop client and Session Host. Direct connectivity reduces the dependency on the Windows Virtual Desktop gateways, improves the connection's reliability, and increases the bandwidth available for each user session.
• The removal of additional relay reduces the round-trip time, which improves user experience with latency-sensitive applications and input methods.
• RDP Shortpath brings support for configuring Quality of Service (QoS) priority for RDP connections through a Differentiated Services Code Point (DSCP) marks
• RDP Shortpath transport allows limiting outbound network traffic by specifying a throttle rate for each session.

Sounds good? Then try it yourself by following the detailed documentation.

Feedback

We'd like to hear from you about your experiences with this public preview!

• For questions, requests, comments, and other feedback about RDP Shortpath, please use this feedback form.
• Don't hesitate to post feature suggestions on: https://aka.ms/wvdfbk

Next steps

Learn more in the brand-new networking section of Windows Virtual Desktop documentation :

Understanding Windows Virtual Desktop network connectivity

Windows Virtual Desktop RDP Shortpath

Implement Quality of Service (QoS) for Windows Virtual Desktop

Remote Desktop Protocol bandwidth requirements