Adaptive transport for XenApp and XenDesktop optimizes data transport by leveraging a new Citrix protocol called Enlightened Data Transport (EDT) in preference to TCP whenever possible. Compared to TCP and UDP, EDT delivers a superior user experience on challenging long-haul WAN and Internet connections, dynamically responding to changing network conditions while maintaining high server scalability and efficient use of bandwidth. EDT is built on top of UDP and improves data throughput for all ICA virtual channels, including Thinwire display remoting, file transfer (Client Drive Mapping), printing, multimedia redirection (though we still recommend to use the ‘Audio over UDP real-time transport’ policy, since EDT is a reliable protocol. Setting that policy will effectively pull Audio out of EDT and allow it to run over a separate UDP port with no reliability). When UDP is not available, adaptive transport automatically reverts to TCP.

 

EDT runs on UDP ports 1494 and 2598.

• CGP (therefore Session Reliability) is optional on direct EDT connections between Receiver and VDA (e.g. corporate MPLS), so the VDA could be listening on UDP 1494 only

• CGP is required for EDT connections via NetScaler Gateway (VDA would be listening on UDP 2598 and 1494 but effectively using 2598)
  This is because of the role Session Reliability plays in the UDP-to-TCP fallback feature, as well as the fact that CGP is used as an authorization protocol via NetScaler (it carries the STA Ticket).

• So if you have a NetScaler Gateway, EDT requires you enable Session Reliability, which in turn enables CGP.

• Session Reliability is enabled in a Studio policy, and Storefront (Manage NetScaler Gateway > Select your NetScaler > Secure Ticket Authority > “Enable Session Reliability”)
  
  

Instructions

1. In Studio, create or edit a policy to enable the setting, HDX Adaptive Transport (it is disabled by default. Note: In XenApp and XenDesktop 7.16, EDT is enabled by default). We also recommend that you do not enable this feature as a universal policy for all objects in the Site.
   1. To enable the policy setting, set the value to Preferred, then click OK.
      1. Preferred – Transporting data over UDP is used when possible, with fallback to TCP.
      2. Diagnostic mode - This value will always transport data over UDP, and fall back to TCP is disabled. We recommend this setting only for troubleshooting.
      3. Off - TCP is always used, and EDT is disabled.

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2. Click Next, and complete the steps in the wizard.
3. The policy takes effect when the user reconnects the ICA session. Though not required, you can run gpupdate /force to pull the policy setting to the server, but the user still has to reconnect the ICA session.

4. Launch a session from a supported Citrix Receiver to establish a connection using Adaptive Transport.
5. For secure external access, configure DTLS encryption on NetScaler Unified Gateway. For more information, see Configuring NetScaler Gateway to support Enlightened Data Transport.
6. Open the right UDP Ports in the DMZ Firewalls:                                                                                    

Note: If using the Command Line install for the VDA, then the UDP Ports need to be explicitly opened.

XenDesktopVDASetup.exe /ENABLE_HDX_UDP_PORTS

Not to be confused with pre-existing command line:  
/ENABLE_HDX_PORT which only opens Audio/RTP ports
 

• EDT How do I: https://support.citrix.com/pages/xaxd-how#EDT
• CTX220730 - How to Confirm HDX Enlightened Data Transport Protocol is Active
• CTX230014 - How to Troubleshoot EDT Connections
• CTX226385 - Troubleshooting DTLS and EDT on the Netscaler Gateway
• CTX230011 - EDT Session Connection/Reconnection Attempts using UDP and TCP in Parallel
• CTX230010 - Windows OS VDA 7.16 Schannel library support for DTLS
• CTX230012 - EDT Security using DTLS
• CTX231821 - How to Configure EDT when using VPN solutions
• CTX226014 - Application Launch Fails with "Unknown client error 1110" When Using EDT/DTLS on NetScaler Gateway
• CTX224373 - XenDesktop 7.x Unable to launch published desktop with Adaptive transport policy enabled