Citrix Enlightened Data Transport or EDT Protocol

By 16 december 2016 No Comments

Citrix Enlightened Data Transport or EDT Protocol

With the release of XenApp/XenDesktop 7.12 there is also a preview of the next generation data transport engine for HDX. This is especially engineered for Cloud Computing. And Citrix have carefully selected techniques that were previously available with Framehawk.

So, I want to describe this at high-level. And look at what components there are and what needs to be configured.

First we have to understand how the current HDX protocol exists.











If we look at the ICA stack today, we can see that is optimized for TCP. And Citrix keeps innovating at this point. For instance “Adaptive Display v2” which was introduced with XenApp/XenDesktop 7.11

In addition to this ICA stack, we have Framehawk and “Real-Time Audio” both of them are optimized for UDP (User Datagram Protocol). This is good for High Packet loss and Latency scenarios for example School Campus or so.

If we look at this text that was published in the Edocs section:


IT administrators can evaluate a new HDX data transport layer designed for challenging long-haul WAN and Internet connections. This alternative to TCP delivers a superior user experience while maintaining high server scalability and efficient use of bandwidth. This new transport layer above UDP improves data throughput for all ICA virtual channels including Thinwire display remoting, file transfer (Client Drive Mapping), printing, multimedia redirection and others. In 7.12, this feature is for evaluation only and is disabled by default. It can be enabled in a non-production environment with a new policy setting

What does this mean.

Enlightened Data Transport is to support TCP and UDP for all virtual channels. So rather having a stack of HDX transport over TCP and UDP. EDT over UDP unifies the traditional ICA stack by adding the enlightened transport to every virtual channel.

This will allow best performance for both interactive sessions like task workers as well as delay sensitive workloads like Skype Calls and video

This technology is also capable of falling back to TCP when needed without any interaction of an administrator.








This automated fallback to TCP can occure if;

  • HDX Client/server connection is running on a network where UDP for instance is blocked.
  • Receiver version of the client is incompatible


EDT is a Citrix protocol that enhances the UDP. So in other words when you run EDT over UDP you will get the best of both worlds. Fast and low bandwidth overhead efficiency and session reliability and end- to end control enhancement because of EDT.

EDT was designed to be better than the current ICA/HDX connections over TCP and UDP. Although it is available in XA/XD 7.12 Citrix advises only to use this in test environments at this point and not in production.

For Framehawk to run you must open a bunch UDP ports. With EDT this is not the case, EDT runs on port 1494 and 2598. These are the same ports Citrix uses for standard TCP.

Requirement for EDT;


  • Citrix Receiver for Windows 4.6
  • Delivery Controller 7.12
  • VDA for Desktop or Server OS 7.12
  • StoreFront 3.8
  • NetScaler Gateway 11.2 (Support data transport over UDP)
  • Ports 1494 & 2598 open.

    To configure EDT you just create a policy from studio.












Preferred: Transporting the data over UDP is used whenever possible, fallback to TCP. This is the default when you want to use EDT

Diagnostic Mode: Transporting the data over UDP is always used, no fallback to TCP

Off: Yes you guessed right, this means TCP is always used.


More on this subject can be found on the following blogs:

Marius Sandbu: