Citrix XenDesktop 7.12 and new updates and in-depth on HDX Enlightened Data Transport

So with XenDesktop 7.12 released today I finally got a bit more information on what’s available in the new release. One of the features which was announced was Local Host Cache support is finally back, before I got the time to dig into the material Bas Van Kam did a great blog post on it here –>

You can also see the release notes here on what’s new in 7.12 –>

But one thing did catch my eye, which is the new enlightened data transport layer. Which is a new feature which is now added for evaluation purposes in 7.12

Now this is interesting, since HDX sessions have up until now been based upon TCP (Framehawk is the exception which works great on high packet loss and latency scenarioes) but with alot of customers moving to cloud we are often faced with low packet loss scenarioes but a bit higher latency issues. So customers moving to Azure would often get a suboptimal experence based upon how far away the resources are.

This new enlightened data transport layer is designed for just that! “ Quote:

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”

So how do we enable this evaluation feature? Well there are a couple of prerequsites.

  • XenApp and XenDesktop 7.12 or higher (required to enable the feature using Studio)
  • VDA for Desktop OS 7.12 or higher
  • VDA for Server OS 7.12 or higher
  • StoreFront 3.8
  • Citrix Receiver for Windows 4.6 (download Receiver 4.6 here –>
  • Citrix Receiver for Mac 12.4
  • Add firewall rules to allow inbound traffic on UDP ports 1494 and 2598 of the VDA.
    • Note: TCP ports 1494 and 2598 are also required, however they are opened during the installation of the VDA. In this release, 1494 and 2598 must be manually enabled for UDP.
  • IPv4 VDAs only. IPv6 and mixed IPv6 and IPv4 configurations are not supported.

In Studio, enable the policy setting, HDX Enlightened Data Transport (it is disabled by default).
To enable the policy setting, set the value to Preferred (or Diagnostic mode), then click OK.

  • Preferred. Enlightened Data Transport over UDP is used when possible, with fallback to TCP. No additional configuration is required to optimize for LAN and WAN conditions.
  • Diagnostic mode. Enlightened Data Transport over UDP is forced on. Fall back to TCP is disabled.
  • Off. TCP is used. Setting to Off does not impact other features which use UDP (for example real-time audio transport or Framehawk.And lastly we need to allow the transport method to Citrix Receiver as well, so there we need to configure the group policy setting
    1. Computer Configuration > Administrative Templates > Citrix Receiver > Network Routing > Transport Protocol for Receiver.


    1. Set the policy as needed: Enabled (EDT first with fallback to TCP) or Off (TCP).
    2. Select the Communication Protocol for Citrix Receiver for Windows as Preferred, On or Off.

      So how can we check that its working properly? As by default Citrix uses TCP so if you run a CTXsessions from CMD you will see that TCP is the default shown before we apply the policy, afterwards it should show like this
      UDP –> CGP –> ICA

    3. image

Another approach to see if its working is if course looking more indepth into it using WireShark. ALOT of small packets going back and forth here! so it scales the packet size depending if there is any more bits to be sent across the wire.


My plans to do more in-depth review but I guess it will have to wait a bit before I get some things sorted out. It is of course a completly bummer is that it seems like this feature is not yet supported externally via NetScaler Gateway, which makes is difficult to try out properly in a cloud scenario.

Citrix mentioned that feedback should be posted to this forum –>
UPDATE: ITs now available!

Stay tuned!

0 thoughts on “Citrix XenDesktop 7.12 and new updates and in-depth on HDX Enlightened Data Transport”

  1. Hi Marius

    Thanks for the great insight. The discussion forum for Adaptive Transport a.k.a EDT is now public. Maybe you can edit the post to clarify, so we collect more feedback on performance results in one place. Keep up the great work, buddy!


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