Citrix initially introduced Enlightened Data Transport (EDT) — our UDP-based reliable transport protocol — to help enhance the performance of ICA sessions in higher latency networks as the distance between users and their resources started to grow due to global data center consolidation efforts and the inevitable migration of workloads to the cloud.

Now, we’ve added a feature that makes EDT even smarter and more robust. I’m excited to finally announce that EDT has MTU Discovery capabilities!

MTU Discovery enables EDT to automatically determine and set the appropriate MTU for each session, so every session will use the MTU that is best for that user’s connection, avoiding packet fragmentation and providing enhanced performance and reliability. Given the recent increase of remote work in the current climate, this feature could not have come at a better time!

As workshifting and worker mobility within the workplace became more common, users started to connect to their published resources via a variety of different networks that were not as prevalent before. We started seeing more users connecting to their corporate networks via Wi-Fi instead of a hardwire. They were connecting remotely from home leveraging a multitude of ISPs, from coffee shops using many different Wi-Fi solutions, and from many other places using mobile hotspots from various providers as well as different networks (3G, 4G, LTE, etc.). In other words, networks became unpredictable. And today, this is more relevant than ever.

We had great results and successes with EDT, but as network characteristics started to change, we began to receive reports of issues that ranged from mild perceived performance problems to inability to connect to sessions. Once our development teams started researching this, it became clear that packet fragmentation was to blame.

To address this in the short term, we came up with a workaround that allows the configuration of a custom MTU for EDT, details of which you can find in CTX231821. This, however, was always meant to be a temporary workaround. We strive to continuously improve our stack and simplify the deployment and configuration of our solution.

But enough about how we got here.

To help you get started today, here is what you need to use the feature:

  • VDA version 1912 or newer
  • On the client, Citrix Workspace app for Windows 1912 or later
  • Session Reliability must be enabled
  • If using Citrix Gateway, ADC 13.0.52.24 or newer OR ADC 12.1.56.22 or newer
  • The feature is disabled by default. Details on how to enable it are available in the documentation.

As you may have noticed, I only listed Workspace app for Windows. At the moment, Windows is the only platform that supports EDT MTU Discovery. Support on other platforms (i.e., Linux and Mac) will come in the future, though.

In the meantime, I recommend you enable MTU Discovery and configure a custom MTU (if needed). That way, clients that support MTU Discovery will be able to use it, and those that don’t will be able to use the custom value instead.

If you have any questions or comments, please drop them in the comments below.

For Citrix Investors

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