Last Updated on January 28, 2022
Recently, I was reviewing Citrix HDX RealTime Optimization Pack deployment for Skype for Business for one customer. I noticed that on many VDIs, it was reporting as HDX RealTime Connector – Unoptimized. It turned out that all those VDIs were accessed by un-managed Endpoints where users had upgraded their Citrix Receiver to Citrix Workspace App.
Citrix HDX RealTime Optimization Pack provides a real time, crisp high-definition audio-video conferencing and Voice over Internet Protocol enterprise telephony through Microsoft Skype for Business. The Optimization Pack uses existing Microsoft Skype for Business infrastructure and inter-operates with other Microsoft Skype for Business endpoints running natively on devices – Source.
Upgrading to a latest version of Workspace App looks like a fair thing to do but when you upgrade to Workspace App, the RTME (Real Time Media Engine) component of HDX Optimization Pack also gets updated. For HDX Optimization for Skype for Business to offload audio and video call processing to endpoint device, both RTME and RTC (Real Time Connector) should be of same version. RTME can never be on higher version than RTC. RTC component of HDX Optimization pack works on VDI or RDSH server whereas RTME is a receiver plug-in that is supposed to works on the client side.
As of this writing, the latest version of HDX RealTime Media Engine (RTME) is 2.9.400 as part of Citrix HDX RealTime Optimization Pack (RTOP) 2.9 LTSR CU4 (supported until October 14, 2025). RTOP 2.9 LTSR CU4 supports the following minimum versions to the latest versions of Citrix Workspace app:
- Citrix Workspace app 2006.1 for Windows
- Citrix Workspace app 2005 for Mac
- Citrix Workspace app 2006 for Linux
RTME plug-in can be installed and downloaded separately from here.
If RTME is higher than RTC then all audio and video call processing will fallback to VDI or RDSH server. This is when users will start seeing a small pop up in the system tray with a message Citrix HDX RealTime Connector – Unoptimized.
In my case, RTOP 2.3 was installed on VDI images, which means RTC is 2.3, but users had Workspace App 1912 LTSR CU1 for windows and Workspace App 2101 for Mac installed on their devices, which means RTME (2.9) is higher than RTC. That’s the reason users were getting “Citrix HDX RealTime Connector – Unoptimized”.
Citrix Workspace App 1912 LTSR Baseline Components
|XenApp and XenDesktop 7.6 LTSR with or without CUs, up to and including CU8
|XenApp and XenDesktop 7.15 LTSR with or without CUs, up to and including CU5
|Citrix Virtual Apps and Desktops 7
|Citrix Virtual Apps and Desktops 7
|Current Release 1912
Click on that pop up and it should open up a window. If it doesn’t, right click on Citrix HDX RealTime Connector and select open. Notice that both RTC and RTME are local to the VDI.
RTOP 2.3 only supports following versions of Citrix Receiver.
- Receiver for Windows 4.x
- Receiver for Mac 12.x
- Receiver for Linux 13.x
So, I had two options – upgrade RTC to 2.9 CU4 or downgrade Citrix Workspace to Citrix Receiver 4.12. I ended up doing the later because RTC 2.9 doesn’t support windows 7 (the OS of my VDI estate).
Once that was done, I relaunched the VDI. Citrix HDX RealTime Connector – Unoptimized changed to Citrix HDX RealTime Connector – Connected. Notice that RTME is not local to the VDI anymore. It is running on the endpoint device, which is Windows 10 home in this case.
During this exercise, I used Citrix Monitor (Citrix Cloud version of Director) to pull users’ session details. Extracted data for Users’ sessions has a column called Receiver Version, which shows the build version like 14.9.6000.6, 220.127.116.11 or 18.104.22.16830. You can get an idea that 22.214.171.12430 is Citrix Workspace App 2112.1 for windows, 126.96.36.199 is Citrix Workspace App 1912 for Mac and so on. But I wanted the release version rather than build version of Workspace App/Receiver to make the data more presentable in Bar charts. So, I decided to prepare a list of all Workspace App and Receiver Citrix has released so far for all platforms (Windows, Mac, Linus, iOS, Android, Chrome OS and HTML5). That list is available at List of Citrix Workspace App and Receiver.
- Install the RealTime Optimization Pack | HDX RealTime Optimization Pack 2.9 LTSR.
- HDX RealTime Media Engine for Microsoft Skype® for Business – Citrix.
- HDX RealTime Optimization Pack | Legacy Documentation (citrix.com)
- Lifecycle Information for HDX RealTime Optimization Pack (citrix.com)
- Download | HDX RealTime Optimization Pack 2.9 LTSR (citrix.com)
- Troubleshoot the RealTime Optimization Pack | HDX RealTime Optimization Pack 2.9 LTSR.