If you want to know which aspects of Microsoft Lync® are supported in the VDI environment, vague data doesn’t provide the straight facts necessary to make informed decisions.  At the very least, apples-to apples-comparisons are not possible when information is unclear.

So, I am writing to rectify this situation. Allow me to shed some light on the various platforms (Client OS, and versions of Microsoft Lync) that are supported by Citrix XenApp and XenDesktop. This can help you make your own decision when it comes to comparing  what is supported by VMware Horizon 6 to what level of support Citrix provides.

Hopefully, accuracy will make your choice easy.

The Actual Scoop

Citrix supports Windows, Linux and Mac clients. Conversely, VMware only supports a restricted subset of Windows endpoints. VMware does not support Lync running on RDS servers, while Citrix does.

Citrix HDX Realtime Optimization Pack for Microsoft Lync in action!

Microsoft released the Lync 2013 VDI Plug-in (media engine) to provide an optimized architecture for Microsoft Lync 2013. The Microsoft VDI plugin is supported by both Citrix and VMware.  Thus, the support that each provides is equal. Therefore, the VDI plugin is the recommended solution for windows-only deployments.

Supporting Non-Windows End-points (Linux, Mac) in Your Environment

Consider using Citrix’s optimized solution for Lync 2013. Also, if you need Lync 2010 support, the only optimized Lync solution available is the Citrix HDX RealTime Optimization Pack for Microsoft Lync 2010. As a rule of thumb, you should avoid hairpinning (read the footnote at the bottom for more info) and implement optimized transmission of Lync’s audio and video data stream where possible.

Here is a look at the optimized support for Microsoft Lync by the Citrix and VMware virtual platforms:

Note: In the tables used in this post, Citrix XA refers to Citrix XenApp version 6.0 and above, while XD refers to XenDesktop version 7.1 and above. In both cases, there is the HDX Real Time Optimization Pack version 1.5 or above. VMware Horizon denotes Horizon View version 5.2 or later.

Clearly there is a vast difference in the platforms supported.

This is because the support provided by VMware Horizon is limited to the capabilities of the Microsoft Lync VDI Plug-in. On the other hand, Citrix supports both the Microsoft Lync VDI Plug-in and its’ own HDX RealTime Media Engine (RTME) which is compatible with Lync server 2010 and 2013.

To support any of the operating systems with an “x” mark next to them in the VMware column:

  1. You can use the Citrix HDX RealTime Optimization Pack for Microsoft Lync and install the RTME on Linux, Mac and (if desired) even on your Windows devices.
  2. This extends support for optimizing Lync voice and video calling to Linux Thin clients and Mac OS X operating systems, giving the users the flexibility to access Lync from all of these devices.
  3. Additionally the RTME component includes both Microsoft proprietary and industry standard codecs, permitting interoperability with Lync endpoints as well as third-party products that register with the Lync Server such as Cisco, Tandberg and Polycom in-room video conferencing systems.

The Equally Significant Difference

The “Optimization Pack” allows Lync to run as a shared application and as part of a shared desktop on Hosted Shared Desktops.  Not only can you use Windows desktop operating systems to run Lync Server but Windows Server Operating Systems as well. This allows for greater consolidation – resulting in higher user density and increased resource consumption efficiency in the data center.

* Although Windows Server 2012 [R2] is not listed as fully supported by Microsoft at http://technet.microsoft.com/en-us/library/gg412781.aspx, Eason Wang of Microsoft TechNet Community Support comments on this  Lync TechCenter Pageit should be working fine…” and we have verified this in our own testing .

Last but certainly not the least is the fact that with Citrix a number of Lync Server versions can be deployed, giving you the flexibility to install the version that best suits the requirements of your environment.

By the way, Citrix’s support for Lync Online (Office 365 hosted Lync) in the new 1.6 release of the HDX RealTime Optimization Pack for Lync includes AD Federation. So, user accounts can be maintained on-premises in the enterprise without password synchronization to the cloud.

To get a list of all the features that are supported by each of the different methods, Generic, Lync VDI Plugin and the Optimization Pack, refer to the CTX article – http://support.citrix.com/article/CTX200279

The Key Take-Aways?

As the discussion above clearly shows, you need Citrix XenApp and XenDesktop with the HDX Real Time Optimization Pack if any one or more of these situations exist in your VDI environment:

  1. Your users are not going to be using just Windows endpoints to get access to the Microsoft Lync
  2. You want to run Lync on Windows Server operating Systems
  3. You want voice and video streams transmission optimized on Lync 2010 or 2013

Footnote on Hairpinning

Generic Unified Communications (UC) technologies capture media from the terminal and encode and stream it to the client, but this introduces latency, deteriorating audio and video quality, and increases server load, reducing server density. This occurs due to “hairpinning”. Hairpinning is when media is captured in the terminal of the origin and sent to the server (Lync) for encoding, before it is sent back down to the destination client on the terminal for playback. This is especially noticeable in branch offices where you may be calling someone sitting in a building couple of blocks away, but the audio and video lag could feel as though they were half a world away.

The way to avoid hairpinning is to capture and process the media data directly on the terminal without involving the server in the processing. This results in the reduction of bandwidth consumption to and from the server and the lower server CPU utilization as the encoding and decoding now happens on the clients. This is what we call Optimized Delivery (see /blogs/2012/07/18/delivering-softphones-and-uc-apps-with-hdx-real-time-technologies/). Below you can see a graphic of how optimization works:

Note: 5 is where all the Audio and Video traffic is going to be totally bypassing the server, thus reducing bandwidth consumption within the firewall and latency between clients.