Dec 2014

Can you really deploy Lync on Citrix XenApp and XenDesktop?

I’m constantly asked by customers if you can deploy Lync Voice and Video on a Citrix XenApp or XenDesktop platform and deliver a reasonable experience to end users. My answer is YES but there are caveats you need to be aware of.

Essentially there are four deployment options you need to consider carefully before you start testing as each of them will deliver a different Lync experience to your end users. Your selection should also consider any Microsoft and Citrix Support agreements you have in place as certain architectures may not be supported by either vendor.

So what are the four options?

  1. Generic HDX RealTime
  2. Microsoft Lync VDI Plug-in
  3. HDX RealTime Optimisation Pack
  4. Local App Access or Reverse Seamless

Option 1: Generic HDX RealTime

There’s always a do nothing option and this is essentially out-of-the-box functionality where all the processing is generated and executed on the server-side rather than the client. Citrix has invested a significant amount in their HDX protocol and with each new release of XenApp and XenDesktop video and multi-media capabilities seem to get better and better.

While I like this option, it will consume a large amount of resources on your Citrix backend infrastructure. Thorough testing and capacity planning is essential, particularly if you plan to deliver a large amount of video content to your end users.

To save yourself a bit of time, I suggest you read this Dell whitepaper. The authors have essentially done a lot of the hard work for you in regard to capacity planning. This should give you an appreciation of what to expect on your backend and if it’s commercially viable in your environment to deliver ‘native’ Lync.

While there are infrastructure considerations with this option, there are no client side components to configure, a massive advantage from administrative point of view.

Option 2: Microsoft Lync VDI Plug-in

With this option, the Lync VDI-Plug-in runs locally on the Thin Client or Fat-Client device and pairs with the Lync 2013 Client residing on the Citrix backend.

The VDI Plug-in is essentially the Lync media engine packaged on its own so the user interface and business logic runs on the XenApp/XenDesktop server but the audio/video processing workload is shifted to the user’s Windows device.

While this approach has a positive impact on delivering video content, it does mean the client side device requires appropriate resources. This option also requires the end point to be a Windows Operating System. It’s not supported with Lync On-Line through Office 365.

In considering this option, you should also factor in that not all Lync functions work with the VDI Plug-in. They include:

  • Integrated Audio Device and Video Device tuning pages
  • Multiple-view video
  • Recording of conversations
  • Joining meetings anonymously (that is, joining Lync meetings hosted by an organization that does not federate with your organization)
  • Using the Lync VDI plug-in along with a Lync Phone Edition device
  • Call continuity in the case of a network outage
  • Customized ringtones and music-on-hold features

It also doesn’t work for XenApp Seamless applications on Windows Server 2012 R2 and is currently only supported with Windows Server 2008 R2.

Option 3: HDX Real-time Optimisation Pack

Citrix HDX RealTime Optimization Pack for Microsoft Lync 2010 is another option to optimise the Lync experience but it only works with Microsoft Lync 2010. I understand a Lync 2013 release from Citrix is imminent.

This solution disables native Lync Audio and Video on the server side and redirects that content to the client end point. It requires software to be deployed on both the server and client side. The client component is called Citrix HDX RealTime Media Engine. It integrates with Citrix Receiver while the server side component, Citrix HDX RealTime Connector for Lync, runs alongside the Lync client on either the XenApp or XenDesktop instance.

This solution was developed and tested by Citrix, not Microsoft, so you should confirm your support entitlement from Microsoft before you consider deploying this option.

One major advantage is HDX RealTime Media Engine has broader support from a client side perspective than the VDI Plug-in and it includes:

  • Macintosh OS X
  • Microsoft Windows and Windows Embedded
  • Linux

Similar to the VDI Plug-in there are a number of limitations in regard to Lync functionality that you need to take into account.

Option 4: Reverse Seamless

In the latest version of XenApp and XenDesktop (7.6), a new feature has been added called Local Application Access or Reverse Seamless. This essentially provides an option where you can deliver applications to an end-point locally that aren’t an ideal candidate to virtualise and then integrate that application into the whole Virtual Desktop experience.

One caveat is that application sharing is not possible since the Lync client isn’t running on the same machine as the user’s other apps (they’re running on the XenApp/XenDesktop server). Screen sharing, however, works fine.


Hopefully this high level view of each option has been of interest, and has provided useful details of certain things to watch out for during testing.

Essentially there is no silver bullet here and no one size fits all model.  Each option brings with it complexities and nuances.

For that very reason, I would recommend starting with Option 1: Generic HDX RealTime (given there’s nothing to install on either the client or server) and see if it makes sense for your environment. Previous experience has shown this option supports a larger number of scenarios and provides a more simple deployment process.

You should also remember there’s no reason why you can’t combine and deploy multiple options based on use case and provide complete flexibility to your end users.

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