Planning for Video in Lync
Microsoft has recently posted all recorded sessions from the 2014 Lync Conference to the Channel 9 events page on MSDN. Among these are a pair of sessions I presented this year on the topic of planning for and understanding the impact of video traffic on your network.
Video – What in the World are You Doing to My Network?
Networking Track / Level 300 – Technical
“So, you are thinking about adding video to your Lync deployment. Join us for an end-to-end discussion about how Lync utilizes video and what this means for your network. We will discuss bandwidth utilization, planning, and what customers really see on their network after video has been deployed.”
Both sessions cover identical content but due to room capacity some of the breakout sessions required an additional session to meet demand. Recordings of each session can be found at the following locations. The Q&A at the end of each session differs but for the most part the rest of the presentation is the same.
The basic goal for this presentation was two fold. Firstly to further educate people on the technical nuances of video in Lync from how it looks on the client to how it works on the back-end. And secondly to show that although video can be locked down and limited pretty extensively in Lync it is actually not a bad idea to simply leave the defaults and instead just monitor usage retroactively.
The story as it was told walks through technical aspects of the video codecs in play and then looks at how these provide the user experience that was brand new to Lync 2013. This leads into discussion of bit rates and how much bandwidth can be consumed across different video calls and conferencing layouts, and then wraps up with a look at real-world data and feedback.
The important points in this section focus on the use of H.264-SVC (and RTV when older version Lync and OCS clients are involved). A detailed look into the Temporal Scaling behavior of the new SVC codec also describes how a single video stream can provide multiple frame rates without additional costs over the network, up to a point. Additional focus is placed on the different limitations of the various Lync client versions and types available.
Dissecting the Video Experience
This section takes a hard look at how screen real estate, or sometimes the lack of it, has a direct impact on the amount of video bandwidth which can be consuming in a particular call. What you should learn here is that physical screen size places a limit on the bandwidth available for video as does the inclusion of other components like participant rosters, IM conversation windows, and even content sharing (which has its own associated network costs).
Doing the Math
The third section dives into the numbers by reviewing video and audio bit rates across various resolutions and frame rates as well as which of these options are available for different call types. What begins to become apparent at this point is that the more participants in a multiparty conference call with video enabled, approaching up to the maximum of 5 live video feeds, the better in some cases.
The final section reviews actual reporting data provided by Microsoft from their own internal usage of video for the entire 2103 calendar year. Some interesting results and trends appear which all tie back into concepts and behaviors explained earlier in the session. The story wraps up by revisiting why or how the video modality is important and the immeasurable factors out there to keep in mind when planning for video conferencing in Lync.
Additionally this previous article has been updated with links to the posted recordings for all of the other video-related breakout sessions presented by other Lync MVPs, Masters, SMEs, and Microsoft employees.