Classifying Skype for Business with SteelHead QoS


I can still remember episodes of Star Trek whereby video calls were depicted as the technology of the future. The devices were big and clunky, the screens were small, and the dials were prominently displayed on the front panel. What most people couldn’t fathom at the time was that you needn’t have special hardware to create such a scenario—the personal computer was all you needed. As the PC (and Mac) evolved in both memory and CPU, so did the applications to fill the void that we had only dreamed of a generation before. Sure, ISDN had been around for a while but who could afford a minimum of 6 BRI lines required to support basic video, not to mention the essential and expensive video conferencing equipment itself? Then in 2003, along came Skype™, an application that revolutionized telecommunications in ways that had not been seen since the advent of the telephone and television.

Today, Skype has been integrated into Xbox 360 consoles, via collaboration and instant messaging features in MS Office and Outlook, respectively. With a 700-million user base, Microsoft upped the ante and created an extension of their already successful Lync instant messaging tool and rebranded it Skype for Business™. With Skype For Business you get all the features of Skype but with enterprise-grade security and the ability to manage employee accounts. Whereas the non-business version of Skype may not be welcomed in the workplace due to fears wasting bandwidth with personal video calls and file sharing, Skype for Business is now a desired mechanism for increasing productivity amongst workers in disparate geographic regions.

Isn’t all Skype the same?

Ah, if life were only that simple! The table to the left shows you what you’re getting with one and not the other. As you can see, the key features of Skype For Business make it a must-have application for business environments where collaboration over the WAN is paramount. Now, with workers regularly making video conferences, sharing their desktops, and transferring files, the challenge is to have visibility into each of these applications and classify them based on your desired priority. Moreover, Skype for Business is available as an ‘online’ (cloud) service or as a classic on-premises offering via Office 365.

The best part is that it is very easy to get started. For example, if you are a current Lync user accessing the online version via Office 365, all you would need to do is install the new business client (consider it really a free upgrade from Lync) and you’re done. As long as you have another business client to communicate to, you can start taking full advantage of all the new business features this upgrade has to offer. Now, with all your Lync clients upgrading to Skype for Business, how will this impact your bandwidth?

Let QoS pave the way

As done previously with Lync, Riverbed SteelHead can leverage QoS to provide the visibility needed to identify your Skype For Business traffic, classify it, and prioritize on your network. Whether you want to give users high priority but with a certain bandwidth limit for video calls or make file transfers best effort, Riverbed’s QoS can do it, even if you do not need, want, or cannot optimize it. Moreover, QoS rules can be applied to inbound and/or outbound traffic.

How does it work?

Riverbed employs Procera Networks NAVL (Network Application Visibility Library) for DPI (Deep Packet Inspection) which provides real-time, Layer-7 classification of network traffic. In fact, NAVL includes (but is not limited to) the identification of network traffic packet attributes in layers 1-7 using more advanced techniques. This means that Riverbed can identify flows that are encrypted with SSL or use one of the many UDP ports utilized by Skype For Business™ and all this is now possible with SteelHead RiOS 9.5.0.

Sounds great—what does it look like?

Using the reporting menu on the Riverbed’s SteelHead WAN optimization appliance, we can see which QoS class a particular flow is being assigned to, whether it be inbound or outbound traffic. For example, displayed below is a QoS report of a single outbound Skype for Business video call. In addition there is some desktop sharing (identified as “Lync-share, by default), SSL, HTTP, and even classic Skype.  


Since the Riverbed DPI library can identify this traffic, the SteelHeads can do the rest and give traffic the priority you desire without having to worry about configuring ports, VLANs, or assigning DSCP values to tell the appliance what to do. Riverbed’s excellent QoS reporting can also show you the exact traffic rate of your traffic at any moment in time, up to 30 days. If any packets are being dropped to due QoS rules, you can see exactly where and how much is occurring. In addition, you can a custom label for the matched traffic (instead of using the default ones) and take full advantage of Riverbed’s flexible QoS classification by creating a custom multi-level trees structure that fits your business needs. Below is an example of just that where we see such a structure using custom labels to better identify the traffic we are targeting.


QoS on the ground… and in the sky

Whether your Riverbed solution is physical (on-premises) or in the cloud (AWS, Azure, SteelHead SaaS), you can employ SteelHead QoS exactly the same way to expertly classify and shape your Skype For Business traffic.

Further Reading:

Set up Skype for Business Online

Skype for Business Online Service Description

Install the Skype For Business stand-alone client

The Growing Importance of Inbound QoS

Procera’s NAVL Deep Packet Inspection

And learn more about Riverbed SteelHead here.

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