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How to optimize Skype for Business user experience over Wi-Fi Network?

How to optimize Skype for Business user experience over Wi-Fi Network?


We are talking about wireless world, from Computer / workstation to Mobile first world. Our connectivity priority also changed from tradition wired connection to wireless (Wi-Fi) connectivity.

Microsoft Skype for Business (Lync) officially supported over Wi-Fi network for optimal experience. However, your existing Wi-Fi network may not provide optimal experience to your Skype for Business user. Because may be initially your Wi-Fi network was designed for DATA traffic and If we are trying to use same Wi-Fi network for Real-Time Media traffic which is generated by Skype for Business client in terms of Audio/Video calls, Conference, IM, application Sharing etc. So we have to redesign/deploy or re-configure your existing Wi-Fi network to support Real-Time Media traffic.

Let’s discuss about devices which are actually using Wi-Fi network. Separate these devices in to two categories, Managed and Unmanaged devices.

Manage devices: Laptop, desktop, Surface, Mobile Phone (iOS and Android) etc. are having some kind controls.

Unmanaged devices (Bring Your Own Device): above all devices counts under this category however without control.

When, I say managed devices which we can control, there we can do something like tagging all Real-Time Media Traffic using GPO, QoS (Quality of Service), WMM (Wi-Fi Multi-Media) etc. however what about unmanaged devices?

There we have no control on BYOD devices. There is no by default tagging on Wireless, no QoS/WMM.

But same time we should provide better quality to these users who brings BYOD devices. To control on these devices and provide optimal experience to users who are waking in campus while connected to conference call and switching from one AP (Access Point) to another APs. User expect same call quality when they connected from any devices with any networks. 

Why my Wi-Fi working for fine with other application but not with Skype for Business (Lync)?

Basically, there is fundamental difference in term of traffic generated by other application and Skype for Business (Lync).

  • Other application does streaming and play vs Skype for Business needs Real-Time Media traffic, no streaming.
  • Video playback applications like YouTube, Netflix, etc. can utilize large receive side buffers in order level out network delays.
  • Real-Time media is interactive and requires a high-performance network that can sustain continuous up/down stream traffic, with low-latency, low jitter with no packet loss.
  • Our goal is to maintain Round trip time delay 100-200ms, Jitter <10 2="" and="" between="" client.="" loss="" ms="" packet="" span="" under="">

Enough talking, lets discuss what we can to enhance users experience.

Note: below images and configuration path using Aruba AP/Controller.

Best practices for Wi-Fi infrastructure:

      • Use enterprise Wi-Fi controller with thin enterprise grade Access Points or standalone APs. Use enterprise grayed APs with provider support and SLA. There are many Wireless provider who already approved by Microsoft. Like Juniper, Aruba, Cisco, Meru, Extreme Network, HP, Motorola, Ruckus and Dell etc.
      • Wi-Fi works better with SDN API Interface: Skype for Business SDN Interface allows developers to build applications and services that can monitor, isolate and correct issues on the network that affect Skype for Business quality of experience. Refer my article (Skype for Business SDN API Configuration Guide).
      • How does SDN Interface work? and helps to improve quality?
        • Skype for Business SDN (API) Interface can be installed on a Skype for Business /Lync Server 2013 (Dialog Listener) and SDN Manger on separate server. Skype for Business SDN API provides an interface through which the Wireless controller can access Skype for Business network diagnostic information for media traffic i.e. voice and video calls, desktop sharing, and file transfer. The Wireless controller uses this data to prioritize Skype for Business traffic and provide information on the usage of Skype for Business applications on the network. The Skype for Business server communicates with the controller through XML messages over HTTP or HTTPS.
      • Design for capacity based on number of clients in coverage area. For regular office space, conference rooms, common areas, do your math and place AP accordingly, including hallways and passage. Place more AP around big conference rooms to support extra load.
      • Plan for overlapping AP coverage for redundancy is required. Keep in mind, high ceilings and long corridor spaces can cause Wi-Fi signals to spread resulting in poor WLAN efficiency. Remediate high ceiling using mount.
      • Sufficient AP density for seamless coverage. Deploy applicable AP density for required coverage and capacity but keep signal level (RSSI -Received Signal Strength Indicator) between -45dBm to -65dBM and SNR (Signal-to-Noise Ratio) better then 30dB (40db preferred).
      • Deploy 802.11n/ac standard APs. 802.11ac is better for good quality because 802.11ac is a high speed and performance next-generation Wi-Fi that is rolled out in a wide variety of client devices.
        802.11ac is ideal for the high bandwidth requirements of clients running unified communications. In our case Skype for Business (Lync).
      • Implement QoS (Quality of Service) /WMM (Wireless Multi-Media) Configure QoS settings (DSCP (Differentiated Services Code Point) -WMM mapping on the SSID profile) to match QoS settings on the wired network and any upstream QoS settings on the client. This ensures that the same DSCP values are used throughout the wireless and wired network for Skype for Business voice/video traffic. E.g. If you set DSCP value for Audio 46 and Video 34 on wired network, then use the same values for DSCP mapping for WMM.
        Refer below Image:
      • If you have not implement QoS, then you must have enable QoS on Skype for Business Servers and clients, use below command to enable QoS on Server.  Set-CsMediaConfiguration -EnableQoS $True
        Also, ensure that the same QoS tagging is configured and validated across all wired network switches, router, WAN circuit and AP and Wireless controller to maintain end-to-end Quality of service.
      • Impalement WPA2 encryption which is in Enterprise Mode.
      • Deploy APs featuring dual (concurrent) 2.4 GHz and 5 GHz operation with 3x3 configuration and 1 Gbps backhaul. Now days Access Point comes with 3x3 configuration.  
      • Support for RF (Radio Frequency) auto radio management of channel and signal strength. Auto management for power management, channel allocation this system should deal with itself when you configured with Auto Radio Management.
      • Fast BBS transition support for 802.11r Standard. This is for mobility and key caching. Most of above Wireless provider support for 802.11r standard. Fast BSS Transition mechanism minimizes the delay when a voice client transitions from one BSS to another within the same ESS. Fast BSS Transition establishes security and QoS states at the target AP before or during a re-association. This minimizes the time required to resume data connectivity when a BSS transition happens.
      • Enable AP load balancing. This again very important because if you have big room where most of users trying connect to steer user in to different APs. Client connection balanced by Controller.
      • Try to minimize 2.4 GHz band:
        • Try to drop 11b support.
        • Limit 11n support to 20 MHz channels.
      • Use 5 GHz band:
        • Enable band steering of dual band capable devices to 5 Ghz
        • 40 MHz channel.
      • You make sure the marking is there for all domain join machines/devices/Servers put GPO to mark the Skype for Business traffic with port ranges and DSCP values. QoS is combination of network technologies, your network device should trust traffic and honor DSCP vales. You can refer my  Deploy QoS for SfB.
        For Android and iOS devices will get tagged via wireless controllers. Remember, I suggested to use enterprise Wi-Fi controller.
      • Ensure proper QoS on wired network, refer how to Deploy QoS for SfB. Configure QoS trust on all voice ports to honor the QoS markings.
      • Ability to classify and prioritize Lync traffic (SIP-TLS) in the presence of lower priority data traffic.
      • Enable power saving mechanisms.

Best practices for client who use Wi-Fi Network:

Client is also infrastructure tool which is more vulnerable and potentially contribute to poor quality. So, we must reconfigure/ reinstall client software to optimize user experience.

      • You must use enterprise class notebooks in order to achieve call quality.
      • High-quality dual band NIC with at least 2x2:2 configuration. E.g. Dell, HP, Microsoft etc.
      • Support for Radio resource management 802.11k.
      • Real Time Media optimized/certified wireless NIC and drivers. If you see poor call quality, then first thing you do is to verify headset and update your wireless NIC drivers.
      • Manage NIC driver versions
      • Mobile devices supporting dual band is better for call quality.
      • BYOD devices is a reality so be prepared for un-managed devices.
      • Use Microsoft certified headset, sometime Bluetooth headset also contribute to poor quality.

Validate your Network and Testing:

Testing and validation is another important step. Without testing and validation how you know, your wireless controller is correcting un tagged traffic. So, test properly.

Testing scenarios:

      • Make Audio Video call Skype for Business app iOS device to another iOS or Skype for Business app on Android device user and check DSCP value correction is there. Like below image.
      • Make call from Skype for Business app iOS user to Skype for Business Windows user and validate DSCP tagging’s.
      • Check network statistic and utilization.
      • Check Skype for Business call quality results per location wise, by traffic class (voice, video, application sharing)

Auditing configuration:

Your job is not after setting up your Wireless network, QoS, traffic prioritization etc.

      • You must monitor and visit your network devices frequently.
      • Audit network device, wireless controller and QoS configuration quarterly to minimize human errors.


Thank you.


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