Implement Quality of Service for Microsoft Teams
What is Quality of Service (QoS) and why we need in Teams? Quality of Service is process of classifying the traffic and then prioritizing specific type of network traffic using port ranges, protocol and application. There are different ways to implement Quality of Service. When planning for Microsoft Teams, you must look for to prioritizing Teams specific traffic to optimize user experience. I must admit that the Quality of Services is not an only solution of every call quality problem, however Quality of Service is combination of networking technologies that enables organizations to optimize the end-user experience for real time audio, video and application sharing communications.
QoS is commonly used when network bandwidth is limited and when network congestion, in practice bandwidth limitation and network congestion always there so we must have QoS configure correctly to optimize end-users experience.
QoS is more effective when it configures end-to-end, meaning from user computer where Microsoft Teams client running to network Switches to router to Office 365 cloud means complete end to end signaling and media path. If in case any path doesn’t support QoS could degrade the entire Teams call quality.
As shown in above figure organization network means on-premise network which is completely managed network connected to Interconnect network that is unmanaged network and connected to Office 365 cloud (Teams services) which is again Microsoft managed network.
To implement quality of service, organization can configure QoS on their managed network and Microsoft has QoS on their Office 365 cloud network however to have end-to-end QoS interconnect network (which is unmanaged network) must honor QoS however it is not honoring QoS, to solve this, there is ExpressRoute from Microsoft which can be an option for interconnect network to honor QoS to have end-to-end call quality.
It is recommended to implementing QoS on your organization managed network where your users reside even though you are not using ExpressRoute for interconnect network and there no control on it, because One-to-One audio/video calls will go directly between users computer and not leave your organizations network, provided that there is no firewall between users computer.
Implementing QoS on organization network will increase call quality for One-to-One calls between users. As shown in below figure, media traffic will prefer to go directly and singling via Teams services. So, implementing QoS on your management network will increase call quality for all calls within your network.
How to implement QoS for Microsoft Teams?
There are multiple ways to prioritize traffic however most common way is by using Differentiated Service Code Point (DSCP) marking, DSCP values can applied (marked) based on port ranges and via Group Policy Object. For Microsoft Teams you must use both because Group Policy Object (QoS based) policies are only work for Windows Domain joined machines so, Teams client installed on Windows machine will mark the audio/video/ App Sharing traffic with DSCP values however MacOS, iOS, Android devices will not mark Teams traffic with DSCP values to do so implementing QoS via port-based tagging using network devices will work for non-windows devices, that’s why it is recommended that you use DSCP marking based on port ranges, network devices will identify Teams traffic and mark DSCP values using port ranges means configuring correct port ranges will be key for Quality of Service implementation.
QoS implementation Scenarios:
Scenarios 1.Microsoft Teams deployed or in deploying stage and are planning on implementing QoS via Port Based Tagging. Port Based Tagging is the most reliable method since it works universally throughout all platforms and is the easiest to implement.
Scenarios 2.Microsoft Teams deployed or in deploying stage and are planning to implement QoS via Group Policy Object tagging.
Note: That QoS via Group Policy Object will only work for Domain Joined Windows Clients. Any device that is not a Windows Domain Joined Client will not be enabled for QoS\DSCP Tagging. That’s why Scenario 1 and 2 combined works better for windows and non-windows devices for QoS/DSCP marking.
Scenarios 3.Skype for Business Online deployed including QoS Tagging and are now deploying Teams. Then you don’t have to make any changes because Teams will respect the existing configuration and will use the same port ranges and tagging traffic as the Skype for Business client.
Scenarios 4:Skype for Business On-premise deployment including QoS tagging and now deploying Teams, then you need to modify your existing QoS policies to add Teams.exe with new port ranges for Audio, Video, Application Sharing and File transfer. Refer below table for port ranges and DSCP values for Teams.
Recommended port ranges with DSCP Values and Class: Table
Client traffic type | Port range start | Port range end | DSCP value | DSCP class |
Audio | 50000 | 50019 | 46 | Expedited Forwarding (EF) |
Video | 50020 | 50039 | 34 | Assured Forwarding (AF41) |
Application sharing | 50040 | 50059 | 18 | Class Selector (CS3) |
File transfer | 50040 | 50059 | 18 | Class Selector (CS3) |
I would strongly recommend scenario 1 and 2 together to accommodate Windows computer/devices and non-windows devices including MacOS, iOS, Android etc.
Configure QoS for Teams:
- Configure Port Ranges: Before configuring port ranges, you should check that your network device must be able to classify the Teams traffic, like your Router must distinguish between voice traffic and normal web-browsing traffic. If so, then configure Port ranges to mark traffic on network devices.E.g. your network devices like, Router will identify the Teams based on port ranges and marked Teams unmarked traffic which coming from Windows, MacOS, iOS and Android devices. Like Audio traffic (port 50000-50019 mark with DSCP 46), Video traffic (port 50020 – 50039 marks with DSCP 34) and App Sharing and file transfer port (50040 – 50059 mark with DSCP 18). Once traffic gets marked with respective DSCP values it will get prioritize based on QoS queues or classes. So that, Teams media traffic will get prioritized.Note:you need to work with your network team to prioritize Teams traffic based on port ranges.
- Configure Policy based QoS in Group Policy Object Policies for Teams.
- Login to the Domain Controller or computer which have Group Policy Management installed and open “gpmc.msc”
- Open Group Policy Management Editor > expand Computer Configuration > expand Policies > expand Windows Settings > right click Policy-based QoS > then click ‘Create new policy’. As shown in below figure.
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Figure: Policy based QoS - In Policy-based QoS page > give policy name (e.g. "Teams-Audio") > then Select Specify DSCP Value: "46"> click Next windows configure, Application name as "teams.exe" and port and protocol "UDP and TCP" and port range 50000-50019 for Teams audio traffic.
- Repeat the steps “b” and “c” for Video, application sharing and file transfer with respective port ranges and DSCP values.
- Finally, for testing; make Teams audio / video calls and capture network traffic using Wireshark (https://www.wireshark.org/download.html) or NetMon (https://www.microsoft.com/en-us/download/details.aspx?id=44226) and analyze traffic or open registry and find QoS policy keys.
- Using Registry: On Windows machine > open “regedit” > browse path and validate QoS settings “HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\QoS”
- You can validate QoS tagging using Wireshark:Start Wireshark capture and then make audio/video call between two internal Teams client and capture network traffic to verify, once called stop Wireshark capture. Filter traffic based on UDP protocol and then see the if QoS tagging shows correctly of not. Verify two-way packets and see DSCP value shows correctly.