Teams, Zoom and Webex issue

[gmukesh]

Symptoms: Video freezing and Voice interruption issues on Teams, Zoom and Webex.

Diagnosis: The protocol which is used for Voice and Videos is UDP. But on other hand, the protocol which is used for Chat is TCP. There are some specific UDP ports which need to be allowed in network for best experience of Voice and Video.

How issue start?: Issue starts when Voice and Video traffic start going via TCP (port 443).

TCP is connection oriented and UDP is connection less. Via using TCP port 443, if client would not get any response/ acknowledgement of any transmitted packet, it will re-transmit the same packet again. So lets assume, during Webex call (when it uses TCP), if client would not get any response of a TCP packet, it will re-transmit again until it get any response. This re-transmission can cause delay/ lag of voice traffic.

UDP performance is fastest at delivering packets on the network for many reasons. The first is that it doesn’t check if the packet is fully received. Another is that this protocol is not sensitive to packet reorder. This means that UDP can deal with it without considering it as packet loss.

Solution:

For any kind of Teams, Webex and Zoom interruption issue, we have to make sure that below UDP ports should be open from firewall or from switch (see if extended ACL is blocking the ports or not):
Teams:
3478
3479
3480
3481

Webex:
9000
5004

Zoom:
8801
8802

Please refer below document related to Teams, Zoom and Webex:

Teams: https://learn.microsoft.com/en-us/answers/questions/896023/when-does-microsoft-teams-use-tcp.html

Zoom: https://www.speedguide.net/port.php?port=8801

Webex: https://help.webex.com/en-us/article/WBX264/How-Do-I-Allow-Webex-Meetings-Traffic-on-My-Network?#id_135400

I have attached a case study.

Thanks.

[JPavonM]

@gmukesh let me add some Zoom resources to enable independent ports, and take advantage of that to create QoS profiles for audio/video/chat streams (in Windows):

Zoom | Set QoS DSCP Marking Procedure

[gmukesh]

@JPavonM thank you so much for adding this great document. It will really help us.

Thanks

Gourav