Last updated: May 12, 2022.

Provide the optimal experience for your users.

Class Collaborate runs best on networks that allow WebRTC or Chime over the User Datagram Protocol (UDP). Collaborate also requires web sockets, which is a common web technology.

Firewall settings

By default, Collaborate uses the User Datagram Protocol (UDP) to send information. UDP doesn’t wait to establish a connection before sending a packet. It simply sends the packet making it fast and efficient.

For the best experience, configure your firewall and proxy to allow UDP traffic on ports 49152 through 65535 up to our full Internet Protocol (IP) range for the regional Ultra scheduler that you are using. Sessions utilizing Chime for audio and video media traffic will connect on UDP over port 3478.

If opening the full range of ports is not possible, you can configure your firewall and proxy to allow UDP traffic on port 50000. Collaborate supports WebRTC traffic if the firewall and proxy are not configured to allow the UDP traffic, however this will cause unnecessary latency and some minor frustration for your users.

For the list of domain addresses and IPs that need to be allowed, see the networking article on Class Community and Support (available in English only).

Note: If your firewall is not open to the full WebRTC UDP port range recommended, we’ll try the UDP 50000 port. If that fails, traffic can still connect using the Transmission Control Protocol (TCP) on port 3478 or Transport Layer Security (TLS) on port 443. TCP and TLS are slightly slower connection protocols than UDP. For Chime audio and video media traffic TCP 443 will be used if UDP 3478 is blocked.

Proxy settings

Web Sockets

Collaborate uses HTML5 Web Socket traffic to connect to session servers. Users trying to connect from networks that do not allow HTML 5 Web Socket connections won’t be able to launch Collaborate.

Proxy servers need to allow HTML5 Web Socket traffic in order for Collaborate to connect to the session servers through a proxy. Proxy servers may also need to be specifically configured to handle this Web Socket traffic. In this case, please be sure Web Socket traffic from the domain is added to the allowed list. This is done by your System Administrator.

Not sure if Web Socket traffic works on your network? You can test it. To learn more, see the Class Collaborate and Support article on testing Web Socket traffic on your network (available in English only).


Proxy servers must allow WebRTC traffic for the best Collaborate experience. With WebRTC the experience adjusts dynamically according to bandwidth and network constraints. To learn more, see the WebRTC website.