NDI Bridge – A guide to successfully configuring your port forwarding.

NDI^® greatly simplifies sending high quality, low–latency video across your network. In more complex cases, though, another factor may need your attention.

To extend beyond the local network, applications (such as NDI Bridge) use network communication ports. Connecting to a local application from an external network requires targeting the correct port, and that your network router is set up to accept traffic at that port.

This is much like an office with one main telephone number, but many extensions. On a wide area network (WAN) like the Internet, the ‘public IP number’ corresponds to the main telephone number. Your firm provides a list of extension numbers, each matching one phone. Likewise, your network router exposes certain ports for external access. If the network router doesn’t expose a port, no-one can connect to it.

The NDI Bridge Host finds your public IP address automatically, and listens for traffic arriving at the port you specify in its configuration app. It cannot, however, automatically configure the router to allow traffic from the WAN to reach that port. (By default, routers expose a limited set of common ports, and are manually configured to use other ports for specific purposes.)

Port Forwarding

Exposing a port (or a range of ports) so an external network can communicate with the port used by internal application is called “port forwarding.”

Sidebar: The word “forwarding” highlights the fact that it’s possible (though not required) to expose one port to external networks (the ‘external’ port), and pass traffic between it and a different ‘internal’ port. This is very much like publishing one phone number publicly, then secretly forwarding that number to a hidden, private number.

To configure port forwarding, you just need to know the internal port you will use, and how to access your router settings.

• NDI Bridge defaults to port 5990, but lets you specify a different ‘internal port’ if you wish. (Hint: If you assign a Host port number that is in use, NDI Bridge automatically increments the number until a free port is found. Knowing this, you may opt to forward a port range.)
• Router settings are often available in a webpage published on your local network, though this can vary. Your router documentation will provide details and login information for the router. Alternatively, an Internet search for “port forwarding” locates countless detailed guides (such as https://portforward.com/router.htm). A network administrator may handle this task for you in more complex environments.

Once you have this information, you can access the port forwarding section of your router settings to enter the internal and external port. (Port forwarding options are often found under either “Applications and Gaming” or “Firewall”.) If a Protocol option is provided, select “Both”, or “UDP”.

Hint: The NDI Bridge application automatically tests your port forwarding configuration when you start the Host or modify the designated port. It reports success when everything is properly done.