What speed fusion settings do you use -Low latency for radio broadcasting

I work as a service tech at Swedish Radio. We develop our second OB-backpack as I write this post and is curious about how you tweak your settings connected to the speed fusion technologies, especially the wan smoothing.

The transit max duo is one of the cornerstones in the new backpack and a new acquaintance for all in our team, so trying to learn as much as we can:) We don’t send a lot of data(opus,) but are picky about the latency and robustness.
So, reaching out for tips and tricks, and tweaks.

I also got a couple of questions:

Don’t fully understand the Maximum level on the same link setting. If set to normal, will it send the redundant packet on the same link as the original packet?

The overall redundancy level, for example, the high setting. If I got three active wan connections will it send more packets per original packet spread over the wan links compared to the medium setting?

Hi Patrik.

Yes it will. This will happen in one of two cases, when there is only a single active WAN, and when you have set the WAN smoothing level to a value where the number of redundant packets generated have to be sent duplicated on the same link because there are not enough tunnels.

WAN Smoothing - Off

  • A packet will be carried using 1 tunnel.

WAN Smoothing - Normal

  • We will duplicate another packet. Hence, 2 packets will be carried using 2 different tunnels.

WAN Smoothing - Medium

  • We will duplicate another 2 packets. Hence, 3 packets will be carried using 3 different tunnels.

WAN Smoothing - High

  • We will duplicate another 3 packets. Hence, 4 packets will be carried using 4 different tunnels.

WAN Smoothing - Maximum

  • We will duplicate packets based on available tunnels. By referring to the attached drawing, 9 packets will be carried using 9 different tunnels.

What is your suggestion in our case for optimal transmition of low latencey audio data.

We use a max transit duo with 2+1 wans. The third one is a small teltonika lte-router. So, three mobile connections.

For the moment i have one pepVPN tunnel and the wan smoothing on Maximum

Whats at the other end / hub in the form of connectivity? If only a single WAN you might as well have WAN smoothing set to Medium. I would also turn on FEC so you have error correction and packet duplication. Then measure the latency difference with FEC enabled and disabled to see if its acceptable.



Ok, thanks Martin!

Yes, one wan connection at the hub end.