Speedfusion VPN bondin in high latency WAN links


We were trying to use KA Band satellite VSAT link together with LTE links without success.

Using 2 LTE connections with the same priority (1) and about the same latency for video stream upload using UDP/RTP load balancing was working.
When latency of one of WAN connection was higher (like satellite connection 900 ms), load balancing was not working, only lower latency connection was used.

Is there any way to get different networks with different latency to work together (like LTE + VSAT)?
Peplink recommendation is to use lower latency links for important traffic, in our case it is opposite.

Our application is to use bonding for live video transmission (up to 15 Mbps) with UDP/RTP protocol using cellular, ADSL and satellite VSAT networks together. The highest latency KA Band satellite connections should have highest priority because it is the most reliable (up to 10 Mbps uplink per terminal).


Hi, Some questions. You mention both load balancing in the text and VPN bonding in the title of your post. Which are you trying to achieve? How many separate live video transmission are you working with (how much bandwidth per stream)? What’s the application? I assume if you are using vSAT that our device is stationary for the duration of the video transmission?

You can consider the use of asynchronous SpeedFusion VPN (where in your case, VPN traffic is downloaded over cellular and uploaded over vSAT ) to reduce the apparent latency of the vsat link. I have written a little about that here: http://www.martinlangmaid.com/blog/reduce-vpn-latency-satellite-links/


Hi Martin,
We try to put for instance 12 Mbps RTP uplink stream to VSAT (8 Mbps) + LTE (4 Mbps) with Max HD2 and receive it with Balance 380 connected to fiber.
To do this we would like to use SpeedFusion VPN and split the stream with it to different WANs.
The problem is that VSAT has latency of 800-900 ms and LTE about 100 ms.
Asynchronous SpeedFusion VPN may work, but opposite than you proposed in the document you mentioned.
Best regards Leif


Hi Leif,
A 12Mbps RTP stream is pretty big. Is that a single HD video stream? If so, what’s the resolution/framerate of that? Is it perhaps a combined video stream (4 or 6 individual streams within the 12Mbps)? If so I wonder if we could split those streams out and spread them across multiple VPN tunnels… are you only using VPN for bonding? Is the stream target (receiver) publicly available on the internet?

As you note, VPN bonding across links which such a wide latency range is very difficult. I need to check the exact figure, but I know that SpeedFusion will always favour the lowest latency link available and will not use a WAN link that has very high comparative latency to the lowest latency link in use. Depending on the stream characteristics we might need to get creative about how we make best use of your WANs. For example you could VPN bond the LTE links and send one stream that way, and then do another async VPN bonded tunnel to lower the apparent latency of the vSAT and use that for the other streams…

Really interested to better understand your application to see what options there might be.



Hi Martin,
It is a single HD H.264 feed from remote TV production site to studio 1080i50.
No way to split it, need to use bonding.