4x FO connections to a load balancer but not working when using secure connexion

Perhaps you can help us find the right equipment.
We have a Tplink tl-r480t+ load balancer with 4x 20Mbps upload optical routers connected to it.
The www.speedtest.net gives out a 79Mbps upload result which is excellent… but when using a software that uses a secured connexion (eg Aspera) we only get 19 Mbps (the equivalent of only one line).
Strangely enough, when we connect 2 computers to the Tplink, we get 19 Mbps on each one concurrently but never more. But If I use a ftp software I can get the 79 Mbps guessing it doesn’t use a secure line.
How can I get the sum of all 4 lines on upload using a secure connexion ?
Would you sale a product that would be able to do that ?
Thank you in advance for helping find the right load balancer,

Hi dinosigma,

Loadbalancing does not combine multiple WAN connections into one high speed link.
Loadbalancing is used for steering traffic over multiple WAN connections, while still using them seperately.

If you would connect four 20 Mbps WAN connections to a Peplink device, you will also get 80 Mbps as a Speedtest result.
Your software can only use only one WAN connection at the same time, thus giving you a 19 Mbps result.

If you would like to combine the four WAN connections into one high speed link, you will need to implement Peplink’s SpeedFusion Bandwidth Bonding solution.
This requires you to set up a VPN tunnel between two Peplink devices, in which the four WAN connections will be bonded to one high speed link.
Keep in mind that if you’re going to combine four 20 Mbps WAN connections, you will need a WAN connection with atleast 80 Mbps speeds on the other end of the SpeedFusion Bandwidth Bonding VPN tunnel.
This could be a datacenter for example.

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Thank you Joey for your prompt response,
I get confuse when you say “Your software can only use only one WAN connection at the same time” because when we use a ftp software we do get the 80Mbps on the upload thus combining all four 20Mbps connections. The problem only occurs when we try to use a secure connection. Unfortunately ftp is no longer a standard when transferring large files. So I don’t think it is Aspera software that is using only 1 line but rather the hardware that is forcing it to.
I don’t understand why you need 2 Peplink devices ? Why not just one that would do the trick ? Hope you are not thinking of having the second one, on our clients’ end. They usually have their servers ready to receive the 80Mbps upload from us and would only provide us with an username and password to send the files (we are sending video files) usually using Aspera as their main software.
Which Peplink device should I look into ?

I might have misunderstood your setup.
@MartinLangmaid, can you jump in on this?


Hi. I think @Joey_van_der_Gaag is exactly correct. The “piece” that may be missing is this: The reason you were able to achieve 79Mb/sec with Speedtest.net is that this service uses multiple streams. Therefore it is possible all WANS were in use and the throughput was summed across those WANs. The reason you were able to get only 19 to each of two computers is that no summing was taking place as there was likely a single session in play from/to each machine.

The reason you’d need a second Peplink device for “speed fusion” is that this feature operates between appropriate Peplink devices (or services). There are a number of whitepapers and “explainers” on the Peplink web site show how this works. The 2nd such device (or VM/instance) would typically be located in a data center with network sufficient capacity. See https://www.peplink.com/products/fusionhub/ .

Does that help?


This article might help.


Thank you Rick for your clear answer.
Unfortunately, I do not have the possibility to impose any devices to our clients. They are usually Data Centers that just provide us with access to their servers to upload files there. I have to find a solution that allows us to use the sum of all the WAN connections, just like the solution I have now that works with ftp software but not other software that uses secure connection such as Aspera that uses a secure connection that prevents this summing.

So what you’re seeing on your Tplink tl-r480t+ load balancer is session based load balancing.

When applications communicate across a network they generally use UDP/TCP sessions (or connections) between the devices that are sending data. In the case of speedtest.net their client uses multiple (4 on last check) sessions simultaneously to try and saturate your available internet connectivity to see how much bandwidth you have.

Your TPLink is doing its job well by all accounts as when the speedtest.net sessions are created it is load balancing those across your 4 available links so you get near full line speeds up (the 79Mbps).

Your FTP software is doing a similar thing, creating multiple sessions for file transfer that also get load balanced across the available links. Not all FTP software does this - some only ever use a single session (for example when you are encrypting the FTP traffic) and if you were using such a FTP client, you would only see a maximum of 20Mbps of upload bandwidth (the limit on one link) as a session can only consume the bandwidth available on the WAN link it is currently using (single session’s can not be split across multiple WANs without additional technology).

For a single session to be able to saturate the available bandwidth from multiple WAN links it needs to be broken down into its constituent packets and then those packets can be distributed across the links. At the other end those packets have to be put back together again to recreate the contents of the original session. This is what SpeedFusion Bonding does.

To use SpeedFusion Bonding you need a SF enabled Peplink device in your office (to deconstruct the session and spread it across the WAN links) and a SF enabled appliance somewhere on the internet to re construct the session and forward on to the ultimate destination.

Many Peplink users do this using a FusionHub which is a virtual appliance that you install in the cloud that reconstructs sessions to and from your appliance in your office forwarding the traffic on from the cloud to its ultimate destination (websites, customer networks FTP servers etc).

SpeedFusion Bonding is a VPN technology and so there is an overhead to using it (it requires additional data to be sent to work and so consumes a little bandwidth itself). Typically you would see 15-20% loss of total bandwidth in that overhead.


Here is a diagram explaining how the SpeedFusion process works (in the case for a single IP CCTV Video stream/session).
You can replace the Datacenter Balance Router with a FusionHub Virtual Appliance hosted just about anywhere online in the Cloud.

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First I want to thank you, Martin, for taking the time to layout your answers.
Forgive me for not being very technical, but in your first answer you seemed to hint that there is an option on the cloud for not using the SpeedFusion on both end (as I said I can only setup hardware on my end). Is that correct ?

You’re welcome.

Yes thats right. You would have a Peplink hardware device at your location, it would have the 4 wans connected and act as your gateway -splitting the sessions into four separate streams of traffic.

Then you could host a Fusionhub virtual appliance in the cloud that all of your internet traffic would be sent via. Its job is to both rebuild the sessions for your transmitted traffic (your uploads to online services) and split your sessions from online services (Your downloads) into separate streams to send back down to you.

Your upload and download traffic for internet access gets tunnelled in and out of that virtual appliance in the cloud - giving you bandwidth aggregation (upload and download) and resilience (in case a WAN link fails).

There are lots of partners on here that can help you source the Peplink hardware and assist with the Cloud hosted bit too. If you let us know where you are based geographically we can poke one of them to contact you.

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We are based in Casablanca, Morocco. Do you think someone locally can help us set it up ?
Thanks again

Please check the certified partner list here:

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