Bandwidth Bonding?

Everything Else
1

I’m testing a Speedfusion setup, and I was hoping to see bandwidth bonding, but it’s not obviously working.

I have two B20x units, one with a fast connection, and a remote one with two slow connections. I was hoping to see an increase in usable download bandwidth with the remote unit.

The remote connections each top out at 9.7Mb/s, I’ve set the Speedfusion VPN profile to do bonding (Dynamic weighted). I’m still only seeing 9Mb/s or so downloads. This is using the usual Speedtest.net test.

What’s confusing is the local unit is showing 20Mb/s upload, and each of the bonded remote connections is showing 10Mb/s each. So this 9Mb/s is using 20Mb/s.

Also the upload from the remote is showing 16Mb/s, which is more like I was hoping for.

What am I missing here?

2

Hi!

For bandwidth testing on SpeedFusion links we usually recommend using the integrated bandwidth testing tool, which can be found in the Web Admin here:

Screenshot 2025-04-17 at 13.46.33
Screenshot 2025-04-17 at 13.46.331012×477 56.8 KB

Now on what bandwidth should actually be expected:

  • Due to the additional overhead of SpeedFusion, two identical WAN links bonded should have a throughput of up to 1.6 times that of a single WAN link.
  • If the two WAN links are cellular connections and are using the same base station - then they may compete with each other for bandwidth and not actually produce a higher throughput when bonding.
  • Some SpeedFusion features (e.g. WAN Smoothing, FEC, etc.) when enabled can limit the throughput of the SpeedFusion tunnel.
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3

I want to echo this point specifically. In places where you’re bonding due to heavy congestion, this point is the reason that you need to use diverse carriers.

4

Speedtest and the built in test are giving me much the same results (most of the time, see below).

I had FEC and WAN Smoothing on. I had checked that, but I’d turned it on on the other end, and didn’t notice. With those on, each link would only run at 44% of the bandwidth.

Without those, 2 links is giving me 1.8x the bandwidth, 16.7Mb/s which is the sort of thing I’m looking for.

However, 3 links is only giving me 1.3x as much 22.2Mb/s, and Speedtest isn’t showing any improvement with the 3rd link. It’s not managing to saturate the 3rd link.

I think this may be running into the limitations of the B20x units, which are a bit slow. I may get better throughput with B One units. (Which is strange, as the B Ones are supposedly lower end.)