Multiple cellular connections need to be aggregated on different boxes (seperated some miles away) to achieve the upload bandwidth required and to guarantee connection availability
Clients------------------ Clients
Box-1 ------------------ Box-2
LTE-1 ISP ------------ LTE-3 ISP
LTE-2 ISP------------- LTE-4 ISP
I’m not sure what your box is referring to, but if it’s referring to one of our products, that’ll be one of our core technology and advantages, SpeedFusion.
Balance 580 with multiple HD4 connected
I assume what you meant is HQ is running on a Balance 580, with multiple sites connecting back to HQ via HD4s?
If I’m right, just setup SpeedFusion between your Balance 580 and the sites and you should be good to go.
A Balance 580 will be able to support up to 50 tunnels.
The purpose is to bound ISP LTE connections together that are spread some miles away to one internet connection. Kind of backbone.
Connecting the remote wan links over dedicated Wi-Fi links. If one ISP LTE mast goes down we still need connection to the internet on the backbone.
Do you meant to have Peplink load-balance out of all 4 LTE connections (2 local and 2 remote location)?
Yes, indeed.
I did a sketch of a possible scenario.
This is the closest we can get, by using 2 pair of PTP access points.
The biggest problem will be the possibility of a loop occurring, when the LTEs are all down.
I suppose in your drawing you are using several (HD4 with LTE coupled with Wi-Fi link) to one Balance 580 will be no problem.
So all the LTE ISP internet connections are bounded to one big Internet trunk.
Not really. My drawing consist only of 2 HD4s, with LTE connecting directly to it.
HD4 is also capable of WiFi WAN, hence each of them will be connected to 2 LTEs, and a WiFi WAN.
I’m still not too sure how 580 fit into your scenario though.
Edit: If VPN is involved though, this setup won’t be feasible.
The Wi-Fi link is only to extend the distance between the HD4 and Balance 580.
Yes, the PTP is only to extend the distance, but looping is still a possibility in that setup that you have to consider.
Of course, the PTP link itself is another issue altogether, depending on your LoS, distance, etc.
how can you have a loop ? The PTP Wi-FI link replaces only a normal utp cable ?
Based on the diagram I share, that PTP link is connected from WAN to LAN, same for the other side.
Assuming all the LTEs are down, this link has no way to determine that, because based on that setup this 2 PTP links are always up.
Maybe we’re looking at a wrong solution altogether.
Something has been on my mind so far though, regarding how your 580 comes into the picture.
You mentioned between that you have multiple HD4s with 580. Is this referring to a single location, whereby you have a single Balance 580 connected to a few MAX HD4? Personally though, if you have a setup like this with say 1x 580 and 2x HD4, we’re talking about the possibility of having 8 active LTE connections. A scenario where all the LTE fails only happen in movie in my book. 
However, if that’s the case and you want some form of load-balancing to happen between different location, maybe something like the following will suit your need.
See the attachment. Will clarify the setup.
I assume there’s a reason you need to do PTP over long distance to connect, but your diagram looks feasible.
Sizing of the models will depend on what & amount of traffic going through though.
