I have an ISR 4451, in a very remote area, that is only serviced by one ISP, who provides IP addresses via DHCP based on MAC, and offers subscriptions of limited speed and limited monthly throughput.
For this reason, we find ourselves wanting to get multiple subscriptions, which would result in all three connections using the same next hop, same subnet, essentially same network. We'd like to be able to set up multiple VLANs and direct each vlan to use a specific connection/interface. However, as you can imagine, setting this up on the router creates overlapping networks for the WAN connections.
I've been modeling the scenario by using a simple EdgeRouter with a DHCP service and a switch to proxy for the ISP until I get a solution figured out to test on their network. In this way, I can keep this thing off the Internet until ready and can reproduce the behavior of the ISP.
I've read a lot of questions about using multiple Internet connections with one router, and (for good reason) many assume you're using multiple ISPs, and this seems rather straight forward as the ISPs have different networks respectively.
I've tried creating subinterfaces with different native VLAN IDs, thinking maybe there's be some isolation in the routing table, but it still won't allow me to have overlapping networks on multiple interfaces even on separate, theoretically isolated, interfaces.
I've explored some BGP options but it seems I would need control over the far-end router(s) as well as my own, which just isn't the case here.
I believe I understand why I'm running into this problem, and understand it's an unorthodox scenario, but am wondering if there's a workaround/protocol/technology for this. I was hoping the ISR would be able to pull something like this off, but I don't know what I don't know - are there more advanced routing protocols or configurations that would provide the isolation necessary to achieve this? Does it really require three discrete routers to pull this off?
Thank you for any help you can offer, it's very much appreciated.
