Use VPN over LTE as backup for layer 2 line.

Hi,

there are already some posts with great explainations regarding VPN as a backuo for MPLS or layer 2 links.

My situation is slightly different and I would appreciate if anybody has an idea for a best practise solution.

There are two UTMs. One in an office and one in a data center.

The office has no local internet access for regular usage but is linked via a layer 2 connection to the data center. All traffic goes through Layer 2 link from office to dc. Including internet.

The office has a LTE router with limited but sufficient monthly traffic to set up an emergency use VPN if layer 2 connection goes down.

There is no need to route any internet traffic to local ISP in office. From datacenter only traffic to office should be routed to office. No need to use office LTE internet in any case from dc.

Office Lan is 10.0.20.0/24 with interface 10.0.20.1 on UTM2. Uplink interface as default gw with 10.0.100.3/30 connected to Layer 2 link. Interface LTE with 192.168.0.2/24 is linked to LTE router.

Datacenter Lan is 10.0.10.0/24 with interface 10.0.10.1 on UTM1. Interface 10.0.100.2/30 connected to Layer 2 link. Interface Internet with certainpublicip is linked to datacenter ISP.

Thanks in advance!

Kind regards

Philipp