A service provider should be able to remotely maintain certain systems on the LAN. For this purpose, a VPN is established between the service provider's network (10.8.0.0/16 in the example) and the LAN. To avoid conflicts with the service provider, the service provider specifies a certain network area for the LAN, in this case 10.7.3.0/24.
However, the local network is already configured to another network, in the example 192.168.1.0/24, so that the local network does not have to be completely converted, the local network is rewritten to the specified IPs for this one VPN connection.
