I'm using ISP router modem to have an internet access. So it manages the 192.168.1.0/24 sub-network and provide internet access. I have linked the MPC8308NSG WAN interface to this router. As network.png figure shows; I have accorded to it the 192.168.1.96 address. And it will manages the 192.168.2.0/24 sub-network. Other linked figures show its firewall and routing table configurations.
I have linked a PC to MPC8308NSG LAN and I have tested internet access. the result is negative; any device in MPC8308NSG LAN cannot have see any address not in 192.168.2.0/24 sub-network.