You are migrating your on-premises solution to Google Cloud in several phases. You will use Cloud VPN to maintain a connection between your on-premises systems and Google Cloud until the migration is completed. You want to make sure all your on-premise systems remain reachable during this period. How should you organize your networking in Google Cloud?

When connecting on-premises networks to Google Cloud via Cloud VPN, it is crucial to use non-overlapping IP address ranges. If both networks use the same IP range, routing conflicts will occur, preventing communication between systems in the two environments. This is because routers would not know whether a destination IP address refers to a resource in the on-premises network or in Google Cloud. Therefore, assigning a unique, non-overlapping IP range in Google Cloud ensures that all on-premises systems remain reachable and that traffic is routed correctly. Using the same IP range, even partially, will lead to connectivity issues.