Introduction
As enterprises move to cloud there is a need to connect cloud-native applications with on-premise legacy systems. Multi-Cloud architectures allow you to build solutions spanning more than one public cloud by combining best of breed capabilities creating an increasing need for interconnecting these clouds. For example, you may want to use the Google App Engine to deploy your app but for your backend prefer Oracle ATP database hosted on Oracle Cloud.
Each public cloud provides multiple connectivity options from dedicated high speed interconnect to using VPN based technologies to connect to on-premise using IPSec based connections that use public internet but provide secure connectivity.
Oracle OCI offers service called VPN Connect for site-to-site connectivity between an on-premise network with OCI VCN using VPN based on the IPSec protocol.
In this blog, I will outline steps for configuring VPN between Oracle OCI Private Subnet with Google GCP VPC. VPN using IPSec is a cost-effective way of connecting these networks over public internet obviating no need for expensive lease lines and such. Steps outlined here also apply if you are trying to connect your on-premise network with either of these two cloud service providers.
Note that I will focus on Site-to-Site connectivity based on IPSec protocol and use out-of-the-box functionality for VPN provided by these two cloud providers. You can also use other VPN implementations such as open-source Strongswan and Libreswan.
