This page provides a high-level overview of what you need to consider when you plan network connectivity for your migration.
From a networking point of view, Database Migration Service and Cloud SQL are service producers that reside in their own dedicated networks (known as service networks), outside the Virtual Private Cloud (VPC) networks that you use in your Google Cloud project.
For homogeneous MySQL migrations to Cloud SQL, Database Migration Service connects to the destination Cloud SQL instance and then manages the migration process on its behalf. It's the destination instance that establishes the connection to your source instance, but Database Migration Service oversees the process. The goal of configuring network connectivity for a migration process is to ensure that the destination Cloud SQL can reach your source database server over the network.
Different connectivity methods are available for different source database offerings and destination Cloud SQL for MySQL configurations. Before you configure your source instance for the migration, we recommend that you consider what networking methods you can use to establish the necessary connections. See the Networking overview page to understand the end-to-end networking landscape for Database Migration Service migrations.
What's next
For complete, step-by-step migration walkthroughs, see Get started with Cloud SQL for MySQL migrations.