This method works by configuring the source database server to accept connections from the outgoing IP of the Cloud SQL instance.

If you choose this method, then Database Migration Service guides you through the setup process during the migration creation.

• Easy to configure.
• Doesn't require any custom firewall configuration.
• Recommended for short-lived migration scenarios (POC or small database migrations).

• Network traffic occurs over the public Internet.
• Less secure.
• Decreased performance.

Establishes connectivity from the destination to the source through a secure reverse SSH tunnel.

Requires a bastion host VM in the Google Cloud Platform project as well as a machine (for example, a laptop on the network) that has connectivity to the source.

Database Migration Service collects the required information at migration creation time, and auto-generates the script for setting it all up.

• Easy to configure.
• Doesn't require any custom firewall configuration.
• Recommended for short-lived migration scenarios (POC or small database migrations).

• The bastion VM is owned and managed by you, and may incur additional costs.

This method works by configuring the VPCs to communicate with one another.

• Native Google Cloud solution.
• Easy to configure.
• High bandwidth.
• Recommended for long-running or high-volume migrations.

• Applicable if both the source and destination databases are hosted in Google Cloud, or if the source is connected to the destination VPC using a VPN (cloud-hosted or on-premises) or Cloud Interconnect.