It is very important to understand how network traffic flows work as it can impact your billing. The general rule of thumb is that the following traffic is free:
- Ingress traffic
- Egress within the same zones using internal IPs
- Egress to a different GCP service within the same region using an external IP address or an internal IP address
This free traffic does not include a number of services that haven't mentioned in this book yet: Cloud Memorystore for Redis, Cloud Filestore, and Cloud SQL.
The following traffic is charged for:
- Egress between zones within the regions
- Egress between regions
- Internet egress