When you created your VPC networks, GCP automatically created several route tables. You must create one additional route table, which will allow the protected network to use the FortiGates as the default gateway.
- In the GCP console, click the primary FortiGate's instance details and note the IP address assigned to the protected network interface, nic1 if you followed the order of interface creation previously covered in this guide.
- Go to VPC Networks > Routes, then click CREATE ROUTE.
- In the Name field, enter the route table name.
- From the Network dropdown list, select the protected network.
- In the Destination field, enter 0.0.0.0/0.
- In the Priority field, enter 10. You can set this to any number less than 1000, which is the default priority for the GCP default route table. This ensures you route all traffic from the protected network through the FortiGate before leaving the VPC.
- From the Next hop dropdown list, select Specify an IP address.
- In the Next hop IP address field, enter the IP address of the FortiGate interface assigned to the protected network. In this example, the IP address is 10.0.2.13, but your IP address may be different.
- Click Create.