Centralized east-west, inter-VPC Example

Scenario objective

Traffic between two VPCs, VPC A and VPC B, is inspected by a FortiGate CNF instance.

Before deployment of FortiGate CNF

In this scenario, traffic is between two VPCs, VPC A and VPC B, through a transit gateway.

The Before deployment of FortiGate CNF traffic flow is as follows:

1. Traffic originates from Private Subnet (10.2.3.0/24) in VPC A (10.2.0.0/16) and goes to the AWS Transit Gateway located in TGW Subnet (10.1.6.0/24) in Inspection VPC (10.1.0.0/16).

2. AWS Transit Gateway sends the traffic to Private Subnet (10.3.3.0/24) in VPC B (10.3.0.0/16).

Routing tables

The routing tables are defined as follows.

Private Subnet (VPC A) route table

Destination	Target
10.2.0.0/16	Local
0.0.0.0/0	AWS Transit Gateway

Private Subnet AWS Transit Gateway (VPC A) route table

Destination	Target
0.0.0.0/0	Inspection VPC

Private Subnet (VPC B) route table

Destination	Target
10.3.0.0/16	Local
0.0.0.0/0	AWS Transit Gateway

Private Subnet AWS Transit Gateway (VPC B) route table

Destination	Target
0.0.0.0/0	Inspection VPC

TGW Subnet route table

Destination	Target
10.1.0.0/16	Local

AWS Transit Gateway route table

Destination	Target
10.2.0.0/16	VPC A
10.3.0.0/16	VPC B

After deployment of FortiGate CNF

The After deployment of FortiGate CNF traffic flow is as follows:

1. Traffic originates from Private Subnet (10.2.3.0/24) in VPC A (10.2.0.0/16) and goes to the AWS Transit Gateway located in TGW Subnet (10.1.6.0/24) in Inspection VPC (10.1.0.0/16).

2. AWS Transit Gateway sends the traffic to the GWLBe located in CNF Endpoint Subnet (10.1.1.0/24).

3. Traffic is sent to the FortiGate CNF instance for inspection.

4. FortiGate CNF sends traffic back to the GWLBe.

5. GWLBe sends the traffic to AWS Transit Gatway.

6. AWS Transit Gateway forwards the traffic on to Private Subnet (10.3.3.0/24) in VPC B (10.3.0.0/16).

To deploy the FortiGate CNF instance in this scenario:

1. In AWS, add a subnet CNF Endpoint Subnet in Inspection VPC along with the associated route table.

   Destination	Target
   10.1.0.0/16	Local
   0.0.0.0/0	NAT Gateway
   10.0.0.0/8	AWS Transit Gateway

2. In FortiGate CNF, deploy a GWLBe to this subnet.

3. In AWS, add a route to the Transit Gateway Subnet route table to route all traffic to the GWLBe.

   Destination	Target
   10.1.0.0/16	Local
   0.0.0.0/8	GWLBe