Configuring the SD-WAN to steer traffic between the overlays

Configure the HQ FortiGate to use two overlay tunnels for SD-WAN, steering HTTPS and HTTP traffic through the FGT_AWS_Tun tunnel, and SSH and FTP throguh the AWS_VPG tunnel.

1. Add SD-WAN member interfaces

2. Configure a route to the remote network

3. Configure firewall policies

4. Configure a health check

5. Configure SD-WAN rules

To add SD-WAN member interfaces:

1. Go to Network > SD-WAN, select the SD-WAN Zones tab, and click Create New > SD-WAN Member.

2. Set Interface to AWS_VPG then click OK.

   

3. Click Create New > SD-WAN Member again.

4. Set Interface to FGT_AWS_Tun.

5. Set Gateway to 172.16.200.1.

6. Click OK.

   

To configure a route to the remote network 10.0.2.0/24:

1. Go to Network > Static Routes and click Create New.

2. Set Destination to Subnet and enter the IP address and netmask: 10.0.2.0/255.255.255.0.

3. Set Interface to virtual-wan-link.

   

4. Click OK.

   Individual routes to each tunnel are automatically added to the routing table with the same distance:

   

To configure firewall policies to allow traffic from the internal subnet to SD-WAN:

1. Go to Policy & Objects > Firewall Policy and click Create New.

2. Configure the following:

   Name	ISFW-to-IaaS
   Incoming Interface	port3
   Outgoing Interface	virtual-wan-link
   Source	all
   Destination	all
   Schedule	always
   Service	ALL
   Action	ACCEPT
   NAT	Enabled

3. Configure the remaining settings as required.

4. Click OK.

   Once the firewall policies are configured, the VPN tunnels should come up when there is traffic.

To configure a health check to monitor the status of the tunnels:

As you are accessing the servers on the 10.0.2.0/24 subnet, it is preferable to use the FortiGate port2 interface as the ping server for detection. This ensures that, if the gateway is not reachable in either tunnel, its routes are brought down and traffic continues on the other tunnel.

1. Go to Network > SD-WAN, select the Performance SLAs tab, and click Create New.

2. Configure the following:

   Name	ping_AWS_Gateway
   Protocol	Ping
   Server	10.0.2.10
   Participants	Specify Add AWS_VPG and FGT_AWS_Tun as participants.

   

3. Click OK.

   

   Health check probes originate from the VPN interface's IP address. This is why the phase2 selectors are configured with Local Address set to all.

To configure SD-WAN rules to steer traffic:

HTTPS and HTTP traffic is steered to the FGT_AWS_Tun tunnel, and SSH and FTP traffic is steered to the AWS_VPG tunnel. The Manual algorithm is used in this example.

1. Go to Network > SD-WAN, select the SD-WAN Rules tab, and click Create New.

2. Configure the following:

   Name	http-to-FGT_AWS_Tun
   Source Address	all
   Address	remote_subnet_10_0_2_0
   Protocol	TCP
   Port range	80 - 80
   Outgoing Interfaces	Manual
   Interface preference	FGT_AWS_Tun

3. Click OK.

4. Create other SD-WAN rules as required: