Fortinet FortiGate 400, Installation & Configuration Manual, Page: 55 / 308

NAT/Route mode installation Configuration example: Multiple connections to the Internet
FortiGate-400 Installation and Configuration Guide
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Load sharing
You can also configure destination routing to direct traffic through both gateways at
the same time. If users on your internal network connect to the networks of ISP1 and
ISP2, you can add routes for each of these destinations. Each route can include a
backup destination to the network of the other ISP.
The first route directs all traffic destined for the 100.100.100.0 network out port2 to
gateway 1 with the IP address 1.1.1.1. If this router is down, traffic destined for the
100.100.100.0 network is re-directed out port3 to gateway 2 with the IP address
2.2.2.1.
Load sharing and primary and secondary connections
You can combine these routes into a more complete multiple internet connection
configuration. In the topology shown in
Figure 8 on page 53 , users on the internal
network would connect to the Internet to access web pages and other Internet
resources. However, they may also connect to services, such as email, provided by
their ISPs. You can combine the routes described in the previous examples to provide
users with a primary and backup connection to the Internet, while at the same time
routing traffic to each ISP network as required.
The routing described below allows a user on the internal network to connect to the
Internet through gateway 1 and ISP1. At the same time, this user can also connect
through to gateway 2 to access a mail server maintained by ISP2.
Adding the routes using the web-based manager
1 Go to System > Network > Routing Table .
2 Select New to add the default route for primary and backup links to the Internet.
• Destination IP: 0.0.0.0
• Mask: 0.0.0.0
• Gateway #1: 1.1.1.1
• Gateway #2: 2.2.2.1
• Device #1: port2
• Device #2: port3
• Select OK.
Table 12: Load sharing routes
Destination IP‘ Mask Gateway #1 Device #1 Gateway #2 Device #2
100.100.100.0 255.255.255.0 1.1.1.1 port2 2.2.2.1 port3
200.200.200.0 255.255.255.0 2.2.2.1 port3 1.1.1.1 port2