Fortinet FortiGate 100 - Manual (Page 54)

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Policy routing examples NAT/Route mode installation
Policy routing examples
Policy routing can be added to increase the control you have over how packets are
routed. Policy routing works on top of destination-based routing. This means you
should configure destination-based routing first and then build policy routing on top to
increase the control provided by destination-based routing.
For example, if you have used destination-based routing to configure routing for dual
internet connections, you can use policy routing to apply more control to which traffic
is sent to which destination route. This section describes the following policy routing
examples, based on topology similar to that shown in
Figure 8 on page 50 .
Differences are noted in each example.
The policy routes described in these examples only work if you have already defined
destination routes similar to those described in the previous section.
• Routing traffic from internal subnets to different external networks
• Routing a service to an external network
For more information about policy routing, see “Policy routing” on page 118 .
Routing traffic from internal subnets to different external networks
If the FortiGate unit provides internet access for multiple internal subnets, you can use
policy routing to control the route that traffic from each network takes to the Internet.
For example, if the internal network includes the subnets 192.168.10.0 and
192.168.20.0 you can enter the following policy routes:
1 Enter the following command to route traffic from the 192.168.10.0 subnet to the
100.100.100.0 external network:
set system route policy 1 src 192.168.10.0 255.255.255.0 dst
100.100.100.0 255.255.255.0 gw 1.1.1.1
2 Enter the following command to route traffic from the 192.168.20.0 subnet to the
200.200.200.0 external network:
set system route policy 2 src 192.168.20.0 255.255.255.0 dst
200.200.200.0 255.255.255.0 gw 2.2.2.1
Routing a service to an external network
You can use the following policy routes to direct all HTTP traffic (using port 80) to one
external network and all other traffic to the other external network.
1 Enter the following command to route all HTTP traffic using port 80 to the next hop
gateway with IP address 1.1.1.1.
set system route policy 1 src 0.0.0.0 0.0.0.0 dst 0.0.0.0
0.0.0.0 protocol 6 port 1 1000 gw 1.1.1.1
2 Enter the following command to route all other traffic to the next hop gateway with IP
address 2.2.2.1.
Set system route policy 2 src 0.0.0.0 0.0.0.0 dst 0.0.0.0
0.0.0.0 gw 2.2.2.1