D-Link DFL-860-IPS-12 Product Manual - Page 163
The Ordering parameter, Example 4.5. Policy-based Routing Configuration
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4.3.5. The Ordering parameter Chapter 4. Routing Example 4.5. Policy-based Routing Configuration This example illustrates a multiple ISP scenario which is a common use of Policy-based Routing. The following is assumed: • Each ISP will give you an IP network from its network range. We will assume a 2-ISP scenario, with the network 10.10.10.0/24 belonging to ISP A and 20.20.20.0/24 belonging to ISP B. The ISP gateways are 10.10.10.1 and 20.20.20.1 respectively. • All addresses in this scenario are public addresses for the sake of simplicity. • This is a "drop-in" design, where there are no explicit routing subnets between the ISP gateways and the NetDefend Firewall. In a provider-independent network, clients will likely have a single IP address, belonging to one of the ISPs. In a single-organization scenario, publicly accessible servers will be configured with two separate IP addresses: one from each ISP. However, this difference does not matter for the policy routing setup itself. Note that, for a single organization, Internet connectivity through multiple ISPs is normally best done with the BGP protocol, where you do not need to worry about different IP spans or policy routing. Unfortunately, this is not always possible, and this is where Policy Based Routing becomes a necessity. We will set up the main routing table to use ISP A and add a named routing table called r2 that uses the default gateway of ISP B. Interface lan1 lan1 wan1 wan2 wan1 Network 10.10.10.0/24 20.20.20.0/24 10.10.10.1/32 20.20.20.1/32 all-nets Gateway 10.10.10.1 ProxyARP wan1 wan2 lan1 lan1 Contents of the named Policy-based Routing table r2: Interface wan2 Network all-nets Gateway 20.20.20.1 The table r2 has its Ordering parameter set to Default, which means that it will only be consulted if the main routing table lookup matches the default route (all-nets). Contents of the Policy-based Routing Policy: Source Interface lan1 wan2 Source Range 10.10.10.0/24 all-nets Destination Interface wan2 lan1 Destination Range all-nets 20.20.20.0/24 Selected/ Service ALL ALL Forward VR table r2 r2 Return VR table r2 r2 To configure this example scenario: Web Interface 1. Add the routes found in the list of routes in the main routing table, as shown earlier. 2. Create a routing table called "r2" and make sure the ordering is set to "Default". 3. Add the route found in the list of routes in the routing table "r2", as shown earlier. 4. Add two VR policies according to the list of policies shown earlier. • Go to Routing > Routing Rules > Add > Routing Rule • Enter the information found in the list of policies displayed earlier • Repeat the above to add the second rule 163