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Anonymous_User
Contributor
December 17, 2008
Question

Dual WAN w/same Gateway for both- won' t let me do it

  • December 17, 2008
  • 2 replies
  • 3623 views
I have 2x 4MB/4MB lines coming into our office. Previously I had a Linksys RV042 and had no issues with the lines hooking up at all. Example: External IP 1: 1.1.1.130 External IP 2: 1.1.1.171 Gateway for both: 1.1.1.129 Subnet for both: 255.255.255.128 These settings are verified when using DHCP (the IP is a static external IP, that is reserved on the ISP' s DHCP server). If I have one of the WAN addresses plugged in manually OR over DHCP, and then attempt to install the 2nd WAN address manually I get this error: " IP address is in same subnet as the others." The router currently has 1 static route in place (but it is the same when I have the same entry for WAN2)... IP/Mask: 0.0.0.0/0.0.0.0 Gateway: 1.1.1.129 Device: WAN1 Distance: 10 In the Monitor Tab I have this: Type: Static Network 0.0.0.0/0 Gateway: 1.1.1.129 Interface: WAN1 Type: Connected Network: 10.1.1.0/24 Gateway: 0.0.0.0 Interface: Internal Type: Connected Network: 1.1.1.128/25 Gateway: 0.0.0.0 Interface: WAN1 I just can not seem to get the 2nd WAN device installed, and I want it setup with manual entries so I can setup HA Active-Active and route half of the Internet IP' s out one WAN and the other half out the 2nd WAN' s IP. Thoughts?

    2 replies

    nsumner
    nsumner
    New Member
    December 21, 2008
    Hi this is actually an easy one! The Fortigate by default does not allow subnets to overlap but you can change that. Of course be warned it is easy to do damage by changing this setting if you mess up the routing tables. In any event: You must connect to the CLI of the Fortigate. Personally I have come to the point with my Fortigate the only thing I do is look at the order of rules through the GUI (it is just better for seeing a quick summary of all the rules and the order they fall in). Connect using the CLI type ' config system settings' now type ' allow-subnet-overlap' now ' end' now ' exit' you should now be able to create both connections without a problem!
    support12
    support12
    New Member
    December 24, 2008
    More clean configuration is enable vdom. Create a vdom and route thru vdom-link. Because overlap subnet is not a network standard.
    A
    Anonymous_UserAuthor
    Contributor
    January 16, 2009
    Hi, can any one help me with the step by step instructions on how to setup a load balancing/fail over using the vdom? Thanks in advance.
    nsumner
    nsumner
    New Member
    December 25, 2008
    You could certainly do this through VDOMs as well. The cleanest way would be using 3 vdoms (1 for each wan interface, and 1 internal) but you could also do it with 2. (1 for 1 wan, the second for everything else). From a technical perspective it is certainly cleaner, however from a management perspective it is a bigger pain. Might be best to start with allow-subnet-overlap and if that gives you trouble go the VDOM route.
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