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RedMt
RedMt
New Member
March 17, 2017
Question

Multiple default routes across multiple interfaces

  • March 17, 2017
  • 1 reply
  • 34360 views

Hello,

 

I've an interesting routing situation at one of my facilities using a Fortigate 300D on firmware v5.2.10, and I'm hoping someone here can help me with it.

 

We recently set up a second ISP at this facility, and put it on its own interface on the firewall. Let's call these 2 ISP interfaces WAN1 and WAN2. LAN / production traffic comes in on another interface while Guest network traffic comes in on yet another interface. Let's call those interfaces LAN1 and GST1.

 

I want all traffic from GST1 to use a default route pointing over WAN2 for internet traffic, while LAN1 uses a default route pointing over WAN1 for its internet. Additionally, it would be ideal if LAN1 would failover to WAN1 if WAN2 goes down, with LAN1 receiving a guaranteed higher priority than GST1 traffic in that failover scenario. GST1 does not need to fail over if WAN1 goes down.

 

Is this possible? If so, how do I set this up? I've attempted using link health monitoring and policy-based routing to create multiple default routes but I must be missing something, as I've not been able to get it working. If I had to guess, it's because I'm missing something in the policy based routing setup. I've not used that before, while I use the link health monitor in multiple other facilities / firewalls.

 

Thanks in advance for any advice.

    1 reply

    RedMt
    RedMtAuthor
    New Member
    March 23, 2017

    Friendly bump

    tanr
    tanr
    New Member
    March 23, 2017

    You can have two (or more) default static routes, but they must both have the *same* distance, but with different priorities.  That way they both stay in the routing table and the policy route can force you to one or the other interface.   Some documentation:   http://kb.fortinet.com/kb/viewContent.do?externalId=FD32103  http://kb.fortinet.com/kb/documentLink.do?externalID=FD36462  http://kb.fortinet.com/kb/documentLink.do?externalID=100116  

    MikePruett
    MikePruett
    New Member
    March 23, 2017

    Priority of a route in FortiOS is the equivalent of "cost" on other devices. You can have as many default routes as you want and they have the same distance but varying priorities.

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