Skip to main content
BK_Bianko
BK_Bianko
Visitor III
April 2, 2014
Question

Change WAN interface from static IP to PPPoE causes routing issues

  • April 2, 2014
  • 3 replies
  • 15016 views
Hi at all, I have a strange problem. I have two connectivities to internet. One goes in a Bintec router and one goes in WAN2 port of my Fortigate 110C. This connectivity goes directly into WAN2 port of my fortigate 110C. An Ethernet port of the Bintec is connected to WAN1 port of the Fortigate. Anything is always gone fine. I have two default routes with same distance towards the two connetctivities. I have two policy routes, one that routes all non-lan traffic to WAN2 and the other one routes SMTP traffic through WAN1. My internet provider changed the WAN2 connectivity from a ATM static IP to a PPPoE. Ok, I' ve changed interface to PPPoE, set obtain gateway from ISP, put username and password and connectivity is established. Then I changed VIPs that mapped the new external IP to internal IPs accordingly. I changed the default route with new external gateway. After doing all these things internet browsing through WAN2 works but I' ve lost connectivity from outside to WAN1 interface and e-mails that before gone through either WAN1 or WAN 2 interface now don' t go through WAN1 anymore. Is there something that you think I' ve being missed? I hope you can give me some useful advice! Thank you very much Francesco

    3 replies

    Dave_Hall
    Dave_Hall
    New Member
    April 2, 2014
    Doing this from memory as I' m not in front of a fgt, but check to make sure both distance and priority for the PPPoE settings on the WAN2 interface is set correctly and also check the routing monitor. I would also check for any firewall object/label to make sure none are referring to the old WAN2 address.
    BK_Bianko
    BK_BiankoAuthor
    Visitor III
    April 7, 2014
    Thank you, the problem was due to the distance " 5" that PPPoE connections are set by default when created. The other one was set to " 10" so it would had been woken up only with the failure of the wan2 link. By setting WAN1 to " 5" also the default route to the WAN1 showed up in the routing monitor and anything began to work fine again :). I have a " routing" question anyway.. Considering the configuration that I have posted in my first message and that: - WAN1 interface is linked to a LAN without NAT toward the internet, let' s say 45.222.111.112/29. WAN1 has IP 45.222.111.114. Gateway for this LAN is 45.222.111.113 and is an eth interface of my router Bintec. - WAN2 is the PPPoE with NAT Why, before I set the correct distance to WAN1, from the internet was I not able to communicate with the WAN1 interface? Was it perhaps due to the absence of the default route to the LAN 45..... through the WAN1 interface in the routing monitor? I thought that a packet would had " found" its way since it entered from the router interface. Perhaps it did not found a return path? Is it mandatory that a ECHO REPLY comes from the same IP address of the echo request? I hop you can clarify this doubts! :) Thank you very much
    Bunce
    Bunce
    New Member
    May 9, 2014
    If you configure both routers with the same distance, but different priorities, then both interfaces will respond, while allowing the route with lower priority to be the primary. If both (identical) routes have different distances, then the higher won' t appear in the active routing table, and will therefore not respond on that interface. At least, that how I understand it and have used this on our remote sites where we have dual WAN' s - one with PPPoE. (My lingo may be a bit off though..) You can actually override the Distance on the PPPoE tail (5) if you wish, but I think its only available in the cli. Cheers, Andrew
    ede_pfau
    SuperUser
    ede_pfau
    SuperUser
    May 9, 2014
    @Francesco When the distances were different, only the default route to WAN1 appeared in the Routing table of your FGT. So traffic coming in on WAN2 would be sent out on WAN1 which of course will not route correctly back to the origin. @Bunce You are right in everything but distance can be modified in the WebGUI (for ' normal' routes in the route setup, for PPPoE automatic routes in the Interface setup). Only the ' priority' parameter is CLI only. BTW, ' priority' is a Fortinet specific attribute. If you translate it with ' cost' you get it right when comparing routes with equal distances but different priorities.
    Terms & ConditionsAccessibility statement