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OSPF Failover with Static Route

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  • OSPF Failover with Static Route

    First of all, I apologise for the lengthy description, but there is no way that I can accurately describe my problem in 2 sentences . Currently, i have a problem with a failover solution using OSPF with a backup static route. I have added a diagram in attachment.The preferred link is a wireless link between 2 sites using non-cisco equipment. The VPN Firewall's are also non-cisco and we cannot make changes to the configuration.I have considered a scenario with 2 static routes (with the backup a higher metric), but since the cisco routers have no idea when the wireless link goes down, i have selected OSPF to be running between R1(870 Main office) and R2(870 Remote Network).

    To test the failover I perform a shutdown on the e1 interface on R1. OSPF detects this, and installs the static route to the remote network through firewall 1 as it is supposed to. On the other end, the same thing occurs. After reactivating the interface the wireless link OSPF route is reinstated into the routing table, so imho everything works as it should.

    Yet we encounter the following problem. For test purposes, i am using a client on the main network to perform constant pings to both a host on the remote network, and the R2 e0 interface during the above described shutdown & reactivation of the interface.
    We see that the ping to R2 works perfectly:
    • Goes down after the shutdown
    • After a couple of seconds, uses the failover VPN Tunnel
    • After reactivation, uses the wireless link again
    However, the ping to the remote host (ESX machine) goes down, then goes to the backup interface, and then just stops working (timeout). I am pretty sure that my routing solution works well, but am I missing something here? ARP problems? Can anyone shed any light on this for me? Only 1 VLAN is in use, and OSPF is configered correctly (area 0) on both routers with both interfaces included in the routing process. The network between the 2 routers has another ip range (f.e.

    Thanks a lot
    Attached Files

  • #2
    Re: OSPF Failover with Static Route

    Shot in the dark but, can you confirm ping is actually allowed through the firewalls on the backup route?


    • #3
      Re: OSPF Failover with Static Route

      ICMP messages are allowed (all traffic is allowed through the firewalls as far as these networks are concerned)

      When the backup route through VPN takes over the pings keep going (we see a drop in response time, and a traceroute shows that pings are going over the correct line). The problem occurs when the primary route is reinstated.