How does one monitor failover ospf links???

RouterOS The Dude
1

Tower 1 has a 2.4 Omni and also a 5GHz link to tower 2; tower 2 has another 5GHz link to tower 3. And tower 3 is a 2.4 client of tower 1 as a failover link. I know this isnt the best way, but it does work if the link between tower 1 and tower 2 fails. These routes are included in the same ospf domain: I have the latest version of the dude, my question is how does one monitor if the failover happens.

Lets say the the link between tower 1 and tower 2 fails, the 2.4 link between tower 1 and tower 3 starts routing traffic. How does one get alerted that the 2.4 link has started and the 5GHz link has quit in the dude?

2

There are at least 2 ways to monitor such a link

  1. If your device can send syslog messages when route changes you can use dude syslog server and alert when such a message received.
  2. You can check the routing table at the devices.
    In normal situation the next hope for route will be one, if the main link will go down the next hope will change
    Suppose you have such a routing table on device 1
    10.0.0.0/24 10.0.1.2
    10.1.0.0/24 10.0.1.2
    10.2.0.0/16 10.0.1.2
    0.0.0.0/0 10.200.1.2
    When the main link goes down whe routing table will change and will be
    10.0.0.0/24 10.0.2.2
    10.1.0.0/24 10.0.1.2
    10.2.0.0/16 10.0.1.2
    0.0.0.0/0 10.200.1.2
    To make dude to notify you when the route changed you have to make a function which will check the presence of the IP 10.0.2.2 as a next hope for 10.0.0.0 prefix in routing table.
    to do it you have to create the function that checks IpRouteNextHope - 1.3.6.1.2.1.4.21.1.7
    the function will look like
<?xml version="1.0" ?> 57 1538516 Route_check string_find("10.0.1.2",oid("1.3.6.1.2.1.4.21.1.7.10.0.0.0")) The function will return 0 in normal situation and other value if the route will change. And now you can make probe, which will check Route_check() function and notify you if it returns not 0

Please let us know how reliable it works, if checked it on lab, because do not need such a probe in real life :slight_smile:

3

Thank for the reply, sounds feasable. I am wanting to try it in a lab environment first, but would ideally like to use it on our physical network, that is how it is setup for now. If I am able to complete this, I will post the results. If it takes a long time to set up the lab, I can email later, thanks for the help. Josh