you are right. it works as is when I disable the interface of the LTE. It continues seamlessly. And re-enabling it works also great.
So when the physical connection has a problem I should be fine.
I wonder though what happens if the internet provider LTE connection is there but access to internet is not working.
Will it failover?
No, that's what "recursive routing" would add: a check that
something (e.g. google dns typically) is "pingable" before enabling a route. But as you found out, it's make the config awfully complex for what I think is a rare corner case (e.g. LTE is running and there NO internet). More typical is you have a connection and internet is SLOW, and "recursive routing" still keep using LTE since ping still works.
My advice is see if you run into a case of the LTE being running before going down recursive routing. It totally works, but it's a steep learning curve to setup.
Other approaches include
Netwatch
If you need a "ping test" for LTE, the other approach is to use "
netwatch" with a script. Since netwatch also does a continuous ping, you can use this approach to do whatever you'd like upon success or failed ping. For example, the old docs show how to send email using netwatch for an outage:
https://wiki.mikrotik.com/wiki/Manual:Tools/Netwatch. You make this more complex too so if ping fails, a more complex script can try to disable/re-enable LTE interface as an attempt to "fix it", and/or a bunch of other home-grown approaches that use "netwatch" if you search this forum.
Detect Internet
The flip side of "netwatch" and "recursive routing" is "
detect internet". However, this doesn't help that much since it doesn't adjust routes, nor disable LTE if there is no internet on it. Maybe eventually this will be expanded by Mikrotik, but not much help here. Now it can be combine with netwatch since it know which interfaces have internet and which don't. But like I said it doesn't do much on it's own, other than report if the internet is up somewhere.
Traffic Monitor
There is another family of load balancing / failover that uses scripts with traffic monitor. This is pretty complex. And this approach isn't per se monitoring "up" or "down", rather "high" or "low" amount of traffic. So typically it's use in combination with the other approaches above. But that's what helps cover case that you need "fail over" because of HIGH load on the LTE. See this older MUM presentation:
https://mum.mikrotik.com/presentations/US12/tomas.pdf – not sure how well it work in V7 but more to give you the full picture of options.
Default Route Distance
As previously described, change the default route distance for either an LTE interface, DHCP Client, or directly in a static IP Route. This doesn't validate the internet is "up", but if the interface is "down", RouterOS won't use the route on a inactive/disabled/"un-plugged" interface.
Mikrotik's Recursive Routing
See
https://help.mikrotik.com/docs/pages/vi ... d=26476608