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GRE between two RouterOS devices

Sun May 14, 2023 8:46 pm

Hi,
I have a number of GRE tunnels between various locations (all using RouterOS devices). With ROS v6 it all worked as expected. After replacing one of the routers with a newer device running ROS v7.8, the GRE tunnel to a ROS v6 device didn't come up. After some Googling, I disabled GRE keepalive on the v7 side and got the tunnel up and running again. There's one downside though: when a remote end of a GRE tunnel is not reachable, the status of the local GRE interface changes up and down every second. So my log gets flooded with a 'link up' - 'link down' messages pretty quickly.

The GRE setup I use is pretty simple:
Every pair of GRE endpoints is located in its own /30 subnet: i.e. router#1 has 192.168.100.1/30 and router#2 has 192.168.100.2/30.
As soon as I create a GRE interface (with keepalive disabled) and assign an IP address to it, it starts to go up and down every second.

While Googling for GRE and RouterOS, I saw several recommendations to disable GRE keepalive (due to particular implementation in ROS being Mikrotik-specific). But then noone mentioned the interface will flip up and down every second when the other end is not reachable...
Did I miss something? Should I configure GRE in some other way to get it 'permanently down' when the other end is unreachable?

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