The MikroTik script to detect whether the interface is really working

На русском

Advantages:

• Can be used for one or more interfaces.
• Any type of interface.
• Ping multiple hosts, since relying on a single host is too unreliable.
• You can run it as often as you like — it can detect fail relatively fast.
• Easy setup — you only need to set a couple of variables.
• Works on RouterOS 6 and 7.

Setup

Just create script in /system scripts and set variables in SETTINGS to your liking. Variables are provided with comments and examples.

Add a task to the scheduler with short interval (even a couple of seconds is OK).

/system script run Check_ISP1

You can use this firewall rule to test the script:

/ip firewall filter add action=drop chain=output comment=INT_CHECK_TEST \
    out-interface=ETHER1 protocol=icmp