New in current RouterOS v6.xx is a quick way to test cables plugged into Ethernet ports on your device. It’s a little odd how it works, but it can show you cable length, open pairs, and cable distance to where the problem is.
From a Terminal, to test ether3 you would enter:
/interface ethernet cable-test ether3
Oddly enough, it appears to only work if there IS a problem. If you have a link on that port, it will return a “status: link-ok” and then just hang until you hit “Q” to quit. It appears to be sitting there waiting for a change in status, which isn’t going to happen on a good link.
I just tried with an unused port on an RB2011 and this is what it returns:
name: ether4 status: no-link cable-pairs: open:0,open:0,open:0,open:0 -- [Q quit|D dump|C-z pause]
While it was sitting there I plugged in a 1M cable and let it hang. Once the readings stabilized, it changed to:
name: ether4 status: no-link cable-pairs: open:1,open:1,open:1,open:1 -- [Q quit|D dump|C-z pause]
Interesting little feature they added there. Only works on certain models, most notably the RB750, RB2011, and Cloud Core series.