Hello, I’ve met some insistency with wiki(official docs) and practice.
ROSv6 →
Protocol OSPF, Instance setting - while using default Router-ID - is a maximum IP address on router, by the practice it’s different.
It’s also spotted in MTCRE questions.
By the practice mostly using is LOWEST IP address.
I prefer to always specify a loopback address so there are no surprises [emoji41]
Depends on what you consider to be “lowest IP”, we already once changed documentation because somebody stated that manual is wrong.
You should always use a loopback IP as the router ID.
Other vendors’ routers will use loopback interface addresses (and choose the highest IP in Cisco’s case) before they use interface addresses.
In Mikrotik’s case, there’s no such thing as a true loopback interface. We generally make a bridge interface, name it “loop” or “loopback” or something like that as a way to know what its purpose is, and use that as a surrogate loopback interface. The difference is that this is no different to the Mikrotik from any other bridge interface, so Mikrotik’s going to choose the (apparently) lowest IP on the system.
In Mikrotik, it’s good practice to specify the router ID explicitly in OSPF, BGP, MPLS, etc, and to use a loop IP for this.
+1 for setting a router-id.
Can’t even begin to describe all the bad things I’ve seen happen because the router-id wasn’t set. The most common is a duplicate router-id of 192.168.88.1 on each MikroTik router 