We know that ARP request needs src and dst MAC & IP address to find other devices on network
Someone here has a nice quote or Mark Twain in their automatic signature: “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so. “
The answer is quite simple, if you send a frame with some MAC address as a destination one over an L2-transparent network, a device with that MAC address will accept it no matter what ethertype and higher protocol layers that frame contains, and no matter what IP address the receiving device has. So to communicate
, it is enough for two devices on an L2 segment to know each other's MAC addresses, and support the same protocol for which MAC addresses are sufficient.
The other issue is how to discover
the MAC address of the other device if you cannot read it on the label on the device; the tool here are various neighbor discovery protocols (the standard LLDP and the proprietary ones like C(isco)DP and M(ikrotik)NDP), which use multicast or even broadcast MAC addresses to get accepted by any device on the L2-transparent network. This is the same method which ARP uses - ARP sends the actual request to a broadcast MAC address too. The discovery protocols just carry another type of information than ARP: whereas ARP is used to translate a known IP address to a corresponding MAC address, the name "discovery" is slightly misleading, as the devices actually use these protocols to advertise
various bits of information about themselves to all adjacent devices that support that particular discovery protocol, like their MAC address, vendor name, software version, IP address used for management, supported networking features etc. And the discovery protocols do not care much about the IP settings of the interface they run at (as they don't need any IP address for their own operation). Every Mikrotik device sends MNDP frames from all interfaces where this functionality is permitted, regardless their IP configuration. See https://wiki.mikrotik.com/wiki/Manual:I ... _discovery
for details. Winbox listens to MNDP and builds the neighbor list based on MNDP packets received - if you disable neighbor discovery on the Mikrotik interface to which your PC is connected, Winbox will stop listing that device among neighbors, but it will still be able to connect if you enter the device's MAC address manually.