There are 2 layers of communication
For inband communication and statistics UFM sends standard MADs and receives specific InfiniBand traps in return.
For management purposes, Mellanox switches have an embedded UFM agent.The UFM Server sends a multicast notification to MCast address 188.8.131.52, port 6306. The switch management replies to UFM (via port 6306) with a unicast message that contains relevant information about the switch (IP,GUID,Firmware etc...)
Afterwards the information is being exchanged via XML