UCS Manager monitors all of the elements (servers, CPU's, DIMM's, IO Modules, Chassis's, Fabric Interconnects, etc) for both the health and configuration of the hardware.  It federates all of the state, inventory, faults, and configuration into UCS Manager.  UCS manager's scope of control and monitoring includes all the aforementioned hardware, but does not include the Host OS or hypervisor / apps running on it.  When sending out SNMP traps, UCS Manager just converts the fault conditions it stores in the XML Database (the faults you see in the UCS Manager GUI) into a SNMP trap and sends the fault condition on behalf of the failed component (server, CPU's, DIMM's, IO Modules, Chassis's, etc).  UCS Manager utilizes either of the SNMP daemons running on the fabric interconnects to send the details.  That is why the IP you get in your NMS system is either of the fabric interconnect IP's, and not the HOST IP, as UCSM doesn't have details about the host running on the  system.  I would recommend you look at the UCS Manager MIB Reference Guide for more details:

http://www.cisco.com/en/US/docs/unified_computing/ucs/sw/mib/b-series/b_UCS_MIBRef.pdf

Thanks,

Eric