In reply to bathina.ravi:
You cannot set individual field variables - the sequence item variables are set through randomization. About the only thing you could do is extend TFB_Bfm_input_msg into another class that constrains src with the value you want, and do a factory override in your test to selected the extended item.
But it would be much easier to write your own sequence that sets the sequence_item variable by reading the config_db before finish_item() sends the sequence_item to the driver.
Also, both theovm_sequencer_util and ovm_update_sequence_lib_and_item macros have been removed from the UVM.