In reply to chr_sue:
Indeed, I created agent for that protcol in which i created its interface, drv, mtr, seqr. Imade this agent interface paramterizable. then in env i intantiated three agent from the agent i created. But the issue is when i want to assert a sig of a specific interface among these three interfaces it gets asserted for all interface. Note that, the assertion of that signal is done in run phase inside a block of fork join with protcol process.