can somebody tell me what is the difference between the following example of ns. ex1: set mac [new Mac/Csma/Cd] set ifq [new Queue/DropTail] $mac target $ifq ^^^^^^^^^^^^^^^^^ ex2: set mac [new Mac/Csma/Cd] set ifq [new Queue/DropTail] $ifq target $mac ^^^^^^^^^^^^^^^^^ Thanks, Zh-Ming Lii