hello I am new about NS question 1 : Recently , I want to add a new object in Ns is it enough?? (1)build a new object in c++ (2)use a new object inTCL ./TCL/Lib (3)make question 2 how to drop packet in 'DelayLink' Object? question 3 if I want to add selective repeat machine (link layer) how can I do first thanks a lot