I have been able to fix the problems that I was having and I seem to have installed ns propely. however, when I run ./ns test-suite.tcl tahoe1, it gives an error. The error is as follows ./ns test-suite.tcl tahoe1 ld.so.1: ./ns: fatal: libotcl.so: can't open file: errno=2 Killed Any ideas about that. Shahzad Ali.