[ns] -DDEBUG option

[Farhan Hyder]

 Hello all,

I can't figure out what does it mean to 'compile NS with -DDEBUG option'.
Can anyone help me with it ? I mean the procedure, how exactly do we do it ?

"Note: ns must be compiled with -DDEBUG for this option to
          work. Also, if debug_ (the standard debug flag) is set to 1, then
          all the bits in debugMask_ are set."


Thanks,
Farhan Hyder