[ns] ask you some question about error model

[wanxiujin]

 
 

hello:
   now may I ask you some question about NS error model?
   I have seen a text on ns forum about the error model:
  
     set errObj [new ErrorModel]
     $errObj unit bit
     $errObj FECstrength 1
      $errObj datapktsize 1000
     $errObj cntrlpktsize 80
     $errObj drop-target [new Agent/Null]
 
I do the NS recently,but I don`t know the datapktsize cntrlpktsize and 
FECstrength meaning, can you tell me the usage?
  
thank you very much!