[ns] Calculate err rate: track lost packets

[S.Nasir@surrey.ac.uk]

Hi,

Can some one please guide me how can we keep track of which packets are drops and how many were the total number of packets in one of the communication links. 
 
Need this information for formulating an error model for a certain type of traffic under certain network conditions over the WLAN.
 
Looking forward to hear some helping advice
 
Regards
Sabih