Hello NS users, well, I created a LAN as follows : set LAN [$ns newLan $nodelist $opt(bw) $opt(delay) \ -llType LL -ifqType Queue\DropTail -macType Mac/802_3 -chanType Channel] and I can't find how to track dropped packets (tcp) due to a collision. If anyone experienced that, his help would be appreciated. Have a nice day Hanus Joel, Belgian student