Hello, I need help about usage of "advanceby". I have written a code like set tcp [new Agent/TCP] set sink [new Agent/TCPSink] $ns attach-agent $n0 $tcp $ns attach-agent $n3 $sink $ns connect $tcp $sink $tcp advanceby 100 and it gives me error. Topology is n0-------n1-----n2-----n3 Any ideas, pointers will be appreciated. Selma Yilmaz