[ns] exponential traffic generator for TCP

[amrutha ravichandran]

Hi,
I want to use exponential traffic generator for TCP..
is it possible??
for example:

set e [new Application/Traffic/Exponential]

$e attach-agent $tcp1

but when i do this im getting an error saying

"null-invalid packet type(exp)"

what does this mean??Pls help..its urgent

Thanks,

Amrutha.