[ns] TCP ACKs - change route

[Tatiana Polishchuk]

I remember I saw related question in the list, but without answer.
I'm trying to send the ACKs for the TCP packets using specific routes. In
the tcp-sink.cc module there is a function ack() which sends ACK packets
using send(P, 0)  method. Does anybody know where the function is defined
and there the destination for the packed is specified? Please, help.