sender_win.stop();
break;
case Event.CONNECT:
Object ret=down_prot.down(evt);
sender_win=new AckMcastSenderWindow(this, new StaticInterval(timeout));
// send join announcement
Message join_msg=new Message();
join_msg.putHeader(this.id, new SmackHeader(SmackHeader.JOIN_ANNOUNCEMENT, -1));
down_prot.down(new Event(Event.MSG, join_msg));