[ns] Multicast Error

[Sencun Zhu <szhu1@ise.gmu.edu>]

Hi,all, in current version of ns, the address includes a port, I wonder
when we need to set its value. My code runs okay in ns2.1b3 where the
address is just nsaddr_t(no port), however, when I use multicast DM ,  now
the error is from file classifier-mcast.cc method 
classify(packet  *pkt):
....
 tcl.evalf("%s new-group %ld %ld %d cache-miss", 
                                  name(), src, dst, iface);
....

the below is the error:

ns: �o190 new-group 36 -2147483648 -1 cache-miss: invalid command name
"\314o190" 
while executing
"\314o190 new-group 36 -2147483648 -1 cache-miss"


here we can find iface=-1, which will make ns exit. 
According to ns manual chapter 22:multicast routing, I have already used:
....
$udp set dst_addr_ $group
$udp set dst_port_ 0 ( why is 0?) 



any hints will be appreciated.

Sencun