When IP Multicast is not available the mcastproxy program can be used to
connect hosts. Suppose that students from four different campi want to use
TGWB. Suppose also that multicast is available in the local networks but it is
not available among the campi. In that scenario, the mcastproxy program
can be used to connect each campi. As shown in Figure
, there is one instance of mcastproxy in each
campus. Each mcastproxy instance can listen to local multicast traffic
and send it unicast to each other campus. The packets received through unicast
are sent through multicast to local users.
mcastproxy program uses a configuration file, mcastproxy.conf from the .tgwb directory located at user's home. Next is presented an example of this file.
#Multicast group address GROUPADDR=225.1.2.3 #Number of hosts to send unicast packets NADDR=2 #IP Addresses list to send unicast packtes ADDRLIST 192.168.1.2 10.0.0.1 # Time to live for multicast packets TTL=1 REUSEADDR=0 # Loopback: 1 enable, 0 disable LOOPBACK=1 # Unicast port to use UCASTPORT=32566 # Multicast port to use MCASTPORT=5151