Multicast "Proxy"

This is application should be used to build a "unicast bridge" between 2 or more
multicast groups.

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Using mcastproxy
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For instance, suppose one want to run a multicast session in 2 networks A and B.
A and B have local multicast support but there is no such support between them.

So, we can simulate this support using mcastproxy following the steps below:

1. Choose a machine in network A, e.g., m1.A
2. Choose a machine in network B, e.g., m1.B
3. Before starting run mcastproxy in m1.A you must fill the mcastproxy.conf file
   with the options (See "The mcastproxy Config File Options" section below):

        GROUPADDR=225.1.2.3
        NADDR=1
        ADDRLIST
        m1.B
        TTL=1
        REUSEADDR=1
        LOOPBACK=0
        UCASTPORT=32566
        MCASTPORT=5151
        
4. In m1.B the mcastproxy.conf file should be like:

        GROUPADDR=225.1.2.3
        NADDR=1
        ADDRLIST
        m1.A
        TTL=1
        REUSEADDR=1
        LOOPBACK=0
        UCASTPORT=32566
        MCASTPORT=5151

5. When both mcastproxies are running, you can use any Reliable Multicast 
   Library based application through A and B.
   
---------------------------------- 
The mcastproxy Config File Options
----------------------------------

    GROUPADDR
        The IP multicast group address
    NADDR
        Number of proxies addresses to send data to
    ADDRLIST
        After this it will be the address list of other proxies you will send 
        data to  (one per line)
    TTL
        Time to Live for the multicast packets
    REUSEADDR
        Enable address reuse
    LOOPBACK
        Enable loopback.
        Values:
            0 - loopback disabled. You MUST NOT run a multicast client in the
                same host which you are running mcastproxy
            1 - loopback enabled. This will work only for special packets such
                as the ones from Reliable Multicast Library
    UCASTPORT
        Unicast port where you will listen to. This will be the same port
        to where you have to send packets to
    MCASTPORT
        Multicast port where you will listen and send packets to


