This FAQ show how to config MCAST on both of Avalanche client side and server side.
On client side:
5000 MCAST://184.108.40.206 #means joining, keep 5000ms, then leaving
MCAST://220.127.116.11 DATA=100 #means joining, receive 100 packet, then leaving
MCAST://18.104.22.168 DATA=100 LINGER=1000 #means joining, receive 100 packet, leaving, waiting for 1000ms then join the next
On server side:
1) Select the MCAST server type and port
2) Input the first group address and he increment
3) Select the way and media type
4) The number of server association IP address will control the total groups.