Using multicasting can be an issue in the network. Multicast is based on UDP and is often blocked in the network. I encountered this issue at a few customers. The solution is rather simple, instead of using UDP/multicast we use TCP to point to the nodes in the cluster.
In the next example, we have two nodes; node1 and node2. They will use port 7900 with a range of 3 to broadcast the BPEL process changes.
On each node:
cd /u01/appl/p1bplpe/product/OracleAS_1/bpel/system/config
mv jgroups-protocol.xml jgroups-protocol.xml.old
cat >> jgroups-protocol.xml << EOF
<config>
<TCP start_port="7900" loopback="true"
send_buf_size="32000" recv_buf_size="64000"/>
<TCPPING timeout="3000" initial_hosts="node1[7900],node2[7900]" port_range="3" num_initial_members="3"/>
<FD timeout="2000" max_tries="4"/>
<VERIFY_SUSPECT timeout="1500" down_thread="false" up_thread="false"/>
<pbcast.NAKACK gc_lag="100" retransmit_timeout="600,1200,2400,4800"/>
<pbcast.STABLE stability_delay="1000" desired_avg_gossip="20000"
down_thread="false" max_bytes="0" up_thread="false"/>
<VIEW_SYNC avg_send_interval="60000" down_thread="false" up_thread="false" />
<pbcast.GMS print_local_addr="true" join_timeout="5000"
join_retry_timeout="2000" shun="true"/>
</config> EOF
cp jgroups-protocol.xml jgroups-protocol.xml.new
Restart the nodes

