I'd suggest you take a look at JBoss 4.2 Clustering Guide whether you got the UDP route or the TCP route - also, I dont know how involved a network setup you have with switches and routers - but our IP engineering team had to setup UDP multicast IP's and ports when we did JBoss EAP 6 clusters
From the guide, and with regards to TCP
Alternatively, a JGroups-based cluster can also work over TCP connections. Compared with UDP, TCP generates more network traffic when the cluster size increases. TCP is fundamentally a unicast protocol. To send multicast messages, JGroups uses multiple TCP unicasts. To use TCP as a transport protocol, you should define a TCP element in the JGroups Config element. Here is an example of the TCP element.
<TCP start_port="7800"
bind_addr="192.168.5.1"
loopback="true"
down_thread="false" up_thread="false"/>`
Theres a lot more information on the page - and if you click one page back, its the UDP setup
UDP is the preferred protocol for JGroups. UDP uses multicast or multiple unicasts to send and receive messages. If you choose UDP as the transport protocol for your cluster service, you need to configure it in the UDP sub-element in the JGroups Config element. Here is an example.
<UDP mcast_addr="${jboss.partition.udpGroup:228.1.2.3}"
mcast_port="${jboss.hapartition.mcast_port:45566}"
tos="8"
ucast_recv_buf_size="20000000"
ucast_send_buf_size="640000"
mcast_recv_buf_size="25000000"
mcast_send_buf_size="640000"
loopback="false"
discard_incompatible_packets="true"
enable_bundling="false"
max_bundle_size="64000"
max_bundle_timeout="30"
use_incoming_packet_handler="true"
use_outgoing_packet_handler="false"
ip_ttl="${jgroups.udp.ip_ttl:2}"
down_thread="false" up_thread="false"/>`
The next 20 pages of clicks or so go into all the different types of setups you can use!
Update I also just found the better pdf version of the documentation!