Tomcat needs to be configured to allow for setup of cluster of two nodes over unicast. Following is section of my ${LIFERAY_HOME}/tomcat-6.0.32/conf/server.xml on server1 (replace node1 with node2 and swap location of IP_ADDRESSES and change unique_id to anything 16 bit long other than{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2}, on server.xml in server2) which allowed for this. IP_ADDRESSES here refer to private ip addresses of server1 and server2 respectively.
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<Engine name="Catalina" defaultHost="localhost" jvmRoute="node1">
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="6" channelStartOptions="3">
<Manager className="org.apache.catalina.ha.session.DeltaManager" expireSessionsOnShutdown="false" notifyListenersOnReplication="true" />
<Channel className="org.apache.catalina.tribes.group.GroupChannel">
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
autoBind="0" selectorTimeout="5000" maxThreads="6"
address="IP_ADDRESS_SERVER1" port="4444" />
<Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
<Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"
timeout="60000"
keepAliveTime="10"
keepAliveCount="0"
/>
</Sender>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpPingInterceptor" staticOnly="true"/>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.StaticMembershipInterceptor">
<Member className="org.apache.catalina.tribes.membership.StaticMember"
host="IP_ADDRESS_SERVER2"
port="4444"
uniqueId="{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2}"/>
</Interceptor>
</Channel>
<Valve className="org.apache.catalina.ha.tcp.ReplicationValve" filter="" />
<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
<ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener"/>
<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>
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