Multicast IP/port for session replication issue on VMWare Linux cluster

[Edmon Begoli]

I am really just getting into the area of session replication via multicast, so 
I need somebody's help here.

I am running a cluster of Tomcats on a virtual Linux RH ES3 cluster on VMWare. 
(host-only networking, static IPs)

My session replication is set with default settings:

              className="org.apache.catalina.cluster.mcast.McastService"
                mcastAddr="228.0.0.4"
                mcastPort="45564"
                mcastFrequency="500"
                mcastDropTime="3000"

It fails miserably even on the startup. It can't even create the device socket. 

Is there anything I need to configure respective to my cluster's sub-net or 
anything related to DHCP to make this work.

Any help is greatly appreciated.

Thank you,
Edmon