Verifying a multicast cluster

I'm trying to verify that my multicast cluster is working properly: clients
on any node should receive msgs sent to any other node.

Using 5.10, on Ubuntu

In the past I have successfully created a network of brokers using a static
list of urls. I could then run a "subscriber" client that connected to host
1 via a tcp://host1:11111 url and a "publisher" that published a message to
host 2 via a tcp://host2:2222 url. The subscriber would, of course, receive
the message even though it was listening on a different host in the cluster.
That's the whole point of the cluster so yay for activemq!

Now I am trying to do the same with a cluster configured via multicast and
it is not working. I use those same tcp:// urls on the two clients as shown
above and each successfully connects, however the message is not received by
the subscriber program.

http://activemq.apache.org/networks-of-brokers.htm
<http://activemq.apache.org/networks-of-brokers.htm>

I plan to use "discovery:(multicast://default)" urls in my final production
client configuration. However, when I do that in my test programs they both
connect to the same physical node in the cluster which renders my test
inconclusive. That is what lad me to try the tcp:// urls.

Is it invalid to use tcp:// urls in the clients to connect to a multicast
cluster perhaps?

Here is a node's config file.... I hope this raw tag works as I expect! :)

Thanks!
John