Hello. I really know what you're going through since I have the same problem myself. =(
I have almost gotten session replication to work, but only in windows. I setup JBoss as 2 local instaces and let it run on 2 different ports on the same windows machine and it works with a small testprogram called ClusterTest.war. However with a bigger application it doesn't work, you get logged out when one of the nodes is taken down.
Now my question... how did you get Clustering to work in Linux? I have 2 linux machines and they insist on not finding each other. However, if I bring (computer nr 3) my windows machine up, all the machines find each other, but not just the two linux machines alone. Really strange. What did I miss in my Linux installation?
I have disabled firewalls.
I have added routes with this command: "route add -net 18.104.22.168 netmask 240.0.0.0 dev eth0".
You can browse and dl files from both ofthem. No problems there.
The version is Mandrake 9.1. They are using JBoss 3.2.1. Java version is j2sdk1.4.1_03.
I've done some additional testing with a JavaGroups demo program and ethereal. And the problem seems to be that the linux computers can send multicast packets without problems, but they can _not_ recieve them.
Any ideas why this hapens? And how do I cure my computers?
Finally I have found the roots of the evil lurking in my system. The villain was an innocent looking little flag called allmulti. To get my JBoss instaces to see each other in linux I issued the following command:
# ifconfig eth0 allmulti
Then they found each other. Don't be fooled by the MULTICAST flag in the ifconfig output. If it doesn't work just enter the line above and ifconfig should show:
UP BROADCAST RUNNING ALLMULTI MULTICAST
Ohh, I'm so happy! This will be celebrated with a coffee.