I already read previous threads on openfire clustering.
So, you have probably read that clustering is not available anymore? Enterpise version is gone, so the clustering is gone too. Clustering was based on the commercial closed source code. Openfire was made fully open source, but clustering cant be open sourced, so it is not available anymore. Unless you are a legal Enterprise version owner. Then you should contact JiveSoftware. On this site noone can answer clustering question. Some folks are doing some work on the open sourced clustering solution, but it is still in pre-alpha stage i think.