The JGroups subsystem supports any JGroups protocol, including TUNNEL.
If you're referring to the org.jboss.as.clustering.jgroups.subsystem.Protocol enum, please disregard this - it is not actually used and will be removed in the next release.
Sorry for the confusion.
Excellect - I'll give it a go.
You're right though - I was looking at the enums and was confused as I couldn't see where they got used.