We are considering using Cross Data Center Replication between SolrClouds in different domains which have a firewall between them. Is it documented anywhere how many firewall holes will be needed? From each source SolrCloud node to each target SolrCloud node? From each target SolrCloud node to each source SolrCloud node? From each source SolrCloud node to each target Zookeeper node? Do the target SolrCloud nodes ever need to talk to the source Zookeeper nodes (or vice versa)? Is there a need for communication between the two Zookeeper clusters?
Thanks