Setup replication between two Galera nodes I've been using MariaDB 10.2 Galera with 3 nodes successfully on local servers. Now, I have a second 3-nodes Galera cluster on another location, joined by an Site-to-Site IPSec Tunnel.

I can't really merge it to one big cluster, as the performance drawback would be high (due to physical positions of those two datacenters).

I'd like to setup asynchronous replication between those two clusters but I can't make it two work. Using "old-school" master-master replication (which is master/slave in both ways, as I get it) between two nodes doesn't work as conflicts starts to rise.

Is there a way to setup asynchronous replication between those two Galera clusters ?

Thanks for your help.
If you have any AUTO_INCREMENTs, I think it is impossible.

You are effectively asking for 6 Masters talking to each other.  For AUTO_INCREMENT not to mess up, you need auto_increment_increment = 6.  But Galera will insist on using 3, since there are only 3 "nodes" in [each] "cluster".