The Directory Server's replication mechanism relies on the server's location information to reduce protocol traffic on WAN links.
During protocol negotiation, the replication server with the highest WAN Gateway priority (priority 1 indicates the highest priority) automatically assumes the role as the WAN Gateway Server for that particular location. The Gateway Server’s main function is to route update messages from other non-gateway servers at the same location to remote WAN Gateway servers at other locations. At the destination point, the replication server with the WAN Gateway role receives update messages from other WAN gateway servers at other locations and pushes them out to all replication servers at the current location.
This setup ensures that all WAN communication flows through the WAN Gateway Servers.
If the WAN Gateway Server is temporarily unavailable due to planned or unplanned downtime, the system dynamically re-routes updates to a newly-designated WAN Gateway Server in the same location. The replication server with the next highest WAN Gateway priority number automatically assumes the WAN Gateway role. For deployments with entry-balancing Directory Proxy Servers, there is one WAN Gateway Server per data set.
By default, all servers are enabled to serve as WAN Gateways and all are set to priority 5, which makes them all equal. After replication has been enabled, you can change the WAN Gateway priority using dsconfig.