A Directory Server that replicates to other servers is called a supplier. A Directory Server that is updated by other servers is called a consumer. The supplier replays all updates on the consumer through specially designed LDAP v3 extended operations. In terms of performance, a supplier is therefore likely to be a demanding client application for the consumer.
A server can be both a supplier and a consumer, as in the following situations:
In multi-master replication, a master replica is mastered on two different Directory Servers. Each server acts as a supplier and a consumer of the other server.
When the server contains a hub replica, the server receives updates from a supplier and replicates the changes to consumers.
A server that plays the role of a consumer only is called a dedicated consumer.
For a master replica, the server must do the following:
Respond to update requests from directory clients
Maintain historical information and a change log
Initiate replication to consumers
The server that contains the master replica is responsible for recording any changes made to the master replica and for replicating these changes to consumers.
For a hub replica, the server must do the following:
Respond to read requests
Refer update requests to the servers that contain a master replica
Maintain historical information and a change log
Initiate replication to consumers
For a consumer replica, the server must do the following:
Respond to read requests
Maintain historical information
Refer update requests to the servers that contain a master replica