In a fully meshed multi-master topology, each master is connected to each of the other masters. A fully meshed topology provides high availability and guaranteed data integrity. The following figure shows a fully meshed, four-way, multi-master replication topology with some consumers.
In Figure 11–2, the suffix is held on four masters to ensure that it is always available for modification requests. Each master maintains its own change log. When one of the masters processes a modification request from a client, it records the operation in its change log. The master then sends the replication update to the other masters, and in turn to the other consumers. Each master also stores a Replication Manager entry used to authenticate the other masters when they bind to send replication updates.
Each consumer stores one or more entries that correspond to the Replication Manager entries. The consumers use the entries to authenticate the masters when they bind to send replication updates. It is possible for each consumer to have just one Replication Manager entry that enables all masters to use the same Replication Manager entry for authentication. By default, the consumers have referrals set up for all masters in the topology. When consumers receive modification requests from the clients, they send the referrals to back to the client. For more information about referrals, see Referrals and Replication in Oracle Fusion Middleware Reference for Oracle Directory Server Enterprise Edition.
Figure 11–3 presents a detailed view of the replication agreements, change logs, and Replication Manager entries that must be set up on Master A.Figure 11–4 provides the same detailed view for Consumer E.
Master A requires the following:
A master replica
A change log
Replication Manager entries for Masters B, C, and D, unless you use the same Replication Manager entry on each replica
Replication agreements for Masters B, C, and D, and for Consumers E, and F
Consumer E requires the following:
A consumer replica
Replication Manager entries to authenticate Masters A, and B when they bind to send replication updates