A diagram displays two Middle Tier Hosts, with their relevent components indicated. Host 1, the Original Host on the left is displayed with a Master Repository database containing Single Sign-On Schema and OID Schema. Above the databse, the SSO Server links to the Single Sign-On Schema, and to an OID Server box to its right. Above these are the DAS and DIP boxes. On the right side, Host 2, a New Host is shown, with all of the same components. A Replica Repository and the six components are shown in the same configuration as the Original Host. An arrow goes between the two hosts, from the OID Server box on the Original Host to the OID Server box on the New Host. This arrow is labeled 'LDAP-based Replication'. At the top of the diagram, a box indicates that Host 1 is the Middle-Tier Instance.