Both the Replication Agent for UDB and ECDA Option for ODBC must use IBM DB2 Universal Database client libraries. Cataloging configures an IBM DB2 Universal Database client so that it knows how to connect to a particular database. Cataloging also creates a database alias, which Replication Agent or ECDA uses as the data source name.
By default, the client libraries are installed along with the IBM DB2 Universal Database server. You can also separately install an IBM DB2 Universal Database client on a host other than the one on which the server is installed. In either case, you must perform cataloging in the IBM DB2 Universal Database client that Replication Agent or ECDA is using. If Replication Agent and ECDA are installed on different hosts, they are using different IBM DB2 Universal Database clients, so the cataloging must be performed in both of the clients.
If the client and the server are on the same host, and there is only one IBM DB2 Universal Database server running, cataloging may have been performed when the IBM DB2 Universal Database instance was installed and the databases configured. If so, no additional cataloging is required.