Outbound mapping allows you to translate an AuthID and passwords before a request is sent to a remote XDB Server. A request can be sent that either references a remote location controlled by another XDB Server (using a three-part name) or the remote XDB Server itself (using CONNECT). The values in the system catalog table SYSIBM.SYSLUNAMES indicate that requests going to the remote XDB Server should be translated. Based on the values in SYSIBM.SYSUSERNAMES, the AuthID is mapped and the request is sent to the remote server as if it came from the newly mapped AuthID.
Mapping AuthIDs before they leave an XDB Server can be useful when a particular remote XDB Server is configured to accept requests from only one or two AuthIDs. This allows you to translate all AuthIDs going to that XDB Server into valid AuthIDs for a remote XDB Server. Outbound mapping can also be used to eliminate duplicate AuthIDs at different XDB Servers. Any potential duplicate AuthID (or all AuthIDs) can be mapped to different AuthIDs before requests are sent to remote XDB Servers.
While remote XDB Servers can be configured to allow all users access from your XDB Server, outbound mapping keeps the administration tasks on one XDB Server. In a distributed environment with many XDB Servers, it can quickly become confusing to have to track the current valid AuthIDs for all other XDB Servers in order to maintain your own system tables. Outbound mapping allows you to control how queries appear when leaving a particular XDB Server.