A cross-subnetwork search is designed to find an LU outside the local APPN subnetwork. Because other APPN searches are sent between nodes that are in the same APPN subnetwork, this search type is employed at border nodes to forward searches for a requested LU to other APPN subnetworks. The target nodes of a cross-subnetwork search may be found in the directory services database, monitored dynamically, or explicitly defined by definition statements.