A cross-connect for interfacing high-speed ports and having add/drop multiplexing capabilities for permitting simultaneous access to all individual subscribers may be improved by utilizing a switch block arrangement for allowing downstream subscribers to be switched among each other without the need to be switched upstream through the cross-connect or may alternatively be improved by substituting an expansion shelf in place of a line shelf so as to permit the addition of additional line shelves and hence, additional subscribers. This latter improvement is made possible by assuming that not all subscribers will need access to the cross-connect at the same time. A switch block for such arrangements can output either an input data signal previously stored in a switch memory or a daisy-chain input that is output from another switch block in the arrangement.