A datacommunication interconnection system includes (a) an extension trunk cable-connector assembly and (b) a trunk cable-connector assembly. The extension trunk cable-connector assembly comprises: a first cable including a plurality of first subunits, each of the first subunits comprising a plurality of twisted pairs of conductors; a jack attached to one end of the cable; and a plug attached to an opposite end of the cable. Each of the jack and the plug includes a contact for each of the conductors of the cable. The trunk cable-connector assembly comprises: a second cable including a plurality of second subunits, each of the second subunits comprising a plurality of twisted pairs of conductors; a plug attached to one end of the second cable and connected with the jack of the extension trunk cable; and a plurality of RJ-45 connectors attached to subunits at an opposite end of the second cable.