A switching device comprises at least two base racks, each base rack including a switch card in communication with a line card across a backplane, the line card having at least an external port. The at least two base racks are coupled such that the switch cards of each are linked. A method for switching a packet comprises introducing the packet into an external port on a first base rack, transmitting the packet from a first cascade port on the first base rack to a second cascade port on a second base rack, and sending the packet out of the second base rack through a second external port.