1. A method of upgrading a scalable switching network, comprising: adding a second extra stage of switching elements hardware to the scalable switching network comprising a plurality of internal ports as defined by a post-reconfiguration architecture, said scalable switching network comprising a non-redundant multistage interconnection network having a plurality of stages of switching elements with a first stage and a last stage, a first extra stage of switching elements, a first cyclic group interstage interconnection (CGISIC) network connecting the extra stage of switching elements with either the first stage or the last stage, a plurality of stages of switching elements, a plurality of internal ports, a plurality for external ports, and a plurality of internal connections, wherein the internal ports and external ports are coupled to one of the switching elements and the internal connections are coupled to two of the internal ports; assigning to each internal port a corresponding port defined by the post-reconfiguration architecture; rewiring any internal port on the basis of the post-reconfiguration architecture; and the rewiring comprises: selecting a selected port of the plurality of internal ports that is not coupled to the corresponding port assigned to said selected port; breaking a first connection coupled to the selected port, if the selected port is coupled to the first connection; breaking a second connection coupled to the corresponding port assigned to the selected port, if the corresponding port assigned to the selected port is coupled to said second connection; and connecting the selected port to the corresponding port assigned to the selected port by coupling a third connection to the selected port and to the corresponding port assigned to the selected port, and the post-reconfiguration architecture comprises: the non-redundant multistage interconnection network, the first extra stage of switching elements; the second extra stage of switching elements; a second CGISIC network connecting either the first stage or the last stage of the non-redundant switching network to the second extra stage of switching elements; a third CGISIC network connecting the second extra stage of switching elements to the first extra stage of switching elements.