input ports 1422 on each wss 1408 fig1 illustrates a growth path to a 3 degree wsxc 1500 which comprises an outer layer 1502 of fan out devices wsss 1504 an outer layer 1506 of fan in devices wsss 1508 an inner layer 1510 of fan in devices wsss 1512 arranged in a cascade with respect to outer layer 1506 and an inner layer 1530 of fan out devices wsss 1532 arranged in a cascade with respect to outer layer 1502 the hardware and connections utilized in the upgrade are shown by dashed lines each wss 1504 includes an input port 1518 and a plurality of output ports 1520 each wss 1508 includes a plurality of input ports 1522 and an output port 1524 each wss 1512 includes a plurality of input ports 1514 and an output port 1516 and each wss 1532 includes an input port 1534 and a plurality of output ports 1536 as shown the wsss 1504 in outer layer 1502 couple to either a fan out wss 1532 in layer 1530 a fan in wss 1512 in layer 1510 or a fan in wss 1508 in layer 1506 similarly a fan in wss 1508 couples to either a fan in wss 1512 in layer 1510 a fan out wss 1532 in layer 1530 or a fan out wss 1504 in layer 1502 the free input ports 1514 1522 on the fan in devices and output ports 1520 1536 on fan out devices to enable future growth are depicted by the dotted lines in the drawing fig1 depicts the growth path from the 3 degree wsxc 1500 shown in fig1 to a 6 degree wsxc 1600 the wsxc.