High radix switches are essential for reducing network latency. A possible way to realize them is by using silicon photonic microrings which have been demonstrated to have small foot prints and very fast switching times. By cascading multiple 2 by 2 switches high radix ones can be achieved. However, the scalability of such microring-resonator based switch fabrics is limited by optical power loss and crosstalk. In this work we employ detailed physical layer device models to determine the scalability of such switches. Our results show that a high radix switch with low cross talk and insertion loss is feasible.