Q. Show the Connection between different networks?

The connection between different stages is made in following manner:  all outputs of 1^st crossbar switch of first stage are combined with 1^st input of every switch of middle stage.  (It implies that 1^st output of first page with 1^st middle stage, 2^nd output of first phase with 1^st input of second switches of middle stage and so on...)

The O/P (outputs) of second switch of first phase. Stage are combined with 2^nd input of various switches of second stage (i.e., 1^st O/P of second switch of 1^st stage is joined with 2 input of 1^st switch of middle stage and 2nd output of 2^nd switch of 1^st stage is joined with 2^nd input of 2^nd switch of middle stage and so on.

Similar connections are established between middle phase and output phase (It implies that outputs of 1^st switch of middle phase are connected with 1^st input of different switches of third phase. Permutation matrix of P in the above illustration the matrix entries will be n.