* h stands for the switches levels number, i.e. the fat tree is of height h,
* without the processing nodes. m_i stands for the number of lower level nodes
* connected to a node in level i. w_i stands for the number of upper levels
* h stands for the switches levels number, i.e. the fat tree is of height h,
* without the processing nodes. m_i stands for the number of lower level nodes
* connected to a node in level i. w_i stands for the number of upper levels