Patent ID: 7492782

Claim:
A high capacity switching apparatus, comprising: N input ports each of which for outputting maximum l cells in a time slot, wherein each of the N input ports includes N virtual output queues (VOQs) which are grouped in l virtual output queue groups with n VOQs in each group; N×N switch fabric having l 2 crossbar switch units (XSUs) for scheduling cells inputted from N input ports based on a first arbitration function based on a round-robin, wherein l VOQ groups are connected to l XSUs; and N output ports each of which connected to l XSUs for selecting one cell from l XSUs in a cell time slot by scheduling cells by a second arbitration function based on a backlog weighed round-robin, which operates independently of the first arbitration function, and transferring the selected cell to its output link, wherein each of N output ports is memory-less type and a cell is selected from scheduling decomposition buffers (SDBs) of the XSUs by an output arbiter in a time slot, a maximum one cell is selected from l SDBs by the output arbiter in a time slot and the SDBs that belongs to the j th output port can be expressed as: ∑ m = 0 l - 1 ⁢ ⁢ SDB ⁡ ( m , ⌊ j n ⌋ , j ⁢ ⁢ mod ⁢ ⁢ n ) .