Crossbar switching matrix with broadcast buffering

A broadcast (BC)/unicast (UNI) buffer apparatus for use with an N×N crossbar switch matrix having N input ports and N output ports and adapted to switch variable length data packets, and N interface (I/F) circuits for interfacing physical ports to the switch matrix, the apparatus comprising:

• broadcast storage means adapted to store broadcast packet data output of the switch matrix;
• unicast storage means adapted to store unicast packet data output of the switch matrix;
• steering means operative to either store unicast packet data in the unicast storage means or broadcast packet data in the broadcast storage means, the steering means selecting either the unicast storage means or the broadcast storage means in accordance with a select signal;
• control means operative to halt the transfer and storage of unicast packet data to the unicast storage means upon the arrival of a broadcast packet, whereby the broadcast packet data is stored in the broadcast storage means and transmitted to the I/F circuit, and wherein the transmission and storage of unicast packet data into the unicast storage means is resumed following the completion of transmission of the broadcast packet.

In a switching system including an N×N crossbar switch matrix having N input ports and N output ports and adapted to switch variable length data packets, and N interface (I/F) circuits for interfacing physical ports to the switch matrix, a method of reducing the latency of broadcast packet transmission through the switching system, the method comprising the steps of:

• storing unicast packet data in a unicast storage buffer in the absence of a broadcast packet to be transmitted through the switching system;
• halting the transmission of unicast packet data through the switch matrix and the subsequent storage of unicast packet data in the unicast storage buffer;
• storing broadcast packet data in a broadcast storage buffer immediately after it arrival to the switch matrix;
• and
• resuming the transmission through the switch matrix and the subsequent storage in the unicast storage buffer of unicast packet data.