Crossbar switch utilizing broadcast buffer and associated broadcast buffer management unit

Claims

What is claimed is:

1. A crossbar switching system for switching variable length unicast and broadcast packets, comprising:

an N.times.N crossbar switch matrix comprising N input ports and N output ports, the switch matrix adapted to couple data present at any input port to any output port in accordance with one or more switch configuration commands; and

N interface (I/F) circuits, each I/F circuit coupled to a corresponding input port and output port on the switch matrix, each I/F circuit comprising:

N unicast queues, each unicast queue corresponding to a different output port on the switch matrix;

a broadcast buffer adapted to store a plurality of broadcast packets; and

a broadcast buffer management unit adapted to periodically halt the transmission of unicast packets to said crossbar switch matrix to permit the consecutive transfer of broadcast packets thereto, said broadcast buffer management unit adapted to store broadcast packets arriving to said I/F circuit in said broadcast buffer, said broadcast buffer management unit operative to consecutively transfer the contents of said broadcast buffer to said crossbar switch matrix while the transmission of said unicast packets is suspended, the transmission of said unicast packets resuming following the completion of transmission of said broadcast packets.

2. The system according to claim 1, wherein only one of said N buffer management units on said N I/F cards functions as a master management unit, the remaining functions as slave units.

3. The system according to claim 1, wherein said broadcast buffer management unit is adapted to halt the transmission of unicast packets upon the number of broadcast packets in said broadcast buffer exceeding a predetermined threshold.

4. The system according to claim 1, wherein said broadcast buffer management unit is adapted to halt the transmission of unicast packets upon the length of time from the last broadcast packet transmission exceeding a predetermined threshold.

5. The system according to claim 1, wherein said broadcast buffer management unit is adapted to enable the transmission of a predetermined number of broadcast packets, said predetermined number of packets configurable by a user.

6. The system according to claim 1, wherein said broadcast buffer management unit is adapted to enable the transmission of broadcast packets for a predetermined length of time, said predetermined length of time configurable by a user.

7. The system according to claim 1, wherein each interface circuit is adapted to operate in either a unicast state or a broadcast state, wherein in said unicast state, unicast packets are stored in said unicast queues and transmitted towards said switch matrix while arriving broadcast packets are stored in said broadcast buffer, and wherein in said broadcast state, unicast transmission is suspended and broadcast packets are transmitted from said broadcast buffer to said switch matrix.

8. A crossbar switching system for switching variable length unicast and broadcast packets, comprising:

an N.times.N crossbar switch matrix comprising N input ports and N output ports, the switch matrix adapted to couple data present at any input to any output port in accordance with switch configuration commands, said crossbar switch matrix comprising:

a management bus adapted to send and receive a plurality of broadcast buffer management control and status signals;

a broadcast buffer management unit coupled to said management bus;

N interface (I/F) circuits, each I/F circuit coupled to a corresponding input port and output port on the switch matrix, each I/F circuit comprising:

N unicast queues, each unicast queue corresponding to an output port on the switch matrix;

a broadcast buffer coupled to said management bus, said broadcast buffer adapted to store a plurality of broadcast packets; and

wherein said broadcast buffer management unit adapted to periodically halt the transmission of unicast packets to said crossbar switch matrix to permit the consecutive transfer of broadcast packets thereto, said broadcast buffer management unit adapted to store broadcast packets arriving to said I/F circuit in said broadcast buffer, said broadcast buffer management unit operative to consecutively transfer the contents of said broadcast buffer to said crossbar switch matrix while the transmission of said unicast packets is suspended, the transmission of said unicast packets resuming following the completion of transmission of said broadcast packets.

9. The system according to claim 8, wherein said broadcast buffer management unit is adapted to halt the transmission of unicast packets upon the number of broadcast packets in said broadcast buffer exceeding a predetermined threshold.

10. The system according to claim 8, wherein said broadcast buffer management unit is adapted to halt the transmission of unicast packets upon the length of time from the last broadcast packet transmission exceeding a predetermined threshold.

11. The system according to claim 8, wherein said broadcast buffer management unit is adapted to enable the transmission of a predetermined number of broadcast packets, said predetermined number of packets configurable by a user.

12. The system according to claim 8, wherein said broadcast buffer management unit is adapted to enable the transmission of a broadcast packet for a predetermined length of time, said predetermined length of time configurable by a user.

13. The system according to claim 8, wherein each interface circuit is adapted to operate in either a unicast state or a broadcast state, wherein in said unicast state, unicast packets are stored in said unicast queues and transmitted towards said switch matrix while arriving broadcast packets are stored in said broadcast buffer, and wherein in said broadcast state, unicast transmission is suspended and broadcast packets are transmitted from said broadcast buffer to said switch matrix.