Store and forward switch device, system and method

• US 20040039986A1
• Filed: 08/23/2002
• Published: 02/26/2004
• Est. Priority Date: 08/23/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Harriman, David, Solomon, Gary A.
• Granted Patent: US 7,251,704 B2
• Time in Patent Office: Days
• US Class Current: 714/799
• CPC Class Codes: H04L 49/252 Store and forward routing
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/555 Error detection

Abstract

Disclosed are a system and method for forwarding data packets from ingress ports to egress ports on a switch. A forwarding circuit may commence forwarding data packets from an ingress port through a switch fabric to a transmit queue of an egress port prior to completion of a checksum operation.

Claims

1. A method comprising:

receiving a data packet at an ingress port of a switch;

initiating a checksum operation on a portion of the received data packet; and

commencing forwarding the received data packet through a switch fabric to a transmit queue of an egress port of the switch prior to completion of the checksum operation.

2. The method of claim 1, the method further comprising selectively transmitting the forwarded data packet from the transmit queue in response to a valid CRC indication from the checksum operation.

3. The method of claim 2, the method further comprising selectively dropping the forwarded data packet from the transmit queue in response to an invalid CRC indication from the checksum operation.

4. The method of claim 1, the method further comprising inserting a packet invalid symbol into the forwarded data packet in response to an invalid CRC indication from the checksum operation.

5. The method of claim 1, the method further comprising selecting the egress port based upon a portion of the received data packet.

6. The method of claim 5, the method further comprising:

associating the received data packet with a data packet type based upon a portion of the received data packet;

extracting destination information from a portion of the received data packet based upon the associated data packet type; and

selecting the egress port based upon the destination information.

7. The method of claim 6, the method further comprising:

selecting the egress port based upon a physical address in the received data packet with the egress port if the received data packet is associated with a request data packet type; and

selecting the egress port based upon an identifier of a source of a request data packet if the received data packet is associated a request completion data packet type.

8. The method of claim 1, the method further comprising:

determining an availability of the egress port to transmit the received data packet; and

selectively forwarding the received data packet to the transmit queue based upon the availability of the egress port.

9. A switch comprising:

a plurality of ports coupled to a switch fabric, at least one port comprising a transmit queue;

a checksum circuit to execute a checksum operation on at least a portion of a data packet received at an ingress port; and

a forwarding circuit to commence forwarding the received data packet through the switch fabric to a transmit queue of an egress port prior to completion of the checksum operation.

10. The switch of claim 9, wherein the egress port comprises logic to selectively transmit the forwarded data packet from the transmit queue in response to a valid CRC indication from the checksum operation.

11. The switch of claim 10, wherein the egress port comprises logic to selectively drop the forwarded data packet from the transmit queue in response to an invalid CRC indication from the checksum operation.

12. The switch of claim 9, the switch further comprising logic to insert a packet invalid symbol into the forwarded data packet in response to an invalid CRC indication from the checksum operation.

13. The switch of claim 9, wherein the forwarding circuit comprises logic to select the egress port based upon a portion of the received data packet.

14. The switch of claim 13, wherein the forwarding circuit further comprises:

logic to associate the received data packet with a data packet type based upon a portion of the received data packet;

logic to extract destination information from a portion of the received data packet based upon the associated data packet type; and

logic to select the egress port based upon the destination information.

15. The switch of claim 14, wherein the forwarding circuit further comprises:

logic to select the egress port based upon a physical address in the received data packet with the egress port if the received data packet is associated with a request data packet type; and

logic to select the egress port based upon an identifier of a source of a request data packet if the received data packet is associated a request completion data packet type.

16. The switch of claim 9, wherein the forwarding circuit further comprises:

logic to determine an availability of the egress port to transmit the received data packet; and

logic to selectively forward the received data packet to the transmit queue based upon the availability of the egress port.

17. A system comprising:

a switch comprising;

a plurality of ports coupled to a switch fabric, at least one port comprising a transmit queue;

a checksum circuit to execute a checksum operation on at least a portion of a data packet received at an ingress port; and

a forwarding circuit to commence forwarding the received data packet through the switch fabric to a transmit queue of an egress port prior to completion of the checksum operation;

a host processing system coupled to an upstream port of the switch through a root device; and

one or more devices coupled to downstream ports of the switch.

18. The system of claim 17, wherein the egress port comprises logic to selectively transmit the forwarded data packet from the transmit queue in response to a valid CRC indication from the checksum operation.

19. The system of claim 18, wherein the egress port comprises logic to selectively drop the forwarded data packet from the transmit queue in response to an invalid CRC indication from the checksum operation.

20. The system of claim 17, wherein the switch further comprises logic to insert a packet invalid symbol into the forwarded data packet in response to an invalid CRC indication from the checksum operation.

21. The system of claim 17, wherein the forwarding circuit comprises logic to select the egress port based upon a portion of the received data packet.

24. The system of claim 17, wherein the forwarding circuit further comprises:

logic to determine an availability of the egress port to transmit the received data packet; and

logic to selectively forward the received data packet to the transmit queue based upon the availability of the egress port.

25. The system of claim 17, wherein the switch comprises logic to emulate the presence of a PCI-to-PCI bridge in response to receipt of a configuration request packet at the upstream port.

26. The system of claim 17, wherein at least one downstream port is coupled to an of the devices comprises a graphics controller.

27. The system of claim 17, wherein at least one downstream port is coupled to a small computer system interface.

28. The system of claim 17, wherein at least one downstream port is coupled to an Ethernet controller.

29. The system of claim 17, wherein at least one downstream port is coupled to a Fiberchannel interface.

30. The system of claim 17, wherein at least one downstream port is coupled to a serial ATA device.

22. The system of claim 22, wherein the forwarding circuit further comprises:

logic to associate the received data packet with a data packet type based upon a portion of the received data packet;

logic to extract destination information from a portion of the received data packet based upon the associated data packet type; and

logic to select the egress port based upon the destination information.

23. The system of claim 22, wherein the forwarding circuit further comprises:

logic to select the egress port based upon a physical address in the received data packet with the egress port if the received data packet is associated with a request data packet type; and

logic to select the egress port based upon an identifier of a source of a request data packet if the received data packet is associated a request completion data packet type.