Packet unstopper system for a parallel packet switch

• US 7,391,766 B2
• Filed: 11/26/2003
• Issued: 06/24/2008
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Poret, Michel, Glaise, Rene, Gallezot, Rene, Le Maut, Francois
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): O CONNOR, BRIAN T
• Application Number:
  US10/723,503
• Publication Number:
  US 20040141505A1
• Time in Patent Office: 1,672 Days
• Field of Search: 370/387, 370/398, 370/412, 370/416, 370/388, 370/395.7, 710/57, 710/240, 710/241
• US Class Current: 370/387
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5635 Backpressure, e.g. for ABR
• CPC Class Codes: H04L 2012/565 Sequence integrity
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04L 2012/5682 Threshold; Watermark
• CPC Class Codes: H04L 49/1523 Parallel switch fabric planes
• CPC Class Codes: H04L 49/153 ATM switching fabrics having parallel switch planes
• CPC Class Codes: H04L 49/256 Routing or path finding in ATM switching fabrics
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/3045 Virtual queuing
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/50 Overload detection or protection within a single switching element

Abstract

A system for controlling egress buffer saturation includes, for each data packet flow, a comparator for comparing the number of data packets ‘WPC’ temporarily stored within an egress buffer to a predefined threshold value ‘WPCth’. The packet sequence number ‘PSNr’ of a last received in-sequence data packet and each highest packet sequence number ‘HPSNj’ received through respective ones of the plurality of switching planes is stored. By comparing the last received in-sequence packet sequence number ‘PSNr’ to each highest packet sequence number ‘HPSNj’ when the number of data packets ‘WPC’ exceeds the predefined threshold value ‘WPCth’ a determination as to which switching plane(s), among the plurality of switching planes, to unstop the flow of data packets can be made.

Claims

1. A method comprising:

a) receiving packets through a plurality of switching planes;

b) identifying a packet sequence number for a last received in-sequence packet;

c) identifying highest packet sequence number for packets received through each of the plurality of switching planes; and

d) determining at least one of the plurality of switching planes to unstop based upon the packet sequence number for the last received in-sequence packet number and the highest sequence number for at least one of the plurality of switching planes.

2. The method of claim 1 further including

e) comparing number of packets temporarily stored in a buffer with a predefined threshold value.

3. The method of claim 2 wherein the at least one of the plurality of switching planes is determined only if the number of packets stored in the buffer is equal or greater than a predefined threshold value.

4. The method of claim 3 wherein c) includes comparing the last received in-sequence packet number with the highest sequence number for each of the plurality of switching planes.

5. The method of claim 1 further including releasing from the at least one of the plurality of switching planes so determined, at least one packet whose sequence number is next to the last received in-sequence packet number.