US5570348A
Expired / Lapsed
US
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Method and apparatus for enqueueing data cells in an ATM switch fabric architecture
Assignee: PMC-SEIRRA Inc
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Filing: 1995-05-11
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Granted: 1996-10-29
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Expires: 2015-05-11
Abstract
Abstract An ATM switching system architecture of a switch fabric-type is built of, a plurality of ATM switch element circuits and routing table circuits for each physical connection to/from the switch fabric. A shared pool of memory is employed to eliminate the need to provide memory at every crosspoint. Each routing table maintains a marked interrupt linked list for storing information about which ones of its virtual channels are experiencing congestion. This linked list is available to a processor in the external workstation to alert the processor when a congestion condition exists in one of the virtual channels. The switch element circuit typically has up to eight 4-bit-wide nibble inputs and eight 4-bit-wide nibble outputs and is capable of connecting cells received at any of its inputs to any of its outputs, based on the information in a routing tag uniquely associated with each cell.
Inventors
- 👤 Brian D. Holden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:52
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; C; C07; C07K; C07K14/00; C07K14/195; C07K14/32; C07K14/325; H04L49/00; H04L49/10; H04L49/104; H04L49/105; H04L49/108; H04L49/20; H04L49/201; H04L49/203; H04L49/25; H04L49/253; H04L49/255; H04L49/30; H04L49/3081; H04L49/309; H04J; H04J2203/00; H04J2203/0001; H04J2203/0064; H04J2203/0067; H04J2203/0071; H04L2012/5629; H04L2012/5631; H04L2012/5632; H04L2012/5635; H04L2012/5638; H04L2012/5646; H04L2012/5651; H04L2012/5678; H04L2012/5681; H04L2012/5682
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
87 words
An ATM switching element comprising: a data input coupled to an ATM cell output of a source; a back-pressure output coupled to said source for issuing a back-pressure signal to block transmission of cells to said data input; control means coupled to said back-pressure output for asserting back-pressure responsive to congestion within said switching element variable delay means for delaying said back-pressure signal responsive to a delay value stored in a register within the ATM switching element; and input port means for externally adjusting said delay value.
Claim 2
Dependent Claim
87 words
An ATM switching element comprising: a data input coupled to an ATM cell output of a source; a back-pressure output coupled to said source for issuing a back-pressure signal to block transmission of cells to said data input; control means coupled to said back-pressure output for asserting back-pressure responsive to congestion within said switching element variable delay means for delaying said back-pressure signal responsive to a delay value stored in a register within the ATM switching element; and input port means for externally adjusting said delay value.
Claim 3
Dependent Claim
183 words
In an ATM switching element employing a cell memory pool, a method for providing back-pressure to a plurality of inputs and a plurality of priorities, comprising the steps of: receiving a cell having one of said plurality of priority levels from one of said plurality of inputs; thereafter enqueuing said cell by recording said cell in a first memory location in the cell memory pool; using an address of said first memory location to obtain an address of a second memory location within an index memory; recording a reference specifying said one of said plurality of priority levels and said one input at said second memory location; incrementing a cell count indicator associated with said one of said plurality of priority levels and said one input; thereafter comparing said cell count indicator to a predetermined threshold to obtain an indication of back-pressure necessity for said one of said plurality of priority levels and said one input; and thereafter upon a positive indication of back-pressure necessity, asserting a back-pressure signal associated with said one input and said one of said plurality of priority levels.
Claim 4
Dependent Claim
183 words
In an ATM switching element employing a cell memory pool, a method for providing back-pressure to a plurality of inputs and a plurality of priorities, comprising the steps of: receiving a cell having one of said plurality of priority levels from one of said plurality of inputs; thereafter enqueuing said cell by recording said cell in a first memory location in the cell memory pool; using an address of said first memory location to obtain an address of a second memory location within an index memory; recording a reference specifying said one of said plurality of priority levels and said one input at said second memory location; incrementing a cell count indicator associated with said one of said plurality of priority levels and said one input; thereafter comparing said cell count indicator to a predetermined threshold to obtain an indication of back-pressure necessity for said one of said plurality of priority levels and said one input; and thereafter upon a positive indication of back-pressure necessity, asserting a back-pressure signal associated with said one input and said one of said plurality of priority levels.
Claim 5
Dependent Claim
103 words
The method of claim 2 further comprising the steps of: dequeuing the cell by transferring the cell from said first memory location to an output of the switching element; using said address of said first memory location to obtain said address of said second memory location; thereafter retrieving said reference specifying said one of said plurality of priority levels and said one input from said second memory location; using said reference to identify said cell count indicator associated with said one input; and thereafter decrementing said cell count indicator associated with said one of said plurality of priority levels and said one input.
Claim 6
Dependent Claim
161 words
In an ATM switching element employing a cell memory pool, a method for providing back-pressure to a plurality of priorities, comprising the steps of: receiving a cell via an input of the switching element; thereafter enqueuing said cell by recording said cell in a first memory location in the cell memory pool; decrementing an empty cell indicator, said empty cell indicator being an enumeration of empty cells within said cell memory pool; comparing said empty cell indicator to a threshold associated with a first priority to obtain an indication of back-pressure necessity for said first priority; upon a positive indication of back-pressure necessity for said first priority, asserting a back-pressure signal associated with said first priority; comparing said empty cell indicator to a threshold associated with a second priority to obtain an indication of back-pressure necessity for said second priority; and upon a positive indication of back-pressure necessity for said second priority, asserting a back-pressure signal associated with said second priority.
Claim 7
Dependent Claim
161 words
In an ATM switching element employing a cell memory pool, a method for providing back-pressure to a plurality of priorities, comprising the steps of: receiving a cell via an input of the switching element; thereafter enqueuing said cell by recording said cell in a first memory location in the cell memory pool; decrementing an empty cell indicator, said empty cell indicator being an enumeration of empty cells within said cell memory pool; comparing said empty cell indicator to a threshold associated with a first priority to obtain an indication of back-pressure necessity for said first priority; upon a positive indication of back-pressure necessity for said first priority, asserting a back-pressure signal associated with said first priority; comparing said empty cell indicator to a threshold associated with a second priority to obtain an indication of back-pressure necessity for said second priority; and upon a positive indication of back-pressure necessity for said second priority, asserting a back-pressure signal associated with said second priority.
Claim 8
Dependent Claim
29 words
The method of claim 4 further comprising the step of time-domain multiplexing said back-pressure signal associated with said first priority with said back-pressure signal associated with said second priority.
Claim 9
Independent Claim
104 words
A method for queuing incoming data cells in a switching system, the data cells being received from a plurality of connections, each of the data cells having an associated priority, the method comprising the steps of: queuing the incoming data cells with respect to each other in a queue according to the associated priority of each of the incoming data cells; maintaining a count of the incoming data cells from each of the connections which remain in the queue; and generating feedback signals to selected data cell sources when the count for connections corresponding to the selected data cell sources exceeds a first number.
Claim 10
Independent Claim
104 words
A method for queuing incoming data cells in a switching system, the data cells being received from a plurality of connections, each of the data cells having an associated priority, the method comprising the steps of: queuing the incoming data cells with respect to each other in a queue according to the associated priority of each of the incoming data cells; maintaining a count of the incoming data cells from each of the connections which remain in the queue; and generating feedback signals to selected data cell sources when the count for connections corresponding to the selected data cell sources exceeds a first number.
Claim 11
Independent Claim
116 words
A method for monitoring congestion on channels in a switching system, comprising the steps of: storing a first data cell in a queue, the first data cell comprising a routing tag field, the routing tag field corresponding to a first channel; comparing an actual data cell count for the first channel to a predetermined count; generating an interrupt signal if the actual data cell count is greater than the predetermined count and the first channel is not marked; marking the first channel by setting a bit if the first channel is not marked; and placing the first channel on a linked list of congested channels if the first channel is not already on the linked list.
Claim 12
Independent Claim
116 words
A method for monitoring congestion on channels in a switching system, comprising the steps of: storing a first data cell in a queue, the first data cell comprising a routing tag field, the routing tag field corresponding to a first channel; comparing an actual data cell count for the first channel to a predetermined count; generating an interrupt signal if the actual data cell count is greater than the predetermined count and the first channel is not marked; marking the first channel by setting a bit if the first channel is not marked; and placing the first channel on a linked list of congested channels if the first channel is not already on the linked list.
Claim 13
Dependent Claim
37 words
The method of claim 7, further comprising the steps of: receiving the interrupt signal; reading the congested channels in the linked list; and taking action to resolve the congestion for the congested channels in the linked list.
Claim 14
Dependent Claim
22 words
The method of claim 8 wherein the step of taking action comprises sending a feedback message to selected sources of data cells.
Claim 15
Dependent Claim
16 words
The method of claim 8 wherein the step of taking action comprises changing the predetermined count.
References Cited (Backward Citations)
US5083269A
Cited
US5099475A
Cited
US5285444A
Cited
US5280470A
Cited
US5144619A
Cited
US5317561A
Cited
US5233606A
Cited
US5313454A
Cited
US5325356A
Cited
US5392280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-29 | 2000-04-29 | 2000-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-29 | 2004-04-29 | 2004-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-29 | 2008-04-29 | 2008-10-29 | $7700.00 | Window Closed / Lapsed |