ATM switching element and method having independently accessible cell memories

United States Patent [m

Holden

[54] ATM SWITCHING ELEMENT AND METHOD HAVING INDEPENDENTLY ACCESSD3LE CELL MEMORIES

[75] Inventor: Brian D. Holden, Sunnyvale, Calif.

[73] Assignee: Integrated Telecom Technology, Santa Clara, Calif.

[21] Appl. No.: 235,006
[22] Filed: Apr. 28,1994

[51] Int. CL6 H04L 12/54

[52] U.S. CI 370/395; 370/352; 370/412;

370/419

[58] Field of Search 370/60, 60.1, 61,

370/85.6, 94.1

[56] References Cited

U.S. PATENT DOCUMENTS

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5,285,444 2/1994 Sakurai et al 370/60

5,317,561 5/1994 Fischer et al 370/60.1 X

5,325,356 6/1994 Lyles 370/60

OTHER PUBLICATIONS

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...

US005583861A [ii] Patent Number: 5,583,861 [45] Date of Patent: Dec. 10,1996

Karol et al., "Input Versus Output Queuing on a Space Division Packet Switch", IEEE Trans. Commun., Dec. 1987, pp. 1347-1356, reprinted in Performance Evaluation, pp. 59-68.

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(List continued on next page.)

Primary Examiner—Douglas W. Olms

Assistant Examiner—Russell W. Blum

Attorney, Agent, or Firm—Townsend and Townsend and

Crew, LLP

[57] ABSTRACT

An ATM switching system architecture of a switch fabrictype 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.

15 Claims, 13 Drawing Sheets

OTHER PUBLICATIONS

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