Methods and apparatus for high-speed data transfer that minimizes conductors

• US 6,091,729 A
• Filed: 11/26/1997
• Issued: 07/18/2000
• Est. Priority Date: 11/27/1996
• Status: Expired due to Fees

• Current Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Original Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Inventors: Dove, Jason W.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US08/979,383
• Time in Patent Office: 965 Days
• Field of Search: 370/359, 370/362, 370/364, 370/389, 370/395, 370/419, 370/428, 370/360
• US Class Current: 370/395.4
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5605 Fibre
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/5665 Interaction of ATM with other protocols
• CPC Class Codes: H04L 2012/5674 Synchronisation, timing recovery or alignment
• CPC Class Codes: H04L 49/107 using shared medium
• CPC Class Codes: H04L 49/405 Physical details, e.g. power supply, mechanical construction or backplane of ATM switches

Abstract

A cell bus, which reduces the number of conductors required to transfer data in a telecommunications switching fabric, contains a plurality of conductors, Data[X:0], for transmitting information. A cell bus interface generates a cell bus frame that includes a plurality of words, "X" bits in length, of both data and control information that includes, in part, routing information for the data. As a result of encapsulating data and control information into and cell bus frame for transmission on the Data[X:0] conductors, the number of conductors required to transmit data is reduced. An asynchronous transfer mode (ATM) switching fabric, which includes a plurality of cell buses configured in a point to point fashion between a cell routing unit (CRU)/ATM fiber bank interface unit (AFIU) and a plurality of optical line units (OLUs), is also disclosed.

Claims

1. A switching fabric comprising:

at least one switch;

a plurality of line units;

a cell bus comprising a plurality of conductors that electrically couple a switch to a plurality of line cards in said switching fabric, said cell bus for transmitting a cell of a predetermined size; and

said switching fabric comprising a minimum bandwidth requirement that specifies delivery of a predetermined numbers of said cells per unit of time to said line cards via said cell bus, said switching fabric including a plurality of control parameters that control flow of said cells from said switch to said line cards; and

cell bus interface for transmitting a cell bus frame on said cell bus, said cell bus frame comprising said cell and said control parameters, such that a maximum size of a cell bus frame permits transmission of said cell and said control parameters on said conductors to meet said minimum bandwidth requirement, whereby encapsulating said control parameters for said switching fabric into said cell bus frame reduces the number of conductors in said switching fabric.

2. The switching fabric as set forth in claim 1, wherein said cell bus further comprises:

a cell clock line for conducting a cell clock that provides timing for said cell bus; and

a cell sync line for conducting a cell sync signal that delineates between said cell bus frames.

3. The switching fabric as set forth in claim 1, wherein said cell bus comprises a point to point bus between said switch and said line cards.

4. The switching fabric as set forth in claim 1, wherein said cell bus comprises a bus shared among a plurality of cell bus interfaces.

5. The switching fabric as set forth in claim 1, wherein said control parameter further comprises a check sum to validate said cell bus frame.

6. The switching fabric as set forth in claim 1, wherein said cell bus interface comprises circuitry for transmitting and receiving data for bi-directional transmission of data on said bus.

7. The switching fabric as set forth in claim 1, wherein said cell comprises an asynchronous transfer mode (ATM) cell of 53 bytes.

8. The switching fabric as set forth in claim 1, wherein said control parameter comprises an idle bit that indicates an active cell bus frame.

9. A method for reducing a number of conductors required on a switching fabric, said method comprising the steps of:

generating a cell bus comprising a plurality of conductors that electrically couple a switch to a plurality of line cards in a switching fabric, said cell bus for transmitting a cell of a predetermined size and said switching fabric comprising a minimum bandwidth requirement that specifies delivery of a predetermined numbers of said cells per unit of time to said line cards via said cell bus, said switching fabric including a plurality of control parameters that control flow of said cells from said switch to said line cards; and

generating a cell bus frame for transmission on said cell bus, said cell bus flame comprising said cell and said control parameters, such that a maximum size of a cell bus frame permits transmission of said cell and said control parameters on said conductors to meet said minimum bandwidth requirement, whereby encapsulating said control parameters for said switching fabric into said cell bus frame reduces the number of conductors in said switching fabric.

10. A line card for a telecommunications device comprising:

a plurality of conductors that electrically couple said line card to a switch in a switching fabric, said conductors for transmitting a cell of a predetermined size; and

said switching fabric comprising a minimum bandwidth requirement that specifies delivery of a predetermined number of said cells per unit of time to said line card via said conductors, said switching fabric including a plurality of control parameters that control flow of said cells from said switch to said line card; and

a cell bus interface, coupled to said conductors, for transmitting a cell bus frame on said conductors, said cell bus frame comprising said cell and said control parameters, such that a maximum size of a cell bus frame permits transmission of said cell and said control parameters on said conductors to meet said minimum bandwidth requirement, whereby encapsulating said control parameters for said switching fabric into said cell bus frame reduces the number of conductors in said line card.

11. The line card as set forth in claim 10, further comprising a cell bus interface for generating said cell bus frame for transmission upstream.

12. The line card as set forth in claim 10, wherein said conductors further comprise:

a cell clock line for receiving a cell clock that provides timing for said cell bus frame; and

a cell sync line for receiving a cell sync signal that delineates between said cell bus frames.

13. The line card as set forth in claim 10, wherein said control parameter further comprises a check sum to validate said cell bus frame.

14. The line card as set forth in claim 10, wherein said cell comprises an asynchronous transfer mode (ATM) cell of 53 bytes.

15. The line card as set forth in claim 10, wherein said control parameter comprises an idle bit that indicates an active cell bus frame.