ATM switch

• US 6,570,874 B1
• Filed: 03/03/1999
• Issued: 05/27/2003
• Est. Priority Date: 03/05/1998
• Status: Expired due to Fees

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Nakai, Kohei, Yamanaka, Naoaki, Oki, Eiji
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): Qureshi; Afsar M.
• Application Number:
  US09/261,652
• Time in Patent Office: 1,546 Days
• Field of Search: 370/386,388,387,466,467,395.1,465 359/113,115,117,123,124,128,139
• US Class Current: 370/387
• CPC Class Codes: H04B 10/801 using optical interconnects, e.g. light coupled isolators, circuit board interconnections
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5605 Fibre
• CPC Class Codes: H04L 2012/5672 Multiplexing, e.g. coding, scrambling
• CPC Class Codes: H04L 2012/5681 Buffer or queue management
• CPC Class Codes: H04L 49/1553 Interconnection of ATM switching modules, e.g. ATM switching fabrics
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/455 Provisions for supporting expansion in ATM switches
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0052 Interconnection of switches
• CPC Class Codes: H04Q 2011/006 Full mesh

Abstract

An ATM switch includes a plurality of stages in which each stage has basic switches and the stages are interconnected. The ATM switch includes M×N basic switches per each stage and a part for interconnecting between the stages. The M×N basic switches are divided into N groups. The part connects an output port of each basic switch at a front stage to M input ports of the basic switches at a back stage. At the output port, a wavelength-multiplexing part is used, and, at the input port, a wavelength-demultiplexing part is used. Further, a wavelength-switching part for switching optical signals of M wavelength-multiplexed optical signals arriving from the M wavelength-multiplexing part and outputting the switched wavelength-multiplexed optical signals to the M wavelength-demultiplexing part is used.

Claims

1. An ATM switch including S stages (S is an integer and 2<

=S), wherein said each stage includes a plurality of basic switches, said ATM switch comprising;

M×

N (each of M and N is an integer) basic switches per said each stage; and

interconnecting means for interconnecting between said stages,

wherein said M×

N basic switches have N groups, and said interconnecting means connects a jth (j is an integer and 1<

=j<

=N) output port of said each basic switch belonging to an ith (i is an integer and 1<

=i<

=N) group at an (s−

1)th (s is an integer and 2<

=s<

=S) stage to at least one ith input port of said basic switches belonging to a jth group at an sth stage.

2. The ATM switch as claimed in claim 1, wherein said interconnecting means includes means, which is provided at said each input port, for passing cells that are destined for a desired destination selectively among other cells.

3. The ATM switch as claimed in claim 1, wherein said interconnecting means includes means, which is provided at said each output port, for passing cells that are destined for a desired destination selectively among other cells.

4. The ATM switch as claimed in claim 1, wherein said interconnecting means comprises:

means for converting an electronic-signal cell which is output from said output port into a first wavelength-multiplexed optical signal which includes a plurality of optical signals which have different wavelengths and for outputting the first wavelength-multiplexed optical signal;

means for generating a second wavelength-multiplexed optical signal by switching optical signals and outputting the second wavelength-multiplexed optical signal; and

means for converting said second wavelength-multiplexed optical signal into electronic-signal cells and inputting at least one said electronic-signal cells to the input port.

5. The ATM switch as claimed in claim 1, wherein said interconnecting means comprises:

means for converting a first electronic-signal cell which is output from said output port into N optical-signal cells which have different wavelengths;

wavelength-multiplexing means for generating a wavelength-multiplexed optical signal by wavelength-multiplexing said N optical-signal cells;

wavelength-demultiplexing means for wavelength-demultiplexing a wavelength-multiplexed optical signal into N optical-signal cells which have different wavelengths;

means for converting said N optical-signal cells into N second electronic-signal cells;

input means for inputting at least one of said second electronic-signal cells to said input port; and

wavelength-switching means for switching optical signals of M said wavelength-multiplexed optical signals arriving from said wavelength-multiplexing means and for outputting the switched wavelength-multiplexed optical signals to said wavelength-demultiplexing means,

wherein said wavelength-switching means is provided between said wavelength-multiplexing means which is connected to jth output ports of said basic switches belonging to said ith group at said (s−

1)th stage and said wavelength-demultiplexing means which is connected to ith input ports of said basic switches belonging to said jth group at said sth stage.

6. The ATM switch as claimed in claim 5, wherein said input means comprises means for passing only electronic-signal cells that are destined for a desired destination selectively among said electronic-signal cells.

7. The ATM switch as claimed in claim 5, wherein said ATM switch further comprises means for converting said each electronic-signal cell output from said output port into an optical-signal cell which has a wavelength corresponding to the destination of the electronic-signal cell.

8. The ATM switch as claimed in claim 5, wherein said wavelength-switching means includes a barrel shifter which outputs an optical signal of a pth (p=1,2, . . . ,N) wavelength in the mth (m=1,2, . . . ,M) wavelength-multiplexed optical signal into an (m+p)th output of the barrel shifter, wherein if m+p is k (k is an integer) more than the number of said wavelength-demultiplexing means, the barrel shifter outputs the optical signal into an ((m+p)−

k)th output of the barrel shifter.

9. The ATM switch as claimed in claim 1, wherein the ATM switch further comprises speed-conversion means for converting the speed of electronic-signal cells output from said output port.

10. The ATM switch as claimed in claim 9, wherein said speed-conversion means comprises:

at least a cell buffer; and

means for controlling the ratio between the writing-clock speed of the cell buffer and the reading-clock speed of the cell buffer.

11. The ATM switch as claimed in claim 9, wherein said speed-conversion means comprises:

at least a cell buffer; and

means for controlling the ratio between the number of bit expansion data at the input side of the cell buffer and the number of bit expansion data at the output side of the cell buffer.

12. The ATM switch as claimed in claim 1, wherein the ATM switch further comprises:

means for monitoring the arriving rate of said electronic-signal cells output from said output port; and

means for converting the speed of the electronic-signal cells according to the arriving rate.

13. The ATM switch as claimed in claim 1, wherein the ATM switch further comprises:

at least a cell buffer which temporarily stores said electronic-signal cells output from said output port;

means for monitoring the rate of said electronic-signal cells arriving at said cell buffer; and

means for establishing a plurality of ATM connections between said basic switches so as to equalize the cell-transmission rates of the ATM connections by using the arriving rate.

14. The ATM switch as claimed in claim 9, wherein the ATM switch further comprises means for establishing routes of ATM connections having a plurality of service classes.

15. The ATM switch as claimed in claim 1, wherein the ATM switch further comprises:

monitoring means for monitoring the arriving rate of said electronic-signal cells;

detecting means for detecting traffic congestion of a route between said basic switches by using the arriving rate; and

means for prohibiting the ATM switch from establishing an ATM connection on the route in which said traffic congestion is detected.

16. The ATM switch as claimed in claim 15, wherein said monitoring means and detecting means are provided at the input port of said basic switch.

17. The ATM switch as claimed in claim 15, wherein said detecting means includes means for transmitting the result of the detection to at least one basic switch.

18. The ATM switch as claimed in claim 1, wherein the ATM switch further comprises:

monitoring means for monitoring the residual bandwidth of a port of said basic switch;

means for sending an RM (Resource Management) cell to a plurality of routes;

sending-back means for receiving and sending back the RM cell; and

prohibiting means for prohibiting the ATM switch from establishing an ATM connection on a specific route according to the RM cell which is sent back,

wherein, if said monitoring means detects that the residual bandwidth is less than a predetermined value, said sending-back means includes information of traffic congestion into the RM cell and sends back the RM cell, and said prohibiting means prohibits the ATM switch from establishing an ATM connection on a route indicated by the content of the RM cell which is sent back.

19. The ATM switch as claimed in claim 18, wherein said prohibiting means includes means for adding a header for avoiding a congested route to a cell according to the content of the RM cell.

20. A device in an ATM switch in which a plurality of stages are interconnected, wherein each of said stages has a plurality of basic switches and said device converts an electronic-signal cell output from an output port of a basic switch in said basic switches into a wavelength-multiplexed optical signal, said device comprising:

means for dividing said electronic-signal cell into a plurality of electronic-signal cells;

converting means for converting said electronic-signal cells into optical-signal cells of different wavelengths; and

means for wavelength-multiplexing said optical-signal cells,

wherein, at the destination of said each optical-signal cell, said each optical-signal cell is converted into an electronic-signal cell and the electronic-signal cell is input into an input port by being selected among electronic-signal cells.

21. The device as claimed in claim 20, wherein said device includes means for inputting said electronic-signal cell into said converting means after converting the speed of said electronic-signal cell.

22. A device in an ATM switch in which a plurality of stages are interconnected, wherein the stage has a plurality of basic switches, and said device converts a wavelength-multiplexed optical signal in which a plurality of electronic-signal cells of different destinations are wavelength-multiplexed into electronic-signal cells and inputs one of the electronic-signal cells into an input port of said basic switch, said device comprising:

means for generating a plurality of optical-signal cells by wavelength-demultiplexing said wavelength-multiplexed optical signal;

means for converting said optical-signal cells into said electronic-signal cells; and

means for selecting an electronic-signal cell destined for the input port among said electronic-signal cells and inputting the selected electronic-signal cell to the input port.