Flexible crossbar switching fabric

• US 7,173,906 B2
• Filed: 03/15/2002
• Issued: 02/06/2007
• Est. Priority Date: 09/28/2001
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Raghunathan, Anand, Ravi, Srivaths, Chang, Jacob
• Primary Examiner(s): Pham; Chi
• Assistant Examiner(s): Jagannathan; Melanie
• Application Number:
  US10/097,582
• Publication Number:
  US 20030063605A1
• Time in Patent Office: 1,789 Days
• Field of Search: None
• US Class Current: 370/230
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 49/101 using crossbar or matrix
• CPC Class Codes: H04L 49/205 Quality of Service based
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3018 Input queuing

Abstract

A crossbar switching fabric comprising a plurality of crossbar input ports and a plurality of crossbar output ports. The traffic from at least one source is directed to more than one of the plurality of crossbar input ports. The traffic from more than one crossbar output port is directed to at least one destination.

Claims

1. A crossbar switching fabric comprising:

a plurality of crossbar input ports and

a plurality of crossbar output ports,

wherein traffic from at least one source is directed to more than one of said plurality of crossbar input ports, and

wherein traffic from more than one crossbar output port is directed to at least one destination

wherein k×

k′

requests are generated for each routing request coming from an input source, wherein k corresponds to a level of flexibility offered by the crossbar switch and k′

is greater than 1 and less than or equal to k.

2. The crossbar switching fabric of claim 1, wherein an input flexibilty layer is inserted between the traffic sources the crossbar input ports.

3. The crossbar switching fabric of claim 1, wherein an output flexibilty layer is inserted between the traffic destinations and the crossbar output ports.

4. The crossbar switching fabric of claim 1, wherein if src_i represents one source and inp_i are plurality of inputs corresponding to the plurality of input ports, then traffic is directed in such a way that src_i is directed to all inputs corresponding to inp_i . . . inp_i+k.

5. The crossbar switching fabric of claim 4, wherein if i+k exceeds the number of inputs, ten traffic is wrapped around by redirecting traffic intended for inputs corresponding to i+k that exceed the number of inputs to inputs 1 . . . i.

6. The crossbar switching fabric of claim 1, wherein if src_i represents one source and inp_i are the plurality of inputs corresponding to the plurality of input ports, n represents the number of inputs, then traffic is directed in such a way that src_i is directed to all inputs corresponding to inp_i . . . inp_max(i+k,n).

7. The crossbar switching fabric of claim 6, wherein sources ports known to have less traffic are designated to be last n−

k+2 sources, where n is a number of sources.

8. The crossbar switching fabric of claim 4, wherein the fabric comprises an input flexibility layer including at least one multiplexer connected to one of the plurality of input ports.

9. The crossbar switching fabric of claim 4, wherein the fabric comprises an input flexibility layer including at least one multiplexer connected to one of the plurality of input ports.

10. The crossbar switching fabric of claim 8, wherein the multiplexer is a tri-state buffer.

11. The crossbar switching fabric of claim 9, wherein the multiplexer is a tri-state buffer.

12. The crossbar switching fabric of claim 8, wherein flexibility is implemented by varying a size of the multiplexer.

13. The crossbar switching fabric of claim 9, wherein flexibility is implemented by varying a size of the multiplexer.

14. A method of scheduling for a flexible crossbar switch comprising:

a) generating k² requests for each routing request coming from an input source, wherein k corresponds to d level of flexibility offered by the crossbar switch;

b) recombining requests for a same route;

c) sending requests to a crossbar scheduler, and

d) arbitrating requests from different ports making a request if a connection corresponding to the request is granted.

15. The method of claim 14 wherein a priority scheme is used in arbitrating.

16. The method of claim 15, wherein the priority scheme takes into account a quality of service required.