Broadband switch that manages traffic and method therefor

• US 6,188,687 B1
• Filed: 12/30/1997
• Issued: 02/13/2001
• Est. Priority Date: 11/30/1994
• Status: Expired due to Term

• Current Assignee: Verizon Laboratories Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Laboratories Incorporated (Verizon Communications Inc.)
• Inventors: Mussman, Harry Edward, Liu, Stephen S., Chen, Hung-San
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): Duong, Frank
• Application Number:
  US09/000,908
• Time in Patent Office: 1,141 Days
• Field of Search: 370/360, 370/380, 370/387, 370/388, 370/410, 370/907, 370/354, 370/367, 370/485, 370/486, 370/487, 348/7, 348/12
• US Class Current: 370/388
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation
• CPC Class Codes: H04L 7/0337 Selecting between two or more discretely delayed clocks or selecting between two or more discretely delayed received code signals

Abstract

A network (10) includes a broadband customer service module (B-CSM) (20). The B-CSM (20) includes a plurality of feeder interface cards (FICs) (36) and optical line cards (OLCs) (38) which are coupled together through a midplane assembly (34) so that each FIC (36) couples to all OLCs (38) and each OLC (38) couples to all FICs (36) through junctor groups (68). A reference clock which oscillates at a frequency slower than the data rate is routed with payload data so that it receives delays similar to those imposed on the payload data due to processing. At second stage switching fabrics (50) where data need to be extracted from signals flowing within the B-CSM (20), a clock regeneration circuit (32) generates a master clock signal oscillating at twice the data rate and phase synchronized to a delayed reference clock. A geometric compensation scheme corrects for timing skew which occurs when clocks and data are distributed to points or small areas from widely dispersed locations, and when clocks and data are distributed from points or small areas to widely dispersed locations. The B-CSM (20) ranks the junctor groups (68) according to signal occupancy and manages signal traffic to efficiently utilize the FICs (36) and to reduce the probability of signal blocking. The junctor groups (68) can include a number of bidirectional junctors. The bidirectional junctors are configured to carry upstream or downstream signals according to current upstream and downstream signal traffic volume.

Claims

1. A method of operating a switching circuit to manage communication signal traffic, said method comprising the steps of:

performing first stage switching in a first plurality of switching modules;

performing second stage switching in a second plurality of switching modules, wherein each of said first switching modules is coupled to all of said second switching modules and said first and second switching modules are in data communication through a plurality of junctors, a portion of said junctors being configured as bidirectional junctors;

monitoring upstream and downstream signal traffic volume;

controlling, in response to said monitoring step, a number of said bidirectional junctors allocated to upstream signal traffic and a number of said bidirectional junctors allocated to downstream signal traffic; and

directing communication signals through said bidirectional junctors in response to said upstream and downstream signal traffic volume.

2. A method as claimed in claim 1, wherein said junctors are arranged in a plurality of junctor groups and said method further comprises the steps of:

receiving one of said communication signals at one of said first switching modules;

ranking said junctor groups according to junctor occupancy;

selecting one of said junctor groups in response to said ranking step; and

routing said one communication signal through said selected junctor group to one of said second switching modules.

3. A method as claimed in claim 1, wherein said controlling step controls said bidirectional junctors such that said number of said bidirectional junctors allocated to upstream signal traffic is responsive to the volume of upstream signal traffic and said number of said bidirectional junctors allocated to downstream signal traffic is responsive to the volume of downstream signal traffic.

4. A method as claimed in claim 1, wherein each of said bidirectional junctors is coupled to a first upstream fabric located at said first switching module, a first downstream fabric located at said first switching module, a second upstream fabric located at said second switching module, and a second downstream fabric located at said second switching module, and said method further comprises the steps of:

delivering downstream signals from said first downstream fabric to said second switching module via one of said bidirectional junctors;

delivering upstream signals from said second upstream fabric to said first switching module via one of said bidirectional junctors;

receiving said downstream signals at said second downstream fabric when said one bidirectional junctor is configured as a downstream junctor; and

receiving said upstream signals at said first upstream fabric when said one bidirectional junctor is configured as an upstream junctor.

5. A method as claimed in claim 4, further comprising the steps of:

ignoring said downstream signals at said first upstream fabric when said one bidirectional junctor is configured as said downstream junctor; and

ignoring said upstream signals at said second downstream fabric when said one bidirectional junctor is configured as said upstream junctor.

6. A method for operating a broadband video switching circuit to manage communication signal traffic, said method comprising the steps of:

performing first stage switching in a first plurality of switching modules;

performing second stage switching in a second plurality of switching modules, wherein each of said first switching modules is coupled to all of said second switching modules and said first and second switching modules are in data communication through a plurality of junctor groups;

ranking said junctor groups according to junctor occupancy; and

selecting one of said junctor groups to carry a communication signal, said selecting step being responsive to said ranking step.

7. A method as claimed in claim 6, wherein said junctor groups include a plurality of bidirectional junctors and said method further comprises the steps of:

monitoring upstream and downstream signal traffic volume; and

controlling, in response to said monitoring step, a number of bidirectional junctors allocated to upstream signal traffic and a number of bidirectional junctors allocated to downstream signal traffic.

8. A method as claimed in claim 6, wherein said selecting step selects a relatively low-occupancy junctor group over a relatively high-occupancy junctor group.

9. A method as claimed in claim 6, wherein:

each of said junctor groups includes a plurality of individual junctors; and

said method further comprises the step of choosing, from said selected junctor group, one of said individual junctors to carry said communication signal.

10. A method as claimed in claim 9, further comprising the step of routing said communication signal from one of said first switching modules to one of said second switching modules via said one individual junctor.

11. A method as claimed in claim 6, further comprising the steps of:

obtaining a switching request for said communication signal, said switching request originating from a customer site; and

determining whether said communication signal is available at said first and second switching modules.

12. A method as claimed in claim 11, wherein each of said first switching modules is connected to a plurality of feeder channels and said method further comprises the steps of:

selecting one of said feeder channels when said communication signal is not available at said first and second switching modules; and

acquiring, at one of said first switching modules, said communication signal over said one feeder channel.

13. A method as claimed in claim 6, further comprising the steps of:

determining whether said communication signal can be delivered according to a switching request; and

repeating said selecting step for different ones of said junctor groups until said communication signal can be delivered according to said switching request.

14. A method as claimed in claim 13, wherein each of said first switching modules is connected to a plurality of feeder channels and said method further comprises the steps of:

selecting one of said feeder channels to acquire said communication signal at one of said first switching modules; and

repeating said feeder channel selecting step until said communication signal can be delivered according to said switching request.

15. A broadband switching circuit that manages communication signal traffic, said switching circuit comprising:

a plurality of first switching modules;

a plurality of second switching modules, each of said first switching modules being coupled to all of said second switching modules;

a plurality of junctors configured to provide data communication between said first and second switching modules, a portion of said junctors being configured as bidirectional junctors, each of said bidirectional junctors being coupled to a first upstream fabric located at said first switching module, a first downstream fabric located at said first switching module, a second upstream fabric located at said second switching module, and a second downstream fabric located at said second switching module; and

means for directing communication signals through said junctors in response to upstream and downstream signal traffic volume.

16. A switching circuit as claimed in claim 15, further comprising a plurality of feeders, each of which is coupled to at least two of said first switching modules, wherein said feeders are configured to provide data to said first switching modules.

17. A switching circuit as claimed in claim 15, further comprising:

means for monitoring said upstream and downstream signal traffic volume; and

means for controlling said bidirectional junctors such that a number of said bidirectional junctors is responsive to said upstream signal traffic volume and a number of said bidirectional junctors is responsive to said downstream signal traffic volume.

18. A switching circuit as claimed in claim 15, wherein for each of said bidirectional junctors:

said first downstream fabric is configured to deliver downstream signals;

said second upstream fabric is configured to deliver upstream signals;

said second downstream fabric is configured to receive said downstream signals when said bidirectional junctor is configured as a downstream junctor; and

said first upstream fabric is configured to receive said upstream signals when said bidirectional junctor is configured as an upstream junctor.

19. A switching circuit as claimed in claim 18, wherein:

said first upstream fabric is configured to ignore said downstream signals when said bidirectional junctor is configured as said downstream junctor; and

said second downstream fabric is configured to ignore said upstream signals when said bidirectional junctor is configured as said upstream junctor.

20. A broadband switching circuit that manages communication signal traffic, said switching circuit comprising:

a plurality of first switching modules;

a plurality of second switching modules, each of said first switching modules being coupled to all of said second switching modules;

a plurality of junctors configured to provide data communication between said first and second switching modules, said junctors being arranged in a plurality of junctor groups;

means for ranking said junctor groups according to junctor occupancy;

means for selecting one of said junctor groups to carry a communication signal, said means for selecting being responsive to said junctor occupancy; and

means for directing said communication signal through said one of said junctors in said selected one of said junctor groups in response to upstream and downstream signal traffic volume.