Method and apparatus for redundancy switching in line cards

• US 20020179720A1
• Filed: 03/12/2002
• Published: 12/05/2002
• Est. Priority Date: 05/30/2001
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Liva, Valentino, Wingfield, Isaac
• Granted Patent: US 7,003,690 B2
• Time in Patent Office: Days
• US Class Current: 235/492
• CPC Class Codes: H04M 3/005 Interface circuits for subscriber lines current supply H04M19/00 and subgroups; supervisory, monitoring or testing arrangements H04M3/22 and subgroups; in key telephone systems H04M9/006
• CPC Class Codes: H04M 3/08 Indicating faults in circuits or apparatus

Abstract

A system for redundancy switching of line cards in a communications system. When a line card needs to be replaced or serviced or becomes inoperable, signal traffic is switched to and through a redundant line card. This is achieved by implementing a switching fabric on I/O cards, the I/O cards carrying signal traffic to and from line cards. The switching fabric enables traffic to and from and I/O card servicing the line card to be replaced to instead service the redundant line card.

Claims

1. A system for redundancy switching of M primary line cards of a communications system, each of said primary line cards coupled to a corresponding primary I/O card, said system comprising:

a switching fabric coupled to said primary I/O cards;

N additional I/O cards coupled to said switching fabric; and

N redundant line cards, each said redundant line card coupled to a corresponding one of said additional I/O cards, further wherein if any of said primary line cards is not operational, one of said redundant line cards is then coupled to the primary I/O card corresponding to said non-operational primary line card and said non-operational primary line card is de-coupled from its corresponding primary I/O card.

2. An apparatus according to claim 1 wherein upstream and downstream traffic destined for and originating from said non-operational primary line card is re-routed from and through said redundant line card coupled to said primary I/O card corresponding to said non-operational primary line card.

3. An apparatus according to claim 2 wherein said switching fabric comprises a plurality of switching devices.

4. An apparatus according to claim 3 wherein switching devices on said primary I/O card corresponding to said non-operational primary line card change state when redundancy switching is desired, and further wherein said switching devices on said additional I/O card corresponding to said redundant line card also change state when redundancy switching is desired.

5. An apparatus according to claim 4 wherein the change of state of said switching devices on said primary I/O card cause decoupling of said non-operational primary line card from said primary I/O card and coupling of said primary I/O card with said redundant line card.

6. An apparatus according to claim 4 wherein the change of state of said switching devices on said additional I/O card cause decoupling of said redundant line card from said additional I/O card and coupling of said primary I/O card with said redundant line card via said additional I/O card.

7. A system according to claim 1 wherein M is equal to N.

8. A system according to claim 1 wherein N equals one.

9. A system according to claim 1 wherein M is not equal to N.

10. A system according to claim 3 wherein said switching devices are solid-state RF switches.

11. A system according to claim 2 wherein each said primary I/O card includes a plurality of upstream connectors to carry upstream traffic and plurality of downstream connectors to carry downstream traffic.

12. A system according to claim 2 wherein each said additional I/O card includes a plurality of upstream connectors to carry upstream traffic and plurality of downstream connectors to carry downstream traffic, said upstream and downstream connectors not connected any live signal path.

13. A system according to claim 1 wherein said coupling of said redundant line card with said primary I/O card is achieved over a Back-up bus, said Back-up bus interconnecting all said primary I/O cards and additional I/O cards.

14. A system according to claim 13 wherein said Back-up Bus comprises a series of traces through a midplane.

15. A system according to claim 14 wherein said midplane is utilized to couple each primary line card to its corresponding primary I/O card.

16. A system according to claim 14 wherein said midplane is utilized to couple each redundant line card to its corresponding additional I/O card.

17. A system according to claim 1 wherein primary I/O cards are coupled to additional I/O cards via card-to-card jumpers.

18. A system according to claim 1 further comprising a midplane, said midplane utilized to couple each primary line card to its corresponding primary I/O card and to couple each additional I/O card to its corresponding redundant I/O card.

19. A system according to claim 18 wherein an array of pins of a connector connecting said primary I/O card to said primary line card is configured to simulate a coaxial cable.

20. A system according to claim 19 wherein said array includes a three by three array of pins, the center pin carrying an active signal and the other eight pins configured to provide grounding and shielding for said center pin.

21. A method of redundancy switching of a primary line card in a communications system, said primary line card coupled to a corresponding I/O card, said method comprising:

enabling upstream traffic to said primary line card and downstream traffic from said primary line card when said primary line card is operable;

disabling upstream traffic to said primary line card and downstream traffic from said primary line card when said primary line card is inoperable; and

if said primary line card is inoperable, then enabling upstream traffic to said redundant line card and downstream traffic from said redundant line card.

22. A method according to claim 21 further comprising:

disabling upstream traffic to said redundant line card and downstream traffic from said redundant line card when said primary line card is operable.

23. A method according to claim 22 wherein all said enabling and disabling are achieved via switching configured on said I/O card.

24. A method according to claim 23 wherein enabling upstream traffic to said primary line card includes:

coupling said primary line card to said I/O card.

25. A method according to claim 23 wherein enabling downstream traffic from said primary line card includes:

coupling said primary line card to said I/O card.

26. A method according to claim 23 wherein disabling upstream traffic to said primary line card includes:

de-coupling said primary line card to said I/O card.

27. A method according to claim 23 wherein disabling downstream traffic from said primary line card includes:

de-coupling said primary line card to said I/O card.

28. A method according to claim 23 wherein enabling upstream traffic to said redundant line card includes:

coupling said redundant line card to said I/O card.

29. A method according to claim 23 wherein enabling downstream traffic from said redundant line card includes:

coupling said redundant line card to said I/O card.