Monitoring redundant control buses to provide a high availability local area network for a telecommunications device

• US 6,425,009 B1
• Filed: 06/08/1999
• Issued: 07/23/2002
• Est. Priority Date: 06/08/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Parrish, Brent K., McCracken, Ronald A., Fernald, John J.
• Primary Examiner(s): Lim, Krisna
• Application Number:
  US09/328,038
• Time in Patent Office: 1,141 Days
• Field of Search: 370/219, 370/216, 370/217, 370/221, 370/245, 370/364, 370/438, 370/257, 709/224
• US Class Current: 709/224
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 41/0681 Configuration of triggering conditions
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

A telecommunications device includes a local area network with redundant first and second buses. Multiple cards coupled to the first and second buses communicate using the first bus. A first monitor coupled to the first and second buses detects a failure of the first bus and communicates a message indicating the failure using a data network. A second monitor also coupled to the first and second buses may detect the failure of the first bus and may also communicate a message indicating the failure using the data network. The first monitor and the second monitor may receive the messages from one another and cause the cards to communicate using the second bus. In a more particular embodiment, the second monitor transmits a test signal using the first bus in response to the message from the first monitor.

Claims

1. A telecommunications device, comprising:

a local area network comprising redundant first and second control buses operable to communicate control data;

a plurality of cards coupled to the first and second control buses, the cards operable to communicate control data using the first control bus;

a data network operable to communicate non-control telecommunications data between the cards;

a first monitor coupled to the first and second control buses and to the data network, the first monitor operable to detect a failure of the first control bus and to communicate a message indicating the failure using the data network;

a second monitor coupled to the first and second control buses and to the data network, the second monitor operable to detect the failure of the first control bus and to communicate a message indicating the failure using the data network; and

the first monitor operable to receive the message from the second monitor and the second monitor operable to receive the message from the first monitor, the monitors operable to cause the cards to communicate control data using the second control bus in response to the messages.

2. The device of claim 1, wherein the device comprises a switching unit having a high availability backplane environment.

3. The device of claim 1, wherein the second monitor is operable to transmit a test signal using the first control bus in response to the message from the first monitor if the second monitor has not detected the failure of the first control bus.

4. The device of claim 3, wherein the second monitor is operable to communicate the message to the first monitor in response to an improper test signal result.

5. The device of claim 3, wherein the device is operable to isolate the first monitor in response to a proper test signal result.

6. The device of claim 1, wherein the first monitor comprises first selection logic for the first control bus and second selection logic for the second control bus, the first selection logic having a first value and the second selection logic having a second value during operation of the device, the first monitor operable to drive the second value to the first value in response to the message from the second monitor.

7. The device of claim 6, further comprising a selection bus coupled to the cards, to the first selection logic, and to the second selection logic, the selection bus indicating to the cards to communicate using the second control bus in response to the second value being driven to the first value.

8. The device of claim 6, wherein the second monitor comprises first selection logic for the first control bus and second selection logic for the second control bus, the first selection logic for the second monitor having the first value and the second selection logic for the second monitor having the second value, the second monitor operable to drive the second value of its second selection logic to the first value, the device operable to isolate the second monitor if the first monitor does not also drive the second value of its second selection logic to the first value.

9. The device of claim 1, wherein:

the first monitor comprises first selection logic for the first control bus having a first value and second selection logic for the second control bus having a second value, the first and second values determining a selection state; and

each of the plurality of cards is operable to detect an invalid transition from the selection state.

10. A monitor for monitoring a local area network in a telecommunications device comprising a plurality of cards coupled to one another using a data network operable to communicate non-control telecommunications data between the cards, the local area network comprising redundant first and second control buses coupling the cards, the cards operable to communicate using the first control bus, the monitor operable to:

receive a message from a second monitor communicated using the data network and indicating a failure of the first control bus;

if the monitor has detected the failure, communicating a message to the second monitor using the data network to indicate the failure; and

if the monitor has not detected the failure,

transmitting a test signal using the first control bus in response to the message from the second monitor, and

detecting a test signal result.

11. The monitor of claim 10, wherein the device comprises a switching unit having a high availability backplane environment.

12. The monitor of claim 10, wherein the monitor is operable to communicate a message to the second monitor using the data network to indicate the failure if the test signal result is an improper test signal result.

13. The monitor of claim 10, wherein the monitor is operable to cause the second monitor to be isolated if the test signal result is a proper test signal result.

14. A method of monitoring a local area network in a telecommunications device comprising a plurality of cards coupled to one another using a data network operable to communicate non-control telecommunications data between the cards, the local area network comprising redundant first and second control buses coupling the cards, the method comprising:

communicating between cards using the first control bus;

detecting a failure of the first control bus using a first monitor;

communicating a first message from the first monitor to a second monitor using the data network to indicate the failure;

receiving the first message at the second monitor;

if the second monitor has detected the failure, communicating a second message from the second monitor to the first monitor using the data network to indicate the failure;

receiving the second message at the first monitor; and

causing the cards to communicate using the second control bus in response to the first and second messages.

15. The method of claim 14, wherein the device comprises a switching unit having a high availability backplane environment.

16. The method of claim 14, further comprising, if the second monitor has not detected the failure, transmitting a test signal from the second monitor using the first control bus in response to the first message.

17. The method of claim 16, further comprising:

detecting an improper test signal result; and

communicating the second message from the second monitor to the first monitor to indicate the failure in response to the improper test signal result.

18. The method of claim 16, further comprising:

detecting a proper test signal result; and

isolating the first monitor in response to the proper test signal result.

19. The method of claim 14, further comprising:

driving first selection logic in the first monitor and corresponding to the first control bus from a first value to a second value in response to the second message; and

driving second selection logic in the first monitor and corresponding to the second control bus from the second value to the first value in response to the second message.

20. The method of claim 19, further comprising, in response to the second value being driven to the first value and using a selection bus that is coupled to the cards, to the first selection logic, and to the second selection logic, indicating to the cards to communicate using the second control bus.

21. The method of claim 19, further comprising isolating the first monitor in response to driving the second selection logic from the second value to the first value if second selection logic in the second monitor and corresponding to the second control bus is not also driven from the second value to the first value.

22. The method of claim 14, further comprising:

determining a selection state at the first monitor, the selection state determined according to a first value that is associated with first selection logic for the first control bus and a second value that is associated with second selection logic for the second control bus;

transitioning from the selection state at the first monitor; and

detecting, at each of the plurality of cards, an invalid transition from the selection state.