Fault-tolerant mastership arbitration in a multi-master system

• US 9,710,342 B1
• Filed: 12/23/2013
• Issued: 07/18/2017
• Est. Priority Date: 12/23/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Folkner, Nathan, Weinstein, Marvin, Bannon, Roy Michael
• Primary Examiner(s): Kasenge, Charles
• Application Number:
  US14/139,038
• Time in Patent Office: 1,303 Days
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/0421 Multiprocessor system
• CPC Class Codes: G05B 19/0426 Programming the control sequence
• CPC Class Codes: G05B 2219/21005 Several slave modules connected to same I-O of master, multiplexed by master
• CPC Class Codes: G05B 2219/2231 Master slave
• CPC Class Codes: G06F 11/2005 using redundant communication controllers
• CPC Class Codes: H04L 12/40176 involving redundancy error detection or correction of the data by redundancy in hardware using active fault-masking in interconnections G06F11/2002; error detection or correction of the data by redundancy in hardware using active fault-masking in storage systems using spares or by reconfiguring G06F11/2053

Abstract

A system and method are provided for controlling mastership among multiple devices in a fault tolerant manner. The devices may be configured to transmit and receive redundant heartbeat signals to indicate the mastership state of the device. The signals may operate in a plurality of configurations including active-master, ready and not-ready. By detecting the signal configuration sent from the other devices, each device is capable of managing its own transitions into and out of mastership in order to ensure that there is one and only one device functioning as master.

Claims

1. A method for controlling devices, comprising:

transmitting from a first device to a second device a first signal having a first frequency indicating a first device configuration, a second frequency indicating a second device configuration, or a third frequency indicating a third device configuration, wherein the first, second, and third frequencies are different from one another;

receiving at the first device from the second device a second signal having the first frequency indicating the first device configuration, the second frequency indicating the second device configuration, or the third frequency indicating the third device configuration, wherein;

the first device configuration is a configuration in which the device is controlling one or more other devices, the second device configuration is a configuration in which the device is not controlling the one or more other devices and is ready to control the one or more other devices, and the third device configuration is a configuration in which the device is not ready to control the one or more other devices;

taking control of the one or more other devices, by the first device, when the configuration indicated by the second signal changes from the first device configuration to either the second device configuration or the third device configuration; and

changing the first signal to indicate the first configuration.

2. The method of claim 1, wherein the first signal is transmitted while the second signal is received.

3. The method of claim 1, wherein the first signal comprises a set of at least two substantially similar first signals transmitted concurrently over a first and a second circuit respectively, the first circuit being different from the second circuit.

4. The method of claim 1, wherein transmitting the first signal and receiving the second signal are performed by an FPGA device.

5. The method of claim 1, wherein the first frequency is about 2 MHz, the second frequency is about 500 KHz, and the third frequency is about 0 Hz.

6. The method of claim 1, wherein each of the first and second devices are included in a separate network management card within the same chassis, and each of the first and second signals traverse a separate unidirectional electrical circuit through a backplane of the network switch or router.

7. The method of claim 1, wherein taking control of the one or more devices is based on a position value of the first device in a backplane when the first and second device are both controlling the one or more other devices.

8. A system for controlling devices, comprising:

an output component of a first device configured to output to an input component of a second device;

a first output signal indicating that the first device is controlling one or more other devices, a second output signal indicating that the first device is not controlling the one or more other devices and is ready to control the one or more other devices, and a third output signal indicating that the first device is not ready to control the one or more devices;

an input component of the first device configured to receive from an output component of the second device;

a first input signal indicating that the second device is controlling the one or more other devices, a second input signal indicating that the second device is not controlling the one or more other devices and is ready to control the one or more other devices, and a third input signal indicating that the second device is not ready to control the one or more other devices; and

circuitry configured to control the one or more other devices based at least in part on the detection of a change in a signal received at the input component of the first device, the change being from the first input signal to the second or third input signal,

wherein the first input signal and first output signal have a first frequency, the second input signal and the second output signal have a second frequency, the third input signal and third output signal have a third frequency, and the first, second, and third frequencies are different from one another.

9. The system of claim 8, wherein the output component of the first device is configured to output a signal at the same time the input component of the first device is receiving a signal.

10. The system of claim 8, wherein the first, second and third output signals each comprise a set of at least two substantially similar signals, each of the substantially similar signals being transmitted concurrently over a different circuit.

11. The system of claim 8, further comprising an FPGA device that includes the output component of the first device and the input component of the first device.

12. The system of claim 8, wherein the first frequency is about 2 MHz, the second frequency is about 500 KHz, and the third frequency is about 0 Hz.

13. The system of claim 8, wherein the first device comprises a management card and the one or more other devices are within a network switch or router.

14. The system of claim 8, wherein the output signals and the input signals traverse separate unidirectional electrical circuits through a backplane of a network switch or router.

15. A system of controlling mastership comprising:

a first management device comprising a first input component and a first output component, the first output component configured to output to a second input component three mastership signals and the first input component configured to receive from a second output component the three mastership signals, wherein the three mastership signals indicate an active configuration, a ready configuration, and a not ready configuration, respectively, and the each of the three mastership signals has a different pulse frequency than the other two mastership signals;

a second management device comprising the second input component and the second output component, the second output component configured to output to the first input component the three mastership signals and the second input component configured to receive from the first output component the three mastership signals;

a first communication link between the first output component and the second input component; and

a second communication link between the first input component and the second output component.

16. The system of claim 15, wherein the first and second management devices output the three mastership signals along the first and second communication links, wherein the first output component outputs one of the three mastership signals at the same time the first input component is receiving one of the three mastership signals.

17. The system of claim 15, wherein the first management device includes an FPGA device that includes the first output component and the first input component.

18. The system of claim 15, wherein the active configuration corresponds to a mastership signal with a frequency of about 2 MHz, the ready configuration corresponds to a mastership signal with a frequency of about 500 KHz and the not ready configuration corresponds to a mastership signal with a frequency of about 0 Hz.

19. The system of claim 15, wherein the first and second management devices are within the same chassis.

20. The system of claim 15, wherein each of the first and second communication links is a separate unidirectional electrical circuit through a backplane of a network switch or router.