Local area network with fault detection and recovery
First Claim
1. In a local area network having (i) a token bus formed of redundant cables and (ii) a plurality of modules connected to the token bus, a method of detecting and recovering from faults comprising the steps of:
- with each module, periodically transmitting heartbeat signals on each redundant cable of the token bus at a predetermined periodic rate;
with each module, monitoring the periodic heartbeat signals on each redundant cable of the token bus, each module being adapted to receive on each of said cables every periodic heartbeat signal from other modules connected to the token bus;
indicating a fault when the heartbeat signals fail to be received at the predetermined periodic rate; and
initiating a fault recovery action.
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Accused Products
Abstract
A local area network having fault detection and recovery and a method for detecting and recovering from faults in a local area network are disclosed. The network has modules interconnected by a token bus implemented by a pair of redundant cable systems. All of the modules are agent modules and one of the modules also serves as a master module. Each agent module periodically transmits an agent heartbeat signal on each of its cables. Each module monitors all of the agent heartbeat signals from all of the other modules. When a fault is detected by a module, such as missed agent heartbeat signals from another module, the module applies agent rules to determine if and how the fault should be reported. The agent module reports the fault to the master module. The master module collects fault reports from the agent modules, applies a set of master rules to the agent fault reports, and generates a master failure report. The master module also initiates an appropriate network recovery action based upon the failure report generated. The master module periodically transmits a master heartbeat signal on the token bus which is received by the agent modules. The agent modules decode the master heartbeat signal to ensure that a master module is always present on the token bus.
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Citations
45 Claims
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1. In a local area network having (i) a token bus formed of redundant cables and (ii) a plurality of modules connected to the token bus, a method of detecting and recovering from faults comprising the steps of:
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with each module, periodically transmitting heartbeat signals on each redundant cable of the token bus at a predetermined periodic rate; with each module, monitoring the periodic heartbeat signals on each redundant cable of the token bus, each module being adapted to receive on each of said cables every periodic heartbeat signal from other modules connected to the token bus; indicating a fault when the heartbeat signals fail to be received at the predetermined periodic rate; and initiating a fault recovery action. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. In a local area network having (i) a token bus formed of redundant cables and (ii) a plurality of modules connected to the token bus, a method of detecting and recovering from faults comprising the steps of:
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nominating one of the modules to serve as a master module, all of the modules being agent modules; with each agent module, transmitting heartbeat signals on each redundant cable of the token bus at a predetermined periodic rate; with each agent module, monitoring the periodic heartbeat signals on each of said redundant cables, each agent module being adapted to receive on each of said cables every periodic heartbeat signal from all other agent modules connected to the token bus; with each agent module, determining when errors occur based on the monitored heartbeat signals; with each agent module, transmitting an error message to the master module when an error occurs; with the master module, monitoring the error messages received from the agent modules; with the master module, determining if a network fault exists based on the monitored error messages; and when a network fault is determined to exist, initiating a fault recovery action. - View Dependent Claims (23)
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24. A local area network with fault detection and recovery comprising:
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a plurality of modules; a token bus having redundant cables connecting the modules; in each module, at least one transmitter periodically transmitting heartbeat signals on each redundant cable of the token bus at a predetermined periodic rate; in each module, at least one receiver adapted to receive every heartbeat signal on each said cable from all other modules; and in each module, means for monitoring the periodic heartbeat signals on each said cable, said means for monitoring including means for indicating a fault when the heartbeat signals fail to be received at the predetermined periodic rate. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A token passing local area network with fault detection and recovery comprising:
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a master module on the network; at least one agent module on the network; a token bus with redundant cables for providing communication among the modules, said token bus interconnecting each agent module and the master module such that each module communicates with all other modules; in each module, at least one transmitter transmitting heartbeat signals on each redundant cable of the token bus at a predetermined periodic rate; in each module, at least one receiver being adapted to receive every heartbeat signal from the other modules on each redundant cable; in each module, means for monitoring the periodic heartbeat signals on each redundant cable; in each module, means for determining when an error occurs based on the monitored heartbeat signals; means for reporting an error to the master module when an error occurs; and in the master module, means for monitoring errors reported by modules and for determining when a network fault exists based on the monitored error reports; and means for initiating a fault recovery action.
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Specification