Abstract: In some examples, a device includes a receiver configured to receive a first message and receive a second message after receiving the first message, the first and second messages including first and second elements of a hash chain, respectively. The device also includes processing circuitry configured to apply a hash function to the second element of a hash chain to generate a hashed element and determine that the hashed element matches the first element in the hash chain. The processing circuitry is also configured to determine that the second message was received within an acceptable time window and determine that the second message is authentic in response to determining that the hashed element matches the first element in the hash chain and determining that the second message was received within the acceptable time window.

Abstract: A method comprises transmitting a plurality of copies of a message from each of a first transmission node and a second transmission node, each copy having a respective identification and forwarding each of the plurality of copies of the message among other nodes in the network based, at least in part, on the respective identification of each copy such that each copy of the message traverses a predetermined communication path among the other nodes. A respective first received copy is compared to a respective second received copy at each of the other nodes. The integrity of the respective first and second copies is validated at each of the other nodes if the copies match and the copies traversed disjoint communication paths.

Abstract: A method of communicating data in a network comprises receiving a copy of a message on a first channel via at least one of a first port and a second port, the first port coupled to a first neighbor node and the second port coupled to a first neighbor's neighbor node; and selecting either the copy of the message received via the first port or the copy of the message received via the second port if a copy of the message is received via both the first port and the second port. If a copy of the message is only received via one of the first port or the second port, the received copy of the message is selected.

Abstract: A network comprises a plurality of nodes; and a plurality of links communicatively coupling each of the plurality of nodes to at least one respective adjacent node of the plurality of nodes via a first communication channel and to another respective adjacent node of the plurality of nodes via a second communication channel. At least one of the plurality of nodes is a source node configured to source data. The source node is configured to form a virtual self-checking pair with one of the respective adjacent node on the first communication channel or the respective adjacent node on the second communication channel to achieve a consistent broadcast of data on the first and second communication channels. Data exchanged between the source node and the respective adjacent node in the virtual self-checking pair is only sourced by the source node.

Abstract: One embodiment comprises a network that includes a plurality of bi-directional links and a plurality of nodes. Each node is communicatively coupled to two neighbor nodes and to two skip nodes using the plurality of bi-directional links. Three neighboring nodes of the plurality of nodes form a triple modular redundant (TMR) set having a first end node, a second end node, and a center node, the first end node configured to transmit output data in a first direction and the second end node configured to transmit output data in a second direction.

Abstract: A communication network comprises a communication medium and a plurality of nodes. Each node is configured to communicate with the other nodes using a protocol that has at least one of an idle period or a preamble period. The at least one node of the plurality of nodes is configured to transmit an out-of-band signal during at least one of the idle period or the preamble period and is configured to modify at least a portion of the out-of-band signal to communicate data to at least one other node. The at least one other node is configured to interpret the modified portion of the out-of-band signal to identify the data communicated in the modified out-of-band signal. The modified out-of-band signal complies with the protocol's encoding rules such that any node not configured to interpret the modified portion of the out-of-band signal processes the modified out-of-band signal according to the protocol.

Abstract: A system comprises a plurality of nodes; and a hub that is communicatively coupled to each of the plurality of nodes via a plurality of point-to-point links, wherein a priority-based arbitration scheme is used by the plurality of nodes and the hub to communicate over each of the plurality of point-to-point links. When the hub determines that one or more of the plurality of nodes is each transmitting a message having an identification field comprising a first sub-field and a second sub-field, the hub uses the first sub-field to select which node's message should be forwarded to the other nodes based, at least in part, on the priority-based arbitration scheme and forwards the selected node's message as it is received to the other nodes, continuing with the second sub-field of the selected node's message.

Abstract: A method comprises transmitting a plurality of copies of a message from each of a first transmission node and a second transmission node, each copy having a respective identification and forwarding each of the plurality of copies of the message among other nodes in the network based, at least in part, on the respective identification of each copy such that each copy of the message traverses a predetermined communication path among the other nodes. A respective first received copy is compared to a respective second received copy at each of the other nodes. The integrity of the respective first and second copies is validated at each of the other nodes if the copies match and the copies traversed disjoint communication paths.

Abstract: A communication network comprises a communication medium and a plurality of nodes. Each node is configured to communicate with the other nodes using a protocol that has at least one of an idle period or a preamble period. The at least one node of the plurality of nodes is configured to transmit an out-of-band signal during at least one of the idle period or the preamble period and is configured to modify at least a portion of the out-of-band signal to communicate data to at least one other node. The at least one other node is configured to interpret the modified portion of the out-of-band signal to identify the data communicated in the modified out-of-band signal. The modified out-of-band signal complies with the protocol's encoding rules such that any node not configured to interpret the modified portion of the out-of-band signal processes the modified out-of-band signal according to the protocol.

Abstract: A method of communicating data in a network comprises receiving a copy of a message on a first channel via at least one of a first port and a second port, the first port coupled to a first neighbor node and the second port coupled to a first neighbor's neighbor node; and selecting either the copy of the message received via the first port or the copy of the message received via the second port if a copy of the message is received via both the first port and the second port. If a copy of the message is only received via one of the first port or the second port, the received copy of the message is selected.

Abstract: A cluster comprises a plurality of end nodes that communicate with one another over at least one communication channel. Each end node is assigned a time slot for transmission of frames; wherein each node comprises a local guardian configured to prevent transmission of timing-related frames sourced from the respective end node. The cluster also comprises a special node that communicates with the plurality of end nodes, wherein the special node establishes a time base and sources timing-related frames to the plurality of end nodes. The transmission schedule includes at least one common scrubbing time slot during which each of the plurality of end nodes is configured to generate a timing-related frame. The special node is configured to determine if the local guardian in any of the plurality of nodes failed to prevent transmission of the respective generated timing-related frame during the common scrubbing time slot.

Abstract: A network comprises a plurality of nodes; and a plurality of links communicatively coupling each of the plurality of nodes to at least one respective adjacent node of the plurality of nodes via a first communication channel and to another respective adjacent node of the plurality of nodes via a second communication channel. At least one of the plurality of nodes is a source node configured to source data. The source node is configured to form a virtual self-checking pair with one of the respective adjacent node on the first communication channel or the respective adjacent node on the second communication channel to achieve a consistent broadcast of data on the first and second communication channels. Data exchanged between the source node and the respective adjacent node in the virtual self-checking pair is only sourced by the source node.

Abstract: One embodiment includes a method that includes receiving an ephemeral value from a challenging device. The method also includes retrieving data whose content is presumed known to the challenging device. The method includes generating a digital signature of the data based on the ephemeral value. Additionally, the method includes transmitting the digital signature to the challenging device.

Abstract: A method of configuring a node comprises receiving a first message having a count field value from a first direct link; receiving a second message having a count field value from a first skip link; adjusting the count field value in the first message by a first adjustment amount; adjusting the count field value in the second message by a second adjustment amount; comparing the adjusted count field value in the first message with the adjusted count field value in the second message; if the adjusted count field value in the first message matches the adjusted count field value in the second message, using the adjusted count field value in the first message to determine a node identity for the node; and processing subsequent messages based on the node identity.

Abstract: A cluster comprises a plurality of end nodes that communicate with one another over at least one communication channel. Each end node is assigned a time slot for transmission of frames; wherein each node comprises a local guardian configured to prevent transmission of timing-related frames sourced from the respective end node. The cluster also comprises a special node that communicates with the plurality of end nodes, wherein the special node establishes a time base and sources timing-related frames to the plurality of end nodes. The transmission schedule includes at least one common scrubbing time slot during which each of the plurality of end nodes is configured to generate a timing-related frame. The special node is configured to determine if the local guardian in any of the plurality of nodes failed to prevent transmission of the respective generated timing-related frame during the common scrubbing time slot.

Abstract: A communication device comprises a port via which the communication device is operable to communicate over a communication channel; command hardware operable to output a controlled signal over the communication channel; monitor hardware operable to monitor the controlled signal and output a controlling signal to block propagation of the controlled signal if a fault is identified in the controlled signal; and signal blocking circuitry coupled to a transmission path of the controlled signal and to a transmission path of the controlling signal; wherein, when the controlled signal is to be blocked, the signal blocking circuitry applies the controlling signal to the controlled signal such that a receiver at one end of the transmission path of the controlled signal identifies the controlled signal as a faulty signal; and wherein, when the controlled signal is not being blocked, the controlled signal is unimpeded by the signal blocking circuitry.

Abstract: A communication device comprises first and second circuits to implement a plurality of ports via which the communicative device is operable to communicate over a plurality of communication channels. For each of the plurality of ports, the communication device comprises: command hardware that includes a first transmitter to transmit data over a respective one of the plurality of channels and a first receiver to receive data from the respective one of the plurality of channels; and monitor hardware that includes a second receiver coupled to the first transmitter and a third receiver coupled to the respective one of the plurality of channels. The first circuit comprises the command hardware for a first subset of the plurality of ports. The second circuit comprises the monitor hardware for the first subset of the plurality of ports and the command hardware for a second subset of the plurality of ports.

Abstract: A distributed control system comprises a first network section comprising one or more control nodes containing control logic operable to perform control function computations; a second network section, wherein the second network section comprises; a plurality of additional nodes responsive to the one or more control nodes in the first network section, each of the plurality of additional nodes communicatively coupled to two neighbor nodes and to two skip nodes using a plurality of links; first and second gateway interfaces each coupled to the first and second network sections and each operable to interface the first network section to the second network section; wherein the first network section is operable to communicate signals using a first communication protocol; and wherein the plurality of nodes in the second network section are operable to communicate signals over the plurality of links using a second communication protocol that is different from the first communication protocol.

Abstract: A method of communicating node status in a star network comprising a hub and a plurality of nodes comprises sending a first message to the hub from a first node included in the plurality of nodes; forwarding the first message from the hub to at least one second node included in the plurality of nodes; communicating status information to the hub from the at least one second node after receiving at least a portion of the first message at the at least one second node; compiling a status vector based on the status information received from each of the at least one second nodes; and sending the status vector from the hub to at least the first node.

Abstract: System and methods for initializing secure communications with lightweight devices are described herein. In one embodiment, the method includes enabling a device manager to securely communicate with a lightweight device, the method comprising receiving encrypted data from the device manager, wherein the device manager received the encrypted data from the lightweight device. In the embodiment, the method also includes decrypting the encrypted data to produce access information, wherein the access information enables the device manager to securely communicate with the lightweight device. In the embodiment, the method also includes securely transmitting the access information to the device manager.