Abstract: In one embodiment, a node comprises an interface to communicatively couple the node to a channel. The channel communicatively couples the node to a first neighbor node and a first neighbor's neighbor node in a first direction. When the node relays relayed data along the channel, the node compares data received from the first neighbor node with data received from the first neighbor's neighbor node. The relayed data comprises: at least one of: the data received from the first neighbor node and the data received from the first neighbor's neighbor node; and information indicative of the results of the comparison.

Abstract: In one embodiment, a method is performed at a node. The method comprises outputting, from a rate-changeable clock included at the node, a first clock signal having a clock rate. The method further comprises generating a second clock signal from the first clock signal for use in determining when transmissions in a network are to start. The method further comprises sending and receiving data from the node using the first clock signal as a line encoding/decoding clock. The method further comprises making relative clock-rate measurements at the node based on transmissions received at the node and using the relative clock-rate measurements to adjust the clock rate of the rate-changeable clock. The method further comprises making clock-state adjustments to the second clock signal.

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 special node is used in a distributed time-triggered cluster. The special node comprises protocol functionality to establish a time base to use in communicating with a plurality of end nodes and to source timing-related frames to the plurality of end nodes in accordance with the distributed time-triggered communication protocol. The protocol functionality establishes the time base without regard to any timing-related frame sourced from any of the plurality of end nodes. In one embodiment, the protocol functionality of the special node is implemented in a low complexity manner. In one embodiment, the cluster comprises a star topology and the special node performs at least one of semantic filtering and rate enforcement. In another embodiment, the cluster comprises a bus or peer-to-peer topology and each end node is coupled to the communication channel using a low-complexity special local bus guardian.

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: In one embodiment, a node comprises an interface to communicatively couple the node to a plurality of independent communication links. The node changes the mode in which the node operates when the node receives an indicator on a plurality of the independent communication links.

Abstract: In one embodiment, a node comprises an interface to communicatively couple the node to a channel. The channel communicatively couples the node to a first neighbor node and first neighbor's neighbor node in a first direction. When the first neighbor node is scheduled to transmit and the node receives data from the first neighbor node via the channel, the node forwards the data to the first neighbor's neighbor, receives other data from the first neighbor's neighbor, compares the data to the other data, and relays the data along the channel with information indicative of the comparison.

Abstract: Systems and methods for network clock synchronization are provided. In one embodiment, a method for clock synchronization in a braided ring network comprises: providing a schedule for a braided ring network comprising a plurality of nodes, wherein at least two nodes comprise a self-checking pair of a first node and a second node, the first node performing a method comprising: determining when a first rendezvous message is received from the second node; when the second rendezvous message is received, calculating a time difference between the send instance of the first rendezvous message and a local time; when the time difference is not greater than a reference bound, calculating a sending point for transmitting a synchronization message, wherein the sending point is calculated based on the time difference; and selectively sending the synchronization message to the braided ring network when the sending point is reached based on the time difference.

Abstract: In one embodiment, a system comprises a plurality of nodes that are communicatively coupled to one another. Each of the plurality of nodes, in the absence of any faults, is communicatively coupled to at least a first neighbor node and a first neighbor's neighbor node and a second neighbor node and a second neighbor's neighbor node. When at least a first clique and a second clique exist within the plurality of nodes and a first node included in the first clique successfully receives a synchronization message associated with the second clique from the first neighbor node of the first node and the first neighbor's neighbor node of the first node, the first node does the following. The first node defects to the second clique and synchronizes to the synchronization message. The first node also communicates a join message to at least the second neighbor node of the first node and the second neighbor's neighbor node of the first node.

Abstract: In one embodiment, one or more self checking pairs are implemented at the application layer in a network that supports the qualified propagation of data at the transport layer (for example, in a network having a braided ring topology).

Abstract: A network comprises a plurality of nodes; a plurality of bi-directional point-to-point communication links, wherein a priority-based arbitration scheme is used to communicate over each of the plurality of point-to-point links; and a hub that is communicatively coupled to each of the plurality of nodes via the plurality of point-to-point links; wherein when the hub determines that one or more of the nodes is transmitting a message via the hub, the hub selects 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 to the other nodes with elevated priority.

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: A half-duplex communication network comprises a plurality of communication links, each link being configured a priori to communicate in one direction; and a plurality of nodes, each node coupled to a first and second direct neighbor nodes and a first and second skip neighbor nodes via the plurality of communication links. Each node comprises propagation logic adapted to arbitrate conflicts between concurrent messages based on at least one of higher level policies and a comparison between a priority of each message, wherein each node is adapted to communicate a message without waiting to determine if another node is transmitting another message with a higher priority.

Abstract: In one embodiment, a method of processing a received unit of data received at a node comprises using a first key to determine if at least a portion of the received unit of data was encrypted using a key that is compatible with the first key. The method further comprises determining whether to take a fault-containment action based on at least in part whether at least a portion of the received unit of data was encrypted using a key that is compatible with the first key. The method further comprises, when at least some of the received unit of data is relayed to the second node, using a second key to encrypt at least a portion of the received unit of data that is relayed to the second node in order to generate an encrypted version of the received unit of data that is relayed. The first key differs from the second key.

Abstract: In one embodiment, a method is performed at a node. The method comprises outputting, from a rate-changeable clock included at the node, a first clock signal having a clock rate. The method further comprises generating a second clock signal from the first clock signal for use in determining when transmissions in a network are to start. The method further comprises sending and receiving data from the node using the first clock signal as a line encoding/decoding clock. The method further comprises making relative clock-rate measurements at the node based on transmissions received at the node and using the relative clock-rate measurements to adjust the clock rate of the rate-changeable clock. The method further comprises making clock-state adjustments to the second clock signal.

Abstract: In one embodiment, a network comprises a plurality of nodes that are communicatively coupled to one another using bidirectional, half-duplex links. The network has a logical first channel over which data is propagated along the network in a first direction and a logical second channel over which data is propagated along the network in a second direction. For a given period of time, at least one of the plurality of nodes is scheduled to be a transmitting node that transmits data on both the first channel and the second channel. A first subset of the nodes not scheduled to transmit during the period are scheduled to relay data received from the first channel along the first channel. A second subset of the nodes not scheduled to transmit during the period are scheduled to relay data received from the second channel along the second channel.

Abstract: In one embodiment, one or more self checking pairs are implemented at the application layer in a network that supports the qualified propagation of data at the transport layer (for example, in a network having a braided ring topology).

Abstract: In one embodiment, a node comprises an interface to communicatively couple the node to a first channel. The first channel communicatively couples the node to a first neighbor node and a first neighbor's neighbor node in a first direction. When the node is operating in an unsynchronized mode: the node relays, along the first channel, for a relay period, data received from the first neighbor node that was sourced from that first neighbor node and, after relaying the data received from the first neighbor node that was sourced from that first neighbor node and for a block period, the node blocks data received from the first neighbor while the node relays, along the first channel, data received from the first neighbor's neighbor node.

Abstract: In one embodiment, a node comprises an interface to communicatively couple the node to a channel. The channel communicatively couples the node to a first neighbor node and a first neighbor's neighbor node in a first direction. When the node relays relayed data along the channel, the node compares data received from the first neighbor node with data received from the first neighbor's neighbor node. The relayed data comprises: at least one of: the data received from the first neighbor node and the data received from the first neighbor's neighbor node; and information indicative of the results of the comparison.

Abstract: A method for authenticating a message in a time division multiple access network is provided. The method includes receiving a message from an active relaying component, inspecting a value in the message inserted by the active relaying component, and comparing the value with an expected value based on a transmission schedule.