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 method resolves cliques formed in a network comprising a plurality of nodes that are communicatively coupled to one another over at least a first channel. The method comprises, at each node, wherein that node is a member of a current clique: listening asynchronously for data on the first channel from a first neighbor's neighbor node of that node. The method further comprises, at that node, when a first valid frame is received on the first channel from the first neighbor's neighbor node of that node, listening asynchronously for a second valid frame on the first channel from a first neighbor node of that 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 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: A Byzantine filter tester including a feedback loop, a pseudo random waveform generator and an output tester. The feedback loop is coupled between an output of a device under test and an input of the device under test. The feedback loop includes an odd number of inversions that create oscillations and an integrator with a very large time constant for filtering the oscillations to determine an input threshold of the device under test. The pseudo random waveform generator provides waveforms to the input of the device under test to cover test points in a logic grid defined in part by the determined input threshold of the device under test. Finally, the output tester monitors a plurality of redundant outputs of the device under test to verify the proof coverage of the device under test.

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: 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, 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 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: 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: 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: A stream cipher cryptosystem includes a keystream generator receiving a key and providing a keystream. A cryptographic combiner combines a first binary data sequence and the keystream with two non-associative operations to provide a second binary data sequence. In encryption operations, the cryptographic combiner is an encryption combiner and the first binary data sequence is a plaintext binary data sequence and the second binary data sequence is a ciphertext binary data sequence. In decryption operations, the cryptographic combiner is a decryption combiner and the first binary data sequence is a ciphertext binary data sequence and the second binary data sequence is a plaintext binary data sequence.

Abstract: A stream cipher cryptosystem includes a pseudo-random bit generator receiving a key and providing a vulnerable keystream vulnerable to crytanalysis, and a non-linear filter cryptographic isolator to convert the vulnerable keystream into a protected keystream. The non-linear filter cryptographic isolator includes a multiplier for performing a multiplication function on the vulnerable keystream to provide a lower partial product array and an upper partial product array, and a simple unbiased operation (SUO) for combining the lower partial product array and the upper partial product array to provide the protected keystream. In example encryption operations, a plaintext binary data sequence is combined with the protected keystream to provide a ciphertext binary data sequence. In example decryption operations, a ciphertext binary data sequence is combined with the protected keystream to provide a plaintext binary data sequence.

Abstract: A fast pseudo-random number generator, which can be employed in a variety of systems such as a stream cipher cryptosystem or a Monte Carlo simulation system, includes a linear feedback shift register (LFSR) having a state contained in N storage elements storing N bits of binary data which are separated into w words having word length M. At least two tap sources provide binary data, each tap source has a number of bits which is a multiple of M. The LFSR also includes a linear feedback function coupled to tap sources and providing a temporary value which is a linear function, such as bit-wise exclusive-or, of the binary data provided from the tap sources. The LFSR state is advanced by shifting the binary data in the storage elements by a multiple of M bits and provide the temporary value to fill in storage elements that would otherwise be empty from the shifting.

Abstract: A stream cipher cryptosystem includes a pseudo-random number generator receiving a key and providing a keystream. A cryptographic combiner combines a first binary data sequence and the keystream with a one's complement operation to provide a second binary data sequence. In encryption operations, the cryptographic combiner is an encryption combiner and the first binary data sequence is a plaintext binary data sequence and the second binary data sequence is a ciphertext binary data sequence. In decryption operations, the cryptographic combiner is a decryption combiner and the first binary data sequence is a ciphertext binary data sequence and the second binary data sequence is a plaintext binary data sequence.

Abstract: A communication protocol and hardware is provided which allows a meshed network to reliably perform in a real-time environment. The protocol establishes that within specified regions of a mesh, a single node will transmit on that region at any given time. The transmitted message is propagated to all other nodes in the region by flooding the network. Immediately upon receiving each bit of data, a receiving node will immediately retransmit that bit, thereby increasing the speed of the flooding. Arbitration and lockout logic is provided which assures that nodes receiving data from multiple sources will be able to correctly handle and retransmit that data.

Abstract: The present invention provides a method for transmitting large data messages over networks. In one embodimen□□t, this is accomplished by partitioning the large data message into smaller packets. The packets are transmitted over the network in reverse sequential order, from the last created packet to the first created packet. Either the transmitter or the receiver attaches the packet control information to the packets. Immediately after each packet is transmitted and received by at least one receiver, it is written into a memory pre-allocated memory location. Subsequently transmitted and received packets e written into locations adjacent previously written packets, however, they are shifted in position such that a portion of the packet overwrites the packet control information that was attached to the previously written packet. This is repeated until all of the packets have been transmitted and written and the large data message reintegrated and coherent.

Abstract: An apparatus and method for transmitting information between dual redundant components comprises two information sources each of which is coupled to two transmitters, the outputs of which are coupled to four signal paths for transmission to two independent voters. Each of the voters compares predetermined pairs of the signals on the four signal paths and provides a preferred one of the signals to a corresponding receiver based on the results of the pair comparisons.