Abstract: Apparatus and method for routing messages in a communications network having a plurality of communications stations interconnected by a plurality of communication links, and having at least one destination station. Each communications station informs each neighboring communications station of the distance between itself and the destination station. Each communications station stores information identifying a first neighboring station through which it has a primary path to the destination station. The primary path is the shortest of all possible paths to the destination station. Each communications station that is connected to the destination station by at least one alternate path stores information identifying a second neighboring station through which it has an alternate path to the destination station.

Abstract: The computing machine includes an array of programmable elements programmably interconnected to implement networks of algebraic functions. Each element provides a sufficient set of logic primatives in the algebra that may be a Boolean algebra. The elements and the interelement wiring support the communications requirements of large classes of problems and preferably of all problems. The algebraic transform machine offers highly concurrent operation but avoids many of the programming difficulties of existing concurrent systems. The machine is regular in structure; it extends to large size and capability, and operates at high speed. In one embodiment, the machine consists of a grid of segments and each segment holds the value (true or false) of a Boolean variable. Crossing segments do not connect directly but the value on one wire segment can effect the value on another. The effect of one segment on another is programmable.

Abstract: A hierarchy of landmarks is established for the nodes in the network. Each node is assigned at least one hierarchy level designation and has a corresponding radius. An address is assigned to each of the nodes, the address including components representing landmarks wherein each landmark represented by the address component is within the radius of the landmark represented by the next lower address component. Each node maintains a routing table for routing entries to landmarks within the radii of which a node resides. A source node chooses a path toward the highest level landmark represented by the address components of a destination node until the path reaches a node within the radius of the landmark represented by the next lower level address component. This procedure is repeated for the remaining address components.

Abstract: The present access protocol for contention networks results in synchronous network operation. Each node determines the next transmission instant by counting from the beginning of the most recently received packet of information a time equal to that packet's labeled length minus the previously measured round trip propagation delay seen by the node. Subsequent instants will occur at intervals equal to the maximum propagation delay allowed on the network. Each time a subsequent packet is received, synchronization is rederived based on the packet. If no packets are received within predetermined slots, the network is considered to be in asynchronous mode, with transmissions allowed at any time following the next slot. The disclosed packet synchronized multiple access (PSMA) protocol improves the performance measures by which local area networks are evaluated.