Abstract: An interconnect topology providing enhanced fault tolerance to a multi-component data processing system. The topology utilizes a plurality of rings for interconnecting multiple system components, or cards, at least two of which are indirectly connected so that communication therebetween is through a third component. Each of the system components is coupled to a set of at least two different rings and includes interface circuits for routing data and a bridge for permitting data to be transferred between the at least two rings.

Abstract: A system for controlling access and transmission timing of communication in a repeating sequence over a network between nodes of one or more terminals, such as in a local area network. Each node in the network is equipped to recognize the presence of boundaries in the transmissions of messages by all nodes in the network. Each node is assigned a place in the list of all the nodes on the network and is controlled by a local timing system to be able to transmit over the network only after the node next preceding it in the list has transmitted. This recognition is accomplished by counting the message boundaries on the network and comparing the count against the list of nodes in the network. Each node will transmit during its time a message of variable length, up to a maximum, but never less than a minimum that identifies its presence in the network.