Distributed data processing in ring-structured networks architected for

Abstract

In a ring-structured data communication network, in which plural data processing systems exchange data and control information on a full duplex peer to peer basis, systems are presently architected to assign at least three I/O subchannels (i.e. at least three device addresses) to respective ring interface adapters. At least two of these subchannels are dedicated for providing separate input paths from the ring to at least two associated program-assignable areas in their system's main store, and a third of these subchannels is dedicated as an output path from the system's store to the ring. Collectively, these subchannels can sustain two input transfer processes and one output transfer process concurrently. One of these input processes is associatable with a locked mode of adapter operations which provides a non-blockable path for data transfer from a selected (remote) station on the ring to the respective system's main store. In this mode the other input subchannel and the output subchannel permit the system to maintain full duplex communication with other ring stations in respect to network transactions/processes which may require priority attention. Information is sent on the ring in discrete information frames of variable bit length, each frame acknowledged by a response frame. In general, response frames have much shorter bit lengths than the information frames, enabling the systems to access the ring more efficiently than they would be able to if response and information frames had equal lengths.