Method of purging erroneous signals from closed ring data communication

Abstract

A method of initializing non-synchronous peer-to-peer data communication rings, and for effecting error recovery in such networks. On detection of error, each station operates in a purging configuration to clear the ring. In the purging configuration the station's receiving circuits are isolated and its transmitting circuits transmit 'clear' signals containing this station's own address as destination. These signals serve to purge all potentially erroneous information in all upstream stations which then are operationally connected to that station. If a loss condition is persistent the station operates first in a 'bypass' configuration for a third predetermined time interval, then in the purging configuration for the second time interval, and then resumes normal operation. In the bypass configuration the station's ring input is connected directly to its output and the (locally clocked) output of its transmitting circuits is connected to the input of its receiving circuits. This serves to restore reception clocking in temporary alignment with the local transmission clock source. When a station switches from purging mode to normal operation it resumes monitoring its reception synchronism. If is fails to develop synchronism it repeats the foregoing recovery procedure.