Transmission path fault detection system for token ring - employs composite fault search frame with IEEE 802.5 standard portion and annex contg. address of origin

摘要

Each fault detector (e.g. 10b) associated with stations (13) joined by outer and inner rings (11,12) incorporates a microprocessor (20), a memory (21) and two MAC-level controllers (23a,23b) and physical-level controllers (24a,24b) for the respective rings. A relay controller (25) causes the relay (26) to interconnect the rings when a fault is detected by means of a fault search frame, which may extend to about 4000 bytes between start and finish limiters. A second frame includes data identifying its source. ADVANTAGE - Less significant faults can be detected reliably by transmission and reception of fault search of any length.