Double ring-type local area network system capable of switching transmission paths without interruption

摘要

In a ring-type network system including a plurality of nodes (A, B, C, D) connected by an L-ring and a R-ring, each of the nodes is constructed by a branch unit (A5, B5) for branching data to first and second directions, a first delay unit (A8, B8) for delaying the data in the first direction by a first delay time period (T1, T1'), a second delay unit (A9, B9) for delaying the data in the second direction by a second delay time period (T2, T2'), a first combiner (A2, B2) for inserting the delayed data in the first direction into a first time slot of a data frame on the L-ring, and a second combiner (A4, B4) for inserting the delayed data in the second direction into a first time slot of a data frame on the R-ring. Also, each of the nodes is constructed by a first distributor (A1, B1) for extracting data from a second time slot of a data frame on the L-ring, a second distributor (A3, B3) for extracting data from a second time slot of a data frame on the R-ring, a third delay unit (A11, B11) for delaying the data extracted by the first distributor by a third delay time period (T3, T3'), a fourth delay unit (A11, B11) for delaying the data extracted the second distributor by a third delay time period (T4, T4'), and a switching unit (A15, B15) for passing one of outputs of the third and fourth delay units.