BigPatents India

The present invention is concerned with highly available communication networks, in particular for industrial or utility applications such as substation automation. The devices are connected to two redundant lines (la, lb) through two independent transceivers (2a, 2b) and bus controllers (3a, 3b), i.e. the physical layer and the link layer of the corresponding protocol stack is duplicated. For seamless operation, a sender (11) sends frames (100a, 100b) simultaneously over both lines and a receiver (13) accepts whichever frame of a pair comes first and ignores the late frame. The invention describes a method for discarding duplicate frames at the link layer without considering the higher protocol layers, based on a counter (202, 203) inserted in the frame and an algorithm for rejection, with a corresponding means to detect which frames operate according to the redundancy protocol. Fig.l Redundancy ID for rejection of duplicate frames in redundant Ethernet-type networks