Patent ID: 7738507

Claim:
A network relay device that carries out data transmission to and from an opposite device, the network relay device comprising: multiple ports connecting with corresponding multiple ports of the opposite device via multiple-physical lines; and a link aggregation control module that aggregates the multiple physical lines to establish a link aggregation, which is regarded as one logic link, and carries out transmission of a control frame signal including a synchronization bit, as well as data transmission, at each port via the physical lines, in response to detection of occurrence of a trouble in communication of at least one of the aggregated multiple physical lines, the link aggregation control module causing all ports that connect with a normal physical line without the trouble among the multiple ports to stop the data transmission and send the control frame signal including the synchronization bit set equal to a first value, where the first value functions to stop the data transmission at corresponding ports of the opposite device connecting with the normal physical lines.