Patent ID: 8416681

Claim:
A network system comprising a first terminal, a second terminal, a first communication control apparatus for communicating with the first terminal, a second communication control apparatus for communicating with the second terminal, and a first network and a second network installed in parallel between the first communication control apparatus and the second communication control apparatus, the first communication control apparatus comprising: a first receiving processor for receiving a first SDH signal from the first terminal, a first arithmetic operator for conducting an error detecting arithmetic operation on a part of the first SDH signal to detect whether an error is included; and a packetizing processor for generating packetized data which includes at least a part of result information of the error detecting arithmetic operation, and the second communication control apparatus comprising: a depacketizing processor for converting the packetized data supplied from the first network to depacketized data; a second arithmetic operator for conducting an error detecting arithmetic operation on a part of the depacketized data and a part of depacketized data to be processed by the depacketizing processor next time to detect whether an error is included; and a switcher for switching control of a primary system and a backup system on the first network and the second network when an error has been detected by the error detecting arithmetic operation.