the control of the transmission of useful optical signals on different line paths of an optical transmission device is accomplished via at least one of the following features : using signal sources and signal sinks , the useful optical signals are coupled into the line paths , or are coupled out of them ; at least one portion of the optical line paths is configured as normal line paths having coupling nodes via which a switchover to an alternative line path can be undertaken if a normal line path is disturbed ; in addition to the useful optical signals , test signals , whose evaluation is used for the switchover between the line paths , are transmitted bidirectionally section - by - section ; at least two types of test signals can be transmitted , of which a first type is used as an indicator for an intact line path and a second type as an indicator for a disturbed line path ; and any switchover to an alternative line path is only undertaken if , before the detection of the disturbance , a test signal of the first type has been transmitted on the normal line path . a decentralized switchover of the line paths is provided and pointless switchovers , which do not lead to any improvements in the transmission , can be avoided .