Abstract: A cabling system that provides continuous transport of data, as well as testing. At all times a channel is available for data transmission. In one embodiment, the cabling system includes a cable in turn including two data transmission channels. First and second transceivers are provided at respective opposite ends of the cable connected to the data transmission channels. At least one of the transceivers is functionally capable of both a data transmission mode and a test or audit mode, and periodically alternates between two operational modes. In another embodiment, first and second transceivers are provided at respective opposite ends of the cable and connected to a data transmission channel. At least one of the transceivers is functionally capable of both data transmission employing one wavelength and testing or auditing employing another wavelength.