An optical connecting system for connecting a first and a second optical device includes a first and a second multi-fiber device connector included in the first and second optical device and a multi-fiber optical connection cable including a plurality of optical fibers and having a first and a second multi-fiber cable connector at a first and second end thereof and being adapted to be connected to the first and second multi-fiber device connector. The optical devices are configured to transmit to and/or receive from the other optical device wanted optical data signals via optical fibers of the multi-optical fiber connection cable.

Provided is a multiplex transmission system capable of preventing occurrence of a mistake on connection of a client device to a multiplex transmission device. The multiplex transmission system includes: a detection means configured to detect new client connection that is new connection of a client device to a client port of each of a first multiplex transmission device 100 and a second multiplex transmission device 200; and a switch control unit 340 configured to control a switch unit 330 to connect a client port where new client connection is detected at a first time point in the first multiplex transmission device 100 with a client port where new client connection is detected at a second time point in the second multiplex transmission device, when a time interval between the first time point at which new client connection is detected in the first multiplex transmission device 100 and the second time point at which new client connection is detected in the second multiplex transmission device 200 is within a preset reference time, in a case where new client connection is detected in both the first multiplex transmission device 100 and the second multiplex transmission device 200.

A transmission device for which a work path is established in a first degree and a protection path is established in a second degree includes: a switch equipped with a plurality of optical ports; an optical signal generator, optically connected to a first optical port, and configured to generate an optical signal that is transmitted through the work path; and a monitor light generator, optically connected to a second optical port, and configured to generate monitor light by using a wavelength tunable light source. The monitor light generator controls a wavelength of the monitor light to be substantially the same as a wavelength of the optical signal. The switch guides the optical signal that arrives at the first optical port toward the first degree and guides the monitor light that arrives at the second optical port toward the second degree.

Systems and methods for monitoring an Optical Multiplex Section of a communication network are provided. A method, according to one implementation, includes the step of obtaining parameters related to optical signals traversing an Optical Multiplex Section (OMS) of a communication network. The OMS, in this example, includes multiple fiber spans defining a primary path and one or more protection paths. The method further includes the step of using the obtained parameters to determine a Signal-to-Noise Ratio (SNR) value associated with optical signals transmitted over the primary path. In response to determining that the SNR value falls below a predetermined threshold, the method includes the step of performing a switching action to enable transmission of optical signals over one of the one or more protection paths.

A transmission apparatus includes: a storage unit to store a table in which a wavelength terminated by each of transmission apparatuses is associated with each of the transmission apparatuses; a transmission unit to transmit a message including failure information to other transmission apparatus when a failure occurs; a switch controller to determine whether its own transmission apparatus is a last transmission apparatus that terminates the wavelength among transmission apparatuses that are present on a path up to a link where the failure, based on the table, when receiving the message from other transmission apparatus, and to perform a control of switching a transmission direction of a signal having the wavelength when the switch controller determines that its own transmission apparatus is the last transmission apparatus to terminate the wavelength; and a switch to switch a transmission direction of the signal for each wavelength under a control of the switch controller.