An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.

One embodiment of the present invention provides an optical link coupling two nodes in an optical transport network. The optical link includes a fiber span, which includes a first optical fiber, a second optical fiber, and a splitter. The input of the splitter is coupled to an input of the fiber span, and first and second outputs of the splitter are coupled, respectively, to the first and second optical fibers. The optical link further includes a first amplifier coupled to the first optical fiber, a second amplifier coupled to the second optical fiber, and an optical switch. Two inputs of the optical switch are coupled to outputs of the first and second amplifiers, respectively; and an output of the optical switch is coupled to an input of a third amplifier.

A network capable of being used in a datacenter is described. In some embodiments, the network can comprise a set of optical fiber rings, wherein each optical fiber ring carries data traffic on one or more wavelengths, and wherein each optical fiber ring is partitioned into multiple sectors. A reconfigurable optical add-drop multiplexer (ROADM) can be coupled to at least one optical fiber in each of at least two sectors. An electro-optical-switch can be coupled to each ROADM in each of the at least two sectors. A set of switches can be coupled to each electro-optical-switch in each of the at least two sectors. The set of switches can comprise a first layer of aggregation switches that is coupled to a second layer of edge switches, wherein the edge switches can be coupled to servers in a datacenter.

Optical protection switching apparatus (10), for a single fibre bidirectional WDM optical ring, comprising: first (12) and second (14) ports for coupling to first and second adjacent portions of a single fibre bidirectional WDM optical ring; an optical splitter (16) comprising an input to receive a WDM aggregate optical signal, and first and second outputs coupled to the first and second ports; an optical switch (108) between the second output and the second port; and processing circuitry (24) to receive at least one of an indication of transmission continuity in the optical ring and an indication of transmission discontinuity in the optical ring, and to generate a switch control signal (20) comprising instructions to cause the optical switch to be open when there is transmission continuity in the optical ring and to cause the optical switch to be closed when there is transmission discontinuity in the optical ring.

An optical switch configuration is disclosed that gives the appearance of a logical cut in a fiber optic line. The inputs to the optical switch are redundant so that if a fiber event occurs on one input, the optical switch can switch to the other input. In the case where both paths of an optical fiber have fiber events, router convergence is delayed. One mechanism to mitigate a prolonged fiber degradation is to dampen the optical power on the output optical fiber of the optical switch, such that it creates a loss of light and appears as a clean cut of the optical fiber. Another solution uses optical switches to inject an alternate light source onto the output optical fiber, wherein the alternate light source is of a wavelength to be filtered out giving an appearance of a clean cut of the optical fiber.

Optical protection switching apparatus (10), for a single fibre bidirectional WDM optical ring, comprising: first (12) and second (14) ports for coupling to first and second adjacent portions of a single fibre bidirectional WDM optical ring; an optical splitter (16) comprising an input to receive a WDM aggregate optical signal, and first and second outputs coupled to the first and second ports; an optical switch (108) between the second output and the second port; and processing circuitry (24) to receive at least one of an indication of transmission continuity in the optical ring and an indication of transmission discontinuity in the optical ring, and to generate a switch control signal (20) comprising instructions to cause the optical switch to be open when there is transmission continuity in the optical ring and to cause the optical switch to be closed when there is transmission discontinuity in the optical ring.

An optical switch configuration is disclosed that gives the appearance of a logical cut in a fiber optic line. The inputs to the optical switch are redundant so that if a fiber event occurs on one input, the optical switch can switch to the other input. In the case where both paths of an optical fiber have fiber events, router convergence is delayed. One mechanism to mitigate a prolonged fiber degradation is to dampen the optical power on the output optical fiber of the optical switch, such that it creates a loss of light and appears as a clean cut of the optical fiber. Another solution uses optical switches to inject an alternate light source onto the output optical fiber, wherein the alternate light source is of a wavelength to be filtered out giving an appearance of a clean cut of the optical fiber.

An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.

An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.

An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.