Techniques and solutions are described for providing high-availability computing resources to service client requests. Groups of computing nodes are organized into loops, a given loop being configured to execute a particular subset of tasks, such as tasks with a hash value in a particular ranged serviced by a loop. Computing nodes within a loop can evaluate a task request to determine whether the task request conflicts with another task currently assigned to a node. If a computing node which sent out a task request determines that no conflict was identified, it can execute the task request. Communications within a loop can occur unidirectionally, such that a node which initiated a communication will receive the communication from the last loop node. Loops can be connected to form a ribbon, the ribbon providing a namespace for task execution, where hash ranges for the namespace are uniquely assigned to loops of the ribbon.

In order to enable more stable monitoring of communication status, a communication device is provided with: a setting unit which sets a first wavelength selected from wavelength selection alternatives included in wavelengths of light included in dummy light, and a first transmission power which is selected in accordance with a first communication status from a plurality of transmission power selection alternatives that are set in advance; a generation unit which generates light of the first wavelength from the dummy light; an adjustment unit which adjusts the light of the first wavelength to first light of the first transmission power; and a multiplexing unit which multiplexes the first light with communication light serving as light for a predetermined communication so as not to overlap each other on the time axis, and which delivers the multiplexed light to another communication device.

In order to enable more stable monitoring of communication status, a communication device is provided with: a setting unit which sets a first wavelength selected from wavelength selection alternatives included in wavelengths of light included in dummy light, and a first transmission power which is selected in accordance with a first communication status from a plurality of transmission power selection alternatives that are set in advance; a generation unit which generates light of the first wavelength from the dummy light; an adjustment unit which adjusts the light of the first wavelength to first light of the first transmission power; and a multiplexing unit which multiplexes the first light with communication light serving as light for a predetermined communication so as not to overlap each other on the time axis, and which delivers the multiplexed light to another communication device.

A master unit configured to manage a plurality of remote units connected in a ring topology, the master unit comprising: a network management section configured to transmit at least one of a path-state monitoring control signal and a delay measurement control signal to the plurality of remote units in a first direction and a second direction which is a reverse direction of the first direction, and receives an acknowledgement signal in response to the at least one of a path-state monitoring control signal and a delay measurement control signal; and switching control means for transmitting a forward signal received from a base station in the first direction, and transmitting a switching control signal in the second direction when a defect is detected in any remote unit among the plurality of remote units by the network management section.

A master unit configured to manage a plurality of remote units connected in a ring topology, the master unit comprising: a network management section configured to transmit at least one of a path-state monitoring control signal and a delay measurement control signal to the plurality of remote units in a first direction and a second direction which is a reverse direction of the first direction, and receives an acknowledgement signal in response to the at least one of a path-state monitoring control signal and a delay measurement control signal; and switching control means for transmitting a forward signal received from a base station in the first direction, and transmitting a switching control signal in the second direction when a defect is detected in any remote unit among the plurality of remote units by the network management section.

A fiber optic drop terminal assembly includes a housing, a spool and a fiber optic distribution cable. The housing has a first exterior surface and an oppositely disposed second exterior surface. A plurality of ruggedized adapters is mounted on the first exterior surface of the housing. The ruggedized adapters include a first port accessible from outside the housing and a second port accessible from inside the housing. The spool is engaged with the second exterior surface and includes a drum portion. The fiber distribution cable is coiled around the drum portion. The distribution cable includes a first end and an oppositely disposed second end. The second end is disposed inside the housing.

A fiber optic drop terminal assembly includes a housing, a spool and a fiber optic distribution cable. The housing has a first exterior surface and an oppositely disposed second exterior surface. A plurality of ruggedized adapters is mounted on the first exterior surface of the housing. The ruggedized adapters include a first port accessible from outside the housing and a second port accessible from inside the housing. The spool is engaged with the second exterior surface and includes a drum portion. The fiber distribution cable is coiled around the drum portion. The distribution cable includes a first end and an oppositely disposed second end. The second end is disposed inside the housing.

In a multi-layer network, a control load in the upper layer network increases, and the usage efficiency and the reliability of the entire network decrease; therefore, a multi-layer network system according to an exemplary aspect of the present invention includes a first network manager configured to set a logical path in a first network layer; and a second network manager configured to set a physical path corresponding to the logical path, in a second network layer, wherein the second network manager includes a network information storage configured to store physical network information including physical route information and transmission characteristic information on the second network layer, and the first network manager sets the logical path based on the physical network information.

In a multi-layer network, a control load in the upper layer network increases, and the usage efficiency and the reliability of the entire network decrease; therefore, a multi-layer network system according to an exemplary aspect of the present invention includes a first network manager configured to set a logical path in a first network layer; and a second network manager configured to set a physical path corresponding to the logical path, in a second network layer, wherein the second network manager includes a network information storage configured to store physical network information including physical route information and transmission characteristic information on the second network layer, and the first network manager sets the logical path based on the physical network information.

Systems and methods are disclosed herein for coherently modulating and demodulating coherent optical signals using 5-bit constellations. The 5-bit constellations have improved suitability for short reach optical communications systems. A first 5-bit constellation can be formed from four rings. The first and fourth rings can form quadrature phase-shift keyed four-symbol sub-constellations, and the second and third rings can form phase-shift keyed twelve symbol constellations. Symbols from the third and fourth sub-constellations are arranged to form a square. A second 5-bit constellation can include an inner 16 symbol sub-constellation and an sixteen symbol outer sub-constellation. Each of the symbols of the inner sub-constellation are equally spaced from its nearest neighboring symbols along both the quadrature and in-phase axes. Each of the symbols in the outer constellation has an equal euclidean-distance with its nearest neighboring symbols in the outer sub-constellation.