A passive signal transport medium, constructed as an array of spectral-temporal connectors, connects a large number of access nodes to a number of distributors to form a single-hop network of wide coverage and high throughput yet simplified control. Parameterized spectral-temporal connectors define network expansion over networks using conventional signal transport media. A network accommodating 32000 access nodes with a throughput of an Exabits/second is realizable. The distributors may be geographically distributed (the access nodes are naturally geographically distributed). The entire network structure is parameterized. Selecting the number of distributors to equal the number of access nodes, and pairing each access node with a respective distributor to form an integrated node, an expanded fully-meshed network is realized with each pair of integrated nodes having a direct path and numerous single-hop paths. Several routing schemes within the fully-meshed network are considered to enable both global control and distributed control.

An optical transmission apparatus (1_1) according to the present invention includes a first transmission unit (11_1) that transmits a first optical transmission signal (21_1), a second transmission unit (11_2) that transmits a second optical transmission signal (21_2), and an output unit that outputs, when the first optical transmission signal (21_1) and the second optical transmission signal (21_2) share a set of information, both the first optical transmission signal (21_1) and the second optical transmission signal (21_2) to a first path (26_1) and outputs, when the first optical transmission signal (21_1) and the second optical transmission signal (21_2) do not share the set of information, one of the first optical transmission signal (21_1) and the second optical transmission signal (21_2) to a second path (26_2).

A wavelength cross-connect device (20A) performs relay processing, the relay processing being such that wavelength multiplexed signal lights (1a to 1m), which are multiband transmitted from a plurality of routes M(1), are demultiplexed into different wavelength bands (S band, C band, and L band), and for each route, respective optical signals of the different wavelength bands (S band, C band, and L band) are amplified, then subject to rout change by WSSs and outputted to output side routes M(2). The device includes C-band WXC units 22 that are the same in total number as the wavelength bands of the optical signals of the respective wavelength bands and perform relay processing on optical signals of a specific wavelength band (C band) of the different wavelength bands. The device includes input side conversion units (31,32) provided on the input side of the C-band WXC units 22 for converting optical signals of wavelength bands other than the specific wavelength band into optical signals of the specific wavelength band. The device includes output side conversion units (35,36) provided on the output side for converting the optical signals of the specific wavelength band converted on the input side into the before-conversion optical signal. It is configured that the optical signals of the specific wavelength band directly input from the input side are directly output after the relay processing by the C-band WXC units.

A network system for a data center is described in which a switch fabric may provide full mesh interconnectivity such that any servers may communicate packet data to any other of the servers using any of a number of parallel data paths. Moreover, according to the techniques described herein, edge-positioned access nodes, optical permutation devices and core switches of the switch fabric may be configured and arranged in a way such that the parallel data paths provide single L2/L3 hop, full mesh interconnections between any pairwise combination of the access nodes, even in massive data centers having tens of thousands of servers. The plurality of optical permutation devices permute communications across the optical ports based on wavelength so as to provide, in some cases, full-mesh optical connectivity between edge-facing ports and core-facing ports.

A network system for a data center is described in which a switch fabric provides interconnectivity such that any servers may communicate packet data to any other of the servers using any of a number of parallel data paths. Moreover, according to the techniques described herein, edge-positioned access nodes, permutation devices and core switches of the switch fabric may be configured and arranged in a way such that the parallel data paths provide single L2/L3 hop, full mesh interconnections between any pairwise combination of the access nodes, even in massive data centers having tens of thousands of servers. The access nodes may be arranged within access node groups, and permutation devices may be used within the access node groups to spray packets across the access node groups prior to injection within the switch fabric, thereby increasing the fanout and scalability of the network system.

In order to readily carry out communication between terminal stations, a submarine optical communication system includes a first terminal station including a first monitoring means for monitoring the signal quality of dummy light a first dummy light source that outputs dummy light to the second terminal station, and a first light transmitting means for transmitting an optical signal to the second terminal station, the optical signal including a first signal quality of the dummy light; and the second terminal station including a second dummy light source that outputs dummy light to the first monitoring means, a second monitoring means for monitoring the signal quality of the dummy light, and a light receiving means for receiving the optical signal.

A method of assigning performance indicators to objects of a network employing a computation to assign performance indicators to said objects of said network such that a sum of said performance indicators of objects along a given path in said network in relation to a first threshold value indicates whether said path fulfils a predetermined criterion, and/or indicates whether said path does not fulfil said predetermined criterion.

A method of evaluating a performance of a path in a network based on the performance indicators involves the steps of calculating a sum of performance indicators for said objects along said path and evaluating a performance of said path by comparing said sum against a first threshold value.

An optical transmission apparatus includes a first transmitter configured to transmit a first optical signal in a first wavelength band and a second optical signal in a second wavelength band located next to the first wavelength band; a second transmitter configured to transmit a third optical signal in a third wavelength band located next to the second wavelength band and a fourth optical signal in a fourth wavelength band located next to the third wavelength band; and a processor coupled to the first transmitter and the second transmitter and configured to select the third wavelength band among the first wavelength band, the second wavelength band, the third wavelength band and the fourth wavelength band, and control the first wavelength band, the second wavelength band, and the fourth wavelength band based on the third wavelength band.

An optical transmission device includes: a selector configured to select a wavelength of a signal to be transmitted to an optical transmission line and output a wavelength-multiplexed signal; an adjustor configured to control a power level of the wavelength-multiplexed signal; and a controller configured to control the adjustor or the selector, wherein the selector selects a wavelength of an optical signal in a second wavelength band different from an existing first wavelength band, and when the second wavelength band is added to or removed from the optical transmission line, the controller controls power of the wavelength-multiplexed signal in the second wavelength band at a slower speed than power control in the first wavelength band.

A method for constructing an AWG based non-blocking optical multicast switching network, comprising constructing a non-blocking optical copy network via a wavelength replication module and an arrayed waveguide grating recursively and constructing a non-blocking optical multicast switching network via cascading a data copy network with a point-to-point switching network. The number of active optical devices required for constructing an N×N optical switching network with r input/output ports and with each port carrying m wavelengths is just O(N log.sub.m N), realizing system scalability and saving hardware cost and power consumption. By splitting the routing path of the multicast network into a routing path with O(1) complexity in the copy network and a routing path in a point-to-point unicast switching network, the routing complexity of the multicast switching network is equivalent to that of a unicast switching network.