JPS6031131B2 - distributed optical network - Google Patents

Description

[Detailed description of the invention] This invention relates to distributed optical networks.

FIG. 1 shows a packet switching system in a distributed optical network. The sending node N divides the message sent from the sending host into pieces of one fixed length, adds a header, an error control code, etc., and uses the message as a unit of information transmission (referred to as a packet).
The packet is sent from the sending node N to the receiving node N5 through an appropriate route, taking into account the congestion of the transmission path. After confirming that there are no errors, the receiving node N5 corrects the order of the packets, reproduces the message, and sends it to the receiving host N5. In the packet switching method, packets are transmitted from node to node one after another by selecting empty wires, so it has the advantages of high line efficiency and resistance to cable failures. On the other hand, there are problems with routing (what route to take) and because it is an accumulation exchange, there are drawbacks such as slow transfer speed. Figure 2 shows a loop network.

The loop consists of a plurality of stations connected in a loop through one cable LI and a computer attached to each station. Its features include: ■Low cost. ■Easy interface. ■Extensible. ■No routine required. ■Since it is not an accumulation exchange, the transfer speed is fast. The drawback is that reliability is a problem. i.e. 1 on the loop containing the station
Even a failure in just one place can be fatal. The present invention provides a new distributed optical network that combines the features of the packet switching method and loop network described above, and a wavelength division multiplexing transmission method.

The configuration of one embodiment of the present invention is shown in FIG.

As can be seen in the figure, this network is composed of multiple loop networks. The transmission line is an optical fiber cable. Each loop is differentiated by wavelength and has a control station for each loop. The control station has the function of closing the loop and providing a clock to the bus, and operates only on predetermined wavelengths. For other wavelengths, it becomes a station. Each station has an optical coupler, an optical demultiplexer, an optical receiver, a logic function section, a decoder, an optical multiplexer, etc., as described later, and can individually receive optical signals of multiple wavelengths, and can receive optical signals of any wavelength. can output optical signals to any route. These functions allow you to construct any loop network. The network in Figure 3 has a wavelength input. It consists of four loops:

^． Loop is station S, → S2 → S4 → S5 (control station) → S, Input 2 loop is S2
→S3 (control station) →S7 →S6 →S
4 → S2, enter 3 Loop is S4 → S5 → S6 (control station) → S4, ~ Loop is S, → S2 →
S3 (control station) → S4 → S5 → S.
A wave-wheel multiplexed optical signal passes through a transmission line with overlapping loops. The configuration of a station to enable the network of the present invention will be explained using S4 as an example.

Four optical fibers, A to D, are connected to S4 (Fig. 4), and input 2 is received from A and transmitted to D, and input 2 is sent to C.
It receives input 3 from C and sends it to D, receives input 4 from B and sends it to D. Figure 5 shows the configuration of the station. Transmission lines A to D are connected to a directional coupler. A method coupler 11 is inserted in order to use the transmission line in both directions. Input signals of the station are combined by an optical coupler 12 and distributed for each wavelength by an optical demultiplexer 13. The distributed optical signals are subjected to optical-to-electrical conversion by the corresponding optical receivers 14 and output to the logic function section 15. The signals passed through the logic function 15 (which are not received by this station) are input to the decoder 16. This decoder 6 allows each signal to be returned to its original wavelength and output to an arbitrary transmission path. decoder 6
It is the control signal that controls the. The signal distributed by the decoder is electrically-optically converted by an optical transmitter 17 of a selected wavelength and inserted into a transmission line via an optical multiplexer 18 and a directional coupler 11. Each station has the above functions, and by controlling these functions as a whole,
Loops can be constructed for any path at any wavelength. The arrows in FIG. 5 indicate the signal flow of S4. For example, when transmitting to stations S and S6 (FIG. 3), it is first determined whether a loop including stations S and S6 is formed. In this example, there is no such loop, so next station S,
A common station is found between the loop having station S6 and the loop having station S6. The loop of Ima-in has stations S, and S5, while the loop of ^3 has stations S5 and S6, so station S5
is determined as a relay point. Then, in the loop of ^, it is transmitted from station S, to S5, and at station S5, it is input,
The signal of the loop may be transferred to the loop of input 3 and transmitted to station S6 via the loop of input 3. Note that the formed loop can form a new loop after a suitable period of time (for example, one month). FIG. 6 shows another embodiment of the invention.

It is assumed that each station is arranged in the same manner as in FIG. However, since no loop is formed in this example, no control station is required, and the functions of each station are simplified. An example of the configuration of each station is shown in FIG. The difference from FIG. 5 is that optical demultiplexers 71, 72, 73, and 74 are provided for each transmission line without using an optical coupler. In FIG. 6, station S,
When transmitting from station S, to S6, station S,
Outputs a signal as shown in the figure.

That is, it provides information indicating which stations to pass before the data to be transmitted. In this example, station S has decided to use the route S2→S3→S4→S6. Such a decision is made by selecting an arbitrary route based on the connection status of each station.
The relaying stations S2, S3, and S4 can select and transmit wavelengths that are not used in the transmission lines connected to the respective stations. The features of the present invention are as follows.

1. A distributed network can be constructed from multiple loops.

2. Since any transmission path can be selected, faults and failed stations can be isolated from the transmission path.

(Improved reliability) 3. Transfer speed is slow because it is not an accumulation exchange.

4. Communication volume can be increased by wavelength multiplexing.

5 Routing becomes easier after determining the loop route.

6. Buses can be used efficiently by combining loops.

[Brief Description of the Drawings] Figures 1 and 2 are diagrams showing the prior art, Figure 3 is a diagram showing an embodiment of the present invention, and Figures 4 and 5 are diagrams depicting an embodiment of the present invention. FIG. 6 is a diagram for explaining another embodiment of the present invention, and FIGS. 7 and 8 are diagrams for explaining other embodiments of the present invention. S,,S2,. ．． ．． S6. ．． ．．・．． ．． Station, C
S input, CS input 2, ..., CS input 4...Control station for each loop. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. In a distributed optical network in which a plurality of stations are connected by optical fiber cables, each station receives light of different wavelengths supplied via the plurality of optical fiber cables connected to this station. A distributed optical network characterized by having the function of receiving individual signals and the function of transmitting optical signals of any wavelength to any optical fiber cable. 2. A patent characterized in that each station has the function of transmitting an optical signal of a predetermined wavelength to a predetermined optical fiber cable, and multiple wavelength multiplexing loops are formed between the stations. A distributed optical network according to claim 1.