JPS6252973B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a loop optical communication system. One type of computer network is a loop network (hereinafter referred to as a loop). As shown in Figure 1, the loop consists of multiple stations S and CS (CS is a control station) connected in a loop by optical fiber cables or coaxial cables,
It is composed of computers C attached to each station. The advantages of loops are: a. Low cost. b. The interface is simple. c Highly expandable. However, there are problems with reliability. That is, even a single failure on the loop including the station can impair the functionality of the entire loop. As a countermeasure, (1) In case of a station failure, a bypass route as shown in Figure 2 will be provided to separate the station with the failure from the loop. (2) In case of line failure, prepare a working loop 1 and a reverse backup loop 2 as shown in Figure 3.
The station S also has a loopback function. As shown in FIG. 4, when a line failure 3 occurs, loopback is performed between the working loop 1 and the protection loop 2 to create a new loop. That is what is being considered. However, since the loopback method uses two loops, there is a big problem in terms of cost, which is an advantage of loops. An object of the present invention is to provide a low-cost and highly reliable loop optical communication system. In the present invention, a plurality of stations S and CS are connected in a loop by one optical fiber cable 10, as shown in FIG. Light with wavelength λ ₁ is communicated counterclockwise on this optical fiber cable 10, and this wavelength λ ₁ loop is used as a conventional hair loop. In addition, optical fiber cable 10
Light of wavelength λ ₂ communicates clockwise above the top, and this wavelength λ
₂ loops are used as backup loops. In this case, the wavelength λ ₂ loop does not necessarily need to be in a standby state, and can be used for normal communication. FIG. 6 shows two stations 20 , 30 . Each station includes optical couplers C1, C2, transmitters T1, T2, transmitters R1, R2, and switch SW.
1, SW2, SW3 and a logic section L. During normal operation, the wavelength λ ₁ loop 40 connects the optical coupler C1→
It is connected to the optical fiber cable 10 via the receiver R1→logic section L→switch SW3→transmitter T1→optical coupler C2. Also, the wavelength λ ₂ loops 50
are connected to the fiber cable 10 in the order of C2→R2→L→SW2→T2→C1. Note that the switch SW1 is opened during normal operation. FIG. 7 shows the new loop that is formed in the event of a line failure. When a line fault 60 occurs, the station 2 adjacent to the fault location
The loopback function of 0 and 30 operates. That is, switch SW1 is closed. As a result, at the station 20 , C1→R1→L→
The signal is looped back along the route SW3→SW1→T2→C1. Also, at station 30 , C2→R2
→ Turn back the signal along the route of L → SW2 → SW1 → T1 → C2. That is, when station 20 receives a signal with wavelength λ ₁ , it transmits a signal with wavelength λ ₂ , and station 30 receives a signal with wavelength λ ₂ and transmits a signal with wavelength λ ₁ . In this way, the wavelength λ
A new loop containing a mixture of _{λ 1} and λ ₂ is formed. As described above, according to the present invention, a low-cost and highly reliable loop optical communication system can be realized.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams for explaining the prior art, Figure 5 is a diagram for explaining the present invention, Figure 6 is a diagram showing an embodiment of the present invention, and Figure 7 is a diagram for explaining line failure. FIG. 3 is a diagram for explaining the operation of an embodiment of the present invention at a time. 10... Optical fiber cable, 20 , 30 ... Station, C1, C2... Optical coupler, T1, T2...
Transmitter, R1, R2...Receiver, SW1, SW2,
SW3...Switch, L...Logic section.

Claims (1)

[Claims] 1. In an optical communication system in which multiple stations are connected in a loop by a single optical fiber cable, optical signals with wavelengths λ ₁ and λ ₂ communicate in opposite directions on the optical fiber, resulting in a line failure. In such a case, the stations on both sides of the fault point receive an optical signal of the wavelength and send it back using the optical signal of the other wavelength, forming a new loop path in which wavelengths λ ₁ and λ ₂ are mixed. A loop-type optical communication system.