JPH01115230A - Optical fiber communication lan - Google Patents

Abstract

PURPOSE:To simplify system of the title LAN and to lower its costs by cascade- connecting >=3 nodes including a starting point and a termination by means of a single optical fiber, and using an optical signal with different wavelengths in the rising direction and falling direction of a circuit. CONSTITUTION:A node 1 of the starting point, intermediate nodes 2, 3..., and termination node N are cascade-connected by a single optical fiber, and thus, a loop is formed. The optical signal of a wavelength lambda1 is used for the falling direction and the optical signal of a wavelength lambda2 is used for the rising direction. At the input/output terminal of each node, a demultiplexer/multiplexer WDM of light is provided. The optical signal is demultiplexed into the wavelengths lambda1 and lambda2 at an input terminal, a processing such as a demodulation, a modulation, and an amplification is performed, the optical signals lambda1 and lambda2 are multiplexed at an output terminal, and are sent to the next node. When a line is troubled, for example, at an (a) point, they are looped back at the adjoining nodes 2 and 3. Thus, the line constitution is simplified, and the costs are lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to an optical fiber communication LAN in which the outbound and return routes are constructed of the same transmission path.

Conventional technology In general, loop networks represented by LAN etc.
As shown in FIG. 3, nodes are installed along the outer periphery, and each node is connected in cascade using, for example, an optical fiber. If the starting point of the loop is node l, the final node N is connected to node l. Normally, it is configured with a one-way loop, but a loop is formed using a loopback function as a protection in the event of a failure (indicated by point a).

When constructing a loop network by installing multiple nodes on a route connecting a starting point and an ending point, such as on a railway or road, an optical fiber is connected from the starting point, node 1, to the ending point, node N, as shown in Figure 4. Connect in cascade to form an outbound route. In FIG. 4, it is assumed that the intervals between each node are equal to L. on the other hand,
The return route connects the end point node N to the start point node L, but the distance between the start point and the end point is a long distance (several 1010-100k
In this case, a repeater will be required in the middle.

Problems to be Solved by the Invention In the above configuration, four optical fibers are required because the outbound and return routes are the same, and in addition, multiple repeaters are required for the connection between the destination node and the source node. is necessary.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a transmission system that allows a loop network to be realized using a single optical fiber.

Means for Solving the Problems The present invention connects each node on the path connecting the starting point and the ending point in cascade using optical fibers, and transmits the wavelength λl from the ending point to the starting point for the outward transmission from the starting point to the ending point. The wavelength λ2 is used for transmission on the forward and return routes, and a loop is constructed by bidirectional wavelength multiplexing transmission.

Effects According to the present invention, the above-mentioned configuration makes it possible to share the outgoing and incoming transmission paths.

Example An embodiment of the present invention will be described with reference to FIG.

A starting point 1 and an ending point N are located in a straight line, and a plurality of nodes are installed on the line, and the nodes are connected in cascade through optical fibers. Each node has an optical transmitter (Elo), an optical receiver (0/E), and an optical multiplexer/demultiplexer (
A loop network can be constructed by transmitting data using a wavelength input 1 on the outgoing route from node 1 to node N, and transmitting at wavelength λ2 on the return route from node N to node 1.

In order to configure a double loop network, the above-mentioned configuration may be made into two systems. For example, if a failure occurs at point a, the required function can be satisfied by loopback shown in FIG.

Effects of the Invention According to the present invention, a loop network can be configured with at least one optical fiber, and the system can be simplified and lowered in price.

[Brief explanation of the drawing]

1 and 2 are system block diagrams of an optical fiber communication LAN according to an embodiment of the present invention, and FIGS. 3 and 4 are system block diagrams of a conventional optical fiber communication LAN. 1-N...Node, Elo...Optical transmitter, O/E・
...Optical receiver, WDM...Optical multiplexer/demultiplexer. Name of agent: Patent attorney Toshio Nakao Figure 3

Claims (1)

[Claims] N nodes (N≧3) including the start point and end point provided on a path connecting the start point and the end point (for example, on a straight line) are connected in cascade with one optical fiber, and the start point is used as the starting point. The outgoing route to the end point is transmitted at wavelength λ1, and the return route from the end point node to the starting point is transmitted at wavelength λ2, which is different from λ1.
An optical fiber communication LAN characterized by transmission.