JPS6298839A - Optical loop constructing method - Google Patents

Abstract

PURPOSE:To shorten the time necessary for completing reconstruction by coping with a trouble in such a way that if duplicated transmission lines are all disconnected, the prescribed system transmits and receives a signal as long as optical signals from both systems arrive, and if only the one signal is disconnected, the system where light arrives is received and each communication node executes the loopback transmission to the opposite system. CONSTITUTION:Each node where the duplicated transmission lines connect can take a forward state and a loopback state in it. If both two optical transmission lines connecting nodes 403 and 404 are cut, a node 401 being a supervisory control station detects the trouble, and issues the instruction of reconstruction to all nodes. Thus each node takes a forward state or a loopback state in accordance with received optical signals from systems '0' and '1'. Namely, the nodes 411, 412 and 415 take forward states because light comes to all the systems. The nodes 413 and 414 take a loopback state because light does not come from the system '0' and '1', respectively. Thus the reconstruction is completed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical loop transmission system.9 In particular, when a fault occurs in which both systems are cut off in a duplex transmission line, the present invention can be used to quickly and The present invention relates to an optical loop configuration method suitable for simply reconfiguring a transmission path and recovering from a failure.

[Background of the invention]

The conventional device is as described in the document ``Optical Fiber Information Network: Detour, et al. Published by Shokodo (1982)''.
As a reconfiguration method using loopback, which is a relief method when two duplexed transmission lines are disconnected at the same time, the method described below has been used. As shown in FIG. 1(a), if both the optical fibers connecting the node 103 and the node 104 are cut, the node 101, which is the supervisory control station,
- [Detects a failure and issues a loopback instruction to all swords. As a result, all swords enter a loopback state as shown in FIG. 1(b). Next, while unpacking the loop sequentially in one direction from the node 111, it is checked whether a failure occurs. That is, the node 112 is released from loopback, checked to see if a failure has occurred, and if no failure has occurred, the loopback of the next node 113 is released. Figure 1 (C
), the transmission path between nodes 123 and 124 is disconnected and a failure occurs, so node 123
returns to loopback state. Next, loopback is sequentially canceled in the opposite direction, and the presence or absence of a failure is checked. The loopback is canceled one after another until a failure occurs, and when the failure occurs, the node is returned to the loopback state and the process is terminated. At this time, the first
As shown in Figure (d), the reconfiguration is completed and the operation is resumed.

However, as shown above, the traditional design! The problem with this method is that it takes a long time to complete the reconfiguration because it puts all nodes into a loopback state and then releases the loopback state one by one while checking for failures.

[Purpose of the invention]

An object of the present invention is to quickly and simply reconfigure the transmission path in order to maintain and continue system operation when both duplex transmission paths are disconnected in an optical loop transmission system. The object of the present invention is to provide an optical loop configuration method that enables early recovery from a failure by performing reconfiguration.

[Summary of the invention]

In an optical loop transmission system with duplexed transmission lines, when both duplicated transmission lines are disconnected and a reconfiguration instruction is received from the monitoring node, each communication node switches to optical transmission line 0.
If a normal optical signal has arrived in both systems, system 0 and system 1, the forward state is set to send the signal to the downstream of the same system as the receiving system, and the optical transmission lines system 0 and system 1 are If a normal optical signal arrives from only one system, or if a normal optical signal does not arrive from either system, both optical transmission lines 0 and 1 should receive the signal. A loopback state is established in which a signal is sent to the downstream side of the system opposite to the system. A node in a loopback state transmits from upstream to downstream if a normal optical signal arrives on each route being looped back, but if a normal optical signal does not arrive, If not, stop the optical signal downstream.

By performing the above operations, after the transient state of the optical path selection logic due to the difference in arrival times of optical signals has passed in each communication node, the fault location is isolated and the reconfiguration of the system is completed.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

Each node connected to the duplexed transmission path is configured to have two states with different transmission paths within the node, that is, a forward state and a loopback state. FIG. 2 shows the state of the transmission path when the node is in the forward state. The transmission lines are duplicated, and each line rotates in opposite directions to form a loop. The clockwise route formed by the optical transmission line 201 and the optical transmission line 202 is referred to as a 0-system optical transmission line, and the counterclockwise route formed by the optical transmission line 204 and the optical transmission line 203 is referred to as an l-system optical transmission line. In the forward state, by setting the switches 216 and 217 as shown in FIG.
2 is converted into an electrical signal, received and processed by the receiving circuit RA (2Q8), and then from the transmitting circuit TA (209), passes through the switch 217, is converted to an optical signal by the optical transmitter 214, and is sent to the same O system. The signal is transmitted to an optical transmission line 202 which is an optical transmission line. Similarly, in the 1-system optical transmission path, the switch 216 performs reception and transmission to the same system.

FIG. 3 shows the state of the transmission path when in the loopback state. In the loopback state, by setting the switches 316 and 317 as shown in FIG. 3, the optical signal arriving from the O-system optical transmission line 301 is converted into an electrical signal by the optical receiver 312, and is then received. Circuit RA (30
After being received and processed in 8), the transmitting circuit TA (309)
The signal passes through a switch 316, is converted into an optical signal by an optical transmitter 313, and is transmitted to an optical transmission line 303, which is the opposite 1-system transmission line. Similarly, the optical signal entering from the 1-system optical transmission line 304 is sent back to the O-system optical transmission line by the switch 317. In the loopback state, the 0-system optical transmission line 3
The optical signal from 01 is sent to the optical receiver 312 and the receiving circuit R.
At A (308), it is monitored, and if a normal optical signal has not arrived, the optical transmitter 313 is configured not to emit light to the 1-system optical transmission line 303 that should be returned. .

Similarly, the optical signal from the 1st optical transmission line 304 is monitored at the optical receiver 315 and the receiving circuit RB (310), and if a normal optical signal has not arrived, the optical signal is sent to the optical transmitter 314. On the other hand, no light is emitted to the 0-system optical transmission line 302 that should be turned back.

Referring to FIG. 4, a reconfiguration according to the present invention will be described in the case where failures occur simultaneously at the same location in both the 0 and 1 systems. As shown in FIG. 4(a), when both optical transmission lines connecting node 403 and node 404 are broken, node 401, which is a supervisory control station, detects the failure and sends a message to all nodes. Issue reconfiguration instructions. Each node thereby assumes a forward state or a loopback state depending on the received optical signals of the O system and the I system, respectively. That is, as shown in FIG. 4(b), the nodes 411. Nodes 412 and 415 are in the forward state because light is coming from both systems. Node 413 is in a loopback state because there is no light coming from the O system, and node 414 is in a loop bank state because no light is coming from the 1 system. Take. This completes the reconfiguration.

In FIG. 5, a reconfiguration according to the present invention will be described in a case where a failure occurs in different locations of the 0 system and the 1 system. As shown in FIG. 5(a), when the 0-system optical transmission line between nodes 503 and 504 and the l-system optical transmission line between nodes 504 and 505 are disconnected, the monitoring and control station The node 501 detects the damage and issues a reconfiguration instruction to all nodes.This allows each node to enter the forward state or loopback state depending on the received optical signals of the O system and 1 system. , i.e., Fig. 5(b)
As shown in node 511. Node 512. node 5
Since light is coming from both systems, 14 assumes a forward state. Node 513 enters a loopback state because no light comes from the 0 system, and node 515 enters a loopback state because no light comes from the 1 system. 0 at node 513
On the path that returns from the system to the 1st thread, no light is coming from the 0th system, so the light to the 1st thread is stopped. Similarly, at the node 515, on the route back from the 1 system to the O system, no light is coming from the 1 system, so it stops passing to the 0 system. As a result, as shown in FIG. 5(C), the node 524 enters a loopback state because no light comes from both systems, and the reconfiguration is completed. In addition, in such a failure, by reconfiguration, the connected 524 sandwiched between the two failures is separated from the loop.

In Figure 6, the positional relationship is different from that in Figure 5, and 0
The reconfiguration according to the present invention will be described in the case where a failure occurs in the system and system 1 at different locations. As shown in FIG. 6(a), when the 1-system optical transmission line between nodes 603 and 604 and the 0-system optical transmission line between nodes 604 and 605 are broken, the node that is the supervisory control station At step 601, a failure is detected and a reconfiguration instruction is issued to all swords. As a result, υ each node assumes the forward state as well as the forward state and loopback state due to the received optical signals of the respective O and 1 systems. node 614
Since there is no light coming from the 0 and 1 systems, the loopback state is established, and since no light is coming from both systems, the light to both systems that should be looped back is stopped.

As a result, as shown in FIG. 6(C), node 623 no longer receives light from the O system, so it enters a loopback state, and node 625 no longer receives light from the 1 system, so it loops back. The reconfiguration is completed by changing to the puncture state.

Similarly, in other cases, if both transmission lines are broken, each node monitors the light in both systems according to a reconfiguration instruction from the supervisory control station, and returns to a forward state or loopback state. By controlling the folded and transmitted light according to the state and now the received light, the fault is isolated and the loop reconfiguration is complete after the optical routing logic transient has passed.

〔Effect of the invention〕

In the conventional method of sequentially sending a loopback cancellation instruction to each node, the reconfiguration time increases in proportion to the number of nodes. It is a simple method that does not require control using packets, etc., regardless of the number, and there is no need for packet generation time for instructions, and the reconfiguration is completed in the time required for node state transitions due to turning on and off of lights. can be reconfigured in a short time.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a rich configuration from a double failure in a transmission line according to a conventional method. Fig. 2 is a circuit diagram showing the forward state of the node in the present invention, Fig. 3 is a circuit diagram showing the loopback state of the node in the present invention, and Fig. 4 is a circuit diagram showing the node in the forward state according to the present invention. An explanatory diagram of reconfiguration from a state where both are cut. FIGS. 5 and 6 are explanatory diagrams of reconfiguration from a state in which both systems are cut in different positional relationships according to an embodiment of the present invention. 101.111, 121.131... Supervisory control station and communication node, 102-105, 112-115, 122-
125.132-135...communication node, 106,1
16,126,136...0 system optical transmission line, 107,1
17,127,137...1 system optical transmission line, 201.2
02...0 system optical transmission line, 203.204...1 system optical transmission line, 205...route switching circuit, 208...receiving circuit RA, 209...transmitting circuit TA, 210...
Receiving circuit RB, 211... Transmitting circuit TB, 212°2
15... Optical receiver, 213, 214... Optical transmitter,
216゜Second Entrance 3 Figure 5' Figure 1 Section

Claims (1)

[Claims] In an optical loop transmission system that has a duplex transmission line, a function to detect whether a normal optical signal has arrived, and an optical transmission line control function, when both duplex transmission lines are disconnected. When optical signals from both systems are arriving, the optical signals are transmitted and received in the specified system, and when only one system is receiving the optical signals, the system receives the optical signals from the system where the light is arriving, and then returns and transmits to the opposite system. An optical loop configuration method characterized in that it is performed at each communication node.