JPH06120965A - Transmission line control system - Google Patents

Abstract

PURPOSE:To provide a transmission line control system capable of securing the transmission line of data exchange between SN(slave node) which lost a communication line with MN(master node) and completing loop control in a short time. CONSTITUTION:Terminal data are transmitted to both duplex transmission lines 47 and 37 by a node device for which the channel connection of a terminal equipment 5 is set and reception data are received by selecting one (36) of the duplex transmission lines 36 and 46. When a fault occurs on the transmission line, fault information is transmitted to the node device which detected the fault and the transmission line 36 selected for reception is autonomously changed to 46 by the node device for which the channel connection of the terminal equipment 5 is set when the fault information is detected at a channel interface 7. When the fault occurs on the transmission line, the node device autonomously switches a reception transmission line and secures the transmission line for bypassing a fault position between the node device of a communication destination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line control method for a loop type network used for a local area network (LAN), an exchange, etc. It is configured so that it can respond appropriately.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional loop type LAN is a far station node device to which a central node device MN (master node) having a LAN loop control function and user terminals 52 and 54 are connected. SNs 1 to 5 (slave nodes) are provided, and they are connected by a double loop of 0-system transmission lines 30 to 35 and 1-system transmission lines 40 to 45 for transmitting information in opposite directions. A maintenance terminal 6 is connected to the MN in addition to a normal terminal.

As shown in FIG. 6, each node device (common to MN and SN) has a 0-system transmission line interface 3 and a 1-system transmission line interface 4 for interfacing with each of the double loops, and transmission for transmitting signals. Transmission path switching means 63 for switching the path system to 0 system or 1 system, multiplexing / demultiplexing means 64 for multiplexing or demultiplexing signals, transmission path system switching means 63 and multiplexing / demultiplexing means 64 The node control means 8 for controlling the switching operation of the system 1 and the line interface 7 serving as an interface with the terminal device 5 are provided, and the 0-system transmission line interface 3 and the 1-system transmission line interface 4 are transmission circuits. , A receiver circuit having a failure detection function. Further, in the MN, the maintenance terminal 6 is connected to the node control means 8.

In the LAN of FIG. 5, a logical communication path 10 for control information is secured on the loop type transmission path between the node control means 8 of each SN and the node control means 8 of the MN, and information is exchanged. Between the terminal device 52 of SN2 and the terminal device 54 of SN4 for performing the above, the logical communication path 11 for multiplex signal transmission is secured on the loop type transmission path.

When the transmission line is in a normal state, the 0-system transmission lines 30 to 35 in the double loop are used as an operating system for transmitting information, and the other 1-system transmission lines 40 to 45 are in trouble. It is used as a standby system to prepare for.

As shown in FIG. 7, for example, the 0-system transmission line 31
If a failure occurs in the 1-system transmission path 41 and communication between SN1 and SN2 becomes impossible (a), in order to secure a ring-shaped transmission path that bypasses the failure point, one of A control of the transmission line called "loopback" is performed in which the system is used as a bypass for the other system.

In this case, the occurrence of a failure is detected by the receiving circuit of the 0-system transmission line interface 3 of SN2 and the receiving circuit of the 1-system transmission line interface 4 of SN1.
When the node control means 8 of SN2 and SN1 receive the notification of the failure occurrence detection from each receiving circuit, the failure information is transmitted to the node control means 8 of the MN via the logical communication path 10.
(b).

Upon receiving the fault information of both systems, the node control means 8 of the MN specifies the loopback execution node and instructs the node control means 8 of the specified SN1 and SN2 via the logical communication path 10. Send information (c).

Upon receiving the loopback instruction information, SN1 and SN2 start loopback, SN1 transmits the signal received by the 0-system transmission line interface 3 from the 1-system transmission line interface 4, and SN2 The signal received by the 1-system transmission path interface 4 is transmitted from the 0-system transmission path interface 3. By doing this, the terminal
A ring-shaped communication path is secured between 52 and 54 (d).

When the failure of the transmission lines 31 and 41 is recovered, S
Receiving circuit of S1 transmission line interface 4 of N1 and S
The receiving circuit of the 0-system transmission line interface 3 of N2 detects that the transmission line has returned to the normal state, and the node control means 8 of each SN notified of the detection result detects the logical communication line 10
The failure recovery information is transmitted to the node control means 8 of the MN via (e).

The node control means 8 of the MN, which has received the failure recovery information of both systems, passes the logical communication path 10 to the SN1, S
The loopback cancellation instruction information is sent to the node control means 8 of N2, and SN1 and SN2 which received this instruction complete the loopback and return to the initial state (f).

[0012]

However, according to the conventional transmission line control method for a double loop type network, as shown in FIG. 8, when multiple failures occur at a plurality of transmission line locations, communication with the MN occurs. SN2 and SN that lost the control logical communication path 10
3 and SN4 are excluded from the targets of loop control, and all communication on the transmission path is cut off. Therefore, it has a drawback that communication between the terminal devices 52 and 54 connected to these SNs becomes impossible.

Further, in the conventional method, since the loop control is performed via the MN, there is a problem that the time from the occurrence of a failure to the completion of the loop control is long, and all the communication paths are incapable of communication for a long time. I'm holding.

The present invention solves these problems of the conventional system, and the SN that lost the communication path with the MN.
It is an object of the present invention to provide a transmission line control method for a dual loop network, which can secure a transmission line for data exchange between each other and can complete loop control in a short time.

[0015]

Therefore, in the transmission path control system of the present invention, a node device which has established a line connection of a terminal device is caused to send terminal data to both of the dual transmission paths, and receive data is sent to two terminals. When one of the multiple transmission paths is selected and received, and when a failure occurs in the transmission path, the failure information is sent to the node device that has detected the failure, and this failure is sent to the node device that has set the line connection of the terminal device. When the information is detected, the transmission path selected for reception is autonomously changed.

Further, the terminal data is multiplexed and transmitted in a loop revolving frame that revolves around the double transmission path.

In addition, in this multiplexing, data is multiplexed only in the selected time slot Add /
Drop multiplex means is used.

Further, the terminal data is transmitted by using an SDH (Synchronous Digital Hierarchy) multiplexing structure.

Further, failure information is transmitted by using POH (path overhead) of SDH.

[0020]

[Operation] Therefore, if a failure occurs in the transmission line,
The node device autonomously switches the reception transmission path and secures a transmission path that bypasses the failure point with the node device of the communication destination.

The Add / Drop multiplexing means multiplexes and demultiplexes data at the time slot positions corresponding to the terminal lines of the loop circulation frame, and passes the data at other time slot positions as they are. Therefore, the node device to which the line connection of the terminal device is not set only relays the data.

When data is transmitted using the SDH multiplexing structure, all the user data is changed to 1 in response to the occurrence of a failure in the transmission path, and this signal is sent as failure information. .

Furthermore, when the SDH multiplexing structure is used for data transmission, POH can also be used as an area for transmitting fault information.

[0024]

[Embodiment] Regarding the transmission path control system of the embodiment of the present invention,
This will be described using the LAN shown in FIG. This LAN is M
N and SN are connected by the 0-system transmission lines 30 to 35 and the 1-system transmission lines 40 to 45 to form a loop network. Further, each of the SN and MN has a terminal device 50-
55 is connected, and the maintenance terminal 6 is further connected to the MN.

The data output from each of the terminal devices 50 to 55 is multiplexed at the time slot position determined for each terminal line of the loop revolving frame that revolves around the loop, and transmitted from node to node.

The configuration of each node device (common to MN and SN) is as follows:
As shown in FIG. 1, the 0-system transmission line interface 3 that receives the signal of the 0-system transmission line 36 and transmits the signal to the 0-system transmission line 37
And a 1-system transmission line interface 4 that receives a signal of the 1-system transmission line 46 and transmits a signal to the 1-system transmission line 47, and multiplex / demultiplex data with respect to the selected time slot of the loop circulation frame Add / Drop multiplexing means 61 that allows unselected time slots to pass through as is, and the time slot position of the loop revolving frame corresponding to each terminal line is stored, and the data of each terminal line is multiplexed into the loop revolving frame.
A time-space exchange (cross-connect) means 62 for requesting a time slot to be selected to the Add / Drop multiplexing means 61 for separation, and a line interface 7 for interfacing with the terminal device 5, And a node control means 5 for monitoring and controlling the operation in the node device.

The 0-system transmission line interface 3 and the 1-system transmission line interface 4 are provided in the transmitting circuits 39 and 49.
And the receiving circuits 38 and 48 that detect a failure according to the reception level.
The receiving circuits 38 and 48 have a function of setting all binary values of the terminal data to be output to the Add / Drop multiplexing means 61 to 1 when detecting a failure in the transmission path.

Further, the line interface 7 has a failure information detecting function for detecting this all-one data (referred to as "all-one data"). The exchange means 62 is notified of that fact.

This node device multiplexes the terminal data into the determined time slot position of the loop revolving frame, and through the transmitting circuit 39 of the 0-system transmission line interface 3 and the transmitting circuit 49 of the 1-system transmission line interface 4, It is output to both the 0-system transmission line 37 and the 1-system transmission line 47. Therefore, the 0-system transmission lines 30 to 35 and the 1-system transmission lines 40 to 45 respectively transmit the same data in opposite directions.

On the other hand, upon reception, the 0-system transmission lines 30 to 35
And one of the loop revolving frames revolving around the system 1 transmission lines 40 to 45 is selected, and the data at the time slot position determined for the terminal line is separated from the frame and sent to the terminal device 5. It

The selection of the loop revolving frame at the time of reception is performed by the Add / Drop multiplexing means 61 in response to the transmission / path selection request output from the time / space switching means 62 through the selection request means 91. Further, the multiplexing / demultiplexing of data at the determined time slot position is requested by the time / space exchange means 62 through the multiplexing request means 92, and in response to this, the Add / Drop multiplexing means 61 executes it.

The operation of transmitting and receiving this terminal data is shown in FIG. Loop loop frame 12 received from 0-system transmission line
Also, in the loop circulation frame 22 received from the transmission path of the 1st system, data to be transmitted to the terminal devices 56 and 57 is multiplexed at the same time slot position. These frames 1
Reference numerals 2 and 22 are reception circuits of the transmission line interface, and the mutual frame phases are aligned.

The Add / Drop multiplexing means 61 separates the corresponding time slot data from the selected frame,
Reconstruct new frame 27. The time slot data 14 selected from the 0-system transmission line and the time slot data 24 selected from the 1-system transmission line are separated by the time / space exchange means 62, and the respective terminal devices 56 and 57 are separated.
Data 15 and 25 are sent to

On the other hand, the data 16 and 26 output from the terminal devices 56 and 57 are Add / Received by the time / space exchange means 62.
The drop multiplexing means 61 multiplexes the loop loop frames 13 and 23 which circulate around the 0-system transmission line and the 1-system transmission line at predetermined time slot positions and sends them to both transmission lines.

In the node device to which the line connection with the terminal device 5 is set, in order to multiplex / separate the data into the predetermined time slot position of the loop revolving frame, the time slot position of the loop revolving frame and the terminal line. The time / space exchange means 62, which stores the relationship with, through the selection request means 92, selects the time slot to be multiplexed / demultiplexed.
Request to Add / Drop multiplexing means 61.

At the time of transmission, the Add / Drop multiplexing means 61 multiplexes the terminal data only in the time slot for which the loop revolving frame is requested, and passes the time slot not requested as it is (thus, As a node device, it will perform a relay operation). Further, upon reception, the data of the time slot requested by the time / space switching means 62 is obtained from the selected transmission path and output to the time / space switching means 62.

When a fault occurs at any part of the loop, the receiving circuits 38 and 48 of the transmission line interfaces 3 and 4 detect the fault in the node device at the position where the signal is received from the transmission line in which the fault has occurred. Add / Drop multiplexing means 61
Convert the data to be output to all 1 data.

If this node device has not established a line connection with the terminal device, all 1 data is relayed to the next node device, and this node device also establishes a line connection with the terminal device. If not, the data in the time slot is not changed and is relayed to the next node device as it is.

When all 1 data in the time slot relayed in this way is received by the node device that is exchanging data at the time slot position and exchanging data with the terminal device, Add / Drop multiplexing is performed. It is separated by the means 61 and sent to the line interface 7 via the time / space exchange means 62. When the line interface 7 detects this all 1 data, it notifies the time / space switching means 62 of the occurrence of a failure through the failure detection notifying means 90.

Time / space exchange means notified of failure occurrence
62 changes the selection of the reception transmission path which has been requested through the selection requesting means 91 up to that point, and based on this, Add / Drop
The multiplexing means 61 switches the reception transmission path.

Therefore, in the node device which has separated the data from the loop circulation frame which circulates around the 0-system transmission line in the initial state and sent it to the terminal device, when a failure occurs upstream of the 0-system transmission line, it is sent. The line interface 7 detects all 1 data coming and notifies the time / space exchange means 62 of the failure. As a result, the transmission path to be received is switched and changed so as to separate the data from the loop revolving frame that revolves around the 1-system transmission path.

FIG. 3 shows S in response to the occurrence of a failure in the transmission line.
It shows a process in which N autonomously switches the transmission path and secures the transmission path that bypasses the failure occurrence point.

Now, SN2 is about the terminal device 52,
It is assumed that the SN 5 sets up a line connection for the terminal device 55 and data is exchanged between the terminal device 52 and the terminal device 55 through the loop transmission line.

The terminal data output from the terminal device 52 is the SN
The terminal data sent from the 2nd to 0th system transmission path 32 and the 1st system transmission path 41 and output from the terminal device 55 is transmitted from SN5 to 0th.
It is sent to the system transmission line 35 and the 1st system transmission line 44. On the other hand, when receiving, SN2 is the 0-system transmission line in the initial state.
It is assumed that 31 is selected and the SN 5 selects the 1-system transmission line 45 to receive data. Therefore, the terminal device
The data output from 52 is SN2, system 1 transmission path 41, S
The data output from the terminal device 55 reaches the terminal device 55 via the N1 and 1 system transmission lines 40, MN, the 1 system transmission line 45, and SN5, while the data output from the terminal device 55 is the SN5 and 0 system transmission lines 35, MN, and 0 system. Transmission line
It has reached the terminal device 52 via 30, SN1, 0-system transmission line 31, SN2 (a).

Simultaneously with the transmission line between SN1 and SN2 (0-system transmission line 31, 1-system transmission line 41) and the transmission line between SN5 and MN (0-system transmission line 35, 1-system transmission line 45). When a failure occurs (b), in SN2, the receiving circuit 38 of the 0-system transmission path interface 3 detects the failure occurring in the 0-system transmission path 31 and changes the data of the time slot into all 1 data. Ad
Output to the d / Drop multiplexing means 61. Line interface 7
Detects all 1 data and notifies the time / space switching means 62 of the occurrence of a failure, and the Add / Drop multiplexing means 61 switches the reception transmission line according to a request from the time / space switching means 62, As a result, the reception transmission path is changed to the 1-system transmission path 42.

In SN5, the receiving circuit 48 of the 1-system transmission line interface 4 detects a failure that has occurred in the 1-system transmission line 45, and the receiving transmission line is changed to the 0-system transmission line 34 through the same procedure. .

As a result, the data output from the terminal device 52 is SN2, 0 system transmission line 32, SN3, 0 system transmission line 33,
The data that reaches the terminal device 55 via the SN4, 0-system transmission line 34, and SN5, while the data output from the terminal device 55 is SN
5, 1-system transmission line 44, SN4, 1-system transmission line 43, SN3, 1
The terminal device 52 arrives at the terminal device 52 via the system transmission path 42 and SN2 (c).

As described above, in the transmission path control system of the embodiment, the SN separated from the MN due to the occurrence of multiple failures.
Even if the above occurs, it is possible to perform data transmission between the terminal devices connected to those SNs.

Further, in this transmission path control method, the time required from the occurrence of a failure to the switching of the transmission path is the failure detection time for detecting the failure at the transmission path interface on the receiving side and the loop circulation frame from the failure point. The transmission delay time transmitted to the node device to which the terminal device is connected, the detection protection time expected to detect all one data at the line interface 7, and the transmission path to be received by the time / space exchange means 62 are selected. The total length is the control time.

When the loop revolving frame of 125 μs is used, the fault detection time is 1 ms or less, the transmission delay time and the detection protection time of all 1 data are about several ms, and the control time is 1 ms or less. Even if the whole is combined, the transmission line control for compensating the transmission line failure can be performed in a very short time of the order of m seconds.

In this transmission path control system, bidirectional communication can be ensured even if failures occur at three or more locations as long as the bidirectional transmission paths connecting the SNs are alive. Further, even when only one of the transmission lines between the SNs is alive, one-way communication can be performed using the transmission line.

When the transmission path is configured to transmit data by the SDH (Synchronous Digital Hierarchy) multiplexing structure, when a failure occurs in the transmission path,
The values of the transmitted data are all changed to 1. this is,
According to the SDIT regulations of CCITT, it is decided that the user data is changed to 1 in response to the occurrence of a failure in the transmission path in the upstream, and an SDH-compliant device such as an LSI must meet this regulation. Because it is made.

This change of data is not different from the operation required by the receiving circuit of the node device of the embodiment. Therefore, in the transmission path control method of the present invention, the data is SD
Transmission by the H multiplexing structure is very beneficial.

According to CCITT rules, SDH
It has been decided to provide a POH (path overhead) area used for maintenance and monitoring of transmission lines.
It is also possible to use H for transmitting fault information.

The writing of data to the POH is performed by the receiving circuit of the transmission line interface which has detected the failure of the transmission line. The receiving circuit writes predetermined 8-bit data in the POH, and this failure information is detected by the line interface 7 in the same manner as all 1 data. The operation of the node device after the detection is the same as the case where all one data is used as the failure information.

[0056]

As is apparent from the above description of the embodiments, in the transmission path control method of the present invention, since each node device can autonomously change the transmission path, it is possible to avoid a MN due to multiple failures. Even if the communication path is interrupted, it is possible to secure the communication path between the SNs.

Further, the time required from the occurrence of a failure in the transmission path to the securing of the transmission path while avoiding the failure location is extremely short as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a node device that implements a transmission path control system of the present invention,

FIG. 2 is a configuration diagram of a network to which the transmission path control system of the present invention is applied,

FIG. 3 is a diagram showing a process of selecting a transmission line according to the transmission line control method of the present invention;

FIG. 4 is a diagram showing a procedure of data transmission / reception in the transmission path control system of the present invention;

FIG. 5 is a configuration diagram of a network to which a conventional transmission path control method is applied,

FIG. 6 is a block diagram of a node device that implements a conventional transmission path control method;

FIG. 7 is a diagram showing a process of selecting a transmission line according to a conventional transmission line control method;

FIG. 8 is a diagram showing a problem that a conventional transmission path control method has.

[Explanation of symbols]

 MN Master node SN1 to 5 Slave node 10 Control information logical communication path 11 Data exchange logical communication path 12, 13, 22, 23 Loop loop frame 14, 15, 16, 24, 25, 26 Data 27 Reconstruction frame 3 0 system transmission line interface 30 to 37 0 system transmission line 38 0 system interface receiving circuit 39 0 system interface transmitting circuit 4 1 system transmission line interface 40 to 47 1 system transmission line 48 1 system transmission line interface receiving circuit 49 1 system transmission Line interface transmission circuit 5, 50 to 57 Terminal device 6 Maintenance terminal 61 Add / Drop multiplexing means 62 Time / space switching means 63 Transmission line switching means 64 Multiplexing / demultiplexing means 7 Line interface 8 Node control means 90 Fault notification means 91 Selection request means 92 Multiplex request means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Nishi Nishi No. 3-1, Tsunashima Higashi 4-chome, Kohoku Ward, Yokohama City, Kanagawa Prefecture Matsushita Communication Industry Co., Ltd. 3-3-1 Matsushita Communication Industrial Co., Ltd.

Claims (5)

[Claims] 1. In a transmission line control system of a network in which a plurality of node devices are connected by using dual transmission lines that transmit data in opposite directions to each other, terminal data is set to a node device to which a line connection of a terminal device is set. Is sent to both of the dual transmission paths, and one of the dual transmission paths is selected to receive the received data. When a failure occurs in the transmission path, the failure information is sent to the node device that has detected the failure. Is transmitted to the node device, which has set the line connection of the terminal device, and autonomously changes the transmission line selected for reception when the failure information is detected. 2. The transmission path control method according to claim 1, wherein the terminal data is multiplexed and transmitted in a loop revolving frame that revolves around the dual transmission path. 3. The transmission path control system according to claim 2, wherein upon multiplexing, Add / Drop multiplexing means for multiplexing data only in a selected time slot is used. 4. The transmission path control method according to claim 1, wherein the terminal data is transmitted using an SDH (Synchronous Digital Hierarchy) multiplexing structure. 5. The transmission path control method according to claim 4, wherein the failure information is transmitted by using POH (path overhead) of the SDH.