JPH05268236A - Transmission line control method for double-loop communication device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to secure a communication path between the terminals 91 connected to the slave node SN that lost the communication path with the master node MN, and complete loop control in a short time. Provided is a transmission line control method of a dual loop type communication device which can be used. In a transmission line control method of a double loop type communication device, when a fault occurs in the transmission line 10 or the node device SN3, the fault occurrence and the node device SN4 which has detected the fault
The fault information notifying that the node device SN4 that has detected this
To transmit the fault information to all the node devices in sequence, and have each node device autonomously perform loop control according to the location of the fault. Each node device recognizes a fault occurrence section from the fault information, and autonomously performs loop control such as system switching or loop back according to the fault occurrence situation.

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 system for a loop type communication device used in a local area network (LAN), an exchange, etc., and is particularly suitable for occurrence of a fault on the transmission line. It is configured so that it can respond accurately.

[0002]

2. Description of the Related Art In a conventional loop type LAN, as shown in FIG. 39, a central node device (hereinafter, referred to as MN; master node) having a LAN loop control function and a remote node connecting a user terminal 91 are connected. Station node device (hereinafter referred to as SN; slave node), and the 0-system transmission line 10 between them.
And the 1-system transmission line 11 are connected by a double loop.
A maintenance terminal 90 is connected to the MN in addition to a normal terminal.

Each node device (common to MN and SN) has a diagram
As shown in 40, a 0-system transmission line interface 50 and a 1-system transmission line interface 51 that interface with each of the double loops, a transmission line system switching circuit 71 that switches the transmission line system to 0 system or 1 system, and a signal. An interface between a terminal, and a multiplexing / demultiplexing circuit 72 for performing multiplexing or demultiplexing, a node control circuit 6 for controlling the switching operation of the transmission path switching circuit 71 and the multiplexing / demultiplexing circuit 72, and a terminal. The 0-system transmission line interface 50 and the 1-system transmission line interface 51 are provided with transmission circuits 52 and 54 and reception circuits 53 and 55 having a failure detection function. Further, in the MN, the maintenance terminal 90 is connected to the node control circuit 6.

In the LAN shown in FIG. 39, between the control circuit 6 of each SN and the control circuit 6 of the MN, a logical communication path 3 for control information is secured on a loop type transmission path, and communication is performed. Between the terminal 91 of SN2 and the terminal 91 of SN4,
A logical communication path 2 for transmitting multiple signals is secured on the loop type transmission path. In steady-state communication, the 0-system transmission line 10 in the double loop is used as the operating system, and the other 1-system transmission line 11 is used.
Is used as a standby system to prepare for failure.

Here, as shown in FIG. 41, the 0-system transmission line 10
When a communication failure occurs in that section and communication in that section becomes impossible, loop control called "system switching" that changes the 1-system transmission line 11 to the active system and the 0-system transmission line 10 to the standby system, The steps are performed in the following order, whereby a ring-shaped transmission path is secured.

The occurrence of a failure is detected by the receiving circuit 53 of the 0-system transmission line interface 50 of SN2, transmitted from this transmission line interface 50 to the node control circuit 6, and transmitted from the node control circuit 6 via the logical communication line 3. Then, the fault information is transmitted to the node control circuit 6 of the MN (FIG. 42).

Upon receiving the failure information, the node control circuit 6 of the MN sends the transmission path system switching instruction information to the node control circuits 6 of all the SNs via the logical communication path 3 (FIG. 43).

Upon receiving the transmission path switching instruction, the node control circuit 6 of each SN issues a switching operation instruction to the 0-system / 1-system switching circuit 71 to perform loop switching using the 1-system transmission path 11 as the active system. As a result, a ring communication path between the terminals 91 is secured (FIG. 44).

When the failure is recovered, failure recovery information is notified to the node control circuit 6 from the 0-system transmission path interface 50 of SN2 which has detected the normality of the transmission path, and passes through the logical communication path 3 to the node control circuit of the MN. Failure recovery information is transmitted to 6 (FIG. 45).

Upon receiving the failure recovery information, the node control circuit 6 of the MN sends the transmission path system switchback instruction information to the node control circuits 6 of all the SNs via the logical communication path 3. Switching the active system from the 1-system transmission line 11 to the 0-system transmission line 10 is called "system switchback". Each SN that has received the transmission path system switchback instruction information performs loop system switchback and returns to the initial state (FIG. 46).

Further, as shown in FIG. 47, when a failure occurs in both the 0-system transmission path 10 and the 1-system transmission path 11 and communication in that section becomes impossible, the failure location is bypassed. Therefore, one system is used for bypassing the other system, and a transmission line control called "loopback" that forms a ring-shaped transmission line is performed.

In this case, the occurrence of a failure is detected by the 0-system transmission path interface 50 of SN2 and the 1-system transmission path interface 51 of SN1, and failure information is transmitted from the node control circuit 6 of SN2 and SN1 to the logical communication path 3. It is transmitted to the node control circuit 6 of the MN via the route (FIG. 48).

The node control circuit 6 of the MN, which has received the fault information of both systems, specifies the loopback execution node and issues a loopback instruction to the node control circuits 6 of the specified SNs 1 and 2 via the logical communication path 3. Send information (Fig. 49).

Upon receiving the loopback instruction information, SN1 and SN2 start loopback, SN1 transmits the signal received by the 0-system transmission line interface 50 from the 1-system transmission line interface 51, and SN2 The signal received by the 1-system transmission line interface 51 is transmitted from the 0-system transmission line interface 50. By doing this, the terminal
A ring-shaped communication path is secured between 91 (Fig. 50).

When the failure is recovered, the 1-system transmission line interface 51 of SN1 and the 0-system transmission line interface 50 of SN2 respectively detect the normality of the transmission line, and the node control circuit 6 of each SN sends the logical communication line 3 The fault recovery information is transmitted to the node control circuit 6 of the MN via the
1).

The node control circuit 6 of the MN which has received the fault recovery information of both systems sends the loopback cancellation instruction information to the node control circuits 6 of all the SNs via the logical communication path 3 and receives this instruction. Each SN ends loopback and returns to the initial state (FIG. 52).

Further, as shown in FIG.
Fails and communication with a terminal connected to the SN and communication via the node are disabled, loopback is performed in the node devices on both sides of the node.

For example, if a failure occurs in SN3, the transmission line output to the adjacent SN2 and SN4 becomes abnormal. SN
When the transmission path interface circuits 50 and 51 of 2 and 4 detect the abnormality, they notify the failure occurrence information to the node control circuit 6 of each SN, and from this node control circuit 6 via the logical communication path 3, Fault information is transmitted to the node control circuit 6 of the MN (FIG. 54).

The node control circuit 6 of the MN, which has received the fault information of both systems, sends loopback instruction information to the node control circuits 6 of SN2 and SN4 (FIG. 55), and SN2 and S
N4 initiates loopback. As a result, the ring communication path between the terminals 91 is secured (FIG. 56).

When the failure is recovered, the transmission line interfaces 50 and 51 of SN2 and SN4 detect that the transmission line is normal,
Fault recovery information is transmitted from the SNs 2 and 4 to the node control circuit 6 of the MN (FIG. 57). The node control circuits 6 of the MNs send the loopback cancellation instruction information to the node control circuits 6 of all the SNs and return to the initial state (FIG. 58).

[0021]

However, in the conventional transmission line control method of the double loop type communication device, as shown in FIG. 59, for the control with the MN when multiple failures occur at a plurality of points. SN2, SN3 and SN that lost the logical communication path 3
No. 4 is excluded from the target of loop control, and all communication on the transmission path is cut off. Therefore, it has a drawback that communication between terminals connected to those 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 communicating 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 path control method for a dual loop communication device that can secure a communication path between terminals connected to each other and can complete loop control in a short time.

[0024]

Therefore, in the transmission path control method of the double loop type communication apparatus of the present invention, when a failure occurs in the transmission path or the node apparatus, the failure occurrence and the node apparatus detecting the failure are provided. Is transmitted from the detected node device, this fault information is sequentially transmitted to all the node devices, and each node device autonomously performs loop control according to the location of the fault.

Further, the fault information is continuously sent to the node device which has detected the fault until the fault is recovered.

SDH is also used for transmitting fault information.
(Synchronous Digital Hierarchy) SOH (section overhead) is used.

Further, in each node device, a time interval longer than the time required for the fault information to make a loop through the loop is detected from the detection of the fault or the reception of the fault information to the start of the loop control.

[0028]

Therefore, each node device receives the fault information and recognizes the faulty section by knowing the node device that detected the fault. Then, each node device autonomously performs loop control such as system switching or loop back according to the fault occurrence section. Therefore, even if the communication path between the SN and the MN is lost due to the failure, the S
It is possible to send and receive failure information between N and set a communication path corresponding to the failure.

Further, this loop control does not require the intervention of the MN one by one, so that the communication path can be secured in a short time.

[0030]

[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 in a loop by a 0-system transmission line 10 and a 1-system transmission line 11. A terminal device 91 is connected to each of the SN and MN, and a maintenance terminal 90 is further connected to the MN.

The configuration of each node device (common to MN and SN) is, as shown in FIG. 2, a 0-system transmission line interface 50 and a 1-system transmission line interface 51, and a transmission line for switching the transmission line system to 0 system or 1 system. A system switching circuit 71, a multiplexing / demultiplexing circuit 72 for multiplexing or demultiplexing signals,
It comprises a node control circuit 6 for controlling the switching operation of the transmission path switching circuit 71 and the multiplexing / demultiplexing circuit 72, and a line interface 8 serving as an interface with the terminal 91.

The 0-system transmission line interfaces 50 and 1
The system transmission line interface 51 is composed of transmission circuits 52 and 54 and reception circuits 53 and 55 having a failure detection function, and there is no communication between the node control circuit 6 and the 0 system transmission line interface 50.
In the system transmission path control bus 30, the node control circuit 6 and the system 1 transmission path interface 51 are connected by the system 1 transmission path control bus 31, respectively.

In this LAN, all the data are formed into SDH (Synchronous Digital Hierarchy) frames shown in FIG. 3A and transmitted on the transmission path. This frame (first frame) is composed of an overhead section (SOH) for transmitting control information between nodes, and a payload section for transmitting information that circulates around the loop in a second frame for 125 μsec. It is transmitted at a cycle of (8 kHz).

The SOH is terminated between the adjacent node devices,
The information in the SOH is updated / regenerated in each node device.

As shown in FIG. 3B, in the payload portion, the header portion, the error check information FCS by the cyclic code in the frame, and the 8-bit (Bch) time slot are collected to form the second portion. Frame is constructed. The first frame and the second frame are frequency-synchronized at 8 kHz.

The phase relationship between the first frame and the second frame is designated by the pointer inside the SOH, as shown in FIG. 3 (c). Therefore, one time slot enables communication at 64 kbit / sec, that is, communication equivalent to one telephone line.

Further, the first frames on the transmission lines in the adjacent sections are frequency-synchronized at 8 kHz.

In the SOH portion of the first frame, in addition to the pointer indicating the phase information, A1 /
A2, data communication channels D1 to D12, STM identification C
1, order wire E1 / E2, user channel F1, bit error monitoring B1 / B2, automatic switching signal channel K
1 / K2 and spare Z1 / Z2. Of these, the data communication channels D4 / D5 are used for transmitting the 0-system transmission path failure information and the 1-system transmission path failure information between adjacent nodes.

This fault information is displayed in the 1-byte format shown in FIG. The most significant bit indicates the occurrence of a failure, which is 1 when a failure is being detected and 0 when the failure is normal. The lower 7 bits represent the node number of the node device that has detected the failure, and can store the node numbers 0 to 127. When there is no abnormality in the transmission path, the failure information byte transmits 00h. When a failure occurs,
The node device which detects it stores 1 in the most significant bit and its own node number in the lower 7 bits, and continues to transmit this fault information to the transmission path until the fault is recovered.

FIG. 5 shows an algorithm defining the operation (transmission path control) to be taken by each node device in response to the failure information. In this figure, the failure information is classified into the following three items, and the operation of the node device is defined by the combination of the failure information of each item. (1) Information on whether or not a failure has been detected by the transmission path reception circuits 53 and 55 of the own node, and information on whether or not a failure has occurred on the reception side transmission path of the own node.
In FIG. 5, the “reception section transmission line” is displayed as “abnormal”. (2) Information on whether or not a reception failure is detected by the next node device, and information on whether or not the adjacent node has detected a failure in the transmission output of the transmission path of the own node.
It indicates that a failure has occurred in the transmission line on the transmitting side of the own node. This state is displayed as "abnormal" in "transmission section transmission line" in FIG. (3) Information indicating the presence / absence of a failure in the transmission path at other locations, and information indicating whether a failure has occurred in the transmission path other than the adjacent section.
Is displayed as "abnormal" in "other section transmission line".

First, if all transmission lines are normal and if a failure occurs only in the 1-system transmission line in any section, the 0-system transmission line 10 is used for operation. Therefore, the node device multiplexes / demultiplexes data on the 0-system transmission line 10.

When a failure has occurred only in the section of the 0-system transmission line 10, the node device switches the system to the 1-system transmission line 11 and multiplexes data to the 1-system transmission line 11. Demultiplex.

When a fault occurs in any section of the 0-system transmission line 10 and at the same time a fault occurs in any section of the 1-system transmission line 11, the node device performs loop back operation. A loop-shaped transmission line is formed. Data multiplexing / demultiplexing is performed on the 0-system transmission line 10. At this time, the node device in which the failure occurs in the receiving section of the 0-system transmission line 10 or the transmitting section of the 1-system transmission line 11 is the 1-system transmission line.
A loopback is performed from the reception of 11 to the transmission of the 0-system transmission line 10, and the node device in which the failure occurs in the reception section of the 1-system transmission line 11 or the transmission section of the 0-system transmission line 10 is the 0-system transmission line.
A loop back is performed from the reception of 10 to the transmission of the system 1 transmission line 11.

When failures occur simultaneously in the transmission sections of the 0-system and 1-system transmission paths 10 and 11, or when failures occur in the reception sections of the 0-system and 1-system transmission paths 10 and 11 at the same time, the node device Are isolated and cannot communicate between nodes.

FIG. 6 shows the fault information (detected node number) to be transmitted through each transmission line when each node device detects a fault or receives fault information from another node device.
Is specified.

The node device which has received the failure information from the 0-system transmission line 10 is the same as in the case where the own node detects the failure.
Send the received information as it is to the 0-system transmission line 10 (relay)
Similarly, the node device that has received the failure information from the 1-system transmission line 11 is
The received information is directly transmitted (relayed) to the 1-system transmission line 11.

When the fault is detected in the own node, the own node number is always included in the fault information.

Now, assuming that the following situations occur in the LAN shown in FIG. 1, (1) A failure occurs at one point of the 0-system transmission line 10 in operation, (2) 0-system transmission line 10 and 1-system transmission line
Failure occurs at the same point in 11 at the same time, failure occurs at another point in the 1-system transmission line 11 under the conditions of (3) and (1), and 0 system occurs under the conditions of (4) and (2). A failure occurs in another part of the transmission line 10, (5) a failure occurs in one node device, (6) (1) failure recovers, and (7) (2) failure recovers.

The operation of the LAN according to the transmission path control system of the embodiment at this time will be individually described.

[Operation corresponding to (1)] (FIGS. 7 to 10) As shown in FIG. 7, SN1 and S are connected to the 0-system transmission line 10 in operation.
When a failure occurs with N2, the 0-system transmission path receiving circuit 53 of SN2 detects a transmission path failure due to an abnormal reception level or the like, and the node control circuit 6 via the 0-system transmission path control bus 30.
To notify. The node control circuit 6 instructs the 0-system and 1-system transmission path interfaces 50 and 51 via the 0-system and 1-system transmission path control buses 30 and 31 to transmit the transmission path failure information.
In addition, the node control circuit 6 receives the system switching circuit via the multiplexing control bus 4 after the time (protection time) expected to be transmitted to each node device has passed.
Instructs 71 to switch the system.

The 0-system and 1-system transmission line interfaces 50 and 51 that have received the fault information transmission instruction are connected to the adjacent node SN1.
Then, using the 0-system transmission line fault information area in the SOH to SN3, the transmission of fault information notifying the occurrence of the transmission line fault and the detected node number is started (FIG. 8). This continues until there is a cancellation instruction from the node control circuit 6.

SN1 which has received the 0-system transmission path failure information from the 1-system transmission path 11 operates as follows.

The fault information regarding the 0-system transmission line 10 received by SN1 is only from SN2, and no fault is detected by SN1 itself. The system transmission path failure information is relayed to the 1-system transmission path 11, and the node control circuit 6 is notified of the failure information.

The node control circuit 6 determines that the failure detection node is the SN2 of the adjacent downstream node, and recognizes that a failure has occurred in the transmission section of the 0-system transmission line 10 of the own node. Further, since the failure information regarding the 1-system transmission line 11 has not been received, the system of the operation transmission line is switched to the 1-system transmission line 11 after the protection time has elapsed, based on FIG.

Further, the 0-system transmission line fault information is transmitted to the 0-system transmission line 10
The SN3 received from operates as follows.

In SN3 as well, since no failure is detected in SN3 itself, the 0-system transmission line interface 50
According to FIG. 6, the 0-system transmission line failure information is transmitted to the 0-system transmission line 10
It relays to the upper part, and also notifies the node control circuit 6 of the failure information.

The node control circuit 6 recognizes that the fault has occurred in the 0-system transmission line 10 other than the adjacent section, and has not received the fault information regarding the 1-system transmission line 11, so that the operation based on FIG. After the protection time has elapsed, the transmission line system is switched to the 1-system transmission line 11 (FIG. 9).

Similarly, each node device switches the system of the operation transmission line and detects the fault at the farthest end node (S2) of SN2.
When the fault information is transmitted to N5), the system switching is completed (Fig. 10).

The required time from the detection of a failure to the completion of the system switching is the transmission delay time (125 μsec × the number of nodes ×) of the loop halving until the failure information reaches the farthest end node.
This is the time obtained by adding the protection time and the time required for one node to switch the transmission path after receiving the failure information.

[Operation Corresponding to (2)] (FIGS. 11 to 16) As shown in FIG. 11, a failure occurs between SN1 and SN2 in both the 0-system transmission line 10 and the 1-system transmission line 11. When it occurs, SN
The 1-system 1 transmission line receiving circuit 55 and the SN 2 0-system transmission line receiving circuit 53 detect a transmission line failure due to an abnormal reception level or the like, and notify the respective node control circuits 6 to that effect. The node control circuit 6 of SN1 instructs the 0-system and 1-system transmission line interfaces 50 and 51 to send fault information of the 1-system transmission line 11, and the node control circuit 6 of SN2 transmits 0-system and 1-system transmission. 0 system transmission line 10 to the line interface 50, 51
To send the fault information of. Further, after the lapse of the protection time, the node control circuit 6 of SN2 instructs the system switching circuit 71 to switch the system to the 1-system transmission line 11 based on the algorithm of FIG. However, SN1 does not switch the system according to FIG.

0 of SN1 which received the instruction to send fault information
The system and system 1 transmission line interfaces 50, 51 use the system 1 transmission line fault information area in the SOH to notify the adjacent nodes MN and SN2 of the occurrence of the system 1 transmission line fault and the detected node number. Start sending failure information to notify (however,
It is not transmitted to SN2 due to a failure).

Similarly, the 0-system and 1-system transmission line interfaces 50 and 51 of SN2 use the 0-system transmission line failure information area in the SOH for the adjacent nodes SN1 and SN3. The transmission of the fault information indicating the fault occurrence and the detected node number is started (however, because of the fault, SN1
Not transmitted to) (Fig. 12). The transmission of these pieces of fault information is continued until the node control circuit 6 gives a cancellation instruction.

The MN which has received the system 1 transmission line fault information from the SN1 through the system 1 transmission line 11
It relays to SN5 via the 1-system transmission line 11. The transmission path control is left as it is based on FIG.

In SN3, which has received the 0-system transmission path failure information from SN2 via the 0-system transmission path 10, the failure information is relayed to SN4 via the 0-system transmission path 10 and the algorithm of FIG. Based on the above, after the protection time has passed, the active transmission line is switched to the 1-system transmission line 11 (Fig. 1
3).

Similarly, each node device that has received the 1-system transmission path failure information relays the failure information, receives the 0-system transmission path failure information, and each node device switches the operating transmission path.

When the fault information reaches the farthest end nodes (SN4 and SN5) of SN1 and SN2 where the fault is detected, SN4 and SN5 recognize the occurrence of the fault in the other section transmission lines of both systems. In this case, the algorithm of FIG. 5 causes loop back at any place, so that in SN4 and SN5, multiplexing / demultiplexing is performed with the 0-system transmission path as the operating system (FIG. 14).

The SN that has already established the 1-system transmission line 11 as the active system
When the 1-system transmission path failure information arrives at 3, system switching back is performed at SN3 based on FIG. 5 so that the 0-system transmission path 10 becomes the active system (FIG. 15).

When the transmission path failure information makes one round in the loop, the node devices SN1 and SN2 at both ends of the failure section start loop back based on FIG. 5 (FIG. 16).

The required time from the detection of a failure to the completion of loop back is that one node receives the failure information during the transmission delay time (125 μsec × (total number of nodes-1)) of the failure information making one round in the loop. From the transmission path system switching to the protection time. Further, when the protection time is set to be equal to or longer than the failure information transmission delay time, the failure information of both systems is transmitted to each node device before the protection time elapses. After that, the control for switching back to the 0-system transmission line 10 again disappears.

[Operation Corresponding to (3)] (FIGS. 17 to 20) As shown in FIG. 17, the 0-system transmission line 10 between SN1 and SN2.
In response to the occurrence of the failure, the system 1 transmission path 11 between SN5 and SN4 newly fails after the switching to the system 1 transmission path 11 is completed.
54 detects a transmission line failure and notifies the node control circuit 6 of it.

The node control circuit 6 instructs the 0-system and 1-system transmission line interfaces 50 and 51 to send the 1-system transmission line fault information, and according to the algorithm of FIG. The loop back is instructed to the system switching circuit 71.

0-system and 1-system instructed to send fault information
The system transmission line interfaces 50 and 51 respectively use the 1-system transmission line failure information area in the SOH and use the adjacent node SN3.
Then, the transmission of fault information notifying the occurrence of the 1-system transmission line fault and the detected node number to SN5 is started. At this time, since the 0-system transmission path interface 50 is receiving the 0-system transmission path failure information, the transmission path failure information to be sent to SN5 is the both-system failure information. The transmission of the fault information is continued until a cancellation command is issued from the node control circuit 6.

Next, SN5, which has received the 1-system transmission path failure information from the 0-system transmission path 10, knows that the 1-system transmission path failure has been detected by SN4 and recognizes the occurrence of a failure in the transmission section of its own node. To do. Therefore, the SN 5 relays the failure information of both transmission paths to the MN via the transmission path 10 of system 0, and starts loop back of reception of system 1 → transmission of system 0 based on FIG.

On the other hand, the SN3 which has received the 1-system transmission path failure information from the 1-system transmission path 11 recognizes the failure of both systems and relays the 1-system transmission path failure information to the SN2 through the 1-system transmission path 11. At the same time, based on FIG. 5, the 0-system transmission line 10 is switched back to the active system as an operation during loop back (FIG. 19).

Similarly, each node device that has received the 1-system transmission path failure information recognizes the failure of both systems and, based on FIG. 5, switches back to the 0-system transmission path operation during loop back operation. Do.

When the 1-system transmission line fault information is transmitted to the node devices (SN1 and SN2) at both ends of the 0-system transmission line fault occurrence section, SN1 and SN2 start loop back based on FIG. Yes (Fig. 20).

Thus, in response to the situation (3),
The LAN operates as two rings with loop back.

The required time from the detection of a failure to the completion of loop back is such that the failure information has a minimum of one half loop and a maximum of one.
1 for the round-trip transmission delay time (125 μs × total number of nodes)
It is the time that is obtained by adding the protection time and the time required for the node to switch the transmission path after receiving the failure information.

[Operation Corresponding to (4)] (FIGS. 21 to 23) As shown in FIG. 21, a loop back operation is performed in response to the occurrence of a failure in both transmission lines between SN1 and SN2. 0 line transmission line 10 between SN5 and SN4
When a failure occurs in the first line, the 0-system transmission line receiving circuit 53 of SN5 detects the transmission line failure and notifies the node control circuit 6 through the 0-system transmission line control bus 30.

The node control circuit 6 includes a transmission path control bus 30,
31 through 0 system and 1 system transmission line interface 50,
51 is instructed to transmit the 0-system transmission path failure information, and the system switching circuit 71 is instructed to loop back from 1-system reception to 0-system transmission according to the algorithm of FIG.

0 system and 1 which are instructed to send fault information
The system transmission line interfaces 50 and 51 respectively use the system 0 transmission line failure information area in the SOH and use the adjacent node SN4.
Then, the transmission of fault information notifying the occurrence of the 0-system transmission line fault and the detected node number to the MN is started.

At this time, the 0-system transmission line interface 50
Is receiving the 0-system transmission path failure information (depending on the content of the failure, the failure information detected by SN2 disappears in the failure section), but for the MN, based on FIG. Only the detected failure information is transmitted as the 0-system transmission path failure information.

The 1-system transmission line interface 51 is
Since the system transmission path failure information is being received, based on FIG.
Both system failure information is sent to SN4. The transmission of these pieces of fault information is continued until there is a cancellation command from the node control circuit 6 (FIG. 22).

Next, SN4, which has received the both-system transmission path failure information from the 0-system transmission path 10, knows that the 0-system transmission path failure has been detected by SN5 and recognizes the occurrence of a failure in the transmission section of its own node. To do. Therefore, SN4 relays both-system transmission path failure information to SN3 via the 1-system transmission path 11, and
Based on FIG. 5, the loop back of 0 system reception → 1 system transmission is started (FIG. 23).

Thus, in response to the situation (4),
The LAN operates as two rings with loop back.

The time required from the detection of the second fault to the completion of the loop back is determined by the transmission delay time (125 μsec) of the fault information to the adjacent node device after the one node receives the fault information. The total time is the time required for system switching and the protection time.

[Operation Corresponding to (5)] (FIGS. 24 to 29) When a failure occurs in the node device SN3 as shown in FIG. 24, first, the 1-system transmission line reception of the SN2 adjacent to the failed node device is performed. The circuit 55 and the 0-system transmission line receiving circuit 53 of SN4 are
A failure is detected due to an abnormal reception level or the like, and the fact is notified to each node control circuit 6.

The node control circuit 6 of SN4 instructs the 0-system and 1-system transmission line interfaces 50 and 51 to send the 0-system transmission line fault information, and the node control circuit 6 of SN2 sets 0.
It instructs the system and 1-system transmission line interfaces 50 and 51 to send the 1-system transmission line fault information. Further, the node control circuit 6 of SN4 instructs the system switching circuit 71 to switch the system to the 1-system transmission line 11 after the protection time has elapsed (FIG. 25).

In SN5, which has received the 0-system transmission line failure information from SN4, the failure information is transmitted to the M-system via the 0-system transmission line 10
While relaying to N, based on the algorithm of FIG.
After the protection time elapses, the operating system transmission path is switched to the 1-system transmission path 11, and the SN1 that has received the 1-system transmission path failure information from the SN2 through the 1-system transmission path 11 transmits this failure information to the 1-system transmission path. Relay to MN via path 11. The transmission line control is left as it is based on FIG. 5 (FIG. 26).

As described above, until the fault information is transmitted from the fault location to the farthest node device (MN), each node device relays the fault information and receives the 0-system transmission line fault information. In the device, system switching is executed.

When the fault information is transmitted to the MN of the farthest end node device, the MN recognizes the fault in both systems. In this case, since the loop back is performed at any place by the algorithm of FIG.
Is used as the operating system to perform multiplexing / demultiplexing (Fig. 27).

The SN that has already established the 1-system transmission path 11 as the active system
When the 1-system transmission path failure information arrives at 5, the SN 5 performs system switching back to make the 0-system transmission path 10 the active system based on FIG. 5 (FIG. 28).

When the transmission path fault information makes one round in the loop, the node devices SN2 and SN4 on both sides of the faulty node device.
Starts loopback based on Figure 5 (Figure 2
9).

The time required from the detection of a failure to the completion of loop back is that one node receives the failure information during the transmission delay time (125 μsec × (total number of nodes−2)) for the failure information to make one round in the loop. From the transmission path system switching to the protection time. Further, when the protection time is set to be equal to or longer than the failure information transmission delay time, the failure information of both systems is transmitted to each node device before the protection time elapses, so the system 1 is temporarily switched to the transmission path 11. After that, the control for switching back to the 0-system transmission line 10 is not necessary anymore.

[Operation Corresponding to (6)] (FIGS. 30 to 33) As shown in FIG. 30, when the fault occurring in the 0-system transmission line 10 between the node devices SN1 and SN2 is recovered. , SN
The second 0-system transmission line receiving circuit 53 detects the recovery of the transmission line failure by the recovery of the reception level, the establishment of synchronization, etc., and notifies the node control circuit 6 to that effect.

The node control circuit 6 instructs the 0-system and 1-system transmission line interfaces 50 and 51 to stop the transmission of the transmission line failure information, and after the protection time has passed, the system switching circuit 71 is turned off. Give back instructions.

The 0-system and 1-system transmission line interfaces 50 and 51 which have received the instruction to stop the transmission of the fault information are connected to the adjacent node S.
For N1 and SN3, stop transmission line fault information being sent, and set 00h in the 0th line transmission line fault information area in SOH.
Send SDH frame containing (However, if fault information is received from another node, relay it)
(Figure 31).

In SN1 which has received the 0-system transmission path failure recovery information (00h: no failure) from the 1-system transmission path 11, this is
It relays to the MN through the 1-system transmission line 11.

Further, SN3, which has received the 0-system transmission path failure recovery information from the 0-system transmission path 10, relays this to the SN4 through the 0-system transmission path 10.

Similarly, failure recovery information is relayed one after another and transmitted to the farthest end node SN5 of SN2.

When the 0-system and 1-system transmission path interfaces 50 and 51 of SN5 receive the 0-system transmission path failure recovery information through the 0-system transmission path and the 1-system transmission path, respectively, they notify the node control circuit 6 of failure recovery. .. When the node control circuit 6 receives the failure recovery notification from the transmission path interfaces 50 and 51 of both systems, based on FIG.
The system is switched back to return the system of the operating system transmission line to the system 0 transmission line 10 (FIG. 32).

Similarly, in each node device, the 0-system transmission line 10
When the 0-system transmission path failure recovery information is received from each of the 1-system transmission path 11 and the 1-system transmission path 11, the system of the operational transmission path is switched back, and the failure recovery information up to the adjacent nodes (SN1 and SN3) of the SN2 that detected the failure recovery Is transmitted, the system switching back is completed (Fig. 33).

The time required from the detection of failure recovery to the completion of system switchback is that the failure recovery information takes one node within the transmission delay time (125 μsec × (number of nodes−1)) for one loop of the loop. It is the time obtained by adding the protection time and the time required from the reception of the information until the system switching back of the transmission path.

[Operation Corresponding to (7)] (FIGS. 11 to 38) As shown in FIG. 34, when the failure of both transmission paths that occurred in the section between the node devices SN1 and SN2 is recovered. Is
The 1-system transmission line receiving circuit 55 of SN1 and the 0-system transmission line receiving circuit 53 of SN2 detect recovery of the transmission line failure and notify the respective node control circuits 6.

Node control circuit 6 for SN1 and SN2
Instructs the 0-system and 1-system transmission path interfaces 50 and 51 to stop transmission of transmission path failure information, and instructs the system switching circuit 71 to cancel loop back after the protection time has elapsed. In SN1, since the 0-system transmission line failure information is still received, the 1-system transmission line 11 is set as the active system.

SN1 which received the instruction to stop the transmission of the fault information
The 1-system transmission line interface 51 of 1 stops the transmission of the 1-system transmission line fault information to the adjacent node MN, and transmits the SDH frame having 00h in the 1-system transmission line fault information area in the SOH ( However, when the failure information is received from another node, it is relayed). Also, the 0-system transmission line interface 50 of SN2 stops sending 0-system transmission line fault information to the adjacent node SN3, and sends an SDH frame with 00h in the 0-system transmission line fault information area in the SOH. It is sent (however, when the failure information is received from another node, it is relayed) (FIG. 35).

M which has received the system 1 transmission line fault recovery information (00h: no fault) from SN1 through the system 1 transmission line 11
N relays this to SN5 through the 1-system transmission line 11. Since the MN has still received the 0-system transmission line failure information, the 1-system transmission line 11 is switched to the active system after the protection time has elapsed, based on FIG.

Further, SN3, which has received the 0-system transmission path failure recovery information from SN2 through the 0-system transmission path 10, relays this information to SN4 (FIG. 36).

Similarly, the failure recovery information is relayed one after another and transmitted to the farthest nodes SN4 and SN5 of SN1 and SN2 which have detected the failure recovery.

In SN4 and SN5, the 0-system transmission line interface 50 receives the 0-system transmission line failure recovery information, and the 1-system transmission line interface 51 receives the 1-system transmission line failure recovery information, so that the node control circuit 6 fails. Notify recovery. Upon receiving the failure recovery notification from the transmission path interfaces 50 and 51 of both systems, the node control circuit 6 performs an operation for returning the active system to the 0 system transmission path 10 based on FIG. At this time, S
In N4, since the 0-system transmission line 10 has already been used as the operating system, system switching back is not performed at this point, but SN5
Then, when only the 1-system transmission line failure recovery information is received,
Since the system has been switched to the 1-system transmission line 11, the operation to switch the active system back to the 0-system transmission line 10 is adopted (Fig.
37).

Similarly, the failure recovery information of the 0-system transmission line 10 and 1
In each node device that has received the failure recovery information of the system transmission line 11, the system 0 transmission line 10 is set as the active system. Thus, SN
1 and SN2, the information on the failure recovery is transmitted to SN1.
When the system is switched back at, the loop back cancellation is completed (Fig. 38).

The required time from the detection of failure recovery to the completion of loop back is the transmission delay time (125 μsec × (number of nodes-1)) for the failure recovery information to make one loop.
This is the time obtained by adding the protection time and the time required from the time when one node receives the failure recovery information until the system is switched back to the transmission path. Further, when the protection time is set to be equal to or longer than the failure recovery information transmission delay time, both systems' failure recovery information is transmitted to each node device before the protection time elapses. The control for switching and switching back to the 0-system transmission line 10 is eliminated.

As described above, in the transmission path control method of the embodiment, even if the transmission time is the longest, the information transfer for the loop control is completed within the time period in which the fault information or the fault recovery information goes around the LAN.

Further, when a failure occurs, the communication path is secured by the autonomous loop control of the SN.
Therefore, even when the communication between the MN and the SN is interrupted due to the occurrence of multiple failures, it is possible to continue the communication by forming a communication path connecting only the SNs by the loop control of the SN.

[0115]

As is apparent from the above description of the embodiments, the transmission line control system of the double loop type communication device of the present invention enables high speed loop control.

Further, it is possible to secure a communication path even between SNs where the communication path with the MN is interrupted due to the occurrence of a failure.

[Brief description of drawings]

FIG. 1 is an L for implementing a transmission path control system according to an embodiment of the present invention.
AN configuration diagram,

FIG. 2 is a block diagram of a node device that implements the same transmission line control method;

FIG. 3 is a diagram showing an inter-adjacent-node frame (a), a loop revolving frame (b), and a revolving frame mapping (c) in the adjacent frame, which are used in the same transmission path control system;

FIG. 4 is a diagram showing a failure information format used in the same transmission line control method;

FIG. 5 is a diagram showing a loop control algorithm in the transmission path control system;

FIG. 6 is a diagram showing a transmission algorithm of fault information in the transmission path control system;

FIG. 7 is a diagram showing an operation of a first stage of occurrence of a 0-system failure in the transmission path control system;

FIG. 8 is a diagram showing a second stage operation in the same system 0 failure occurrence;

FIG. 9 is a diagram showing an operation of a third stage of occurrence of the same 0 system failure;

FIG. 10 is a diagram showing an operation of a fourth stage of occurrence of 0-system failure,

FIG. 11 is a diagram showing an operation of a first stage of occurrence of a failure in both systems in the same transmission line control system;

FIG. 12 is a diagram showing a second stage operation of the same system failure occurrence;

FIG. 13 is a diagram showing an operation of a third stage of the occurrence of a failure in both systems,

FIG. 14 is a diagram showing the operation of the fourth stage of the occurrence of a failure in both systems,

FIG. 15 is a diagram showing an operation of a fifth stage of occurrence of a failure in both systems,

FIG. 16 is a diagram showing an operation of a sixth stage of occurrence of a failure in both systems,

FIG. 17 is a diagram showing an operation in a first stage when a 1-system failure occurs after a 0-system failure in the same transmission line control method;

FIG. 18 is a diagram showing an operation of a second stage when the same system 1 failure occurs;

FIG. 19 is a diagram showing an operation of a third stage when the same system 1 failure occurs;

FIG. 20 is a diagram showing a fourth-stage operation when the same system 1 failure occurs;

FIG. 21 is a diagram showing an operation in a first stage when a 0-system failure occurs after both system failures in the same transmission line control system;

FIG. 22 is a diagram showing a second-stage operation when the 0-system fault occurs,

FIG. 23 is a diagram showing an operation of a third stage when the 0-system fault occurs,

FIG. 24 is a diagram showing an operation of a first stage of node failure occurrence in the transmission path control system;

FIG. 25 is a diagram showing a second stage operation of the same node failure occurrence;

FIG. 26 is a diagram showing an operation of a third stage of the occurrence of the same node failure;

FIG. 27 is a diagram showing a fourth stage operation of the same node failure occurrence;

FIG. 28 is a diagram showing an operation in the fifth stage of the occurrence of the same node failure;

FIG. 29 is a diagram showing a sixth stage operation of the same node failure occurrence;

FIG. 30 is a diagram showing a first stage operation of system 0 failure recovery in the same transmission line control system;

FIG. 31 is a diagram showing a second stage operation of the system 0 failure recovery;

FIG. 32 is a diagram showing an operation of a third stage of the same system 0 failure recovery;

FIG. 33 is a diagram showing an operation of the fourth stage of the same system 0 failure recovery;

FIG. 34 is a diagram showing an operation of a first stage of recovery from a failure in both systems in the transmission path control system;

FIG. 35 is a diagram showing an operation of a second stage of recovery from both system failures;

FIG. 36 is a diagram showing an operation of a third stage of recovery from both system failures;

FIG. 37 is a diagram showing an operation of a fourth stage of recovery from both system failures;

FIG. 38 is a diagram showing an operation of a fifth stage of recovery from both system failures;

FIG. 39 is a configuration diagram of a LAN that implements a conventional transmission path control method,

FIG. 40 is a configuration diagram of a conventional node device,

FIG. 41 is a diagram showing a first-stage operation in which a 0-system failure occurs in a conventional transmission path control system;

FIG. 42 is a diagram showing a second stage operation of the 0-system failure occurrence;

FIG. 43 is a diagram showing an operation of a third stage of occurrence of 0-system failure,

FIG. 44 is a diagram showing an operation of the fourth stage of the 0 system failure occurrence;

FIG. 45 is a diagram showing an operation of the fifth stage of the 0-system failure occurrence;

FIG. 46 is a diagram showing an operation of the sixth stage of the 0 system failure occurrence;

FIG. 47 is a diagram showing a first-stage operation in which a failure occurs in both systems in a conventional transmission path control system;

FIG. 48 is a diagram showing a second stage operation in the same system failure occurrence;

FIG. 49 is a diagram showing the operation of the third stage of the occurrence of a failure in both systems,

FIG. 50 is a diagram showing an operation in the fourth stage of the occurrence of a failure in both systems,

FIG. 51 is a diagram showing an operation of a fifth stage of occurrence of a failure in both systems,

FIG. 52 is a diagram showing an operation of a sixth stage of occurrence of a failure in both systems,

FIG. 53 is a diagram showing an operation of a first stage of node failure occurrence in the conventional transmission path control method;

FIG. 54 is a diagram showing a second stage operation of the same node failure occurrence;

FIG. 55 is a diagram showing an operation of the third stage of the occurrence of the same node failure;

FIG. 56 is a diagram showing an operation in the fourth stage of the same node failure occurrence;

FIG. 57 is a diagram showing an operation in the fifth stage of the occurrence of the same node failure;

FIG. 58 is a diagram showing a sixth stage operation of the same node failure occurrence;

[Fig. 59] Fig. 59 is a diagram illustrating an operation when failures occur at a plurality of points in the conventional transmission path control method.

[Explanation of symbols]

 MN Master node device SN1 to SN5 Slave node device 10 0 system transmission line 11 1 system transmission line 2 Logical communication channel for user information 3 Logical communication channel for control information 30 0 system transmission line Control bus 31 1 system transmission line Control bus 4 Multiplexing control bus 50 0 system transmission line interface 51 1 system transmission line interface 52 0 system transmission line transmitting circuit 53 0 system transmission line receiving circuit 54 1 system transmission line transmitting circuit 55 1 system transmission line receiving circuit 6 node control Circuit 71 0 system / 1 system switching circuit 72 Multiplexing / demultiplexing circuit 8 Line interface 90 Maintenance terminal 91 Terminal

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Ken Tomioka 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd.

Claims (4)

[Claims] 1. A transmission line control method for a dual loop type communication device in which a plurality of node devices are connected by a double transmission line that transmits data in mutually opposite directions, wherein a failure occurs when the communication device fails. Of the fault and the node device that has detected the fault are transmitted from the node device, the fault information is sequentially transmitted to all the node devices, and the loop control according to the location of the fault is made to each node device. A transmission line control method for a double-loop communication device, which is characterized in that it is performed autonomously. 2. The transmission path control method for a dual loop communication device according to claim 1, wherein the node device that has detected the failure continues to send the failure information until the failure is recovered. 3. SDH for transmitting the fault information
2. A (synchronous digital hierarchy) SOH (section overhead) is used.
Alternatively, the transmission line control method of the double loop communication device according to the item 2. 4. In each node device, from the detection of the fault or the reception of the fault information to the start of the loop control,
4. The transmission path control method for a dual loop communication device according to claim 1, wherein the failure information is spaced at a time interval longer than a time required for one loop.