JP3423185B2 - Self-rescue network, transmission line switching method and transmission device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission path switching system in a transmission network. The present invention is particularly applicable to S
ONET or SDH (Synchronous Digital Hierarch)
y) It is useful when applied to a transmission path switching method, a transmission device, and a network configuration method suitable for a network.

[0002]

2. Description of the Related Art In recent years, in order to improve the reliability of line services, various types of transmission lines for relieving signals in the event of line failure (for example, accidental disconnection or deterioration of the transmission line, failure of a repeater, etc.) Switching schemes have been proposed.

For example, (1) 1: N type NPS in which a plurality of working transmission lines and protection transmission lines are arranged on the same route
(Nested Protection Switch
ing) network and its transmission line switching method (2)
A 4-fiber BLSR (Bidi) in which a plurality of transmission devices are connected in a ring shape by an active transmission line and a backup transmission line
regional Line Switching
Ring) and its transmission path switching system have been proposed. The former example is, for example, Nested Protection Switchin
g T1X1.5 / 90-132,1992 and Fiber N
network Service Survivable
The latter example is for example Bellcore SONET BLS
R Genetic Criteria GR-1230-CORE, 1993
Is.

FIG. 9 is a diagram for explaining a 1: N type NPS network. In FIG. 9, 101 to 104 are transmission devices. The example of FIG. 9 has the following connections. The working transmission line 105 is terminated by the transmission devices 101 and 102. On the other hand, the working transmission line 106 is connected to the transmission devices 102 and 103.
Terminated with. The working transmission lines 105 and 106 are the transmission device 1
In 02, it is combined using an add-drop device. The working transmission line 107 ends at the transmission devices 102 and 104. The working transmission line 107 is the transmission device 1
It is broadcast on 03.

On the other hand, the backup transmission lines 109 to 111 are shown by dotted lines in FIG. The backup transmission lines 109 to 111 are connected to all of the transmission devices 101 to 104, and are coupled by using the add / drop device 114 in each transmission device. Each transmission device has the ability to switch the transmission line, and in these transmission devices, the working transmission line and the protection transmission line can transmit signals bidirectionally.

In the 1: N type NPS network shown in FIG. 9, an add / drop device or a repeater device can be selected as a transmission device according to the needs of the working transmission line. As a result, the service flexibility of this N-type NPS network is improved. Further, since this network shares the backup transmission line with the N active transmission lines, it is excellent in economic efficiency. Furthermore, this network is also excellent in expanding the existing transmission lines. For example, the traffic between the transmission devices 101 and 103 (traffi
When c) is to be newly added, it is possible to easily add a working transmission line having a required capacity. That is, it is realized by terminating the transmission devices 101 and 103 and relaying the transmission device 102 like the working transmission line 108.

Now, with such a configuration, what kind of switching should be performed when a failure occurs will be described with reference to FIG. The switching method depends on the following three factors.
That is, these elements are (1) the position of the transmission path where the failure has occurred, (2) the importance of the failure, and (3) the order of occurrence.

In the case where the first failure of importance level 3 occurs on the working transmission line 105, this working transmission line is relieved by using the backup transmission line 109. In this case, the larger the value of the importance, the higher the priority of relief of the failure.

When a second failure of importance level 1 occurs on the working transmission line 106, the working transmission line is relieved by using the protection transmission line 110.

When a third failure of importance level 2 occurs on the working transmission path 108, the protection transmission paths 109 and 1
10 is required. However, in this example, the backup transmission lines 109 and 110 are already used. Here, when the importance of the backup transmission line is examined, the backup transmission line 109 has the importance level 3 and the backup transmission line 110 has the importance level 1. At this time, since the importance of the backup transmission path 109 is higher than the failure importance of the working transmission path 108, the working transmission path 108 is not relieved. At this time, the working transmission line 106 remains in the rescued state. Therefore, the transmission device which has detected the failure of the working transmission path 108 must know that the working transmission path 108 is rejected.

In the case where a fourth failure of importance level 2 occurs on the working transmission line 107, the protection transmission lines 110 and 1 are used.
11 is required, but the backup transmission line 110 has already been used. When the importance of the backup transmission line is examined, the backup transmission line 110 has a priority of 1, and the backup transmission line 110 has a lower importance than the working transmission line 107. Therefore, the backup transmission line 110 is used to rescue the working transmission line 107.
At this time, the fourth obstacle is relieved, but the second obstacle and the third obstacle are not relieved.

As described above, the transmission path switching judgment and the transmission path switching operation of the NPS network are performed by the transmission device in which the working transmission path is terminated. For this reason, the transmission device must know the information about the other transmission line whose working transmission line duplicately requests the backup transmission line. Therefore, switching control information is exchanged between each transmission device,
The suitability of the switching operation must be judged based on this.

The following various methods have been proposed in which this switching is executed by exchanging control information in the transmission device due to the SONET / SDH overhead.
They are (1) APS (Automatic Protection Switch)
ing) byte and DCC byte (T1X
1.5 / 90-132), and (2) APS byte and timer method (Fibre Network Se)
rive Survivability). Here, since the APS byte is used for exchanging control information for switching the transmission line in SONET / SDH, SONET / SD
It is a byte defined in H. APS bytes
It consists of bytes called K1 bytes and K2 bytes. The method of using the APS byte in point-to-point is described in, for example, "Bellcore GR-25.
3-CORE, Issue 1, December 1993 ”, chapter 5.

"T1" which is the first switching method described above
X1.5 / 90-132 "is a method of transmitting the importance of the working transmission path by using a plurality of DCC bytes, and performing optimal switching of the working transmission path by comparing the importance.

In addition, the second method of the above-mentioned switching, "Fibre Network Service Su"
“Rivability” is the following method. The transmission device that has detected the failure sends the K1 byte of the APS byte,
Wait for K2 byte response. When the target station receives the K1 byte, it determines that the backup transmission path has been secured, and transmits the K2 byte indicating a response. The sender is K who gave this response
When 2 bytes are received, the switching operation starts. If there is a highly important request on the way to the target station, K1
The byte does not reach the target station and the K2 byte that indicates the response is not sent. Therefore, the transmission device that has detected the failure determines that the switching operation is not performed due to the timeout.

FIG. 10 shows 4Five, which is one of the transmission methods.
It is a figure explaining r type BLSR. 11 in FIG.
5 to 118 are transmission devices. Working transmission lines 119-12
2 and the spare transmission lines 122 to 125 are connected on the ring. Each transmission device has a transmission line switching capability, and these transmission devices are adapted to transmit signals bidirectionally between the working transmission line and the backup transmission line.

The basic operation relating to the switching of the transmission line with respect to the line failure in the 4-fiber type BLSR will be described. In FIG. 10, when a failure occurs in the working transmission line 122, the spare transmission line 126 is used to rescue the signal. When a failure occurs in both the active transmission path 122 and the backup transmission path 126, the bypass route, which is a characteristic of the ring type, is used, that is, in the 4Fiber type BLSR transmission method, the backup transmission paths 123 to 125 are used. By doing so, the signal can be relieved. As described above, a characteristic of the ring type relief method is that two routes, clockwise and counterclockwise, can be selected. For this reason, 4 Fiber
For the type BLSR transmission method, conventionally, a method capable of high-speed switching using only the APS byte (GR-1230).
-CORE) has been proposed.

[0018]

Simultaneous Digital Hierarchy (SDH) has been standardized in order to enable high function / performance of networks, flexible multiplexing of various information, and multivendor of communication devices. SDH is transmitted on a frame-by-frame basis, and the overhead of the transmission frame is controlled by APS (Automatic) as a control signal for line switching as described above.
Protection Switching) bytes (K1 and K2 bytes) are allocated.

A of PTP (Point-to-Point) method and Ring method
The PS byte is standardized as shown in Table 1. In this way, line switching between linear and ring networks is realized.

However, the NPS type network has many lines.
Since it is a multi-node, the PS byte so far cannot be applied. Further, in the NPS method, since a plurality of working lines are assigned to one spare circuit, it is necessary to consider efficient relief against multiple failures.

The drawbacks of the conventionally proposed switching method for NPS networks will be described in more detail.

The first problem is that when the APS byte and the DCC are used, a plurality of DCCs are processed by one control unit, which is very complicated and requires a long switching decision time. Secondly, when the APS byte and the timer are used, there is a case where the signal which the sender responds to arrives and a case where the signal does not arrive. Therefore, the problem is that the speed is low and the reliability is low. In addition, all the working transmission lines and the protection transmission lines must pass through the same route, which limits the arrangement of transmission devices and the laying of transmission lines.

In addition, the previously proposed BL has been proposed.
SR has the following drawbacks. Since the BLSR is a 1: 1 system, it is necessary to install as many spare transmission lines as the transmission capacity of the working transmission line. Therefore, the capacity required for the maximum traffic span is required as the capacity of the entire ring. In FIG. 10, for example, when only the traffic between the transmission devices 114 and 115 has the maximum capacity value in the network, the working transmission path 118 only sets the transmission capacity of the defined optical fiber to the maximum value. Instead, it is necessary to construct the transmission line of the entire ring to its maximum capacity value. In this way, the capacity of the entire network must be increased in order to increase the traffic of a specific section. Therefore, the use efficiency and the economical efficiency of the transmission line are serious problems.

As described in detail above, in order to switch the NPS type network, the number of the working line and its priority, the output of the switching signal and the information of the target node are required, and the APS byte of the PTP system or the Ring system is required. If you try to implement switching with, the capacity will be insufficient.

[0025]

SUMMARY OF THE INVENTION An object of the present invention is to provide a network with a small spare ratio and a high-speed transmission path switching method, a transmission device used for the network, and a control method thereof. is there.

Next, the outline of the present invention will be briefly described, and then various embodiments of the present invention disclosed in the present specification will be described in detail.

(1) A typical self-relief network is as follows.

At least a transmission frame having a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices is used, and at least a transmission frame having overhead information is used. In the self-relief network for digital transmission, the transmission device has a memory unit that forms a network table that stores at least the connection status of the network and fault information, and the working transmission line has a fault. When it occurs, based on the information of the byte for automatic switching in the overhead of the transmission frame, switching control information related to the failure is exchanged between the transmission devices configuring the network, and the switching control information and the network Self-relief type characterized by being configured so as to switch the transmission path based on the information in the table Ttowaku.

(2) Further, it has the following form.

At least a transmission frame having at least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices and having overhead information is used. A self-rescue type network that performs digital phase transmission and performs frame phasing and stuff control by pointer replacement in digital transmission, wherein the transmission device has a network table that stores at least connection status and fault information of the network. A memory unit that configures the network, and based on information of a byte for automatic switching in the overhead of the transmission frame when a failure occurs in the working transmission path, the switching control information related to the failure configures the network. The switching control information and the network are exchanged between transmission devices. Self relief network, characterized in that the construction described switch the transmission path on the basis of the information over click table.

The basic idea of the present invention is to assign, to the APS byte, the number of the working line among these pieces of information, its priority, and the outgoing node number of the switching signal. Furthermore, a network table for storing the network connection status and failure information is prepared for each node. As a result, the working line number included in the received APS byte,
The target node can be identified from the source node number and the connection status of the network table.

Table 2 shows an example of the allocation status of the various information in the APS byte. Two types of information are assigned to each of the K1 byte and the K2 byte in the APS byte. For example, (1) priority and (2) working line number are assigned to the K1 byte. The K2 byte is assigned (1) outgoing node number and (2) switching state.

Further, in this method, the APS byte is used not only for the purpose of switching the line, but also for updating the information of the network table in another node, thereby realizing high-speed switching judgment. .

Next, the basic switching protocol of the present invention will be described.

FIG. 33 shows the most basic switching protocol. When a failure occurs on the working line # 1 at time T1, the node B detects the failure and issues a "switch request" to the node A.
To notify. After confirming that the protection line # 0 has been secured, the node A switches the transmission side and notifies the node B. Next, the node B switches between the transmitting side and the receiving side, and notifies the node A that the switching is completed. Node A also switches the receiving side, and at time T2, all switching is completed.

Next, a switching protocol for switching multiple failures according to the present invention will be described.

FIG. 34 shows an example of multiple failures. Lines # 1 (failure SD) and # 3 (failure SF) have already been salvaged using the protection line, and line S has a failure S.
Consider the case where F occurs. Here, the following two rules are defined. SF (signal failure) has a higher priority than SD (signal deterioration) (rule 1), and if the priorities are the same, switching of the line that has already been rescued is maintained (rule 2).

In the conventional switching method, the protection line between the nodes AB, which has relieved the line # 1, stops relieving the line # 1 according to the above rule 1. However, the protection line between the nodes BC remains to rescue the line # 3 according to the above Rule 2. As a result, neither the line # 1 nor the line # 2 can be repaired, and the backup line between the nodes AB is not effectively used.

According to the method of the present invention, the efficiency of use of the spare circuit is improved by exchanging newly generated fault information between the nodes while maintaining the current relief state.

In order to realize this method, in the present invention, in the APS byte, the number of the working line in which a new failure has occurred is assigned to the K1 byte. In addition, the priority of the working line that is currently being rescued and the priority of the working line that has newly failed are multiplexed into K1 bytes (for example, SF on SD in Table 2).

Further, SF which cannot be relieved has a lower priority than SD (Rule 3). The spare line between the nodes AB, which has rescued the line # 1 by exchanging fault information between the nodes AB using the multiplexing function of this method, maintains the rescue of the line # 1 according to Rule 3. Leave. As a result, line # 2 cannot be repaired, but line # 2
1 can be maintained, and the protection line between the nodes AB is effectively used.

Conventional switching methods are PTP type and Ring type.
The types were not compatible. According to the method of the present invention, even if the network shape is changed from linear to ring due to, for example, addition of a node, the network table (Net
All you have to do is update the work table). As described above, the self-relief system of the present invention can divert network operation software.

Further, in the case of multiple failures, the self-relief system of the present invention switches the protection line after confirming that the protection of the failure line is reliable, so that the protection line can be efficiently used for repair. Becomes

Further, since the self-relief system of the present invention inherits the 1: N switching which is the characteristic of the PTP system and the Ring switching which is the characteristic of the Ring system, more reliable switching is possible. Become.

The basics of the transmission path switching method of the self-relieving network described above are summarized as follows.

(1) At least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, wherein the transmission device is In the self-relief type network, which has a memory unit that configures a network table that stores at least network connection status and failure information, and performs digital transmission using at least a transmission frame having overhead information of the transmission frame, the active transmission A transmission path switching method for a self-relief network, comprising at least the following steps when a failure occurs in at least one path.

(A) A step in which the first transmission device that has detected the failure notifies a predetermined second transmission device of a transmission path switching request.

(B) A step in which the second transmission device, which has received the request for switching the transmission path, judges whether or not the backup transmission path corresponding to the switching request can be used, based on the information in the network table.

(C) If it is possible to determine whether or not the backup transmission path can be used, the second transmission device sets the switching to the backup transmission path and sets the switching. Notifying the first transmission device.

(D) The first transmission device that has received this switching setting performs transmission line switching setting to use the backup transmission line switched and set by the second transmission device, and this transmission is set. Notifying the second transmission device of the path switching setting.

(E) A step of performing a switching setting to the effect that the second transmission device, which has received the notification of the switching setting of the transmission line, uses the backup transmission line set to the switching of the first transmission device.

(2) In the step (B), when it is judged whether or not the spare transmission line can be used when at least one of the working transmission lines fails, the second transmission device However, the method further comprises the step of not performing the setting for switching to the backup transmission path and using it.
Transmission line switching method of self repair network that.

(3) At least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, wherein the transmission device is In the self-relief type network, which has a memory unit that configures a network table that stores at least network connection status and failure information, and performs digital transmission using at least a transmission frame having overhead information of the transmission frame, the active transmission A transmission path switching method for a self-relief network, comprising at least the following steps when a failure occurs in at least one path.

(A) A step in which the first transmission device that has detected the failure notifies the predetermined second transmission device of overhead information.

(B) A step in which the second transmission device having received the overhead information judges whether or not the backup transmission line corresponding to the received overhead information can be used, based on the information in the network table.

(C) The second transmission device sets the switching of the backup transmission line based on the determination as to whether or not the backup transmission line can be used, and the information on the setting of the transmission line is set to the first transmission line. Informing the transmitting device of.

(D) A step of rewriting the information stored in the network table with new information based on the judgment as to whether or not the backup transmission path can be used.

Next, the outline of a further detailed example of the invention disclosed in the present specification will be described.

The network of the present invention comprises K (K is an integer of 3 or more) transmission devices, (K-1) backup transmission lines connecting the transmission devices in the form of a chain, and the transmission devices. A network having a plurality of working transmission lines connected to each other and having an overhead in a transmission frame, and when a failure occurs in the working transmission line, all switching control information related to the failure is automatically included in the overhead of the transmission frame. The switching bytes are exchanged among all the transmission devices constituting the network, and the transmission path switching circuit is performed based on the switching control information.

The overhead of the transmission frame is an area for transferring the operation and maintenance information of the network. Also, the byte for automatic switching in this overhead is used to send and receive signals for controlling system switching between transmission terminal devices and to display alarm status in case of failure of a repeater or transmission medium of the transmission system. It is something.
In SONET or SDH networks, this byte for automatic switching is called an APS byte and is usually composed of two areas K1 and K2.

Therefore, the present invention is extremely useful when applied to a typical SONET or SDH network.

That is, a typical example of the network of the present invention is
From K (K is an integer of 3 or more) transmission devices, (K-1) backup transmission lines that connect the transmission devices in a chain shape, and a plurality of active transmission lines that connect the transmission devices. In the SONET or SDH network to be formed, when a failure occurs in the working transmission line, all the switching control information related to the failure is transmitted by the APS byte of the overhead of the SONET or SDH frame for all the transmissions constituting the network. The devices are exchanged and the transmission line is switched based on the switching control information.

Another embodiment of the present invention is the following Ri.
ng type.

It is composed of K (K is an integer of 3 or more) transmission devices, K backup transmission lines connecting the transmission devices in a ring shape, and a plurality of working transmission lines connecting the transmission devices.
A network having an overhead in a transmission frame and having at least three transmission lines connected to at least one of the transmission devices, the fault being generated when a fault occurs in the working or protection transmission lines. The switching control information regarding the above is exchanged among all the transmission devices constituting the network by the overhead automatic switching byte of the transmission frame, and the transmission path is switched based on the switching control information.

Therefore, the Ring type is also extremely useful when the present invention is applied to a typical SONET or SDH network.

Next, the transmission device of the present invention has the following configuration.

For example, K (K is an integer of 3 or more) transmission devices, K-1 backup transmission lines connecting the transmission devices in the form of a chain, and a plurality of active transmission lines connecting the transmission devices. A transmission device used in a network formed with a transmission line, the transmission device having an automatic transmission frame overhead for exchanging fault information with a transmission device adjacent to each transmission device via a backup transmission line. A transmission / reception unit for switching, a monitor unit for monitoring an abnormality of the working transmission line, a storage unit for a network table for storing data indicating a network configuration, and at least a transmission line switching operation determination and transmission It is provided with a processing unit for determining a byte for automatic switching.

The transmission path switching operation and the transmission automatic switching byte are determined based on the transmission path monitoring result of the monitor section and the reception automatic switching byte.

This transmission device is a typical SONET or S
It is extremely useful when applied to a DH network.

Further, the Ring type transmission device has the following configuration.

For example, K (K is an integer of 3 or more) transmission devices, K-1 backup transmission lines connecting the transmission devices in a ring shape , and a plurality of active transmission lines connecting the transmission devices. A transmission device used in a network formed by: an automatic switching byte transmission / reception unit for overhead of a transmission frame for exchanging fault information with a transmission device adjacent to each transmission device via a backup transmission path; A monitor unit for monitoring an abnormality of the working transmission line, a storage unit for a network table for storing data indicating the network configuration, a transmission line switching operation determination and a "transmission automatic switching byte" determination. It is provided with a processing unit for performing.

The operation for switching the transmission path and the "transmission automatic switching byte" are determined based on the transmission path monitoring result of the monitor section and the reception automatic switching byte.

This transmission device is a typical SONET or S
It is extremely useful when applied to a DH network.

Further, the data indicating the network configuration is assigned to the connection information set between the transmission devices of the working transmission line, the connection information set between the transmission devices of the standby transmission lines, the transmission device number, and the working transmission line. It includes a number and current fault information of the transmission line in the network.

Further, another aspect of the present invention is as follows.

It is formed from K (K is an integer of 3 or more) transmission devices, K backup transmission lines connecting the transmission devices in a ring shape, and a plurality of working transmission lines connecting the transmission devices.
A transmission device used in a SONET or SDH network in which at least one of the transmission devices is connected with three or more active transmission lines, and the transmission device is adjacent to each of the transmission devices via a backup transmission line. To provide an APS byte transmission / reception unit of SONET or SDH frame overhead for exchanging fault information, a monitor unit for monitoring abnormality of the working transmission line, and a network table for storing data indicating network configuration. And a processing unit that determines the transmission path switching operation and the transmission APS byte based on the transmission path monitoring result of the monitor unit and the received APS byte.

Further, the data indicating the network configuration is used for connection information provided between the transmission devices on the working transmission path, connection information provided between the transmission devices on the backup transmission path, a transmission device number, and a signal rescue on the working transmission path. It includes the path information of the backup transmission path to be used, the number assigned to the working transmission path, and the current failure information of the transmission path in the network.

In the transmission device of the present invention, the data indicating the network configuration is dynamically updated by the signal from the processing unit.

Next, various examples of the transmission path switching method of the present invention will be described.

An example of the transmission path switching method of the present invention is that K (K is an integer of 3 or more) transmission devices and K-1 backup transmission lines connecting the transmission devices in the form of a chain. A transmission line switching control method performed by a processing unit of a transmission device used in a network formed of a plurality of active transmission lines connecting the transmission device, wherein (1) a first step of analyzing the content of a received APS byte (2) Transmission A based on the analysis result
It comprises a second step of processing the PS byte, (3) a third step of updating the network table based on the analysis result, and (4) a fourth step of setting the transmission direction of the processed APS byte. is there.

Another example of the transmission path switching method of the present invention is K (K is an integer of 3 or more) transmission devices and K backup transmission lines connecting the transmission devices in a ring shape. Transmission path switching performed by a processing unit of a transmission apparatus used in a network that is formed of a plurality of active transmission paths connecting transmission apparatuses, and at least one of the transmission apparatuses is connected to three or more active transmission paths A control method, comprising: (1) reception APS
A first step of analyzing the contents of the bytes, (2) a second step of processing the transmitted APS bytes based on the analysis result, and (3) a third step of updating the network table based on the analysis result. (4) Processed APS
And a fourth step of setting the byte transmission direction.

Furthermore, an example of the transmission path switching control method according to the present invention is as follows. Hereinafter, description will be made based on the above two transmission path switching control methods.

(1) That is, in the above two transmission line switching control methods, the second step includes a step of generating a request signal which is a trigger for switching, and the fourth step is stored in a network table. It includes the step of setting the transmission direction of the request signal on the path used for relief based on the data.

An example of the transmission path switching control method according to the present invention is as follows.

(2) That is, in the two transmission path switching control methods, the second step includes a step of generating a status signal indicating a switching status, and the fourth step includes a network table. It includes the step of setting the transmission direction of the status signal on a path that is not used for rescue, based on the data stored in.

An example of the transmission path switching control method according to the present invention is as follows.

(3) That is, in the two transmission path switching control methods, the second step is a request signal indicating that the APS byte received in the first step is a switching trigger, and indicates a switching request. In addition, when it is determined that the transmission is addressed to the own station, the transmission device includes a step of generating an APS byte indicating a response to the switching request.

An example of the transmission path switching control method according to the present invention is as follows.

(4) That is, in the two transmission path switching control methods, the second step is that the APS byte received in the first step is a request signal indicating a switching trigger and a response to the switching request is sent. If it is determined that it is addressed to the own station, the transmission device includes a step of generating an APS byte indicating a protection request.

Further, an example of the transmission line switching control method according to the present invention is as follows.

(5) That is, in the two transmission path switching control methods, the second step is a request signal indicating that the APS byte received in the first step is a switching trigger, and indicates a protection request. In addition, when it is determined that the transmission is addressed to the own station, the transmission device includes a step of generating an APS byte indicating a protection request.

An example of the transmission path switching control method according to the present invention is as follows.

(6) That is, in the above-mentioned two transmission path switching control methods, the second step is the step of receiving the A signal received in the first step when the own transmission apparatus is performing the switching.
This includes a step of regenerating the APS byte when it is determined that the PS byte is not addressed to the own station and is a request signal indicating a switching trigger.

Further, an example of the transmission line switching control method according to the present invention is as follows.

(7) That is, in the two transmission path switching control methods, the second step is based on the data stored in the network table when the transmission device detects or receives a plurality of pieces of failure information. , And generating an APS byte in which the plurality of pieces of failure information are multiplexed.

An example of the transmission path switching control method according to the present invention is as follows.

(8) That is, in the above two transmission path switching control methods, the second step is a request signal indicating that the APS byte received in the first step is not addressed to itself and a switching trigger. Yes, when the backup transmission path on the opposite side to the receiving direction is already used for relief of another fault, and it is determined that the importance of the received APS byte is higher than that of the rescued fault. The information indicating that the switching of the working transmission line whose fault has been relieved has been completed and the received A
And a step of setting the transmission direction of the generated APS byte to the opposite side of the reception direction of the received APS byte. including.

(9) Furthermore, in the second step, the APS byte received in the first step is a request signal indicating that the APS byte is not addressed to itself and a switching trigger. If it is determined that the backup transmission line has already been used to rescue another failure and the importance of the received APS byte is lower than or equal to the importance of the rescued failure, switching rejection is rejected. Including the step of generating the included APS bytes, and the fourth step includes the step of setting the transmission direction of the generated APS bytes to the receiving side of the received APS bytes.

An example of the transmission path switching control method according to the present invention is as follows.

(10) That is, in the two transmission path switching control methods, the second step is a request signal indicating that the APS byte received in the first step is not addressed to itself and a switching trigger is indicated. Yes, the backup transmission line on the opposite side of the receiving direction is already used for relief of other failures,
If it is determined that the importance of the received APS byte is higher than the importance of the rescued failure, the information indicating that the switching of the working transmission path in which the failure has been rescued has been completed, and the received APS byte Switching refusal is included in the step of generating a multiplexed APS byte, and the fourth step includes the step of setting the transmission direction of the generated APS byte to the opposite side of the reception direction of the received APS byte. It is a waste.

Further, an example of the transmission line switching control method according to the present invention is as follows.

(11) That is, in the above two transmission path switching control methods, it is determined in the second step that the APS byte received in the first step indicates switching refusal and is addressed to the own station. In the case of the above, the third step lowers the importance of the request that causes the switching refusal,
It includes the step of updating the data in the network table.

Further, an example of the transmission path switching control method according to the present invention is as follows.

(12) That is, in the two transmission path switching control methods, it is determined in the third step that the APS byte received in the first step indicates switching refusal and is addressed to the own station. In this case, it is judged whether or not there is a path different from the path of the backup transmission line used for the relief stored in the network table, and when there is a different path, the working data stored in the network table is used. It includes the step of updating the path information of the backup transmission line used for signal rescue of the transmission line.

Further, an example of the transmission line switching control method according to the present invention is as follows.

(13) That is, in the above two transmission path switching control methods, in the second step, when the own transmission device is not switched, the APS byte received in the first step is the local station. If it is determined that the request signal is not addressed to and is a request signal indicating a switching trigger, the step of transferring the APS byte as a transmission APS byte without changing the APS byte is included.

An example of the transmission path switching control method according to the present invention is as follows.

(14) That is, in the two transmission path switching control methods, the second step is performed when the APS byte received in the first step is determined to be a status signal indicating a switching status. Includes a step of transferring the received APS byte as a transmission APS byte without changing the received APS byte.

Furthermore, the transmission line switching method of the present invention includes the number of the working transmission line having the highest importance in the APS byte, the number of the signal transmission station, and the switching response state of the transmission station.

[0110]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the self-relieving network, the transmission device, and the transmission path switching method of the present invention will be described with reference to FIGS. 1 to 8 and 11 to FIG.

The basic idea of the present invention is that when a failure occurs in the backup transmission line or the working transmission line, the switching control information is exchanged between all the transmission devices constituting the network by the APS byte, and this switching control information is exchanged. It is a self-relief network that switches transmission lines based on it. The present specification discloses the shape of the network, a transmission device used for the network, and a transmission path switching control method. The APS
Bytes are K1 and K2 bytes defined in the overhead area of the frame used in SONET / SDH. These are used for switching control.

FIG. 1 is a main block diagram of a transmission apparatus showing an embodiment of the present invention. This transmission device incorporates a signal rescue device. In the network according to the present invention, each transmission device in the network has the basic configuration shown in FIG. The control unit 6 is composed of hardware, and has a processing unit 1 and a network table 2 therein. The working transmission line 10 is terminated in the working transmission line terminating device 8. The monitor unit 4 is provided in the working transmission line terminating device 8.

On the other hand, the backup transmission line 9 is terminated in the backup transmission line terminating device 7. The backup transmission line terminating device 7 has a monitor unit 4 and an APS byte transmitting / receiving unit 3. Only the backup system has the APS byte transmitting / receiving unit. FIG. 1 shows the flow of only control information which is a sub signal.

Each transmission device has a switching unit 5 for switching the main signal.

The monitor section 4 monitors the working transmission line and, when detecting a failure, sends the failure information to the processing section 1 by a monitor signal. The APS byte transmitting / receiving unit 3 receives the APS byte transmitted from another transmission device and sends it to the processing unit 1. The processing unit 1 analyzes both the received APS byte and the signal from the monitor unit and outputs the network table (Netwo
The data stored in the rk table) is read by the NT response signal and the APS byte is processed. This APS byte processing is for allocating bit patterns and the like. As a result, the processing unit 2 sends the processed APS byte to the APS byte transmitting / receiving unit 3. Further, the data in the network table is dynamically updated by the NT processing signal.

A 1: N type transmission system having a plurality of transmission devices has a plurality of working transmission lines. Therefore, when failures occur simultaneously in a plurality of working transmission lines of the transmission system, there are two types of failures. The first type of fault is a state in which no fault has occurred redundantly in the path of one backup transmission line used for relief. This is hereinafter referred to as "independent disorder". The second type is a state in which a failure is duplicated in one backup transmission line. This is referred to as "overlap failure"
Called.

When the monitor unit 4 of the transmission device detects an independent failure, the monitor unit 4 sends the detected failure information of the working transmission line to the processing unit 1. When the processing unit 1 receives the failure information from the monitor unit 4, the processing unit 1 queries the network table and confirms the current status. Then, based on the result of this confirmation, the working transmission path to be switched is determined, and the APS byte indicating the switching request is generated. The generated APS byte is sent to the APS byte transmitter.

On the other hand, the transmission apparatus which has detected the failure sends the APS byte containing the switching request to the target station and waits for the switching response. The response of this signal is omitted in FIG.

In the case of a transmission device that requires switching, the processing unit 1 analyzes the content from the received APS byte. Then, as a result of this analysis, when the processing unit 2 receives the switching request, the processing unit 2 switches the transmission data, generates the APS byte including the response to the switching request, and generates the APS byte by the generated APS byte. Send to the transmitter.

The processing unit 1 analyzes the content from the received APS byte, and when the switching response is received, the APS byte including the protection request for completing the switching of the transmission / reception data and maintaining the switching completed state is obtained. Generate and this generated APS
Send the bytes to the APS byte transmitter.

The processing section 1 analyzes the contents from the received APS byte. When the processing unit 2 receives the protection request, the switching of the received data is completed, and the APS byte including the response to the protection request is generated. Then, the processing unit 1 sends the generated APS byte to the APS byte transmission unit. Thus, the basic switching operation among the processing unit 1, the monitor unit 4, and the APS byte transmitting / receiving unit is completed.

Further, in the transmission device in which the failure has already been repaired, the processing section 2, when receiving the failure information, makes an inquiry to the network table. Then, when the importance of the received switching request is higher than the importance of the failure for which the switching has already been completed, the processing unit 2 determines the working transmission path to be switched. The information switching failure is relieved working path has been completed, the information of the switching request of the APS bytes received is to generate APS bytes containing the duplicate switching request multiplexed APS byte transmission section 3 Send to. If the importance of the received APS byte switching request is less than or equal to the importance of the rescued failure, the processing unit 1 includes A
A PS byte is generated and sent to the APS byte transmitter 3. At this time, the APS is not changed at this stage.
Process bytes.

Further, in the transmission device irrelevant to switching, the processing unit 2 speeds up the processing time by transferring without processing the APS byte.

FIG. 2 is a diagram showing a basic signal sequence flow. First, the types of APS bytes will be described.

Signals of the APS byte are roughly classified into "request signal" and "status signal". The request signal is a signal that serves as a switching trigger. This signal is sent on the request path of the backup transmission path used for the relief of the failure, and is used for determining the transmission path switching of the transmission device. The status signal is sent on the status path of the backup transmission line that is not used for the relief of the failure, and notifies other transmission devices of the failure information and the switching information. By doing so, network information is shared by all transmission devices.

The sequence flow of the request signal that serves as a switching trigger will be described. FIG. 2 shows a working transmission line terminated by the transmission device A and the transmission device B.

Consider a case where a fault occurs in this working transmission line and the transmission device B detects this fault. The transmission device B sends a switching request to the transmission device A. Upon receiving the switching request, the transmission device A switches the transmission data and sends a response to the switching request to the transmission device B. Upon receiving the switching response, the transmission device B switches the transmission / reception data and sends a protection request for maintaining the switching completed state to the transmission device A. The transmission device A that has received the protection request switches the received data and sends a response to the protection request to the transmission device B. Thus, the transmission device A
And a transmission device B completes a series of switching operations.

FIG. 3 is a diagram showing an example of the contents of information carried in the APS byte. APS byte is so-called "K
It has two bytes, "1 byte" and "K2 byte". These K1 and K2 bytes are SONET / SDH
It has a 2-byte area added as a redundant signal of the frame used in.

The K1 byte contains "Sw Priority" indicating the information on the degree of importance of the fault condition and "Channel ID" indicating the working transmission line number of the fault. K2
The byte is "Source ID" indicating the transmitting device.
And information "r / s signal" indicating whether the signal type of the K1 and K2 bytes is a request signal or a status signal, and "Status" indicating the current switching state of the transmission apparatus.

FIG. 4 is a detailed block diagram corresponding to the schematic block diagram of FIG. The processing unit 1 includes a fault comparison / determination circuit 1
1, target station comparison / determination circuit 12, signal determination circuit 13, state determination circuit 14, APS byte processing unit 15, transmission setting unit 1
6, AND gate circuits (AND gate curcuit) 17 to 20, and an OR gate circuit (OR gate curcuit) 21.

The fault comparison / determination circuit 11 receives the received APS
Extracting the severity of the occurrence failure from the K1 byte in the byte,
It has a function of comparing with a plurality of predetermined failure patterns and determining whether there is a matching pan turn. If there is a matching pattern as a result of this comparison / determination, A
Is output. The output A is the AND gate circuit 1
It is led to the input terminals up to 7, 18, 19 and 20.

The target station comparison / determination circuit 12 receives the received AP
From the K2 byte in the S byte, the failure channel
It has a function of extracting the lID and determining whether or not it is the target station from the data stored in the network table. As a result of this determination, if it is the target station, B is output, and if it is not the target station, b is output. The output B is guided to the input end of the AND gate circuit 17. The output b is guided to the input terminals of the AND gate circuits 18 and 19.

The signal judging circuit 13 has a function of judging from the K2 byte in the received APS byte whether the APS byte indicates a request signal or a status signal. If the result of this determination is a request signal, C is output, and if it is a status signal, c is output. The output C is the AND gate circuit 1
It is led to the input ends of 7, 18, 19 and 20. Output c
Is guided to the input terminal of the AND gate circuit 20. The state determination circuit 14 has a function of determining, based on the data stored in the network table 2, whether or not the switching has already been completed in order to relieve the failure in its own transmission device. If the result of this determination is that switching has already been performed, D is output to recreate the received APS byte, and if no switching has been performed, d is output to transfer the received APS byte. . The output D is guided to the input end of the AND gate circuit 18. The output d is led to the input end of the AND gate circuit 19.

The APS byte processing section 15 has a function of processing an APS byte. This APS byte processing unit 15
Can perform any of the response operation, the PT operation, and the re-creation operation based on the received APS byte and the information of the network table.

The response operation is an operation executed by the transmission device related to the switching operation performed by the request signal. P
The T operation is an operation in which a request signal or a status signal is transferred. When the transmission device is performing switching, the re-creation operation is performed by transmitting the switching request while maintaining the switching state to the protection request for repairing the fault and the switching request for the newly generated fault. This is the operation of multiplexing or separating into bytes. The PT operation and the recreating operation are operations performed by the transmission device that are unrelated to the switching operation performed by the switching request for the newly generated failure.

The response operation is an operation triggered by the AND gate 17 under the following conditions. The conditions are (1) that the failure comparison determination circuit 11 matches the failure state with the failure pattern, (2) that the target station determination circuit determines that the APS byte is the target station, and (3) that the signal determination circuit There are three conditions for determining that the signal is a request signal.

The PT (pass-through) operation has the following two operations.

In the case of the first condition, AND gate 18
After that, the operation is triggered by the OR gate circuit 21. The first condition is (1) fault comparison / determination circuit 11
The fault condition matches the storage pattern in (2), the target station determination circuit determines that the APS byte is not addressed to itself, (3) the signal determination circuit determines that it is a request signal, and (4) ) It is when the state determination circuit determines that switching has not been performed in the own transmission device.

In the case of the second condition, it is triggered by the OR gate circuit 20 via the AND gate 20. The second condition is when the fault comparison and determination circuit 11 determines that the fault state matches the storage pattern and the signal determination circuit determines that it is a status signal.

The re-creating operation means AN under the following conditions:
This is an operation triggered by the D gate 19. This condition means (1) that the fault state in the fault comparison and determination circuit 11 matches the fault pattern, and (2) that the target station determination circuit is AP.
This is when it is determined that the S byte is not addressed to its own station, (3) the signal determination circuit determines that it is a request signal, and (4) the state determination circuit determines that the rebuild operation has been executed.

A processed by the APS byte processing unit 15
The PS byte is sent to the APS byte transmission setting unit 16.
The APS byte transmission setting unit 16 uses the APS byte processing unit 1
The transmission path information and the APS byte are sent to the APS byte transmission / reception section 3 by setting the path for transmission by referring to the command from 5 and the data stored in the network table.

The processing section 1 can also be configured by hardware as described above. Further, the processing unit 1 uses a CPU,
It can be realized by software. 5, FIG. 6, FIG. 7 and FIG. 8 are operation flows of the embodiment of the present invention when the processing unit 1 is realized by software.

<Operation Flow in Processing Unit> The steps in FIG. 5 are as follows. In addition, what is shown in brackets such as (S1) is
Each step of FIG. 5 is shown.

(S1): SW Priority indicating the degree of importance of the failure state of the received APS byte signal is compared with a plurality of predetermined failure patterns, and it is determined whether or not any of them matches.

(S2): If the failure pattern matches any one of a plurality of predetermined failure patterns,
It is determined whether the received APS byte signal indicates a request signal.

(S3): If it indicates a request signal, Channel with K1 byte of APS byte
Based on the ID, the path information of the working transmission path stored in the network table is referenced to determine whether or not it is addressed to the own station.

(S4): When the APS byte indicates the address of the own station, it is notified as a response operation.

(S5): On the other hand, in step (S3), when the APS byte does not indicate the address of the own station, the own station repairs another failure and determines whether or not the switching is being performed.

(S6): If it is determined that the switching is being performed, the re-creating operation is notified (S8). When notified as a recreating operation, the APS byte is recreated.
FIG. 7 shows the operation flow.

(S7): On the other hand, in step (S5), when the switching is not performed in the own station, the PT operation is notified. If the received APS byte signal does not indicate the request signal in S2, the PT operation is notified. (S8): When a response operation instruction is received, switching is performed and an APS byte indicating a response is generated. FIG. 6 shows the operation flow.

As the PT operation, the APS byte processing unit that has received the notification transfers the APS byte to the APS byte transmission unit according to the operation flow of FIG.

The APS byte is processed according to the notified operation method.

(S9): The processed APS byte is based on the path information obtained from the network table, and the request signal is on the request path used for signal rescue, and the status signal is not used for signal rescue. The setting is made on the path.

(S10): In the APS byte transmitter 3, the APS byte is inserted in the overhead and transmitted.

<Response Operation> Details of the “response operation” will be described. FIG. 6 shows an operation flow of the above-mentioned response operation. The parentheses such as (S1) indicate each step in FIG.

In FIG. 6, the status bus and the request bus indicate backup transmission lines between the nodes.

The ASP byte part of the transmission device B is (S4)
The response operation notification is sent by the device and the response operation is performed.

First, the transmission device in which a failure has been detected (for example, refer to the transmission device B in FIG. 6) has the importance of the failure of the request path which is a path used when data is protected. It is determined whether or not the importance is the highest (step S41). The judgment result of the failure level is sent to the APS byte section.

Then, the following two request signals are generated in response to the judgment result of the degree of failure (S4).

(1) When the failure has the highest importance and the request path has a protection request, a request signal indicating a multiplexed duplicate switching request is generated.

(2) Further, when the degree of importance of the failure is the highest and there is no protection request in the request path, a request signal indicating a non-multiplexed independent switching request is generated.

Further, the APS processing section of the transmission apparatus B generates the above-mentioned two types of "request signal" and also generates a "status signal" for notifying the status. Then, to another transmission device related to the switching, that is, to the opposite station (hereinafter, in the explanation of the transmission and reception of this signal, the transmission apparatus A is referred to as the “opposition” in the meaning of the transmission apparatus opposite to the transmission apparatus B). Inform about these situations. This request signal is set so as to be transmitted to a request path used for data rescue, and then the request signal other than these transmission devices (that is, the transmission devices A and B).
(Except for APS byte). The status signal is set so as to be transmitted to a status path which is not used for data rescue, and then sent to the APS byte transceiver of the game. Then, the game is waited for, that is, in the case of this example, a response from the transmission apparatus A is waited for (S45).

At the game, it is judged whether or not the degree of importance of the failure of the received APS byte is the highest in the request path (S43). The result of this determination is sent to the APS byte processing unit. The APS byte processing unit that has received the determination result,
When the importance of the failure is the highest, it is decided to switch the data to the backup transmission line, and a "request signal" and a "status signal" indicating a response to the switching request are generated. At this time, the ASP byte transmitting / receiving unit of the game notifies the transmission device that has detected the failure (that is, the transmission device B) of the response to the switching request by the Status information (S44). In addition, A
The SP byte processing unit sets the "request signal" to be sent to the request path and the "status signal" to be sent to the status path.
It is sent to the S-byte transmitting / receiving unit 3. Then, the ASP byte transmitting / receiving unit of the transmission device A waits for a response from the transmission device (transmission device B) that has detected the failure (S48).

When the APS transmitter / receiver of the transmission device (transmission device B) that has detected a failure receives a "switching response" indicating that switching is possible from the opposite station, the data of the working transmission path in which the failure has been detected is reserved. The switching to the transmission line is completed. Then, the APS byte processing unit of the transmission device B generates a request signal indicating a protection request and a status signal. Further, the AS of the transmission device B
The P-byte transmitting / receiving unit notifies the player (transmission device A) of the "protection request" by the Status information (S47).

On the other hand, when the transmission device B receives a "switch refusal" indicating that switching is impossible from the game, the transmission device B
Changes the request path used for protection of the network table, and then tries the response operation flow described above from the first step S41. If there is no possible path used for all the rescue, the transmission device B changes the priority of the occurrence failure to low priority (S46).

In the game (transmission apparatus A), when the failure detection transmission apparatus receives the notification that the switching has been completed, the data switching is completed, and a request signal indicating a response to the protection request and a status signal are generated. A protection request is notified to the game (transmission device A) by the Status information (S49).

<Recreating Operation in APS Byte Processing Unit> FIG. 7 shows a flow of the above-mentioned recreating operation.

Upon receipt of the "recreating operation notification" as shown in step S6 of FIG. 7, the reproducing operation is performed. First, it is determined whether the importance of the received APS byte is the highest in the switching request (S61). In this determination, if the received APS byte has the highest importance in the switching request, the ASP byte processing unit determines whether or not there is a protection request on the opposite side of the received direction of the received APS byte. (S62).

On the other hand, when the received APS byte is the independent switching request, it is determined whether the importance of the received APS byte is higher than the protection request (S63). Then, when the importance of the received APS byte is higher than that of the protection request, the APS byte processing unit generates a "duplication switching request" (S65). If the importance of the received APS byte is not higher than the protection request,
The APS byte processing unit generates "switch refusal" (S
66).

On the other hand, in step S62, if the received APS byte does not have a "protection request", an "independent switching request" is generated (S64).

When "switch refusal" is received,
In the same way as the re-creating operation of "Switch request", "Switch reject"
And "protection request" are multiplexed and separated.

<PT (Pass Through) Operation> FIG. 8 shows PT
It is a flow of (pass-through) operation. Step S of FIG.
As shown in 7, the APS byte processing unit receives the “PT operation notification” and performs the PT operation.

First, the transmission device determines whether or not the received APS byte indicates a "request signal" (S71).

When the received APS byte indicates a request signal, it is determined whether or not the "request signal" has the highest importance (S82). At this time, when it is determined that the "request signal" cannot be switched by the "status signal" from another transmission device, the importance is considered to be lower than the "status signal". If the failure comparison / determination circuit determines that the “request signal” is of high importance, the ASP byte processing unit determines that the “request signal” is high.
Is unchanged and is transmitted as the APS byte, the APS of the game
The data is transferred to the byte transmitting / receiving unit (S84).

On the other hand, if the received APS byte does not indicate a "request signal" in step S71 of FIG. 8, it is determined whether or not there is a request signal of high importance (S).
83).

At this time, when it is determined that the failure of the request signal cannot be repaired by the status signal of another failure for which the repair is already performed, the importance of the request signal Is considered less important than the situation signal. In other cases, it is considered that the importance of the request signal is higher than that of the situation signal. If there is no "request signal" of high importance, the "status signal" is transferred unchanged to the APS byte transmission / reception unit as a transmission APS byte (S84).

<Network for Rescue from Self-Relief and Other Matters> FIG. 11 shows an example of a network capable of relieving self-relief by using all APS bytes for the switching control information according to the present invention.

The illustrated self-relief network is provided with first to fifth transmission devices 200, 201, 202, 203 and 204, and each of these transmission devices comprises a series of chains, that is, one transmission line with four backup transmission lines. It is connected in a chain. Here, the first to fifth transmission devices 200 to 204 are the transmission device A, the transmission device B, the transmission device C, the transmission device D, and the transmission device E, respectively. Working transmission lines 205, 206, 2
The current transmission line number of 09 and 210 is set to 1, and the current transmission line 2
The working transmission line number of 07 and 210 is 2.

The active transmission lines 205 to 210 are connected as shown in the figure. Each transmission device has a transmission path switching capability. Further, in these transmission devices, the working transmission line and the protection transmission line are adapted to transmit signals bidirectionally.

When a failure occurs in the network having such a configuration, (1) the failed transmission line and (2)
Depending on the importance of the transmission path and (3) the order of occurrence,
What kind of switching is performed will be described.

When the first failure of importance level 3 occurs on the working transmission path 206, this working transmission path 206
Are relieved using the backup transmission line 212. The higher the importance value, the higher the priority.

When a second failure of importance level 1 occurs on the working transmission line 209, the working transmission line 209 is relieved using the backup transmission line 213. The APS byte in the rescued state has the structure shown in FIG. This APS byte contains "Sw Priori
ty ”is the degree of importance,“ ChannelID ”is the number assigned to the current transmission path, and“ SourceID ”is the transmission device number that originated the transmission,“ Status (Status (Status)
"s information)" includes each information indicating the switching state of the transmission device.

As a result of performing the switching procedure as described above, the "request signal" indicating the protection request for the working transmission path 206 is transmitted and received on the protection transmission path 212. Backup transmission line 2
As a result of performing the switching procedure as described above, the "request signal" 13 indicating the protection request for the working transmission path 209 is also transmitted and received. Further, a “status signal” indicating a protection request for the active transmission path 206, which is transmitted from the transmission apparatus B, is transmitted to the backup transmission path 211. A “status signal” indicating a protection request for the active transmission path 209, which is transmitted from the transmission device D, is transmitted to the backup transmission path 214. The transmission device that has received the signal updates the data stored in the network table to a new state.

Consider a case where a third fault having a degree of importance of 2 further occurs in the working transmission path 208 in a state where these two faults have been relieved. When the transmission device that has detected this failure is the transmission device E, the transmission device E first
The APS byte indicating "independent switching request" in the "request signal" is transmitted to the transmission device D (S42). Transmission device D
Re-creates the "independent switching request" and the "protection request" for the working transmission path 209 as an "overlapping switching request" (S65). At this time, since the switching request and the protection request are duplicated, the APS byte area SwPr
The combination of two importance levels is multiplexed into iority as one signal. For ChannelID, 2 is entered in the active transmission path number that is a switching request, and SourceID and Status information include information on the protection status of the active transmission path 209, and these are transmitted from the transmission apparatus D to the transmission apparatus C.

The transmission device C cannot secure the backup transmission line 212 for the third failure, and therefore returns "switch refusal" to the transmission device D (S66). At this time, since the switching refusal for the active transmission path 208 and the protection request for the active transmission path 209 are duplicated, the combination of the two importance levels is multiplexed as one signal in the APS byte area, SwPriority. ChannelID
Shows the working transmission line number 2 which is refusal of switching, and Source
The eID and Status information includes information on the protection status of the working transmission path 209. The transmission device D informs the transmission device E of this "switching refusal" by using the APS byte indicating the switching refusal. The transmission device E thus knows that switching is not possible (S64).

As a result, the relief of the third fault is rejected and the optimal relief as a network is executed without hindering the relief of the second fault.

FIG. 12 shows a ring-shaped network. In this example, a spare transmission line capable of performing self-relief using the APS byte according to the present invention is connected in a ring shape. The illustrated self-relief network includes first to fifth transmission devices 200, 201, 202, 204 and 205, and these transmission devices are connected in a ring shape by five backup transmission lines. Here, the first to fifth transmission devices 200 to 205 are referred to as the transmission device A, the transmission device B, the transmission device C, the transmission device D, and the transmission device E, respectively, and the working transmission lines 205, 206, 209, and 210.
The current transmission line number of 1 and the current transmission lines 207, 210
The working transmission line number of is set to 2.

The active transmission lines 205 to 210 are connected as shown in the figure. Each transmission device has a transmission line switching ability, and these transmission devices are adapted to transmit signals bidirectionally through the working transmission line and the backup transmission line.

In the ring-shaped network, there are two methods of selecting the backup transmission line used when the faulty working transmission line is rescued: clockwise and counterclockwise.

First, as a first method of setting a backup transmission line, a backup transmission line used when the working transmission line is abnormal is set in advance in the network table. For example, when the same failure as in FIG. 11 occurs, it is possible to repair the third failure if the backup transmission paths are set to 211 and 215. That is, the selection of the backup transmission path is set in advance so that the redundancy rate of the backup transmission path becomes small.

As a method for setting the second backup transmission line, the priorities of the paths of the clockwise and counterclockwise backup transmission lines are set in advance, and switching is attempted from the path with the higher priority and the relief is performed. It is to improve the rate. For example,
When the same failure as in FIG. 11 occurs, the path with the higher priority for the third failure is assumed to be the backup transmission path 212, 213,
Even at 214, when the transmission device E receives the switching refusal, the transmission device E refers to the path information in the network table and refers to the backup transmission line 2 which is the second priority path.
Attempts switching at 11 and 215.

Further, in the present invention, since the status signal is used, a certain transmission device can know the switching information in another transmission device. For example, it is assumed that when the first failure occurs on the working transmission path 207, the protection transmission paths 211 and 212 are used for relief. In this state, when the second fault further occurs on the working transmission line 205, the transmission device A receives the status signal of the first fault from the transmission device C via the protection transmission lines 213, 214 and 215. . Therefore, the transmission apparatus A refers to the path information in the network table, and the backup transmission paths 213, 214, and 21 which are paths with a low priority used for relief of the first failure.
It can be confirmed that 5 can also be used. Then, if the transmission device A determines from this confirmation that it is possible to rescue the first and second faults by using the path, the transmission device A switches the first faulty path. Is performed without instantaneous interruption, the backup transmission lines 213, 214, and 215 are used for repair, and the second fault is repaired by using the backup transmission line 211.

Further, in this example, when a failure occurs in the backup transmission line, and when a failure occurs in the working transmission line that uses the backup transmission line, the relief is performed by a different path that does not include the backup transmission line. It can be carried out. For example, if a failure has already occurred in the backup transmission path 212 and a failure has occurred in the current transmission path 208 included in the first priority path for the backup transmission path, the transmission device E receives the rejection and the network With reference to the path information in the table, switching is attempted on the backup transmission paths 211 and 215, which are the paths having the second priority.

<Signal Sequence of APS Bytes in Transmission Line Switching> Next, in order to further explain the transmission line switching method of the present invention, a signal time series of APS bytes will be described.

The networks of FIGS. 13 to 30 are provided with first to seventh transmission devices 301 to 307, which are connected by backup transmission lines. Here, the first to seventh transmission devices 301 to 307 are individually transmitted to the transmission devices A, B, C, D,
Let E, F and G be the active transmission line numbers of the active transmission lines 308 and 310 and 1 be the active transmission line number of the active transmission line 309. Each transmission device has a transmission path switching capability.

FIG. 13 is a network diagram for explaining the transmission line switching method of the present invention when a failure which is the importance of SF occurs in the active transmission line 308, and FIGS. 14 and 15 show the network of FIG. It is a basic time chart of an APS byte.

FIG. 14 shows a basic APS byte from the occurrence of a failure to the completion of switching, and FIG. 15 shows a time chart of the APS byte when the switching state is restored.

In FIG. 14, no fault has occurred at time T0, which is the initial state. At time T1, the transmission apparatus E detects the fault SF on the active transmission line 1, and sends the status signal 8b to the opposite side with the request signal 8a, which is a switching request, directed to C. When the transmission device C receives the switching request, it starts switching, sends the request signal 9a, which is a switching response, to E, and sends the status signal 9b to the opposite side. When the transmission device E receives the switching response, the switching is completed and the request signal 1 which is a protection request is transmitted.
0a is directed to E, and the status signal 10b which is a protection request is transmitted to the opposite side. When the transmission device C receives the protection request, the switching is completed and the protection signal E
To the other side, the situation signal 11b, which is a protection request, is transmitted to the other side. The transmission device that has received the request signal or the status signal updates the network table based on the information of the APS byte. This allows transmission devices A, B, F and G
Also, it is known that the transmission path switching by the SF is performed between the CEs of the active transmission path 1, and the high-speed switching determination can be performed when a new failure occurs.

In FIG. 15, when the fault is cleared at time T2, the WTR signal is transmitted from E and the response is received, and the switching is held for a certain period of time. At time T3, when the set time comes, the switching cancellation signal 14a is transmitted, and all switching is canceled.

16 to 20 illustrate a transmission path switching method in the case of multiple failures in which two failures in which switching is not completed overlap.

FIG. 16 is a network diagram (part 1) for explaining the transmission path switching method of the present invention when multiple failures occur.
Is. 17 and 18 are time charts (No. 1) of the APS byte in the network of FIG. 16, FIG. 17 is a time chart when a failure occurs in the working transmission path 309, and FIG. 18 is a time chart when a failure in the working transmission path 309 is recovered. is there.

In FIG. 17, since the data in the network table is updated by the status signal 8b, the transmission apparatus F recognizes that it cannot switch the transmission path of the working transmission path 309 whose importance is SD. In this case, the APS byte is not transmitted.

In FIG. 18, the transmission device F receives the WTR signal and thereby knows that the failure of the working transmission line 308 has been recovered. As a result, it is shown that the active transmission path 309 whose importance is SD is being rescued.

FIG. 19 is a network diagram (part 2) explaining the transmission path switching method of the present invention when multiple failures occur.
20 is a time chart (No. 2) of the APS byte in FIG.

In FIG. 20, when both of the switching are not completed, the switching request of the active transmission path 309 whose importance is SF is determined to be the switching request of the active transmission path 308 without using the duplicate request by the priority judgment. On the other hand, it is shown that switching is performed while performing preemption. As a result, the working transmission line 309 is repaired.

21 to 28 are a network diagram and an APS byte time chart at the time of multiple failures in which a failure occurs in the working transmission path 309 while the working transmission path 308 is being repaired.

In the following example, the working transmission line with the working transmission line number 308 is repaired.

FIG. 21 is a network diagram (part 3) for explaining the transmission path switching method of the present invention when multiple failures occur.
22 is a time chart (No. 3) of the APS byte in FIG.

In FIG. 22, in order to try the switching request of the active transmission path 2 whose importance is SF, the transmission devices D and E are tried.
Request signal 11 which is a duplicate switching request between
It is shown that switching is performed after confirming whether or not the necessary backup transmission path is usable. As a result, working transmission line 3
09 relief is being done.

FIG. 23 is a network diagram (part 4) for explaining the transmission path switching method of the present invention when multiple failures occur.
24 is a time chart (No. 4) of the APS byte in FIG. 23.

In FIG. 24, since the data in the network table of the transmission device F is updated by the status signal 8b, the transmission device F has a working transmission path 309 whose importance is SD.
It is recognized that the APS byte of the working transmission path 309 is not transmitted, since it is recognized that the transmission path switching of the above is not possible.

FIG. 25 is a network diagram (No. 5) for explaining the transmission path switching method of the present invention when multiple failures occur.
26 is a time chart (No. 5) of the APS byte in FIG. 25.

In FIG. 26, a switching request is made between the transmission devices C and D by using the request signal 10a, which is a duplicate switching request, in order to try the switching request of the working transmission path 309 whose importance is SF. Is shown. As a result, the working transmission line 309 is repaired.

FIG. 27 is a network diagram (No. 6) for explaining the transmission line switching method according to the present invention when multiple failures occur.
28 is a time chart (No. 6) of the APS byte in FIG. 27.

In FIG. 28, as a result of the priority determination made by the transmission device D, the AP having the low-priority working transmission line number 309
It shows that S bytes are not transmitted.

FIGS. 29 and 30 show the case where the active transmission line 310 and the active transmission line 308 have already been repaired for a failure of SF importance and a failure of SD importance, respectively. In 309, a transmission path switching method when a failure of importance SF occurs is described.

FIG. 29 is a network diagram (No. 7) for explaining the transmission path switching method of the present invention, and FIG. 30 is a time chart (No. 7) of the APS byte in FIG.

In order to try the switching request of the active transmission path 309 whose importance is SF, the request signal 13 which is a duplicate switching request is used between the transmission devices C and E. The transmission device C, which has been notified of the failure information by the status signal of the working transmission line 310, rejects the switching request. The transmission device C notifies the transmission device E that it is impossible to rescue the working transmission line 309 by using the request signal 14 that is the double switching refusal. The transmission device E that has received this request signal notifies the transmission device F that the rescue of the working transmission line 309 is impossible by using the status signal 15 which is a duplicate switching refusal. It is also possible to withdraw the rejected signal for a certain period of time. As a result, the working transmission line 308 is being relieved although the failure is less important than the working transmission line 309.

As described above according to the embodiments, the present invention makes it possible to switch a faulty transmission line at high speed and with high reliability. This depends on the following factors.

(1) The working transmission line can be laid according to the traffic demand.

(2) There is an advantage that the spare ratio is made small by sharing the spare transmission line with a plurality of working transmission lines, and the economical efficiency and the use efficiency of the working transmission line are improved.

(3) Furthermore, the APS byte is used for exchanging the switching control information between the transmission devices.

<Rule> Finally, the rule used in the self-relief network of the present invention will be described in detail.
Although the rules which are not directly related to the transmission path switching system of the present invention are included, these rules are not applicable to the present network, for example, SO.
It is useful for controlling the transmission itself in the NET network or SDH network.

[0224] In addition, the above <APS in transmission path switching
The signal sequence of bytes> is, of course, controlled according to the following rules.

First, the "switching instruction" is defined. The command for switching the transmission line is composed of an "external start command" and an "automatic start command". The external activation command is "OS (Operating System)" or "W
It is input by the S (Work Station) interface mainly for maintenance. The "automatic activation command" monitors the actual transmission line and is activated by a physically occurring failure.

The "external activation command" is activated by the OS or WS interface and input to the transmission device. The processing unit of the transmission device activates the command according to the priority determination. The external start command can change the switching state, and it cannot confirm whether they are local start or remote start. Therefore, if they do not need to be transmitted in APS bytes, they need not be defined in APS bytes. Such commands are sent using the section DCC.

An external start command to be started from the OS or WS interface to the transmission device without using the APS byte will be described.

Clear: This command is an external start command. Clear the WTR command of the transmission device indicated by the instruction. NR code (No Requests)
By using t), the following external activation command can be cleared.

[0229] When switching the span between certain transmission devices excessively or when suppressing switching of the working transmission line having data that does not need to perform transmission line switching, the following 2
One instruction is valid. Since these commands are not time constrained, they are sent using the section DCC.

Lockout of working
channel: This command prohibits access to the backup transmission line of the specified working transmission line by invalidating the switching request of the transmission device. If the working transmission path has already been switched, the switching is canceled regardless of the reason for the working transmission path. If no other request is valid, an NR request is sent.

Lockout of protecti
on-all spans: This command prohibits access to all backup transmission lines. If the working transmission path has already been switched, the switching is canceled regardless of the reason for the working transmission path. This command is not supported by APS byte. Therefore, this command must be sent to each of the transmitters and the lockout
Used synonymously with the to of protection request.

The external start command in which the APS byte is used will be described.

Lockout of protecti
on-span: This command prohibits the use of the designated backup transmission line even if the transmission line switching is valid. If the data of a certain working transmission line has already used the protection transmission line, this command switches the data back to the working transmission line.

Forced switch-spa
n: This command executes switching from the designated working transmission line to the protection transmission line. If there is no failure in the backup transmission line and there is no more important request, this command is executed regardless of the state of the backup transmission line.

Manual switch-spa
n: This command executes switching from the designated working transmission line to the protection transmission line. If the backup transmission line is SD
If a bit rate lower than (Signal Degrade) is detected and there is no request of equal importance or of high importance (including failure of the backup transmission line), this command is executed.

In the network of the present invention, the exerciser function is indispensable because many working transmission lines share the backup transmission line. To detect silent failures (ie failures that cannot be detected automatically), the network of the present invention exercises with the APS function.

[Exercise-span]: This command executes the exercise of switching to the specified working transmission line without actually switching. This command is executed without affecting the data on the working transmission path.

The "automatic start command" is started by monitoring all working transmission lines and protection transmission lines and finding a failure. Then, the processing unit activates the command according to the priority logic. The above-mentioned switching procedure is also the automatic start command.

The transmission device uses the following "first br".
"idge request" and "overlap br"
types of bridges of "idge request"
Automatically issue request, WTR and NR.

First bridge requests
t is SignalFailure-P in its importance.
rotation (SF-P) and Signal F
airure (SF), Signal Degrad
e (SD).

Overlap bridge req
est is, for its importance, Signal Failure
e on Signal Degrade (SF o
nSD). These bridge requests
t is transmitted from the transmission device to the transmission device.

Next, the sequence flow of the automatic start command will be described.

SF request is a request issued to protect data affected by a severe failure. SD request, on the other hand, is a request issued for a minor failure. The request is a "bridge request" for the detected request path.
For the situation path, "bridge status
"tus" is issued. The Bridge request is a request signal such as a switching request or a protection request. b
The ridge status is a status signal such as a switching request or a protection request.

The intermediate transmission device has its bridge re
It is confirmed by referring to the network table whether the quest is addressed to the own transmission device. When there is another request even if it is not addressed to the own transmission device, priority evaluation is performed to determine whether to pass through or reject the bridge request, and the next signal is issued.

In the target transmission device, the bridge req
When it is determined that all the backup transmission paths are available when uest is received, switching is started, and bridged indication, that is, a response to the switching request is returned by the status information. In addition to monitoring for failures and degradations, the transmission equipment must also receive notification of whether the switching attempt was successful. This is because in the case of the network of the present invention, point-to-point
This is because, unlike t, even if the detected current transmission path has a high severity, the transmission device that has detected the failure cannot determine whether or not it is protected.

[0246] The transmission device is a bridge request.
If you issue the other bridge request
If the importance is high, preempt will be performed.
However, if there is a transmission device that has already switched in the required backup transmission line, the request is passed while maintaining the switching, and whether all the required backup transmission lines are available or not Must be judged.

Overlap bridge req
est is a bridge req issued when another request passes through the protection transmission line already used for switching.
It is east. Necessary protection at this time
Start the preemption after securing the line.
However, if the priority of this bridge request is low priority, it is rejected and the bridge reject is rejected.
Will be replied. The transmission device which has received this switching refusal determines that this bridge request has the lowest priority.
When this signal is received for a certain period of time, the emission is stopped until the recurrence request signal is received.

WTR request: This command is a request for preventing oscillating switching between the protection transmission line and the working transmission line. The WTR request is issued when the restoration threshold of the working transmission line is satisfied. The WTR is issued only after the recovery of the SF or SD failure and is not used after the external start command. If the SF is cleared and the BER meets the recovery threshold, the transmission device is SD
Do not enter the condition. Also, this signal is considered to have the highest importance for a certain period of time, and becomes a reissue request signal to notify the entire network of the situation.

SF is LOS (Loss of of optical signal).
Signal) and LOF (Loss of Fra)
me) and a line BER that triggers when it falls below a preset bit error rate threshold, and other hard hard faults that can be protected.

Signal failure of P
protection (SFP): A request used when the backup transmission line detects a failure. When the backup transmission line detects a failure, it is necessary to perform lockout of protection on the backup transmission line affected by the failure. At this time, the APS byte is locked
Uses the same code as to of protection.

Signal failure (S
F): A request used when there is a hard failure in the working transmission line and no other failure is protected on the request path.

Signal Degrade of P
protection (SDP): a request used when the protection transmission line detects signal deterioration.

Signal degradation (S
D): SD is a soft fault detected when the set BER threshold is exceeded. It is used to detect signal degradation as a basis for repair and repair. This is a request used when there is signal deterioration in the working transmission line and it overlaps with the relief of other failures.

Signal failure on S
internal degradation (SFon SD): When there is a failure in the working transmission line and SD is protected on the request path, it is overlap bridge request.
This is the request used as est.

Reject of Signal fa
illure on Signal degrade
(R-SF on SD): Used as an overlap bridge reject when SD is protected on the requested path because there is a failure on the working transmission path but the necessary backup transmission path cannot be used and switching is rejected. Request.

The functional rules are summarized as follows.

<Summary of Functional Rules> (Rule 1) The clear command deletes all external start commands in the designated transmission device. No Request
The st code is used for exchanging information of clear command between transmission devices.

(Rule 2) The clear command also clears the WTR state.

(Rule 3) The clear command which should clear all external start commands is the operation
It is received from the system (OS) by the transmission device that has activated the request.

[0260] In Table 1, Lockout of
protection, Forced switch,
Signal failure, Signal failure
lure on Signal degrade, Si
general degrade, Reject of Si
general failure on Signal de
grade, Manual switch, Wait
to restore, Exerciser, Nor
The assignment of the command “request” is shown.

[0261]

[Table 1]

(Activation Rule of K1 Byte and K2 Byte) Next, the activation rule of K1 byte and K2 byte which are contents of the APS byte will be described. When multiple failures occur, protection channel conflicts occur. At this time, it is necessary to perform priority switching indicating the degree of importance for request allocation and transmission path switching. In SONET, the K1 and K2 bytes of STS-1 # 1 are used for the switching operation. The first 4 of K1
Bits are used to indicate the importance of APS bytes. Bits 4 to 8 of K1 represent the working transmission line number having the highest importance of the working transmission line which can use the protection transmission line. Bits 1 to 4 of K2 indicate the number of the transmission device issuing the current APS byte. Bit 5 of K1 requires K1 and K2 bytes
It indicates whether the signal is a t signal or a status signal. Bits 6 to 8 of K1 indicate the status information, and indicate the switching state of the transmission device which issued the APS byte.

All transmission devices are idle in the initial state.
Send the APS byte in state. Unless the APS byte is addressed to the own transmission device and there is a request of higher importance, the requests are transmitted one after another. When the target transmission device receives it, it performs a switching operation and returns a response signal. If rejected on the way, a rejection signal is returned. The transmission device that issued the request waits for the response and performs the next operation. If the response is not received within a certain period of time, the request is withdrawn.

Generally, after confirming the completion of the bridge for switching the data on the transmitting side so as to minimize the data fragmentation, the switch for switching the data on the receiving side is completed. However, when the span is completely cut off and the switching request is received from the target station and the crossing K bytes are reached, the data has already been cut off.
Hing.

The rules for the K1 and K2 bytes are as follows.

(Rule 4) Network of the present invention The transmission path switching supports bidirectional communication.

(Rule 5) All network switching of the present invention is reversible.

(Rule 6) All network switching of the present invention returns from the backup transmission line to the original working transmission line only.

(Rule 7) When SF or SD is cleared by the transmission device, the transmission device has a higher priority bri.
When neither the reception of the dge request, the detection of another failure, nor the operation of the external activation request occurs, the WTR state is entered and the state is continued for an appropriate timeout period.

(Rule 8) The 1-4 bits of K1 carry the importance of the switching request according to the importance provided in Table 1, or the importance of the switching request and the importance of protection switching.

(Rule 9) The transmission device uses the active transmission line and the null.
It has the ability to determine the degree of importance of l channel (for detecting a backup transmission line), and the default importance is the lowest.

Table 1 shows SF requests on the backup transmission line.
They are shown in descending order except that t is more important than FS.

(Rule 10) The 5-8 bits of K1 are K
It carries the number of the working transmission line indicating the importance of the 1-4 bit switching request of 1.

Table 2 shows how to allocate 5 to 8 bits of the K1 byte.

[0275]

[Table 2]

(Rule 11) bri in a transmission device for switching
The number of the working transmission path used for the dge request is always terminated by the transmission device. When SF is detected in the working transmission path, SF is issued, and when SD is detected, SD is issued.

The K2 byte is allocated as provided in Table 3.

[0278]

[Table 3]

(Rule 12) All switching operations are K2
Reflected by upgrading bits 6-8 of the byte.

(Rule 13) The transmission device sends out the default APS code as shown in Table 4 until the proper APS signal transmission suitable for the current state of the network of the present invention can be performed.

(Rule 14) The transmission device sends the default APS code until it obtains the path connection information and the transmission device number information from the network table of the present invention.

(Rule 16) If the processing unit detects a failure and there is no transmission failure for the line while the diagnosis is being executed or while exercising, the bridge request is not activated.

Table 4 shows an example of the default APS code.

[0284]

[Table 4]

The above request means that the failure of the transmission line switching function is different from the transmission line switching of the present invention. For example, the number of a working transmission line that does not exist is transmitted.

(Three types of transmission device states) The APS code inserted in the K1 and K2 bytes by the transmission device defines the following three types of transmission device states according to the state of the transmission device. "Idle state", "Switchi
ng state "," Pass-throughs "
Tate ”.

The state of the transmission device changes depending on the situation, and becomes a steady state when a series of switching operations is completed. First, the steady state will be described.

A. "Idle State": Table 5 shows I
The K1 byte and the K2 byte of the dle state are shown.

[0289]

[Table 5]

(Rule 16) The transmission device is a bridger
When the request or the bridge status is not detected, generated, or pass-through, the idle state is set.

(Rule 17) All transmission devices in the idle state state terminate the K1 and K2 bytes in both directions.

B. "Switching Stat
e ”: Switching State has 4 sub-states depending on whether the switching operation is completed.
There are types. Sw # 0 # 0, Sw # 0 # N, S
w # N # 0, Sw # N # M (N and M are non-zero integers)
Is. In this, the first working transmission line number indicates the receiving direction side of the APS byte, and the second working transmission line number indicates the opposite side to the receiving direction. Table 6 shows the types of Sw states.

[0293]

[Table 6]

(Rule 19) first bridge
The transmission device that detects, issues, or terminates the request is in the Switching State.

(Rule 20) first bridge
The following states exist depending on the request switching state.

Common rules among the four Sw-state substates will be described. Table 7 shows K1 bytes and K2 bytes of Switching State.

[0297]

[Table 7]

(Rule 21) switching station
The transmission device at te issues the APS byte shown in FIG.

B-1 Sw # 0 # M: (Rule 21) The transmission device is the first bridger.
The request (automatic activation or external activation) can be detected, emitted or terminated. Also, the transmission device is
The verlap request can be terminated.

(Rule 22) bridge not addressed to own transmission device
When a ge request is received, it is regarded as detection in the state viewed from the side opposite to the receiving direction.

(Rule 23) The idle status code or the bridged status code is issued.

(Rule 25) switching The transmitting device follows the following rules for bridged request,
bridged status, bridged r
Issue an eject.

(1) When a fault is detected in the working transmission line which terminates in the transmission device, or when a bridge request from another transmission device is detected, priority determination is made and the working transmission line is protected. When there are no more important requests due to the backup transmission line, first br
You can issue the idge request.

(2) When the transmission device with the bridge request channel number terminates at the transmission device, the transmission device in the switching state switches to the request path on the request path side.
& Bridged status indicat
Ion is issued and the bridge status is displayed on the side of the situation path.
Issue tus.

Another bridge request on the context path
When est exists, bridge status
Do not emit.

(3) Bridge re addressed to another transmission device
If the quest is rejected, it will issue a bridge reject if it is not the originating transmitter.

(4) Bridge generated by own transmission device
bri until the response to the request
The contents of dge request do not change.

(5) When the bridge reject is received for a certain period of time, the bridge re related to it is received.
Stop issuing the quest.

B-2 Sw # N # M: (Rule 25) The transmission device has completed switching.
It is possible to detect, issue, and terminate an e request. In addition, overlaplap bridgeequ
Est can be detected, emitted, or terminated.

(Rule 26) bridge not addressed to own transmission device
When a ge request is received, it is regarded as detection from the opposite reception direction.

(Rule 27) switched & br
Issued the idged status indication code.

(Rule 28) switching The transmitting device complies with the bridged request according to the following rules.
bridged status, bridged
Issue a reject.

(1) When a fault in the span of the working transmission line terminating in the transmission device is detected, or when a bridge request from another transmission device is detected, priority determination is performed and the overlap bridge is determined.
You can issue a request. Detected bridg
When e request is addressed to another transmission device, channel N
If it is less than the importance of, it will be rejected.

(2) When the transmission device having the request channel number of the bridge request is terminated at the transmission device, the transmission device in the switching state has the switched & bridged status of the bridge request on the request path side.
Indication is issued and br is sent to the situation path side.
Issue the idge status.

However, another bridge is added on the situation path.
When the request exists, the bridge sta
Do not emit tus.

(3) Bridge re addressed to another transmission device
When the request is rejected, the bridge reject is issued when the device is not the transmitting / receiving device.

(4) overla issued by the own transmission device
Until there is a response to the p bridge request, the overlap bridge request
The contents of st do not change.

(5) When the bridge reject is received for a certain period of time, the bridge re related to it is received.
Stop issuing the quest.

(Rule 30) Switching station
The transmission device, which is te, refers to the requested channel number and the information in the network map of the present invention, and bridg
Specifies whether the e request is terminated.

(Rule 30) Default from request path
Switchings that receive the APS code
The state transmission device does not change its signal transmission or perform any operation related to that path until it receives an appropriate APS code.

C. Pass-Through Sta
te: (Rule 31) first bridge requests
When t is not terminated, the transmission device is Pass-t.
It is in a rough state.

(Rule 32) There are the following two types in the Pass-through state depending on the state of the first bridge request.

Table 8 shows the types of pass-through states. KPT (K byte pass-through)
h) allows the APS byte to pass, and PPT (Protec
Tionpass-through) allows only data on the protection transmission path to pass through.

[0324]

[Table 8]

KPT: (Rule 33) A transmission device in this state is a bridge
request (automatic start or external start), bri
dge reject, or bridge stat
can pass us.

PPT: (Rule 34) The transmitting device in this state is first b
It is allowed to pass through the backup transmission line of the "ridge request".

(Rule 35) The transmission device in this state is b
ridge request (automatic start or external start), or overlaplap bridge request
est detected and overlap bridge re
You can issue a quest.

(Rule 36) The transmission device in this state is b
The edge reject can be terminated.

Next, transition rules between the three states will be described.

(Rules for Transition Between Three States) (Rule 37) For all transitions between states of three transmission devices, change of input K bytes or detection of faulty K bytes, external start command, transmission device fault detection. The situation triggers.

(Rule 38) For K bytes, the same three consecutive frames are received as valid.

(Rule 39) The transmission device uses the APS con
Does not change the current state unless a trigger is received from the controller.

(Rule 40) Information contained in bits 1 to 4 of K1 byte is a bridge request in the following cases:
Considered as t.

Bits 1-4 of the K1 byte are first
In the bridge request, if bit 5 of the K2 byte indicates the request signal.

Bits 1-4 of the K1 byte are overl
In the case of ap bridge request, bit 5 of the K2 byte indicates request signal.

(Rule 41) The information contained in bits 1-4 of the K1 byte is the bridge status in the following cases:
Is regarded as

Bits 1 to 4 of the K1 byte are bridged
e request, bit 5 of K2 byte is sta
If it indicates tus signal.

(Rule 42) bridge requests
In t, the backup transmission path for the t is other bridger.
Coexistence is allowed as long as it does not overlap with the backup transmission path for the request.

(Rule 43) bridge requests
In t, the backup transmission path for the t is other bridger.
When it overlaps with the backup transmission line for the request, the first bridge whose switching operation has already been completed
If there is a request, it will be overlap bri
It becomes dge request. Fir with outgoing transmission device
Even in the case of the st bridge request, the first bridge may be changed depending on the state in the middle of the span.
e request and overlap bridge
It can also be a request.

(Rule 44) overlap bridge
e request is not protected in that state. Be sure to use the first bridge request
Be protected after.

(Rule 45) bridge requests
In t, the backup transmission path for the t is other bridger.
When the switching operation is not completed in either of the bridge requests when overlapping with the backup transmission line for the request, the first brig is shown in FIG.
It can be preempted as a dge request.

(Rule 46) bridge requests
t is the bridge s regardless of the importance of each
preempt status. bridge sta
tus does not preempt the bridge request.

(Rule 47) bridge status
When the coexistence is not allowed, can preempt the emission from the transmission device of the bridge request of lower importance.

(Rule 48) The network switching operation of the present invention is started and released only by request signal.

(Rule 49) All local requests
st (SF, SD condition, localWTR, external request, etc.) is the local request that has the highest priority than the table showing the importance.
st is determined. If they are of the same importance, the one with the smaller current transmission line number is given priority.

(Rule 50) When the WTR is normally timed out, it becomes NR-null channel. The WTR state is not restored when preempted.

(Rule 51) When the external start request is cleared, the NR-null channel state should be entered. (It does not enter the WTR state.) A. Transition Between the
Idle and Pass-Through St
ates: (Rule 52) The transmission device in idle state
Bridge req not terminated with own transmission device
When receiving uest or bridge status from a certain direction, the transmission device enters the KPT.

(Rule 53) The transmission device in the PPT is K1.
Byte bits 1-4 No Request and K2
6-8 idle indicati on bits of byte
When receiving the oncode from both directions, the transmission device returns from the KPT to the idle state.

B. Transition Betwe
en the Idle and Switching
States: (Rule 55) The transition from Idle state to Sw # 0 # M is triggered by one of the following situations.

A bridge request in which K bytes are terminated from No Request to the transmission device.
Change to st ・ Detection of fault that can be protected by the transmission device ・ Input of external start command that can switch protection to the transmission device (Rule 56) The transmission device in Sw # 0 # M has bits 1-4 of K1 byte No Request, bit 5-8 null channel, K2 byte bit 6-8 idle indication cod
When receiving e from both directions, the transmission device uses Sw # 0.
Return to idle state from #M. bridg
When the condition by e request is cleared,
The transmission device in which the bridge request is inserted releases the switch to request the request.
To cancel.

(Rule 57) switching station
When the transmission device at te transits to the idle state, it transits in the following three steps.

(1) switch for generating a request
The ching transmission device (tail-end) first releases the switch, and the K1-byte bit 1-
No Request of 4 with bit 6 of K2 byte
-8 Bridged indication cod
Insert e.

(2) No Request and Bridg
Upon receiving the ed indication code, the transmission device that has detected the failure releases the bridge and the switch, and the idle code is inserted in both directions. s
The release of the watch is received on the request path.

(3) When the transmission device which has detected the failure receives the idle code on the request path, the bridge
ge is released and idle code is inserted in both directions.

(Rule 58) Bridge between SF and SD
For the request and the bridge status, the transmission device sets the bri after the WTR time period.
Release the dge and issue a release signal.

C. Transition Betwe
en the Pass-Through and S
Witching States: (Rule 59) The transmission device in Sw # 0 # M has higher importance and is not terminated by the own transmission device.
When preempted by ge request, KP
Enter T. (Rule 60) When the transmission device at the PT receives a Bridged code or a bridge request addressed to the own transmission device having higher importance, Sw
Enter # N # M.

(Rule 61) A transmission device in Sw is bridged to another transmission device having a higher degree of importance.
When the code or the bridge request is received, the KPT is entered.

D. Transition Withi
n Switching States: (Rule 62) A transmission device that is Sw # N # M is bri to a transmission line that overlaps with its own transmission device.
Bridge with higher importance than dge request
When receiving a request, the status is Sw # 0 # M
And the bridge request of lower importance
st is a bridge request of higher importance
Preempted by.

(Rule 63) When Sw # 0 # M detects a bridge request of higher importance destined for the transmission device, it is preempted by the bridge request.

(Rule 64) Bridg issued by own transmission device
The switching state is upgraded upon receipt of the e request response.

(Rule 65) A transmission device that is Sw # 0 # M is switched & bridged to its own transmission device.
d indication, or bridged i
When the Ndication is received, switching to Sw # N # M is completed.

(Rule 66) When a fault condition affecting only one span is cleared by one transmission device, that transmission device enters the WTR and unless the following conditions are satisfied:
It will continue for the appropriate timeout time.

Bridge with higher importance than WTR
The request is received.

Other faults are detected.

The external start command becomes valid.

(Rule 67) Although a request for bridging was made, but a transmission device which has not actually detected a failure receives the WTR code, the transmission device sends out the WTR.

E. Transition Withi
n Pass-Through States Sta
te: (Rule 68) When a request release signal is received by the transmission device in PPT, it becomes KPT. Both sides of the KPT transmission device are switched & bridged indi
It becomes PPT when receiving the ration code

[0368]

According to the present invention, a working transmission line can be laid according to a traffic demand, and a spare transmission line is shared by a plurality of working transmission lines to reduce the spare ratio. As a result, there is an advantage that the economical efficiency and the use efficiency of the current transmission line are improved. Furthermore, by using the APS byte for exchanging the switching control information between the transmission devices, it is possible to switch at high speed and with high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of the present invention. Figure 2
Is the basic signal flow of the present invention. FIG. 3 is a structural example of an APS byte according to the present invention. FIG. 4 is a block diagram showing an embodiment of the present invention. FIG. 5 is a basic operation flow of the present invention. FIG. 6 is an operation flow of the response of the present invention. FIG. 7 is an operation flow of re-creation of the present invention. FIG. 8 is an operation flow of the PT of the present invention. FIG. 9 is an example of the configuration of NPS. FIG. 10 shows a configuration example of the BSLR. FIG. 11 is a configuration example (1) of a salvageable network according to the present invention. FIG. 12 is a configuration example (part 2) of the salvageable network according to the present invention. FIG. 13 is a diagram showing an example of occurrence of an independent failure in the network. FIG. 14 is a diagram showing a time chart of the APS byte when an independent failure occurs. FIG. 15 is a diagram showing a time chart of APS bytes at the time of recovery from an independent failure. FIG. 16 is a diagram showing an example (1) of occurrence of multiple failures in the network. FIG. 17 is a diagram showing a time chart (No. 1) of the APS byte when multiple failures occur. FIG. 18 is a diagram showing a time chart (No. 1) of the APS byte at the time of recovery from multiple failures. FIG. 19 is a diagram showing an example (part 2) of occurrence of multiple failures in the network. FIG. 20 is a diagram showing a time chart (No. 2) of the APS byte when multiple failures occur. FIG. 21 is a diagram showing an example (3) of occurrence of multiple failures in the network. FIG. 22 is a time chart (No. 3) of the APS byte when multiple failures occur. FIG. 23 is a diagram showing an example (part 4) of occurrence of multiple failures in the network. FIG. 24 is a diagram showing an APS byte time chart (part 4) when multiple failures occur. FIG. 25 is a diagram showing an example (part 5) of occurrence of multiple failures in the network. FIG. 26 is a diagram showing an APS byte time chart (part 5) when multiple failures occur. FIG. 27 is a diagram showing an example (6) of occurrence of multiple failures in the network. FIG. 28 is a diagram showing a time chart (No. 6) of the APS byte when multiple failures occur. FIG. 29 is a diagram showing an example (No. 7) of occurrence of multiple failures in the network. Figure 30 shows APS when multiple failures occur
It is a figure which shows the time chart (7) of a byte. FIG. 31 is a diagram showing a conventional APS byte. FIG. 32 is a diagram showing an APS byte of the present invention. FIG. 33 is a diagram showing an example of the basic operation of the switching protocol of the present invention. FIG. 34
FIG. 6 is a diagram showing an example of the basic operation of the switching protocol of the present invention with multiple failures.

[Explanation of symbols]

1 processing unit, 2 network table, 3 APS byte transmitting / receiving unit 4 monitor unit, 5 switching unit, 6 control unit, 7 backup transmission line terminating device 8 working transmission line terminating device, 9 backup transmission line, 10 working transmission line 11 fault comparison Judgment circuit, 12 Target station judgment circuit, 13
Signal determination circuit 14 State determination circuit, 15 APS byte processing unit 16 APS byte transmission setting unit, 17-20 AND gate circuit 20, OR gate circuit, 101-104 Transmission device 105-108 Working transmission line, 109-111 Spare transmission line, 112 Termination Device 113 Relay Device, 114 Demultiplexing Device, 115-1
18 transmission device 119-122 working transmission line, 123-126 backup transmission line 200-204 transmission device, 205-210 working transmission line 211-215 backup transmission line, 301-307 transmission device 308, 310 working transmission line 1, 309 working Transmission lines 2 and 311 Backup transmission lines

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-226729 (JP, A) JP-A-7-264156 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04J 3/00 H04L 1/22 H04L 12/00

Claims (20)

(57) [Claims] 1. A transmission frame having a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, wherein a transmission frame having overhead information is used. A self-relief network that performs digital transmission by means of: a transmission device, wherein the transmission device includes at least a memory unit that forms a network table that stores information regarding connection status of the network and fault information; and a fault in the working transmission line. and means for detecting said information, said generated in each of the transmission devices based on the overhead information of a transmission frame, the overhead information includes the number of active transmission line, a switching request of the transmission path And the number of the transmission device for notifying the transmission of the transmission line when the failure occurs in the working transmission line. Based on the overhead information of the over-time, the switching control information about the failure and exchanged between the transmission device constituting the network, the the switching control information about the failure of at least one of the transmission device is the switched network・
Based on the information stored in the table, the current
A self-relief network characterized by being configured to determine a transmission line for use and switch the transmission line. 2. The self-rescue type network comprises K (K is an integer of 3 or more) transmission devices, and (K-1) backup transmission lines connecting the transmission devices in a chain shape. The self-relief network according to claim 1, wherein the self-relief network has at least a plurality of working transmission lines that connect the transmission devices. 3. The self-rescue type network comprises K (K is an integer of 3 or more) transmission devices, K backup transmission lines connecting the transmission devices in a ring shape, and a plurality of connection devices connecting the transmission devices. 2. The self-relief network according to claim 1, which is a self-relief network having at least the working transmission line. 4. The self-relief network according to claim 1, wherein at least one of the transmission devices is connected to three or more working transmission lines. 5. A transmission frame having at least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, the transmission frame having overhead information. A self-relief network that performs digital transmission using at least the transmission device, wherein the transmission device includes at least a memory unit that forms a network table that stores information regarding connection status of the network and failure information, Is generated in each of the transmission devices based on information included in the overhead of the transmission frame, and the overhead information is at least a number of a current transmission line and a transmission device number for notifying a transmission line switching request. When the failure occurs in the working transmission path, the transmission frame is overwritten. Based on the information contained in the byte for automatic switching in the buffer, switching control information relating to the fault is exchanged between the transmission devices constituting the network, and at least one of the transmission devices is related to the exchanged fault.
A self-rescue type network configured to determine a working transmission path to be switched based on the switching control information and the information in the network table and switch the transmission path. 6. The network table includes connection information set up between transmission devices of a working transmission line, connection information set up between transmission devices of a standby transmission line, a transmission device number, a number assigned to a working transmission line, The self-relief network according to claim 1, wherein the self-relief network is for storing at least fault information of a transmission path in the network at a predetermined time. 7. The network table includes connection information set up between transmission devices of a working transmission line, connection information set up between transmission devices of a backup transmission line, a transmission device number, a number assigned to a working transmission line, 6. The self-relief network according to claim 5, wherein the self-relief network is for storing at least fault information of a transmission path in the network at a predetermined time. 8. At least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, wherein the transmission device is the network. Has a memory section that constitutes a network table that stores at least the connection status and failure information of the
At least the number of the transmission device that notifies the switching request
In a self-relief network that performs digital transmission using at least a transmission frame having overhead information configured to include , when at least one of the working transmission lines has a failure, at least the following steps are provided. Transmission line switching method for self-help network. (1) A step in which the first transmission device that has detected the failure notifies a predetermined second transmission device of a transmission path switching request using the overhead information . (2) A step in which the second transmission device, which has received the request for switching the transmission path, judges whether or not the backup transmission path corresponding to the switching request can be used, based on the information in the network table. (3) If it is possible to determine whether to use this backup transmission line,
The second transmission device makes a setting for switching to the backup transmission line and uses the overhead information.
And notifying the first transmission device of this switching setting. (4) The switching the first transmission device receiving the setting of performs channel switching setting of the effect of using pre-transmission path has been set the second transmission device is switched, and before
A step of notifying the second transmission device of the switching setting of the transmission path by using the overhead information . (5) A step in which the second transmission device, which has received the notification of the switching setting of the transmission path, performs a switching setting to use the backup transmission path for which the switching setting of the first transmission device is used. 9. The second transmission device is switched to the backup transmission line when the availability of the backup transmission line is not determined when at least one of the working transmission lines has failed. 9. The transmission path switching method for a self-relief type network according to claim 8, further comprising a step of not performing setting to effect. 10. At least a plurality of transmission devices, a plurality of backup transmission lines connecting the transmission devices, and a plurality of working transmission lines connecting the transmission devices, wherein the transmission device is the network. Has a memory unit that constitutes a network table that stores at least connection information and fault information of the
Notify the current transmission line number and transmission line switching request
In a self-relief network that performs digital transmission using at least a transmission frame having overhead information of a transmission frame configured to include at least the number of a transmission device, at least one of the working transmission lines has a fault. A method of switching a transmission path of a self-relief network, which has at least the following steps when it occurs. (1) A step in which the first transmission device that has detected the failure notifies overhead information to a predetermined second transmission device. (2) A step in which the second transmission device, which has received the overhead information, judges whether or not the backup transmission line corresponding to the received overhead information can be used, based on the information in the network table. (3) The second transmission device performs setting related to switching of the protection transmission line based on the determination as to whether or not to use the protection transmission line, and provides information related to the setting of the transmission line to the first transmission device. Steps to notify. (4) A step of rewriting the information stored in the network table with new information based on the determination as to whether or not the backup transmission path can be used. 11. The information stored in the network table includes connection information set between transmission devices of a working transmission line, connection information set between transmission devices of a standby transmission line, a transmission device number, and a working transmission line. 11. The self-relief according to claim 10, which includes at least path information of a backup transmission path used for signal rescue, a number assigned to a working transmission path, and current failure information of a transmission path in the network. Type network transmission line switching method. 12. The transmission path switching method for a self-relieving network according to claim 10, wherein the information stored in said network table is dynamically updated by a signal from said processing unit. . 13. A connection section for connecting a plurality of working transmission lines, a connecting section for a plurality of backup transmission paths, a monitor section for monitoring an abnormality of the working transmission path, and an adjacent transmission via the backup transmission path. A transmitter / receiver of information stored in an area for automatic switching in the overhead for exchanging fault information with a device, a network table for storing at least the connection status of the network and fault information, and this network Setting of transmission line switching and this transmission line switching based on the information stored in the table, the information of the transmission line monitoring result of the monitor unit, and the information stored in the area for automatic switching in the overhead of a processing unit that performs at least a notification to the adjacent transmission device settings, are stored in at least have an area for automatic switching in the overhead The information is configured so as to include at least the number of the working transmission line and the number of the transmission device that notifies the transmission path switching request. When the working transmission line has a failure, the overhead is recorded.
Based on the information stored in the area for automatic switching of
Configure the network with switching control information regarding failures
Between the transmission devices that are
Switching control information and information of the network table
The active transmission path to be switched is determined based on
A transmission device characterized by being configured so that the path can be switched . 14. The network table includes connection information set up between transmission devices on a working transmission line, connection information set up between transmission devices on a backup transmission line, a transmission device number, and a number assigned to a working transmission line. 14. The transmission device according to claim 13, wherein the transmission device stores at least the failure information of a transmission path in the network at a predetermined time. 15. The overhead information includes at least a number of a working transmission path having the highest degree of importance, a transmission apparatus number for notifying a transmission path switching request, and a switching response status of the transmission apparatus of this transmission apparatus. 14. The transmission device according to claim 13, wherein the transmission device is configured to include. 16. A transmission device used in a SONET or SDH network, comprising: a connection part with a plurality of working transmission lines; a connection part with a plurality of backup transmission lines; and a transmission device adjacent via a backup transmission line. Between SON
A transmission / reception unit that transmits / receives fault information using APS (Automatic Protection Switching) bytes defined by the overhead of an ET or SDH frame; and a network table that stores at least the connection status of the network and the fault information, When a failure occurs in the working transmission path, the working transmission path in which the failure has occurred is repaired by any one of the backup transmission paths based on the information stored in the network table and the information contained in the APS byte. The information contained in the APS byte is the number of the working transmission line.
And the number of the transmission device that notifies the transmission path switching request
And at least when the working transmission line fails, the overhead
Based on the information stored in the area for automatic switching of
Configuring the network switching control information about the serial failure
Between the transmission devices that are
Switching control information and information of the network table
The active transmission path to be switched is determined based on
A transmission device characterized by being configured so that the path can be switched . 17. The transmission device according to claim 16 , further comprising a detection unit that detects a fault in the working transmission line, wherein the processing unit is configured to detect a fault in the working transmission line. The information stored in the network table and the A
A transmission device, characterized in that, based on the information contained in the PS byte and the detection result of the detection means, it is determined whether or not the faulty working transmission line is to be relieved by any of the backup transmission lines. . 18. The transmission device according to claim 16 , wherein the failure includes signal deterioration. 19. The transmission device according to claim 16 , wherein the APS byte is priority information regarding the working transmission line that is being repaired by any of the backup transmission lines,
A transmission device comprising: priority information relating to the working channel in which a new failure has occurred, wherein the priority information is multiplexed into a K1 byte defined in the APS byte. 20. The transmission device according to claim 19 , wherein the first-stage processing unit is configured to, based on the priority information, select the backup transmission line that is relieving the currently relieved working transmission line. A transmission device, characterized in that it is used to judge whether or not to relieve the working transmission line in which the new failure has occurred.