JPH09135228A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct changeover simultaneously for plural virtual containers by inverting a signal for phase difference detection to a path overhead added to a sent virtual container. SOLUTION: The operation system 1 is provided with a transmitter 2 and the transmitter 2 is provided with an equipment management section 3 and a main signal section 4. A phase difference detection signal is inserted into an overhead POH to be added to a sent virtual container VC by a synchronizing signal transmission module STM signal frame. Then the signal is sent in two paths, a receiver side absorbs a phase difference of an active and a standby system to select simultaneously the changeover of a virtual container VC so as to attain the changeover not in the unit of virtual container VC but in the unit of sections. Then a fault of a transmission line is detected by a bit error included in a path overhead POH of the virtual container VC to attain automatic changeover. Thus, the changeover form is revised easily by revising part or all of setting of the software.

Description

Detailed Description of the Invention

[0001]

This invention relates to the ITU by the International Telecommunications Union Telecommunication Standardization Sector (ITU-TS).
-Synchronous Digital Hierarchy, hereafter referred to as "SD"
"H") transmission system switching method.

[0002]

2. Description of the Related Art FIG. 10 shows a basic configuration of an SDH transmission system, and FIG. 11 shows an STM (synchronous transfer mode: Synchronouou).
s Transfer Mode) signal frame structure.

In Japan, the SDH transmission system has been introduced from the first year of 1989 in accordance with the new synchronous interface (NNI) standardized by the ITU-T recommendation. As shown in FIG. 10, this system includes a module A for transmitting and receiving an STM-N (synchronous transfer module N), a module B for setting a line for each VC-11 (virtual container 11), and a conventional transmission. It is constructed by the module C that performs conversion with the system. The section where the modules A face each other is called a section, and an intermediate repeater is used between the modules A when the distance is long. The opposing section of module B is called a path.

The STM signal frame adopted in the SDH transmission system has a frame length of 125 μs and 9 rows × 2.
STM-1 (Synchronous with 70-byte signal structure)
Transport Module Level 1) is the basic frame. S
The accurate transmission rate of TM-1 is 155.52 Mbit / s
However, for simplicity, it may be expressed as “156 Mbit / s”. In addition, in order to represent the transmission rate of information excluding overhead, it may be expressed as "150 Mbit / s". STM-1 is provided with a section overhead (SOH) of 9 rows x 9 bytes, and the remaining 9 rows x 2
61 bytes are used as a payload for information transmission. The N-multiplexed STM-1 is called STM-N.
In addition, STM-0 with 9 rows × 90 bytes and SOH of 9 rows × 3 bytes is also defined. In the payload, a virtual container VC-3, VC-4 or VC-4-Xc is transmitted. Each of these virtual containers is a path overhead (POH) of 9 rows x 1 byte, which is obtained by multiplexing VC-11 of 9 rows x 3 bytes.
It has a signal structure to which is added. For example, VC-3 has 9 rows x
It has a signal structure of 85 bytes and is 9 rows x 84 following POH.
VC-11 is multiplexed on the byte. VC-11, VC-
3 and STM-1 are 2 at 64 kbit / s conversion
It corresponds to 4 lines, 672 lines, and 2016 lines.

With respect to such an STM signal frame, the module A performs a section overhead (SOH) termination process. Since the module B connects the modules A and C with the STM-1, the termination processing of SOH and POH is performed.

12 and 13 are diagrams for explaining transmission path switching in section units by the module A, and FIG.
2 shows switching by a command, and FIG. 13 shows automatic switching by detection of a transmission line disconnection.

In general, the optical fiber forming the indoor transmission line which the module A faces is laid under the road or underground of the building, or is imaginarily wired by a utility pole or the like. For this reason,
When constructing roads and buildings, there are cases where the optical fiber must be cut. In addition, it is possible that the optical fiber is cut due to an unexpected transmission line failure. The higher the multiplicity of the signal propagating through the optical fiber, the greater the influence upon disconnection.
If the optical fiber through which the signal of 0 Mbit / s propagates is cut, about 8000 lines are disconnected when converted to a telephone. In order to deal with such a situation, the module A has a working transmission line and a protection transmission line, and is switched in units of sections. Therefore, the influence can be minimized by switching the transmission line before construction and cutting the target optical fiber to perform construction. In addition, even when a signal break due to an optical fiber break is detected, the transmission path is automatically switched.

When the transmission path is switched by the module A, the SO
By using the K1 and K2 bytes defined in advance in H, the device that recognizes the switching trigger can perform bidirectional switching while communicating with the opposite device. That is, in the case of the compulsory switching of the transmission path by the command, the device which has received the compulsory switching request inserts K1 and K2 bytes and transmits them to the opposite device. On the opposite device,
The K1 and K2 bytes are received, the transmission path is switched, and the completion is returned using the K1 and K2 bytes. Upon receiving the notification of switching completion, the device also executes the transmission path switching. Similarly, in the case of automatic transmission line switching due to detection of transmission line disconnection, the device that has detected the transmission line failure inserts K1 and K2 bytes and sends it to the opposite device, and then performs the transmission line switching in the same manner. To do. For the K1 and K2 bytes, the bit assignment is determined by the ITU-T recommendation so that the type of switching request, the requested transmission path, and the like can be recognized.

However, in the section switching by the module A, since the transmission path distance is different between the working and protection channels, a phase difference occurs between the two signals received on the receiving side, and when switching is performed, the STM frame is out of synchronization. . Therefore, ST
A momentary interruption will occur until the synchronization of M frames is restored. Switching without interruption is desired in important sections. This is called non-instantaneous interruption switching.

In order to perform non-instantaneous switching, (1) the phase difference resulting from the transmission path distance difference between the working system and the standby system is measured,
(2) The phase difference may be absorbed by the electric memory, and (3) the operation may be performed after confirming that the phase difference becomes zero.
In the case of the module A, a specific byte in the SOH is used for measuring the phase difference, and a phase difference detection circuit and a phase difference absorption memory are provided in the circuit for processing the SOH, so that the section can be switched without interruption. You can Such non-instantaneous interruption switching is hereinafter referred to as "switching mode a".

FIG. 14 is a diagram for explaining the principle of non-instantaneous switching in the switching mode a. In this case, the phase adjustment unit of the reception side module A stores the current system signal and the standby system signal in the memory, reads the same data so as to have the same phase, and switches this in the switching unit. If the circuit is operated so as to always match the phases of the two received signals, it is possible to perform non-instantaneous interruption switching without requiring a special switching sequence. That is, the apparent switching sequence is the same as the switching sequences shown in FIGS. 12 and 13, but no error or loss of synchronization occurs as a result of the switching. Also, section switching using the K1 and K2 bytes specified in the ITU-T recommendation can be used.

In the opposite section of the module A, a device for processing SOH such as a radio device may be installed in either the active system or the standby system. Such an example is shown in FIG. In this case, since it is not a single section, the specific byte of SOH is changed, and it is not possible to perform non-instantaneous switching. As a means for solving this problem, in Japanese Patent Laid-Open No. 5-110545 (Japanese Patent Application No. 3-203058), a signal for phase difference detection is inserted in a part of a POH byte on the transmitting side, and this byte is inserted on the receiving side. It has been proposed to use them for phase difference detection, phase difference absorption and switching. By doing this, S
Even if an apparatus for processing OH is installed, the POH is not changed, so that it is possible to switch without interruption. This non-instantaneous interruption switching is hereinafter referred to as "switching mode b".

FIG. 16 is a diagram for explaining the principle of non-instantaneous interruption switching in the switching mode b. This non-interruptible switching is the same as the switching mode a, except that POH is used instead of SOH.

However, in the module A, the switching mode b
In order to realize the above, a new switching sequence that replaces the switching sequence using K1 and K2 is defined, and VC-
It is necessary to perform switching in VC units of 3, 4, and 4-Xc.
In addition, in the switching mode b, when the working optical fiber is cut and construction is desired, the VC accommodated in this optical fiber is cut.
-3, 4, and 4-Xc must be specified one by one, and all must be individually switched to the standby system.

There has been proposed non-interruptible switching capable of coping with an unexpected transmission line failure. For example, Japanese Patent Application No. 7-18022
5 (unpublished at the time of filing of this application), it is shown that a parity byte included in SOH or POH is used to detect a transmission line failure as an error. That is, the parity byte is inspected, and if there is an error, non-interruptive switching is performed. In order to compensate for the time delay due to the parity calculation, a fixed delay is inserted before the switch for switching. This non-instantaneous interruption switching is hereinafter referred to as "switching mode c". In the switching mode c,
(1) The receiver always performs phase comparison, and the memory absorbs the phase difference. (2) When an unexpected transmission line failure occurs in the active system, the receiver disconnects the input, loses synchronization,
Detecting any of the bit errors, (3) Before the signal passes through the fixed delay unit and reaches the switching unit, the switching switch is operated to perform non-instantaneous switching.

FIG. 17 is a diagram for explaining the principle of non-instantaneous interruption switching in the switching mode c. Here, the case of using POH is shown. Similar to the case of the switching mode b, the same data is set to the same phase in the phase adjustment unit, the parity check is performed in the arithmetic unit, and switching is performed when there is an error in the parity. A fixed delay is introduced into the switched signal by the reading unit to compensate for the time delay due to the parity calculation.

According to the switching mode c, not only unexpected switching but also planned switching can be performed without interruption.
Therefore, the reliability of the transmission path can be improved as compared with the switching modes a and b.

The above switching modes a, b and c can be implemented according to the mode and purpose of the transmission line. All of these non-instantaneous interruption switching are for improving the reliability of the transmission line, and are similar in principle. These comparisons are shown in Table 1.
Shown in

[0019]

[Table 1]

[0020]

However, the configurations for implementing these switching modes are different from each other and must be realized as separate transmission devices. Therefore, if it is desired to change the form or purpose of the transmission line, the transmission device must be changed, which is very uneconomical. For example, when the route of the transmission path in which the switching mode a is introduced needs to be changed and the section of the wireless terminal station must be inserted, the transmission device must be changed to one that can implement the switching mode b. Further, in order to further improve the reliability of the transmission path in which the switching modes a and b are introduced, it is necessary to change the transmission device to the switching mode c.

It is an object of the present invention to solve the above problems and to provide a transmission device capable of changing the switching mode only by changing the software.

[0022]

A transmission device of the present invention is a transmission side device for transmitting a signal of a synchronous transfer module (STM-N) to two working and standby transmission lines, and a synchronous transfer from the two transmission lines. A receiver device for receiving the signal of the module, and the sender device is a virtual container (VC-3, VC-4 or VC) included in the signal of the synchronous transfer module.
-4-Xc) includes a signal inserting means for inserting a signal for phase difference detection into a part of the control byte (POH), and the receiving side device is included in the signals of the synchronous transfer module received from the two transmission paths. Phase difference absorption means for measuring and absorbing the phase difference between the signals of the same virtual container by the signal for phase difference detection, and switching means for switching the signal of the virtual container in which the phase difference has been absorbed between active and standby. A transmission device including a selection unit for selecting a virtual container to be switched,
When a plurality of virtual containers are selected by the selecting means, a switching control means for causing the plurality of virtual containers to be switched by the switching means at the same time is provided.

That is, on the transmitting side for generating the STM-N signal, the POH of any or all VC-3, VC-4 or VC-4-Xc signals included in the STM-N signal.
Insert a signal for phase difference detection into a part of the byte and
The MN signal is transmitted to the two transmission lines. On the receiving side that terminates the STM-N signal, the ST received from two transmission lines
Identical VC-3, VC-4 or VC included in M signal
-4-The phase difference between Xc signals is measured by a POH byte, the phase difference is absorbed, and the phase difference is absorbed by VC-
3, VC-4 or VC-4-Xc signals are switched to perform non-instantaneous interruption switching. At this time, the switching target VC-3, V
The C-4 or VC-4-Xc signal is arbitrarily selected and the switching is performed simultaneously.

VC-3, VC-4 or VC to be switched
If -4-Xc is a part, this switching corresponds to the switching mode b described above. If the switching target is all VC-3, VC-4 or VC-4-Xc included in the STM-N signal, this switching causes a section using K1 and K2 bytes specified in the ITU-T recommendation. The switching, that is, the switching mode a described above can be realized.

A means for activating the switching control means by detecting a transmission line failure due to a bit error contained in the signal of the virtual container, and a switching means operating until the signal of the virtual container containing the bit error reaches the switching means. And means for delaying the signal of the virtual container containing the bit error. Thereby, the switching mode c can be realized.

Control means for controlling the operation of each means is provided,
When there is no means for activating the switching control means for realizing the switching mode c, all or part of the software of the control means is replaced, or a part of the setting of the software is changed to oppose each other. It is desirable to change two switching modes, that is, a switching mode a in which a section for transmitting and receiving by the synchronous transfer module is used as a unit, that is, a switching mode a in which virtual containers are used as a unit, that is, a switching mode b. When there is a means for activating the switching control means, it is desirable to similarly change the three switching modes including the switching mode c.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a block diagram showing an embodiment of the present invention. A transmission device 2 is provided below the operation system 1, and the transmission device 2 is
A device management unit 3 and a main signal unit 4 are provided. The main signal section 4 includes conversion of an electric signal and an optical signal, multiplexing, SOP processing,
Transmission of STM-N signal to two working and protection transmission lines, reception of STM-N signal from two transmission lines, STM
-VC-3, VC-4 or VC-4 included in the N signal
-Insertion of a signal for detecting a phase difference into a part of POH of the Xc signal, measurement of a phase difference between the same VC signals included in STM-N signals received from two transmission lines by a signal for detecting a phase difference, and Absorption, switching of the VC signal of which the phase difference has been absorbed between active and standby, VC-3, VC-4 or VC-4-X
detection of a transmission line failure due to a bit error included in the c signal,
Hardware 9 that performs a remedy, a lamp lighting, and a notification to the device management unit 3 when a change in information related to communication such as a signal disconnection or signal deterioration is detected or a device failure is detected by a self-diagnosis function; This hardware 9 controls the switching of the VC signal, and when a plurality of VCs are selected, the changeover switch control unit 5 that executes the switching for the plurality of VCs at the same time, and the bit error included in the VC signal. When the transmission line failure is detected by the switch, the changeover switch control unit 6 that activates the changeover switch control unit 5, the absorption of the phase difference and the setting of the delay amount, and the V including the bit error are detected.
A memory control unit 7 that sets the delay of the VC signal so that the switch operates before the C signal reaches the switch.
And a sequence controller 8 for selecting a virtual container to be switched and controlling the switching sequence.

Like the general-purpose computer, the device management section 3 is equipped with dedicated software on the operation system 1, monitors the information detected by the main signal section 4, and notifies the operation system 1. In addition, according to a request from the operation system 1, use / non-use of the function in the main signal unit 4, state change, and other control are performed.

The main signal unit 4 is provided with all the functions required for the switching modes a, b, and c, and the device management unit 3 selects the necessary functions and operates them comprehensively in order to switch the purpose. . That is, depending on which of the switching modes a, b, and c is selected, all or part of the software in the device management unit 3 may be replaced, or some of the software settings may be changed.

In this embodiment, in the main signal section 4,
Similar to the switching mode b, POH is used to perform non-instantaneous switching in VC units. The difference from the switching mode b is that when there are a plurality of VCs to be switched, these switching switches can be moved simultaneously in an interlocking manner. Changeover switch control unit 5
Then, it is controlled whether these switches are operated independently or in synchronization. If the switches associated with all the VCs accommodated in the section are interlocked with each other to perform the switching, it can be seen as a normal section switching to a maintenance person who handles the device.

In the switching mode a, the sequence of K1 and K2 bytes is used, whereas when the switching mode b is realized, it is necessary to switch only the target VC in accordance with the dedicated sequence. These switching sequences are executed by the sequence control unit 8 according to its purpose.

The main signal section 4 is also provided with a changeover switch control section 6 and a memory control section 7 in order to realize the switching mode c. The switching conditions a and b and the switching mode c have different requirements for the memory. In the switching modes a and b, the memory required is only for absorbing the phase difference, but in the switching mode c, a memory for fixed delay is additionally required. In this embodiment, these are realized by one memory, and the memory control unit 7 changes the usage method according to the switching mode. In the case of the switching modes a and b, the entire memory is used as an area that can be changed according to the phase difference. In the case of the switching mode c, a part of the memory is assigned to the fixed delay amount and the rest is used as an area that can be changed according to the phase difference. For a signal, the sum of the fixed delay and the phase difference is the delay.

The change-over switch control section 6 has changeover modes a and b.
Do not use when. In the switching mode c, when a transmission line failure is detected, the changeover switch is operated via the changeover switch control unit 5. Depending on the setting of the changeover switch control unit 5, either the interlocking of switches or the independent operation can be dealt with, and both the switching mode c in section units and the switching mode c in VC units can be realized.

As described above, by changing all or part of the software installed in the device management unit 3 or changing the settings, three types of non-interruptible switching can be realized according to the switching mode and purpose of the transmission path. it can. Even if the configuration of the transmission line is to be changed or the reliability is to be further improved, the introduction of a new device is unnecessary, which can contribute to the construction of an economical transmission line network.

[0035]

EXAMPLES Specific examples of the present invention will be described with reference to FIGS. Here, a case will be described as an example where 1 + 1 redundancy switching is performed for a device that transmits STM-4 in which STM-1 including VC-4 is multiplexed. Any of switching modes a, b, and c is possible for non-instantaneous switching,
It is possible to realize the conventional switching involving a momentary interruption. In the case of the switching mode c, it is possible in principle to use a section unit or a VC unit, but here, an example of a VC unit will be described.

FIG. 2 shows a block configuration of a transmission device for transmitting an STM-4 signal. Opposing transmission devices are connected via two transmission lines, which are referred to as A route and B route. Each transmission device includes a low-speed processing unit LS that transmits and receives STM-1 signals, and a multiplexing unit MUX that multiplexes STM-1 signals into STM-4 signals and vice versa.
And two high-speed processing units HS for working and protection for transmitting and receiving STM-4 signals to and from the opposite transmission device. STM-1, 16 or 64 is used as the STM signal on the high speed side, STM-0 is used as the STM signal on the low speed side, and VC-3, VC-4-4c, VC are used as the VC signals.
The present invention can be similarly implemented by using 4-16c. Further, in the following description, the redundant switching of STM-1 1 + 1 redundancy on the low speed side is omitted, but the same function as on the high speed side can be realized. This transmission device performs bidirectional transmission in the up and down directions, but in the following description, the STM-4 transmission section and the reception section of the main signal section will be described separately.

FIG. 3 shows the structure of the transmitter. In the transmitter,
The low-speed photoelectric conversion circuits 11 to 14, the SOH / pointer processing circuit 15, the J1 byte insertion circuit 16, the sequence control unit 17, the multiplexing circuits 18 and 19, and the high-speed photoelectric conversion circuits 20 and 21 are provided. Low speed photoelectric conversion circuits 11-14
Converts the four received STM-4 optical signals into electrical signals. The SOH / pointer processing circuit 15 performs SOH termination processing and pointer processing, and the J1 byte insertion circuit 16 inserts a phase detection signal into the POH byte of VC-4. The newly generated STM-1 is branched into two, and multiplexed into STM-4 by the multiplexing circuits 18 and 19. This S
The TM-4 is converted into an optical signal by the high speed electro-optical conversion circuits 20 and 21 and sent out to two paths, a working path and a standby path.

FIG. 4 shows a multiframe structure of a signal for phase detection. In this embodiment, J1 byte of 64 multi-frame structure is used as 1 byte of POH required for comparing the phase difference. That is, the J1 byte insertion circuit 16 inserts the 64 multi-frame structure into the J1 byte. Due to the multi-frame structure, STM
There is no problem even if a phase difference of more than the frame length (128 μm) occurs, and it is possible to cope with a path length difference of 8 ms (about 1600 km).

Further, in the switching sequence required for the switching modes b and c, the same definition as K1 and K2 is made in a part of the J1 byte, and it is used as a byte instead of the K1 and K2 bytes. The sequence control unit 17 sets whether to perform the processing of K1 and K2 or the processing of J1 depending on the difference between the switching modes a, b, and c. When performing the switching without allowing any interruption of the switching modes a, b, and c and allowing the interruption,
It is not necessary to insert the J1 byte.

FIG. 5 shows the structure of the receiving section. In the receiver,
High-speed photoelectric conversion circuits 31, 32, demultiplexing circuits 33, 3
4, SOH / pointer processing circuits 35 and 36, sequence control unit 37, B3 error detection circuits 39 and 40, phase difference detection circuits 41 and 42, memory circuits 43 and 44, memory size setting circuit 45, memory control unit 46, switching A switch control unit 48, switches 49 to 52, and low speed electro-optical conversion circuits 53 to 56 are provided. B3 error detection circuits 39, 40,
The phase difference detection circuits 41 and 42, the memory circuits 43 and 44, and the memory size setting circuit 45 are provided for each STM-1, and a bypass circuit 47 is further provided.

The high-speed photoelectric conversion circuits 31 and 32 respectively receive the STM-4 optical signal and convert it into an electric signal. The demultiplexing circuits 33 and 34 demultiplex the 600 Mbit / s electric signal into two-path STM-1 signals, and the SOH / pointer processing circuits 35 and 36 perform SOH termination and pointer processing. The B3 error detection circuits 39 and 40 use the SOP
/ B of POH for the same VC-4 signal output from the pointer processing circuits 35 and 36 and passing through different paths.
The 3 bytes and the parity calculation result are compared to determine whether or not a bit error has occurred. The detection result of the bit error is notified to the changeover switch control unit 38. The changeover switch control unit 38 detects the bit error and the input disconnection detection output from the high-speed photoelectric conversion circuits 31 and 32, and S.
When a bit error is detected by ORing with the frame out-of-sync detected by the OH / pointer processing circuits 35 and 36, the target switch 4 is detected via the changeover switch controller 48.
Instruct the switch to 9, 50, 51 or 52. However,
The changeover switch control unit 48 does not operate in the switching modes a and b or in the case of allowing momentary interruption, and operates only in the switching mode c. The phase difference detection circuits 41 and 42 detect J1 for the VC-4 that has passed the B3 error detection circuits 39 and 40.
Detect the byte position. Memory size setting circuit 45
Calculates the memory size required to absorb the phase difference and instructs the memory circuits 43 and 44. The phase difference of the VC-4 that has passed through the phase difference detection circuits 41 and 42 is absorbed by the memory circuits 43 and 44, and remains in the same phase even if it goes through different paths.

FIGS. 6A and 6B are views for explaining the usage form of the memory, FIG. 6A is a view for explaining the total amount of the memory and the memory for the phase difference caused by the path difference, and FIG. FIG. 3C is a diagram illustrating a delay of one frame. The memory control unit 46 uses the switching mode a,
The internal use method of the memory circuits 43 and 44 is managed according to the difference between b and c. Generally, in the case of non-interruption switching, it is necessary to consider that the length will change in the long term due to the construction of the optical cable or the like. Since it may be contracted or expanded from the initial value, it is necessary to set some memory in advance to deal with expansion / contraction. Naturally, it is also necessary to absorb the difference in path length. Further, in the switching mode c, the bit error included in the frame is caused by the switches 49 to 5 depending on the parity calculated for each frame.
Since it is necessary to switch before reaching 2, the fixed delay of at least 2 frames is required. When this is realized by using a variable memory, it becomes as shown in FIG. The memory control unit 46 does not realize these by independent memories, but sets one memory according to the switching mode. FIG. 7 shows memory settings in the case of switching mode a or b, and FIG. 8 shows memory settings in the case of switching mode c. That is, in the case of the switching mode a or b, the usage mode is a combination of FIGS. 6A and 6B, and in the switching mode c, the usage mode is a combination of FIG. 6C.

In the switching mode in which the instantaneous interruption is allowed, VC-4 is connected to the B3 error detecting circuits 39 and 40, the phase difference detecting circuit 41,
42 and memory circuits 43, 44 need not be passed. In particular, the memory circuits 43 and 44 only unnecessarily increase the delay time of the device, and it is better not to pass the memory circuits 43 and 44. Therefore, a bypass circuit 47 is provided,
At least the memory circuits 43 and 44 are bypassed. B3
The error detection circuits 39 and 40 and the phase difference detection circuits 41 and 42
There is no problem with passing, and it is not always necessary to bypass. The setting of the bypass circuit 47 can be realized by providing a dedicated control circuit and giving an instruction from the device management unit. Also,
B3 error detection circuits 39, 40, phase difference detection circuit 41,
It is also possible to make the portion including 42 and the memory circuits 43 and 44 a hardware option package so that it becomes a bypass in the unmounted state. Memory circuit 4
The same applies when only 3, 44 are optional packages.

The change-over switch control section 48 has a changeover form a,
In the case of b, it is possible to switch all the VC-4s simultaneously or independently according to the instruction from the device management unit. In the case of the switching mode c, the VC-4 is independently switched according to the instruction from the changeover switch control unit 38. FIG. 5 shows four switches 49 to 52 for switching the VC-4. If VC-
In the case of supporting all of 3, VC-4-4c, and VC-4-16c, the switch may be configured in the unit of VC-3, and the interlocking VC unit may be changed by the changeover switch control unit 48.

The VC-4 signals that have passed through the switches 49 to 52 are output as STM-1 optical signals by the low speed electro-optical conversion circuits 53 to 56, respectively.

In the above description, the transmission device capable of supporting any of the four switching modes a, b, c and the switching mode which allows momentary interruption has been described. On the other hand, an example in which the existing module A is modified to support four switching modes including the case of allowing a momentary interruption will be described below.

FIG. 9 shows a receiving portion of a transmission device adapted to the four switching modes by modifying the existing module A. Originally,
Module A is the section terminator and cannot typically handle POH. Since the module A can already support the switching mode that allows the instantaneous interruption, in order to further support the switching modes a, b, and c, (1) J1, B
Being able to process POH such as 3 and (2) Being able to prepare a switch capable of switching in VC units,
(3) It is necessary to be able to mount a memory. Therefore,
High-speed photoelectric conversion circuits 31, 32, demultiplexing circuits 33, 3
4, SOH / pointer processing circuits 35, 36 In the transmission device of the existing module A provided with the switch 60 for switching in units of sections and the low-speed electro-optical conversion circuits 53 to 56,
B3 error detection circuits 39, 49, phase difference detection circuit 41,
42, memory circuits 43 and 44, and a memory size setting circuit 45 that processes POH (hereinafter referred to as “option 1”) and a switch 6 that can be switched in VC units.
1 (hereinafter referred to as option 2) can be added later. Module A does not perform POH treatment, but V
Since processing for accommodating C in the STM frame is performed, options 1 and 2 are added to the portion where the VC signal passes. As for the switch, the one for switching the section (switch 60) is provided in advance.
Since it cannot be switched to a unit, it is installed after option 1 as option 2. In this way, although the switches 60 and 61 have a two-stage configuration and are redundant, most of the existing modules A can be used, which is very effective.

A circuit for J1 insertion is required on the transmitting side, but since a transmission / reception package is adjacent or integrated in a normal transmission device, a J1 insertion circuit is added to option 1 and it is added. There is no problem if used on the sending side.

In this embodiment, by implementing the option 1, the switching mode a is possible. Furthermore, by implementing the option 2, switching modes b and c are possible. In the example shown in FIG. 5, the fixed delay for the switching mode c is realized by the memory, but in the example shown in FIG. 9, a fixed delay of 2 frames may be provided before the switch 61 of the option 2. Ideally, the embodiment described with reference to FIGS. 2 to 8 is preferable, but it is important that the embodiment is as simple as possible in consideration of the modification, and depending on the configuration of the module A to be modified, FIG. The embodiment described with reference to FIG.

[0050]

As described above, the transmission apparatus of the present invention can have the functions required for the switching modes a, b, and c, and the apparatus management unit performs the necessary functions for switching the purpose. By selecting and setting and operating them comprehensively, any of the switching modes a, b, and c can be realized. Moreover, the change of the switching form is to replace all or part of the software in the device management section,
Alternatively, it is only necessary to change a part of the software settings, and it is possible to simply change.

Also, by making it possible to add as an option, it is possible to provide the functions required for the switching modes a, b, and c while diverting many of the modules A that are already in operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a transmission device that transmits an STM-4 signal.

FIG. 3 is a diagram showing a configuration of a transmission unit.

FIG. 4 is a diagram showing a multi-frame configuration of a signal for phase detection.

FIG. 5 is a diagram showing a configuration example of a receiving unit.

FIG. 6 is a diagram illustrating a usage pattern of a memory.

FIG. 7 is a diagram illustrating memory settings in the case of switching mode a or b.

FIG. 8 is a diagram illustrating memory setting in the case of switching mode c.

FIG. 9 is a block configuration diagram showing a reception unit of a transmission device corresponding to four switching modes by modifying an existing module A.

FIG. 10 is a diagram showing a basic configuration of an SDH transmission system.

FIG. 11 is a diagram showing an STM signal frame structure.

FIG. 12 is a diagram illustrating switching of transmission lines in section units by module A, which is switched by a command.

FIG. 13 is a diagram for explaining transmission line switching in section units by the module A and automatic switching by detection of transmission line disconnection.

FIG. 14 is a diagram for explaining the principle of hitless switching according to switching mode a.

FIG. 15 is a diagram showing an example in which an apparatus for processing SOH is installed in either the active system or the standby system of the opposing section of module A.

FIG. 16 is a diagram for explaining the principle of hitless switching according to switching mode b.

FIG. 17 is a diagram for explaining the principle of non-instantaneous interruption switching in switching mode c.

[Explanation of symbols]

 1 Operation System 2 Transmission Device 3 Device Management Unit 4 Main Signal Unit 5, 6, 38, 48 Changeover Switch Control Unit 7, 46 Memory Control Unit 8, 37 Sequence Control Unit 9 Hardware 11-14 Low Speed Photoelectric Conversion Circuit 15, 35, 36 SOH / pointer processing circuit 16 J1 byte insertion circuit 17, 37 Sequence control unit 18, 19 Multiplexing circuit 20, 21 High-speed electro-optical conversion circuit 31, 32 High-speed photoelectric conversion circuit 33, 34 Demultiplexing circuit 39, 40 B3 error detection circuit 41, 42 phase difference detection circuit 43, 44 memory circuit 45 memory size setting circuit 49 to 52, 60, 61 switch 47 bypass circuit 53 to 56 low speed electro-optical conversion circuit LS low speed processing unit HS high speed processing unit MUX multiplexing Department

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiaki Sato 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A transmission side device for transmitting a signal of a synchronous transfer module to two transmission lines, a working transmission line and a backup transmission line, and a reception side device for receiving a signal of the synchronous transmission module from the two transmission lines. The side device includes a signal insertion unit that inserts a signal for phase difference detection into a part of the control byte of the virtual container included in the signal of the synchronous transfer module, and the reception side device synchronizes the signals received from the two transmission paths. Phase difference absorption means for measuring and absorbing the phase difference between the signals of the same virtual container included in the signal of the transfer module by the signal for phase difference detection, and the signal of the virtual container in which the phase difference is absorbed is In a transmission device including a switching unit that switches between standby and standby, a selecting unit that selects a virtual container to be switched and a case where a plurality of virtual containers are selected by this selecting unit. , The transmission apparatus characterized by comprising a switching control means for executing simultaneously switching for the plurality of virtual containers by the switching means. 2. The transmission device according to claim 1, wherein said selecting means includes means for selecting all virtual containers included in the signal of the synchronous transfer module. 3. A means for activating a switching control means by detecting a transmission line failure due to a bit error contained in a virtual container signal, and the virtual container signal containing the bit error reaching the switching means. 2. The transmission device according to claim 1, further comprising means for delaying the signal of the virtual container containing the bit error so that the switching means operates. 4. A control means for controlling the operations of the signal inserting means, the phase difference absorbing means, the selecting means and the switching control means, the control means facing each other to perform transmission / reception of the synchronous transfer module. 3. The transmission device according to claim 1, further comprising means for executing two switching modes of switching in units of virtual containers and switching in units of virtual containers by changing software. 5. A control means for controlling the operations of the signal inserting means, the phase difference absorbing means, the selecting means, the switching control means and the starting means, the control means facing each other and the synchronous transfer module. 4. The transmission according to claim 3, further comprising means for executing three switching modes by changing software, that is, switching in units of sections for transmitting and receiving data, switching in units of virtual containers, and switching in which a transmission path failure is detected. apparatus.