JP3976693B2 - Non-instantaneous switching system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a path switching method for a digital transmission system and ITU-T G.264. The present invention relates to a path switching method for a transmission system having an interface compliant with the optical transport network defined in 709.
[0002]
[Prior art]
In non-instantaneous switching, the signal to be switched without interruption is transmitted after branching to a different path (active transmission line and backup transmission line) on the transmission side, and the signal received from the active transmission line and backup transmission By storing the signals received from the path in the active memory and the standby memory for an arbitrary time, matching the phase when reading from each memory, and switching the signal reading from the active system to the standby system by external control It is feasible.
[0003]
In conventional non-instantaneous switching, ITU-T G. Switching in the path unit such as “VC-3” or “VC-4” of the synchronous digital hierarchy defined in 707 is realized.
[0004]
In the non-instantaneous switching system on a path basis, the phase alignment of each of the demultiplexed working path and backup path is performed on the transmission side by ITU-T G. A specific multi-frame pattern (identifier) is overwritten and inserted in the J1 byte or H4 byte of the POH specified in 707, branch transmission is performed to the active system and the standby system, and the paths of the active system and the standby system are specified on the receiving side. Based on the phase difference recognized by the multiframe pattern (identifier) of the active system VC, the read timing of the standby system path from the standby system memory is made coincident with the read timing of the active system path from the active system memory. The phase of the path signal and the backup VC path signal can be matched.
[0005]
[Problems to be solved by the invention]
However, the above-described conventional non-instantaneous switching for each VC path has the following problems. ITU-T G. In the digital multiplex transmission system compliant with the synchronous digital hierarchy defined in 707, a VC path corresponding to a low speed line such as 50 Mbps or 150 Mbps is included in the payload of an STM16 frame or an STM64 frame having a high bit rate such as 2.4 Gbps or 10 Gbps. Multiple lines are multiplexed and transmitted.
[0006]
In the case where the conventional instantaneous switching without VC path unit is applied to such a digital multiplex transmission system conforming to the synchronous digital hierarchy, the switching control circuit on the transmission side and the reception side is provided for each VC path unit to be demultiplexed. Since they are configured independently, as shown in FIGS. 5 and 6, there is a problem in that the device configuration becomes complicated in the transmitter and receiver of the digital multiplex transmission system.
[0007]
A switching control circuit is also required according to the number of multiplexed VC paths that should be uninterrupted, which makes the device configuration complex and the mounting volume significant, and is suitable for recent large-capacity digital multiplex transmission systems. No (first challenge).
[0008]
In addition, ITU-T G.I. The various uses of POH and SOH specified by the 707 Synchronous Digital Hierarchy are determined in their specifications, and there are cases where it is required to transfer a multiplex transmission signal transparently without overwriting the overhead. is there. In the conventional technique, a part of overhead bytes in the original signal is overwritten in order to give an identifier for phase recognition on the transmission side. In other words, in the conventional non-instantaneous switching technology, ITU-TG All of the POH and SOH defined in 707 cannot be transferred transparently (second problem).
[0009]
The present invention has been made against such a background, and solves the first and second problems, and provides an uninterruptible switching function suitable for recent large-capacity digital multiplex transmission systems. Objective.
[0010]
[Means for Solving the Problems]
A first aspect of the present invention includes a transmission side subsystem that transmits an original signal to two paths different from the active path and a backup path, and a reception side subsystem that receives the original signal from the two paths. The subsystem includes means for branching and transmitting the phase adjustment identifier to the different path together with the original signal, and the receiving side subsystem includes the phase difference between the phase adjustment identifiers received from two different paths together with the same original signal. Is a non-instantaneous switching system including a phase difference absorption unit that measures the phase difference and absorbs the phase difference, and a switching unit that switches a signal in which the phase difference is absorbed between active and standby.
[0011]
Here, the present invention is characterized in that, in the transmitting side subsystem, before the original signal is branched into two different paths, a new control byte is added without changing the original signal. A signal format converting means for performing processing, and an identifier giving means for giving a specific pattern as the identifier to a part of the control bytes added by the signal format converting means, After the switching of the signal selection system by the switching means, there is provided a signal restoration means for restoring the signal format converted by the signal format conversion means to the original signal format. Thereby, since the original signal is not changed, the second problem described above can be solved.
[0012]
Furthermore, in order to solve the first problem described above, for example, the signal format conversion means converts the original signal to be switched without interruption to the ITU-TG. 709 comprises ODU conversion means for converting into an ODU signal format defined by an optical transport network, and the identifier assigning means assigns the specific pattern as an identifier for phase adjustment to a part of an overhead byte of the ODU signal. The phase difference absorption means includes a working identifier detection means for detecting an identifier represented by the specific pattern from an overhead byte in the ODU signal received from the working transmission line, and an ODU signal received from the backup transmission line. Standby identifier detecting means for detecting an identifier represented by the specific pattern from the overhead bytes, active memory means for temporarily storing the ODU signal received from the working transmission line, and temporarily storing the ODU signal received from the standby transmission line Spare memory means, working identifier detection means and spare identifier detection Detecting the phase difference from the difference in arrival time of the specific pattern in the ODU overhead detected in the stage, and adjusting the time accumulated in the active memory means and the spare memory means based on the phase difference, Memory control means for matching the read phases of the ODU signals from the active memory means and the spare memory means, and the switching means reads the ODU signal from the active memory means or the spare memory means, thereby Alternatively, there is provided means for performing selection system switching of the standby system, and the signal restoration means comprises means for restoring the ODU signal read by the switching means to the original signal format.
[0013]
As a result, by using a part of the overhead of the ODU signal for inserting a specific pattern for phase recognition, for example, by accommodating an STM frame in which a client signal is multiplexed with a plurality of VC paths in the payload portion of the ODU signal. When implementing non-instantaneous switching for all multiplexed lines, there is no need to install a plurality of switching circuits in units of VC paths independently, and a switching circuit in units of ODUs using STM-N frames as payloads. This can be achieved by installing only one. Thereby, the first problem can be solved.
[0014]
Further, the original signal is obtained by converting the STM-N frame into an ODU frame having a different signal format before the specific pattern insertion for phase recognition and converting the ODU signal format into the STM signal format at the subsequent stage of the switching unit. Signal transmission and switching control can be performed while maintaining the transparency of the STM-N frame without changing the overhead bytes of the STM-N frame. Thereby, said 2nd subject can be solved.
[0015]
At this time, the means for giving the specific pattern is ITU-T G. A means for using a RES byte described in the 709 optical transport network as a phase adjustment identifier as an insertion position of the specific pattern, or a means for assigning the specific pattern is ITU-T G.709. A means for using an EXP byte described in the 709 optical transport network as a phase adjustment identifier as an insertion position of the specific pattern, or a means for assigning the specific pattern is ITU-T G.709. It is desirable to provide means for using the MFAS byte described in the 709 optical transport network as the phase adjustment identifier and the insertion position of the specific pattern.
[0016]
Note that a RES (Reserved for future international standardization) byte is a byte for leaving room to deal with a case where a new standardization item is added in the future, and is an unused byte at present. Therefore, this can be used as an identifier for phase adjustment.
[0017]
EXP (Experimental) is a byte reserved for various tests, and is an unused byte when the test is not performed. Therefore, this can be used as an identifier for phase adjustment.
[0018]
An MFAS (Multi Frame Alignment Signal) byte is an overhead indicating a multi-frame phase, and its value ranges from 0 to 255, and one multi-frame can be composed of 256 frames. Therefore, this can be used as an identifier for phase adjustment.
[0019]
A second aspect of the present invention is a transmission-side subsystem including means for branching and transmitting a phase adjustment identifier to a different path together with an original signal. The feature of the present invention is that the original signal is divided into two Before branching to the path, the original signal is not changed and the signal format conversion means for adding a new control byte is added to the control byte added by the signal format conversion means. And identifier providing means for assigning a specific pattern as the identifier.
[0020]
The signal format conversion means converts the original signal to be switched without interruption to the ITU-T G. 709 comprises ODU conversion means for converting into an ODU signal format defined by an optical transport network, and the identifier assigning means assigns the specific pattern as an identifier for phase adjustment to a part of an overhead byte of the ODU signal. It is desirable to provide.
[0021]
At this time, the means for giving the specific pattern is ITU-T G. A means for using a RES byte described in the 709 optical transport network as a phase adjustment identifier as an insertion position of the specific pattern, or a means for assigning the specific pattern is ITU-T G.709. A means for using an EXP byte described in the 709 optical transport network as a phase adjustment identifier as an insertion position of the specific pattern, or a means for assigning the specific pattern is ITU-T G.709. It is desirable to provide means for using the MFAS byte described in the 709 optical transport network as the phase adjustment identifier and the insertion position of the specific pattern.
[0022]
According to a third aspect of the present invention, there is provided a phase difference absorbing means for measuring a phase difference between phase adjustment identifiers received from two different paths, that is, an active signal and a backup together with the same original signal, and absorbing the phase difference. A receiving-side subsystem including switching means for switching a signal in which a phase difference has been absorbed between active and standby, and a feature of the present invention is that, on the transmitting side, before the original signal is branched and sent to two different paths In addition, a process for newly adding a control byte is performed without changing the original signal, and a specific pattern is given as the identifier to a part of the control byte added by the signal format conversion, After the signal selection system is switched by the switching means, signal restoration means for restoring the signal format converted by the signal format conversion to the original signal format is provided.
[0023]
In the signal format conversion, the ITU-T G. 709 is converted into an ODU signal format defined by the optical transport network, and the specific pattern is given as a phase adjustment identifier to a part of the overhead bytes of the ODU signal. A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in the received ODU signal, and an identifier represented by the specific pattern from the overhead byte in the ODU signal received from the backup transmission path. Standby identifier detection means for detecting the ODU signal received from the working transmission line, working memory means for temporarily storing the ODU signal received from the working transmission line, spare memory means for temporarily storing the ODU signal received from the backup transmission path, the working identifier detection means, The specific parameter in the ODU overhead detected by the spare identifier detection means. Detecting the phase difference from the difference in arrival time of the memory and adjusting the time accumulated in the current memory means and the spare memory means based on the phase difference, thereby allowing the current memory means and the spare memory means to Memory control means for matching the read phase of the ODU signal, and the switching means reads the ODU signal from the working memory means or the spare memory means, thereby switching the working system or the spare system. The signal restoration means preferably comprises means for restoring the ODU signal read by the switching means to the original signal format.
[0024]
As a result, an uninterruptible switching system that realizes uninterruptible switching while preserving the original signal, and further avoids complication of the device configuration, and a transmitting side subsystem and a receiving side used therefor A subsystem can be realized.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of the uninterruptible switching system of this embodiment. FIG. 2 is an ODU structure diagram. FIG. 3 is a diagram for explaining the first embodiment. FIG. 4 is a diagram for explaining the second embodiment.
[0026]
In this embodiment, as shown in FIG. 1, a transmission side subsystem 10 that transmits an original signal to two paths A and B, which are different from the active and backup, and a reception side that receives the original signal from the two paths A and B The transmission side subsystem 10 includes a branching unit 3 for branching and transmitting the phase adjustment identifier to the different path together with the original signal, and the reception side subsystem 20 includes two different signals with the same original signal. A phase difference absorption unit that measures the phase difference of the phase adjustment identifiers received from paths A and B and absorbs the phase difference, and a switching unit 18 that switches the signal in which the phase difference is absorbed between active and standby. The transmission-side subsystem 10 changes the original signal before branching it to two different paths A and B. That's true An ODU conversion unit 1 that performs a process of newly adding a control byte, and an identifier adding unit 2 that adds a specific pattern as the identifier to a part of the control byte added by the ODU conversion unit 1 The receiving-side subsystem 20 is provided with an original signal restoration unit 19 that restores the signal format converted by the ODU conversion unit 1 to the original signal format after switching of the signal selection system by the switching unit 18. .
[0027]
Next, the operation of the uninterruptible switching system of this embodiment will be described together with its configuration. The ODU conversion unit 1 converts the original signal to be switched without interruption to the ITU-T G.D. It converts into the ODU signal format prescribed | regulated by 709 optical transport network, and the identifier provision part 2 provides the said specific pattern as an identifier for phase adjustment to a part of overhead byte of an ODU signal.
[0028]
The phase difference absorbing means detects an identifier represented by the specific pattern from the overhead bytes in the ODU signal received from the path A, and detects the identifier from the overhead bytes in the ODU signal received from the path B. An identifier detection unit 15 that detects an identifier represented by a specific pattern, a memory unit 16 that temporarily stores an ODU signal received from the path A, a memory unit 17 that temporarily stores an ODU signal received from the path B, and an identifier A phase difference is detected from the arrival time difference of the specific pattern in the ODU overhead detected by the detection unit 13 and the identifier detection unit 15, and the time accumulated in the memory unit 16 and the memory unit 17 is adjusted based on the phase difference. To match the read phases of the ODU signals from the memory unit 16 and the memory unit 17 The switching unit 18 reads out the ODU signal from the memory unit 16 or the memory unit 17 to perform selection switching between the active system and the standby system, and the original signal restoration unit 19 includes the switching unit 18. The ODU signal read out by is restored to the original signal format.
[0029]
The identifier assigning unit 2 is an ITU-T G. The RES byte described in the 709 optical transport network is used as the phase adjustment identifier and is used as the insertion position of the specific pattern. The EXP byte described in the 709 optical transport network is used as an identifier for phase adjustment as an insertion position of the specific pattern, or ITU-T G.709. The MFAS byte described in the 709 optical transport network is used as the phase adjustment identifier and the insertion position of the specific pattern.
[0030]
The ODU signal is the G. G.709 optical transport network. This is a new transmission signal format suitable for large-capacity transmission different from 707. FIG. 2 shows an ODU structure diagram. G. In 709, a 4 × 3808 byte OPU overhead is added to a 4 × 3808 byte client signal, and an ODU overhead of 3 × 14 bytes is further added. In FIG. 2, the abbreviations are PM: Path Monitoring, TCM: Tandem Connection Monitoring, SAPI: Source Access Point Identifier, DAPI: Destination Access Point Identifier, RES: Reserved for future international standardisation, ACT: Activation / deactivation control channel, FTFL: Fault Type & Fault Location reporting channel, EXP: Experimental, GCC: General Communication Channel, APS: Automatic Protection Switching coordination channel, PCC: Pretection Communication Control channel, TTI: Trail Trace Identifier, BIP8: Bit Interleaved Parity-level 8, BIE: Backward Error Indication, BDI: Backward Defect Indication, STAT: Status, PSI: Payload Structure Identifier, PT: Payload Type, MFAS: Multi Frame Alignment Signal. Further, before sending a signal to the transmission medium, an OTU overhead and FEC are added, and the OTU frame of 4 × 4080 bytes is transmitted.
[0031]
G. The payload of the ODU1 frame and ODU2 frame regulated by 709 is G.709. Since it has a capacity capable of transmitting all the bit rates of the STM16 frame and the STM64 frame defined by 707, the bit loss of the STM-N signal does not occur due to the conversion to the ODU signal format. The payload portion of the ODU signal format includes not only STM-N signals but also ATM cells and ITU-TG. A GFP frame defined by 7041 can also be transmitted. In the block configuration of FIG. However, if the client signal is saved, another signal conversion unit may be used as the signal format conversion unit.
[0032]
Further, claims 3, 4, 5, 5, 8, 9, and 10 are all G.P. This is a non-instantaneous switching system that performs phase adjustment using an overhead byte defined in 709. Claims 3 and 8 use the RES byte shown in FIG. 2 as a phase adjustment identifier. Claims 4 and 9 use the EXP byte shown in FIG. 2 as the phase adjustment identifier. Claims 5 and 10 use the MFAS byte shown in FIG. 2 as the phase adjustment identifier.
[0033]
As described above, in the uninterruptible switching system of this embodiment, by using a part of the overhead of the ODU signal for inserting a specific pattern for phase recognition, for example, an STM frame in which a client signal is multiplexed with a plurality of VC paths. Is implemented in the payload portion of the ODU signal, so that it is not necessary to install a plurality of switching circuits in units of VC paths independently when switching without interruption for all multiplexed lines, and the STM-N frame This can be realized by mounting only one switching circuit in units of ODUs with the payload as the payload. Thereby, the first problem can be solved.
[0034]
Further, before inserting the specific pattern for phase recognition, the STM-N frame is converted into an ODU frame having a different signal format, and converted from the ODU signal format to the STM signal format at the subsequent stage of the switching unit 18, thereby Without changing the overhead bytes of a certain STM-N frame, signal transmission and switching control can be performed while maintaining the transparency of the STM-N frame. Thereby, said 2nd subject can be solved.
[0035]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0036]
(First embodiment)
FIG. 3 shows a form in which a highly reliable network system having a non-instantaneous switching function is realized by applying the present invention to an optical ADM ring system. The optical ADM ring system converts a plurality of signals received from a plurality of client interfaces into a plurality of locations by connecting optical ADM node devices having a function of wavelength-converting and multiplexing and transmitting the signals to a single optical fiber. It is a system that realizes large-capacity communication in the optical layer.
[0037]
The optical ADM ring system includes a client interface (IF and illustration) unit 21 connected to a client device, a wavelength add / drop unit 22 for branching, inserting, and passing a signal from each client interface unit 21 into a multiplexed signal, Each optical signal routed by the add / drop unit 22 is wavelength-multiplexed and configured with a WDM interface unit 23 having a function of transmitting to other nodes.
[0038]
In FIG. 3, a four-node optical ADM ring system is configured by the optical ADM node devices 30, 40, 50, 60, and a clockwise path A is between the optical ADM node device 30 and the optical ADM node device 40. The signal path of the counterclockwise path B is set.
[0039]
By applying the uninterruptible switching units 24 and 28 having the uninterruptible switching function of the present embodiment to the client interface units 21 and 27 of the optical ADM node devices 30 and 40, the path A and the path B are as follows: It is possible to realize instantaneous switching without interruption.
[0040]
The client signal input from the client interface unit 21 of the optical ADM node device 30 is inserted with a phase recognition pattern by the uninterruptible switching unit 24 equipped with the transmission side subsystem 10 of the uninterruptible switching system of this embodiment. The transmitted ODU signal is branched and transmitted through the route A and the route B. These ODU signals are phase-adjusted by an uninterruptible switching unit 28 equipped with the receiving subsystem 20 of the uninterruptible switching system of the present embodiment of the optical ADM node device 40 through different paths, and from any path The ODU signal is read out, and the original signal is restored from the ODU signal and output from the client interface unit 27.
[0041]
Thereby, for example, in the optical ADM node device 40, after detecting the failure of the route A, the selection system for reading the ODU signal is switched from the route A to the route B within 1 bit, so that a transmission line failure occurs. It becomes possible to automatically rescue the client signal without interruption.
[0042]
(Second embodiment)
FIG. 4 shows a form in which a highly reliable network system having an uninterruptible switching function is realized by applying the uninterruptible switching system of this embodiment to an optical cross-connect (OXC) system. is there.
[0043]
The optical cross-connect system is a system that realizes a large-capacity mesh network in an optical layer between a plurality of bases by connecting a plurality of OXC nodes 81 to 89 to each other. Each OXC node 81-89 transmits a signal received from a plurality of interface units through another interface unit after setting a route. In FIG. 4, a nine-point mesh network is realized by the OXC nodes 81 to 89.
[0044]
Assume that routes A and B by optical paths are set from the OXC node 81 to the OXC node 89 in the network shown in FIG. Also in this case, as in the first embodiment, the transmission side subsystem 10 of this embodiment shown in FIG. 1 is connected to the IF unit 70 of the OXC node 81, and the reception side subsystem is connected to the IF unit 71 of the OXC node 89. By applying 20, it is possible to switch the optical path between routes A and B without instantaneous interruption.
[0045]
【The invention's effect】
As described above, according to the present invention, the client signal is transmitted to the ITU-T G. The ODU signal is converted into an ODU signal defined in 709, a specific phase recognition multiframe (identifier) is inserted into a part of the overhead byte of the ODU signal, and transmitted to two different paths. By detecting a specific multi-frame for phase recognition from the signal, detecting the difference in arrival time of signals transmitted through different paths, and controlling the memory to absorb the difference in arrival time, the original signal as described above Can be switched without interruption, and the complication of the apparatus configuration can be avoided.
[Brief description of the drawings]
FIG. 1 is a block diagram of an uninterruptible switching system according to an embodiment.
FIG. 2 is an ODU structure diagram.
FIG. 3 is a diagram for explaining the first embodiment;
FIG. 4 is a diagram for explaining a second embodiment;
FIG. 5 is a block diagram (transmission side) of a conventional non-instantaneous switching system.
FIG. 6 is a block diagram of the conventional uninterruptible switching system (receiving side).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ODU conversion part 2 Identifier assignment part 3 Branch part 4, 5 Signal transmission part 10 Transmission side subsystem 11, 12 Signal reception part 13, 15 Identifier detection part 14 Memory control part 16, 17 Memory part 18 Switching part 19 Original signal restoration 20 Receiving side subsystem 21, 27 Client interface unit 22, 26 Wavelength dropping / inserting unit 23, 25 WDM interface unit 24, 28 Uninterruptible switching unit 30, 40, 50, 60 Optical ADM node device 70, 71 Interface unit 81 ~ 89 OXC node

Claims (9)

A transmission-side subsystem that transmits the original signal to two paths different from the active and backup, and a reception-side subsystem that receives the original signal from the two paths, wherein the transmission-side subsystem performs phase adjustment together with the original signal Means for branching and transmitting identifiers for different paths, and the receiving subsystem measures the phase difference of the phase adjustment identifiers received from two different paths together with the same original signal and absorbs the phase difference A non-instantaneous uninterruptible switching system including a phase difference absorbing unit that performs switching and a switching unit that switches a signal in which the phase difference is absorbed between active and standby,
In the transmitting subsystem,
ITU-T with newly added overhead bytes for control without changing the original signal before branching the original signal to two different paths
G. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
Identifier adding means for giving a specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal added by the ODU conversion stage means,
The receiving-side subsystem includes signal restoration means for restoring the signal format converted by the signal format conversion means to the original signal format after the signal selection system is switched by the switching means,
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. Means for restoring the generated ODU signal to the original signal format ,
The identifier giving means is ITU-T. G. A non-instantaneous switching system comprising means for using a RES byte described in a 709 optical transport network as an insertion position of the specific pattern . A transmission-side subsystem that transmits the original signal to two paths different from the active and backup, and a reception-side subsystem that receives the original signal from the two paths, wherein the transmission-side subsystem performs phase adjustment together with the original signal Means for branching and transmitting identifiers for different paths, and the receiving subsystem measures the phase difference of the phase adjustment identifiers received from two different paths together with the same original signal and absorbs the phase difference A non-instantaneous uninterruptible switching system including a phase difference absorbing unit that performs switching and a switching unit that switches a signal in which the phase difference is absorbed between active and standby,
In the transmitting subsystem,
Before branching the original signal to two different paths, the ITU-T G.1 is newly added with an overhead byte for control without changing the original signal. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
Identifier adding means for giving a specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal added by the ODU conversion stage means,
The receiving-side subsystem includes signal restoration means for restoring the signal format converted by the signal format conversion means to the original signal format after the signal selection system is switched by the switching means,
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. Means for restoring the generated ODU signal to the original signal format ,
The identifier giving means is ITU-T. G. A means for using the EXP byte described in the 709 optical transport network as the insertion position of the specific pattern
Hitless switching system, characterized in that. A transmission-side subsystem that transmits the original signal to two paths different from the active and backup, and a reception-side subsystem that receives the original signal from the two paths, wherein the transmission-side subsystem performs phase adjustment together with the original signal Means for branching and transmitting identifiers for different paths, and the receiving subsystem measures the phase difference of the phase adjustment identifiers received from two different paths together with the same original signal and absorbs the phase difference A non-instantaneous uninterruptible switching system including a phase difference absorbing unit that performs switching and a switching unit that switches a signal in which the phase difference is absorbed between active and standby,
In the transmitting subsystem,
Before branching the original signal to two different paths, the ITU-T G.1 is newly added with an overhead byte for control without changing the original signal. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
Identifier adding means for giving a specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal added by the ODU conversion stage means,
The receiving-side subsystem includes signal restoration means for restoring the signal format converted by the signal format conversion means to the original signal format after the signal selection system is switched by the switching means,
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. Means for restoring the generated ODU signal to the original signal format ,
The identifier giving means is ITU-T. G. A means for using an MFAS byte described in a 709 optical transport network as an insertion position of the specific pattern;
Hitless switching system, characterized in that. A transmission-side subsystem including means for branching and transmitting an identifier for phase adjustment together with an original signal to a different path,
Before branching the original signal to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
An identifier providing means for giving the specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal converted by the ODU conversion means ,
The identifier giving means is ITU-T. G. 709 includes means for using the RES byte described in the optical transport network as the insertion position of the specific pattern
A transmitting subsystem. A transmission-side subsystem including means for branching and transmitting an identifier for phase adjustment together with an original signal to a different path,
Before branching the original signal to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
An identifier providing means for giving the specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal converted by the ODU conversion means ,
The identifier giving means is ITU-T. G. A means for using the EXP byte described in the 709 optical transport network as the insertion position of the specific pattern
A transmitting subsystem. A transmission-side subsystem including means for branching and transmitting an identifier for phase adjustment together with an original signal to a different path,
Before branching the original signal to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. 709 ODU conversion means for converting into an ODU signal format defined by the 709 optical transport network;
An identifier providing means for giving the specific pattern as an identifier for phase adjustment to a part of the overhead byte of the ODU signal converted by the ODU conversion means ,
The identifier giving means is ITU-T. G. A means for using an MFAS byte described in a 709 optical transport network as an insertion position of the specific pattern;
A transmitting subsystem. Phase difference absorption means for measuring the phase difference of the phase adjustment identifiers received from two different paths of the current and backup together with the same original signal and absorbing the phase difference; and the signal with the absorbed phase difference as the current A receiving-side subsystem including switching means for switching between backup and standby,
On the transmission side, before the original signal is branched and transmitted to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. ITU-T which is converted into an ODU signal format defined by the 709 optical transport network and is a part of the overhead byte of the converted ODU signal G. The RES byte described in the 709 optical transport network is given a specific pattern as the phase adjustment identifier ,
A signal restoration means for restoring the signal format converted to the ODU signal format to the original signal format after switching the signal selection system by the switching means;
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. A receiving subsystem comprising: means for restoring the converted ODU signal to the original signal format. Phase difference absorption means for measuring the phase difference of the phase adjustment identifiers received from two different paths of the current and backup together with the same original signal and absorbing the phase difference; and the signal with the absorbed phase difference as the current A receiving-side subsystem including switching means for switching between backup and standby,
On the transmission side, before the original signal is branched and transmitted to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. ITU-T which is converted into an ODU signal format defined by the 709 optical transport network and is a part of the overhead byte of the converted ODU signal G. A specific pattern is assigned to the EXP byte described in the 709 optical transport network as an identifier for the phase adjustment ,
A signal restoration means for restoring the signal format converted to the ODU signal format to the original signal format after switching the signal selection system by the switching means;
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. A receiving subsystem comprising: means for restoring the converted ODU signal to the original signal format. Phase difference absorption means for measuring the phase difference of the phase adjustment identifiers received from two different paths of the current and backup together with the same original signal and absorbing the phase difference; and the signal with the absorbed phase difference as the current A receiving-side subsystem including switching means for switching between backup and standby,
On the transmission side, before the original signal is branched and transmitted to two different paths, the original signal to be switched without interruption is not changed, and an overhead byte for control is added. ITU-T which is converted into an ODU signal format defined by the 709 optical transport network and is a part of the overhead byte of the converted ODU signal G. 709 specific pattern MFAS bytes described optical transport network as an identifier for the phase adjustment is applied,
A signal restoration means for restoring the signal format converted to the ODU signal format to the original signal format after switching the signal selection system by the switching means;
The phase difference absorbing means includes
A working identifier detecting means for detecting an identifier represented by the specific pattern from an overhead byte in an ODU signal received from a working transmission line;
Standby identifier detection means for detecting an identifier represented by the specific pattern from overhead bytes in the ODU signal received from the backup transmission path;
Working memory means for temporarily storing the ODU signal received from the working transmission line;
Spare memory means for temporarily storing the ODU signal received from the spare transmission path;
A phase difference is detected from a difference in arrival time of the specific pattern in the ODU overhead detected by the working identifier detecting means and the spare identifier detecting means, and is accumulated in the working memory means and the spare memory means based on the phase difference. Memory control means for adjusting the read phase of the ODU signal from the active memory means and the spare memory means by adjusting
The switching means comprises means for switching the active or standby system by reading an ODU signal from the working memory means or the spare memory means, and the signal restoring means is read by the switching means. A receiving subsystem comprising: means for restoring the converted ODU signal to the original signal format.

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