JP3574549B2 - Add-drop multiplexing terminal equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission system forming a backbone communication network, and more particularly to a transmission system including a transmission device having a redundant configuration.
[0002]
[Prior art]
FIG. 6 shows a transmission system provided with a transmission device (multiplexing terminal device) having a conventional 1 + 1 redundant configuration, and FIG. 7 shows a transmission terminal station side of the transmission device (here, a 3: 1 multiplexer). The configuration is shown. In FIG. 6, only one channel on the low-speed interface LS side has been described for the sake of simplicity. FIG. 6 shows signal transmission only in the uplink direction (direction from the transmission device 2A to the transmission device 2B), but the same applies to the downlink direction (direction from the transmission device 2B to the transmission device 2A). In FIG. 6, 1A and 1B denote opposing devices on the transmitting and receiving side as service nodes, 2A and 2B denote the transmitting devices as 3: 1 multiplexing terminal devices, and W and P denote opposing devices 1A and 1B and transmitting devices. A working channel and a protection channel for connecting 2A and 2B, and SEL is a selector for each channel W and P. In FIG. 7, LS is the low-speed interface, and HS is the high-speed interface.
[0003]
Therefore, as shown in FIG. 6, by adopting a redundant configuration by multiplexing the transmission devices 2A and 2B, even when a failure occurs in the high-speed working channel W, the opposite device can be connected without disconnecting the line. 1A can be sent to the target opposing device 1B. Although FIG. 6 shows a 1 + 1 redundant configuration, the same applies to an N: 1 redundant configuration in which one channel is provided for N channels.
[0004]
By the way, with the shift from conventional telephone-based communication networks to computer-based multimedia communication networks, it is necessary to increase the volume of data that can be handled more than ever, and the demands for backbone communication for each service will differ. Is coming. For this reason, it is desired not only to have a simple redundant configuration as in the past, but also to use these redundant functions in an unprecedented and flexible manner.
[0005]
FIG. 8 shows a transmission system employing a conventional 1 + 1 redundancy switching method using X-traffic. 6, only one channel on the low-speed interface LS side is shown for simplicity of explanation. In the 1 + 1 redundancy switching method using the extra traffic, during normal operation, a signal from a remote device 1C different from the remote device 1A is transmitted to the remote device 1D using the protection channel P on the high-speed interface HS side. However, when a failure occurs in the high-speed working channel W, a signal on the working side (that is, a signal from the opposing device 1A to the opposing device 1C) is sent using the high-speed protection channel P, and is transmitted from the opposing device 1C. Extra traffic to the opposing device 1D is cut off. Thus, an economical signal transmission service can be provided by effectively utilizing the redundancy function. FIGS. 9 and 10 show the operation status of the transmission device 2A on the transmitting end station side during the normal operation and the occurrence of a failure as described above. Although FIG. 8 shows a 1 + 1 redundant configuration, the same applies to an N: 1 redundant configuration in which one channel is provided for N channels.
[0006]
[Problems to be solved by the invention]
Since the conventional transmission system is configured as described above, economical signal transmission can be realized by using a 1 + 1 redundant configuration for extra traffic, but the unit of the extra traffic is only a multiplexed signal unit. Therefore, there is a problem that it cannot be handled as extra traffic on a low-speed interface basis or on a transmission bus basis. It is thought that such demands will increase as multimedia becomes more advanced in the future. In addition, when the demand for the backbone communication is diversified for each service, it is assumed that the opposing device side, that is, the service node side, has various switching systems in units of transmission buses. For example, transmission buses that do not have any redundant configuration can be considered for services that prioritize economic efficiency, such as transmission buses that do not have any redundant configuration. For such diversification on the opposite device side, conventional extra traffic was used. There was a problem that the switching method alone could not cope. Therefore, there is a demand for a switching method that can flexibly cope with diversification of opposing devices on the service node side.
[0007]
The present invention solves the above-described problems, and can flexibly cope with the switching method on the opposite device side by adding a function of releasing the standby system to the transmission device for each low-speed interface or transmission bus. It is another object of the present invention to provide a transmission system capable of providing an economical signal transmission service without deteriorating reliability.
[0011]
The add / drop multiplexing terminal device according to the first aspect of the present invention is a drop / insert type multiplexing terminal device used for a unidirectional path switching ring system that is a ring switching system, wherein clockwise and counterclockwise rotation is performed. A high-speed interface unit composed of two types, a time switch unit connected to the clockwise and counterclockwise high-speed interfaces, and a low-speed interface unit. The low-speed interface unit receives a low-speed interface signal from the opposite device, In the case of a transmission path that separates the signal into transmission path units and distributes it to the time switch, and in the case of a transmission path that opens the standby system, the signal of the system 0 is transmitted only to the clockwise high-speed interface through the clockwise clock switch , and signal and a function of viewing distribution to counterclockwise high-speed interface through counterclockwise time switches, during normal operation, regardless of the time of failure The transmission path unit, the redundant system of the opposing device, a high speed side of the redundant system to fixedly connected, in which a function for fixedly open pre備系.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a transmission system when a standby system is released in units of low-speed interfaces. For the sake of simplicity, only one channel of the low-speed interface LS for releasing the standby system is shown. For other channels, the conventional redundant configuration shown in FIG. 6 or the extra traffic configuration shown in FIG. 8 may be used. In this system, during normal operation, a signal from an opposing device 1C different from the opposing device 1A is sent to the opposing device 1D using the protection channel P on the high-speed interface HS side. At this time, the redundant system with the opposing device at the transmitting / receiving end and the redundant system on the high-speed side are operated in a fixed state as shown in FIG. Therefore, even if a failure occurs in the high-speed working channel W, the working-side signal (that is, the signal from the opposing device 1A to the opposing device 1C) is transmitted using the high-speed protection channel P. Not at all. As described above, by using the redundant configuration in a fixed manner, signal transmission without a redundant system can be provided in units of low-speed interfaces.
[0014]
FIGS. 2 and 3 show the state of the multiplexing terminal device on the transmitting terminal side during normal operation and when a failure occurs. In these figures, the standby system is opened only for channel 2 and the conventional redundant system is used for the other two channels. When a failure occurs in the high-speed working channel, the signal LS # 2 (W) of the working-side channel 2 is turned off, and the signal LS # 2 (P) of the protection-side channel 2 can be transmitted as it is. By opening the standby system in units of such low-speed interfaces, it becomes possible to handle the traffic as extra traffic in units of low-speed interfaces.
[0015]
Next, another embodiment of the present invention will be described for a case in which preliminary release in units of transmission buses is performed using a drop-and-insert multiplexing terminal equipment (ADM apparatus). Before showing the preliminary release, the ADM apparatus will be described first. FIG. 11 schematically shows a general unidirectional bus switching ring system (UPSR). On the transmitting end station side, the transmission bus from the opposing device is routed using the time switch TSW, and then distributed to the clockwise channel CW and the counterclockwise channel CCW on the high-speed side. For example, when a failure occurs in the CCW channel, the receiving end station switches to a route where no failure has occurred (the channel CW side in the figure) on a bus basis.
[0016]
FIG. 12 shows a configuration on the transmitting terminal side of a multiplexing terminal device (ADM device) which is the transmission device of FIG. Here, the number of transmission buses per low-speed interface LS is shown as three. For the sake of simplicity, the low-speed interface LS is shown only for one channel (LS # 1), and the transmission bus connected by this ADM device is also omitted for simplicity. . After receiving the low-speed interface signal from the opposite device, the low-speed interface LS first separates the low-speed interface signal into transmission bus units. Thereafter, as shown in FIG. 12, each transmission bus is distributed to a time switch (hereinafter, referred to as TSW-0) and a time switch (hereinafter, referred to as TSW-1) which is redundant in the device. The signal from TSW-0 is distributed to a clockwise high-speed interface (hereinafter, HS-CW) and a counterclockwise high-speed interface (hereinafter, HS-CCW). In the event of a transmission path failure, a transmission bus signal is transmitted by performing switching on a transmission bus basis on the receiving end station side.
[0017]
On the other hand, FIG. 4 schematically shows a unidirectional bus switching ring system in a case where a standby system is released in units of transmission buses according to the present invention. Is transmitted to the clockwise channel CW by HS-CW using TSW-0. On the other hand, the transmission bus on the protection side from the opposite device is transmitted to the counterclockwise CCW using TSW-1 which is TSW-0 which is redundant in the device. The transmission bus with the standby system released does not have a redundant system in the high-speed ring on both the working side and the protection side from the opposing device, and therefore does not switch even if a transmission line failure or the like occurs.
[0018]
FIG. 5 shows the configuration of the transmission apparatus (ADM apparatus) shown in FIG. 4 on the transmission terminal station side. Here, as in FIG. 12, the number of transmission buses per low-speed interface LS is shown as 3. For the sake of simplicity, the low-speed interface LS is shown only for one channel LS # 1, and the transmission bus connected by this ADM apparatus is omitted for simplicity.
[0019]
After receiving the low-speed interface signal from the opposite device, the low-speed interface LS first separates the low-speed interface signal into transmission bus units. After that, the normal transmission bus is distributed to the TSW-0 and the TSW-1 which is redundant in the device, but the transmission bus on which the standby system is released is protected by the working-side transmission bus to the TSW-0. Side transmission bus to TSW-1 (LS # 1 middle transmission bus). In each of the TSW-0 and TSW-1, routes are distributed in transmission bus units. The transmission bus from each of these TSW-0 and TSW-1 is distributed to HS-CW and HS-CCW. For the transmission bus for opening the standby system, the transmission bus on the working side is transferred to HS-CW. The transmission bus on the protection side is sent to the HS-CCW (the transmission bus in the middle of LS # 1). By opening the standby system in units of the transmission bus, the transmission bus switching system on the service node side located outside the ring device (for important services, the instantaneous switching system in the transmission bus unit, , Etc., which have no redundant configuration at all).
[0020]
【The invention's effect】
As described above, according to the present invention, the working channel from the opposing device can be transmitted to any low-speed interface or transmission bus using the redundancy function between the opposing devices, the high-speed side redundant function, and the intra-device redundancy function. (A low-speed interface unit or a transmission bus unit) is connected to the high-speed working channel of the transmission device, and a protection channel from the opposite device is connected to the high-speed protection channel of the transmission device. By adding the function of opening the standby system to the transmission device, it is possible to flexibly cope with the switching method on the opposite device side, and to provide an effect of providing an economical signal transmission service without losing reliability.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a transmission system according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a connection during a normal operation of the transmission device in FIG. 1;
FIG. 3 is a block diagram illustrating connection when a failure occurs in the transmission device in FIG. 1;
FIG. 4 is a block diagram showing a ring switching system of a drop-and-insert type multiplexing terminal device in a transmission system according to another embodiment of the present invention.
FIG. 5 is a block diagram showing connection of the add / drop multiplexing terminal in FIG. 4;
FIG. 6 is a block diagram showing a conventional transmission system.
FIG. 7 is a block diagram showing connection of the transmission device in FIG. 6;
FIG. 8 is a block diagram showing another conventional transmission system.
FIG. 9 is a block diagram showing connections during normal operation of the transmission device in FIG. 8;
FIG. 10 is a block diagram illustrating connection when a failure occurs in the transmission device in FIG. 8;
FIG. 11 is a block diagram showing a ring switching method of a drop-and-insert type multiplexing terminal device in a conventional transmission system.
12 is a block diagram showing the connection of the add / drop multiplexing terminal equipment in FIG. 11;
[Explanation of symbols]
2A, 2B Transmission equipment HS, HS-CW, HS-CCW High-speed interface LS Low-speed interface

Claims (1)

A drop-and-insert type multiplexing terminal device used for a unidirectional path switching ring system that is a ring switching system,
A high-speed interface unit composed of two types, clockwise and counterclockwise ;
A time switch unit connected to the clockwise and counterclockwise high-speed interface;
Consists of a low-speed interface
Slow interface unit receives the low-speed interface signals from the opposing device, it separates the signal to the transmission path unit, the function of distributing the time switch, in the case of the transmission path for performing a backup system open, right-handed system 0 signal Has a function of distributing the signal of the system 1 only to the clockwise high-speed interface through the clockwise switch, and to the clockwise high-speed interface only through the clockwise switch .
During normal operation, regardless of the time of the failure, the transmission path unit, the redundant system of the opposing device, a high speed side of the redundant system to fixedly connected, with the ability to fixedly open pre備系<br A drop-and-insert type multiplexing terminal device characterized by the above-mentioned features .

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