JP5528187B2 - Digital cross-connect device and method - Google Patents

Description

  The present invention relates to a digital cross-connect device and method, and more particularly, to a digital cross-connect device and method for receiving a plurality of asynchronous signals, recombining the signals time-multiplexed with the asynchronous signals, and performing time-multiplexing and transmission. .

  As Internet traffic increases, communication capacity is increasing. In trunk transmission systems, 10 Gb / s or 40 Gb / s wavelength division multiplexing (WDM) transmission systems are used per wavelength. In addition, research and development is underway to realize transmission systems that exceed 100 Gb / s per wavelength.

  There is a digital cross-connect technology as a technology for flexibly handling a large capacity signal from such a transmission line. The digital cross-connect technology enables flexible handling of multiplexed signals by time-separating signals from a plurality of transmission lines, cross-connecting them, and time-multiplexing again.

  A specific example of the digital cross-connect device is an SDH (Synchronous Digital Hierarchy) cross-connect that enables dynamic path setting and optimal path selection (see, for example, Non-Patent Document 1). The configuration of the SDH cross connect is shown in FIG. The cross-connect device shown in FIG. 1 includes a frame conversion unit 30 connected to the reception unit 10, a synchronization switch unit 40 connected to each frame conversion unit 30, and a synchronization switch unit 40 between the reception unit 10 and the transmission unit. And a frame converter 50 connected between the transmitter 20 and the transmitter 20.

  As shown in the figure, the transmitted signal is O / E (optical-electrical) converted at the receiving unit 10 and then converted into an internal signal format by the frame converting unit 30 as necessary, and then the synchronous switch unit. 40 is switched. After switching, the signal is transmitted from the transmission unit 20 after the frame conversion unit 50 converts the internal signal format to the original signal format as necessary.

SDH 52Mb / s, 156Mb / s cross-connect equipment configuration technology, 1994 Autumn Meeting of IEICE.

  Recently, OTN signals defined in ITU-T recommendation G.709 are widely used as signals for large-capacity transmission. The OTN signal can be transmitted over a long distance with high reliability by adding a monitoring control function and an error correction code.

  In the SDH cross-connect device that has been widely used in the past, since each signal is synchronized, a synchronous switch is used, and a large-scale switch can be used. Problems arise when trying to cross-connect OTN signals using such a synchronous switch.

  Unlike SDH, each signal is asynchronous in OTN, so the synchronous switch cannot be used as it is. In the case of SDH, signals of the same type have the same bit rate, and even for different types of signals, the bit rate between signals has an integer multiple relationship. For example, the bit rate of STM-16 is 2.48832 Gb / s and STM-64 is 9.95328 Gb / s. There is a relationship of 9.95328 = 4 × 2.48832 between them. Therefore, a synchronous switch can be used. On the other hand, in OTN, even if the signals are of the same type, the nominal value of the bit rate is the same, but the actual bit rate may be based on an independent oscillator, and the bit rates are slightly different from each other. Furthermore, there is no simple bit rate relationship such as SDH between different types of signals.For example, the bit rate of OTU1 is 2.666 Gb / s and OTU2 is 10.709 Gb / s, and the relationship between them is 10.709 = 4 × It is 238/237 x 2.666, and there is no simple bit rate relationship like SDH. As described above, since the bit rate between each signal is asynchronous in OTN, it is not possible to cross-connect using the synchronous switch as it is.

  The present invention has been made in view of the above points, and an object thereof is to provide a digital cross-connect device and method capable of cross-connecting asynchronous signals such as OTN using a synchronous switch.

  FIG. 1 is a principle configuration diagram of the present invention.

An apparatus according to the present invention is a digital cross-connect device that receives a plurality of asynchronous signals, recombines signals that are time-multiplexed with the asynchronous signals, and re-multiplexes and transmits the signals .
A first frame conversion rate adjusting means 120 that maps the received signal to a digital frame as necessary and performs rate adjustment to synchronize all signals;
Synchronization switch means 130 for cross-connecting synchronized signals;
And a second frame conversion rate adjusting means 140 for returning the synchronized signal to the original signal.

More specifically, the device according to the present invention is a digital cross-connect device that receives a plurality of asynchronous signals, recombines the signals time-multiplexed with the asynchronous signals, re-multiplexes the signals, and transmits the signals.
A first frame conversion rate adjusting means for mapping the received signal to a digital frame as necessary and performing rate adjustment to synchronize all signals;
Synchronous switch means for cross-connecting synchronized signals;
A second frame conversion rate adjusting means for returning the synchronized signal to the original signal;
Which is connected upstream of the synchronous switch hands stage, lane distribution means for distributing the synchronization digital frame into a plurality of lanes,
Which is connected downstream of the synchronous switch hands stage, are cross-connected by the synchronization switch means, a lane combining means combines the signal distributed to plural lanes reproducing digital frame,
Have
The first frame conversion rate adjustment means includes:
In the case where the digital frame is a GFP (Generic Framing Procedure) frame, means for adjusting a rate by inserting a GFP idle frame is included.

In the above digital cross-connect device,
Said first frame conversion rate adjustment hand stage,
When the digital frame is an ODU (Optical-channel Data Unit) frame, the digital frame may be configured to include means for mapping and synchronizing the asynchronous signal to the payload area of the ODU frame.

  FIG. 2 is a diagram for explaining the principle of the present invention.

A method according to the present invention is a digital cross-connect method that receives a plurality of asynchronous signals, recombines signals that are time-multiplexed with the asynchronous signals, re-multiplexes the signals, and transmits them .
In an apparatus having first frame conversion rate adjusting means, synchronous switch means, and second frame conversion rate adjusting means,
The first frame conversion rate adjusting means maps the received signal to a digital frame as necessary (step 1), performs rate adjustment (step 2), and synchronizes all signals (step 3). A frame conversion rate adjustment step;
A synchronous switching step (step 4) in which the synchronous switch means cross-connects the synchronized signals;
The second frame conversion rate adjusting means performs a second frame conversion rate adjusting step (step 5) for returning the synchronized signal to the original signal.

More specifically, the method according to the present invention is a digital cross-connect method that receives a plurality of asynchronous signals, recombines the signals time-multiplexed with the asynchronous signals, re-multiplexes the signals, and transmits the signals.
The first frame conversion rate adjusting means, synchronous switch means comprises a second frame conversion rate adjusting means, lane distribution means is provided in front of the synchronous switch means, lane coupling means downstream of the synchronization switch means In the equipment provided,
A first frame conversion rate adjusting step for mapping the received signal to a digital frame and adjusting the rate as necessary to synchronize all signals;
A synchronous switching step in which the synchronous switch means cross-connects the synchronized signals;
A second frame conversion rate adjusting step in which the second frame conversion rate adjusting means returns the synchronized signal to the original signal;
And
The lane distribution means distributes the synchronization digital frame into a plurality of lanes,
The lane coupling means are cross-connected with the synchronous switch means couples the signal distributed to plural lanes, to play digital frame,
In the first frame conversion rate adjustment step,
If the digital frame is a GFP (Generic Framing Procedure) frame, the rate is adjusted by inserting a GFP idle frame.

In the above digital cross-connect method,
In the first frame conversion rate adjustment step,
Wherein when the digital frame is ODU (Optical-channel Data Unit) frame, an asynchronous signal may be configured to synchronize mapped to the payload area of the ODU frame.

  According to the present invention, a digital frame generated based on a cross-connect clock by mapping a received signal to a digital frame before and after the synchronous switch and providing a frame conversion rate adjusting means for adjusting a rate. Asynchronous signals are accommodated at the time, and the rate is adjusted at that time to synchronize the signals and enable cross-connection using a synchronous switch.

It is a principle block diagram of this invention. It is a figure for demonstrating the principle of this invention. It is a block diagram of the digital cross-connect apparatus in the 1st Embodiment of this invention. It is a figure which shows the operation | movement (single lane) of the frame conversion rate adjustment part in the 1st Embodiment of this invention. It is a figure which shows the operation | movement (multilane) (the 1) of the frame conversion rate adjustment part in the 2nd Embodiment of this invention. It is a figure which shows the operation | movement (multilane) (the 2) of the frame conversion rate adjustment part in the 2nd Embodiment of this invention. It is another example of composition of a cross connect device in a 2nd embodiment of the present invention. It is an example of the digital frame utilized with the frame conversion rate adjustment part in the 3rd Embodiment of this invention. It is an example of the flame | frame used for the frame conversion rate adjustment part in the 4th Embodiment of this invention. It is an example of the digital frame utilized with the frame conversion rate adjustment part in the 5th Embodiment of this invention. It is a block diagram of the conventional digital cross-connect apparatus (SDH cross-connect).

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 3 shows the configuration of the digital cross-connect device according to the first embodiment of the present invention.

  In the figure, shaded portions indicate clock domains.

  The digital cross-connect device according to the present embodiment includes a reception unit 110, a transmission unit 150, a synchronization switch unit 130, a frame conversion rate adjustment unit 120 connected between the reception unit 110 and the synchronization switch unit 130, and a synchronization switch unit 130. And a frame conversion rate adjustment unit 140 connected between the transmission unit 150 and the transmission unit 150.

  The asynchronous signal is received by the receiving unit 110, subjected to optical-electrical conversion, etc., and input to the frame conversion rate adjusting unit 120. The frame conversion rate adjustment unit 120 accommodates asynchronous signals in digital frames as necessary and performs rate adjustment to synchronize all signals. The synchronized signal is cross-connected by the synchronization switch unit 130 and then input to the frame conversion rate adjustment unit 140. The digital frame is removed and the rate is adjusted back to the original asynchronous signal. The transmitter 150 transmits the asynchronous signal after performing electro-optical conversion or the like.

  FIG. 4 shows the operation (single lane) of the frame conversion rate adjustment unit in the first embodiment of the present invention. Hereinafter, a more detailed operation will be described with reference to FIG.

  A large number of frame conversion rate adjustment units 120 are arranged before and after the synchronous switch unit 130, but only one of them is shown in FIG. The frame conversion rate adjustment unit 120 performs synchronization between signals by asynchronously mapping the reception signal from the reception unit 110 to a digital frame. The digital frame may have an overhead, and can be used for a signal monitor of the synchronous switch unit.

  The plurality of digital frame signals synchronized by the frame conversion rate adjustment unit 120 are cross-connected by the synchronization switch unit 130 and then input to the frame conversion rate adjustment unit 140. The frame conversion rate adjustment unit 140 performs the reverse process of the previous frame conversion rate adjustment unit 120. That is, the signal accommodated in the digital frame is demapped to extract the original signal, and is transmitted to the transmission unit 150 as a transmission signal.

  The synchronous switch unit 130 operates at a clock frequency larger than the maximum clock value of the asynchronous signal to be cross-connected. For example, when 1.2 Gb / s, 1.3 Gb / s, and 1.4 Gb / s signals are handled as asynchronous signals, the rate of each asynchronous signal is adjusted to 1.5 Gb / s synchronized signals, operating at 1.5 Gb / s Cross-connect with a synchronous switch that

  As described above, the frame conversion rate adjustment unit 120 in the previous stage of the synchronous switch unit 130 maps the received signal to a digital frame and performs rate adjustment, whereby the asynchronous switch signal 130 can be cross-connected. It becomes possible.

[Second Embodiment]
In this embodiment, an example in which input / output signals are converted into multilanes will be described.

  FIG. 5 shows the operation (multilane) of the frame conversion rate adjustment unit in the second embodiment of the present invention.

  The cross-connect device shown in the figure has a configuration in which a lane distribution unit 210 is provided downstream of the frame conversion rate adjustment unit 120 having the configuration shown in FIG.

  There is a case where the bit rate of the signal to be handled is increased, and a signal higher than the bit rate that can be handled by the synchronous switch needs to be cross-connected. In that case, a cross-connect can be realized by using multi-lane transmission in which a single signal is distributed and transmitted to a plurality of lanes.

In the present embodiment, a lane distribution unit 210 is provided after the frame conversion rate adjustment unit 120 to distribute synchronized digital frames to a plurality of lanes, and then the synchronization switch unit 130 cross connects the signals. In the subsequent stage of the synchronization switch unit 130, the signals distributed to the plurality of lanes are combined by the lane combining unit 220 to reproduce the digital frame, and then input to the frame conversion rate adjustment unit 140. After that, the process is the same as in the first embodiment.
By adopting such a configuration, for example, in the case of cross-connecting 9 Gb / s, 10 Gb / s, and 11 Gb / s asynchronous signals with the synchronous switch unit 130 having a speed of 3 Gb / s or less, Each asynchronous signal is synchronized to 12 Gb / s by the frame conversion rate adjustment unit 120, and then the signal synchronized by the lane distribution unit 210 is converted into 4 lanes to be a 3 Gb / sx 4 signal by the synchronization switch unit 130. It becomes possible to cross-connect. The lane combining unit 220 converts the 3 Gb / s × 4 signal back to a 12 Gb / s signal, and then the original signal (9 Gb / s or 10 Gb / s or 11 Gb / s) by the frame conversion rate adjustment unit 140. Play.

  Note that the number of lanes may be different when the bit rate of the signal to be handled is wider. For example, assuming an OTN signal and handling an asynchronous signal of 2.666 Gb / s (OTU1), 10.709 Gb / s (OTU2), 43.018 Gb / s (OTU3) with the synchronous switch unit 130 at a speed of 3 Gb / s or less The frame conversion rate adjustment unit 120 synchronizes the 2.666 Gb / s signal to the 2.750 Gb / s signal, synchronizes the 10.709 Gb / s signal to the 11.000 Gb / s signal, and converts the 43.018 Gb / s signal to the 44.000 Gb / s signal. After synchronization, the lane distributor 210 synchronizes 2.750 Gb / s to 2.750 Gb / sx 1, 11.000 Gb / s to 2.750 Gb / sx 4, and 44.000 Gb / s to 2.750 Gb / sx 16. The switch unit 130 can be cross-connected.

  As a method of lane distribution and lane combination, set the number of logical lanes according to the number of physical lanes, use dummy bytes as necessary when dividing the OTU frame into blocks, and distribute the divided blocks to the logical lanes There is a multi-lane transmission method with an arbitrary number of lanes, sometimes using dummy blocks as necessary.

  As shown in FIG. 6, a configuration in which the order of the frame conversion rate adjustment unit 120 and the lane distribution unit 210 and the order of the frame conversion adjustment unit 140 and the lane combination unit 220 are reversed is also possible.

  FIG. 7 shows another configuration example of the cross-connect device according to the second embodiment of the present invention. 3 to 6 do not include the wavelength multiplexing unit 340 and the wavelength demultiplexing unit 310 that multiplex and demultiplex wavelength multiplexed signals, and the time multiplexing unit 330 and the time demultiplexing unit 320 that multiplex and demultiplex time multiplexed signals. It may be included as shown in

  Various bit rates may be mixed for each signal. For example, an ODU3 signal of 40G per wavelength is input on the input side of the cross-connect device, and these are time-separated into a plurality of ODUs (Optical-channel Data Units) and cross-connected as necessary. May be multiplexed and output as a 100G ODU4 signal per wavelength.

  As described above, the input / output signals are multi-laneed and combined with the frame conversion rate adjustment unit 120, so that the signals to be cross-connected by the synchronization switch unit 130 can be made to have the same bit rate signal synchronized. Various types of signals can be cross-connected.

[Third Embodiment]
In the present embodiment, an example of a digital frame used in the frame conversion rate adjustment units 120 and 140 shown in the first and second embodiments will be described.

  FIG. 8 is an example of a digital frame used in the frame conversion rate adjustment unit according to the third embodiment of the present invention.

  Consider using the GFP frame defined in ITU-T recommendation G.7041 as shown in the figure. GFP (Generic Framing Procedure) is a technique for encapsulating a packet signal. Here, encapsulating a CBR (Constant Bit Rate) signal is considered. As shown in FIG. 8, a 2048-byte GFP frame is formed by adding Core Header (4 bytes) and Payload Header (4 bytes), which are overheads of GFP, to certain bytes (2040 bytes in the figure). The rate is adjusted by appropriately inserting a GFP idle frame into such an encapsulated signal. The rate can be synchronized with a desired cross-connect clock according to the insertion amount of the GPF idle frame. The lower part of FIG. 8 shows the flow of signals and the clocks (reception clocks, cross-connect clocks) based on the signals and processing.

  Note that the number of bytes when encapsulating with GFP may be different from the above example, or may not be a fixed length.

[Fourth Embodiment]
In the present embodiment, an example of a digital frame different from that in the third embodiment is shown.

  In this embodiment, an ODU frame is used as a digital frame.

  FIG. 9 is an example of a frame used for the frame conversion rate adjustment unit in the fourth embodiment of the present invention. In the present embodiment, it is assumed that an ODU frame defined by ITU-T recommendation G.709 is used as shown in FIG. The asynchronous signal is mapped to the payload area of the ODU frame for synchronization. As a mapping method, GMP (Generic Mapping Procedure) or AMP (Asynchronous Mapping Procedure) can be considered. The lower part of the figure shows the signal flow and the clocks (reception clock, cross-connect clock) that are the source of the signals and processing.

[Fifth Embodiment]
In the third embodiment and the fourth embodiment described above, an example in which a new frame structure is prepared by a frame conversion rate adjustment unit such as a GFP frame or an ODU frame has been shown. Asynchronous signals received by the reception unit 110 When has a frame structure, the frame structure can be used as it is.

  In the present embodiment, processing of the frame conversion rate adjustment units 120 and 140 different from those in the third and fourth embodiments will be described.

  In the present embodiment, for example, when the frame conversion rate adjustment unit 120 receives an ODU signal as an asynchronous signal, the ODU signal is used as it is without being stored in another digital frame, as shown in FIG. For example, rate adjustment can be performed by inserting an idle signal or the like between frames of the ODU signal. The rate is adjusted by adjusting the amount of idle signal insertion. Further, the frame conversion rate adjusting unit 140 at the subsequent stage of the synchronous switch unit 130 removes the inserted idle signal and reproduces the original signal.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

110 reception unit 120 first frame conversion rate adjustment unit, frame conversion adjustment unit 130 synchronization switch unit, synchronization switch unit 140 second frame conversion rate adjustment unit, frame conversion adjustment unit 150 transmission unit 210 lane distribution unit 220 lane combination unit 310 Wavelength separator 320 Time separator 330 Time multiplexer 340 Wavelength multiplexer

Claims (4)

A digital cross-connect device that receives a plurality of asynchronous signals, recombines signals that are time-multiplexed with the asynchronous signals, re-multiplexes the signals, and transmits the signals.
A first frame conversion rate adjusting means for mapping the received signal to a digital frame as necessary and performing rate adjustment to synchronize all signals;
Synchronous switch means for cross-connecting synchronized signals;
A second frame conversion rate adjusting means for returning the synchronized signal to the original signal;
Lane distribution means connected to the preceding stage of the synchronization switch means and distributing the synchronized digital frame to a plurality of lanes;
Lane coupling means connected to the subsequent stage of the synchronous switch means, cross-connected by the synchronous switch means, combining signals distributed to a plurality of lanes, and reproducing a digital frame;
I have a,
The first frame conversion rate adjustment means includes:
When the digital frame is a GFP (Generic Framing Procedure) frame, the digital cross-connect device includes means for adjusting a rate by inserting a GFP idle frame . The first frame conversion rate adjustment means includes:
Wherein when the digital frame is ODU (Optical-channel Data Unit) frame, a digital cross-connect device of claim 1 further comprising means for synchronizing mapped to the payload area of the ODU frame asynchronous signal. A digital cross-connect method that receives a plurality of asynchronous signals, rearranges the signals time-multiplexed to the asynchronous signals, re-multiplexes the signals, and transmits the signals.
The first frame conversion rate adjusting means, synchronous switch means, have a second frame conversion rate adjusting means, lane distribution means is provided in front of the synchronous switch means, lane coupling means downstream of the synchronization switch means In the equipment provided ,
A first frame conversion rate adjusting step for mapping the received signal to a digital frame and adjusting the rate as necessary to synchronize all signals;
A synchronous switching step in which the synchronous switch means cross-connects the synchronized signals;
A second frame conversion rate adjusting step in which the second frame conversion rate adjusting means returns the synchronized signal to the original signal;
The stomach line,
The lane distribution means distributes the synchronized digital frame to a plurality of lanes;
The lane combining unit is cross-connected by the synchronous switch unit, combines signals distributed to a plurality of lanes, and reproduces a digital frame.
In the first frame conversion rate adjustment step,
When the digital frame is a GFP (Generic Framing Procedure) frame, the rate is adjusted by inserting a GFP idle frame . In the first frame conversion rate adjustment step,
The digital cross-connect method according to claim 3, wherein when the digital frame is an ODU (Optical-channel Data Unit) frame, an asynchronous signal is mapped to the payload area of the ODU frame and synchronized.

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