JP4695171B2 - Optical digital transmission apparatus, optical digital transmission / reception system, and optical digital transmission method - Google Patents

Description

  The present invention relates to an optical digital transmission apparatus, an optical digital transmission / reception system, and an optical digital transmission method for accommodating a client signal in a transmission frame and transmitting it to a transmission line, for example.

 In an optical transmission system, SDH (Synchronous Digital Hierarchy) is internationally standardized as a digital hierarchy for multiplexing existing service signals. In the United States, SONET (Synchronous 0ptica1 Network) having the same frame structure as SDH has become a US standard. As for the current optical transmission system, an optical transmission system conforming to the SDH / SONET specification has become the mainstream, and so far it has been introduced in large quantities all over the world. As a platform for transparently transmitting various clients such as ATM and Ethernet (registered trademark) as well as SDH / SONET, based on the wavelength multiplexing transmission (WDM) system that can cope with the explosive increase of Internet traffic in recent years. OTN (Optical Transport Network) has been standardized and is expected to become the mainstream of future optical transmission systems (see Non-Patent Document 1).

 Also, with the explosive spread of the Internet, the number of Ethernet (registered trademark) interfaces has increased rapidly, and in 2007, the number of Ethernet (registered trademark) interfaces shipped exceeded the SDH / SONET interface. As Giga-class Ethernet (registered trademark) signals, a 1.25 Gbit / s 1 Gigabit Ethernet (1 GbE) signal and a 10.3125 Gbit / s 10 Gigabit Ethernet (10 GbE) LANPHY signal are standardized. In the future, 10GbE is expected to become the mainstream as a client signal for communication carriers. Furthermore, there is an increasing demand for connecting LAN environments scattered in remote locations as they are with LAY-PHY. Also, 40 / 100GbE standardization work has started as IEEE 802.3ba, and standardization is scheduled to be completed in 2010.

  The OTN client signal is premised on a SONET / SDH signal. The client signal bit rate of OTN is defined as 2.48832 Gbit / s (STM-16), 9.95328 Gbit / s (STM-64), 39.8112 Gbit / s (STM-256), and includes 1 GbE signal and 10 GbE signal. The signal and the bit rate of 40 GbE which is expected to be standardized in the future are different. As a method for accommodating a 10 GbE-LANPHY signal having a bit rate different from the currently standardized OTN client signal bit rate in a transparent and efficient manner, OTN using over-clocking is widely used. ing. Overclocking means that only the bit rate is increased at a ratio of 10.3125 / 9.995328, so that a 10.3125 Gbit / s 10GbE-LANPHY signal can be used as a client signal without changing the OTN frame configuration or functions. Is stored in the payload of the OTN as it is.

FIG. 6 is a system configuration example of the prior art. FIG. 6 shows an example in which STM-64 and 10 GbE-LANPHY signals are directly accommodated in the payload area of the OTU frame and transmitted by wavelength multiplexing (WDM). For example, when accommodating a 10 GbE-LANPHY signal, the bit rate is increased and accommodated directly in an OTU frame of 10.3125 × 255/237 = 11.0957 Gbit / s. The prior art as shown in FIG. 6 is widely used because OTN is based on WDM and a large capacity system can be realized by WDM even if the bit rate for each wavelength is different. Further, when accommodating a 10 GbE-LANPHY signal, additional signal processing is unnecessary, and efficient accommodation is possible at a low price, so that it is also documented in ITU-T (see Non-Patent Document 2). ).
ITU-T G.709 “Interfaces for the Optical Transport Network (OTN)”, [online], [searched on September 18, 2008], Internet <URL: http://www.itu.int/rec/dologin_pub .asp? lang = e & id = T-REC-G.709-200303-I !! PDF-E &type-items> ITU-T G.sup43 “Interfaces of IEEE 10G Base-R in Optical Transport Network (OTN)”, [online], [searched on September 18, 2008], Internet <URL: http: //www.itu. int / rec / T-REC-G.Sup43-200802-P / en>

  However, 40GbE, which is scheduled for completion in 2010, may be accommodated by overclocking 40G class OTU3 frames as in the case of 10GbE, but the problem is that optical components corresponding to the overclocking are required. There is.

  The present invention has been made in view of such circumstances, and is to provide a technique for accommodating a 40 GbE client signal in an OTU3 frame using an existing optical component.

  In order to solve the above problems, an optical digital transmission device according to an aspect of the present invention is an optical digital transmission device that accommodates a client signal in a transmission frame and transmits the transmission signal to a transmission line, and the client signal encoding rule is set. A code conversion unit for converting into another coding rule, a first signal speed adjustment unit for adjusting the signal speed of the client signal after conversion into another coding rule by inserting a fixed staff for speed adjustment, and the like And a second signal speed adjustment unit that adjusts the signal speed of the client signal after conversion into the coding rule of (2) by inserting positive stuff and negative stuff for speed adjustment.

  In the signal analysis apparatus, the transmission frame is ITU-T G.264. It may be an OTU3 frame with a transmission rate of 43.018 Gbit / s ± 20 ppm according to the definition of 709.

  In the above signal analysis apparatus, the client signal may be 41.25 Gbit / s ± 100 ppm of 40 GbE, and the other coding rule may be 1024B / 1027B.

  In the signal analysis apparatus, the client signal may be 41.25 Gbit / s ± 100 ppm of 40 GbE, and the other encoding rule may be 512B / 513B or 1024B / 1026B.

  In the signal analysis apparatus, the first signal speed adjustment unit may insert 12 bytes of fixed stuff, and the second signal speed adjustment unit may insert 3 bytes of positive stuff and 2 bytes of negative stuff. .

  In the signal analysis device, the first signal speed adjustment unit may insert 11 bytes of fixed stuff, and the second signal speed adjustment unit may insert 4 bytes of positive stuff and 1 byte of negative stuff. .

  In the signal analysis device, the first signal speed adjustment unit may insert 27 bytes of fixed stuff, and the second signal speed adjustment unit may insert 3 bytes of positive stuff and 2 bytes of negative stuff. .

  In the signal analysis device, the first signal speed adjustment unit may insert a fixed stuff of 26 bytes, and the second signal speed adjustment unit may insert a 4-byte positive stuff and a 1-byte negative stuff. .

  In order to solve the above problem, an optical digital transmission / reception system according to another aspect of the present invention includes an optical digital transmission apparatus and an optical digital transmission / reception system including the optical digital transmission apparatus that mutually transmit and receive client signals accommodated in a transmission frame. The optical digital transmission device includes a code conversion unit that converts a coding rule of a client signal into another coding rule, and a signal speed of the client signal after conversion into another coding rule is fixed for speed adjustment. A first signal speed adjusting unit that adjusts by inserting stuff, and a second signal that adjusts the signal speed of the client signal after conversion into another coding rule by inserting positive stuff and negative stuff for speed adjustment And an optical digital receiver that restores the client signal from the transmission frame. .

  In order to solve the above problem, an optical digital transmission method according to another aspect of the present invention is an optical digital transmission method in which a client signal is accommodated in a transmission frame and transmitted to a transmission line, and the client signal is encoded. A code conversion step for converting the law into another coding rule, and a first signal for adjusting the signal speed of the client signal converted into the other coding law by the code conversion step by inserting a fixed stuff for speed adjustment And a second signal speed adjustment step for adjusting the signal speed of the client signal converted into another coding rule by the code conversion step by inserting positive stuff and negative stuff for speed adjustment. It is characterized by.

  According to the present invention, a 40 GbE client signal can be accommodated in an OTU3 frame using existing optical components without newly preparing expensive optical components.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration example of an optical digital transmission / reception system 1 to which an optical digital transmission device 10 according to an embodiment of the present invention is applied. The optical digital transmission / reception system performs wavelength division multiplexing transmission by mapping a 40 GbE client signal (hereinafter referred to as “40 GbE client signal”) to an OTU3 frame defined by OTN. In addition, G. The bandwidth of the payload portion (hereinafter referred to as “OPU3 payload”) in the payload OPU3 of the OTU3 frame defined in 709 is 40.15 Gbit / s ± 20 ppm. Further, the interface specification for 40 GbE client signals is currently under discussion in IEEE 802.3ba, but is expected to be 41.25 Gbit / s ± 100 ppm. Accordingly, since the 40 GbE client signal has a wider band than the OPU3 payload, it cannot be accommodated in the OTU3 frame as it is.

  As shown in FIG. 1, the optical digital transmission / reception system includes an optical digital transmission device 10 and an optical digital reception device 20. The optical digital transmitter 10 includes a code conversion unit 11, an FS (Fixed Stuff) rate adjustment unit 12 (corresponding to a first signal speed adjustment unit of the present invention), a justification processing unit 13 (second signal speed of the present invention). Equivalent to an adjustment unit) and a transmission unit 14. The optical digital receiver 20 includes a receiving unit 23, a restoration processing unit 22, and a code conversion unit 21.

  The code conversion unit 11 of the optical digital transmission device 10 converts a coding rule (also referred to as a code conversion rule) of a 40 GbE client signal into another coding rule. More specifically, the code conversion unit 11 first terminates 64B / 66B encoding for a 40 GbE client signal that has been 64B / 66B encoded, and converts it to a MAC rate of 40.0 Gbit / s ± 100 ppm. Subsequently, the code conversion unit 11 performs transcoding processing for recoding the 64B / 66B OH unit and performing code conversion. For example, by performing 1024B / 1027B transcoding, a 40 GbE client signal is converted to 40.00 × 1027/1024 = Convert to a rate of 40.12 Gbit / s ± 100 ppm.

  The FS rate adjustment unit 12 adjusts the signal speed of the 40 GbE client signal after conversion into another coding rule by inserting a fixed stuff (FS) for speed adjustment. Since the 40 GbE client signal transcoded by the code conversion unit 11 has a narrower band than the OPU3 payload, it can be accommodated in the OPU3 payload itself. However, if it is simply accommodated, a part of the band of the OPU3 payload is excessive. End up. The FS rate adjustment unit 12 inserts fixed stuff into the remaining area of the OPU3 payload, and the bit rate at which the band of the 40 GbE client signal converted into another coding rule by the code conversion unit 11 substantially matches the band of the OPU3 payload. To rise.

  The justification processing unit 13 sets the signal speed of the 40 GbE client signal after conversion to another encoding rule to positive stuff (PJO (positive justification opportunity) bytes specified in OPU3) and negative stuff (specified in OPU3). NJO (negative justification opportunity) bytes). The band of the 40 GbE client signal into which the fixed stuff is inserted by the FS rate adjusting unit 12 rises to the vicinity of the band of the OPU3 payload, but the clock accuracy is ± because the fixed stuff synchronized with the 40 GbE client signal is inserted. This is because 100 ppm remains unchanged and is larger than the clock accuracy ± 20 ppm defined by OTN, and cannot be accommodated as it is due to the requirement of clock accuracy. That is, the justification processing unit 13 increases the number of PJO bytes and NJO bytes, relaxes the request due to clock accuracy, and can accommodate the 40 GbE client signal in the OPU3 payload. The positive stuff (PJO byte) is a speed adjustment stuff that is inserted when the bit rate of the 40 GbE client signal after conversion into another encoding rule is smaller than the bandwidth that can be accommodated in the OPU3 payload. The negative stuff (NJO byte) is a speed adjustment stuff that is inserted when the bit rate of the 40 GbE client signal after conversion to another encoding rule is larger than the bandwidth that can be accommodated in the OPU3 payload.

The relative clock accuracy to be supported is ± 120 ppm, which includes the clock accuracy ± 20 ppm of the OTN that is the accommodating side and the clock accuracy ± 100 ppm of the client signal side that is the accommodating side. As a result, relative clock accuracy of up to about 65 ppm (1 / (3808 × 4) ≈65 × 10 ⁻⁶ ppm) per byte with respect to the capacity of the OPU3 payload (3808 × 4 bytes) can be absorbed. If 2 bytes are defined for each PJO byte and 4 bytes are prepared in total, it is possible to accommodate the relative clock accuracy of ± 130 ppm.

  In addition, when the FS rate adjustment unit 12 uses the fixed stuff of 1 byte unit to adjust the rate, the bit rate is adjusted in 65 ppm steps, so that the bit rate is adjusted to exactly the capacity of the OPU3 payload. Therefore, it is considered necessary to prepare about 5 bytes including the PJO byte and the NJO byte.

  The transmission unit 14 accommodates the speed-adjusted 40 GbE client signal in the OPU3 payload, wavelength-multiplexes it with other 40 GbE client signals, and transmits them to the transmission path.

  The receiving unit 23 of the optical digital receiver 20 receives an OPU3 frame containing a 40 GbE client signal from the optical digital transmitter 10. The restoration processing unit 22 executes the reverse process of the justification processing unit 13 of the optical digital transmission device 10. Specifically, the restoration processing unit 22 refers to the PJO byte and NJO byte of the OPU3 frame, confirms the presence / absence of justification processing on the transmission side, and performs justification processing (indicated by the PJO byte and NJO byte ( Justification processing for returning to the original signal speed of the 40 GbE client signal is performed. Note that the number of PJO bytes and NJO bytes specified in the normal OPU3 frame is 1 byte each, but when accommodating 40GbE client signals, there are more than 4 bytes of NJO and PJO. And the definition related to the NJO byte needs to be expanded in advance. The code conversion unit 21 decodes the 1024B / 1027B transcoding process after JC processing, and further restores the original 40 GbE client signal by performing 64B / 66B encoding processing.

  2 to 5 are diagrams illustrating examples of accommodation (mapping) of 40 GbE client signals to OPU3 frames. A portion surrounded by a broken line in the OPU3 frame shown in FIGS. 2 to 5 is an OPU3 overhead, and a portion surrounded by an alternate long and short dash line is an OPU3 payload.

  FIG. 2 is a first example in the case of accommodating a 1024B / 1027B transcoded 40 GbE client signal. The accommodation example of FIG. 2 accommodates (inserts) 12-byte fixed stuff (FS in FIG. 2) in the OPU3 payload for a 1024B / 1027B transcoded 40 GbE client signal (denoted as D in FIG. 2). A 3-byte PJO byte (denoted as PJO1, PJO2, and PJO3 in FIG. 2) was inserted (defined) in the payload, and a 2-byte NJO byte (denoted as NJO1 and NJO2 in FIG. 2) was inserted (defined) in the OPU3 overhead. It is an example. In the accommodating example of FIG. 2, when the clock accuracy on the OTN system side is ± 20 ppm, the accommodable bandwidth is 40.1549 Gbit / s (when the OTN system side clock is −20 ppm from the center and the NJO byte is 2 bytes) Band) to 40.1434 Gbit / s (the band when the OTN system side clock is +20 ppm from the center and PJO is 3 bytes). On the other hand, for the 40 GbE client signal, the signal speed is 40.1528 Gbit / s (40.00 × (1027/1024) × (3808 × 4) / (3808 ×) considering the fixed stuff of 12 bytes and the PJO byte of 3 bytes. 4-12) at +100 ppm) to 40.1448 Gbit / s (40.00 × (1027/1024) × (3808 × 4) / (3808 × 4-12) at −100 ppm)). Therefore, it can be seen that the 40 GbE client signal can be accommodated in the OPU3 frame.

  FIG. 3 is a second example in the case of accommodating a 1024B / 1027B transcoded 40 GbE client signal. The difference from the first example of FIG. 2 is that the fixed stuff is 11 bytes, the PJO bytes (PJO1, PJO2, PJO3, and PJO4 in FIG. 3) are 4 bytes, and NJO (indicated as NJO1 in FIG. 3). Is 1 byte. In the accommodation example of FIG. 3, the bandwidth that can be accommodated by the justification process using the PJO byte and NJO byte is 40.1539 Gbit / s to 40.1409 Gbit / s, and the speed of the 40 GbE client signal is 40.1502 Gbit / s to 40.40. Since it becomes 1422 Gbit / s, it turns out that it can accommodate.

  FIG. 4 is a first example in the case of accommodating a 40 GbE client signal that is 512B / 513B or 1024B / 1026B transcoded. The accommodation example of FIG. 4 accommodates (inserts) FS of 27 bytes in the OPU3 payload for a 40 GbE client signal (denoted as D in FIG. 4) that has been 512B / 513B or 1024B / 1026B transcoded. And insert (define) 3 bytes of PJO bytes (denoted as PJO1, PJO2, and PJO3 in FIG. 4) into the OPU3 payload, and insert 2 bytes of NJO bytes (denoted as NJO1 and NJO2 in FIG. 4) into the OPU3 overhead. This is an example of (definition). Since the conversion ratios of 512B / 513B and 1024B / 1026B are the same, the signal speed accuracy adjustment can be made the same.

  FIG. 5 is a second example in the case of accommodating 40 GbE client signals that have been 512B / 513B or 1024B / 1026B transcoded. The difference from the first example in FIG. 4 is that the fixed stuff is 26 bytes, the PJO bytes (PJO1, PJO2, PJO3, and PJO4 in FIG. 5) are 4 bytes, and the NJO bytes (indicated as NJO1 in FIG. 5). ) Is 1 byte.

  In the present embodiment, the coding rules of 1024B / 1027B, 512B / 513B, and 1024B / 1026B have been described. However, the present invention is also applicable to client signals that are coded by other coding rules.

  In addition, the positions of the fixed stuff and the position of the PJO byte in FIGS. 2 to 5 are only examples, and the functions do not change even if they are inserted (mapped) in the OPU payload. Similarly, the NJO byte is functionally unchanged when it is inserted anywhere within the OPU overhead. Also, the OTU3e frame format in which the frame rate of the OTU3 frame is changed can be applied by changing the number of fixed stuff, PJO bytes, and NJO bytes.

  As described above, according to the present embodiment, an existing optical component (for example, a component based on the existing ITU-TG.709) is used without newly preparing an expensive optical component, and 41.25 Gbit ± 100 ppm. A 40 GbE client signal can be accommodated in an OTU3 frame of 43.018 Gbit / s ± 20 ppm (the bandwidth of the OPU3 payload is 40.15 Gbit / s ± 20 ppm).

  In the present embodiment, the optical digital transmission device 10 includes a code conversion unit 11, an FS rate adjustment unit 12, a justification processing unit 13, and a transmission unit 14, but the optical digital transmission device 10 includes a code conversion unit 11. The FS rate adjustment unit 12 and the justification processing unit 13 may be provided, and the transmission unit 14 may be mounted on another device different from the optical digital transmission device 10. The same applies to the code conversion unit 11, the FS rate adjustment unit 12, and the justification processing unit 13.

 A program for realizing each process of the optical digital transmitter 10 shown in FIG. 1 (the same applies to the optical digital receiver 20 shown in FIG. 2) is recorded on a computer-readable recording medium and recorded on the recording medium. Each process of the optical digital transmitter 10 described above may be performed by causing the computer system to read and execute the program. Here, the “computer system” may include an OS and hardware such as peripheral devices. For example, a “computer system” includes a plurality of separate devices, and some of the plurality of devices include “hardware” that implements a wireless function for communicating with other devices. May be included. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

1 is a configuration example of an optical digital transmission / reception system to which an optical digital transmission device 10 according to an embodiment of the present invention is applied. It is a figure which shows the accommodation (mapping) example of the 40GbE client signal to an OPU3 frame. It is a figure which shows the accommodation (mapping) example of the 40GbE client signal to an OPU3 frame. It is a figure which shows the accommodation (mapping) example of the 40GbE client signal to an OPU3 frame. It is a figure which shows the accommodation (mapping) example of the 40GbE client signal to an OPU3 frame. It is a system structural example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical digital transmission / reception system 10 Optical digital transmitter 11 Code conversion part 12 FS rate adjustment part 13 Justification process part 14 Transmission part 20 Optical digital receiver 21 Code conversion part 22 Restoration process part 23 Reception part

Claims (10)

An optical digital transmission device for accommodating a client signal in a transmission frame and transmitting it to a transmission line,
A code conversion unit that converts the coding rule of the client signal into another coding rule;
A first signal speed adjustment unit that adjusts the signal speed of the client signal after conversion into the other coding rule by inserting a fixed stuff for speed adjustment;
An optical digital transmission comprising: a second signal speed adjustment unit that adjusts the signal speed of the client signal after conversion into the other coding rule by inserting positive stuff and negative stuff for speed adjustment. apparatus. The transmission frame is
ITU-T G. The optical digital transmission device according to claim 1, wherein the transmission rate is an OTU3 frame having a transmission rate of 43.018 Gbit / s ± 20 ppm in accordance with 709. The client signal is
41.25 Gbit / s ± 100 ppm of 40 GbE,
The other encoding rule is:
3. The optical digital transmission device according to claim 2, wherein the optical digital transmission device is 1024B / 1027B. The client signal is
41.25 Gbit / s ± 100 ppm of 40 GbE,
The other encoding rule is:
3. The optical digital transmission device according to claim 2, wherein the optical digital transmission device is either 512B / 513B or 1024B / 1026B. The first signal speed adjustment unit includes:
Insert a 12-byte fixed staff,
The second signal speed adjustment unit is
The optical digital transmitter according to claim 3, wherein 3-byte positive stuff and 2-byte negative stuff are inserted. The first signal speed adjustment unit includes:
Insert 11 bytes of fixed staff,
The second signal speed adjustment unit is
4. The optical digital transmitter according to claim 3, wherein 4-byte positive stuff and 1-byte negative stuff are inserted. The first signal speed adjustment unit includes:
Insert a 27-byte fixed staff,
The second signal speed adjustment unit is
5. The optical digital transmitter according to claim 4, wherein 3-byte positive stuff and 2-byte negative stuff are inserted. The first signal speed adjustment unit includes:
Insert a 26 byte fixed stuff,
The second signal speed adjustment unit is
5. The optical digital transmitter according to claim 4, wherein 4-byte positive stuff and 1-byte negative stuff are inserted. An optical digital transmission / reception system comprising an optical digital transmission device and an optical digital transmission device for mutually transmitting / receiving client signals contained in a transmission frame,
The optical digital transmitter is
A code conversion unit that converts the coding rule of the client signal into another coding rule;
A first signal speed adjustment unit that adjusts the signal speed of the client signal after conversion into the other coding rule by inserting a fixed stuff for speed adjustment;
A second signal speed adjustment unit that adjusts the signal speed of the client signal after conversion into the other coding rule by inserting positive stuff and negative stuff for speed adjustment;
The optical digital receiver is
An optical digital transmission / reception system, wherein the client signal is restored from the transmission frame. An optical digital transmission method for accommodating a client signal in a transmission frame and transmitting it to a transmission line,
A code conversion step of converting the encoding rule of the client signal into another encoding rule;
A first signal speed adjustment step of adjusting a signal speed of the client signal converted into another coding rule by the code conversion step by inserting a fixed stuff for speed adjustment;
And a second signal speed adjustment step of adjusting the signal speed of the client signal converted into another coding rule by the code conversion step by inserting positive stuff and negative stuff for speed adjustment. Optical digital transmission method.

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