KR20010058240A - Optical Channel Overhead Allocation Method of SDH Signal in WDM Network - Google Patents

Abstract

PURPOSE: An Optical channel overhead insert method of synchronous digital hierarchy on wave-length division multiplex is provided to detect error occurred on WDM(Wave-length Division Multiplex) network from SDH(Synchronous Digital Hierarchy) network with utilizing RSOH(Regenerator Sector Over Head) of SDH signal of client signal as optical channel overhead of WDM network by using a new error information transmission method. CONSTITUTION: An optical channel overhead of the WDM network is transmitted to assign to un-occupied overhead among the SDH relay section overhead. Favorably even number parity byte of the WDM network is transmitted after more allocating to the un-occupied overhead. More favorably the even number parity byte is composed of even number parity bit of 8 section dividing optical channel overhead of WDM network.

Description

Optical Channel Overhead Allocation Method of SDH Signal in WDM Network in Synchronized Digital Threshold Signals

The present invention relates to a method of inserting an overhead of an intermediate section of an SDH signal when a client signal of a wavelength division multiplex (WDM) network is a synchronous digital hierarchy (SDH) signal.

Conventionally, when a synchronous digital hierarchy (SDH) signal is used as a client signal in a WDM network, the transmission quality is monitored using B1 bytes of RSOH (Regenerator Sector Overhead) in the SDH signal without providing fiber channel layer overhead. It is common to do it.

That is, in the relay section in the conventional SDH transmission network, the parity bit calculated by the Bit Interleaved Parity (BIP) -8 method is transmitted to 8 bits of the B1 byte, and the transmission quality is measured using the same. Recommendation G.907 of the International Telecommunication Union- Telecommunication Standardization Sector (ITU-T) recommends that B1 bytes be allocated to the relay section overhead in the SDH frame for interoperability. In addition, when the SDH signal is transmitted as a client signal through the WDM network, an unused overhead of RSOH in the SDH signal may be used as an overhead signal of the fiber channel layer.

However, when some RSOH in the SDH signal is used as a fiber channel overhead signal in the WDM network, the B1 byte used for the detection of transmission error in the SDH relay section should be corrected. As a result, when the SDH signal, which is a client signal, is finally output to the SDH device through the WDM network, it is not known whether an error occurs in the transmission section through the WDM network, thereby making it difficult to monitor and control the SDH signal.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, by adding a separate parity byte while transmitting the SDH signal without changing the B1 byte through the node in the WDM network, the optical channel overhead An object of the present invention is to provide an optical channel overhead insertion apparatus for a synchronous digital boundary signal in a wavelength division multiple network such that the byte inserted for the channel does not affect the B1 byte.

FIG. 1 is a diagram illustrating an optical channel overhead insertion method of a synchronous digital boundary signal in a wavelength division multiple network according to an embodiment of the present invention.

In order to achieve the above object, the present invention provides a method for inserting the optical channel overhead transmitted from the wavelength division multiplexing network to the SDH relay section, wherein the optical channel overhead of the wavelength division multiplexing network is not used among the SDH relay section overheads. It is characterized in that the transmission to the head.

Preferably, the even parity byte of the optical channel overhead of the wavelength division multiple network is further allocated to the unused overhead and then transmitted.

More preferably, the even parity byte is composed of even parity bits of eight sections divided by the optical channel overhead of the wavelength division multiplexing network.

Hereinafter, an apparatus for inserting an optical channel overhead of a synchronous digital boundary signal in a wavelength division multiple network according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In the WDM (Wave-length Division Multiplexing) network, multiple optical signals of different wavelengths are transmitted through one optical cable in terms of transmission band extension. Client signals accommodated in such a WDM network may be signals of a synchronous digital layer (SDH) or another signal. Importantly, the WDM network can be thought of as a kind of transmission line, so the client signals accepted in the WDM network must be transparent from end to end.

In WDM network, transmission overhead for maintenance signal processing should be provided for maintenance between WDM nodes. If the client signal is SDH signal, SDH relay section is overwritten for maintenance signal processing of fiber channel layer set between WDM nodes. It is very advantageous in terms of transmission efficiency to use the overhead which is not used among the heads as the fiber channel overhead.

In the optical transmission device of the synchronous digital layer, as indicated in ITU-T G.707, one byte is allocated as B1 byte for monitoring the performance of the SDH relay section. This is Bit Interleaved Parity 8 (BIP-8) code with even parity, and after scrambling, BIP-8 calculates all the bits of the previous Synchronous Transport Module-N (STM-N) frame and places them in the B1 byte position of the current frame before scrambling. Put it. At this time, one frame is divided into eight blocks, parity check is performed, and the result is stored in eight bits of the B1 byte. The SDH signal containing the B1 byte is transmitted to the next relay, and the next relay checks the parity check on the frame of the transmitted SDH signal and compares the result with the parity check in the transmitted B1 byte to determine whether there is an error in the transmitted SDH signal. do. The parity check result performed in the repeater is loaded on the B1 byte in the SDH signal and transmitted to the next repeater.

In general, when the SDH signal transmitted through the WDM network exits the WDM network and arrives at the SDH network, to detect an error through the B1 byte, the B1 created just before being transmitted to the WDM network without changing the B1 byte in the WDM network You must keep the value. To this end, the WDM network uses the unused overhead of the SDH relay section as the fiber channel overhead.In order to perform the network monitoring control function independently of the WDM network in the SDH network, the error generated in the WDM network is corrected. Must be transparent to the SDH network.

The present invention provides a method of transmitting unused overhead among SDH relay section overheads as the optical channel overhead of the WDM network and transmitting maintenance information between relay sections set between SDH end nodes without change.

For this purpose, in order to invalidate the parity value change due to the inserted optical channel overhead without changing the B1 byte, inserting a separate parity byte only for the inserted overhead does not affect the B1 byte.

FIG. 1 is a diagram illustrating an optical channel overhead insertion method of a synchronous digital boundary signal in a wavelength division multiple network according to an embodiment of the present invention. First, in the drawing, the fiber channel overhead byte is inserted using the unused overhead among the relay section overheads in the SDH (11). Let the inserted Fiber Channel overhead byte be Z _{OH, i} . Where i = 1, 2,... Indicates that multiple bytes have been allocated for fiber channel overhead.

After the optical channel overhead byte Z _{OH, i} is inserted in this manner, the optical channel overhead byte is divided into eight blocks, and eight even parity bits for the same are generated and inserted into the parity byte Z _P (12). This fiber channel overhead byte and parity byte are inserted in the unused overhead of the relay section overhead. Therefore, since even parity is inserted, B1 bytes are preserved.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, according to the present invention, an error generated in the WDM network can be detected in the SDH network while using RSOH of the SDH signal as the client signal as the optical channel overhead of the WDM network by using the new error information transmission scheme. This ensures a fiber channel overhead channel without increasing the transmission rate or creating a separate physical channel.

Claims (3)

In the method for inserting the optical channel overhead transmitted from the wavelength division multiplex network to the SDH relay section, And transmitting the optical channel overhead of the wavelength division multiplexing network to an unused overhead of the SDH relay section overhead and transmitting the optical channel overhead. 2. The method of claim 1, wherein the even parity byte of the optical channel overhead of the wavelength division multiple network is further allocated to the unused overhead and then transmitted. . 3. The method of claim 2, wherein the even parity byte comprises an even parity bit of eight sections divided by the optical channel overhead of the wavelength division multiplex network.