KR20060062304A - Method for transferring frame between sdh network and ethernet and apparatus thereof - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting a synchronous transmission module frame through Ethernet in a simpler process while efficiently using a bandwidth between a synchronous digital layer (hereinafter referred to as SDH) network and Ethernet. The method includes: detecting information and payload data necessary for ensuring reliability of data in a synchronous transmission module (STM) frame received from a synchronous digital layer network; Generating an Ethernet frame including necessary information and payload data detected in a predetermined field; And transmitting the generated Ethernet frame to Ethernet.

Description

Method for transferring frame between synchronous digital layer network and Ethernet {Method for transferring frame between SDH network and Ethernet and apparatus}

1 is a block diagram illustrating a network including a frame forwarding apparatus according to an embodiment of the present invention.

2 is a structural diagram of an STM-n frame.

3 is a structural diagram of overhead of an STM-n frame.

4 is a functional definition of the overhead of an STM-n frame.

5 is a structural diagram of the Ethernet frame.

6 is a structural diagram of an Ethernet frame generated according to the present invention.

7 is a flowchart illustrating a frame forwarding method according to another embodiment of the present invention.

The present invention relates to a method and apparatus for transferring a frame between a synchronous digital layer (hereinafter referred to as SDH) network and Ethernet.

SDH networks are internationally equivalent to Synchronous Optical Networks (SONET) as a standard technology for synchronous data transmission on a transmission medium. This is because the process of multiplexing the hierarchical signals to a synchronous transport module (hereinafter, referred to as STM) -1 employs a synchronous multiplexing structure. The SDH network is a medium-to-long distance network of several tens of kilometers or more, and aims to safely transmit data to a destination, and continuously transmits frames along a path set by a manager of a transmission network.

Ethernet is a local area network, and aims to efficiently transfer data on a local area network, which is an asynchronous network, and determines a switching path at each node based on address information included in a frame.

However, in recent years, as physical technologies are developed, the distance that can transmit data through Ethernet has been extended to several tens of kilometers, and as the use of the Internet increases, the proportion of Ethernet in the information and communication network is increasing.

Therefore, technologies for interconversion between Ethernet frames or IP (Internet Protocol) packets and STM frames transmitted through the SDH network have been announced. The representative technology is EoS (Ethernet over SDH) technology. EoS is a technology that includes Ethernet frame in STM frame and delivers it through SDH network. In other words, EoS includes the Ethernet frame in the payload of the Generic Framing Procedure (GFP) frame and attaches the GFP header to the payload of the STM frame. At this time, Ethernet frames passing through the same path in the SDH network are allocated to the same multiplexed channel, virtual concatenation technology is used to efficiently use the bandwidth, and link capacity is allocated for flexible bandwidth allocation. Adjuestment Scheme technology is used.

In this way, EoS is not only very complicated to load Ethernet data into the STM frame, but also has a large bandwidth loss due to the addition of the GPF header and STM overhead.

An object of the present invention is to provide a method and apparatus capable of delivering a frame in a simpler process while efficiently using bandwidth between a synchronous digital hierarchy (SDH) network and Ethernet.

Another object of the present invention is to provide a frame transfer method and apparatus capable of transferring a synchronous transmission module (STM) frame between a synchronous digital hierarchy (SDH) network and an Ethernet.

In order to achieve the above technical problem, the present invention includes the steps of detecting information and payload data necessary to ensure the reliability of the data in the synchronous transmission module (STM) frame received from the synchronous digital layer network; Generating an Ethernet frame including necessary information and payload data detected in a predetermined field; It provides a frame transfer method comprising the step of transmitting the generated Ethernet frame to the Ethernet.

The information detected to ensure data reliability preferably includes automatic protection switching information K1 and K2 and synchronization state information S1 defined in the multiplexer section overhead. The predetermined field is preferably defined as a payload field of the Ethernet frame. In addition, in the predetermined field, information about a transmission rate of a synchronous digital layer frame, display information for distinguishing a first Ethernet frame and a last Ethernet frame among a plurality of Ethernet frames corresponding to one synchronous transmission module frame, and an order for maintaining an order of an Ethernet frame It is preferable to further include serial number information.

According to an aspect of the present invention, there is provided a frame format conversion unit for converting a received synchronous transmission module frame to an Ethernet frame format when a synchronous transmission module (STM) frame is received from a synchronous digital layer network; Provided is a frame transfer apparatus including a transmitter for transmitting an Ethernet frame output from a frame format converter to the Ethernet.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a network including a frame forwarding apparatus according to an embodiment of the present invention. Referring to FIG. 1, the network includes Node A 100, Ethernet 110, and Ethernet 110 and SDH network (not shown) corresponding to a junction between an SDH network (not shown) and Ethernet 110. Node B (120) corresponding to the junction between the.

When the Node A 100 receives a Synchronous Transport Module (hereinafter, referred to as STM) -n frame through an SDH network (not shown), the Node A 100 converts the received STM-n frame into an Ethernet frame and converts the Ethernet (110). To be sent. N may be defined as 1, 4, 16, 64, or the like as an integer.

To this end, the node A 100 includes an STM-n frame / Ethernet frame converter 101 and an Ethernet frame transmitter 102.

When the STM-n frame / Ethernet frame converter 101 receives the STM-n frame, the STM-n frame / Ethernet frame converter 101 converts the received STM-n frame into an Ethernet frame format. Therefore, the STM-n frame / Ethernet frame converter 101 may be defined as a frame format converter.

The STM-n frame is as shown in FIG. That is, referring to Fig. 2, the STM-n frame has a three-row, nine-column, n-byte player section overhead, one-row, nine-column, n-byte pointer, and five-row, nine-column, It consists of a total of 9 rows x 270 columns x n bytes, including n bytes of multiplexer section overhead and 9 rows x 261 columns x n bytes of payload.

Among them, the structure of the overhead is as shown in FIG. 3, and the function of the overhead is as defined in FIG. 4. The player section overhead is information used by the player and tracks and monitors errors occurring while data is transferred between the player and the player. The multiplexer section overhead tracks and monitors the information used by the multiplexer, errors that occur while data is passing between the multiplexer and the multiplexer, and informs the other multiplexer of information for automatic protection switching. .

The SDH network transmitting the STM-n frame guarantees the reliability of the data and, when a serious error occurs in the transmitted data, determines that there is a problem in the transmission path and has a function of switching to the protection path.

Therefore, in order to ensure reliability of the corresponding data even when the STM-n frame is transmitted through the Ethernet 110, the STM-n frame / Ethernet frame converter 101 is transmitted through the overhead of the received STM-n frame. In order to ensure the reliability of the data of the information necessary to detect the information.

The overhead of the STM-n frame is divided into a player section overhead and a multiplexing section overhead, as shown in FIG. 2, and the Ethernet 110 is regarded as one multiplexer section. Therefore, the STM-n frame / Ethernet frame converter 101 is information necessary to ensure the reliability of the data, and is used for data error detection and protection switching included in the multiplexer section overhead of the STM-n frame. Detect related information. Referring to FIG. 3, B3, K1, K2, S1, and M1 in the multiplexer section overhead correspond to information related to the data error detection and protection switching.

However, among the data, B2 indicates parity information on payload of the STM-n frame and is used to detect a parity error of payload data. However, this overlaps with the error detection function provided by the Frame Check Sequence (FCS) information of the Ethernet frame. The FCS information is information for a cyclic redundancy check (CRC) check on a frame and has a stronger error detection function than the parity check. Therefore, the STM-n frame / Ethernet frame converting unit 101 does not detect the B2 information.

In addition, the M1 informs the counterpart multiplexer of the number of errors generated as a result of the parity check. Since this information is not necessary when B2 information is not used, the STM-n frame / Ethernet frame converter 101 Also does not detect the M1 information.

Therefore, the STM-n frame / Ethernet frame conversion unit 101 guarantees reliability of the data only among the automatic protection switching information K1 and K2 and the synchronization state information S1 information among the multiplexer section overhead of the inputted STM-n frame. It is detected as essential information.

On the other hand, the Ethernet frame is as shown in FIG. That is, it consists of an 8-byte preamble field, an 14-byte Ethernet header field, an 46- to 1500-byte Ethernet payload field, and a 4-byte FCS field.

The Ethernet header field includes a six-byte destination address field, a six-byte source address field, and a two-byte type field. The type field is a field in which information indicating the type of a frame to be transmitted is defined and may be defined using a predetermined value.

The STM-n frame / Ethernet frame conversion unit 101 shows the detected K1, K2, S1 information and payload data of the STM-n frame in the payload field of the Ethernet frame as shown in FIG. Include as indicated.

In this case, since the payload length of the Ethernet frame is limited to 1500 bytes, the payload of one STM-n frame is divided into several Ethernet frames, and the K1, K2, and S1 information is divided with the STM-n frame. Payload data is divided into separate areas. That is, K1, K2, and S1 information is included in the STM header region added to the payload data of the divided STM-n frame. The STM header area may be defined as a header area corresponding to payload data of the divided STM-n frame. The STM header area includes SDH data rate information, which is necessary for configuring the STM-n frame again at the Node B 120 exiting from the Ethernet 110 to the SDH network (not shown) in addition to the K1, K2, and S1 information. The display apparatus may further include indication information for distinguishing a first Ethernet frame and a last Ethernet frame among a plurality of Ethernet frames corresponding to the payload of one STM-n frame, and serial number information to maintain the order of the frames. The SDH rate information, the first Ethernet frame and last Ethernet frame indication information, and serial number information are generated at node A (100).

The Destination Address field in the Ethernet Header field then contains the Ethernet address of Node B 120, the Source Address field contains the Ethernet address of Node A 100, and the Type field contains the STM-n frame in the currently transmitting frame. Include type information indicating that this is included.

When the Ethernet frame including the information on the STM-n frame is generated as described above, the STM-n frame / Ethernet frame converter 101 transmits the Ethernet frame generated according to the present invention to the Ethernet frame transmitter 102. .

The Ethernet frame transmitter 102 transmits an Ethernet frame including information about the STM-n frame to the Ethernet 110. As such, Node A (100) is a node used for the STM-n frame to enter the Ethernet (110).

When the Node B 120 receives an Ethernet frame having a format as shown in FIG. 6 through the Ethernet 110, the Node B 120 converts the received Ethernet frame into an STM-n frame format. The node B 120 includes an Ethernet frame receiver 121 and an Ethernet frame / STM-n frame converter 122.

The Ethernet frame receiving unit 121 receives an Ethernet frame transmitted from the Ethernet 110. If it is recognized that the STM-n frame is included in the received Ethernet frame based on the information defined in the type field of the received frame, the Ethernet frame receiving unit 121 converts the received Ethernet frame into an Ethernet frame / STM-n frame conversion unit. Transmit to 122.

Since the Ethernet frame / STM-n frame converter 122 has a format as shown in FIG. 6, the payload data of the divided STM-n frames contained in the payload field of the Ethernet frame, K1 information, K2 information, S1 information, STM rate information, first Ethernet frame indication information, last Ethernet frame indication information, and serial number information included in the STM header are respectively detected.

The Ethernet frame / STM-n frame converter 122 defines the multiplexer section overhead of the STM-n frame using the detected K1, K2, and S1 information, and provides it from a provision server, not shown. The pointer information of the STM-n frame is defined based on the time slot information, and the payload of the STM-n frame is determined based on the detected payload data of the divided STM-n frame, the Ethernet frame indication information, and the serial number information. Create a defined STM-n frame. Therefore, the Ethernet frame / STM-n frame converter 122 may be defined as a frame format converter.

The player section overhead in the generated STM-n frame may be defined by communication with the next node (not shown) that will receive the generated STM-n frame. The next node is the node connected to the SDH network (not shown).

Accordingly, the Node B 120 may be defined as a node from which the STM-n frame exits from the Ethernet 110 to the SDH network and leaves the Ethernet 110.

7 is a flowchart illustrating a frame forwarding method according to another embodiment of the present invention. FIG. 7 illustrates a case for transmitting an STM-n frame generated in an SDH network through Ethernet.

That is, when the STM-n frame is received from the SDH network (701), the multiplexer interval overhead is detected in the received STM-n frame (702).

Automatic protection switching information and synchronization state information are detected from the information defined in the detected multiplexer section overhead (step 703). The automatic protection switching information is K1 and K2 information as described in the STM-n frame / Ethernet frame converter 101 of FIG. 1, and the synchronization state information is S1 information. The automatic protection switching information and the synchronization state information are included in the information necessary to guarantee the reliability of the transmitted data. The information necessary for guaranteeing the reliability of the data in the multiplexer section overhead further includes B2 and M1 information in addition to the K1, K2, and S1 information. However, since the B2 and M1 information are not necessary information for the same reason as described in FIG.

The detected auto-protection switching information and the synchronization state information are included in the Ethernet payload field together with the payload data detected in the STM-n frame (704). At this time, since the length of the Ethernet payload is limited to 1500 bytes as described in FIG. 6, the payload of the detected STM-n frame cannot be loaded in one Ethernet payload. Therefore, the node A 100 divides the payload data of one STM-n frame and includes it in the Ethernet payload field of the plurality of Ethernet frames, while allowing the node B 120 to reconstruct the STM-n frame. Ethernet payload by generating display information to distinguish the first Ethernet frame and the last Ethernet frame among the plurality of Ethernet frames corresponding to the STM-n frame, serial number information to maintain the order of the frames, and transmission rate information of the STM-n frame Include more in the field. Rate information of the K1, K2, S1, and STM-n frames, first Ethernet frame indication information and last Ethernet frame indication information, and serial number information are included in the payload of the divided STM-n frame as shown in FIG. Include in the added STM header area.

The Ethernet header field is defined (705). The destination address in the header field is defined as the Ethernet address of node B 120 to transmit SDH network (not shown) STM-n frames from Ethernet 110, and the source address is defined as the Ethernet address of node A 100. The type field defines previously promised information indicating that the STM-n frame is included in the currently transmitted Ethernet frame.

When the Ethernet frame is defined as such, an Ethernet frame having a format as shown in FIG. 6 is generated (706). The generated Ethernet frame is sent to the Ethernet (110).

The frame transfer method according to the present invention can be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and also carrier wave (for example, transmission over the Internet). It is also included to be implemented in the form of. The computer readable recording medium can also be distributed over computer systems connected over a computer network so that the computer readable code is stored and executed in a distributed fashion.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, according to the present invention, the frame and the frame from the synchronous digital layer network to Ethernet by detecting the information and payload data necessary to ensure reliability in the STM-n frame is included in the payload field of the Ethernet frame and sent to Ethernet. In addition to simplifying the delivery process, bandwidth can be efficiently utilized by minimizing additional data.

Claims (13)

In the frame transfer method between a synchronous digital layer (SDH) network and Ethernet, Detecting information and payload data necessary to ensure data reliability in a synchronous transmission module (STM) frame received from the synchronous digital layer network; Generating an Ethernet frame including the detected necessary information and payload data in a predetermined field; And transmitting the generated ethernet frame to the ethernet. 2. The frame transfer of claim 1, wherein the information necessary for guaranteeing the reliability of the data includes information related to error detection and protection switching of data defined in the multiplexer section overhead of the synchronous transmission module frame. Way. The method according to claim 1 or 2, wherein the information necessary for guaranteeing the reliability of the data is determined from the information related to error detection and protection switching of data defined in the multiplexer section overhead of the synchronous transmission module frame. And information except for information having a function of overlapping with information defined in a field other than the predetermined field. The frame transfer method according to claim 3, wherein the information detected to ensure data reliability includes automatic protection switching information (K1, K2) and synchronization state information (S1) defined in the multiplexer section overhead. Way. 5. The method of claim 4, wherein the predetermined field is an Ethernet payload field. The method of claim 5, wherein generating the Ethernet frame, Dividing payload data detected in the synchronous transmission module frame to be included in an Ethernet payload field of a plurality of Ethernet frames; Generating rate information of the synchronous digital layer frame, indication information for distinguishing a first Ethernet frame and a last Ethernet frame among the plurality of Ethernet frames, and serial number information for maintaining an order of the plurality of Ethernet frames; Transfer rate information, the display information, the serial number information, the automatic protection switching information (K1, K2), and the synchronization state information (S1) of the generated synchronous digital layer frame to payload data of the divided synchronous transmission module frame. And including the corresponding header area. The method of claim 1, wherein the predetermined field is an Ethernet payload field, The Ethernet frame generation step, Dividing payload data detected in the synchronous transmission module frame to be included in an Ethernet payload field of a plurality of Ethernet frames; Generating rate information of the synchronous digital layer frame, indication information for distinguishing a first Ethernet frame and a last Ethernet frame among the plurality of Ethernet frames, and serial number information for maintaining an order of the plurality of Ethernet frames; Transfer rate information, the display information, the serial number information, the automatic protection switching information (K1, K2), and the synchronization state information (S1) of the generated synchronous digital layer frame to payload data of the divided synchronous transmission module frame. And including the corresponding header area. 2. The method of claim 1, further comprising defining type information included in a header field of the Ethernet frame to indicate that the Ethernet frame includes the synchronous transmission module frame. In the frame transfer device between a synchronous digital layer (SDH) network and Ethernet, A frame format conversion unit converting the received synchronous transmission module frame into an Ethernet frame format when receiving a synchronous transmission module (STM) frame from the synchronous digital layer network; And a transmitter for transmitting the Ethernet frame output from the frame format converter to the Ethernet. The method of claim 9, wherein the frame format converter, Detecting information and payload data necessary for guaranteeing the reliability of the frame in the received synchronous transmission module frame; And outputting an Ethernet frame including information and payload data necessary for the detected reliability correction in a predetermined field. The apparatus of claim 10, wherein the information necessary for guaranteeing the reliability of the frame includes auto-protection switching information and synchronization state information included in the multiplexer section overhead of the synchronous transmission module frame. 12. The apparatus of claim 10 or 11, wherein the predetermined field is a payload field of the Ethernet frame. The method of claim 12, wherein the frame format conversion unit, Divide the payload data detected in the synchronous transmission module frame into a payload field of a plurality of Ethernet frames, Generating synchronous digital layer data rate information, indication information for distinguishing a first Ethernet frame and a last Ethernet frame among the plurality of Ethernet frames, and serial number information for maintaining an order of frames; The automatic protection switching information, the synchronization status information, the synchronous digital layer transmission rate information, display information for distinguishing the Ethernet frame, and the serial number in a synchronous transmission module frame header area corresponding to the payload data of the divided synchronous transmission module frame. Frame delivery device comprising the information.

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