JP2008153956A - Data transmission system, data transmitter, and data receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transmission system for efficiently transmitting data by reducing an overhead of data transmission. <P>SOLUTION: In the data transmission system for collectively storing a plurality layer 2 packets generated by dividing a layer 3 packet in a transmission frame for transmitting a physical layer, a transmission frame 30 has an identification information storage area for storing L3SN (Layer 3 Sequence Number) of L3PDU (Layer 3 Protocol Data Unit) to which L2PDU (Layer 2 Protocol Data Unit) to be stored in a self-frame belongs, and the identification information storage area associates a plurality of L2PDUs with one L3SN and collectively stores common L3SNs when the L3SNs are common between L2PDUs to be stored in the transmission frame 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a data transmission system, a data transmission apparatus, and a data reception apparatus that transmit data by dividing a layer 3 packet into layer 2 packets.

  As one technique for transmitting and receiving data on a network, a layer 3 packet is divided into layer 2 packets, and a plurality of layer 2 packets generated by division are stored together in a transmission frame and data is transmitted via a physical layer. There is a data transmission system that performs transmission. In such a data transmission system, it is desired to efficiently transmit data by reducing the amount of data transmission.

  In the communication system described in Patent Document 1, a transmission-side apparatus divides an upper layer parent packet into short segments and transmits the segment together with segmentation information. Further, the receiving side device assembles the upper layer parent packet by concatenating the received segments using the segmentation information. In this communication system, each divided segment includes a parent packet sequence number for identifying the parent packet and a segment sequence number for identifying each segment. On the receiving side, when assembling the parent packet, all the segments that make up the parent packet are accurate regardless of whether or not all of the parent packets with a parent packet sequence number smaller than the parent packet are sent to the upper layer. If it can be received, the parent packet is assembled and sent to the upper layer.

JP 2005-229575 A

  However, in the above conventional technique, since the parent packet sequence number for identifying the parent packet is set in all the segments generated by dividing the parent packet, there is a problem that the overhead of data transmission increases. .

  The present invention has been made in view of the above, and an object of the present invention is to obtain a data transmission system, a data transmission device, and a data reception device that efficiently perform data transmission by reducing data transmission overhead.

  In order to solve the above-described problems and achieve the object, the present invention stores a plurality of layer 2 packets generated by dividing a layer 3 packet in a transmission frame for transmitting the physical layer and transmitting data. In the transmission system, the transmission frame has an identification information storage area for storing identification information of a layer 3 packet to which the layer 2 packet stored in the own frame belongs, and the identification information storage area is included in the transmission frame. When the identification information is common among the layer 2 packets stored in the network, a plurality of layer 2 packets are associated with one identification information, and the common identification information is stored together. To do.

  According to the present invention, when the identification information of the layer 3 packet is common among the layer 2 packets stored in the transmission frame, the common identification information is stored together, thereby reducing the overhead of data transmission. There is an effect that data transmission can be performed efficiently.

  Hereinafter, embodiments of a data transmission system, a data transmission device, and a data reception device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a data transmission system according to Embodiment 1 of the present invention. The data transmission system 100 is a system that transmits a plurality of segments generated by dividing a parent packet, and includes a data transmission device 1, a data reception device 2, and a transmission path 7.

  The data transmission device 1 is a device that transmits data to the data reception device 2, and includes a layer 3 transmission unit 3, a layer 2 transmission unit 10, and a physical layer control unit 5. The data reception device 2 is a device that receives data from the data transmission device 1, and includes a layer 3 reception unit 4, a layer 2 reception unit 20, and a physical layer control unit 6. The transmission path 7 connects the data transmission device 1 and the data reception device 2 and transmits data from the data transmission device 1 to the data reception device 2.

  In the data transmission device 1, the layer 3 transmission unit 3 and the layer 2 transmission unit 10 are connected, and the layer 2 transmission unit 10 and the physical layer control unit 5 are connected. Further, in the data receiving device 2, the layer 3 receiving unit 4 and the layer 2 receiving unit 20 are connected, and the layer 2 receiving unit 20 and the physical layer control unit 6 are connected. The physical layer control unit 5 of the data transmission device 1 and the physical layer control unit 6 of the data reception device 2 are connected via a transmission path 7.

  The layer 3 transmission unit 3 of the data transmission device 1 transmits a layer 3 protocol data unit (hereinafter referred to as L3 PDU) to the layer 2 transmission unit 10. The layer 2 transmission unit 10 divides the L3 PDU from the layer 3 transmission unit 3 into layer 2 protocol data units (hereinafter referred to as L2 PDUs), and packs the divided L2 PDUs into a transmission frame 30 and transmits them to the physical layer control unit 5 . The layer 2 transmission unit 10 includes a division unit 11, a buffer unit 12, a scheduling unit 13, a transmission frame generation unit 14, and a retransmission control unit 15.

  The dividing unit 11 is connected to the layer 3 transmitting unit 3 and the buffer unit 12. The buffer unit 12 is connected to the scheduling unit 13 and the transmission frame generation unit 14, and the scheduling unit 13 is connected to the retransmission control unit 15. The transmission frame generation unit 14 and the retransmission control unit 15 are each connected to the physical layer control unit 5.

  The division unit 11 divides the L3 PDU received from the layer 3 transmission unit 3 into L2 PDUs and inputs the L2 PDUs to the buffer unit 12. The buffer unit 12 has a buffer function for accumulating and managing L2 PDUs generated (divided) by the dividing unit 11. The buffer unit 12 inputs the L2 PDU determined to be transmitted based on the instruction from the scheduling unit 13 to the transmission frame generation unit 14.

  The scheduling unit 13 has a scheduling function for determining an L2 PDU to be transmitted to the data receiving device 2. The scheduling unit 13 determines the transmission timing (transmission schedule) of the L2 PDU to be transmitted to the data reception device 2 based on the L2 PDU accumulated in the buffer unit 12 and the instruction from the retransmission control unit 15. The scheduling unit 13 instructs the buffer unit 12 to transmit L2 PDUs to be transmitted to the data receiving device 2.

  The transmission frame generation unit 14 packs the L2 PDU sent from the buffer unit 12 into a transmission frame 30 that is transmitted in the transmission path 7 (physical layer transmission path) to generate a transmission frame. The transmission frame generation unit 14 inputs the generated transmission frame 30 to the physical layer control unit 5.

  When an error occurs in the transmission frame 30 in the layer 2 receiving unit 20, the retransmission control unit 15 performs retransmission control when retransmitting the L2 PDU included in the transmission frame 30 in which the error has occurred. The retransmission control unit 15 receives information indicating that an error has occurred in the transmission frame 30 sent from the layer 2 reception unit 20 via the physical layer control unit 5, and determines an L2 PDU to be retransmitted. The retransmission control unit 15 instructs the scheduling unit 13 on the L2 PDU to be retransmitted. The physical layer control unit 5 performs transmission control when transmitting the transmission frame 30 generated by the layer 2 transmission unit 10 to the data reception device 2 via the transmission path 7.

  The physical layer control unit 6 of the data receiving apparatus 2 performs reception control when receiving the transmission frame 30 from the data transmitting apparatus 1 via the transmission path 7. The layer 2 reception unit 20 is opposed to the layer 2 transmission unit 10 via a lower layer (physical layer), and receives the transmission frame 30 from the layer 2 transmission unit 10 via the physical layer control unit 6. The layer 2 receiving unit 20 assembles L2 PDUs included in the received transmission frame 30 to generate L3 PDUs. The layer 2 reception unit 20 includes an error determination unit 21, a transmission frame decomposition unit (layer 2 packet extraction unit) 22, and an assembly unit (layer 3 packet generation unit) 23.

  The error determination unit 21 is connected to the physical layer control unit 6, and the assembly unit 23 is connected to the layer 3 reception unit 4. The error determination unit 21 and the assembly unit 23 are connected via the transmission frame decomposition unit 22.

  The error determination unit 21 has an error determination function that determines (inspects) the presence or absence of an error in the transmission frame 30 received from the physical layer control unit 6. The error determination unit 21 inputs the transmission frame 30 having no error to the transmission frame decomposition unit 22 and notifies the data transmission device 1 of information on the transmission frame 30 having an error.

  The transmission frame decomposition unit 22 decomposes the transmission frame 30 from the error determination unit 21 and extracts packed L2 PDUs. The transmission frame decomposition unit 22 inputs the extracted L2 PDU to the assembly unit 23. The assembling unit 23 assembles the L2 PDU from the transmission frame decomposing unit 22 into an L3 PDU and transmits the L3 PDU to the layer 3 receiving unit 4. The layer 3 reception unit 4 receives the L3 PDU from the layer 3 transmission unit 10 via the layer 2 transmission unit 10, the physical layer control unit 5, the transmission path 7, the physical layer control unit 6, and the layer 2 reception unit 20.

  Next, an operation procedure of the data transmission system 100 will be described with reference to FIGS. Here, as the operation procedure of the data transmission system 100, the operation procedure of the data transmission device 1 will be described, and then the operation procedure of the data reception device 2 will be described.

  FIG. 2 is a flowchart showing the operation procedure of the data transmitting apparatus, and FIG. 3 is an explanatory diagram for explaining the operation procedure of the data transmitting apparatus. When receiving the L3 PDU from the layer 3 transmitting unit 3 (step S10), the layer 2 transmitting unit 10 receives the L3 PDU sequence number (hereinafter referred to as L3SN (Layer 3 Sequence Number)) (identification) for the dividing unit 11 to identify each L3 PDU. Information) is numbered, and the L3 PDU is divided into L2 PDUs (step S20). FIG. 3 shows a case where the dividing unit 11 sets (numbering) L3SN = N (N is a natural number).

  Further, the dividing unit 11 assigns an L2 PDU sequence number (hereinafter referred to as L2SN) for identifying each L2 PDU to each L2 PDU generated by the dividing process. The dividing unit 11 adds (sets) this L2SN as ancillary information in the L2 PDU (step S30). For example, the dividing unit 11 sets L2SN = n (n is a natural number), L2SN = n + 1, and L2SN = n + 2 for each L2PDU. Furthermore, the dividing unit 11 adds (sets) information (flag) indicating the end of the L3 PDU to the L2 PDU that is the end of the L3 PDU (L3SN = N) (step S40).

  The dividing unit 11 transfers the generated L2PDU together with the L3SN (L3SN information) to the buffer unit 12. Thereafter, the buffer unit 12 stores and manages the L3SN and the L2 PDU until transmission of the transmission frame 30 corresponding to the L3 PDU is completed. An L2 PDU buffer 17 in FIG. 4 indicates an L2 PDU that is buffered by the buffer unit 12.

  The transmission timing of the LP2DU accumulated in the buffer unit 12 is determined by the scheduling unit 13. The scheduling unit 13 instructs the buffer unit 12 on the L2 PDU determined to be transmitted. Based on the instruction from the scheduling unit 13, the buffer unit 12 transfers the L2 PDU determined to be transmitted to the transmission frame generation unit 14 together with the L3SN corresponding to each L2 PDU. The transmission frame generation unit 14 packs the L2 PDU from the buffer unit 12 into a transmission frame 30 for transmitting the transmission path 7.

  Here, the configuration of the packed transmission frame 30 will be described. FIG. 4 is a diagram illustrating an example of a configuration of a transmission frame created by the data transmitting apparatus according to the first embodiment. The transmission frame generation unit 14 generates the transmission frame 30 using the L2 PDU transferred from the buffer unit 12 and the sequence number (L3SN) of the L3 PDU to which each L2 PDU belongs.

  In FIG. 4, the transmission frame generation unit 14 transmits four L2 PDUs of L2 PDU (L2SN = n−1) of “L3SN = N−1” and L2 PDU (L2SN = n, n + 1, n + 2) of “L3SN = N”. The case where it packs in the frame 30 is shown.

  The transmission frame generation unit 14 configures the transmission frame 30 by the L3SN (identification information storage area) of the L3 PDU and the L2 PDU to which the L2SN is assigned. In the transmission frame 30, each data is arranged in the order of L2PDU including L3SN and L2SN of L3PDU. At this time, the transmission frame generation unit 14 arranges the L3SN only in the first L2 PDU for the L2PDU having the same L3SN, and does not arrange the L3SN in the L2PDU having the same L3SN as the L2PDU. In other words, the transmission frame generation unit 14 generates a transmission frame 30 by putting together L3SNs common to L2 PDU groups into one for each L2 PDU group and arranging them at the head of each L2 PDU group (step S50).

  Here, the data in the transmission frame 30 is “L3SN = N−1”, L2PDU (L2SN = n−1), “L3SN = N”, L2PDU (L2SN = n), L2PDU (L2SN = n + 1), L2PDU (L2SN). = N + 2). The transmission frame 30 generated by the transmission frame generation unit 14 is transmitted to the data reception device 2 via the physical layer control unit 5 (step S60).

  Next, an operation procedure of the data receiving device 2 will be described. FIG. 5 is a flowchart showing the operation procedure of the data receiving apparatus, and FIG. 6 is an explanatory diagram for explaining the operation procedure of the data receiving apparatus.

  The transmission frame 30 transmitted by the physical layer control unit 5 is sent to the physical layer control unit 6 via the transmission path 7 and received by the physical layer control unit 6. The physical layer control unit 6 transfers the received transmission frame 30 to the layer 2 reception unit 20.

  The transmission frame 30 from the physical layer control unit 6 is received by the error determination unit 21 of the layer 2 reception unit 20 (step S110). The error determination unit 21 determines whether there is an error in the transmission path 7 of the transmission frame 30 received from the physical layer control unit 6. As an error check method, for example, a redundant code for error detection is given to the transmission frame 30 on the transmission side (data transmission apparatus 1), and the redundant code is checked on the reception side (error determination unit 21). To do.

  When the error determination unit 21 detects that an error has occurred in the error determination, the error determination unit 21 transmits information indicating that there is an error in the transmission frame 30 to the data transmission device 1. If the error determination unit 21 does not detect that an error has occurred in the error determination, the error determination unit 21 transfers the transmission frame 30 having no error to the transmission frame decomposition unit 22. Here, the error determination unit 21 transmits an ACK to the data transmission device 1 as an error determination result, for example, when no error occurs, and transmits a NACK to the data transmission device 1 when an error occurs. To do.

  The transmission frame decomposition unit 22 decomposes the transmission frame 30 from the error determination unit 21, and extracts the packed L2 PDU and the L3SN of the L3 PDU corresponding to this L2 PDU (step S120). The transmission frame decomposing unit 22 inputs the extracted L2 PDU and the L3SN corresponding to each L2 PDU set in the transmission frame 30 to the assembling unit 23.

  The assembly unit 23 can identify the L3 PDU to which each L2 PDU belongs because the L2 PDU and the L3SN corresponding to the L2 PDU are input from the transmission frame decomposition unit 22. The assembling unit 23 checks whether all the L2 PDUs necessary for reassembling each L3 PDU are available. The assembling unit 23 confirms whether or not all L2PDUs necessary for reassembling the L3PDU of “L3SN = N” and the L3PDU of “L3SN = N−1” are prepared.

  The assembly unit 23 reassembles the L3 PDU to be assembled regardless of whether or not the reassembly of the L3 PDU transmitted from the layer 3 transmission unit 3 before the L3 PDU to be assembled has been completed. When the L2 PDUs necessary for the preparation are complete, the L3 PDUs to be assembled are reassembled.

  Since the information indicating the end of the L3 PDU (L3SN = N) is set in the L2 PDU of “L2SN = n + 2”, the assembling unit 23 has all the L2 PDUs necessary for reassembling this L3 PDU. to decide. As a result, the assembling unit 23 reassembles the L3SN = N L3 PDUs regardless of whether all the L2PDUs necessary for reassembling the L3SN = N−1 L3 PDUs are prepared (step S130). The assembling unit 23 transmits the assembled L3 PDU to the layer 3 receiving unit 4 (upper layer) (step S140).

  As described above, according to the first embodiment, when a plurality of L2 PDUs (segments) obtained by dividing L3 PDUs (parent packets) are transmitted from the data transmission device 1 to the data reception device 2, a common L3SN is transmitted. Are combined into one to generate the transmission frame 30, so that it is possible to avoid overlapping setting of L3SN (parent packet sequence number) set in each segment. Accordingly, overhead for transmitting L3SN (information for identifying a parent packet) can be reduced, and data transmission can be performed efficiently.

  Since the transmission frame 30 is generated by adding information indicating the end of the L3 PDU to the L2 PDU corresponding to the end of the L3 PDU, the transmission is performed from the layer 3 transmission unit 3 before the L3 PDU to be assembled. Regardless of whether or not the reassembly of the L3 PDU that has been completed has been completed, the L3 PDU that is the assembly target can be assembled when the L2 PDUs necessary to reassemble the L3 PDU that is the assembly target are ready. It becomes possible. Therefore, L3 PDU can be quickly transmitted to the layer 3 receiving unit 4.

  In addition, among L3SNs of L3PDUs corresponding to L2PDUs, when the L3SNs are common, the common L3SNs are grouped together and arranged at the head of the L2PDU group, so that the data receiving apparatus can easily associate the L3SNs with the L2PDUs. Therefore, the L3 PDU can be easily assembled.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The data transmission system of the second embodiment has a configuration similar to that of the data transmission system 100 described with reference to FIG. 1 of the first embodiment, and performs the same operation as that of the data transmission system 100. The difference between the data transmission system 100 of the second embodiment and the data transmission system of the first embodiment is the frame format of the transmission frame 30 transmitted and received in the data transmission system 100.

  FIG. 7 is a diagram illustrating an example of a configuration of a transmission frame created by the data transmission apparatus according to the second embodiment. In the transmission frame 30 here, information on the L3 PDU (the number of L3SNs and L2 PDUs) is added together at the beginning of the transmission frame 30. That is, a plurality of types of L3SNs and information on the number of L2 PDUs corresponding to the L3SNs are stored at the beginning of the transmission frame 30.

  In the example of the transmission frame 30 illustrated in FIG. 7, four L2 PDUs of “L3SN = N−1” L2 PDU (L2SN = n−1) and “L3SN = N” (L2SN = n, n + 1, n + 2). Is shown packed in the transmission frame 30. Information on L3 PDUs corresponding to these four L2 PDUs is added to the head of the transmission frame 30 here. Specifically, as L3 PDU information, “L3SN = N−1”, information indicating that there is one L2PDU corresponding to this “L3SN = N−1”, “L3SN = N”, this “L3SN = Information indicating that there are three L2 PDUs corresponding to “N” is added to the head of the transmission frame 30.

  Then, after this head data (identification information storage area), information on each L2 PDU is arranged. That is, the transmission frame generation unit 14 arranges each data of L2 PDU (L2SN = n−1), L2 PDU (L2SN = n), L2 PDU (L2SN = n + 1), and L2 PDU (L2SN = n + 2) after the head data. A transmission frame 30 is generated. The transmission frame 30 generated by the transmission frame generation unit 14 is transmitted to the data reception device 2 via the physical layer control unit 5.

  Next, an operation procedure of the data receiving device 2 will be described. FIG. 8 is an explanatory diagram for explaining an operation procedure of the data receiving apparatus according to the second embodiment. In the data receiving apparatus 2 according to the second embodiment, the transmission frame decomposition unit 22 analyzes the transmission frame 30 illustrated in FIG. 7 and extracts L2 PDUs from the transmission frame 30. That is, the transmission frame decomposition unit 22 decomposes the transmission frame 30 from the error determination unit 21 and extracts the packed L2 PDU and the L3SN of the L3 PDU corresponding to this L2 PDU. Then, the transmission frame decomposing unit 22 inputs the extracted L2 PDU and the L3SN corresponding to each L2 PDU set in the transmission frame 30 to the assembling unit 23.

  The assembling unit 23 assembles L3 PDUs using L3SN and L2 PDU, similarly to the assembling unit 23 of the first embodiment. Then, the assembling unit 23 transmits the assembled L3 PDU to the layer 3 receiving unit 4 (upper layer).

  As described above, according to the second embodiment, when transmitting a plurality of L2 PDUs (segments) obtained by dividing L3 PDUs (parent packets) from the data transmission device 1 to the data reception device 2, information on the L3 PDUs is transmitted. Since (the number of L3SNs and L2 PDUs) are collectively added to the transmission frame 30, the overhead for transmitting L3SN (information identifying the parent packet) can be reduced as compared with the data transmission system 100 of the first embodiment. . Therefore, it is possible to perform data transmission more efficiently than data transmission system 100 of the first embodiment.

  In addition, since information on the number of L2 PNs corresponding to a plurality of types and the number of L2 PDUs corresponding to the L3SN is arranged at the beginning of the transmission frame 30, the data receiving apparatus can easily detect the association between the L3SN and the L2 PDU, L3 PDU can be easily assembled.

  As described above, the data transmission system, the data transmitting apparatus, and the data receiving apparatus according to the present invention are suitable for data transmission of layer 2 packets generated by dividing layer 3 packets.

It is a block diagram which shows the structure of the data transmission system which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement procedure of a data transmitter. It is explanatory drawing for demonstrating the operation | movement procedure of a data transmitter. 6 is a diagram illustrating an example of a configuration of a transmission frame created by the data transmission apparatus according to Embodiment 1. FIG. It is a flowchart which shows the operation | movement procedure of a data receiver. It is explanatory drawing for demonstrating the operation | movement procedure of a data receiver. 6 is a diagram illustrating an example of a configuration of a transmission frame created by a data transmission apparatus according to Embodiment 2. FIG. FIG. 10 is an explanatory diagram for explaining an operation procedure of the data receiving apparatus according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Data transmission apparatus 2 Data reception apparatus 3 Layer 3 transmission part 4 Layer 3 reception part 5,6 Physical layer control part 7 Transmission path 10 Layer 2 transmission part 11 Dividing part 12 Buffer part 13 Scheduling part 14 Transmission frame generation part 15 Retransmission control Unit 20 layer 2 reception unit 21 error determination unit 22 transmission frame decomposition unit 23 assembly unit 30 transmission frame 100 data transmission system

Claims (6)

In a data transmission system in which a plurality of layer 2 packets generated by dividing a layer 3 packet are collectively stored in a transmission frame for transmitting a physical layer and data is transmitted.
The transmission frame has an identification information storage area for storing identification information of a layer 3 packet to which a layer 2 packet stored in the own frame belongs,
When the identification information is common among layer 2 packets stored in the transmission frame, the identification information storage area is associated with a plurality of layer 2 packets associated with one identification information. A data transmission system characterized by storing identification information together.   The data transmission system according to claim 1, wherein information indicating the end of the layer 3 packet is added to a layer 2 packet corresponding to the end of the layer 3 packet among the layer 2 packets. . The transmission frame has the identification information storage area for each layer 2 packet group having the same identification information,
The data transmission system according to claim 1 or 2, wherein the identification information storage area is arranged at the head of each layer 2 packet group.   The identification information storage area is arranged at the beginning of the transmission frame, and relates to the number of layer 2 packets stored in the transmission frame among the layer 2 packets corresponding to the identification information together with a plurality of types of identification information. The data transmission system according to claim 1 or 2, wherein information is stored. In a data transmitting apparatus that divides a layer 3 packet to generate a layer 2 packet, and stores a plurality of generated layer 2 packets in a transmission frame for transmitting the physical layer and transmits data,
A transmission frame generation unit that generates a transmission frame having an identification information storage area for storing identification information of a layer 3 packet to which a layer 2 packet to be stored in the transmission frame belongs when generating the transmission frame;
When the identification information is common among layer 2 packets stored in the transmission frame, the transmission frame generation unit collectively stores the common identification information in the identification information storage area. Data transmission device. In a data receiving apparatus for receiving a transmission frame for transmitting a physical layer, in which a plurality of layer 2 packets generated by dividing a layer 3 packet are collectively stored,
A layer 2 packet extraction unit for extracting the identification information and a layer 2 packet corresponding to the identification information from a transmission frame having an identification information storage area for storing identification information of the layer 3 packet to which the layer 2 packet belongs;
A layer 3 packet generator that generates the layer 3 packet by assembling the layer 2 packet extracted by the layer 2 packet extractor based on the identification information extracted by the layer 2 packet extractor;
With
2. A data receiving apparatus according to claim 1, wherein when the identification information is common among layer 2 packets stored in the transmission frame, the common identification information is collectively stored in the identification information storage area.

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