JP3923959B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND RECORDING MEDIUM CONTAINING PROGRAM - Google Patents

Description

  The present invention relates to a communication device and a communication method, and more particularly to a communication device and a communication method using a unique header.

  In general, when performing bi-directional video communication, H.264 is generally used. 263, MPG2, MPG4, etc. are used to transmit / receive encoded data obtained by compressing video (see, for example, Non-Patent Document 1). These encoded data are generally transmitted in one packet per 1 VOP (Video Object Plane) using the RTP protocol. In the general Internet, the encoded data transmitted for each VOP can be received by the receiving terminal for each VOP. Therefore, the receiving terminal can decode the encoded data by removing the RTP header for each packet and passing the encoded data to the decoder. Here, even if a bit error occurs during communication, the receiving terminal can detect the bit error using a checksum included in the UDP header that is a subset of the RTP header. For this reason, it is possible to hide the disordered image by performing the skip process only on the VOP of the error packet.

  On the other hand, when transmitting and receiving encoded data via a corporate network or the like, communication must be performed beyond a proxy for ensuring security (see, for example, Non-Patent Document 2). Since a proxy can pass only a specific protocol, a tunneling technique that wraps a protocol that is desired to pass by a protocol that can pass the proxy is required (see, for example, Non-Patent Document 3). In general, HTTP tunneling that wraps RTP with HTTP makes it possible to pass through a proxy.

  The proxy has a cache function for temporarily storing packets transmitted from outside to inside such as a corporate network. A new packet including a plurality of VOPs is generated from the accumulated packets. For example, when two packets are accumulated as shown in FIG. 10A, the two data 1 and 2 from which the TCP header of each packet is removed are combined as shown in FIG. 10B. Data 1 'is added, and a new packet is generated by adding a TCP header to the data 1'. Therefore, in communication from outside to inside such as a corporate network, a new packet including a plurality of VOPs generated by the proxy is transmitted to the receiving terminal. Conventionally, a checksum included in a TCP header added only to a new packet is used to detect a bit error that occurs in communication between a proxy and a receiving terminal.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Ei Okubo / Masahisa Kawashima, “H.323 / MPEG4 Textbook”, IE Institute, 2001 Edited by Haruhisa Ishida, “Summary Check Internet Textbook (above)”, I & E Kamizo Laboratory, 2000 Shinichiro Fujiwara, “Basics for VoIP-Q & A for Communication Officers”, Rick Telecom, 2001

  However, in the conventional bit error detection method, even if a bit error is detected by a checksum included in the TCP header, it cannot be specified in which part of the new packet generated by the proxy the bit error has occurred. Using the example described above, it is impossible to distinguish whether the bit error occurrence location is data 1 or data 2 only by the checksum of the TCP header added to data 1 ′. For this reason, it is determined that all VOPs included in the new packet have a bit error. Therefore, when skip processing is performed, decoding is not performed for all VOPs included in the packet, and there is a problem in that the video during that time remains stopped.

  The present invention has been made to solve such problems, and an object of the present invention is to enable bit error detection in units of VOPs even when a plurality of packets are combined by a proxy.

In order to achieve such an object, a communication apparatus according to the present invention includes a unique header generating unit that generates a unique header including error confirmation information, and a packet with a unique header added before data to a network. Corresponding to data, transmitting means that encapsulates and transmits with a protocol that the proxy that relays access passes, receiving means that receives a packet including data and a unique header, dividing means that divides the received packet for each data, and data And bit error detection means for detecting the presence or absence of a bit error in the data using the error confirmation information of the unique header.

  Here, the unique header includes an identifier indicating the head of the unique header and a checksum of data as error confirmation information, and the dividing means starts from the position of the identifier of the unique header in the received packet. Unique header head position detection means for detecting the position, and when the received packet includes more than one set of unique headers and data, and there is a unique header after the data, the detected data and the unique header are And a restoration processing means for restoring the unique header and data by dividing at the head position of the unique header, and the bit error detecting means compares the data contents with the checksum of the unique header corresponding to the data to generate a bit. You may detect the presence or absence of an error.

Further, the communication device described above may further include a retransmission request unit that requests retransmission of the data and the corresponding unique header to the data transmission source when it is detected that the data has a bit error. Good.
In addition, using the video acquisition means that acquires the video and the video encoding method including the key frame compressed in the frame, the encoded data is generated in units of frames from the video and is output as data to the unique header generation means and the transmission means And an encoding processing means.

The retransmission request means is means for determining whether the data detected to have a bit error is a key frame, means for requesting retransmission when it is determined to be a key frame, and not a key frame. And a means for discarding the data when it is determined .

Also, the communication method according to the present invention includes a step of generating a unique header including error confirmation information in the transmitting client, and a proxy relaying access to the network through the packet with the unique header added before the data. Encapsulating with a protocol to be transmitted and transmitting from the sending client to the server; receiving a packet at the server; sending a packet received at the server to at least one receiving client; and at the receiving client The step of receiving the packet, the step of dividing the packet received by the receiving client for each data, and the receiving client detecting the presence / absence of a bit error in the data using the error check information of the unique header corresponding to the data Characterized in that it comprises the steps that.

The recording medium according to the present invention allows a unique header generating means for generating a unique header including error confirmation information, and a proxy for relaying access to the network to pass the packet with the unique header added before the data . Transmitting means for encapsulating and transmitting with a protocol, receiving means for receiving a packet including data and a unique header, dividing means for dividing the received packet for each data, and error confirmation information for the unique header corresponding to the data Is a recording medium on which is recorded a program for causing a computer to implement bit error detection means for detecting the presence or absence of a bit error in data.

  Here, the unique header includes an identifier representing the head of the unique header and a checksum of data as error confirmation information, is included in the dividing means, and is received from the position of the unique header identifier in the received packet. Means for detecting the head position of the data, and if the received packet contains more than one set of unique headers and data, and the unique header is present after the data because the received packet contains more than one set of unique headers and data. By dividing the header at the head position of the unique header and restoring the unique header and data, and by comparing the contents of the data with the checksum of the unique header corresponding to the data included in the bit error detection means A recording medium storing a program for causing a computer to further detect a bit error It may be.

In the present invention, a packet with a unique header added in front of data is encapsulated and transmitted by a protocol that allows a proxy that relays access to the network to pass through. Therefore, even if a plurality of packets are combined by a proxy or the like, a new packet is created. Even when generated, the original header and data before the combination can be restored by dividing based on the original header. Furthermore, bit errors can be detected in units of data by detecting bit errors using the error confirmation information in the unique header corresponding to each data. When this data corresponds to a VOP, it is possible to detect a bit error in units of VOP. Therefore, even if a bit error occurs in a new packet, a location where there is a bit error can be identified from among a plurality of packets constituting the new packet, so that a location where there is no bit error can be used.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a network configuration for explaining an embodiment of the present invention. In FIG. 1, a server 2 and a plurality of clients (communication devices) 3A, 3B, 3C (clients 3A to 3C may be collectively referred to as clients 3) are connected via an IP network 1 such as the Internet. Is done. However, the client 3C belongs to a corporate network or the like, and the corporate network or the like has a proxy 4 that relays access to the external IP network 1 from the inside. The proxy 4 is set so that only a specific protocol such as HTTP can pass through in order to ensure the security of the corporate network or the like.

  FIG. 2 is a block diagram showing the configuration of the client 3. The client 3 shown in this figure includes a camera 31, an encoding processing unit 32, a unique header generation unit 33, a transmission unit 34, a reception unit 35, a unique header head position detection unit 36, and a restoration processing unit 37. A bit error detection unit 38, a decoding processing unit 39, a display 40, a key frame determination unit 41, and a retransmission request generation unit 42. Hereinafter, each part 31-42 is demonstrated.

The camera (video acquisition unit) 31 is, for example, a USB connection camera or an NTSC TV camera connected via a capture board. The video (referred to as camera video) acquired by the camera 31 is output to the encoding processing unit 32.
The encoding processing unit 32 performs encoding processing of the camera video, and generates encoded data from the camera video in units of frames. For the encoding process, a video compression format for generating an intra-frame compressed key frame and an inter-frame compressed interpolated frame is used. For example, MPEG4 and H.264. H.263 (see Non-Patent Document 1, for example). Note that the video compression format used in the encoding process may be any format that can generate at least a key frame. The encoded data is output to the unique header generation unit 33 and the transmission unit 34.

  The unique header generation unit 33 generates a unique header added to the encoded data in units of frames. As shown in FIG. 3A, the unique header includes at least an encoded data checksum (information for error confirmation) and an identifier composed of a unique bit string (for example, a 64-bit string) representing the head of the unique header. included. The unique header is output to the transmission unit 34.

The transmission unit 34 transmits to the server 2 a packet in which a unique header corresponding to the encoded data is added before the encoded data in frame units. Here, the protocol to be passed by the proxy 4 is encapsulated. For example, a unique header is added in front of code data added to an RTP header, and these are regarded as one binary data and encapsulated with HTTP, which is a protocol that can pass through a proxy, and then transmitted by TCP. As shown in FIGS. 3B and 3C, a TCP packet in which a TCP header, an HTTP header, a unique header, an RTP header, and encoded data are arranged in this order is generated. The transmission unit 34 also transmits to the server 2 the encoded data generated by the retransmission request generation unit 42 to be described later and the retransmission request for the unique head.

  The receiving unit 35 receives a packet transmitted from the server 2 directly or via the proxy 4. As will be described later, since the server 2 transmits the packet transmitted from the transmission client to the reception client as it is, the reception packet directly received from the server 2 by the client 3 has the same data structure as the transmission packet shown in FIG. . On the other hand, the proxy 4 generates a new packet from a plurality of packets accumulated by the cache function. For example, as shown in FIG. 4A, the data 1 and 2 of two transmission packets are combined to generate a packet having a data structure as shown in FIG. As shown in FIG. 5, the encoded data and the unique header corresponding thereto may be divided into separate packets. In any case, the received packet received by the client 3 from the server 2 via the proxy 4 includes more than one set of encoded data and unique header, so that the unique head that should originally exist at the beginning is encoded. May exist after the data. The received packet received by the receiving unit 35 is output to the unique header head position detecting unit 36 and the restoration processing unit 37.

  The unique header head position detector 36 searches the received packet for an identifier representing the head of the unique header, and detects the head position of the unique header from the position of this identifier. The detection result is output to the restoration processing unit 37.

  As a result of detecting the head position of the unique header in the received packet by the unique header head position detecting unit 36, the restoration processing unit 37 has a unique header after the encoded data as shown in FIG. 4B or FIG. In this case, it is determined that the received packet has been received via the proxy 4, and the encoded data and the unique header are divided at the head position of the unique header. In this way, the data structure composed of the encoded data and the corresponding unique header before being combined by the proxy 4 is restored. Further, the restored encoded data and the unique header are output to the bit error detection unit 38, the decoding processing unit 39, and the key frame determination unit 41. On the other hand, if there is no unique header after the encoded data, it is determined that the received packet is directly received without going through the proxy 4, and the encoded data and the unique header input from the receiving unit 35 are The bit error detection unit 38, the decoding processing unit 39, and the key frame determination unit 41 are output as they are.

  The bit error detection unit 38 detects the presence or absence of a bit error in the encoded data. Specifically, first, a checksum of encoded data is obtained. When the restoration processing unit 37 determines that the received packet passes through the proxy 4, the checksum of the encoded data is compared with the checksum of the corresponding unique header. If it is determined that the received packet does not pass through the proxy 4, the checksum of the encoded data is compared with the checksum of the corresponding TCP header. As a result, if the checksum of the encoded data matches the checksum of the header, it is determined that there is no bit error in the encoded data, and if it does not match, it is determined that there is a bit error. When it is determined that there is no bit error, that fact is output to the decryption processing unit 39, and when it is determined that there is a bit error, that fact is output to the key frame determination unit 41.

The decoding processing unit 39 decodes the encoded data determined by the bit error detecting unit 38 to have no bit error.
The display (display unit) 40 displays the camera video decoded by the decoding processing unit 39.

The key frame determination unit 41 determines whether the frame of the encoded data is a key frame for the encoded data determined to have a bit error by the bit error detection unit 38. If it is determined that the frame is a key frame, the fact is output to the reproduction request generator 42. If it is determined that the frame is not a key frame, the encoded data is discarded.
When the key frame determination unit 41 determines that the encoded data with a bit error is a key frame, the retransmission request generation unit 42 generates a retransmission request for the encoded data and the unique head corresponding thereto, The data is output to the transmission unit 34.

FIG. 6 is a block diagram showing the configuration of the server 2. The server 2 shown in this figure has a reception unit 21, a control unit 22, a buffer 23, and a transmission unit 24. Hereinafter, each part 21-24 is demonstrated.
The reception unit 21 receives a packet transmitted from the transmission client 3 (3A) and outputs the received packet to the control unit 22. The receiving unit 21 also receives a retransmission request for a key frame transmitted from the receiving client 3 (3B, 3C), and outputs the received retransmission request to the control unit 22.

The control unit 22 copies the encoded data and the unique header included in the packet received by the reception unit 21 according to the number of reception clients. Here, two sets of encoded data and unique headers are duplicated corresponding to the receiving client 3 (3B, 3C). Also, it is determined whether the encoded data is a key frame. If it is determined that the encoded data is a key frame, the copied encoded data and the unique header are stored in the buffer 23. At this time, the encoded data and the unique header stored in the buffer 23 are deleted. That is, the contents of the buffer 23 are updated every time a key frame is received. Further, the copied encoded data and the unique header are output to the transmission unit 24.
The control unit 22 also reads the encoded data and the unique header stored in the buffer 23 when a retransmission request for the key frame is received, and outputs the read encoded data and the unique header to the transmission unit 24. To do.

  Based on the input from the control unit 22, the transmission unit 24 transmits, to the reception client 3 (3 </ b> B, 3 </ b> C), a packet with a unique header added before the encoded data. Here too, as with the transmission unit 24 of the client 3 (3A), the protocol to be passed is encapsulated by the protocol that the proxy 4 passes. The encoded data and the unique header transmitted from the transmission client 3 (3A) are transmitted to the reception client 3 (3B, 3C) without waiting time.

  Next, the communication method according to the present embodiment will be described with reference to FIGS. 7 to 9, taking as an example the case where video is transmitted from the transmission client 3A to the reception clients 3B and 3C via the server 2. FIG. 7 is a flowchart showing the flow of the transmission operation of the transmission client 3A. FIG. 8 is a flowchart showing the operation flow of the server 2. FIG. 9 is a flowchart showing a flow of reception operations of the reception clients 3B and 3C.

First, the transmission client 3A acquires a camera video by the camera 31 (step S1 in FIG. 7). The camera video is encoded in the encoding processing unit 32 to generate encoded data in units of frames (step S2 in FIG. 7). In addition, the unique header generation unit 33 generates a unique header to be added to the encoded data (step S3 in FIG. 7). And the packet which added the original header corresponding to this in front of encoding data is transmitted to the server 2 from the transmission part 34 (step S4 of FIG. 7). At this time, an original header is added in front of the code data added to the RTP header so that the packet can pass through the proxy 4 , and these are encapsulated with HTTP, which is a protocol that can be passed through the proxy as one binary data. After that, send by TCP.

When the server 2 receives the packet transmitted from the transmission client 3A by the reception unit 21 (steps S11 and S12 (NO) in FIG. 8), the control unit 22 receives the encoded data and the unique header included in the packet in the reception client 3B. , 3C are duplicated correspondingly. At this time, if the encoded data is a key frame, the copied encoded data and the unique header are stored in the buffer 23 (step S13 in FIG. 8). Then, the packet with the unique header added before the encoded data is transmitted from the transmitting unit 24 to the receiving clients 3B and 3C without waiting time (step S14 in FIG. 8). At this time, as in step S4 of FIG. 7 , a unique header is added before the code data added to the RTP header, and these are regarded as one binary data and encapsulated by HTTP, which is a protocol that can pass through the proxy. After that, send by TCP.

Hereinafter, the transmission to the reception client 3B and the transmission to the reception client 3C will be described separately. First, transmission to the receiving client 3B will be described.
The reception client 3B receives the packet transmitted from the server 2 by the reception unit 35 (step S21 in FIG. 9). Since the proxy 4 does not exist between the server 2 and the reception client 3B, the packet received by the reception unit 35 has the same data structure as the transmission packet shown in FIG. Therefore, when the unique header head position detection unit 36 searches for the head position of the unique header in the received packet, the head of the unique header appears only at the head of the received packet excluding the TCP header (step S22 in FIG. 9 (YES)). .

  Therefore, the bit error detection unit 38 detects the presence or absence of a bit error using the encoded data and the TCP header included in the received packet received by the reception unit 35. Specifically, first, the checksum of the encoded data is obtained and compared with the checksum of the TCP header (step S23 in FIG. 9). As a result, if they match, it is determined that there is no bit error in the encoded data (step S24 (YES) in FIG. 9), and the decoding processor 39 decodes the encoded data (FIG. 9). Step S25), the decoded camera image is displayed on the display 40 (Step S26 in FIG. 9).

  On the other hand, if the bit error detection unit 38 compares the checksum of the encoded data with the checksum of the TCP header and the two do not match, it is determined that there is a bit error (step S24 in FIG. 9). NO)). In this case, the key frame determination unit 41 determines whether or not the frame of encoded data determined to have a bit error is a key frame. As a result, when it is determined that the frame is not a key frame (step S27 (NO) in FIG. 9), the encoded data is discarded (step S28 in FIG. 9). If it is determined that the frame is a key frame (step S27 in FIG. 9 (YES)), the retransmission request generation unit 42 generates the encoded data and a retransmission request for the unique head corresponding thereto, and transmits The data is transmitted from the unit 34 to the server 2 (step S29 in FIG. 9).

  When the server 2 receives the retransmission request transmitted from the reception client 3B by the reception unit 21 (steps S11 and S12 (YES) in FIG. 8), the control unit 22 encodes the key frames stored in the buffer 23. The data and the unique header are read and retransmitted to the receiving client 3B (step S15 in FIG. 8). Although the frame rate is reduced by such retransmission processing of the key frame, it is possible to transmit and receive video without causing image disturbance due to bit errors.

Next, transmission from the server 2 to the receiving client 3C will be described.
Since the proxy 4 exists between the server 2 and the receiving client 3 </ b> C, a new packet is generated by combining the data of a plurality of packets as shown in FIG. 4B or 5 by the proxy 4. The receiving client 3C receives this new packet at the receiving unit 35 (step S21 in FIG. 9). When the unique header start position detection unit 36 searches for the start position of the unique header in the received packet, the start of the unique header appears not only at the beginning of the received packet excluding the TCP header but also after the encoded data (step in FIG. 9). S22 (NO)).

  Therefore, the restoration processing unit 37 divides the encoded data included in the received packet and the unique header at the head position of the unique header. In this way, the data structure composed of the encoded data and the corresponding unique header before being combined by the proxy 4 is restored (step S30 in FIG. 9). Then, the bit error detection unit 38 detects the presence or absence of a bit error using the restored encoded data and unique data instead of the TCP header. Specifically, first, the checksum of the encoded data is obtained and compared with the checksum of the unique header (step S23 in FIG. 9). As a result, if they match, it is determined that there is no bit error in the encoded data (step S24 (YES) in FIG. 9), and if they do not match, it is determined that there is a bit error ( Step S24 in FIG. 9 (NO)).

  Thus, by detecting a bit error using the checksum of the unique header, it is possible to detect a bit error in frame units (VOP units). Therefore, even if a bit error occurs in a new packet generated by the proxy 4, a VOP having a bit error can be identified from among a plurality of VOPs constituting the new packet, so that a VOP without a bit error is decoded. Can be displayed on the display 40.

  Note that the decryption process (step S25 in FIG. 9), the video display process (step S26 in FIG. 9), the key frame determination process (step S27 in FIG. 9), and the data discard process (step S28 in FIG. 9) in the receiving client 3C. The retransmission process (step S29 in FIG. 9) is the same as the process in the reception client 3B described above except that the encoded data used in the process is the encoded data restored in step S30. Is omitted.

In the present embodiment, the client 3 or the server 2 can be realized by a computer. The computer includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a circuit for interfacing with a display, a keyboard, an external storage device, or the IP network 1. It may be of a known configuration.
The CPU executes processing according to a program stored in the ROM or RAM or a command input from the keyboard. The CPU can also write data to the external storage device and read data from the external storage device. Further, the CPU can acquire data from the IP network 1 and send data to the IP network 1.

  In such a computer, a program for realizing the communication apparatus and method of the present invention is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, or a memory card. When this recording medium is inserted into the external storage device, the program written in the recording medium is read and transferred to the computer. Then, the CPU writes the read program into the RAM or the like. Thereafter, based on data input from the IP network 1, an external storage device or an external input device such as a keyboard, the CPU implements the above-described functional unit and executes the above-described processing.

  The present invention can be used for, for example, IP bidirectional image communication using a communication path in which a proxy exists. Moreover, it can be used not only for image communication but also for voice communication and other data communication.

It is a block diagram which shows the network structure for describing one embodiment of this invention. It is a block diagram which shows the structure of a client. It is a figure which shows the structure of the transmission packet containing the original header produced | generated by a client and this. It is a figure for demonstrating the structure of the new packet produced | generated by a proxy. It is a figure for demonstrating the structure of the new packet produced | generated by a proxy. It is a block diagram which shows the structure of a server. It is a flowchart which shows the flow of transmission operation | movement of a transmission client. It is a flowchart which shows the flow of operation | movement of a server. It is a flowchart which shows the flow of reception operation | movement of a reception client. It is a figure for demonstrating the structure of the new packet produced | generated by a proxy.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... IP network, 2 ... Server, 3 ... Client, 4 ... Proxy, 21 ... Reception part, 22 ... Control part, 23 ... Buffer, 24 ... Transmission part, 31 ... Camera, 32 ... Encoding process part, 33 ... Original Header generation unit 34 ... Transmission unit 35 ... Reception unit 36 ... Unique header head position detection unit 37 ... Restore processing unit 38 ... Bit error detection unit 39 ... Decoding processing unit 40 ... Display 41 ... Key Frame determination unit, 42... Retransmission request generation unit.

Claims (8)

A unique header generation means for generating a unique header including error confirmation information;
A transmission means for encapsulating and transmitting the packet with the unique header added in front of the data with a protocol that is passed by a proxy that relays access to the network ;
Receiving means for receiving a packet including data and a unique header;
Dividing means for dividing the received packet into the data;
Bit error detection means for detecting presence / absence of a bit error in the data using the error confirmation information of the unique header corresponding to the data. The communication device according to claim 1.
The unique header includes an identifier representing the head of the unique header, and a checksum of the data as the error confirmation information,
The dividing means includes
Unique header start position detecting means for detecting the start position of the unique header from the position of the identifier of the unique header in the received packet;
When the received packet includes more than one set of the unique header and the data, and the unique header is present after the data, the detected data and the unique header are replaced with the head of the unique header. A restoration processing means for restoring the unique header and the data by dividing at a position;
The bit error detecting means detects the presence or absence of a bit error by comparing the content of the data with a checksum of a unique header corresponding to the data. The communication device according to claim 1 or 2,
A communication apparatus, further comprising: a retransmission request unit that requests the data transmission source to retransmit the data and the corresponding unique header when it is detected that the data has a bit error. The communication device according to claim 3.
Video acquisition means for acquiring video;
An encoding processing unit that generates encoded data in units of frames from the video using a video encoding method including an intra-frame compressed key frame, and outputs the encoded data to the unique header generation unit and the transmission unit as the data; A communication device further comprising: The communication device according to claim 4, wherein
The retransmission request means includes
Means for determining whether the data detected to have a bit error is the key frame;
Means for requesting retransmission when it is determined to be the key frame;
Means for discarding the data when it is determined not to be the key frame. In the sending client, generating a unique header including information for error confirmation;
Encapsulating the packet with the unique header in front of the data with a protocol that is passed by a proxy that relays access to the network, and sending the packet from the sending client to the server;
Receiving the packet at the server;
Transmitting the received packet to at least one receiving client at the server;
Receiving the packet at the receiving client;
Dividing the received packet into the data at the receiving client;
And a step of detecting the presence or absence of a bit error in the data using the error confirmation information of the unique header corresponding to the data in the receiving client. A unique header generation means for generating a unique header including error confirmation information;
A transmission means for encapsulating and transmitting the packet with the unique header added in front of the data with a protocol that is passed by a proxy that relays access to the network ;
Receiving means for receiving a packet including data and a unique header;
Dividing means for dividing the received packet into the data;
A recording medium recording a program for causing a computer to implement bit error detection means for detecting the presence or absence of a bit error in the data using the error confirmation information of the unique header corresponding to the data. In the recording medium which recorded the program of Claim 7 ,
The unique header includes an identifier representing the head of the unique header, and a checksum of the data as the error confirmation information,
Means for detecting the leading position of the unique header from the position of the identifier of the unique header in the received packet included in the dividing means;
The detected data and the unique header when the unique packet is included after the data because the received packet includes more than one set of the unique header and the data. And reconstructing the unique header and the data by dividing the unique header and the head position of the unique header;
Recorded in the bit error detecting means is a program for further causing the computer to realize means for detecting the presence or absence of a bit error by comparing the content of the data with a checksum of a unique header corresponding to the data. recoding media.

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