JP4529883B2 - Packet transmission equipment - Google Patents

Description

  The present invention relates to a packet transmission apparatus that receives a packet transmitted from a terminal and redundantly transmits data included in the packet and a packet transmission apparatus that restores an original packet from the redundantly transmitted redundant packet.

As a technique for recovering an IP packet lost on a transmission line using redundant data, for example, there is a redundant transmission method conventionally defined in RFC 2198 of RFC (Request For Comment) that defines specifications related to the Internet protocol. .
The conventional packet redundant transmission method defined in RFC2198 aims to quickly restore an IP packet that has been lost on a transmission line, and in one IP (Internet Protocol) packet, voice data to be originally transmitted. In addition to the frame, a copy of the frame of the audio data transmitted immediately before is added as redundant data. When the original audio data frame is lost on the IP packet receiving side, it is possible to suppress the deterioration of the audio quality by restoring the lost audio data frame using redundant data. Yes.

  In the payload format of this redundant transmission system, 4-byte header information is always added to redundant data. The header information of the redundant data includes the payload type of the redundant data, the length of the redundant data, and the time stamp offset. The time stamp offset includes the original voice data transmitted as the same IP packet. The difference information with the time stamp of the RTP (Real-time Transport Protocol) header is stored.

RFC2198 (http://www.ietf.org/rfc/rfc2198.txt)

  However, in the conventional packet redundant transmission system, different types of time stamps that are counted up independently of each other are given to a plurality of types of transmission data, and the plurality of types of transmission data are mixedly transmitted. There is no provision for the case. Therefore, for example, when two types of data, that is, voice data and control signal are mixed as IP packets and input to the packet transmission device as the plurality of types of transmission data, the conventional packet redundant transmission method is used as the packet transmission device. When applied to the above, only the difference information of the RTP header time stamp is transmitted as the header information of the redundant data. However, there is a problem in that the time stamps of all redundant data cannot be accurately restored based on the time stamp of the RTP header in the packet transmission apparatus on the receiving side.

  Also, for example, ITU-T recommendation G. 729-compliant 8 kbit / s CS-ACELP (Conjugate Structure and Algebraic Code Excited Linear Prediction) audio data and control transmitted by DTMF (Dual Tone Multi Frequency) out-band transmission system defined by RFC2833 When two types of transmission data of signals are mixed and input to the packet transmission device as IP packets, the time stamps of the RTP header given to the voice data and the control signal are not continuous. When trying to transmit time stamp information so that it can be accurately restored, there is a problem that it may be larger than the range secured as header information.

  In addition, the conventional packet redundant transmission method has a problem in that since 4 bytes of header information is always added to the redundant data, the overhead of the redundant data increases and the peak value of the transmission line load during redundant transmission increases. It was.

  The packet transmission apparatus according to the present invention is provided with different series of time stamps that are counted up independently of each other, and when the plurality of types of transmission data are mixedly input, for example, voice data and control signal Even when two types of data are mixedly input, it is possible to accurately restore the redundantly transmitted packet in the packet transmission apparatus on the receiving side, and further, by reducing the overhead of redundant data, It aims at suppressing the peak value of the transmission line load at the time of transmission.

  The packet transmission apparatus according to the present invention includes a packet receiving unit that receives a plurality of packets transmitted continuously, a data type determining unit that determines a data type of data included in the packet received by the packet receiving unit, Based on the determination result of the data type determining means, the redundant packet assembling means for assembling the redundant packet of the redundant data of the received packet in different packet formats corresponding to the data type, and the redundant packet assembling means A redundant packet storing means for storing redundant packets; a transmission path packet assembling means for assembling a transmission path packet of a packet received by the packet receiving means using the redundant packets stored in the redundant packet storing means; and the transmission path The transmission path packet assembled by the packet assembly means It is obtained so as to include a transmission path packet transmitting means for transmitting to the sending passage.

  According to the present invention, by assembling redundant packets of redundant data in different packet formats corresponding to the data types of the data included in the received packet, the data type is determined from the packet format of the redundant packet on the redundant packet receiving side. In addition, the redundant packet can be formed with only necessary information corresponding to the data type, so that the redundantly transmitted packet can be accurately restored, the overhead of redundant data can be suppressed, and the transmission line load during redundant transmission can be reduced. The effect that the peak value can be suppressed is obtained.

Embodiments for carrying out the present invention will be described below.
Embodiment 1 FIG.
1 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 1 of the present invention. In this figure, reference numeral 101 denotes a packet receiving means for receiving a plurality of packets transmitted continuously. Here, an IP packet receiving unit for receiving an IP packet transmitted from a VoIP (Voice over Internet Protocol) terminal. is there. Reference numeral 102 denotes data type determination means for determining the data type of data included in the packet received by the packet reception means. Here, the type of data included in the IP packet received by the IP packet reception unit 101 is determined. It is a data type determination unit. 103 is a redundant packet assembling unit that assembles redundant packets of redundant data of the received packet in different packet formats corresponding to the data type based on the determination result of the data type determining unit. This is a redundant packet assembling unit that assembles redundant packets of packet formats having different packet lengths, header information, and the like according to the determination result of the determination unit 102. Reference numeral 104 denotes redundant packet storage means for storing redundant packets assembled in the redundant packet assembly means, and here, a redundant packet storage buffer for temporarily storing redundant packets assembled by the redundant packet assembly unit 103. Reference numeral 105 denotes transmission path packet assembling means for assembling the transmission path packet of the packet received by the packet receiving means using the redundant packet stored in the redundant packet accumulating means. Here, input from the data type determination unit 102 This is a transmission path packet assembly unit that assembles a transmission path packet to be transmitted to the transmission path from the IP packet and the redundant packet stored in the redundant packet storage buffer 104. Reference numeral 106 denotes transmission path packet transmission means for transmitting the transmission path packet assembled by the transmission path packet assembly means to the transmission path, and sends the transmission path packet assembled by the transmission path packet assembly unit 105 to the destination packet transmission apparatus. A transmission path packet transmitter.

  Reference numeral 107 denotes a transmission path in which redundant packets are assembled in different packet formats corresponding to the data types from the redundant data of the packets transmitted to the destination terminal device, and assembled using the assembled redundant packets. It is a transmission path packet receiving means for receiving a packet. Here, it is a transmission path packet receiving section for receiving a transmission path packet transmitted from the destination packet transmission apparatus, and the transmission path packet corresponds to the data type. The transmission path packets having different packet formats corresponding to the packet length and header information are received. 108 divides the transmission path packet received by the transmission path packet receiving means into a packet to be transmitted to the destination terminal device and a redundant packet, determines a data type based on the packet format of the redundant packet, Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device based on the determination result. Here, the transmission path packet received by the transmission path packet receiving unit 107 is defined as an IP packet. It is a redundant packet replacement unit that divides the packet into redundant packets and restores the IP packet sent from the redundant packet to the VoIP terminal. Reference numeral 109 denotes terminal packet storage means for storing packets transmitted to the destination terminal device obtained by the redundant packet replacement means. Here, the IP packet obtained by dividing by the redundant packet replacement unit 108 and redundant It is an IP packet storage buffer that temporarily stores the IP packet restored by the packet replacement unit 108. Reference numeral 110 denotes packet transmission means for transmitting the packet stored in the terminal packet storage means to the destination terminal device. Here, the IP packet stored in the IP packet storage buffer 109 is taken out and the VoIP terminal is extracted. This is an IP packet transmission unit to be transmitted to the network.

  111 controls the transmission path packet assembling means to assemble the transmission path packet using the redundant packet consisting of the transmission delay information until the number of packets received by the packet receiving means reaches a predetermined number. This is a redundant packet control means. Here, the number of IP packets received by the IP packet receiving unit 101 is measured for each call, and until the predetermined number of IP packets of the same call are received, the transmission path packet assembling unit 105 On the other hand, it is a redundant packet control unit that controls to assemble a transmission path packet by using a redundant packet made up of transmission delay information as a redundant packet.

  In the packet transmission apparatus of this configuration, the IP packet transmitted from the VoIP terminal is received, the redundant packet is assembled, and further, the transmission path packet sent to the transmission path is assembled using the IP packet and the redundant packet, The packet transmitting apparatus for sending the transmission path packet to the transmission path includes the IP packet receiving unit 101, the data type determination unit 102, the redundant packet assembly unit 103, the redundant packet storage buffer 104, the transmission path packet assembly unit 105, and the transmission path packet. The transmission unit 106 and the redundant packet control unit 111 are formed.

Also, a transmission path packet transmitted from the destination packet transmission apparatus is received, the received transmission path packet is divided into an IP packet and a redundant packet, and the IP packet is restored using the redundant packet, and the above transmission is performed. A packet receiving apparatus that transmits an IP packet obtained by dividing or restoring from a redundant packet to a VoIP terminal on the receiving side includes a transmission line packet receiving unit 107, a redundant packet replacing unit 108, an IP packet accumulation buffer 109, and It is formed by the IP packet transmission unit 110.

  The packet transmission apparatus shown in FIG. 1 includes a packet transmission apparatus and a packet reception apparatus. When the packet transmission device transmits a packet from the VoIP terminal, the packet transmission device transmits and receives the packet between the VoIP terminal and a packet reception device provided in another packet transmission device, and the packet reception device includes the VoIP terminal. When a packet transmitted from another VoIP terminal is received, a packet transmission device provided in another packet transmission device that transmits the packet transmitted from the other VoIP terminal and a receiving VoIP terminal Send and receive packets between them.

Next, the operation will be described.
First, the operation when the packet transmission apparatus according to Embodiment 1 of the present invention receives an IP packet from the VoIP terminal when an IP packet is transmitted from the transmitting VoIP terminal will be described. In this case, first, in the packet transmission apparatus, the IP packet receiving unit 101 receives the IP packet from the VoIP terminal, and outputs it to the data type determining unit 102 and the redundant packet control unit 111. Then, the data type determination unit 102 checks the IP packet input from the IP packet reception unit 101 and determines the type of data included in the IP packet.

  FIG. 2 is an explanatory diagram showing a packet format of an IP packet that the IP packet receiving unit 101 receives from a VoIP terminal. FIG. 3 is an explanatory diagram showing the data format of the RTP header. FIG. 4 is an explanatory diagram showing an outline of each item of the RTP header.

  For example, ITU-T Recommendation G. 729-compliant 8 kbit / s CS-ACELP encoded audio data and DTMF signal transmitted by DTMF out-of-band transmission method defined by RFC2833 as IP / UDP / RTP packets In the case of mixed input to the device, the data type determination unit 102 includes the input IP packet from the value stored in the payload type (PT) field of the RTP header included in the input IP packet. The type of data to be determined is determined. Specifically, G.M. When audio data encoded by the 729 method is transmitted as an RTP packet, since “18” is stored in the PT field of the RTP header, if the PT value of the RTP header of the input IP packet is “18” It is determined that the data is audio data, otherwise it is a control signal (DTMF signal). Then, the data type determination unit 102 outputs the input IP packet determination result and the IP packet to the redundant packet assembly unit 103.

  Then, the redundant packet assembling unit 103 assembles a redundant packet from the received IP packet information based on the determination result input from the data type determining unit 102. Here, the format of the redundant packet assembled by the redundant packet assembling unit 103 corresponds to each data type. Of the information included in the IP packet received by the packet receiving unit 101, information that can be restored on the receiving side of the transmission path packet is not stored, and information that cannot be accurately restored is stored. . In this embodiment, for example, the header information of redundant packets is redundant header information that can be restored by the packet transmission apparatus on the receiving side from transmission path packets assembled with IP packets and redundant packets corresponding to each data type. Assume that header information that cannot be accurately restored is stored in the header information of the redundant packet, not the header information of the packet. For example, the packet length of the redundant packet is set to a different packet length for each data type.

  In this way, in correspondence with each data type, information that can be restored by the packet transmission device on the receiving side is not stored in the redundant packet, and header information that cannot be accurately restored is stored in the redundant packet, thereby transmitting the packet on the receiving side. In the apparatus, the original RTP packet can be accurately restored from the redundant packet, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed. Also, by setting the packet length of the redundant packet to a different packet length for each data type, the data type can be determined from the packet length of the redundant packet in the packet transmission device on the receiving side. Since it is not necessary to incorporate the indicated information into the header information or the like, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed.

  In this embodiment, audio data or redundant data of a control signal and transmission delay information are transmitted as redundant packets. The redundant packet of audio data has no header information and a packet length of 20 bytes. FIG. 5 is an explanatory diagram showing the packet format of the redundant packet of the control signal. As shown in FIG. 5, the header information of the redundant packet including the control signal is composed of m (marker) and TimeStamp (time stamp) fields, and stores the values of the m and TimeStamp fields of the RTP header shown in FIG. Is done. The packet length is 9 bytes. The transmission delay information is information indicating the transmission delay of redundant data, and how many packets the redundant data is added to the IP packet after transmission, that is, how many packets the redundant data is transmitted with a delay. It is shown. For example, when redundant data is transmitted after being added to the IP packet after one packet, the transmission delay information is “1”, and when redundant data is transmitted after being added to the IP packet after two packets, transmission delay information is used. Becomes “2”. Here, the packet length of the redundant packet of the transmission delay information is 1 byte.

  When the redundant packet assembly unit 103 creates a redundant packet, for example, if the determination result input from the data type determination unit 102 is voice data, the redundant packet assembly unit 103 is input from the data type determination unit 102. The RTP packet payload is taken out of the IP packet and assembled as a 20-byte redundant packet. This redundant packet is stored in the redundant packet storage buffer 104.

  If the determination result input from the data type determination unit 102 is a control signal, the redundant packet assembling unit 103 extracts the payload of the RTP packet from the IP packet input from the data type determination unit 102, and FIG. As shown, header information is stored to assemble a redundant packet. The assembled 9-byte redundant packet is stored in the redundant packet storage buffer 104.

  On the other hand, the redundant packet control unit 111 identifies a call to which the IP packet input from the IP packet receiving unit 101 corresponds, and updates a counter for measuring the number of received IP packets prepared for each call. Then, according to the number of IP packets received in the same call, a signal indicating which redundant data of voice data or redundant data of the control signal or transmission delay information is added is output. When the number of IP packets received for the same call is smaller than a predetermined number, a signal for controlling the transmission path packet assembly unit 105 to assemble the transmission path packet using a redundant packet of transmission delay information is output. When the number of IP packets received for the same call exceeds a predetermined number, a transmission path packet is assembled to the transmission path packet assembly unit 105 using redundant packets of redundant data of voice data or control signals. The signal to be controlled is output. Thereby, for example, the redundant packet of the transmission delay information can be transmitted until the redundant packet of the redundant data is transmitted, and the packet transmission apparatus on the receiving side acquires the transmission delay information. Since redundant data is received, the original RTP packet (IP packet) can be accurately restored from the redundant packet. Also, since there is a transmission delay in the transmission of redundant data, the peak value of the transmission line load during redundant transmission can be suppressed by transmitting redundant packets of transmission delay information during the transmission delay.

  Next, the transmission path packet assembly unit 105 assembles a transmission path packet by adding a redundant packet to the end of the IP packet input from the data type determination unit 102 according to the signal input from the redundant packet control unit 111. FIG. 6 shows a packet format of the transmission path packet. When a signal for adding a redundant packet of transmission delay information is input from the redundant packet control unit 111, the transmission path packet assembly unit 105 transmits 1 byte as a redundant packet at the end of the IP packet input from the data type determination unit 102. Add delay information and assemble transmission path packet. For example, when a redundant packet is added to an IP packet after one packet and transmitted, 1-byte transmission delay information indicating “1” is added to the end of the IP packet.

  In addition, when a signal for adding redundant packets of voice data or redundant data of control signals is input from the redundant packet control unit 111, the transmission path packet assembly unit 105 stores the redundant packets stored in the redundant packet accumulation buffer 104. Is added to the end of the IP packet input from the data type determination unit 102. For example, when a redundant packet is added to an IP packet after one packet and transmitted, the redundant packet of redundant data corresponding to the previous IP packet is taken out from the redundant packet storage buffer 104 and added to the end of the IP packet.

  Then, the transmission path packet assembly unit 105 outputs the created transmission path packet to the transmission path packet transmission unit 106, and the transmission path packet transmission unit 106 transmits the input transmission path packet to the destination packet transmission apparatus. .

  The above is the operation when the packet transmission apparatus receives an IP packet from the VoIP terminal. Next, the operation of the packet transmission apparatus when a transmission path packet is received from the counterpart packet transmission apparatus will be described. In this case, first, the packet transmission apparatus receives the transmission path packet transmitted from the counterpart packet transmission apparatus by the transmission path packet reception unit 107, and outputs the transmission path packet to the redundant packet replacement unit 108.

  Next, the redundant packet replacement unit 108 divides the transmission path packet into an IP packet and a redundant packet transmitted to the destination terminal device to obtain an IP packet, and the redundant packet packet obtained by the above division The data type is determined based on the format, and the original IP packet is restored from the redundant packet based on the determination result.

  First, the redundant packet replacement unit 108 checks the header information of the transmission path packet input from the transmission path packet reception unit 107, and calculates the data length of the IP packet and the redundant packet to be transmitted to the VoIP terminal. For example, a table is prepared so that the header length and payload length of an IP packet to be transmitted to the VoIP terminal can be uniquely determined from the value of the PT field in the RTP header of the transmission path packet. Then, the redundant packet replacement unit 108 stores the IP packet to be transmitted to the VoIP terminal in the IP packet accumulation buffer 109. Further, the redundant packet replacement unit 108 determines the contents of the redundant packet from the data length of the redundant packet.

  In the present embodiment, the redundant packet length of the redundant packet is set to 20 bytes, 9 bytes, and 1 byte according to the data types of the redundant data of the audio data, the redundant data of the control signal, and the transmission delay information, respectively. Therefore, when the packet length of the redundant packet is 1 byte, the redundant packet replacement unit 108 determines that the redundant packet is transmission delay information, and stores this transmission delay information.

  If the redundant packet is 20 bytes, the redundant packet replacement unit 108 determines that the redundant packet is redundant data of the voice data, and uses the header information of the transmission path packet and the transmission delay information already stored. The RTP header corresponding to the redundant data of the voice data is generated.

  For example, when “1” is stored as the transmission delay information, a value obtained by adding 1 to the SN field value of the RTP header of the transmission path packet is set as the SN field value of the RTP header shown in FIG. Further, the difference between the set SN value and the SN value of the RTP header included in the IP packet of the voice data transmitted to the VoIP terminal received in the past is obtained, and the difference of the TimeStamp of the RTP header is calculated from the obtained difference by the following equation: Calculated by

TimeStamp difference = SN value difference × packetization period [msec] × number of samples

  Next, a value obtained by adding the difference of the calculated TimeStamp and the TimeStamp value of the RTP header included in the IP packet of the voice data transmitted to the VoIP terminal received in the past is set as the TimeStamp value of the RTP header of the redundant packet. The values of the v, p, x, cc, and SSRC fields of the RTP header shown in FIG. 2 store the field values of the RTP header of the transmission path packet, and the m field value is sent to the VoIP terminal that has been received in the past. The value of the m field of the RTP header included in the IP packet of the voice data to be transmitted is stored, and the value corresponding to the voice data defined in advance is stored in the PT field, thereby completing the RTP header of the redundant packet. Then, after assembling an IP packet using voice data as a payload using the generated RTP header, the assembled IP packet is stored in the IP packet accumulation buffer 109.

  If the redundant packet is 9 bytes, it is determined that the redundant packet is a combination of the redundant header and the control signal, and the RTP header information corresponding to the control signal is obtained using the header information of the transmission path packet and the redundant header information. Generate.

  For example, when “1” is stored as the transmission delay information, a value obtained by adding 1 to the SN field value of the RTP header of the transmission path packet is set as the SN field value of the RTP header shown in FIG. Further, the m and TimeStamp field values of the RTP header shown in FIG. 2 store the m and TimeStamp field values of the redundant header shown in FIG. Stores the field value of the RTP header of the transmission path packet, and stores the value corresponding to the preset control signal in the PT field, thereby completing the RTP header of the redundant packet. Then, an IP packet using the control signal as a payload is assembled using the generated RTP header. Then, the redundant packet replacement unit 108 stores the assembled IP packet in the IP packet accumulation buffer 109.

  In this way, by restoring the header information that can be restored from the transmission path packet received by the packet transmission device on the receiving side corresponding to each data type, and obtaining the header information that cannot be restored accurately from the header information of the redundant packet In the packet transmission apparatus on the receiving side, the original RTP packet and IP packet can be accurately restored from the redundant packet. For example, by using values such as transmission delay information transmitted as a redundant packet of a transmission path packet, an RTP header of an IP packet, a packetization period [msec] predetermined between VoIP terminals, the number of samples, etc. Header information corresponding to redundant packet data can be restored from the transmission path packet received by the packet transmission apparatus.

  When the IP packet assembled from the redundant packet is stored in the IP packet storage buffer 109, the redundant packet replacement unit 108 checks the SN field included in the RTP header of the IP packet stored in the IP packet storage buffer 109. Thus, the assembled IP packet is stored in a place where the SN field value continues. At this time, if an IP packet having the same SN value is already stored, the assembled IP packet is discarded.

  Next, the IP packet transmission unit 110 extracts the IP packet stored in the IP packet storage buffer 109 and sends it to the VoIP terminal.

  As described above, according to the first embodiment of the present invention, by assembling redundant packets of redundant data in different packet formats corresponding to the data types of data included in the received packet, the receiving side of the redundant packet In addition to determining the data type from the packet format of the redundant packet, the redundant packet can be formed with only necessary information corresponding to the data type, so that the overhead of redundant data can be suppressed and the peak value of the transmission line load during redundant transmission The effect that it can suppress is acquired. For example, by assembling redundant packets with different packet formats for voice data and control signals contained in IP packets, the overhead of redundant data can be suppressed and the peak value of the transmission line load during redundant transmission can be suppressed. The effect is obtained.

In addition, the packet format of the redundant packet is configured such that, among the information included in the received packet, information that can be restored on the receiving side of the transmission path packet is not stored, and information that cannot be restored accurately is stored. Since it is possible to form a redundant packet with only the information necessary to accurately restore the packet, it is possible to accurately restore the packet in the packet transmission device on the receiving side, and it is possible to suppress the overhead of redundant data, and the transmission line load during redundant transmission The effect that the peak value of can be suppressed is obtained.
For example, the redundant packet assembling unit 103 transmits only the voice data as the redundant packet without adding header information to the voice data, and the redundant packet replacement unit 108 determines the type of the redundant packet from the data length of the redundant packet. By specifying the above, it is possible to reduce the peak value of the transmission line load while realizing redundant transmission when voice data and control signals coexist in a transmission line that has the largest overhead of redundant packets during redundant transmission of voice data. The effect is obtained. For example, when the conventional packet redundant transmission system defined in RFC2198 is applied to a packet transmission apparatus, 1-byte header information is added to voice data and 4-byte header information is added to voice data redundant packets. Therefore, the data length of the transmission path packet is the G. When voice data encoded by the 729 method is transmitted as an IP packet in a cycle of 20 msec, assuming that the IP / UDP / RTP header length is 40 bytes, 40 + 1 + 20 + 4 + 20 = 85 bytes. On the other hand, in the first embodiment of the present invention, header information is not added to the voice data redundant packet, so the data length of the transmission path packet is 40 + 20 + 20 = 80 bytes. Therefore, in the first embodiment of the present invention, the data length of the transmission path packet can be reduced by about 6%.

  In addition, since the redundant packets are configured to have different packet lengths corresponding to the data types, the data type can be determined from the packet length of the redundant packets in the packet transmission device on the receiving side. Since it is not necessary to incorporate information indicating the packet type of the packet into the header information or the like, the overhead of redundant data can be suppressed, and the peak value of the transmission path load during redundant transmission can be suppressed. .

  Also, it is transmission delay information indicating the transmission delay of redundant data, and the transmission delay of redundant data is reduced by assembling transmission path packets using redundant packets configured in a packet format having a packet length different from that of redundant data of redundant data. It is not necessary to send the transmission delay information shown as the redundant packet header information consisting of redundant data, and the receiving side can determine from the packet length that the packet is a redundant packet consisting of transmission delay information. There is no need to incorporate information indicating the packet type into the header information or the like. Therefore, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed.

  Further, until the number of packets received by the IP packet receiving unit reaches a predetermined number, redundant packets of redundant data are transmitted by controlling to assemble transmission path packets using redundant packets consisting of transmission delay information. Up to this point, the redundant packet of the transmission delay information can be transmitted, and the receiving side packet transmission apparatus receives the redundant data after acquiring the transmission delay information. (IP packet) can be accurately restored. Also, since there is a transmission delay in the transmission of redundant data, the peak value of the transmission path load during redundant transmission can be suppressed by transmitting redundant packets of transmission delay information during the transmission delay. Is obtained.

  In addition, the transmission path packet is divided into a packet (IP packet) to be transmitted to the destination terminal device and a redundant packet, and the data type is determined based on the packet format of the redundant packet. Based on the determination result By restoring a packet (IP packet) transmitted from the redundant packet to the original destination terminal device, it is possible to transmit redundant data with a redundant packet formed only with necessary information corresponding to the data type. The overhead of redundant data can be suppressed and the peak value of the transmission line load at the time of redundant transmission can be suppressed.

  In the first embodiment of the present invention, the redundant packet control unit 111 specifies a call corresponding to the IP packet input from the IP packet receiving unit 101, and measures the number of received IP packets prepared for each call. The redundant packet control unit 111 has an I / F with an external server that manages the call connection of the VoIP terminal, and the information on the association between the IP packet transmitted from the VoIP terminal and the call You may make it acquire from an external server. In addition, when information on start / stop of call connection of the VoIP terminal is acquired from an external server that manages call connection of the VoIP terminal, and the call connection start information is acquired, the number of received IP packets prepared for each call is obtained. You may make it reset the counter for measuring.

  In the first embodiment of the present invention, the redundant packet control unit 111 specifies a call corresponding to the IP packet input from the IP packet receiving unit 101, and measures the number of IP packet receptions prepared for each call. However, the counter may be reset when an IP packet of the same call is not received for a certain period of time.

  In the first embodiment of the present invention, the redundant packet control unit 111 specifies a call corresponding to the IP packet input from the IP packet receiving unit 101, and measures the number of received IP packets prepared for each call. However, it is also possible to check changes in the values of the SN and TimeStamp fields of the RTP header for each received IP packet, and reset the counter when packet continuity is lost. For example, if the VoIP terminal is G.264. When voice data encoded by the 729 method is transmitted as an IP packet in a cycle of 20 msec, normally, the SN of the RTP header increases by +1 and the TimeStamp increases by +160 for each IP packet. Therefore, when a certain number or more of IP packets whose TimeStamp change amount does not match the SN change amount compared to the IP packet received immediately before are received, it is determined that the continuity of the packet is lost. Good.

  In the first embodiment of the present invention, ITU-T Recommendation G. The data encoded by the 8kbit / s CS-ACELP system conforming to the G.729 standard is used as voice data. Data encoded by a method other than 729 may be used as audio data.

  In the first embodiment of the present invention, the DTMF signal transmitted by the DTMF out-of-band transmission system defined by RFC2833 is used as the control signal. For example, the teletype code information, the FAX signal or the modem signal is demodulated. Information other than the DTMF signal, such as a signal, may be used as the control signal.

Embodiment 2. FIG.
In Embodiment 1 described above, a case has been described in which transmission delay information, which is information indicating the transmission delay of redundant data, is transmitted as a redundant packet until the packet transmission apparatus receives a predetermined number of IP packets. In the second embodiment, a case where the call connection operation of the VoIP terminal is monitored and the transmission delay information is transmitted as a part of the information of the call connection operation will be described.

  FIG. 7 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 2 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, 201 is a packet receiving means for receiving a plurality of packets transmitted continuously, and here is an IP packet receiving section for receiving an IP packet transmitted from a VoIP terminal. 202 is a redundant packet assembling unit that assembles redundant packets of redundant data of the received packet in different packet formats corresponding to the data types. Here, the IP packet and the redundant packet input from the data type determination unit 102 This is a transmission path packet assembly unit that creates a transmission path packet (IP packet) to be sent to the transmission path from the redundant packet stored in the accumulation buffer 104. Reference numeral 203 denotes a transmission path packet transmission means for transmitting the assembled transmission path packet to the transmission path. Here, the transmission path packet (IP packet) created by the transmission path packet assembly unit 202 is sent to the destination packet transmission apparatus. A transmission path packet transmitter.

  In addition, reference numeral 204 denotes a transmission in which redundant packets are assembled in different packet formats corresponding to the data types from the redundant data of the packet data transmitted to the destination terminal device, and assembled using the assembled redundant packets. It is a transmission path packet receiving means for receiving a path packet, and here is a transmission path packet receiving section for receiving a transmission path packet transmitted from the packet transmission apparatus of the other party. 205 divides the transmission path packet received by the transmission path packet receiving means into a packet to be transmitted to the destination terminal device and a redundant packet, determines a data type based on the packet format of the redundant packet, Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device based on the determination result. Here, the transmission path packet received by the transmission path packet receiving unit 204 is defined as an IP packet. This is a redundant packet replacement unit that divides the packet into redundant packets and assembles an IP packet to be sent to the VoIP terminal using the transmission delay information received from the communication partner packet transmission apparatus. Reference numeral 206 denotes terminal packet storage means for storing packets transmitted to the destination terminal device obtained by the redundant packet replacement means. Here, the IP packet stored in the IP packet storage buffer 109 is taken out and VoIP is extracted. It is an IP packet transmission unit that transmits to a terminal.

  207 is a connection control means for monitoring the call connection between the terminal devices and adding transmission delay information indicating the transmission delay of the redundant data to the packet for controlling the call connection between the terminal devices. A transmission path packet (IP packet) received by the transmission path packet receiving unit 204 is analyzed to acquire transmission delay information. Here, it is determined whether or not the received IP packet or transmission path packet includes call connection operation information, and by detecting the connection operation, the call connection operation between VoIP terminals is monitored, and a new call is received. This is a connection control unit for exchanging transmission delay information with a counterpart packet transmission apparatus when transmitting a redundant packet of voice data transmitted from a connected VoIP terminal.

Next, the operation will be described.
There are three states of call connection between VoIP terminals monitored by the connection control unit 207: call connection not detected, call connection start, and call connection start completion. The connection control unit 207 detects the start of the call connection when the call connection is not detected, and detects the completion of the start of the call connection when the call connection is started. Then, the connection control unit 207 adds the transmission delay information indicating the transmission delay of the redundant data to the packet for controlling the call connection between the terminal apparatuses until the start completion is detected after the call connection is started. On the receiving side, the transmission delay information is acquired from the start of call connection until the start completion is detected. Hereinafter, the operation of each state of call connection will be described.

  First, the operation of the packet transmission apparatus when the connection control unit 207 has not detected the call connection operation of the VoIP terminal will be described. First, the operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, first, the packet transmission apparatus receives an IP packet from the VoIP terminal by the IP packet receiving unit 201 and outputs the received IP packet to the connection control unit 207.

  Next, the connection control unit 207 analyzes the IP packet input from the IP packet receiving unit 201 and determines whether the IP packet is call connection operation information. When the IP packet is not call connection operation information, the input IP packet is output to the IP packet receiving unit 201. On the other hand, when the IP packet is call connection operation information, the call connection operation information included in the IP packet input from the IP packet receiving unit 201 is analyzed to detect the start of the call connection operation of the VoIP terminal. . Further, after specifying the packet transmission device corresponding to the partner VoIP terminal from the call connection operation information included in the IP packet, and setting the destination of the IP packet including the call connection operation information to the specified packet transmission device And output to the transmission path packet transmission unit 203. Then, the transmission path packet transmission unit 203 outputs the IP packet input from the connection control unit 207 to the counterpart packet transmission apparatus.

  Next, an operation when a transmission path packet (IP packet) is received from the counterpart packet transmission apparatus in a state where the connection control unit 207 has not detected the call connection operation of the VoIP terminal will be described. In this case, the packet transmission apparatus first outputs the transmission path packet (IP packet) received from the destination packet transmission apparatus by the transmission path packet reception unit 204 to the connection control unit 207. The connection control unit 207 analyzes the transmission path packet (IP packet) input from the transmission path packet reception unit 204 and determines whether the transmission path packet (IP packet) is call connection operation information. If the transmission path packet is not call connection operation information, the input transmission path packet (IP packet) is output to the transmission path packet reception unit 204. On the other hand, when the IP packet is call connection operation information, the connection control unit 207 analyzes the call connection operation information included in the transmission path packet (IP packet) received from the transmission path packet reception unit 204, and The partner VoIP terminal to which the call connection operation information is transmitted is specified, and a transmission path packet (IP packet) including the call connection operation information is output to the IP packet transmission unit 206. Then, the IP packet transmission unit 206 transmits the transmission path packet (IP packet) input from the connection control unit 207 to the VoIP terminal.

  The above is the operation of the packet transmission apparatus when the connection control unit 207 has not detected the call connection operation of the VoIP terminal. Next, the operation of the packet transmission apparatus when the connection control unit 207 detects the start of call connection of the VoIP terminal will be described. First, the operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, the packet transmission apparatus receives the IP packet from the VoIP terminal by the IP packet receiving unit 201, and outputs the received IP packet to the connection control unit 207. Next, the connection control unit 207 determines whether or not the IP packet input from the IP packet receiving unit 201 is call connection operation information. When the IP packet is not call connection operation information, the input IP packet is output to the IP packet receiving unit 201. On the other hand, when it is determined that the IP packet input from the IP packet receiving unit 201 is call connection operation information, the connection control unit 207 adds redundant data transmission delay information to the call connection operation information, as shown in FIG. After that, the assembled IP packet is output to the transmission path packet transmission unit 203. FIG. 8 is an explanatory diagram showing an IP packet in which redundant data transmission delay information is added to call connection operation information. Further, the connection control unit 207 analyzes the call connection operation information included in the output IP packet, and detects the completion of the start of the call connection. Then, the transmission path packet transmission unit 203 outputs the IP packet including the call connection operation and the redundant data transmission delay information input from the connection control unit 207 to the destination packet transmission apparatus.

  Next, an operation when the connection control unit 207 receives an IP packet from the counterpart packet transmission apparatus in a state where the start of the call connection of the VoIP terminal is detected will be described. In this case, the packet transmission apparatus outputs the transmission path packet (IP packet) received from the destination packet transmission apparatus by the transmission path packet reception unit 204 to the connection control unit 207. The connection control unit 207 analyzes the transmission path packet (IP packet) input from the transmission path packet reception unit 204 and determines whether the transmission path packet (IP packet) is call connection operation information. If the transmission path packet (IP packet) is not call connection operation information, the input transmission path packet (IP packet) is output to the transmission path packet receiving unit 204. On the other hand, when the transmission path packet (IP packet) is information on the call connection operation, the connection control unit 207 analyzes the transmission path packet (IP packet) received from the transmission path packet reception unit 204 and determines the redundant data. Get transmission delay information. Then, the connection control unit 207 outputs the acquired transmission delay information to the redundant packet replacement unit 205. Further, the VoIP terminal that is the other party of the call connection is specified from the call connection operation information included in the transmission path packet (IP packet), and the transmission delay information is deleted from the transmission path packet (IP packet) to transmit the IP packet. To the unit 206. Then, the IP packet transmission unit 206 transmits the transmission path packet (IP packet) input from the connection control unit 207 to the VoIP terminal.

The above is the operation of the packet transmission apparatus in a state where the connection control unit 207 detects the start of the call connection of the VoIP terminal. Next, the operation of the packet transmission apparatus in a state where the connection control unit 207 detects the completion of the call connection of the VoIP terminal will be described.
First, an operation when the packet transmission apparatus receives an IP packet of voice data from a VoIP terminal will be described. In this case, the packet transmission apparatus receives the IP packet from the VoIP terminal by the IP packet receiving unit 201, and outputs the received IP packet to the connection control unit 207.

  Next, the connection control unit 207 analyzes the IP packet input from the IP packet receiving unit 201 and determines whether the IP packet is call connection operation information. Here, since the IP packet of the voice data is received, it is determined that the IP packet is not call connection operation information, and the input IP packet is output to the IP packet receiving unit 201. Then, the IP packet reception unit 201 outputs the input IP packet to the data type determination unit 102. The subsequent operations of the data type determination unit 102, the redundant packet assembly unit 103, and the redundant packet storage buffer 104 are the same as those in the first embodiment, and thus description thereof is omitted.

Next, the transmission path packet assembly unit 202 takes out the redundant packet stored in the redundant packet accumulation buffer 104 and adds it to the end of the IP packet input from the data type determination unit 102. For example, when a redundant packet is added to the IP packet after one packet and transmitted, the redundant packet corresponding to the previous IP packet is extracted from the redundant packet storage buffer 104 and added to the end of the IP packet.
Then, the transmission path packet assembly unit 202 outputs the created transmission path packet to the transmission path packet transmission unit 203, and the transmission path packet transmission unit 203 transmits the input transmission path packet to the destination packet transmission apparatus. .

  Next, an operation when the connection control unit 207 receives a transmission line packet from the counterpart packet transmission apparatus in a state where the start of call connection of the VoIP terminal is detected will be described. In this case, the packet transmission apparatus first receives the transmission path packet (IP packet) transmitted from the destination packet transmission apparatus by the transmission path packet receiving unit 204. The transmission path packet receiving unit 204 outputs the received transmission path packet (IP packet) to the connection control unit 207. The connection control unit 207 analyzes the transmission path packet (IP packet) input from the transmission path packet reception unit 204 and determines whether the transmission path packet (IP packet) is call connection operation information. Here, since it is not information of the call connection operation, the input transmission path packet (IP packet) is output to the transmission path packet receiving unit 204. The transmission path packet 204 outputs the input transmission path packet (IP packet) to the redundant packet replacement unit 205.

  Next, the redundant packet replacement unit 205 checks the header information of the transmission path packet (IP packet) input from the transmission path packet reception unit 204, and calculates the data length of the IP packet and redundant packet to be transmitted to the VoIP terminal. To do. For example, a table is prepared so that the header length and payload length of an IP packet to be transmitted to the VoIP terminal can be uniquely determined from the value of the PT field in the RTP header of the transmission path packet. Then, the redundant packet replacement unit 205 stores the IP packet to be transmitted to the VoIP terminal in the IP packet accumulation buffer 109. Further, the redundant packet replacement unit 205 determines the contents of the redundant packet from the data length of the redundant packet. For example, the type of data length transmitted by the packet transmission device as a redundant packet is set in advance as a fixed value, such as 20 bytes for voice data, 9 bytes for redundant headers and control signals, and the redundant packet is 20 bytes. In this case, it is determined that the redundant packet is voice data, and the RTP header corresponding to the voice data is generated using the header information of the transmission path packet and the transmission delay information that is already stored, and the voice data is transferred to the payload. Are assembled and stored in the IP packet storage buffer 109. If the redundant packet is 9 bytes, it is determined that the redundant packet is a combination of the redundant header and the control signal, and the RTP header information corresponding to the control signal is obtained using the header information of the transmission path packet and the information of the redundant header. Generate and assemble an IP packet with the control signal as the payload. Then, the redundant packet replacement unit 205 stores the assembled IP packet in the IP packet accumulation buffer 109.

  Since the operation of the IP packet storage buffer 109 is the same as that of the first embodiment, the description thereof is omitted. Next, the IP packet transmission unit 206 extracts the IP packet stored in the IP packet accumulation buffer 109, and then transmits the IP packet to the VoIP terminal.

  As described above, according to the second embodiment of the present invention, the connection control unit 207 determines whether or not the input packet is call connection operation information, and detects the connection operation. By monitoring the call connection operation, and notifying the other party's packet transmission device of the transmission delay information indicating the transmission delay of the redundant data as part of the call connection operation information (packet for controlling the call connection), In the destination packet transmission apparatus, the RTP header corresponding to the redundant packet can be accurately restored. Further, since it is not necessary to send transmission delay information indicating the transmission delay of redundant data as header information of redundant packets made of redundant data, it is not necessary to incorporate information indicating the packet type of redundant packets into header information or the like. Since transmission delay information can be transmitted as a packet for controlling call connection, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed.

  Also, the connection control unit 207 monitors the call connection operation of the VoIP terminal, and transmits the transmission delay information indicating the transmission delay of redundant data as part of the call connection operation information (packet for controlling the call connection). By notifying the packet transmission apparatus, it is possible to always add voice data or a control signal as a redundant packet to the transmission path packet, and the effect of improving the packet loss tolerance on the transmission path can be obtained.

Embodiment 3 FIG.
In the second embodiment, the call connection operation information of the VoIP terminal is monitored, and the transmission destination information indicating the transmission delay of the redundant data is used as part of the call connection operation information (packet for controlling the call connection). In the third embodiment, the call connection operation of the VoIP terminal is monitored, and the voice data and the control signal are redundant only immediately after the new call connection is completed. A case where transmission delay information is transmitted as a redundant packet instead of a packet will be described.

  FIG. 9 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 3 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, 301 monitors the call connection between terminal devices, and transmits to the transmission line packet assembly unit 105 using the redundant packet made up of the transmission delay information only immediately after the start of call connection. This is a connection / redundant packet control means for controlling so as to assemble a route packet. Here, a call connection operation between VoIP terminals is detected, and the redundancy data is stored as a redundant packet only immediately after a new call connection is completed. It is a connection / redundant packet control unit that controls to output transmission delay information.

Next, the operation of the connection / redundant packet control unit 301 will be described.
First, regarding the operation in the state where the connection / redundant packet control unit 301 has not detected the call connection operation of the VoIP terminal, the connection control unit 207 shown in the second embodiment detects the call connection operation of the VoIP terminal. Since the operation is the same as that in the non-operating state, the description thereof is omitted.

  Next, an operation when an IP packet is input from the IP packet receiving unit 201 in a state where the connection / redundant packet control unit 301 detects the start of call connection of the VoIP terminal will be described. In this case, the connection / redundant packet control unit 301 first determines whether or not the IP packet input from the IP packet receiving unit 201 is call connection operation information. If it is determined that the IP packet input from the IP packet receiving unit 201 is call connection operation information, the connection / redundant packet control unit 301 transmits the packet transmission corresponding to the partner VoIP terminal from the call connection operation information. The device is specified, and the destination of the IP packet including the information of the call connection operation is set in the specified packet transmission device and output to the transmission path packet transmission unit 203. Further, the connection / redundant packet control unit 301 analyzes the call connection operation information and detects the completion of the call connection. When a call connection completion is detected, a new counter for storing the number of IP packet receptions corresponding to the call is prepared, and the counter is initialized.

  Then, after the connection / redundant packet control unit 301 detects the completion of the connection of the call of the VoIP terminal, the IP packet receiving unit 201 receives the IP packet and the prepared counter reaches once, that is, a new call is made. Only after the connection is completed, the connection / redundant packet control unit 301 controls the transmission path packet assembling unit 105 to assemble the transmission path packet using the redundant packet that is the transmission delay information.

  Note that regarding the operation of the packet transmission apparatus in a state where the connection / redundant packet control unit 301 detects the completion of the connection of the call of the VoIP terminal, in the operation of the packet transmission apparatus described in Embodiment 1, the redundant packet control unit 111 Since the predetermined number when controlling the transmission path packet assembling unit 105 is 1 (the initial value of the counter + 1), the description is omitted.

The operation when the IP packet is input from the transmission path packet receiving unit 204 in the state where the connection / redundant packet control unit 301 detects the start of the call connection of the VoIP terminal is the connection shown in the second embodiment. Since the operation is the same as the operation when the control unit 207 detects the start of the call connection of the VoIP terminal, the description is omitted.
Further, the operation of the packet transmission apparatus in a state where the connection / redundant packet control unit 301 detects the completion of the call connection of the VoIP terminal is the same as the operation of the packet transmission apparatus described in the first embodiment. Omitted.

  As described above, according to the third embodiment of the present invention, the connection / redundant packet control unit 301 determines whether or not the input packet is call connection operation information, and detects the connection operation. The call connection operation of the VoIP terminal is monitored, and as soon as the call connection is completed, a transmission path packet is assembled using redundant packets consisting of transmission delay information of redundant data instead of redundant packets of voice data and control signals. Thus, the RTP header corresponding to the redundant packet can be accurately restored in the counterpart packet transmission apparatus. In addition, since it is not necessary to send transmission delay information indicating the transmission delay of redundant data as header information of redundant packets made of redundant data, it is not necessary to incorporate information indicating the packet type of redundant packets into header information etc. Since transmission delay information can be transmitted as a redundant packet of the first IP packet for which there is no redundant data to be transmitted as a redundant packet, the overhead of redundant data can be suppressed and the peak value of the transmission line load during redundant transmission can be suppressed. The effect that it can be obtained.

  In addition, the connection / redundant packet control unit 301 monitors the call connection operation of the VoIP terminal, and only after the call connection is completed, the transmission delay information of the redundant data is used instead of the redundant packet of the voice data or the control signal. The transmission delay of redundant data as a redundant packet can be controlled only when the first IP packet that does not have redundant data to be transmitted as a redundant packet is transmitted by controlling to assemble and transmit the transmission path packet using the redundant packet. Since it is possible to transmit information, if there is voice data or control signal that can be transmitted as a redundant packet, it can always be added as a redundant packet to the transmission path packet, and the packet loss tolerance in the transmission path The effect of improving is obtained.

Embodiment 4 FIG.
In the third embodiment, a case has been described in which transmission delay information of redundant data is transmitted as a redundant packet instead of voice data or a control signal only immediately after the call connection is completed. A case will be described in which the presence / absence of voice data input from a terminal is detected and transmission delay information of redundant data is transmitted instead of redundant packets of silent voice data.

  FIG. 10 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 4 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, 401 is a silence detection unit that determines whether or not the voice data of the IP packet transmitted from the VoIP terminal is silent. Reference numeral 402 denotes a transmission path packet assembling means for assembling a transmission path packet using a redundant packet consisting of transmission delay information when the data included in the packet received by the packet receiving means is silent audio data. Redundant packet control means for controlling, in this case, when the data included in the IP packet received by the packet receiving unit 101 is silent audio data to the transmission path packet assembling unit 105, the silent audio data The transmission packet is controlled to be assembled using a redundant packet consisting of transmission delay information instead of the redundant packet of the IP packet, and the number of IP packets received by the IP packet receiving unit 101 is measured for each call. Until a predetermined number of IP packets of the call are received, transmission delay information is transmitted to the transmission path packet assembly unit 105. Even when a predetermined number of IP packets of the same call are received, control is performed to assemble transmission path packets using long packets. It is a redundant packet control unit that controls to assemble transmission path packets using redundant packets.

Next, the operation will be described.
First, the operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, first, the packet transmission apparatus receives the IP packet from the VoIP terminal by the IP packet receiving unit 101 and outputs it to the data type determination unit 102 and the redundant packet control unit 402. Then, the data type determination unit 102 determines the data type of the input IP packet, and outputs the input IP packet and the determination result of the IP packet to the redundant packet assembly unit 103. The operation of determining the type of data included in the IP packet by the data type determination unit 102 is the same as that in the first embodiment, and thus the description thereof is omitted. If the data type determination unit 102 determines that the data of the IP packet is not a control signal, the data type determination unit 102 regards the IP packet as voice data and outputs it to the silence detection unit 401. Note that the operations of the redundant packet assembling unit 103 and the redundant packet storage buffer 104 are the same as those in the first embodiment, and thus the description thereof is omitted.

  Next, the silence detector 401 determines whether or not the voice data included in the input IP packet is silent. For example, the signal level of the voice data included in the input IP packet is calculated, and if the signal level is equal to or higher than a preset threshold value, the voice data is determined to be sound. Then, the silence detection unit 401 outputs a signal indicating the presence / absence of voice data to the redundant packet control unit 402 according to the determination result.

  Then, the redundant packet control unit 402 identifies a call to which the IP packet input from the IP packet receiving unit 101 corresponds, and updates a counter for measuring the number of IP packet receptions prepared for each call. When the number of IP packets received for the same call is smaller than a predetermined number, a signal for adding transmission delay information as a redundant packet is output to the transmission path packet assembly unit 105. Further, when the number of IP packets received for the same call exceeds a predetermined value, an output signal is determined according to the signal input from the silence detection unit 401. For example, when a signal indicating the sound of voice data is received from the silence detection unit 401, a normal redundant packet is added in accordance with the timing at which the redundant packet corresponding to the signal indicating sound is added to the transmission path packet. The signal is output to the transmission path packet assembly unit 105. In addition, when a signal indicating silence in the audio data is received from the silence detection unit 401, transmission delay information is added as a redundant packet in accordance with the timing at which the redundant packet corresponding to the signal indicating silence is added to the transmission path packet. The signal is output to the transmission path packet assembly unit 105. The operations of the transmission path packet assembly unit 105 and the transmission path packet transmission unit 106 are the same as those in the first embodiment, and a description thereof will be omitted.

  The above is the operation when the packet transmission apparatus receives an IP packet from the VoIP terminal. The operation when a transmission path packet is received from the counterpart packet transmission apparatus is the same as that in the first embodiment, and thus the description thereof is omitted.

  As described above, according to the fourth embodiment of the present invention, the silence detecting unit 401 determines whether or not the voice data input from the VoIP terminal is silent, and the voice data is silent voice data. In addition, the redundant packet control unit 402 controls the transmission path packet assembling unit 105 to assemble the transmission path packet using the redundant packet including the transmission delay information instead of the redundant packet of the voice data determined to be silent. As a result, even when a burst loss occurs in the transmission path, transmission delay information can be transmitted to the destination packet transmission apparatus, and the destination packet transmission apparatus creates an IP packet from the redundant packet. In this case, there is an effect that the RTP header can be accurately restored.

Embodiment 5 FIG.
In the fifth embodiment, the redundant packet control shown in the first embodiment is applied to a packet transmission apparatus that multiplexes and transmits IP packets received from one or a plurality of VoIP terminals.

  FIG. 11 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 5 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, reference numeral 501 denotes short packet assembling means for assembling a short packet of a packet received by the packet receiving means using the redundant packet stored in the redundant packet accumulating means. This is a short packet assembly unit that creates a short packet from the IP packet received from the data type determination unit 102 and the redundant packet stored in the redundant packet storage buffer 104. Reference numeral 502 denotes short packet storage means for storing short packets assembled in the short packet assembly means. Here, the short packet storage buffer temporarily stores the short packets created by the short packet assembly unit 501. . Reference numeral 503 denotes multiplexed packet assembling / transmitting means for multiplexing the short packets stored in the short packet storing means and sending the multiplexed short packets to the transmission line as one multiplexed packet. This is a multiplexed packet assembling / transmitting unit for sending a multiplexed packet created by multiplexing the short packets stored in the buffer 502 to the destination packet transmission apparatus.

  In addition, in 504, redundant packets are assembled in different packet formats corresponding to the data types from the redundant data of the packet data transmitted to the destination terminal device, and assembled using the assembled redundant packets. A multiplexed packet receiving / decomposing means for receiving a multiplexed packet in which a short packet is multiplexed and decomposing the received multiplexed packet into individual short packets. A multiplexed packet receiving / decomposing unit that receives the multiplexed packets and decomposes them into individual short packets. 505 divides the short packet decomposed by the multiplexed packet receiving / decomposing means into a redundant packet and other information, and determines the data type based on the packet format of the divided redundant packet, and the determination result Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device based on the above, and here, the short packet input from the multiplexed packet receiving / decomposing unit 504 is referred to as a redundant packet. When the redundant packet is not an RTP header as a result of dividing into other information and determining based on the packet format of the redundant packet obtained by the division, a redundant packet replacement unit that restores the RTP packet from the redundant packet information It is.

  Reference numeral 506 denotes packet assembling means for assembling a packet to be transmitted to the original terminal device from the short packet information divided by the redundant packet replacing means as information other than the redundant packet. Here, the redundant packet replacing unit 505 An RTP packet assembling unit that assembles RTP packets from short packet information output as information other than redundant packets. Reference numeral 507 denotes terminal packet storage means for storing packets transmitted to the destination terminal device obtained by the redundant packet replacement means and the packet assembly means. Here, the RTP packet assembly section 506 or the redundant packet replacement section 505 It is an RTP packet accumulation buffer for temporarily storing assembled RTP packets. Reference numeral 508 denotes packet transmission means for transmitting the packet stored in the terminal packet storage means to the destination terminal device. Here, the RTP packet stored in the RTP packet storage buffer 507 is taken out and the IP packet is extracted. An IP packet assembly / transmission unit that transmits an IP packet to a VoIP terminal after assembling.

  509 designates a short packet as a short packet using a redundant packet consisting of header information of the packet received by the packet receiving means until the number of packets received by the packet receiving means reaches a predetermined number. This is a redundant packet control means for controlling to assemble. Here, the number of IP packets received by the IP packet receiving unit 101 is measured for each call, and a short packet is received until a predetermined number of IP packets of the same call are received. This is a redundant packet control unit that instructs the assembling unit 501 to assemble a short packet using an RTP header as a redundant packet.

Next, the operation will be described.
First, the operation when the packet transmission apparatus according to the fifth embodiment of the present invention receives an IP packet from a VoIP terminal will be described. In this case, the packet transmission apparatus first receives an IP packet from the VoIP terminal by the IP packet receiving unit 101 and outputs it to the data type determination unit 102 and the redundant packet control unit 106. Then, the data type determination unit 102 checks the IP packet input from the IP packet reception unit 101 and determines the type of data included in the IP packet. The operations of the IP packet receiving unit 101, the data type determining unit 102, the redundant packet assembling unit 103, and the redundant packet storage buffer 104 are the same as those in the first embodiment, and thus the description thereof is omitted.

  In this embodiment, audio data or redundant data of a control signal and an RTP header are transmitted as redundant packets. The packet lengths of these packets are set in advance so as to be different from each other. Here, the packet length of the redundant packet of voice data is 20 bytes, and the packet length of the redundant packet of the control signal is 9 bytes. Assume that the packet length of the redundant packet of the RTP header is set to 12 bytes.

  Thus, by setting the packet length of the redundant packet to a different packet length for each data type, the data type can be determined from the packet length of the redundant packet in the packet transmission device on the receiving side. Since it is not necessary to incorporate information indicating the type into the header information or the like, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed.

  On the other hand, the redundant packet control unit 509 identifies a call to which the IP packet input from the IP packet receiving unit 101 corresponds, and updates a counter for measuring the number of IP packet receptions prepared for each call. Then, in accordance with the number of IP packets received in the same call, a signal indicating which redundant data of voice data or control signal redundant data or RTP header is added is output. When the number of IP packets received for the same call is smaller than a predetermined number, a signal for controlling the short packet assembling unit 501 to assemble a short packet using a redundant packet consisting of an RTP header is output. When the number of received IP packets of the call exceeds a predetermined number, a short packet is transmitted to the short packet assembling unit 501 by using a normal redundant packet, for example, a redundant packet of voice data or redundant data of a control signal. Outputs a signal to control the assembly.

  Thereby, for example, a redundant packet consisting of an RTP header can be transmitted until a redundant packet of redundant data is transmitted. In the packet transmission apparatus on the receiving side, the redundant packet is acquired after acquiring the RTP header. Since the data is received, the original RTP packet (IP packet) can be accurately restored from the redundant packet. Further, since there is a transmission delay in the transmission of redundant data, the peak value of the transmission path load during redundant transmission can be suppressed by transmitting a redundant packet consisting of an RTP header during the transmission delay.

  Next, the short packet assembly unit 501 creates a short packet according to the signal input from the redundant packet control unit 509. FIG. 12 shows a packet format of a short packet created when the determination result is audio data. FIG. 13 shows a packet format of a short packet created when the determination result is a control signal.

  First, the short packet assembling unit 501 extracts only necessary information from the determination result input from the data type determining unit 102 and the IP / UDP / RTP header information of the received IP packet, and creates the header information of the short packet. To do. Here, the header information of the short packet does not store information that can be restored on the receiving side of the multiplexed packet among the information included in the IP packet received by the IP packet receiving unit 101, and stores information that cannot be restored accurately. It is comprised so that.

  In this way, the information that can be recovered from the multiplexed packet received by the packet transmission apparatus on the receiving side is not stored in the header information of the short packet, and the information that cannot be accurately recovered is stored in the header information of the short packet. In the packet transmission apparatus, the original RTP packet can be accurately restored from the short packet, the overhead of the header information of the short packet can be suppressed, and the peak value of the transmission path load during redundant transmission can be suppressed. .

  As shown in FIGS. 12 and 13, the header information of the short packet includes, for example, a destination VoIP terminal address, a sequence number, an encoding type, a short packet length, and a TimeStamp field. The destination VoIP terminal address is the IP address of the VoIP terminal that transmits the IP packet, and the sequence number stores a numerical value that increases by 1 with respect to the short packet of the same transfer destination based on the value of the SN field of the RTP header. To do. The encoding type is obtained by encoding the type of audio data encoding method. The short packet length stores the total value of the data length of the short packet payload including the header of the short packet and the redundant packet. In TimeStamp, the TimeStamp value of the RTP header is stored.

  Then, the short packet assembling unit 501 extracts the RTP packet payload from the received IP packet input from the data type determination unit 102 and stores it as the short packet payload.

  Furthermore, the short packet assembling unit 501 adds a redundant packet to the end of the payload of the short packet according to the signal input from the redundant packet control unit 509. For example, when a signal for adding an RTP header as a redundant packet is input from the redundant packet control unit 509, the short packet assembling unit 501 extracts the RTP header of the IP packet input from the data type determination unit 102 and It is added as a 12-byte redundant packet at the end of the payload.

In addition, when a signal for adding a normal redundant packet, for example, a redundant packet of redundant data of voice data or a control signal, is input from the redundant packet control unit 509, the short packet assembling unit 501 enters the redundant packet storage buffer 104. The stored redundant packet is extracted and added to the end of the short packet payload. For example, when a redundant packet is transmitted with a delay of one packet, the redundant packet corresponding to the previous short packet is extracted from the redundant packet storage buffer 104 and added to the end of the payload of the short packet. At this time, a redundant packet of 20 bytes is added for a redundant packet of voice data, and a redundant packet of 9 bytes is added for a redundant packet of a control signal.
Then, the short packet assembly unit 501 stores the created short packet in the short packet accumulation buffer 502.

  Next, the multiplexed packet assembling / transmitting unit 503 calculates the total length of the short packets stored in the short packet accumulation buffer 502, and if the calculated total length exceeds the preset threshold, The short packet stored in the packet accumulation buffer 502 is multiplexed to create a multiplexed packet shown in FIG. FIG. 14 is an explanatory diagram showing a packet format of the multiplexed packet. Then, the multiplexed packet assembly / transmission unit 503 sends the created multiplexed packet to the destination packet transmission apparatus.

  The above is the operation when the packet transmission apparatus receives an IP packet from the VoIP terminal. Next, the operation of the packet transmission apparatus when a multiplexed packet is received from the counterpart packet transmission apparatus will be described. In this case, first, the packet transmission apparatus receives the multiplexed packet transmitted from the destination packet transmission apparatus by the multiplexed packet receiving / decomposing unit 504, decomposes the multiplexed packet into individual short packets, and then transmits each short packet. To the redundant packet replacement unit 505.

Next, the redundant packet replacing unit 505 divides the short packet decomposed by the multiplexed packet receiving / decomposing unit 504 into redundant packets and other information, and sets the data type based on the packet format of the divided redundant packets. The original RTP packet is restored from the redundant packet based on the determination result.
First, the redundant packet replacement unit 505 checks the header information of the short packet input from the multiplexed packet reception / decomposition unit 504, and calculates the header and payload of the short packet and the data length of the redundant packet. For example, a table is prepared in advance so that the header length and payload length of the short packet can be uniquely determined from the encoding type value of the short packet header. Then, the redundant packet replacement unit 505 outputs the header and payload of the short packet to the RTP packet assembly unit 506.

  Further, the redundant packet replacement unit 505 determines the contents of the redundant packet from the data length of the redundant packet. Here, depending on the type of data transmitted by the packet transmission device as a redundant packet, the packet length is fixed as a fixed value in advance, such as 12 bytes for the RTP header, 20 bytes for the voice data, and 9 bytes for the redundant header and control signal. Since it is set, when the redundant packet is 12 bytes, the redundant packet is determined as the RTP header. Then, the RTP header information is stored, and the RTP header information is output to the RTP packet assembling unit 506. If the redundant packet is 20 bytes, it is determined that the redundant packet is voice data, and the RTP header information corresponding to the voice data is determined using the header information of the short packet and the information of the RTP header already stored. , And an RTP packet having voice data as a payload is assembled, and the assembled RTP packet is stored in the RTP packet accumulation buffer 507. When the redundant packet is 9 bytes, it is determined that the redundant packet is a combination of the redundant header and the control signal, and RTP header information corresponding to the control signal is generated using the header information of the short packet and the redundant header information. Then, an RTP packet with the control signal as a payload is assembled. Then, the redundant packet replacement unit 505 stores the assembled RTP packet in the RTP packet accumulation buffer 507.

  When storing the assembled RTP packet in the RTP packet storage buffer 507, the redundant packet replacement unit 505 checks the SN field included in the header of the RTP packet stored in the RTP packet storage buffer 507, and determines the SN field The assembled RTP packets are stored in places where the values of are consecutive. At this time, if an RTP packet having the same SN value is already stored, the assembled RTP packet is discarded.

  Next, the RTP packet assembling unit 506 uses the RTP header information input from the redundant packet replacement unit 505 and the header information of the short packet input from the redundant packet replacement unit 505 to output from the redundant packet replacement unit 505. RTP header information corresponding to the payload of the input short packet is generated, and the RTP packet is assembled together with the payload of the short packet. Then, the RTP packet assembling unit 506 stores the assembled RTP packet in the RTP packet accumulation buffer 507.

  Next, the IP packet assembly / transmission unit 508 takes out the RTP packet stored in the RTP packet accumulation buffer 507, adds an IP / UDP header, assembles the IP packet, and then sends the IP packet to the VoIP terminal. .

  As described above, according to the fifth embodiment of the present invention, by assembling redundant packets of redundant data in different packet formats corresponding to the data types of data included in the received packet, the receiving side of the redundant packet In addition to determining the data type from the packet format of the redundant packet, the redundant packet can be formed with only necessary information corresponding to the data type, so that the overhead of redundant data can be suppressed and the peak value of the transmission line load during redundant transmission The effect that it can suppress is acquired. For example, by assembling redundant packets with different packet formats for voice data and control signals contained in IP packets, the overhead of redundant data can be suppressed and the peak value of the transmission line load during redundant transmission can be suppressed. The effect is obtained.

In addition, the packet format of the redundant packet is configured such that, among the information included in the received packet, information that can be restored on the receiving side of the transmission path packet is not stored, and information that cannot be restored accurately is stored. Since it is possible to form a redundant packet with only the information necessary to accurately restore the packet, it is possible to accurately restore the packet in the packet transmission device on the receiving side, and it is possible to suppress the overhead of redundant data, and the transmission line load during redundant transmission The effect that the peak value of can be suppressed is obtained.
For example, when performing redundant transmission in a transmission path in which voice data and control signals are mixedly transmitted, the redundant packet assembling unit 103 transmits only voice data as a redundant packet without adding header information, and the redundant packet The replacement unit 505 identifies the type of redundant packet from the data length of the redundant packet, thereby realizing redundant transmission when voice and control signals coexist on the transmission line with the highest load during redundant transmission of voice data. On the other hand, it is possible to obtain an effect of suppressing an increase in overhead of redundant packets and reducing a peak value of a transmission line load. For example, when the conventional redundant transmission method defined in RFC2198 is applied to a packet transmission apparatus, 1-byte header information is added to voice data and 4-byte header information is added to the voice data redundant packet. Therefore, the data length of the short packet is the G. When voice data encoded by the 729 method is transmitted in the form of an IP packet at a cycle of 20 msec, the data length of the short packet header is 7 bytes (destination VoIP terminal address: 4 bytes, sequence number: 1 byte, encoding type: 1 byte, short packet Length: 1 byte), 7 + 1 + 20 + 4 + 20 = 52 bytes. On the other hand, in Embodiment 1 of the present invention, header information is not added to the redundant packet of audio data, so the data length of the short packet is 7 + 20 + 20 = 47 bytes. Therefore, in Embodiment 1 of the present invention, the data length of the short packet can be reduced by about 10%.

Also, the header information of the short packet is not stored in the information included in the packet received by the packet receiver 101, but information that can be restored on the receiving side of the multiplexed packet is not stored, and information that cannot be restored accurately is stored. By configuring, a short packet can be formed with only necessary information to accurately restore the RTP packet, so that the packet can be accurately restored in the packet transmission device on the receiving side, and the peak of the transmission line load during redundant transmission The effect that the value can be suppressed is obtained.

  In addition, since the redundant packets are configured to have different packet lengths corresponding to the data types, the data type can be determined from the packet length of the redundant packets in the packet transmission device on the receiving side. Since it is not necessary to incorporate information indicating the packet type of the packet into the header information or the like, the overhead of redundant data can be suppressed, and the peak value of the transmission path load during redundant transmission can be suppressed. .

  In addition, by assembling a short packet using a redundant packet which is an RTP header and has a packet format different from the redundant packet of redundant data, the information of the RTP header is changed to the header information of the redundant packet of redundant data. Since the receiving side can determine from the packet length that the packet is a redundant packet consisting of an RTP header, there is no need to incorporate information indicating the packet type of the redundant packet into the header information or the like. Therefore, the overhead of redundant data can be suppressed, and the peak value of the transmission line load during redundant transmission can be suppressed.

  Further, until the number of packets received by the IP packet receiving unit reaches a predetermined number, control is performed so as to assemble a transmission path packet using redundant packets made up of RTP headers, until redundant packets of redundant data are transmitted. The RTP header redundant packet can be transmitted, and the receiving side packet transmission apparatus receives the redundant data after obtaining the RTP header, so that the original RTP packet (IP packet) is received from the redundant packet. ) Can be restored accurately. Also, since there is a transmission delay in the transmission of redundant data, there is an effect that the peak value of the transmission line load at the time of redundant transmission can be suppressed by transmitting the redundant packet of the RTP header during the transmission delay. can get.

  Also, the received multiplexed packet is broken down into individual short packets, the broken short packets are divided into redundant packets and other information, and the data type is determined based on the packet format of the divided redundant packets. Then, by restoring the RTP packet (IP packet) from the redundant packet based on the determination result, the redundant data can be transmitted with the redundant packet formed only by the necessary information corresponding to the data type. The overhead of the transmission line can be suppressed, and the peak value of the transmission line load at the time of redundant transmission can be suppressed.

  In the fifth embodiment of the present invention, redundant packet control unit 509 specifies a call corresponding to the IP packet input from IP packet receiving unit 101, and measures the number of IP packet receptions prepared for each call. The redundant packet control unit 509 has an I / F with an external server that manages the call connection of the VoIP terminal, and obtains information on the call start / stop of the VoIP terminal from the external server. You may make it do. In addition, a counter for measuring the number of IP packet receptions prepared for each call may be reset according to information acquired from an external server.

  In the fifth embodiment of the present invention, redundant packet control unit 509 specifies a call corresponding to the IP packet input from IP packet receiving unit 101, and measures the number of IP packet receptions prepared for each call. However, the counter may be reset when a packet of the same call is not received for a certain period of time.

  In the fifth embodiment of the present invention, redundant packet control unit 509 identifies a call corresponding to the IP packet input from IP packet receiving unit 101 and measures the number of IP packet receptions prepared for each call. However, it is also possible to check changes in the SN and TimeStamp of the RTP header of the received IP packet and reset the counter when the continuity of the packet is lost. For example, if the VoIP terminal is G.264. When voice data encoded by the 729 method is transmitted as an IP packet in a cycle of 20 msec, normally, the SN of the RTP header is incremented by 1 for each IP packet, and TimeStamp is +160. Therefore, when a certain number or more of IP packets whose TimeStamp change amount does not match the SN change amount compared to the IP packet received immediately before are received, it is determined that the continuity of the packet is lost. Good.

  In the fifth embodiment of the present invention, ITU-T Recommendation G. The data encoded by the 8kbit / s CS-ACELP system conforming to the G.729 standard is used as voice data. Data encoded by a method other than 729 may be used as audio data.

  In the fifth embodiment of the present invention, the control signal is a DTMF signal transmitted by the DTMF out-of-band transmission system defined by RFC2833. Information other than the DTMF signal, such as a signal, may be used as the control signal.

Embodiment 6 FIG.
In the sixth embodiment, the connection control shown in the second embodiment is applied to a packet transmission apparatus that multiplexes and transmits IP packets received from one or a plurality of VoIP terminals.

  FIG. 15 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 6 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, reference numeral 601 denotes a short packet assembling unit that assembles a short packet of a packet received by the packet receiving unit using the redundant packet stored in the redundant packet accumulating unit. Here, the data type determining unit 102 This is a short packet assembling unit that creates a short packet from the IP packet input from the redundant packet stored in the redundant packet storage buffer 104. Reference numeral 602 denotes multiplexed packet assembling / transmitting means for multiplexing the short packets stored in the short packet storing means and sending the multiplexed short packets to the transmission line as one multiplexed packet. This is a multiplexed packet assembling / transmitting unit for sending a multiplexed packet created by multiplexing the short packets stored in the buffer 502 to the destination packet transmission apparatus.

  Reference numeral 603 denotes a redundant packet assembled in different packet formats corresponding to the data type from the redundant data of the packet transmitted to the destination terminal device, and a short packet assembled using the assembled redundant packet is multiplexed. The multiplexed packet receiving / decomposing means for receiving the multiplexed packet and decomposing the received multiplexed packet into individual short packets. Here, the multiplexed packet transmitted from the destination packet transmission device Is a multiplexed packet receiving / decomposing unit that receives and resolves each short packet. 604 divides the short packet decomposed by the multiplexed packet receiving / decomposing means into a redundant packet and other information, and determines the data type based on the packet format of the divided redundant packet, and the determination result Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device based on the above-mentioned redundant packet, wherein the short packet input from the multiplexed packet receiving / decomposing unit 603 is a header, payload The redundant packet replacement unit divides the packet into redundant packets and assembles the RTP packet from the information of the redundant packet when the divided redundant packet is not the RTP header. Reference numeral 605 denotes packet transmission means for transmitting the packet stored in the terminal packet storage means to the destination terminal device. Here, the RTP packet stored in the RTP packet storage buffer 507 is taken out and IP / UDP An IP packet assembly / transmission unit that attaches a header, assembles an IP packet, and transmits the packet to a VoIP terminal.

  Reference numeral 606 denotes connection control means for monitoring call connection between terminal apparatuses and adding packet header information received by the packet receiving means to packets for controlling call connection between terminal apparatuses. The multiplexed packet receiving / decomposing unit 603 analyzes the multiplexed packet (IP packet) and acquires packet header information (RTP header information). Here, connection control for monitoring call connection operations between VoIP terminals and exchanging RTP header information of voice data transmitted from a VoIP terminal to which a new call is connected, with a packet transmission apparatus at the other end Part.

Next, the operation will be described.
There are three states of call connection between VoIP terminals monitored by the connection control unit 606: call connection undetected, call connection start, and call connection start completion. The connection control unit 606 detects the start of the call connection when the call connection is not detected, and detects the completion of the start of the call connection when the call connection is started. Then, the connection control unit 606 adds the header information of the packet received by the packet receiving unit to the packet for controlling the call connection between the terminal apparatuses from when the call connection is started until the start completion is detected. On the receiving side, the header information is acquired after the call connection is started until the start completion is detected. Hereinafter, the operation of each state of call connection will be described.

  First, regarding the operation of the packet transmission apparatus in a state where the connection control unit 606 has not detected the call connection operation of the VoIP terminal, the connection control unit 207 shown in the second embodiment has detected the call connection operation of the VoIP terminal. Since the operation is similar to the operation in the absence state, the description is omitted.

Next, the operation of the packet transmission apparatus when the connection control unit 606 detects the start of call connection of the VoIP terminal will be described.
First, the operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, the packet transmission apparatus receives the IP packet from the VoIP terminal by the IP packet receiving unit 201 and outputs the received IP packet to the connection control unit 606. Next, the connection control unit 606 determines whether or not the IP packet input from the IP packet receiving unit 201 is call connection operation information. When it is determined that the input IP packet is not call connection operation information, the connection control unit 606 determines whether the IP packet is voice data. For example, as shown in FIG. 2, the value of the PT field included in the RTP header of the input IP packet is inspected and matches the value of the voice coding method described in the SIP message that detected the start of the call connection. In this case, it is determined that the input IP packet is voice data. If it is determined that the input IP packet is voice data, the connection control unit 606 extracts the information of the RTP header from the IP packet and temporarily stores it.
On the other hand, when it is determined that the IP packet input from the IP packet receiving unit 201 is call connection operation information, the connection control unit 606 determines whether the information of the RTP header is already stored. If the connection control unit 606 does not store the RTP header information, the input IP packet information is temporarily stored. On the other hand, when the connection control unit 606 has already stored the information of the RTP header, the IP packet obtained by adding the RTP header information to the call connection operation information is assembled, and the assembled IP packet is assembled into the multiplexed packet The data is output to the transmission unit 602. At that time, the connection control unit 606 analyzes the information of the call connection operation included in the output IP packet, and detects the completion of the start of the call connection. FIG. 16 shows an example of an IP packet obtained by adding RTP header information to call connection operation information.
Then, the multiplexed packet assembling / transmitting unit 602 outputs the multiplexed packet (IP packet) including the call connection operation and RTP header information input from the connection control unit 606 to the destination packet transmission device.

  Next, the operation when the connection control unit 606 receives a multiplexed packet (IP packet) including call connection operation information from the destination packet transmission apparatus in a state where the start of the call connection of the VoIP terminal is detected. State. In this case, the packet transmission apparatus outputs the multiplexed packet (IP packet) received from the counterpart packet transmission apparatus by the multiplexed packet receiving / decomposing unit 603 to the connection control unit 606. Then, the connection control unit 606 analyzes the IP packet received from the multiplexed packet reception / decomposition unit 603 and acquires header information of the RTP packet of the IP packet, for example, RTP header information of the voice data. Then, the connection control unit 606 outputs the RTP header information of the acquired voice data to the redundant packet replacement unit 604. Further, the VoIP terminal that is the call connection partner is specified from the call connection operation information included in the received IP packet, and the information of the RTP header is deleted from the input IP packet, and the IP packet assembly / transmission unit 605 is selected. Output to. The IP packet assembly / transmission unit 605 transmits the IP packet input from the connection control unit 606 to the VoIP terminal. Also, the redundant packet replacement unit 604 outputs the RTP header information input from the connection control unit 606 to the RTP packet assembly unit 506.

The above is the operation of the packet transmission apparatus when the connection control unit 606 detects the start of call connection of the VoIP terminal. Next, the operation of the packet transmission apparatus in a state in which the connection control unit 606 detects the completion of the call connection of the VoIP terminal will be described.
First, an operation when the packet transmission apparatus receives an IP packet of voice data from a VoIP terminal will be described. In this case, the packet transmission apparatus receives an IP packet from the VoIP terminal by the IP packet receiving unit 201, and determines whether or not the received IP packet is call connection operation information. When the IP packet receiving unit 201 determines that the received IP packet is not call connection operation information, the IP packet receiving unit 201 outputs the received IP packet to the data type determining unit 102. The subsequent operations of the data type determination unit 102, the redundant packet assembly unit 103, and the redundant packet storage buffer 104 are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, the short packet assembling unit 601 extracts only necessary information from the determination result input from the data type determining unit 102 and the information of the IP / UDP / RTP header of the received IP packet, and extracts the header information of the short packet. create. Then, the short packet assembling unit 601 stores the payload of the RTP packet included in the received IP packet as the payload of the short packet. Since the subsequent operations of the short packet accumulation buffer 502 and the multiplexed packet assembling / transmitting unit 602 are the same as those in the fifth embodiment, description thereof is omitted.

  Next, an operation when the connection control unit 606 receives a multiplexed packet from the counterpart packet transmission apparatus in a state where the start of call connection of the VoIP terminal is detected will be described. In this case, the packet transmission apparatus receives the multiplexed packet transmitted from the counterpart packet transmission apparatus by the multiplexed packet receiving / decomposing unit 603, decomposes the multiplexed packet into individual short packets, and then transmits each short packet. To the redundant packet replacement unit 604.

  Next, the redundant packet replacement unit 604 uses the header information of the short packet input from the multiplexed packet reception / decomposition unit 203 to calculate the header and payload of the short packet and the data length of the redundant packet. Then, the redundant packet replacement unit 604 outputs the header and payload of the short packet to the RTP packet assembly unit 506. Further, the redundant packet replacement unit 604 determines the contents of the redundant packet from the data length of the redundant packet. For example, when the data length to be transmitted as a redundant packet is set as a fixed value in advance, such as 20 bytes for voice data and 9 bytes for redundant header and control signal, if the redundant packet is 20 bytes, the redundant length The packet is determined as voice data, RTP header information corresponding to the voice data is generated using the header information of the short packet and the information of the RTP header already stored, and the RTP packet with the voice data as the payload is After the assembly, the assembled RTP packet is stored in the RTP packet accumulation buffer 507. When the redundant packet is 9 bytes, it is determined that the redundant packet is a combination of the redundant header and the control signal, and the short packet header information, the RTP header information already stored, and the redundant header information are used. RTP header information corresponding to the control signal is generated, and an RTP packet using the control signal as a payload is assembled. Then, the redundant packet replacement unit 604 stores the assembled RTP packet in the RTP packet accumulation buffer 507.

  Note that the operations of the RTP packet assembly unit 506 and the RTP packet storage buffer 507 are the same as those in the fifth embodiment, and thus description thereof is omitted. Next, the IP packet assembly / transmission unit 605 takes out the RTP packet stored in the RTP packet accumulation buffer 507, adds an IP / UDP header, assembles the IP packet, and then sends the IP packet to the VoIP terminal. .

  As described above, according to the sixth embodiment of the present invention, the connection control unit 606 determines whether or not the input packet is call connection operation information, and detects the connection operation. By monitoring the call connection operation and notifying the other party's packet transmission apparatus as part of the call connection operation information of the RTP header contained in the IP packet of the voice data received from the VoIP terminal, In the packet transmission apparatus, the RTP header corresponding to the redundant packet can be accurately restored. Further, since it is not necessary to send the RTP header information included in the IP packet of the voice data received from the VoIP terminal as the header information of the redundant packet consisting of redundant data, the IP packet of the voice data received from the VoIP terminal It is not necessary to incorporate the information of the included RTP header into the header information of the redundant packet, and the RTP header information included in the IP packet of the voice data received from the VoIP terminal can be transmitted as a packet for controlling the call connection. The overhead of redundant data can be suppressed, and the effect that the peak value of the transmission line load during redundant transmission can be suppressed can be obtained.

  In addition, the connection control unit 606 monitors the call connection operation of the VoIP terminal, and uses information on the RTP header included in the IP packet of the voice data received from the VoIP terminal as information on the call connection operation (packet for controlling the call connection). By notifying the other party's packet transmission device as a part of the packet, it becomes possible to always add voice data or a control signal to the transmission path packet as a redundant packet, and the effect of improving the resistance to packet loss in the transmission path. can get.

Embodiment 7 FIG.
In the seventh embodiment, the connection / redundant packet control shown in the third embodiment is applied to a packet transmission apparatus that multiplexes and transmits IP packets received from one or a plurality of VoIP terminals.

  FIG. 17 is a block diagram showing a configuration of a packet transmission apparatus according to Embodiment 7 of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, reference numeral 701 designates a redundancy consisting of header information of a packet received by the packet receiving means to the short packet assembling means only after the call connection between the terminal devices is monitored and the call connection is started. It is a connection / redundant packet control means for controlling so as to assemble a short packet using a packet. Here, a redundant packet is detected only immediately after a call connection operation between VoIP terminals is detected and a new call connection is completed. A connection / redundant packet control unit that controls to add an RTP header to a short packet instead of voice data and a control signal.

Next, the operation will be described.
First, regarding the operation of the packet transmission apparatus in a state where the connection / redundant packet control unit 701 has not detected the call connection operation of the VoIP terminal, the connection control unit 606 described in the sixth embodiment performs the call connection operation of the VoIP terminal. Since this is the same as the operation of the packet transmission apparatus in a state where no is detected, the description thereof is omitted.

Next, the operation of the packet transmission apparatus when the connection / redundant packet control unit 701 detects the start of call connection of the VoIP terminal will be described.
First, an operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, the packet transmission apparatus receives the IP packet from the VoIP terminal by the IP packet receiving unit 201 and outputs the IP packet to the connection / redundant packet control unit 701. Then, the connection / redundant packet control unit 701 determines whether the IP packet input from the IP packet receiving unit 201 is call connection operation information. If it is determined that the IP packet input from the IP packet receiving unit 201 is call connection operation information, the connection / redundant packet control unit 701 transmits packet transmission corresponding to the partner VoIP terminal from the call connection operation information. The device is specified, and the destination of the IP packet including the information of the call connection operation is set in the specified packet transmission device and output to the multiplexed packet assembling / transmitting unit 602. Further, the connection / redundant packet control unit 701 analyzes the call connection operation information and detects the completion of the call connection. When a call connection completion is detected, a new counter for storing the number of IP packet receptions corresponding to the call is prepared, and the counter is initialized.
Then, the multiplexed packet assembling / transmitting unit 602 outputs the IP packet input from the connection / redundant packet control unit 701 to the destination packet transmission apparatus.

  Then, after the connection / redundant packet control unit 701 detects the completion of the connection of the call of the VoIP terminal, the IP packet receiving unit 201 receives the IP packet and the prepared counter reaches once, that is, a new call is made. Only after the connection is completed, the connection / redundant packet control unit 701 controls the short packet assembling unit 501 to assemble the transmission path packet using the redundant packet formed of the RTP header.

  Regarding the operation of the packet transmission apparatus in a state where the connection / redundant packet control unit 701 detects the completion of the connection of the call of the VoIP terminal, the redundant packet control unit 509 in the operation of the packet transmission apparatus shown in the fifth embodiment Since the predetermined number when controlling the short packet assembling unit 501 is 1 (initial value of the counter + 1), the description is omitted.

  Next, an operation when the connection / redundant packet control unit 701 detects the start of call connection of the VoIP terminal and receives an IP packet including call connection operation information from the counterpart packet transmission apparatus will be described. In this case, the packet transmission apparatus outputs the IP packet received from the destination packet transmission apparatus by the multiplexed packet receiving / decomposing unit 603 to the connection / redundant packet control unit 701. If the connection / redundant packet control unit 701 determines that the IP packet input from the multiplexed packet receiving / decomposing unit 603 is information on the call connection operation, the connection / redundant packet control unit 701 analyzes the information on the call connection operation to analyze the call connection. The VoIP terminal as the other party is specified, and the input IP packet is output to the IP packet assembling / transmitting unit 605. Then, the IP packet assembling / transmitting unit 605 transmits the IP packet input from the connection / redundant packet control unit 701 to the VoIP terminal.

The above is the operation of the packet transmission apparatus when the connection / redundant packet control unit 701 detects the start of call connection of the VoIP terminal.
Note that the operation of the packet transmission apparatus in the state where the connection / redundant packet control unit 701 detects the completion of the call connection of the VoIP terminal is the same as the operation of the packet transmission apparatus described in the fifth embodiment, and therefore will be described. Omitted.

  As described above, according to the seventh embodiment of the present invention, the connection / redundant packet control unit 701 determines whether the input packet is call connection operation information, and detects the connection operation. The call connection operation of the VoIP terminal is monitored, and a short packet is assembled and transmitted using a redundant packet consisting of RTP header information instead of a redundant packet of voice data or control signal only immediately after the call connection is completed. By controlling in this way, the RTP header corresponding to the redundant packet can be accurately restored in the packet transmission apparatus at the other end. Further, since it is not necessary to send RTP header information as redundant packet header information consisting of redundant data, it is not necessary to incorporate information indicating the packet type of the redundant packet into the header information or the like, and the redundant packet is transmitted as a redundant packet. Since the RTP header information can be transmitted as a redundant packet of the first IP packet in which no data exists, the overhead of redundant data can be suppressed, and the peak value of the transmission path load during redundant transmission can be suppressed. Is obtained.

  In addition, the connection / redundant packet control unit 701 monitors the call connection operation of the VoIP terminal, and only after the call connection is completed, the redundancy comprising the information of the RTP header instead of the redundant packet of the voice data and the control signal. By controlling so that short packets are assembled and transmitted using packets, only when voice data immediately before transmission as a redundant packet or a leading IP packet without a control signal is transmitted, voice data or The information of the RTP header can be transmitted instead of the control signal, and the effect that the packet loss tolerance on the transmission path is improved can be obtained.

Embodiment 8 FIG.
In the eighth embodiment, the redundant packet control shown in the fourth embodiment is applied to a packet transmission apparatus that multiplexes and transmits IP packets received from one or a plurality of VoIP terminals.

  FIG. 18 is a block diagram showing a configuration of a packet transmission apparatus according to the eighth embodiment of the present invention. In this figure, the same reference numerals are given to the same or corresponding parts as in the previous figures, and the description will be omitted. In this figure, reference numeral 801 denotes information on the header of the packet received by the packet receiving means when the data included in the packet received by the packet receiving means is silent audio data to the short packet assembling means. Redundant packet control means for controlling to assemble a short packet using a redundant packet consisting of the following: In this case, the data included in the IP packet received by the packet receiving unit 101 with respect to the short packet assembling unit 501 is a silent voice. In the case of data, instead of the redundant packet of the silent voice data, control is performed so that a short packet is assembled using a redundant packet that is information of the RTP header of the IP packet received by the packet receiving unit 101. Yes, the IP packet received by the IP packet receiving unit 101 The short packet assembly unit 105 is instructed to output an RTP header as a redundant packet until a predetermined number of IP packets of the same call are received. Is a redundant packet control unit that controls to assemble a short packet by using a redundant packet of an RTP header instead of a redundant packet of an IP packet that has been determined to be silent by the silence detecting unit 401 even after a predetermined number is received.

Next, the operation will be described.
First, the operation when the packet transmission apparatus receives an IP packet from a VoIP terminal will be described. In this case, the packet transmission apparatus first receives an IP packet from the VoIP terminal by the IP packet receiving unit 101, and outputs it to the data type determination unit 102 and the redundant packet control unit 801. Then, the data type determination unit 102 determines the data type of the input IP packet, and outputs the input IP packet and the determination result of the IP packet to the redundant packet assembly unit 103. The operation of determining the type of data included in the IP packet by the data type determination unit 102 is the same as that in the first embodiment, and thus the description thereof is omitted. If the data type determination unit 102 determines that the data of the IP packet is not a control signal, the data type determination unit 102 regards the IP packet as voice data and outputs it to the silence detection unit 401. Note that the operations of the redundant packet assembling unit 103 and the redundant packet storage buffer 104 are the same as those in the first embodiment, and thus the description thereof is omitted.

Next, as in the fourth embodiment, the silence detection unit 401 determines whether or not the voice data included in the input IP packet is silent, and determines whether the voice data is voiced or silent according to the determination result. The indicated signal is output to the redundant packet control unit 801.
Then, the redundant packet control unit 801 identifies a call to which the IP packet input from the IP packet receiving unit 101 corresponds, and updates a counter for measuring the number of IP packet receptions prepared for each call. When the number of IP packets received for the same call is smaller than a predetermined number, a signal for adding an RTP header as a redundant packet is output to the short packet assembling unit 105. Further, when the number of IP packets received for the same call exceeds a predetermined number, an output signal is determined according to the signal input from the silence detection unit 401. For example, when a signal indicating the sound of audio data is received from the silence detection unit 401, a signal for adding a normal redundant packet in accordance with the timing at which the redundant packet corresponding to the signal indicating sound is added to the short packet Is output to the short packet assembly unit 501. In addition, when a signal indicating silence of the audio data is received from the silence detection unit 401, a signal for adding an RTP header as a redundant packet in accordance with the timing at which the redundant packet corresponding to the signal indicating silence is added to the short packet. The data is output to the short packet assembly unit 501.

  The operations of the short packet assembling unit 501, the short packet accumulating buffer 502, and the multiplexed packet assembling / transmitting unit 503 are the same as those in the fifth embodiment, and thus description thereof is omitted.

  The above is the operation when the packet transmission apparatus receives an IP packet from the VoIP terminal. The operation when a multiplexed packet is received from the counterpart packet transmission apparatus is the same as that of the fifth embodiment, and thus the description thereof is omitted.

  As described above, according to the eighth embodiment of the present invention, the silence detection unit 401 determines whether or not the voice data input from the VoIP terminal is silent, and the voice data is silent voice data. In addition, the redundant packet control unit 801 controls the short packet assembling unit 501 to assemble a short packet by using a redundant packet made up of RTP header information instead of a redundant packet of audio data determined to be silent. Thus, even when a burst loss occurs in the transmission path, it is possible to transmit the RTP header included in the IP packet received from the VoIP terminal to the destination packet transmission device. In the destination packet transmission device, When creating an IP packet from a redundant packet, the RTP header corresponding to the redundant packet is accurately restored. There is an advantage that it is Rukoto.

It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the packet format of an IP packet. It is explanatory drawing which shows the data format of a RTP header. It is explanatory drawing which shows the outline | summary of each item of a RTP header. It is explanatory drawing which shows the packet format of the redundant packet of a control signal. It is explanatory drawing which shows the packet format of a transmission path packet. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 2 of this invention. It is explanatory drawing which shows the IP packet which added the transmission delay information of the redundant data to the information of call connection operation | movement. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 3 of this invention. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 4 of this invention. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 5 of this invention. It is explanatory drawing which shows the packet format of a short packet. It is explanatory drawing which shows the packet format of a short packet. It is explanatory drawing which shows the packet format of a multiplexed packet. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 6 of this invention. It is explanatory drawing which shows an example of the IP packet which added the information of RTP header to the information of call connection operation | movement. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 7 of this invention. It is a block diagram which shows the structure of the packet transmission apparatus by Embodiment 8 of this invention.

Explanation of symbols

  101 IP packet receiving unit, 102 data type determining unit, 103 redundant packet assembling unit, 104 redundant packet storage buffer, 105 transmission path packet assembling unit, 106 transmission path packet transmitting unit, 107 transmission path packet receiving unit, 108 redundant packet replacement unit 109 IP packet storage buffer, 110 IP packet transmission unit, 111 redundant packet control unit, 201 IP packet reception unit, 202 transmission path packet assembly unit, 203 transmission path packet transmission unit, 204 transmission path packet reception unit, 205 redundant packet replacement , 206 IP packet transmission unit, 207 connection control unit, 301 connection / redundant packet control unit, 401 silence detection unit, 402 redundant packet control unit, 501 short packet assembly unit, 502 short packet storage buffer 503, multiplexed packet assembly / transmission unit, 504 multiplexed packet reception / decomposition unit, 505 redundant packet replacement unit, 506 RTP packet assembly unit, 507 RTP packet storage buffer, 508 IP packet assembly / transmission unit, 601 short packet storage Buffer, 602 Multiplexed packet assembly / transmission unit, 603 Multiplexed packet reception / decomposition unit, 604 Redundant packet replacement unit, 605 IP packet assembly / transmission unit, 701 Connection / redundant packet control unit, 801 Redundant packet control unit.

Claims (18)

A packet receiving means for receiving a plurality of continuously transmitted packets;
Data type determining means for determining the data type of data included in the packet received by the packet receiving means;
Based on the determination result of the data type determination means, redundant packet assembly means for assembling redundant packets of redundant data of the received packets in different packet formats corresponding to the data types;
Redundant packet storage means for storing redundant packets assembled in the redundant packet assembly means;
Transmission path packet assembling means for assembling a transmission path packet of the packet received by the packet receiving means using the redundant packet stored in the redundant packet storage means;
A packet transmission apparatus comprising: a transmission path packet transmission means for transmitting a transmission path packet assembled by the transmission path packet assembly means to the transmission path.   The packet format of the redundant packet is such that information that can be restored on the receiving side of the transmission path packet is not stored in the information included in the packet received by the packet receiving means, and information that cannot be restored accurately is stored. The packet transmission apparatus according to claim 1, wherein the packet transmission apparatus is configured.   The transmission path packet assembling means is transmission delay information indicating a transmission delay of the redundant data, and assembles the transmission path packet by using a redundant packet having a packet format having a packet length different from that of the redundant packet of the redundant data. The packet transmission device according to claim 1, wherein the packet transmission device is configured as follows.   Redundant packet control for controlling the transmission path packet assembling means to assemble the transmission path packet using the redundant packet consisting of the transmission delay information until the number of packets received by the packet receiving means reaches a predetermined number. 4. The packet transmission apparatus according to claim 3, further comprising means. Connection control means for monitoring call connection between terminal devices and adding transmission delay information indicating a transmission delay of the redundant data to a packet for controlling the call connection between terminal devices,
The packet transmission apparatus according to claim 1, wherein the transmission delay information is transmitted as a part of a packet for controlling a call connection between terminal apparatuses.   A connection that monitors call connection between terminal devices and controls the transmission line packet assembling means to assemble a transmission line packet using the redundant packet consisting of the transmission delay information only immediately after the call connection is started. 4. The packet transmission apparatus according to claim 3, further comprising: redundant packet control means.   When the data included in the packet received by the packet receiving means is silent audio data, the transmission path packet assembly means is configured to assemble a transmission path packet using the redundant packet consisting of the transmission delay information. 4. The packet transmission apparatus according to claim 3, further comprising redundant packet control means for controlling. Transmission in which redundant packets are assembled in different packet formats corresponding to the data types from the redundant data of the packets transmitted to the destination terminal device, and the transmission path packets assembled using the assembled redundant packets are received. Route packet receiving means;
The transmission path packet received by the transmission path packet receiving means is divided into a packet to be transmitted to a destination terminal device and a redundant packet, and the data type is determined based on the packet format of the redundant packet, and the determination result Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device based on
Terminal packet storage means for storing packets transmitted to the destination terminal device obtained by the redundant packet replacement means;
A packet transmission apparatus comprising: packet transmission means for transmitting packets stored in the terminal packet storage means to the destination terminal apparatus. A packet receiving means for receiving a plurality of continuously transmitted packets;
Data type determining means for determining the data type of data included in the packet received by the packet receiving means;
Based on the determination result of the data type determination means, redundant packet assembly means for assembling redundant packets of redundant data of the received packets in different packet formats corresponding to the data types;
Redundant packet storage means for storing redundant packets assembled in the redundant packet assembly means;
Short packet assembling means for assembling a short packet of the packet received by the packet receiving means using the redundant packet stored in the redundant packet storing means;
Short packet storage means for storing short packets assembled in the short packet assembly means;
A packet transmission apparatus comprising: multiplexed packet assembling / transmitting means for multiplexing short packets stored in the short packet storage means and sending the multiplexed short packets as one multiplexed packet to a transmission line .   The packet format of the redundant packet is such that information that can be restored on the receiving side of the multiplexed packet is not stored, and information that cannot be accurately restored is stored among the information included in the packet received by the packet receiving means. The packet transmission device according to claim 9, wherein the packet transmission device is configured.   In the header information of the short packet, information that can be restored on the receiving side of the multiplexed packet is not stored in the information included in the packet received by the packet receiving unit, and information that cannot be restored accurately is stored. The packet transmission device according to claim 9, wherein the packet transmission device is configured.   The packet transmission device according to claim 1 or 9, wherein the packet format of the redundant packet is configured to have different packet lengths corresponding to data types.   The short packet assembling means is information of a header of a packet received by the packet receiving means, and assembles a short packet by using a redundant packet having a packet format having a packet length different from that of the redundant packet of the redundant data. The packet transmission device according to claim 9, wherein the packet transmission device is configured.   The short packet assembling means is configured to assemble a short packet using a redundant packet consisting of header information of the packet received by the packet receiving means until the number of packets received by the packet receiving means reaches a predetermined number. 14. The packet transmission apparatus according to claim 13, further comprising redundant packet control means for controlling the packet transmission. A connection control unit that monitors call connection between terminal devices and adds packet header information received by the packet reception unit to a packet that controls call connection between terminal devices;
10. The packet transmission apparatus according to claim 9, wherein the packet receiving unit transmits header information of the packet received by the packet receiving unit as a part of a packet for controlling a call connection between terminal apparatuses. The call connection between the terminal devices is monitored, and only immediately after the call connection is started, the short packet assembling means is sent to the short packet assembling means using a redundant packet consisting of header information of the packet received by the packet receiving means. 14. The packet transmission apparatus according to claim 13, further comprising connection / redundant packet control means for controlling the assembly.   When the data included in the packet received by the packet receiving means is silent audio data, the redundant packet comprising the header information of the packet received by the packet receiving means is used. 14. The packet transmission apparatus according to claim 13, further comprising redundant packet control means for controlling to assemble a short packet. Redundant packets are assembled in different packet formats corresponding to the data types from the redundant data of the packets transmitted to the destination terminal device, and the short packets assembled using the assembled redundant packets are multiplexed. Multiplexed packet receiving / decomposing means for receiving the multiplexed packet and decomposing the received multiplexed packet into individual short packets;
The short packet decomposed by the multiplexed packet receiving / decomposing means is divided into redundant packets and other information, and the data type is determined based on the packet format of the divided redundant packets, and based on the determination result Redundant packet replacement means for restoring a packet transmitted from the redundant packet to the original destination terminal device,
Packet assembling means for assembling a packet to be transmitted to the terminal device of the original destination from the information of the short packet divided by the redundant packet replacement means as information other than the redundant packet;
Terminal packet storage means for storing packets transmitted to the destination terminal device obtained by the redundant packet replacement means and the packet assembly means;
A packet transmission apparatus comprising: packet transmission means for transmitting packets stored in the terminal packet storage means to the destination terminal apparatus.

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