JP5066064B2 - Transmitting terminal, receiving terminal and transmission system used in one-way transmission path - Google Patents

Description

  The present invention relates to a header compression method for compressing IP header information by replacing IP header information with a context identifier (CID), and in particular, correspondence between CID and IP header information in a one-way transmission path from a transmission terminal to a reception terminal. The present invention relates to a technique for ensuring consistency between a transmission terminal and a reception terminal regarding the relationship.

  2. Description of the Related Art Conventionally, in a transmission system that transmits and receives IP packets, when transmitting an IP packet, a method of compressing the header of the IP packet and transmitting a compressed header packet to which a compressed header including only a part of the CID and the header is transmitted is known. (See Non-Patent Document 1). In this system, instead of transmitting all packets with all headers, compressed header packets are transmitted to improve transmission efficiency in the transmission system. Here, the CID is information for specifying an IP data flow of a packet to be subjected to header compression.

  FIG. 18 is a diagram for explaining a header compression method using a full header packet, a compressed header packet, and a CID table. In this header compression method, a transmission terminal inputs an IP packet to be transmitted, specifies a CID based on an IP header and a UDP header added to the IP packet, and generates a CID table including the CID and header information. The transmitting terminal intermittently transmits a full header packet with a header including a CID, an IP header, and a UDP header, and transmits a compressed header packet with a compressed header including a CID at other times.

  When receiving the full header packet, the receiving terminal stores the association between the CID included in the header of the full header packet, the IP header, and the UDP header in the CID table. Then, the receiving terminal continues to receive the compressed header packet, searches the CID table based on the CID included in the header of the compressed header packet, acquires header information associated with the CID, and uses the CID as the original IP header. And restore to UDP header. Then, the receiving terminal generates and outputs an IP packet.

  As described above, in the header compression method shown in FIG. 18, a CID table in which CIDs and header information are associated in advance is shared between the transmission terminal and the reception terminal, and the transmission terminal to the reception terminal is fully A header packet and a compressed header packet are transmitted. Thereby, all the header information can be shared between the transmitting terminal and the receiving terminal using the CID as a key.

  In such a header compression method, a technique that focuses on various problems is known (see, for example, Patent Documents 1 to 3). Patent Document 1 describes a technique for limiting the interval at which full header packets are transmitted in order to suppress a decrease in header compression efficiency and packet transmission efficiency.

  Further, in Patent Document 2, in order to reduce the number of compressed header packets discarded due to loss of full header packets or compressed header packets, the compressed header packets after loss are held, and based on the received full header packets. A technique for restoring the stored compressed header packet is described.

  Further, in Patent Document 3, in order to shorten a period of data loss, when an error is detected continuously in a received full header packet or a compressed header packet, the receiving terminal transmits a full header packet. A technique for requesting a transmission terminal to update a CID table is described.

  In a transmission system using such a header compression method, when transmitting a compressed header packet, the transmitting terminal transmits a full header packet in advance, thereby maintaining a common CID table between the transmitting terminal and the receiving terminal. can do. In the conventional header compression method, compression of the IP header in the IPv4 or IPv6 version is performed.

  FIG. 19 is a diagram showing the configuration of the CID table. (1) is a CID table when the IP header is IPv4, and (2) is a CID table when the IP header is IPv6. In (1), the IPv4 CID table includes a CID, an IPv4 header, and a UDP header. The IPv4 header includes a version indicating the version of the IP header, IHL (Internet Header Length), TOS (Type Of Service: service type), IP-ID (IP-Identification: IP identification number), Flg (Flag), Fragment Offset (fragment offset), TTL (Time To Live), Protocol (protocol), SrcAddr (source IP address), and DstAddr (destination IP address). The UDP header is composed of SrcPort (source port number) and DstPort (destination port number). In addition to the above, the IPv4 header has Total Length (packet length) and Header Checksum (header checksum), and the UDP header has Length (payload length) and Checksum (checksum) in addition to the above. Since these values are assumed to be different for each packet, they are not held in the CID table.

  In (2), the IPv6 CID table includes a CID, an IPv6 header, and a UDP header. The IPv6 header includes a version (version), a traffic class (traffic class), a flow label (flow label), a next header (next header), a hop limit (hop limit), and a srcAddr (source IP address) indicating the version of the IP header. And DstAddr (destination IP address). The UDP header is composed of SrcPort (source port number) and DstPort (destination port number). In addition to the above, the IPv6 header has a payload length (payload length), and the UDP header has a length (payload length) and a checksum (checksum) in addition to the above. Since they are assumed to be different, they are not held in the CID table.

  FIG. 20 is a diagram illustrating configurations of a full header packet and a compressed header packet. (1) shows the configuration of an IPv4 full header packet, (2) shows the configuration of an IPv4 compressed header packet, (3) shows the configuration of an IPv6 full header packet, and (4) 3 shows the structure of an IPv6 compressed header packet. The numbers indicate the byte length of each data item (the same applies to FIGS. 4 to 7, 21, 22, and 23).

  In (1), an IPv4 full header packet includes a CID, an SN (sequence number) indicating the order of packets having the same CID, a CID_header_type (CID header type: 0x20) indicating a header information type, IPv4_header_wo_length, UDP_header_wo_length and data. Consists of bytes.

  In (2), the compressed header packet of IPv4 includes a CID, SN (sequence number) indicating the order of packets having the same CID, CID_header_type (CID header type: 0x21), and identification (identification) indicating the identification number of the IPv4 header. ID number) and data bytes.

  In (3), the IPv6 full header packet is composed of CID, SN (sequence number) indicating the order of packets having the same CID, CID_header_type (CID header type: 0x60), IPv6_header_wo_length, UDP_header_wo_length, and data bytes. The

  In (4), the IPv6 compressed header packet is composed of a CID, an SN (sequence number) indicating the order of packets having the same CID, a CID_header_type (CID header type: 0x61), and a data byte.

  (1) to (4) are distinguished by CID_header_type (CID header type) in the full header packet and the compressed header packet. Further, IPv4_header_wo_length and UDP_header_wo_length in the IPv4 full header packet according to (1) respectively correspond to the IPv4 header and the UDP header in the IPv4 CID table shown in FIG. 19 (1). Further, IPv6_header_wo_length and UDP_header_wo_length in the IPv6 full header packet according to (3) correspond to the IPv6 header and the UDP header in the IPv6 CID table shown in FIG. 19 (2), respectively.

  FIG. 21 is a diagram illustrating a configuration of IPv4_header_wo_length in the IPv4 full header packet illustrated in FIG. This IPv4_header_wo_length is a version (version) indicating the version of the IP packet, IHL, TOS (Type Of Service: service type), IP-ID (IP-Identification: IP identification number), Flag (flag), Fragment Offset (fragment offset) ), TTL (Time To Live), Protocol (protocol), SrcAddr (source IP address) and DstAddr (destination IP address).

  FIG. 22 is a diagram showing a configuration of IPv6_header_wo_length in the IPv6 full header packet shown in FIG. 20 (3). This IPv6_header_wo_length is a version (version) indicating the version of the IP packet, a traffic class (traffic class), a flow label (flow label), a next header (next header), a hop limit (hop limit), and a srcAddr (source IP address). And DstAddr (destination IP address).

  FIG. 23 is a diagram showing a configuration of UDP_header_wo_length in the IPv4 and 6 full header packets shown in FIGS. 20 (1) and (3). This UDP_header_wo_length is composed of SrcPort (source port number) and DstPort (destination port number). For details of the configuration shown in FIGS. 20 to 23, refer to Non-Patent Document 1.

"Information and Communication Council, Information and Communication Technology Subcommittee (60th) Report of the 60-1-2 Broadcasting System Committee", [online], July 29, 2008, Information and Communication Council, [November 2008] Search on May 12], Internet <URL: http://www.soumu.go.jp/joho_tsusin/policyreports/joho_tsusin/bunkakai/080729_1.html> Japanese Patent No. 3234483 Japanese Patent No. 3730835 Japanese Patent No. 3323484

  By the way, in a bidirectional transmission path using an IP telephone or the like, when IP header information is compressed and transmitted, the header information is associated with the CID by negotiating between the transmitting terminal and the receiving terminal at the start of communication. be able to. Specifically, the transmitting terminal notifies the receiving terminal of a CID used for compressing header information of a packet to be transmitted. The receiving terminal receives the notification of the CID from the transmitting terminal, and updates the association data (hereinafter referred to as a CID record) between the held CID and the header information. Thereby, it is possible to prevent the CID from being associated with unintended header information in the receiving terminal.

  On the other hand, in a unidirectional transmission path such as a broadcast transmission path, the receiving terminal may start the receiving process at an arbitrary timing and end the receiving process at an arbitrary timing. Can not know the behavior of the receiving terminal. For this reason, the CID record held by the receiving terminal may be different from the CID record held by the sending terminal, and there is a mismatch between the sending terminal and the receiving terminal regarding the association between the CID and the header information. It can happen. Here, inconsistency means that the header information indicated by the CID in the CID record of the transmitting terminal does not match the header information indicated by the CID in the CID record of the receiving terminal. In this case, the receiving terminal receives a compressed header packet including a CID associated with certain header information, and restores the CID of the compressed header packet to other incorrect header information. That is, in the receiving terminal on the one-way transmission path, the association between the CID and the header information is not always correct.

  Accordingly, the present invention has been made to solve the above-described problems, and the object of the present invention is to provide a correspondence relationship between CID and header information when a compressed header packet in which header information is compressed is transmitted via a one-way transmission path. It is an object of the present invention to provide a transmission terminal, a reception terminal, and a transmission system that can avoid the mismatch.

  In order to solve the above-mentioned problem, when transmitting a set of a plurality of IP packets for each IP data flow, a transmission terminal according to the present invention uses the IP data flow as the header information of IP packets constituting the IP data flow. A CID table composed of a CID record including CID and header information in a transmission terminal that transmits a compressed header packet including the CID by replacing the header with a context identifier (CID) for identification, and the IP data flow CID is determined based on the header information of the IP packet constituting the CID, a CID record including the CID and header information is generated and written to the CID table, a compressed header packet including the CID is generated, and the IP Generation of all compressed header packets that make up the data flow After completion, a compressed header packet generation unit that deletes the CID record from the CID table, and a CID record that includes a CID and header information based on the CID table, is provided in the CID table provided on the side that receives the packet. A CID record update packet for writing and a CID record indicated by the CID are generated by the control packet generator and a control packet generator for generating a CID record deletion packet for deleting from the CID table provided on the receiving side. A transmission control unit that transmits the compressed header packet generated by the compressed header packet generation unit after transmitting the generated CID record update packet, and then transmits the CID record deletion packet generated by the control packet generation unit And provided that And butterflies.

  The transmitting terminal according to the present invention, when transmitting a set of a plurality of IP packets for each IP data flow, uses header information of the IP packet constituting the IP data flow as a context for specifying the IP data flow. In a transmitting terminal that replaces an identifier (CID) and compresses a header and transmits a compressed header packet including the CID, a CID table including a CID record including a CID and header information, and an IP packet constituting the IP data flow CID is determined based on the header information, and a CID record including the CID and header information is generated and added to the CID table, a full header packet including the CID and header information is generated, and from the CID table Read CID and generate compressed header packet Further, after the generation of all the compressed header packets constituting the IP data flow is completed, a full header packet / compressed header packet generation unit that deletes the CID record from the CID table, and a CID based on the CID table. The control packet generator for generating a CID record deletion packet for deleting the CID record indicated by the receiver from the CID table provided on the receiving side, and the full header packet generated by the full header packet / compressed header packet generator A transmission control unit that transmits a compressed header packet after transmission and then transmits a CID record deletion packet generated by the control packet generation unit.

  Further, in the transmission terminal according to the present invention, the control packet generation unit deletes all CID records from the CID table provided on the receiving side instead of the CID record deletion packet for deleting the CID record indicated by the CID. A CID record deletion packet is generated, and the transmission control unit transmits a CID record update packet after transmitting the CID record deletion packet generated by the control packet generation unit, and then generated by the compressed header packet generation unit. The compressed header packet is transmitted.

  The transmitting terminal according to the present invention is characterized in that the CID record deletion packet is a packet for deleting a CID record that is not stored in the CID table of the transmitting terminal.

  The transmitting terminal according to the present invention, when transmitting a set of a plurality of IP packets for each IP data flow, uses header information of the IP packet constituting the IP data flow as a context for specifying the IP data flow. In a transmitting terminal that replaces an identifier (CID) and compresses a header and transmits a compressed header packet including the CID, a CID table including a CID record including a CID and header information, and an IP packet constituting the IP data flow CID is determined on the basis of the header information, and a CID record including the CID and header information is generated and written to the CID table, a compressed header packet including the CID is generated, and the IP data flow is configured. After generation of all compressed header packets is complete, A compressed header packet generation unit that deletes a CID record from the CID table, and a correspondence relationship between a transmission source address and a destination address of the packet and a CID is described based on the CID table, and is provided on the side that receives the packet. A transmission control signal generation unit that generates a transmission control signal used to update a CID record in the CID table, and a transmission control signal generated by the transmission control signal generation unit, and then the compressed header packet The compressed header packet generated by the generation unit is transmitted.

  In addition, the receiving terminal according to the present invention performs header compression by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow, and the compressed header with the header compressed. In the receiving terminal that receives the packet, a CID table composed of a CID record including CID and header information, a CID record update packet for adding the compressed header packet, CID and header information to the CID table, and CID A reception control unit that receives a CID record deletion packet for deleting the CID record or all CID records from the CID table and distinguishes the received packet, and a CID record update packet distinguished by the reception control unit The above A CID record including the CID and header information of the ID record update packet is added to the CID table, and for the CID record deletion packet distinguished by the reception control unit, the CID record indicated by the CID of the CID record deletion packet or all The header information is read from the CID table using the CID of the compressed header packet for the compressed header packet distinguished by the control packet processing unit that deletes the CID record from the CID table and the reception control unit, and the IP And a compressed header packet processing unit that generates an IP packet constituting the data flow.

  In addition, the receiving terminal according to the present invention performs header compression by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow, and the compressed header with the header compressed. In a receiving terminal that receives a packet, a CID table configured from a CID record including CID and header information, a full header packet including the compressed header packet, CID and header information, and a CID record indicated by the CID are stored in the CID table. CID record for deleting the packet from the reception control unit for distinguishing these packets, and the CID record including the CID of the full header packet and the header information for the full header packet distinguished by the reception control unit C D data is written to the D table, and an IP packet constituting an IP data flow is generated from the full header packet, and a header from the CID table is used for the compressed header packet distinguished by the reception control unit using the CID of the compressed header packet. The CID record indicated by the CID of the CID record deletion packet for the compressed header packet processing unit that reads the information and generates the IP packet constituting the IP data flow, and the CID record deletion packet distinguished by the reception control unit, And a control packet processing unit to be deleted from the CID table.

  In addition, the receiving terminal according to the present invention performs header compression by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow, and the compressed header with the header compressed. In the receiving terminal that receives the packet, the CID table composed of the CID record including the CID and the header information, and the correspondence between the source address and the destination address of the IP packet constituting the IP data flow and the CID are described. The transmission control signal and the reception control unit that receives the compressed header packet and distinguishes these signals and packets, and the transmission control signal distinguished by the reception control unit includes the CID and header information of the transmission control signal. Update the CID table with the CID record For the compressed header packet distinguished by the transmission control signal processing unit and the reception control unit, the header information is read from the CID table using the CID of the compressed header packet, and the IP packet constituting the IP data flow is generated. And a compressed header packet processing unit.

  The transmission system according to the present invention is characterized by comprising the transmitting terminal and the receiving terminal.

  As described above, the CID table of the receiving terminal matches the CID table provided in the transmitting terminal with respect to the correspondence relationship between the CID and the header information. Therefore, when the compressed header packet is received via the one-way transmission path, Header information is not restored. Therefore, it is possible to avoid inconsistency in the correspondence between the CID and the header information.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
First, a transmission system using a transmission terminal and a reception terminal according to an embodiment of the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of the transmission system. This transmission system is a satellite broadcasting system that realizes advanced BS digital broadcasting, and includes a file transmission device and a multiplexing device (transmission terminal 1) provided in a broadcasting station, and an advanced BS tuner (for example, installed in a general home). A receiving terminal 2) and a network terminal device are provided. The transmission terminal 1 and the reception terminal 2 are connected by a unidirectional transmission path 3 which is a broadcast transmission path via a broadcasting satellite.

  The transmission terminal 1 multiplexes the IP packet input from the file transmission device, and transmits the broadcast wave to the reception terminal 2 via the one-way transmission path 3. Specifically, the transmission terminal 1 generates a TLV (Type Length Value) including information for realizing a television broadcast service and content for realizing a content load service, and transmits the TLV as a broadcast wave. At this time, the IP packet of the content to be distributed, an address map table (AMT) as a transmission control signal, and the like are stored in the TLV. TLV and AMT will be described later.

  The receiving terminal 2 receives a broadcast wave from the transmitting terminal 1 via the unidirectional transmission path 3, acquires an IP packet from the received broadcast wave, and outputs it to the network terminal device via the home network. In this way, the network terminal device in a general home can be requested by the operator from the file transmission device provided in the broadcasting station via the transmission terminal 1, the one-way transmission path 3 and the reception terminal 2 by the download application. The content can be viewed or recorded by receiving an IP packet of the content to be played.

  In such a transmission system, as illustrated in FIG. 18, the transmission terminal 1 generates a compressed header packet from the input IP packet using a CID table, and transmits the generated compressed header packet to the reception terminal 2. . The receiving terminal 2 receives the compressed header packet, restores the CID included in the received compressed header packet to header information using the CID table, generates an IP packet, and outputs the IP packet.

  Hereinafter, a method in which the receiving terminal 2 restores the CID of the received compressed header packet to the correct header information using the CID table in which the correspondence between the CID and the header information is consistent with the transmitting terminal 1 will be described. The first embodiment updates the CID table by using control packets such as a CID record update packet and a CID record deletion packet. In the second embodiment, the CID table is updated by using an AMT that is a transmission control signal transmitted by a control type TLV container. The third embodiment uses a CID table that stores preset fixed CID and header information.

[Example 1]
First, Example 1 will be described. In the first embodiment, the CID table is updated using a control packet such as a CID record update packet and a CID record deletion packet, thereby avoiding inconsistency in the correspondence between the CID and the header information.

(Sending terminal)
The configuration of the transmission terminal will be described. FIG. 2 is a block diagram illustrating a configuration of the transmission terminal according to the first embodiment. The transmission terminal 1-1 includes a full header packet / compressed header packet generation unit 11, a control packet generation unit 12, a transmission control unit 13, and a CID table 10. The CID table 10 is stored in the storage means and has the same configuration as the CID table shown in FIG.

  The full header packet / compressed header packet generation unit 11 receives an IP packet, distinguishes the input plurality of IP packets based on information (IP header and UDP header) described in the header of the IP packet, and Identify the data flow. Here, the IP data flow has a unique combination of the values of the five fields of protocol type, transmission source IP address, destination IP address, transmission source port number, and destination port number included in the IP header and UDP header. It is a set of IP packets.

  Then, the full header packet / compressed header packet generation unit 11 determines a CID that can be assigned for each identified IP data flow, generates a CID record including various data of the CID, the IP header, and the UDP header. Save to. Further, the full header packet / compressed header packet generation unit 11 generates the full header packet and the compressed header packet shown in FIGS. 20 to 23 and outputs them to the transmission control unit 13. In Examples 1-1 and 1-3, which will be described later, only a compressed header packet is generated without generating a full header packet.

  The control packet generation unit 12 reads the CID record from the CID table 10, generates a control packet for the CID record update packet, the CID record deletion packet, and the CID record all deletion packet based on the content of the CID record, and the transmission control unit 13 Output to. In Example 1-1 to be described later, a CID record update packet and a CID record deletion packet are generated. In Example 1-2, only a CID record deletion packet is generated. In Example 1-3, all CIDs are generated. A CID record all deletion packet and a CID record update packet for deleting a record are generated.

  FIG. 4 is a diagram illustrating a configuration of a CID record update packet. As shown in FIG. 4 (1), the IPv4 CID record update packet is composed of CID, SN, CID_header_type (CID header type: 0x2F), IPv4_header_wo_length, and UDP_header_wo_length. Also, as shown in FIG. 4B, the IPv6 CID record update packet is composed of CID, SN, CID_header_type (CID header type: 0x6F), IPv6_header_wo_length, and UDP_header_wo_length. In the receiving terminal 2, the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length in the CID record update packet are stored in the CID table as a CID record including a CID, an IP header, and a UDP header. This CID record update packet has the same configuration as the full header of the IPv4 full header packet shown in FIG. 20 (1) and the full header of the IPv6 full header packet shown in FIG. 20 (3). Yes. That is, the CID record update packet is equivalent to a configuration in which the data byte area is removed from these full header packets.

  FIG. 5 is a diagram illustrating a configuration of a CID record deletion packet. As shown in FIG. 5, the CID record deletion packet is composed of CID, SN, and CID_header_type (CID header type: 0x80). In the receiving terminal 2, the CID record indicated by the CID of the CID record deletion packet is deleted from the CID table.

  FIG. 6 is a diagram illustrating a configuration of a CID record deletion packet for deleting a plurality of CID records. As shown in FIG. 6, the CID record deletion packet is composed of CID, SN, CID_header_type (CID header type: 0x80), and CID. In the receiving terminal 2, the CID records indicated by the plurality of CIDs in the CID record deletion packet are deleted from the CID table.

  FIG. 7 is a diagram showing a configuration of a CID record all deletion packet. As shown in FIG. 7, the CID record all deletion packet is composed of CID, SN, and CID_header_type (CID header type: 0x81). In the receiving terminal 2, all the CID records are deleted from the CID table by the CID record all deletion packet.

Table 1 shows assignment of CID_header_type (CID header type) in a full header packet, a compressed header packet, a CID record update packet, a CID record deletion packet, and a CID record all deletion packet. The CID header type has different values depending on IPv4 and IPv6 except for the CID record deletion packet and the CID record all deletion packet.

  Returning to FIG. 2, the transmission control unit 13 inputs the full header packet and the compressed header packet generated by the full header packet / compressed header packet generation unit 11, and the control packet ( CID record update packet, CID record delete packet, CID record all delete packet). Then, the transmission control unit 13 transmits each packet to the one-way transmission path 3 in accordance with a preset transmission order. Here, the packet is stored in the TLV and transmitted. The TLV includes a future reservation, a TLV packet type, a data length, and data fields, and actual information such as a packet and an AMT is stored in the data field. Refer to Non-Patent Document 1 for details of TLV.

(Receiving terminal)
Next, the configuration of the receiving terminal will be described. FIG. 3 is a block diagram illustrating the configuration of the receiving terminal according to the first embodiment. The receiving terminal 2-1 includes a reception control unit 21, a control packet processing unit 22, a full header packet processing unit 23, a compressed header packet processing unit 24, and a CID table 20. The CID table 20 is stored in the storage means and has the same configuration as the CID table shown in FIG.

  The reception control unit 21 receives a packet from the one-way transmission path 3 and distinguishes it into a full header packet, a compressed header packet, and a control packet based on CID_header_type (CID header type). The reception control unit 21 outputs the full header packet to the full header packet processing unit 23, the compressed header packet to the compressed header packet processing unit 24, and the control packet to the control packet processing unit 22. Here, since the reception control unit 21 receives the TLV storing the packet, the reception control unit 21 performs processing for recognizing and extracting the packet from the TLV. The TLV also includes a transmission control signal such as AMT, and performs processing according to each information.

  The full header packet processing unit 23 receives the full header packet from the reception control unit 21, extracts the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the full header packet, generates a CID record including the CID, IP header, and UDP header. Save in table 20. Then, the full header packet processing unit 23 removes the CID, SN, and CID_header_type (CID header type) from the full header packet, adds the length calculated from the “data length” field of the TLV, and further calculates the checksum. The IP packet is generated and output.

  The compressed header packet processing unit 24 inputs the compressed header packet from the reception control unit 21, extracts the CID that is the compressed header from the compressed header packet, searches the CID table 20 using the CID as a key, and searches for CID records having the same CID. Read IP header and UDP header. Then, the compressed header packet processing unit 24 removes the CID, SN, and CID_header_type (CID header type) from the compressed header packet, adds the length calculated from the “data length” field of the TLV, and further calculates the checksum. The IP packet is generated and output. The full header packet processing unit 23 and the compressed header packet processing unit 24 output IP packets in the order according to the SNs of the full header packet and the compressed header packet.

  The control packet processing unit 22 receives a control packet from the reception control unit 21 and distinguishes it into a CID record update packet, a CID record deletion packet, and a CID record all deletion packet based on the CID_header_type (CID header type) shown in Table 1. To do.

  Then, when the input packet is a CID record update packet, the control packet processing unit 22 extracts CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the CID record update packet, and generates a CID record including a CID, an IP header, and a UDP header, Save to the CID record 20. When the input packet is a CID record deletion packet, the control packet processing unit 22 extracts the CID from the CID record deletion packet and deletes the CID record indicated by the CID from the CID table 20. Furthermore, when the input packet is a CID record all deletion packet, the control packet processing unit 22 deletes all CID records from the CID table 20.

Next, a specific embodiment using the above-described control packet by the transmitting terminal 1-1 shown in FIG. 2 and the receiving terminal 2-1 shown in FIG. 3 will be described.
[Example 1-1]
First, Example 1-1 will be described. This Example 1-1 uses the CID record update packet and the CID record deletion packet without using the full header packet, thereby causing inconsistency between the transmitting terminal and the receiving terminal regarding the correspondence between the CID and the header information. To avoid.

  FIG. 8 is a diagram illustrating the transmission order of the CID record update packet, the CID record deletion packet, and the compressed header packet according to Example 1-1. As shown in FIG. 8, when transmitting the same file, a CID record update packet, a compressed header packet, and a CID record deletion packet are transmitted in this order.

  This will be specifically described below. First, the process of the transmission terminal 1-1 will be described. When the full header packet / compressed header packet generation unit 11 of the transmission terminal 1-1 receives the IP packet of the file 1, the IP data flow is specified to determine the CID, and the CID record including the CID, the IP header, and the UDP header Is newly generated and stored in the CID table 10. Then, the full header packet / compressed header packet generator 11 generates the compressed header packet shown in FIG. 20 from the input IP packet.

  On the other hand, the control packet generator 12 reads the CID record newly stored by the full header packet / compressed header packet generator 11 from the CID table 10 and generates the CID record update packet shown in FIG. In this case, the control packet generator 12 sets the CID, IP header, and UDP header of the read CID record to the CID of the CID record update packet, IPv4_header_wo_length, and UDP_header_wo_length, respectively, and the full header packet / compressed header packet generator 11 CID_header_type (CID header type) is set according to the protocol type of the identified IP data flow.

  The transmission control unit 13 inputs the compressed header packet generated by the full header packet / compressed header packet generation unit 11 and the CID record update packet generated by the control packet generation unit 12. Then, the transmission control unit 13 transmits a CID record update packet before transmitting the compressed header packet. Thereby, the receiving terminal 2-1 can acquire the CID and header information that are consistent with the transmitting terminal 1-1 using the CID record update packet. The transmission control unit 13 transmits the compressed header packet after transmitting the CID record update packet. A sequence number is set in the SN of the transmitted packet.

  The full header packet / compressed header packet generation unit 11 deletes the stored CID record from the CID table 10 when the generation of all the compressed header packets for the input IP packet of the file 1 is completed.

  On the other hand, the control packet generator 12 recognizes that the CID record has been deleted by referring to the CID table 10, and generates a CID record deletion packet including the CID of the deleted CID record as shown in FIG. To do.

  When the transmission control unit 13 inputs the CID record deletion packet generated by the control packet generation unit 12 and completes transmission of all the compressed header packets generated by the full header packet / compression header packet generation unit 11, the CID record Send a delete packet.

  When the file 2 is subsequently transmitted, the same processing as that for transmitting the file 1 is performed. Note that when the file 1 and the file 2 are transmitted with the same header information, the same CID can be used. For this reason, the transmission control unit 13 does not need to transmit the CID record deletion packet related to the transmission of the file 1 and the CID record update packet related to the transmission of the file 2 after transmitting the compressed header packet constituting the file 1. That is, the transmission control unit 13 transmits the compressed header packet configuring the file 2 after transmitting the compressed header packet configuring the file 1, and transmits the CID record deletion packet after the transmission of the compressed header packet is completed. .

  Next, processing of the receiving terminal 2-1 will be described. When the reception control unit 21 of the reception terminal 2-1 receives the packet transmitted by the transmission terminal 1-1, the reception control unit 21 converts the packet into a CID record update packet, a compressed header packet, and a CID record deletion packet based on the CID_header_type (CID header type). Distinguish.

  The control packet processing unit 22 inputs the CID record update packet distinguished by the reception control unit 21, generates a CID record including a CID, an IP header, and a UDP header, and stores the CID record in the CID table 20.

  The compressed header packet processing unit 24 inputs the compressed header packet distinguished by the reception control unit 21, reads the IP header and UDP header from the CID table 20 using the CID as a key, generates and outputs an IP packet.

  Then, the control packet processing unit 22 inputs the CID record deletion packet distinguished by the reception control unit 21 and deletes the CID record indicated by the CID from the CID table 20.

  As described above, according to the embodiment 1-1, the transmission terminal 1-1 transmits in the order of the CID record update packet, the compressed header packet, and the CID record deletion packet, and the reception terminal 2-1 updates the CID record. A new CID record is stored in the CID table 20 by the packet, and after the reception process of the compressed header packet is completed, the CID record is deleted from the CID table 20 by the CID record deletion packet. Thereby, the receiving terminal 2-1 receives the CID record update packet including the CID used for transmission immediately after the CID record update packet and the header information, and the CID matching the transmission terminal 1-1 with respect to the relationship between the CID and the header information. Since the record is stored in the CID table 20, inconsistency in the correspondence between the CID and the header information can be avoided. Also, when receiving the compressed header packet, the receiving terminal 2-1 restores the CID to the header information by the CID table 20 including the CID matched with the transmitting terminal 1-1 and the CID record of the header information. The compressed header is not restored to incorrect header information.

  In the example 1-1, the transmission terminal 1-1 may transmit the CID record update packet of the file 2 at the time of the transmission process of the file 1 or before that. Thus, prior to the file 2 transmission process, a CID record for transmitting the file 2 can be secured in the CID tables 10 and 20 in advance.

[Example 1-2]
Next, Example 1-2 will be described. In this embodiment 1-2, by using a full header packet and a CID record deletion packet without using a CID record update packet, the correspondence between the CID and the header information is inconsistent between the transmitting terminal and the receiving terminal. To avoid.

  FIG. 9 is a diagram illustrating the transmission order of the CID record deletion packet, the full header packet, and the compressed header packet according to the embodiment 1-2. As shown in FIG. 9, when transmitting the same file, a full header packet, a compressed header packet, and a CID record deletion packet are transmitted in this order. The full header packet is transmitted every time a certain amount of compressed header packets are transmitted.

  This will be specifically described below. First, the process of the transmission terminal 1-1 will be described. When the full header packet / compressed header packet generation unit 11 of the transmission terminal 1-1 receives the IP packet of the file 1, the IP data flow is specified to determine the CID, and the CID record including the CID, the IP header, and the UDP header Is newly generated and stored in the CID table 10. Then, the full header packet / compressed header packet generator 11 generates the full header packet and the compressed header packet shown in FIG. 20 from the input IP packet. In this case, the full header packet is generated so as to be transmitted each time a certain amount of compressed header packet is transmitted.

  The transmission controller 13 receives the full header packet and the compressed header packet generated by the full header packet / compressed header packet generator 11 and transmits them in the order shown in FIG. Thereby, the receiving terminal 2-1 can acquire CID and header information matched with the transmitting terminal 1-1 using a full header packet.

  The full header packet / compressed header packet generation unit 11 deletes the stored CID record from the CID table 10 when the generation of all full header packets and compressed header packets for the input IP packet of the file 1 is completed.

  On the other hand, the control packet generator 12 recognizes that the CID record has been deleted by referring to the CID table 10, and generates a CID record deletion packet including the CID of the deleted CID record as shown in FIG. To do.

  The transmission control unit 13 inputs the CID record deletion packet generated by the control packet generation unit 12, and completes transmission of all full header packets and compressed header packets generated by the full header packet / compressed header packet generation unit 11. Then, the CID record deletion packet generated by the control packet generator 12 is transmitted.

  When the file 2 is subsequently transmitted, the same processing as that for transmitting the file 1 is performed. Note that when the file 1 and the file 2 are transmitted with the same header information, the same CID can be used. For this reason, the transmission control unit 13 does not need to transmit the CID record deletion packet after transmitting the full header packet and the compressed header packet constituting the file 1. That is, the transmission control unit 13 transmits the full header packet and the compressed header packet that configure the file 2 after transmitting the full header packet and the compressed header packet that configure the file 1, and after the transmission of the compressed header packet is completed. A CID record deletion packet is transmitted.

  Next, processing of the receiving terminal 2-1 will be described. When receiving the packet transmitted by the transmitting terminal 1-1, the receiving control unit 21 of the receiving terminal 2-1 distinguishes between a full header packet, a compressed header packet, and a CID record deletion packet based on the CID_header_type (CID header type). To do.

  The full header packet processing unit 23 receives the full header packet distinguished by the reception control unit 21, generates a CID record including a CID, an IP header, and a UDP header, and stores the CID record in the CID table 20. The full header packet processing unit 23 generates and outputs an IP packet.

  The compressed header packet processing unit 24 inputs the compressed header packet distinguished by the reception control unit 21, reads the IP header and UDP header from the CID table 20 using the CID as a key, generates and outputs an IP packet.

  Then, the control packet processing unit 22 inputs the CID record deletion packet distinguished by the reception control unit 21 and deletes the CID record indicated by the CID from the CID table 20.

  As described above, according to the embodiment 1-2, the transmission terminal 1-1 transmits in the order of the full header packet, the compressed header packet, and the CID record deletion packet, and the reception terminal 2-1 uses the full header packet. A new CID record is stored in the CID table 20, and after the reception processing of all full header packets and compressed header packets is completed, the CID record is deleted from the CID table 20 by a CID record deletion packet. Thereby, the receiving terminal 2-1 receives the full header packet including the CID and the header information, and stores the CID record matched with the transmitting terminal 1-1 with respect to the relationship between the CID and the header information in the CID table 20. Inconsistency with the transmission terminal 1-1 can be avoided with respect to the correspondence between the CID and the header information. Also, when receiving the compressed header packet, the receiving terminal 2-1 restores the CID to the header information by the CID table 20 including the CID matched with the transmitting terminal 1-1 and the CID record of the header information. The compressed header is not restored to incorrect header information.

  In Examples 1-1 and 1-2, the control packet generation unit 12 of the transmission terminal 1-1 generates the CID record deletion packet illustrated in FIG. 5 in order to delete one CID record. However, in order to simultaneously delete a plurality of CID records, the CID record deletion packet shown in FIG. 6 may be generated. For example, the control packet generation unit 12 of the transmission terminal 1-1 stores a used CID, and specifies a used CID that is not stored in the CID table 10. Then, a CID record deletion packet is generated in order to delete the CID record of the specified CID from the CID table 20 of the receiving terminal 2-1. As a result, the receiving terminal 2-1 can delete not only the CID record after the use of a certain CID but also the CID record of the CID used immediately before or not used at the same time. . That is, a CID record that is not stored in the CID table 10 of the transmission terminal 1-1 can be deleted from the CID table 20 of the reception terminal 2-1.

  Further, in the embodiments 1-1 and 1-2, an example in which the files 1 and 2 are transmitted has been described. That is, at the timing when a new IP data flow is specified and the CID is switched, the CID record update packet is transmitted in the embodiment 1-1, and the full header packet is transmitted in the embodiment 1-2. When the streaming is completed, the CID record deletion packet is transmitted in the embodiments 1-1 and 1-2.

[Example 1-3]
Next, Example 1-3 will be described. The embodiment 1-3 avoids inconsistency between the transmission terminal and the reception terminal regarding the correspondence between the CID and the header information by using the CID record all deletion packet and the CID record update packet.

  FIG. 10 is a diagram illustrating the transmission order of the CID record all deletion packet, the CID record update packet, and the compressed header packet according to the embodiment 1-3. As shown in FIG. 10, when transmitting the same file, the CID record all deletion packet is transmitted in advance before the file transmission is performed, and the CID record update packet and the compressed header packet are transmitted in this order. The

  This will be specifically described below. First, the process of the transmission terminal 1-1 will be described. When the full header packet / compressed header packet generation unit 11 of the transmission terminal 1-1 receives the IP packet of the file 1, the IP data flow is specified to determine the CID, and the CID record including the CID, the IP header, and the UDP header Is newly generated and stored in the CID table 10. Then, the full header packet / compressed header packet generator 11 generates the compressed header packet shown in FIG. 20 from the input IP packet.

  On the other hand, the control packet generator 12 reads the CID record newly stored by the full header packet / compressed header packet generator 11 from the CID table 10 and generates the CID record update packet shown in FIG. At this time, a CID record all deletion packet is also generated.

  The transmission control unit 13 inputs the compressed header packet generated by the full header packet / compressed header packet generation unit 11 and the CID record all deletion packet and CID record update packet generated by the control packet generation unit 12. . Then, the transmission control unit 13 transmits a CID record all deletion packet prior to transmitting the CID record update packet and the compressed header packet. Thereby, the receiving terminal 2-1 can delete all the CID records from the CID table 20. Then, the transmission control unit 13 transmits a CID record update packet. Thereby, the receiving terminal 2-1 can store the same CID record as the transmitting terminal 1-1 in the CID table 20 using the CID record update packet. The transmission control unit 13 transmits the compressed header packet after transmitting the CID record update packet.

  The full header packet / compressed header packet generation unit 11 deletes the stored CID record from the CID table 10 when the generation of all the compressed header packets for the input IP packet of the file 1 is completed.

  Next, the receiving terminal 2-1 will be described. When the reception control unit 21 of the reception terminal 2-1 receives the packet transmitted by the transmission terminal 1-1, the CID record all deletion packet, the CID record update packet, and the compression header packet are received based on the CID_header_type (CID header type). Distinguish between

  The control packet processing unit 22 inputs the CID record all deletion packet distinguished by the reception control unit 21 and deletes all the CID records from the CID table 20.

  Then, the control packet processing unit 22 inputs the CID record update packet distinguished by the reception control unit 21, generates a CID record including a CID, an IP header, and a UDP header, and stores the CID record in the CID table 20.

  The compressed header packet processing unit 24 inputs the compressed header packet distinguished by the reception control unit 21, reads the IP header and the UDP header from the CID table 20 using the CID as a key, generates an IP packet, and outputs the IP packet.

  As described above, according to the embodiment 1-3, the transmission terminal 1-1 transmits the CID record all deletion packet, the CID record update packet, and the compressed header packet in this order, and the reception terminal 2-1 All CID records are deleted from the CID table 20 by the all deletion packet, and a new CID record is stored in the CID table 20 by the CID record update packet. As a result, the receiving terminal 2-1 clears the CID table 20 prior to file transmission, and then receives the CID record update packet including the CID and header information used for transmission immediately after the CID record update packet. Since the CID record matched with the transmission terminal 1-1 about the information relationship is preserve | saved in the CID table 20, the mismatch of the correspondence of CID and header information can be avoided. Also, when receiving the compressed header packet, the receiving terminal 2-1 restores the CID to the header information by the CID table 20 including the CID matched with the transmitting terminal 1-1 and the CID record of the header information. The compressed header is not restored to incorrect header information.

[Example 2]
Next, Example 2 will be described. The second embodiment avoids inconsistency between the transmission terminal and the reception terminal regarding the correspondence between the CID and the header information by updating the CID table using the AMT that is the transmission control signal.

(Sending terminal)
First, the configuration and processing of the transmission terminal will be described. FIG. 11 is a block diagram illustrating a configuration of the transmission terminal according to the second embodiment. The transmission terminal 1-2 includes a compressed header packet generation unit 14, an AMT generation unit 15, a transmission control unit 16, and a CID table 10. The CID table 10 is stored in the storage means and has the same configuration as the CID table shown in FIG.

  The compressed header packet generation unit 14 receives an IP packet, distinguishes a plurality of input IP packets based on information (IP header and UDP header) described in the IP packet header, and specifies an IP data flow To do. Then, the compressed header packet generation unit 14 determines a CID that can be assigned for each identified IP data flow, generates a CID record including various data of the CID, the IP header, and the UDP header, and stores the CID record in the CID table 10. Further, the compressed header packet generator 14 generates the compressed header packet shown in FIG. 20 and outputs it to the transmission controller 16.

  The AMT generation unit 15 reads all CID records from the CID table 10 and adds each CID to the AMT that has already been generated prior to file transmission.

  FIG. 13 is a diagram illustrating the configuration of the AMT used in the second embodiment. This AMT is a table that associates a multicast group of an IP packet with a service ID (service identifier). As shown in FIG. 13, in addition to the service ID (service_id) and the IP version (ip_ver), the AMT includes src_addr and src_mask indicating the range of the source IP address, dst_addr and dst_mask indicating the range of the destination IP address, and It consists of a CID associated with these data. src_mask is information indicating how many bits are identified from the head of the IP address described as src_addr. Also, dst_mask is information indicating how many bits from the beginning of the IP address described as dst_addr are identified.

  AMT is one of transmission control signals transmitted to all receiving terminals using a control type TLV container in a satellite broadcasting system that realizes advanced BS digital broadcasting. Therefore, the AMT is essentially composed of data obtained by removing the CID from the configuration shown in FIG. In the second embodiment, as shown in FIG. 13, CID is added to these data.

  More specifically, the AMT generation unit 15 reads all CID records from the CID table 10, the source IP address (SrcAddr) and the destination IP address (DstAddr) of which are already generated prior to file transmission. The AMT record that matches the source IP address (src_addr) and the destination IP address (dst_addr) of the existing AMT is specified, and the CID of the read CID record is stored in the CID field of the record. The AMT generated in this way is output to the transmission control unit 16. The AMT generation unit 15 performs the above-described process at a predetermined time interval and outputs the AMT to the transmission control unit 16.

  Returning to FIG. 11, the transmission control unit 16 inputs the compressed header packet generated by the compressed header packet generation unit 14 and the AMT generated by the AMT generation unit 15. Then, prior to transmission of the compressed header packet, the transmission control unit 16 stores and transmits the AMT including the CID of the compressed header packet in the TLV (control TLV). And the transmission control part 16 stores a compression header packet in TLV, and transmits. The transmission control unit 16 periodically stores the AMT input from the AMT generation unit 15 in the TLV (control TLV) and transmits the AMT.

  FIG. 14 is a diagram illustrating the transmission order when the CID table is updated by AMT in the second embodiment. The AMT is periodically stored in the TLV and transmitted, and transmitted before the compressed header packet is transmitted. As shown in FIG. 14, the compressed header packet of file 1 is transmitted and the compressed header packet of file 2 is transmitted under the situation where the CID table 20 is updated at the receiving terminal.

(Receiving terminal)
Next, the configuration and processing of the receiving terminal will be described. FIG. 12 is a block diagram illustrating a configuration of a receiving terminal according to the second embodiment. The reception terminal 2-2 includes a reception control unit 25, an AMT processing unit 26, a compressed header packet processing unit 27, and a CID table 20. The CID table 20 is stored in the storage means and has the same configuration as the CID table shown in FIG.

  The reception control unit 25 receives the TLV from the one-way transmission path 3, extracts the packet, AMT, and the like from the TLV, and distinguishes the packet into a compressed header packet based on CID_header_type (CID header type). Then, the reception control unit 25 outputs the distinguished compressed header packet to the compressed header packet processing unit 27. Further, the reception control unit 25 outputs the AMT to the AMT processing unit 26.

  The AMT processing unit 26 receives the AMT from the reception control unit 25, extracts all CIDs, ip_ver, src_addr, and dst_addr from the AMT, and sets them in the CID, Version, SrcAddr, and DstAddr in the CID record. Then, data constituting the CID record other than these data is fixed (using preset data), a CID record is generated, and stored in the CID table 20. Here, the AMT has fields for storing CID, ip_ver, src_addr (source IP address), and dst_addr (destination IP address), and the source port number (SrcPort) and destination port number (DstPort) to be stored in the CID record. ) Etc. are not included. However, in the one-way transmission path 3, there is no problem even if the protocol type is UDP and operation is restricted, and data such as the source port number (SrcPort) and the destination port number (DstPort) should be set in advance by the application. In commercial services, these values can be used fixedly. Therefore, the AMT processing unit 26 sets the CID, Version, SrcAddr, and DstAddr extracted from the AMT as they are, and generates a CID record by setting the data constituting the CID record other than these data as fixed. And stored in the CID table 20. In this case, the AMT processing unit 26 deletes all the CID records in the CID table 20 and then stores all the generated CID records in the CID table 20.

  The compressed header packet processing unit 27 inputs the compressed header packet from the reception control unit 25, extracts the CID that is the compressed header from the compressed header packet, searches the CID table 20 using the CID as a key, and searches for CID records having the same CID. Read IP header and UDP header. Then, the compressed header packet processing unit 27 generates and outputs an IP packet.

  Thus, as shown in FIG. 13, the AMT generating unit 15 of the transmitting terminal 1-2 adds the CID to the original AMT and transmits it, so that the receiving terminal 2-2 that has received this transmits the service. It is possible to specify the multicast group, that is, the CID of the IP packet to be configured. Further, the receiving terminal 2-2 can specify the multicast group of the IP packet from the CID.

  As described above, according to the second embodiment, the transmission terminal 1-2 transmits the AMT with the CID added before transmitting the compressed header packet using the CID, and the reception terminal 2-2 transmits the AMT. The CID table 20 is cleared each time it is received, and a new CID record is stored in the CID table 20 using AMT data and preset data. Thereby, whenever receiving terminal 2-2 receives AMT including a part of CID and header information, it can make up for missing header information by using fixed data, and can update CID table 20. Therefore, inconsistency with the transmission terminal 1-2 regarding the correspondence between the CID and the header information can be avoided. When receiving the compressed header packet, the receiving terminal 2-2 restores the CID to the header information by the CID table 20 including the CID matched with the transmitting terminal 1-2 and the CID record of the header information. The compressed header is not restored to incorrect header information.

Example 3
Next, Example 3 will be described. In the third embodiment, by using a CID table in which a fixed CID and header information that are set in advance are stored, inconsistency occurs between the transmission terminal and the reception terminal regarding the correspondence between the CID and the header information. To avoid. In the first and second embodiments, a CID is arbitrarily assigned to five pieces of information (protocol type, source IP address, destination IP address, source port number, and destination port number) for specifying an IP data flow. Can do. That is, even for the same IP data flow, different CIDs may be assigned if the date and time are different, and even if the same CID is assigned to different IP data flows if the date and time are different. On the other hand, in the third embodiment, the same CID is always assigned to the same IP data flow, and the same CID is always assigned to the same IP data flow according to the time. It is.

(Sending terminal)
First, the configuration and processing of the transmission terminal will be described. FIG. 15 is a block diagram illustrating a configuration of the transmission terminal according to the third embodiment. The transmission terminal 1-3 includes a compressed header packet generation unit 17, a transmission control unit 18, a CID table management unit 19, a CID table 10, and a flow / time-specific CID allocation table 40. The CID table 10 is stored in the storage means and has the same configuration as the CID table shown in FIG. The flow / time-specific CID allocation table 40 is stored in a storage medium such as a non-volatile memory as a storage means.

  When the CID table management unit 19 inputs time information from a timer (not shown) and determines that the predetermined time has been reached, the CID and IP data flow data corresponding to the predetermined time are determined from the flow / time-specific CID allocation table 40. After reading (protocol type, source IP address, destination IP address, source port number and destination port number), generating a CID record consisting of various data of CID, IP header and UDP header, and clearing the CID table 10 The generated CID record is stored in the CID table 10.

  FIG. 17 is a diagram showing the configuration of the flow / time-specific CID allocation table 40. As shown in FIG. 17, the CID allocation table 40 for each flow / time includes the CID of the flow 1 and flow 2 of the carrier A and the flow 1 and flow 2 of the carrier B for each valid time range of the CID. It is composed of a CID, and stores the CID in each flow every 15 minutes. Flow 1, flow 2, etc. represent IP data flows, in which various data (protocol type, source IP address, destination IP address, source port number, and destination port number) are stored.

  Here, the CID table management unit 19 monitors the time when 15 minutes such as 0:15 and 0:30 have elapsed since the time started from 0:00. For example, when it is determined that the time has reached 0:15, various data of the CID and the IP data flow are read from the flow / time-specific CID allocation table 40 when the valid time range of the CID is 0:15 to 0:30 For each read CID, a CID record including various data of the CID, IP header, and UDP header is generated, and after the CID table 10 is cleared, the generated CID record is stored in the CID table 10. Thereby, based on the CID allocation table 40 classified by flow and time, CID to be used can be changed for every time.

  The compressed header packet generation unit 17 inputs an IP packet, distinguishes a plurality of input IP packets based on information (IP header and UDP header) described in the header of the IP packet, and specifies an IP data flow To do. Then, the compressed header packet generation unit 17 reads out CIDs corresponding to various data in the IP data flow (protocol type, transmission source IP address, destination IP address, transmission source port number, and destination port number) from the CID table 10, Determine the CID. The compressed header packet generator 17 generates a compressed header packet and outputs it to the transmission controller 18.

  The transmission control unit 18 receives the compressed header packet generated by the compressed header packet generation unit 17 and transmits the compressed header packet to the one-way transmission path 3 as shown in FIG.

(Receiving terminal)
Next, the configuration and processing of the receiving terminal will be described. FIG. 16 is a block diagram illustrating a configuration of a receiving terminal according to the third embodiment. The reception terminal 2-3 includes a reception control unit 28, a compressed header packet processing unit 29, a CID table management unit 30, a CID table 20, and a flow / time-specific CID allocation table 50. The CID table 20 is stored in the storage means and has the same configuration as the CID table shown in FIG. The flow / time-specific CID allocation table 50 is stored in a storage medium such as a non-volatile memory as a storage unit, and is the same table as the flow / time-specific CID allocation table 40 described above. That is, the receiving terminal 2-3 includes a flow / time CID allocation table 50 having the same contents as the flow / time CID allocation table 40 of the transmission terminal 1-3 shown in FIG.

  When the CID table management unit 30 inputs time information from a timer (not shown) and determines that the predetermined time has been reached, the CID and IP data flow data corresponding to the predetermined time are determined from the flow / time-specific CID allocation table 50. After reading (protocol type, source IP address, destination IP address, source port number and destination port number), generating a CID record consisting of various data of CID, IP header, and UDP header, and clearing the CID table 20 The generated CID record is stored in the CID table 20. The CID table management unit 30 and the CID allocation table 50 by flow / time are the same as the CID table management unit 19 and the CID allocation table 40 by flow / time shown in FIG. Detailed description is omitted.

  The reception control unit 28 receives a packet from the one-way transmission path 3, and distinguishes the packet based on CID_header_type (CID header type). The compressed header packet processing unit 29 inputs the compressed header packet distinguished by the reception control unit 28, extracts the CID that is the compressed header from the compressed header packet, searches the CID table 20 using the CID as a key, and has the same CID Read the IP header and UDP header of the CID record. Then, the compressed header packet processing unit 29 generates and outputs an IP packet.

  As described above, according to the third embodiment, the transmission terminal 1-3 stores a fixed CID and header information using the flow / time-specific CID allocation table 40 in which fixed data set in advance is stored. The CID table 10 is generated, and the compressed header packet is generated and transmitted using the CID table 10. Further, the receiving terminal 2-3 generates the CID table 20 using the same flow / time CID allocation table 50 as the flow / time CID allocation table 40, and uses the CID table 20 as the header information. Restore. Here, the CID table 10 and the CID table 20 are tables having the same contents. As described above, the transmission terminal 1-3 and the reception terminal 2-3 use the same fixed CID tables 10 and 20, so that the correspondence between the CID and the header information is as follows. It is possible to avoid inconsistency between the two.

  The flow / time-specific CID allocation tables 40 and 50 shown in FIG. 17 are configured such that different CIDs are allocated even for the same IP data flow according to the time in 15-minute increments. Even if changes, it may be a value that does not change and the same value is assigned throughout the day.

It is a figure which shows schematic structure of the transmission system containing the transmission terminal and receiving terminal by embodiment of this invention. FIG. 3 is a block diagram illustrating a configuration of a transmission terminal according to the first embodiment. FIG. 3 is a block diagram illustrating a configuration of a receiving terminal according to the first embodiment. (1) is a figure which shows the structure of the CID record update packet of IPv4. (2) is a diagram showing a configuration of an IPv6 CID record update packet. It is a figure which shows the structure of a CID record deletion packet. It is a figure which shows the structure of the CID record deletion packet which deletes a some CID record. It is a figure which shows the structure of a CID record all deletion packet. It is a figure explaining the transmission order of a CID record update packet, a CID record deletion packet, and a compression header packet. It is a figure explaining the transmission order of a CID record deletion packet, a full header packet, and a compression header packet. It is a figure explaining the transmission order of a CID record all deletion packet, a CID record update packet, and a compression header packet. It is a block diagram which shows the structure of the transmission terminal of Example 2. FIG. 6 is a block diagram illustrating a configuration of a receiving terminal according to Embodiment 2. FIG. It is a figure which shows the structure of the address map table (AMT) used in Example 2. FIG. It is a figure explaining the transmission order in the case of updating a CID table by an address map table (AMT). FIG. 10 is a block diagram illustrating a configuration of a transmission terminal according to a third embodiment. 6 is a block diagram illustrating a configuration of a receiving terminal according to Embodiment 3. FIG. It is a figure which shows the structure of the CID allocation table classified by flow and time. It is a figure explaining the header compression system by a full header packet, a compression header packet, and a CID table. (1) is a diagram showing a configuration of an IPv4 CID table. (2) is a diagram showing the configuration of an IPv6 CID table. (1) is a diagram showing a configuration of an IPv4 full header packet. (2) is a diagram showing a configuration of an IPv4 compressed header packet. (3) is a diagram illustrating a configuration of an IPv6 full header packet. (4) is a diagram showing a configuration of an IPv6 compressed header packet. It is a figure which shows the structure of IPv4_header_wo_length in the full header packet of IPv4. It is a figure which shows the structure of IPv6_header_wo_length in the full header packet of IPv6. It is a figure which shows the structure of UDP_header_wo_length in the full header packet of IPv4 and IPv6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sending terminal 2 Receiving terminal 3 One-way transmission line 10, 20 CID table 11 Full header packet / compressed header packet generating unit 12 Control packet generating unit 13, 16, 18 Transmission control unit 14, 17 Compressed header packet generating unit 15 AMT generation Units 19, 30 CID table management units 21, 25, 28 reception control unit 22, control packet processing unit 23 full header packet processing units 24, 27, 29 compressed header packet processing unit 26 AMT processing unit 40, 50 CID allocation by flow / time table

Claims (9)

When a set of a plurality of IP packets is transmitted for each IP data flow, header compression of the IP packet constituting the IP data flow is replaced with a context identifier (CID) for specifying the IP data flow. In a transmitting terminal that transmits a compressed header packet including the CID,
A CID table composed of CID records including CID and header information;
CID is determined based on header information of IP packets constituting the IP data flow, a CID record including the CID and header information is generated and written to the CID table, a compressed header packet including the CID is generated, A compressed header packet generator for deleting the CID record from the CID table after generation of all the compressed header packets constituting the IP data flow is completed;
Based on the CID table, a CID record update packet for writing a CID record including a CID and header information to a CID table provided on the packet receiving side, and a CID record indicated by the CID are sent to the receiving side. A control packet generation unit for generating a CID record deletion packet for deletion from the provided CID table;
After transmitting the CID record update packet generated by the control packet generator, the compressed header packet generated by the compressed header packet generator is transmitted, and then the CID record generated by the control packet generator is deleted. A transmission terminal comprising: a transmission control unit that transmits a packet. When a set of a plurality of IP packets is transmitted for each IP data flow, header compression of the IP packet constituting the IP data flow is replaced with a context identifier (CID) for specifying the IP data flow. In a transmitting terminal that transmits a compressed header packet including the CID,
A CID table composed of CID records including CID and header information;
Full header packet including CID and header information by determining CID based on header information of IP packet constituting IP data flow, generating CID record including CID and header information, and adding to CID table And generating a compressed header packet by reading out the CID from the CID table, and deleting the CID record from the CID table after generation of all the compressed header packets constituting the IP data flow is completed. A full header packet / compressed header packet generator,
Based on the CID table, a control packet generator for generating a CID record deletion packet for deleting the CID record indicated by the CID from the CID table provided on the receiving side;
A transmission control unit that transmits a compressed header packet after transmitting the full header packet generated by the full header packet / compressed header packet generation unit, and then transmits a CID record deletion packet generated by the control packet generation unit; A transmission terminal comprising: In the transmission terminal according to claim 1,
The control packet generation unit generates a CID record deletion packet for deleting all CID records from the CID table provided on the receiving side instead of the CID record deletion packet for deleting the CID record indicated by the CID,
The transmission control unit transmits a CID record update packet after transmitting the CID record deletion packet generated by the control packet generation unit, and then transmits the compressed header packet generated by the compressed header packet generation unit. A transmitting terminal characterized by that. In the transmission terminal according to claim 1 or 2,
The transmission terminal, wherein the CID record deletion packet is a packet for deleting a CID record that is not stored in the CID table of the transmission terminal. When a set of a plurality of IP packets is transmitted for each IP data flow, header compression of the IP packet constituting the IP data flow is replaced with a context identifier (CID) for specifying the IP data flow. In a transmitting terminal that transmits a compressed header packet including the CID,
A CID table composed of CID records including CID and header information;
CID is determined based on header information of IP packets constituting the IP data flow, a CID record including the CID and header information is generated and written to the CID table, a compressed header packet including the CID is generated, A compressed header packet generator for deleting the CID record from the CID table after generation of all the compressed header packets constituting the IP data flow is completed;
Based on the CID table, the correspondence between the source address and destination address of the packet and the CID is described, and a transmission control signal used to update the CID record of the CID table provided on the side receiving the packet A transmission control signal generator for generating
A transmission terminal that transmits a transmission control signal generated by the transmission control signal generation unit, and then transmits a compressed header packet generated by the compressed header packet generation unit. In the receiving terminal that receives the header header compressed by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow and performing header compression,
A CID table composed of CID records including CID and header information;
CID record update packet for adding the compressed header packet, CID and header information to the CID table, and a CID record deletion packet for deleting the CID record indicated by the CID or all CID records from the CID table A reception control unit for distinguishing received packets;
For the CID record update packet distinguished by the reception control unit, a CID record including the CID and header information of the CID record update packet is added to the CID table, and the CID record deletion packet distinguished by the reception control unit A CID record indicated by the CID of the CID record deletion packet or a control packet processing unit that deletes all CID records from the CID table;
  A compressed header packet processing unit that reads out header information from the CID table using the CID of the compressed header packet for the compressed header packet distinguished by the reception control unit, and generates an IP packet constituting the IP data flow; A receiving terminal comprising: In the receiving terminal that receives the header header compressed by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow and performing header compression,
A CID table composed of CID records including CID and header information;
A reception control unit that receives the compressed header packet, a full header packet including CID and header information, and a CID record deletion packet for deleting the CID record indicated by the CID from the CID table;
For the full header packet distinguished by the reception control unit, a CID record including the CID of the full header packet and header information is written to the CID table, and an IP packet constituting an IP data flow is generated from the full header packet. A compressed header packet processing unit that reads out header information from the CID table using the CID of the compressed header packet for the compressed header packet distinguished by the reception control unit, and generates an IP packet constituting the IP data flow When,
A receiving terminal comprising: a control packet processing unit that deletes, from the CID table, a CID record indicated by a CID of the CID record deletion packet for the CID record deletion packet distinguished by the reception control unit. In the receiving terminal that receives the header header compressed by replacing the header information of the IP packet constituting the IP data flow with a context identifier (CID) for specifying the IP data flow and performing header compression,
A CID table composed of CID records including CID and header information;
A reception control unit that receives a transmission control signal in which a correspondence relationship between a source address and a destination address of an IP packet constituting the IP data flow and a CID is described, and the compressed header packet, and distinguishes these signals and packets When,
A transmission control signal processing unit that updates the CID table with a CID record including a CID and header information of the transmission control signal for the transmission control signal distinguished by the reception control unit;
A compressed header packet processing unit that reads out header information from the CID table using the CID of the compressed header packet for the compressed header packet distinguished by the reception control unit, and generates an IP packet constituting the IP data flow; A receiving terminal comprising: A transmission system comprising: the transmission terminal according to any one of claims 1 to 5; and the reception terminal according to any one of claims 6 to 8.

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