JP2009302743A - Session information transmitting apparatus and computer program - Google Patents

Abstract

An object of the present invention is to suppress duplication of session information to a terminal device and reduce network traffic.
A location management database that stores a home address and a care-of address assigned to a terminal device connected to a home network or an external network in association with each other, and for each combination of session information and the home address of the terminal device. A transmission history database for storing transmission history information indicating whether or not the session information has been transmitted to the care-of address of the terminal device, and receives session information distributed from the advertisement server, and receives the received session information. Session information received by reading the home address of the terminal device that has not been transmitted from the transmission history database, reading the care-of address associated with the read home address from the location management database, and receiving the read care-of address Send.
[Selection] Figure 2

Description

  The present invention relates to a session information transmitting apparatus and a computer program, and more particularly to a session information transmitting apparatus and a computer program for transmitting a multicast packet of multicast session information (hereinafter referred to as session information) to a terminal apparatus.

Conventionally, a content distribution server that operates according to a session announcement protocol (SAP: Session Non-Patent Document 2), regardless of whether or not the session information to be distributed has already been distributed to the terminal device of the distribution destination, Distribution was performed at a predetermined distribution interval. Therefore, the terminal device may receive the already acquired session information in duplicate. For this reason, there is a problem in that the network traffic increases due to the session information distribution process.
In addition, when a home agent having mobile IP (Mobile Internet Protocol: see Non-Patent Document 5) transfers session information to a plurality of terminal devices connected to an external network, the session information originally distributed by multicast is: Home agent converts to unicast and forwards. Therefore, the duplicate distribution of session information as described above increases according to the number of terminal devices. Therefore, there has been a problem that the amount of network communication increases.

Here, Patent Document 1 discloses a technique for reducing the amount of transferred packets. In the technique disclosed in Patent Document 1, the home agent includes a data table for determining whether or not the packet addressed to the home address of the terminal device can be transferred for each subnetwork of the external network. When the home agent is permitted to transfer to the subnetwork of the external network to which the terminal device is connected, the home agent transfers the packet addressed to the terminal device. As a result, an increase in network traffic can be suppressed.
JP 2005-175589 A RFC2236 "Internet Group Management Protocol, Version2 (IGMPv2)" RFC2974 "Session Announcement Protocol (SAP)" RFC4566 "Session Description Protocol (SDP)" RFC2362 "Protocol Independent Multicast-Sparse Mode (PIM-SM)" RFC3344 "Mobile IP" Detailed explanation Mobile IP Fumio Teraoka

(1) However, in the technology disclosed in Patent Document 1, the home agent determines whether or not to transfer a packet based only on the subnet of the external network to which the terminal device is connected. For this reason, the technique disclosed in Patent Document 1 has a problem that it is not possible to prevent duplicate distribution of session information.
(2) Further, even if the terminal device transmits a multicast reception request or a session information reception request by an IGMP message (see Non-Patent Document 1) or the like to the content distribution server, the content distribution server transmits the session information until the next distribution timing. Do not deliver. In other words, a delay corresponding to the session information distribution interval occurs at the maximum before the terminal device receives the desired session information. Therefore, even if the terminal device transmits a session information reception request, the terminal device cannot receive desired session information immediately.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent duplicate session information from being transmitted to a terminal device and to reduce the network traffic.
Another object of the present invention is to shorten the time required for the terminal device to receive the session information after transmitting the session information reception request.

[1] In order to solve the above problem, the session information transmitting apparatus according to an aspect of the present invention stores a home address and a care-of address assigned to a terminal device connected to a home network or an external network in association with each other. For each combination of a management database, a session information receiving unit (for example, receiving unit 101 in the embodiment) that receives session information distributed from the content distribution server, and the session information and the home address of the terminal device, the session information A transmission history database (for example, a transfer history database in the embodiment) that stores transmission history information (for example, a flag stored in the transfer history database 106 in the embodiment) indicating whether or not is transmitted to the care-of address of the terminal device 106) and received The home address of the terminal device to which no station information is transmitted is read from the transmission history database, the care-of address associated with the read home address is read from the location management database, and the read care-of address is addressed to the address A session information transmission unit (for example, the distribution management unit 111 and the transmission unit 112 in the embodiment) that transmits the received session information.
According to this configuration, for each combination of the session information and the home address of the terminal device, the session information is stored in the transmission history database as to whether or not the session information has been transmitted to the care-of address of the terminal device. Do not send session information that has already been sent. Therefore, it is possible to prevent duplicate session information from being transmitted to the terminal device and to reduce the network traffic.

[2] Further, according to one aspect of the present invention, in the above-described session information transmission apparatus, among the session information storage unit that stores the received session information and the session information stored in the session information storage unit, It is determined whether there is session information that matches the received session information, and if there is no matching session information, the received session information is written in the session information storage unit and the session in the transmission history database A writing determination unit that rewrites the transmission history information related to the information to transmission history information indicating that the information is not transmitted, and does not write the received session information in the session information storage unit when there is matching session information; , Further comprising.
According to this configuration, the session information newly written in the session information storage unit can be transmitted to each terminal device.

  [3] A computer program according to an aspect of the present invention includes a location management database that stores a home address and a care-of address assigned to a terminal device connected to a home network or an external network in association with each other, and the session information A content distribution server for a computer comprising: a transmission history database for storing transmission history information indicating whether or not the session information is transmitted to the care-of address of the terminal device for each combination with the home address of the terminal device Session information receiving process for receiving session information distributed from the terminal, and the home address of the terminal device to which the received session information has not been transmitted is read from the transmission history database, and the awareness associated with the read home address Address Read from the management database, and session information transmission process of transmitting the received session information to the care-of address that has been read, and executes processing of.

[4] In addition, a session information transmission device according to an aspect of the present invention includes a session information reception unit (for example, the reception unit 101 in the embodiment) that receives session information transmitted from the content distribution server at intervals, and a reception A session information storage unit that stores the received session information, and a session information request reception unit that receives the session information request that requests the session information (for example, a reception request in the embodiment) from the terminal device (for example, in the embodiment) In response to the received session information request, the reception unit 101) reads the session information from the session information storage unit, and transmits the read session information to the terminal device (for example, Distribution management unit 111 and transmission unit 112) in the embodiment, Characterized by comprising.
According to this configuration, session information distributed from the content distribution server at intervals is stored in the session information storage unit. When a session information request is transmitted from the terminal device, the session information stored in the session information storage unit is transmitted to the terminal device regardless of whether or not the content distribution server is to distribute the session information. . Therefore, it is possible to shorten the time required for the terminal device to receive the session information after transmitting the session information request.

[5] Further, according to one aspect of the present invention, in the above session information transmission device, it is determined whether or not the received session information and the session information stored in the session information storage unit overlap. A write determination unit that writes the received session information to the session information storage unit if not, and does not write the received session information to the session information storage unit if there is a duplicate. It is characterized by.
According to this configuration, session information is stored in the session information storage unit so as not to overlap. Therefore, it is possible to effectively use the storage capacity of the session information storage unit.

  [6] A computer program according to an aspect of the present invention provides session information reception for receiving a session information in a computer including a session information storage unit that stores session information transmitted from the content distribution server at intervals. A process for writing the received session information into the session information storage unit, a session information request for receiving a session information request for requesting the session information from a terminal device, and the received session information request. In response to this, the session information is read from the session information storage unit, and the session information transmission process of transmitting the read session information to the terminal device is executed.

According to the present invention, it is possible to prevent the session information from being duplicated and delivered to the terminal device and reduce the network traffic.
In addition, according to the present invention, it is possible to reduce the time required for the terminal device to receive the session information after transmitting the session information reception request. Furthermore, it is possible to obtain session information at the timing when the terminal device transmits a session information reception request.

  FIG. 1 is a system configuration diagram showing a functional configuration of a network system 1 including a communication apparatus according to an embodiment of the present invention. The network system 1 includes a plurality of content distribution servers 25-1 to 25 -N, a home agent 211, a terminal device 201 connected to the home network 221 or the external network 231, a router 233 provided in the external network 231, and an external network. The DHCP server (Dynamic Host Configuration Protocol Server) 234 is configured.

  Each content distribution server 25-1 to 25-N transmits a multicast stream and its session information 26-1 to 26-N to a plurality of terminals by transmitting packets addressed to a common multicast group address in accordance with SAP. Distribute to each of the devices 201. Each session information 26-1 to 26 -N is SDP (Session Description Protocol) data, and includes a program name, a transmission source, and a distribution destination address (multicast group address) of streaming data.

The router 233 is provided at the boundary between the IP network and the external network 231, and performs a relay process for IP packets transmitted from the IP network to the external network 231 and IP packets transmitted from the external network 231 to the IP network.
The DHCP server 234 assigns a care-of address to the terminal device 201 connected to the external network 231.
The terminal device 201 communicates with the home agent 211 according to the mobile IP. The terminal device 201 is assigned a home address HoA 222 in the home network 221 and assigned a care-of address CoA 232 by the DHCP server 234 in the external network 231.

  The home agent 211 manages the location of the terminal device 201 according to the mobile IP, and transfers an IP packet addressed to the terminal device 201 to the terminal device 201. When the terminal device 201 is connected to the external network 231, the home agent 211 adds an IP header whose destination is the care-of address CoA 232 to the IP packet addressed to the home address HoA 222 and transmits the IP packet to the external network 231.

Next, details of the home agent 211 will be described.
FIG. 2 is a block diagram showing a functional configuration of the home agent 211. As shown in the figure, the home agent 211 includes a reception unit 101, a packet determination unit 102, a session information extraction unit 103, a session information storage unit 104, a write determination unit 105, a transfer history database 106, a reception request. The storage unit 107, the reception request writing unit 108, the location management database 109, the location management unit 110, the distribution management unit 111, and the transmission unit 112 are configured.

The receiving unit 101 receives an IP packet from the IP network or the home network 221.
The packet determination unit 102 refers to the header of the IP packet received by the reception unit 101 and includes whether the IP packet is an IP packet including session information, an IP packet including a reception request, or a location registration request. It is determined whether it is an IP packet or an IP packet other than these.

The session information extraction unit 103 extracts the session information, the IP address of the transmission source of the IP packet, and the IP address of the transmission destination (IP header information) from the IP packet determined to include the session information by the packet determination unit 102. .
The session information storage unit 104 stores session information in association with IP header information.

  The writing determination unit 105 compares the session information extracted by the session information extraction unit 103 with the session information stored in the session information storage unit 104, and uses the extracted session information as a session according to the comparison result. Write to the information storage unit 104. Specifically, the write determination unit 105 writes the extracted session information to the session information storage unit 104 when either of the following conditions (1) or (2) is satisfied, and both conditions are satisfied. If not, the extracted session information is discarded.

(1) When the session identification information included in the session information extracted by the session information extraction unit 103 and the session identification information of all the session information stored in the session information storage unit 104 do not match (2) When the condition (1) is not satisfied and the session information extracted by the session information extraction unit 103 and the session information stored in the session information storage unit 104 are respectively compared between corresponding fields, If at least some of those values are different

  The transfer history database 106 stores transfer history data indicating whether each session information has been transferred to each terminal device.

The reception request storage unit 107 stores request history data.
The reception request writing unit 108 extracts the home address HoA 222 and the multicast group address GA271 from the IP packet determined to include the reception request by the packet determination unit 102, and corresponds the extracted home address HoA222 to the multicast group address GA271. At the same time, it is written in the reception request storage unit 107.

The location management database 109 stores location management data in which a home address and a care-of address are associated with each other.
The location management unit 110 extracts the home address HoA 222 and the care-of address CoA 232 from the IP packet determined to include the location registration request by the packet determination unit 102, and associates the home address HoA 222 with the care-of address CoA 232 to the location management database 109. Write to.

The distribution management unit 111 transfers the IP packet whose destination is the multicast address or the home address of the terminal device 201 among the IP packets received by the receiving unit 101 to the care-of address of the terminal device 201. When transferring an IP packet including session information among IP packets whose destination is a multicast address, the distribution management unit 111 refers to the transfer history database 106, the reception request storage unit 107, and the location management database 109. Then, a new header is added (encapsulated) to the IP packet with the care-of address of the terminal device 201 to which the session information is not transmitted as the transfer destination address, and the IP packet including the session information is transferred.
The transmission unit 112 transmits the IP packet to the IP network or the home network 221 in accordance with the transmission request from the distribution management unit 111.

  FIG. 3 is a schematic diagram showing a data structure of session information. The session information includes version information (v), session identification information (o), session name (s), connection data (c), session active time zone (t), media information (m), and attribute information (a ) Field. A specific value is given to each field by the content distribution servers 25-1 to 25-N.

  FIG. 4 is a schematic diagram illustrating a configuration of data stored by the session information storage unit 104. This data includes, for each session (that is, for each session identification information) distributed to the terminal device 201 by the content distribution servers 25-1 to 25-N, the session information and the IP header information of the IP packet including the session information. Are stored in association with each other. For example, in FIG. 4, this data includes session identification information “News XXX XXX IN IP4 aaa.or.jp”, and values “0” (v field) and “251@test.com” of other fields of the session information. (S field), “IN IP4 239.1.1.1” (c field), “28733797496 287394696” (t field), “Video 2356 RTP / AVP 31” (m field), and IP header information “192. 168.0.251 ”(source address) and“ 224.2.127.254 ”(destination address) are stored in association with each other.

  FIG. 5 is a schematic diagram showing a configuration of transfer history data stored by the transfer history database 106. The transfer history data is held for each session identification information by associating the session identification information with a flag indicating whether or not the latest session information has been transferred for each terminal device 201 that has requested distribution of the session information. It is data. When the flag is “0”, it indicates that the transfer has not been performed, and when the flag is “1”, the transfer has been completed. For example, in FIG. 5, the value of the flag corresponding to the session identification information “News XXX XXX IN IP4 aaa.or.jp” and the home address “192.168.1.1” is “1”. Represents that the latest session information of the session identification information has been transferred to the terminal device. Similarly, in FIG. 5, the value of the flag corresponding to the session identification information “SPORTS XXX XXX IN IP4 aaa.or.jp” and the home address “192.168.1.1” is “0”. The history data indicates that the latest session information of the session identification information has not been transferred to the terminal device.

  FIG. 6 is a schematic diagram illustrating a configuration of request history data stored by the reception request storage unit 107. The request history data is data stored for each home address in association with the home address and one or a plurality of multicast group addresses. For example, in FIG. 6, this data is distributed to the terminal device to which the home address “192.168.1.1” is assigned, the session information distributed to the multicast group address GA271 and the multicast group address GA272. Indicates that it is requesting reception of session information.

  FIG. 7 is a schematic diagram showing the configuration of location management data stored by the location management database 109. The location management data is data stored for each home address in association with a home address and a care-of address. For example, in FIG. 7, the first line data in the figure indicates that the care-of address of the terminal device to which the home address “192.168.1.1” is assigned is “201.167.101.211”. Represents. In addition, since the care-of address is not stored in the location management database 109 for the data in the second row in the figure, the terminal device to which the home address “192.168.1.2” is assigned is connected to the home network 221. It represents that.

Next, the operation and processing procedure of the home agent 211 will be described.
8 and 9 are flowcharts showing a processing procedure when the home agent 211 receives a multicast packet.

As shown in FIG. 8, in step S01, the receiving unit 101 first receives a multicast packet.
Next, in step S02, the packet determination unit 102 determines whether the received packet includes session information. Specifically, the packet determination unit 102 reads the destination address of the received IP packet and determines whether the destination address is a multicast group address. If the destination address is a multicast group address, the packet determination unit 102 determines whether the data of the received IP packet matches the SAP syntax (syntax rule). When the data of the received IP packet matches the SAP syntax, the packet determination unit 102 determines that the IP packet includes session information.

As a result of the determination, if the received packet does not include session information (step S02: NO), the process proceeds to the next step S03.
As a result of the determination, if the received packet includes session information (step S02: YES), the process proceeds to the next step S04.

  In step S03, the distribution management unit 111 transfers the received multicast packet to the terminal device 201 via the transmission unit 112, and the process of the entire flowchart ends. Specifically, the distribution management unit 111 extracts a multicast group address from the received multicast packet. Next, the distribution management unit 111 refers to the reception request table stored in the reception request storage unit 107, and reads the home address associated with this multicast group address. Next, the distribution management unit 111 refers to the position management table stored in the position management database 109 and reads the care-of address associated with each read home address. Then, the distribution management unit 111 transfers the received multicast packet to each read care-of address, and ends the processing of the entire flowchart. At this time, if there is no care-of address associated with the home address, the distribution management unit 111 distributes the received multicast packet as it is to the home network 221 and ends the processing of the entire flowchart.

In step S04, the session information extraction unit 103 extracts session information and IP header information from the received multicast packet.
Next, in step S05, the write determination unit 105 extracts session identification information from the extracted session information.

  Next, in step S06, the write determination unit 105 searches the session information table using the extracted session identification information as a key, and the same session identification information as the extracted session identification information is already stored in the session information storage unit 104. It is determined whether it has been done.

When the same session identification information as the extracted session identification information is not stored in the session information storage unit 104 (step S06: NO), the process proceeds to the next step S07.
When the same session identification information as the extracted session identification information is stored in the session information storage unit 104 (step S06: YES), the process proceeds to the next step S10.

  In step S07, the write determination unit 105 determines that the extracted session information is session information, and stores the extracted session information and IP header information in association with the session identification information of the session information. Write to part 104.

  Next, in step S08, the distribution management unit 111 newly registers the session identification information of the extracted session information in the transfer history database 106.

  Next, in step S09, the distribution management unit 111 transfers the extracted session information to the terminal device 201, updates the transfer history data stored in the transfer history database 106, and ends the processing of the entire flowchart. . Specifically, the distribution management unit 111 searches the reception request table stored in the reception request storage unit 107 using the session identification information as a key, and the home address of the terminal device 201 that is requesting reception of the session information. Is read. Next, the distribution management unit 111 refers to the position management table stored in the position management database 109 and reads the care-of address associated with each read home address. Then, the distribution management unit 111 transfers the multicast packet including the new session information to each read care-of address. At this time, if there is no care-of address associated with the home address, the distribution management unit 111 distributes the multicast packet including the new session information to the home network 221 as it is.

Moving to FIG. 9, in step S <b> 10, the write determination unit 105 determines the correspondence between the value of each field of the extracted session information and the value of each field of the session information stored in the session information storage unit 104. It is determined whether or not the field values to be matched match.
As a result of the determination, when the value of each field of the extracted session information and the value of each field of the session information stored in the session information storage unit 104 match (step S10: YES) ) Proceeds to the next step S11.

As a result of the determination, when the value of each field of the extracted session information and the value of each field of the session information stored in the session information storage unit 104 do not match (step S10: NO) ) Proceeds to step S12.
In step S11, the write determination unit 105 discards the extracted session information and ends the process of the entire flowchart.

  Next, in step S12, the write determination unit 105 searches the session information and IP header information stored in the session information storage unit 104 using the session identification information of the extracted session information as a key. The information and the IP header information are rewritten to the extracted session information and the IP header.

  Next, in step S13, the distribution management unit 111 refers to the transfer history data stored in the transfer history database 106, and sets all the flags associated with the session identification information of the extracted session information to “0”. Rewrite as

  Next, in step S14, the distribution management unit 111 transfers the extracted session information to the terminal device 201, updates the transfer history data stored in the transfer history database 106, and ends the processing of the entire flowchart. . Specifically, the distribution management unit 111 searches the request history data stored in the reception request storage unit 107 using the session identification information as a key, and the home address of the terminal device 201 requesting reception of the session information Is read. Next, the distribution management unit 111 refers to the position management stored in the position management database 109 and reads the care-of address associated with each read home address. Then, the distribution management unit 111 transfers the multicast packet including the update session information to each read care-of address. At this time, if there is no care-of address associated with the home address, the distribution management unit 111 distributes the multicast packet including the update session information to the home network 221 as it is.

FIG. 10 is a flowchart showing a processing procedure when the home agent 211 receives a unicast packet.
As shown in the drawing, in step S21, the receiving unit 101 first receives a unicast packet.

Next, in step S22, the packet determination unit 102 determines whether or not the received packet includes a reception request.
As a result of the determination, if the received packet does not include a reception request (step S22: NO), the process proceeds to the next step S23.
As a result of the determination, if the received packet includes a reception request (step S22: YES), the process proceeds to the next step S24.

  In step S23, the position management unit 110 or the distribution management unit 111 performs the same process as that of the prior art. Specifically, when the received packet includes a location registration request, the location management unit 110 registers the home address and care-of address in the location management database 109, and the received packet does not include a location registration request. In this case, the distribution management unit 111 transfers the received packet to the home address or care-of address.

In step S24, the reception request writing unit 108 extracts the home address and multicast group address from the received packet.
Next, in step S <b> 25, the distribution management unit 111 reads the session information stored in the session information storage unit 104 in association with the extracted multicast group address from the session information storage unit 104.

Next, in step S <b> 26, the distribution management unit 111 reads the care-of address stored in the position management database 109 in association with the extracted home address from the position management database 109.
Next, in step S27, the distribution management unit 111 transfers the read session information to the read care-of address, and the process of the entire flowchart ends.

<Modification>
FIG. 11 is a schematic diagram illustrating a configuration of a first modification of transfer history data stored in the transfer history database 106. The transfer history data according to the present embodiment holds a flag indicating whether or not the transfer has been performed, but the transfer history data illustrated in FIG. 11 holds transfer count information indicating the number of transfers. For example, in FIG. 11, the first line of the data in the figure shows the session information whose session identification information is “News XXX XXX IN IP4 aaa.or.jp”, and the distribution management unit 111 uses the home address “192.168 .. The home address “192.168.1.100” is assigned twice to the terminal device to which 1.1 ”is assigned and the terminal address to which the home address“ 192.168.1.2 ”is assigned 0 times. Indicates that it has been transferred twice to the terminal device.
When the transfer history database 106 stores the transfer history data shown in FIG. 11, the distribution management unit 111 counts the number of times the session information is transferred based on the transfer number information, and the upper limit value of the transfer number for which the transfer number information is provided in advance. Transfer session information until is reached.

FIG. 12 is a schematic diagram illustrating a configuration of a second modification of transfer history data stored by the transfer history database 106. The transfer history data shown in FIG. 12 holds the time from when the home address of each terminal device 201 is registered in the transfer history data until the transfer is stopped (hereinafter referred to as “transferable time”). For example, in FIG. 12, the home address “192.168.1.1” of the session information whose session identification information is “News XXX XXX IN IP4 aaa.or.jp” is assigned to the first line of the data in the figure. The transferable time for the assigned terminal device is 200 seconds, the transferable time for the terminal device to which the home address “192.168.1.2” is assigned is 50 seconds, and the home address “192.168.1.100” is assigned. This indicates that the transferable time for the terminal device being set is 400 seconds.
When the transfer history database 106 stores the transfer history data shown in this figure, the distribution management unit 111 measures the time from the time when the home address of each terminal device 201 is registered in the transfer history data, and the transferable time. Session information is transferred until elapses.

  In this embodiment, the reception request is information indicating that the terminal device that is the transmission source of the reception request requests reception of the session information. However, the terminal device that is the transmission source of the reception request receives the multicast stream. It may be information indicating that it is requested. Also in this case, as described above, the reception request includes the home address and multicast group address of the terminal device 201 that is the transmission source of the reception request.

  Incidentally, in the mobile IP, there are a case where a terminal device performs transmission of a Binding Update message and reception and decapsulation of a packet transferred by a home agent, and a case where a router of an external network performs. As terms relating to mobile IP, the former is called “Co-located Care-of Address mode” and the latter is called “FA mode”. For example, when the router connected between the external network 231 and the IP network has the FA function, the mobile IP can be controlled by the “FA mode”, and the router 233 can transmit a Binding Update message, It is possible to perform reception of the packet transferred by 211 and decapsulation for deleting the IP header information of the encapsulated packet.

  As described above, the mobile IP has the “Co-located Care-of Address mode” and the “FA mode”. In the present embodiment, the mobile IP of the communication device according to the present invention is “Co-located care mode”. The case has been described as “care-of address mode”. However, the communication device according to the present invention is realized by adding a session information management function to the home agent, and for the terminal device and the router of the external network, the function unique to the present invention is achieved. Does not require addition. For this reason, the communication apparatus according to the present invention can also be applied in the “FA mode”, and the same effect as when applied in the “Co-located Care-of Address mode” of the present embodiment can be expected.

Note that the function of the session information transmitting apparatus in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. The “computer system” here includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as a hard disk built in the computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.
As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design etc. of the range which does not deviate from the summary of this invention are included.

1 is a system configuration diagram illustrating a functional configuration of a network system including a communication device according to an embodiment of the present invention. It is a block diagram which shows the function structure of a home agent. It is the schematic which shows the structure of the data of session information. It is the schematic which shows the structure of the data memorize | stored by a session information storage part. It is the schematic which shows the structure of the transfer history data memorize | stored by the transfer history database. It is the schematic which shows the structure of the request history data memorize | stored by the reception request memory | storage part. It is the schematic which shows the structure of the position management data memorize | stored by a position management database. It is a flowchart which shows the process sequence when a home agent receives a multicast packet. It is a flowchart which shows the process sequence when a home agent receives a multicast packet. It is a flowchart which shows the process sequence when a home agent receives a unicast packet. It is the schematic which shows an example of the transfer history data memorize | stored in the transfer history database in the case of transferring session information until it reaches an upper limit by a counter. It is the schematic which shows an example of the transfer history data memorize | stored in a transfer history database.

Explanation of symbols

101 reception unit 102 packet determination unit 103 session information extraction unit 104 session information storage unit 105 write determination unit 106 transfer history database 107 reception request storage unit 108 reception request writing unit 109 position management database 110 position management unit 111 distribution management unit 112 Transmission unit 201 Terminal device 211 Home agent 221 Home network 231 External network 233 Router 234 DHCP server 25-1 to 25-N Content distribution server

Claims (6)

A location management database for storing a home address and a care-of address assigned to a terminal device connected to a home network or an external network in association with each other;
A session information receiving unit for receiving session information distributed from the content distribution server;
For each combination of the session information and the home address of the terminal device, a transmission history database storing transmission history information indicating whether the session information has been transmitted to the care-of address of the terminal device;
The home address of the terminal device to which the received session information is not transmitted is read from the transmission history database, the care-of address associated with the read home address is read from the location management database, and the read care-of address is read. A session information transmission unit for transmitting the received session information to
A session information transmitting apparatus comprising: In the session information transmitting device according to claim 1,
A session information storage unit for storing the received session information;
Of the session information stored in the session information storage unit, it is determined whether there is session information that matches the received session information, and if there is no matching session information, the received session information is The session information received when there is matching session information that is written in the session information storage unit and rewritten with transmission history information indicating that the session information in the transmission history database is not transmitted. Is not written in the session information storage unit,
A session information transmitting apparatus, further comprising: For each combination of a location management database that associates and stores a home address and a care-of address assigned to a terminal device connected to a home network or an external network, and the session information and the home address of the terminal device, the session information is In a computer comprising a transmission history database for storing transmission history information indicating whether or not the terminal device has been sent to the care-of address,
Session information reception process for receiving session information distributed from the content distribution server;
The home address of the terminal device to which the received session information is not transmitted is read from the transmission history database, the care-of address associated with the read home address is read from the location management database, and the read care-of address is read. A session information transmission process for transmitting the received session information to:
A computer program that executes the process. A session information receiving unit that receives session information transmitted from the content distribution server at intervals;
A session information storage unit for storing the received session information;
A session information request receiving unit that receives a session information request for requesting the session information from a terminal device;
In response to the received session information request, the session information reading unit reads the session information from the session information storage unit, and transmits the read session information to the terminal device;
A session information transmitting apparatus comprising: In the session information transmitter according to claim 4,
It is determined whether or not the received session information and the session information stored in the session information storage unit are duplicated. If not, the received session information is written in the session information storage unit and duplicated. In the case where it does, it does not write the received session information in the session information storage unit, further comprises a write determination unit,
A session information transmitting apparatus characterized by the above. In a computer having a session information storage unit that stores session information transmitted from the content distribution server at intervals,
A session information receiving process for receiving the session information;
Writing the received session information into the session information storage unit;
A session information request receiving process for receiving a session information request for requesting the session information from a terminal device;
In response to the received session information request, a session information transmission process of reading the session information from the session information storage unit and transmitting the read session information to the terminal device;
A computer program that executes the process.

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