JP2006121464A - Data buffering method, data buffering device, and data buffering program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce consumption of a network bandwidth by data distribution when data distribution is performed in a wireless network.
A mobile terminal 104 detects a data buffering device 102 between a distribution server 101 and a home agent 103, and requests buffering. Upon receiving the request, the data buffering device 102 receives the data from the distribution server 101, stores the data in the storage device 105, and then directly transmits the data to which the stored address is assigned to the mobile terminal 104. The mobile terminal 104 manages the address of the storage device 105 that has been received. When the IP address of the mobile terminal 104 is updated, the address of the received storage device 105 is notified to the data buffering device 102. The data buffering device 102 retransmits data after the address.
[Selection] Figure 1

Description

  The present invention relates to a data buffering method, an apparatus thereof, and a program, and more particularly, to a data buffering method, an apparatus, and a program for improving content data delivery quality from a fixed node to a mobile node in a wireless network.

  In a wireless network using Mobile IPv4 (Internet Protocol version 4), when distributing data such as content from a distribution server (or proxy server) to a mobile terminal whose held IP (Internet Protocol) address changes every moment The distribution server first transmits an IP packet to a home agent holding a fixed IP address. Then, the home agent transfers the received IP packet to the mobile terminal. In order to realize this transfer, the home agent has its own IP address corresponding to each mobile terminal. That is, the home agent has a plurality of IP addresses and holds the correspondence between the IP addresses and the IP addresses of the mobile terminals. Then, the mobile terminal notifies the home agent of the IP address currently held as appropriate. At this time, if the IP address of the mobile terminal has changed, the home agent updates the IP address of the mobile terminal in the correspondence relationship. Since the home agent transfers the IP packet to the mobile terminal based on the correspondence relationship, even if the IP address held by the mobile terminal changes, the distribution server does not need to be aware of it and the IP address of the fixed home agent An IP packet may be transmitted by designating an address.

  Conversely, when distributing data from the mobile terminal to the distribution server (or proxy server), the mobile terminal first transmits an IP packet having the IP address of its own terminal as the source address to the home agent. Then, the home agent sets the home agent address as the source address of the received IP packet. Thereafter, the IP packet is transferred to the distribution server. Since the home agent sets the source address of the IP packet to the IP address of the home agent, the distribution server always recognizes that data has arrived from the home agent even if the IP address held by the mobile terminal changes can do. In addition, the IP packet having the home agent as the source address is not transmitted directly from the mobile terminal, but is transmitted via the home agent, resulting in ingress-filtering (sender IP address fraud check) in the middle of the router. IP packet discarding can be prevented.

  However, in Mobile IPv4, since the transfer is performed once via the home agent instead of directly, if the amount of data distributed from the distribution server or mobile terminal is large, useless network bandwidth is consumed, and the data distribution quality is reduced. Deteriorating problems (for example, IP packet congestion near the home agent) occur. Therefore, Non-Patent Document 1 describes a method for saving the consumed network bandwidth. In the method described in Non-Patent Document 1, another communication device (Correspondent Agent, Foreign Agent) is arranged adjacent to the distribution server (Correspondent Node) and the mobile terminal (Mobile Node).

  The Correspondent Agent manages a Binding Cache consisting of a combination of the IP address of the home agent and the mobile terminal instead of the home agent. Furthermore, all IP packets transmitted by the distribution server and all IP packets reaching the distribution server are intercepted. Here, if the destination address of the IP packet transmitted from the distribution server is not registered as the IP address of the home agent in the Binding Cache, the Correspondent Agent transfers the IP packet toward the destination of the IP packet. That is, an IP packet destined for a home agent that is not registered in the Binding Cache reaches the home agent. When receiving the IP packet, the home agent transmits a Binding Update request including information on the IP address held by the home agent and the mobile terminal to the Correspondent Agent. When the request is received, the Correspondent Agent creates a new Binding Cache entry consisting of a combination of the IP address held by the home agent and the mobile terminal. Further, even when the home agent is notified of the update of the IP address from the mobile terminal, the home agent transmits a Binding Update request to the Correspondent Agent and requests the Correspondent Agent to update the Binding Cache entry.

  When the destination address of the IP packet intercepted by the Correspondent Agent is registered as the IP address of the home agent in the Binding Cache entry, the Correspondent Agent does not transfer the IP packet to the home agent. Instead, it is encapsulated as an IP packet addressed to the IP address of the mobile terminal corresponding to the home agent in the Binding Cache entry (the source address is the IP address of the distribution server) and transferred to the mobile terminal. Before reaching the mobile terminal, the encapsulated packet is decapsulated at the Foreign Agent, and the original IP packet is restored. In this way, the Correspondent Agent directly transfers the IP packet from the distribution server to the mobile terminal, thereby realizing saving of the network bandwidth required for transfer from the distribution server to the home agent.

  The Foreign Agent manages the Tunneling Cache including the IP address information of the distribution server. Furthermore, all IP packets transmitted by the mobile terminal and all IP packets reaching the mobile terminal are intercepted. If the intercepted IP packet is an encapsulated IP packet destined for the mobile terminal, it is checked whether the source IP address (distribution server IP address) is registered in the Tunneling Cache and registered. If not, a new Tunneling Cache entry including information on the source IP address is created. Further, the IP packet is decapsulated to restore the original IP packet, and the restored IP packet is transferred to the mobile terminal.

When the intercepted IP packet is an IP packet transmitted from the mobile terminal, it is checked whether or not an entry in which the destination address of the IP packet is registered as the IP address of the distribution server exists in the Tunneling Cache. If not, the IP packet is transferred to the home agent as before. However, if present, the Foreign Agent does not forward the IP packet to the home agent. Instead, the IP packet is encapsulated in an IP packet having the IP address of the distribution server as the destination (the source address is the IP address of the mobile terminal), and then transferred to the distribution server. The IP packet is intercepted by the Correspondent Agent before reaching the distribution server, and decapsulated. The original IP packet is restored by decapsulation, and the restored IP packet reaches the distribution server. As described above, the Foreign Agent directly transfers the IP packet from the mobile terminal to the distribution server, thereby realizing saving of the network bandwidth required for the transfer from the mobile terminal to the home agent.
Chun-Hsin Wu, et al., "Bi-directional Route Optimization in Mobile IP over Wireless LAN", Proceedings of 56th IEEE Semiannual Vehicular Technology Conference, p.1168-1172, 2002

  In the method, it is assumed that the Correspondent Agent intercepts all packets transmitted from the distribution server and all packets reaching the distribution server. Therefore, the Corresponding Agent can be placed only in a location adjacent to the distribution server, specifically, in the local area network to which the distribution server belongs. As a result, in order to implement the method on any distribution server on the Internet, the distribution server holder prepares a Corresponding Agent dedicated to the distribution server for all distribution servers that provide distribution services on the Internet. It is necessary and requires a large equipment cost.

  In the above method, direct transmission of data from the distribution server to the mobile terminal is realized by encapsulating the IP packet by the Corresponding Agent adjacent to the distribution server. That is, an IP address other than the home agent is set as the destination address of the IP packet transmitted from the distribution server. Therefore, if there is a firewall or VPN (Virtual Private Network) gateway held by the vendor holding the distribution server between the distribution server (and the corresponding Correspondent Agent) and the Foreign Agent, These will not work properly. For example, it is assumed that there is a firewall that rejects all IP packets distributed from the distribution server except for IP packets addressed to the home agent. In this case, when encapsulation is performed, all IP packets transmitted from the distribution server have an IP address other than the home agent as a destination address, and therefore are all rejected. Further, it is assumed that there is a VPN gateway that forms a VPN with the mobile terminal. In this case, the VPN gateway needs to detect an IP packet addressed to the home agent and encrypt the IP packet. However, once encapsulation is performed, the IP packet transmitted from the distribution server has an IP address other than the home agent as the transmission destination address, and thus is not encrypted.

  Further, in the above method, when the IP address of the mobile terminal is updated, the home agent sends a Binding Update request to the Correspondent Agent after notifying the home agent of the update of the IP address. Until this Binding Update request arrives, the Corresponding Agent continues to send the encapsulated packet to the IP address previously held by the mobile terminal. That is, when the IP address of the mobile terminal is updated, all IP packets sent by the distribution server are discarded without reaching the mobile terminal between the time when the IP address is updated and the time when the Binding Update request reaches the Corresponding Agent. As a result, the data distribution quality is degraded.

  In view of the above problems, an object of the present invention is to reduce consumption of a network band due to data distribution when data distribution is performed in a wireless network.

  In the present invention for solving the above problems, a data buffering device is arranged between the server (distribution server) and the relay device (home agent). This data buffering device is not dedicated to a specific server and can buffer data (IP packets) of any server. Further, the data buffering device can be arranged at an arbitrary position on the network.

  When the data buffering device receives data from the server, the data buffering device transmits a presence notification message to the relay device set as the transfer destination address of the data. This presence notification message includes the network address of the data buffering device. The relay device transfers the received presence notification message to the terminal (mobile terminal). Upon receiving the presence notification message, the terminal recognizes the existence of a data buffering device that can buffer the data set by the relay device as the transfer destination address, and sends a buffering start request message to the data buffering device. Issue. The data buffering device that has received the buffering start request message reserves a storage area for the terminal in the storage means provided in the data buffering device. Further, the terminal issues a transfer start request message including the currently held network address to the data buffering device. Thereafter, the data buffering device intercepts all data for which the relay device is set as the transfer destination address. Then, instead of transferring the data to the relay device, the data is stored in the secured storage area. Furthermore, the address information of the storage area in which the data is stored is added to the data and transmitted directly to the terminal (without going through the relay device).

  By receiving the data including the address information, the terminal can recognize to which address information the data stored in the storage device of the data buffering device has been received by the terminal. Further, when the network address held by the terminal is updated, the terminal again transmits a transfer start request message including the updated network information to the data buffering device. This transfer start request message can include address information of the storage area, and redistribution of all data stored in the storage area up to now with the data existing after the address information is combined with the data buffering device. Can be requested.

According to the present invention, first, the data buffering device need not be adjacent to the server. The data buffering device does not need to intercept all the data transmitted by the server, but may simply intercept the data transmitted by a predetermined server and set as the transfer destination address. Further, the transfer start request message to the terminal may be transmitted by setting the data buffering device as the transfer destination address instead of the server. Therefore, the data buffering device can be placed on any network that exists between the server and the relay device.
Further, according to the present invention, even if the network address held by the terminal is updated, the data buffering device can retransmit data by issuing a transfer start request message including address information in the storage device. Can be requested.

  According to the present invention, when data distribution is performed in a wireless network, it is possible to reduce network bandwidth consumption by using network equipment (data buffering device) that can be arranged at an arbitrary position on the network.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

≪System configuration and overview≫
1 and 2 show the configuration and outline of a wireless network system according to an embodiment of the present invention. As shown in each figure, a wireless network system includes a distribution server device 101 (hereinafter, and distribution server 101 in the drawings), a data buffering device 102, a home agent device 103 (hereinafter, and in the drawings, home agent 103), and a mobile terminal. 104 is comprised. In addition, the data buffering device 102 has a storage device 105 built-in or externally connected.
The distribution server 101, the data buffering device 102, and the home agent 103 are connected via a wired network. The data buffering device 102 and the mobile terminal 104 and the home agent 103 and the mobile terminal 104 are connected via a wireless network, respectively.

  The distribution server 101 is a server that distributes data such as content to each mobile terminal 104, and is realized by, for example, a PC (Personal Computer) server. The distribution server 101 may be a proxy server that relays access to the Internet, and may receive data from the mobile terminal 104. The mobile terminal 104 is a wireless terminal that receives data such as content from the distribution server 101 and displays it to the user, and is realized by, for example, a mobile phone or a notebook PC. The mobile terminal 104 may transmit data to the distribution server 101. The home agent 103 is arranged between the distribution server 101 and each mobile terminal 104, absorbs the IP address of the mobile terminal 104 that changes every moment, and indicates a fixed address unique to the mobile terminal 104 to the distribution server 101. Thus, the relay apparatus relays the IP packet between the distribution server 101 and each mobile terminal 104. For this reason, the home agent 103 holds a binding management table 701 (see FIG. 7) for managing the correspondence between the home agent address and the mobile terminal address (details will be described later). Further, the data buffering device 102 is arranged on a route between the distribution server 101 and the home agent 103, and realizes transfer of IP packets between the distribution server 101 and each mobile terminal 104 without the intervention of the home agent 103. Device. The data buffering device 102 temporarily stores the relayed IP packet in the storage device 105.

  Here, FIG. 1 and FIG. 2 show one distribution server 101, one data buffering device 102, one home agent 103, and one mobile terminal 104. In practice, each type of node (network device) ). In particular, it is desirable that a large number of data buffering devices 102 are arranged on the path between the distribution server 101 and the home agent 103. When the data buffering apparatus 102 receives an IP packet transmitted from the distribution server 101, the data buffering method according to the embodiment of the present invention is performed. When the agent 103 receives the data, conventional data transfer via the home agent 103 is performed.

  FIG. 1 shows an outline of the configuration and operation procedure of a wireless network system when an IP packet (including messages such as various requests and notifications, the same applies hereinafter) is transmitted from a distribution server to a mobile terminal. In the wireless network system of FIG. 1, IP packet distribution from the distribution server 101 to the mobile terminal 104 is optimized using the data buffering device 102. The mobile terminal 104 transmits a binding start / stop request to the home agent 103 in order to transfer various requests and notifications with the data buffering device 102. With this binding start / stop request, the home agent 103 recognizes the IP address currently held by the mobile terminal 104 and realizes various notifications and transfer of requests.

  When the data buffering device 102 receives the IP packet from the distribution server 101, the data buffering device 102 transmits its own device presence notification including the IP addresses of the distribution server 101 and the data buffering device 102 to the home agent 103. This presence notification reaches the mobile terminal 104 via the home agent 103. Upon receiving the presence notification, the mobile terminal 104 detects the presence of the data buffering device 102 capable of buffering the IP packet addressed to the home agent 103 from the distribution server 101, and notifies the home agent of the data buffering device 102. A buffering start request is issued via 103. When the data buffering device 102 receives the buffering start request, the data buffering device 102 secures a storage area for the mobile terminal 104 that is the request source in the storage device 105 that the device itself has. Further, the mobile terminal 104 issues a transfer start request including the currently held IP address information to the data buffering apparatus 102.

  Thereafter, the data buffering device 102 intercepts all IP packets from the distribution server 101 to the home agent 103 corresponding to the secured storage area. Then, instead of transferring the IP packet to the home agent 103, the IP packet is stored in a storage area secured in the storage device 105. Furthermore, the address information of the storage area in which the IP packet is stored is attached to the IP packet and transmitted directly to the mobile terminal 104 (without going through the home agent 103). As a result, the network bandwidth consumed for data distribution can be reduced.

The mobile terminal 104 receives up to the IP packet stored in which address information in the storage device 105 of the data buffering device 102 by receiving the IP packet including the address information of the storage area. Can be recognized. When the IP address held by the mobile terminal 104 is updated, the mobile terminal 104 transmits a transfer start request including the updated IP address information to the data buffering apparatus 102 again. This transfer start request can include the address information in the storage device 105 of the data buffering device 102, and all the data stored in the storage device 105 up to now with IP packets existing after the address information. Redistribution can be requested in conjunction with the data buffering device 102. According to this, the mobile terminal 104 can receive the IP packet from the distribution server 101 without omission even if the held IP address is updated.
In addition, when the mobile terminal 104 shuts down, the mobile terminal 104 transmits a transfer stop request and a buffering stop request to the data buffering device 102 via the home agent 103 to stop the transfer process or store the storage device. The data buffering apparatus 102 is requested to release the storage area secured in 105.

  FIG. 2 shows an outline of a configuration and an operation procedure of the wireless network system when an IP packet is transmitted from the mobile terminal to the distribution server. In the wireless network system of FIG. 2, IP packet delivery from the mobile terminal 104 to the delivery server 101 is optimized using the data buffering device 102. As described in FIG. 1, the mobile terminal 104 transmits and receives various notifications and requests between the mobile terminal 104 and the data buffering device 102 by transmitting a binding start / stop request to the home agent 103. is doing.

  The mobile terminal 104 transmits a presence notification transmission request via the home agent 103 in order to detect the presence of the data buffering device 102 that can be used for optimization of IP packet transmission to the distribution server 101. This presence notification transmission request is assumed to be received by the data buffering apparatus 102. When receiving the presence notification transmission request, the data buffering device 102 transmits a presence notification to the mobile terminal 104 via the home agent 103 instead of transferring the request to the distribution server 101. Since the IP address information of the data buffering device 102 is stored in the presence notification, the mobile terminal 104 can uniquely identify the data buffering device 102. When the distribution server 101 or another node receives the presence notification transmission request, it determines that the message cannot be processed and discards the request.

  Thereafter, when the mobile terminal 104 transmits an IP packet to the distribution server 101, the mobile terminal 104 does not transmit the IP packet to the home agent 103. Instead, an IP packet encapsulated in the data buffering device 102 is transmitted. Then, the data buffering device 102 decapsulates the received IP packet to restore the original IP packet (the source address is the IP address of the home agent 103), and transfers it to the distribution server 101. Since the path between the data buffering device 102 and the distribution server 101 is a part of the path from the home agent 103 to the distribution server 101, the restored IP packet is ingress-filtering (incorrect transfer source address check). There is no possibility of being destroyed by. In addition, it is possible to reduce the consumed network bandwidth by IP packet transmission not via the home agent 103.

  FIG. 3 is a diagram showing a hardware configuration of the data buffering apparatus according to the embodiment of the present invention. The data buffering device 102 includes a CPU 301, a memory controller 302, a memory 303, a storage device controller 304, a storage device 105, and a network controller 305.

  The CPU 301 and the memory 303 are connected via the memory controller 302. A program (including a data buffering program) for controlling the operation of the data buffering apparatus 102 is stored in the memory 303. The CPU 301 executes the program while reading it from the memory 303 via the memory controller 302. The CPU 301 and the storage device 105 are connected via a storage device controller 304. Data existing on the memory 303 can be transferred to the storage device 105, and data existing on the storage device 105 can be transferred to the memory 303 by a program that controls the storage device controller 304. The CPU 301 is connected to the external network 306 via the network controller 305. Data existing on the memory 303 can be transferred to the external network 306, and data received via the external network 306 can be transferred to the memory 303 by a program that controls the network controller 305. The data buffering device 102 uses the hardware to send and receive messages such as various notifications and requests via the external network 306, store data received from the external network 306 in the storage device 105, and the storage device 105. It becomes possible to transmit data read from the external network 306.

<< Message structure >>
FIG. 4 is a diagram showing the format of various notifications and requests (messages) transmitted and received between the data buffering device and the mobile terminal. The basic configuration of the format includes a transmission source address, a transmission destination address, a code indicating a message type, and data set in correspondence with the code when viewed from the data buffering device 102. The home agent address is a fixed address corresponding to each mobile terminal 104. In other words, the mobile terminal 104 can be specified by the home agent address.

The presence notification 401 includes a buffering device address (IP address of the data buffering device 102), a home agent address (IP address of the home agent 103), a presence notification code (a code indicating that the message is a presence notification), and a distribution server. An address (IP address of the distribution server 101) is included.
The presence notification transmission request 402 includes a home agent address, a distribution server address, and a transmission request code (a code indicating that the message is a presence notification transmission request).

The buffering start request 403 includes a home agent address, a buffering device address, a start request code (a code indicating that the message is a buffering start request), a distribution server address, and a buffering capacity (request allocation capacity of the storage device 105). It is comprised including.
The buffering stop request 404 includes a home agent address, a buffering device address, a stop request code (a code indicating that the message is a buffering stop request), and a distribution server address.

The transfer start request 405 includes a home agent address, a buffering device address, a transfer start code (a code indicating that the message is a transfer start request), a distribution server address, and a mobile terminal address (IP address of the mobile terminal 104 serving as a transfer destination). ) And transfer start address information (requesting retransmission of an IP packet that arrives after the IP packet stored at the address in the storage device 105).
The transfer stop request 406 includes a home agent address, a buffering device address, a transfer stop code (a code indicating that the message is a transfer stop request), a distribution server address, and a mobile terminal address (the current IP address of the mobile terminal 104). Consists of including.

FIG. 5 is a diagram showing a format of various requests (messages) transmitted and received between the home agent and the mobile terminal.
The binding start request 501 includes a mobile terminal address (IP address currently held by the mobile terminal 104), a home agent address (IP address of the home agent 103), and an old mobile terminal address (IP previously held by the mobile terminal 104). Address).
The binding stop request 502 includes a mobile terminal address (IP address currently held by the mobile terminal 104) and a home agent address (IP address of the home agent 103).

<< Table data structure >>
FIG. 6 is a diagram illustrating a data structure of a storage device management table held by the data buffering device.
The storage device management table 601 includes a distribution server address, a home agent address, a mobile terminal address, a storage device allocation area start address, a storage device allocation area size, and a write position.
Each entry means that an IP packet addressed to the home agent 103 from the distribution server 101 is transmitted to the IP address of the mobile terminal 104 registered corresponding to the combination of the distribution server 101 and the home agent 103. . It also means that the data is stored in the storage area inside the storage device 105 specified by the storage device allocation area start address and the storage apparatus allocation area size. The writing position manages to which position in the storage device 105 the writing has been completed.

  FIG. 7 is a diagram showing the data structure of the binding management table held by the home agent. The binding management table 701 includes a home agent address and a mobile terminal address, and manages the correspondence between the IP address of the home agent 103 and the IP address currently held by the mobile terminal 104. Here, the home agent 103 is physically one device, but has a plurality of IP addresses. Each of these IP addresses uniquely corresponds to the IP address of the mobile terminal 104. The binding management table 701 holds the correspondence. In the binding management table 701, the IP address reserved by the home agent 103 at that time is set in the home agent address field, but when the corresponding mobile terminal address is not set, the IP address in the mobile terminal address field is set. NULL indicating an invalid state is set.

FIG. 8 is a diagram illustrating a data structure of the reception management table held by the mobile terminal. The reception management table 801 includes fields of a distribution server address, a transmission data buffering device address, a reception data buffering device address, and received address information.
Each entry uses the data buffering device 102 specified in each field of the transmission data buffering device address and the reception data buffering device address when the mobile terminal 104 communicates with the distribution server 101. means. In addition, the received address information field manages which address in the storage device 105 held by the data buffering device 102 stores the last IP packet received from the distribution server 101.

≪System operation≫
The operation of the wireless network system according to the embodiment of the present invention will be described with reference to the flowcharts of FIGS. 9 to 24 (see FIGS. 1 to 8 as appropriate). Hereinafter, each operation will be described in the order of the home agent 103, the data buffering device 102, and the mobile terminal 104.

<Home agent operation>
9 to 12 are flowcharts showing the operation procedure of the home agent according to the embodiment of the present invention. The home agent 103 starts operation when receiving an IP packet from the data buffering device 102, receiving an IP packet from the mobile terminal 104, or receiving a binding start / stop request from the mobile terminal 104. Hereinafter, an operation procedure of the home agent 103 in each case will be described.

  FIG. 9 is a flowchart showing an operation procedure of the home agent when an IP packet is received from the data buffering device. First, the home agent 103 receives an IP packet from the data buffering device 102 (step S901). Then, by searching the binding management table 701 on the condition of the home agent address in the received IP packet, a mobile terminal address corresponding to the home agent address is obtained, and the obtained mobile terminal address (IP address) is obtained. On the other hand, the received IP packet is transferred (step S902).

  FIG. 10 is a flowchart showing an operation procedure of the home agent when an IP packet is received from the mobile terminal. First, the home agent 103 receives an IP packet from the mobile terminal 104 (step S1001). Next, the IP address held by the home agent 103 is set as the source address of the received IP packet (step S1002). At this time, by referring to the binding management table 701, the home agent address corresponding to the mobile terminal address that is the transmission source address of the received IP packet is acquired, and the acquired home agent address is used as the new transmission source of the IP packet. Address. The home agent 103 transmits the IP packet to the destination IP address (step S1003).

  FIG. 11 is a flowchart showing an operation procedure of the home agent when a binding start request is received from the mobile terminal. First, the home agent 103 receives a binding start request 501 from the mobile terminal 104 (step S1101). Then, after searching whether or not the mobile terminal address field of the binding management table 701 matches the value of the old mobile terminal address field of the binding start request 501, if it matches, the mobile terminal address field of the binding start request 501 The value is set in the mobile terminal address field of the binding management table 701 (step S1102).

  FIG. 12 is a flowchart showing an operation procedure of the home agent when a binding stop request is received from the mobile terminal. First, the home agent 103 receives a binding stop request 502 from the mobile terminal 104 (step S1201). Then, the mobile terminal address field having the value of the mobile terminal address in the binding stop request 502 is invalidated in the binding management table 701 (step S1202). Specifically, NULL indicating an invalid state is set in the field.

<Operation of data buffering device>
13 to 19 are flowcharts showing an operation procedure of the data buffering apparatus according to the embodiment of the present invention. The data buffering device 102 receives a buffering start / stop request from the mobile terminal 104 via the home agent 103, receives a transfer start / stop request, receives a presence notification transmission request, and The operation starts when an IP packet is received from the distribution server 101 or the mobile terminal 104. Hereinafter, an operation procedure of the data buffering apparatus 102 in each case will be described.

  FIG. 13 is a flowchart showing an operation procedure when the data buffering apparatus receives a buffering start request. First, the data buffering apparatus 102 receives a buffering start request 403 from the mobile terminal 104 via the home agent 103 (step S1301). Next, a storage area (storage device allocation area) for the capacity specified in the buffering capacity field of the buffering start request 403 is secured in the storage device 105 (step S1302). Then, the storage device management table 601 is initialized (step S1303). Specifically, the distribution server address and the home agent address stored in the buffering start request 403 are set in the distribution server address field and the home agent address field. The mobile terminal address field is not initialized. In the storage device allocation area start address field, the value of the start address of the storage apparatus allocation area secured previously is set. A buffering capacity value of the buffering start request 403 is set in the storage area allocation size field. In the write position field, the same value as the storage device allocation area start address field is set.

  FIG. 14 is a flowchart showing an operation procedure when the data buffering apparatus receives a buffering stop request. First, the data buffering apparatus 102 receives a buffering stop request 404 from the mobile terminal 104 via the home agent 103 (step S1401). Next, the data buffering device 102 releases the storage device allocation area reserved for the distribution server and home agent specified by the buffering stop request 404 (step S1402). Then, the entry in the storage device management table 601 for the distribution server address and home agent address specified in the buffering stop request 404 is deleted from the storage device management table 601 (step S1403).

  FIG. 15 is a flowchart showing an operation procedure when the data buffering apparatus receives a transfer start request. First, the data buffering apparatus 102 receives a transfer start request 405 from the mobile terminal 104 via the home agent 103 (step S1501). Next, the storage device management table 601 is searched for an entry for the distribution server address and home agent address specified by the transfer start request 405. Then, the value of the mobile terminal address field of the matched entry is updated to the value of the mobile terminal address field included in the transfer start request 405 (step S1502). This is to update to the latest IP address in order to correspond to the IP address of the mobile terminal 104 that changes from moment to moment. Subsequently, the data stored in the storage area from the address next to the transfer start address information specified by the transfer start request 405 to the address specified by the write position field of the entry in the searched storage device management table 601 To generate an IP packet. Specifically, the address information of the storage device 105 and the IP header (the data buffering device 102 is the transmission source address and the mobile terminal 104 is the transmission destination address) are added to each data (IP packet received from the distribution server 101). . Then, the generated IP packet is transmitted to the mobile terminal 104 (step S1503).

  FIG. 16 is a flowchart showing an operation procedure when the data buffering apparatus receives a transfer stop request. First, the data buffering apparatus 102 receives a transfer stop request 406 from the mobile terminal 104 via the home agent 103 (step S1601). Then, the entry of the storage device management table 601 is searched on the condition of the home agent address and distribution server address of the transfer stop request 406, and the value of the mobile terminal address field of the matched entry is invalidated (step S1602). In order to invalidate the value of the field, for example, NULL is set in the field.

  FIG. 17 is a flowchart showing an operation procedure when the data buffering apparatus receives the presence notification transmission request. First, the data buffering apparatus 102 receives the presence notification transmission request 402 from the mobile terminal 104 via the home agent 103 (step S1701). Then, in order to notify the presence of the own device, the presence notification 401 is transmitted to the home agent address stored in the presence notification transmission request 402 (step S1702). The values of the home agent address field and distribution server address field set in the presence notification 401 are copied from the received presence notification transmission request 402. The value of the IP address of the own device is set in the buffering device address field. A code value indicating that the message is a presence notification is set in the presence notification code field.

  FIG. 18 is a flowchart showing an operation procedure when the data buffering apparatus receives an IP packet from the distribution server. First, the data buffering apparatus 102 receives an IP packet from the distribution server 101 (step S1801). Next, the transmission source address of the received IP packet is set in the distribution server address field, and whether or not the entry in which the transmission destination address is set in the home agent address field is registered in the storage device management table 601 is searched. A check is made (step S1802).

  If not registered (NO in step S1802), the data buffering apparatus 102 transmits the presence notification 401 to the transmission destination address of the IP packet (that is, the home agent 103) (step S1803). The presence notification 401 reaches the mobile terminal 104 via the home agent 103. In the buffering device address field of the presence notification 401, the IP address of the own device is set. In the home agent address field, the transmission destination address of the received IP packet is set. A code value indicating that the message is a presence notification is set in the presence notification code field. In the distribution server address field, the transmission source address of the received IP packet is set. Then, the received IP packet is transmitted to the transmission destination address (ie, home agent 103) (step S1804). Here, since the response (buffering start request or transfer start request) from the mobile terminal 104 to the transmission of the presence notification 401 (step S1803) has not been received, the IP packet is transmitted to the home agent 103.

  If registered in step S1802 (YES in step S1802), the data buffering device 102 writes the received IP packet in the storage device 105 (step S1805). The start address of the storage area in the storage device 105 to be written is determined according to the value of the write position field of the entry in the storage device management table 601 searched in step S1802. Thereafter, the value of the write position field in the storage device management table 601 is updated by the written data size (step S1806). Next, the IP packet is read from the storage device 105, and the address information (the top address of the storage area in the storage device 105 written in step S1805) and the IP header (the IP address of the data buffering device 102 are the source) are read into the IP packet. Address, and the IP address of the mobile terminal 104 is a destination address) (step S1807). Here, the IP address of the mobile terminal 104 follows the value of the mobile terminal address field of the entry of the storage device management table 601 searched in step S1802. Then, an IP packet is transmitted to the mobile terminal address (step S1808).

  In this way, the data buffering device 102 adds an IP header with the IP address of the mobile terminal 104 as the transmission destination address to the received IP packet (the IP address of the home agent 103 is the transmission destination address). Thus, the IP packet can be directly transmitted to the mobile terminal 104 without going through the home agent 103. According to this, even if a large amount of data is transferred, the consumption of the network bandwidth can be suppressed.

  FIG. 19 is a flowchart showing an operation procedure when the data buffering apparatus receives an IP packet from a mobile terminal. First, the data buffering apparatus 102 receives an IP packet from the mobile terminal 104 (step S1901). Next, the head IP header (the source address is the mobile terminal 104 and the destination address is the data buffering device 103) is deleted from the received IP packet (step S1902). As a result, the original IP packet can be restored (extracted). Then, the restored IP packet is transmitted to the transmission destination address (that is, the distribution server 101) described in the original IP header in the IP packet (step S1903).

<Mobile terminal operation>
20 to 24 are flowcharts showing an operation procedure of the mobile terminal according to the embodiment of the present invention. When the mobile terminal 104 receives the presence notification from the data buffering device 102, when the system starts / shuts down, when the IP address update is detected, when the IP packet is received from the data buffering device 102, the mobile terminal 104 The operation starts when the above application issues an IP packet transmission request. Hereinafter, an operation procedure of the mobile terminal 104 in each case will be described.

  FIG. 20 is a flowchart showing an operation procedure when the mobile terminal receives the presence notification from the data buffering apparatus. First, the mobile terminal 104 receives the presence notification 401 from the data buffering apparatus 102 via the home agent 103 (step S2001). The buffering device address of the presence notification 401 is a received data buffering device address for the mobile terminal 104. Next, whether or not the entry in which the distribution server address specified by the presence notification 401 is set in the distribution server address field is registered in the reception management table 801 is searched and checked (step S2002). Here, “registered” means that both values of the transmission data buffering device address and the reception data buffering device address are set in the reception management table 801 corresponding to the distribution server address. If registered (YES in step S2002), the process ends.

  If not registered (NO in step S2002), a presence notification transmission request 402 is transmitted to the distribution server address specified by the presence notification 401 in order to acquire a transmission data buffering device address (step S2003). . In the home agent address field of the presence notification transmission request 402, the IP address of the home agent 103 corresponding to the own terminal is set. As the home agent address, a fixed home agent address previously set in the mobile terminal 104 by the user is used (hereinafter the same). In the distribution server address field, the value of the distribution server address stored in the presence notification 401 is set. In the transmission request code field, a code value indicating that the message is a presence notification transmission request is set. Then, the presence notification 401 which is a response from the data buffering device 402 to the transmitted presence notification transmission request 402 is received (step S2004). At this time, the buffering device address (for transmission) of the received presence notification 401 is independent from the buffering device address (for reception) stored in the presence notification 401 received in step S2001. Sometimes, it happens to be the same.

  Subsequently, a new entry is created in the reception management table 801 (step S2005). In the distribution server address field of the new entry, the value of the distribution server address stored in the presence notification 401 received in step S2001 is set. In the transmission data buffering device address field, the value of the buffering device address stored in the presence notification 401 received in step S2004 is set. In the received data buffering device address field, the value of the buffering device address stored in the presence notification 401 received in step S2001 is set. In the received address information field, NULL indicating an invalid state is set.

  Next, a buffering start request 403 is transmitted to the data buffering device 102 specified by the received data buffering device address field of the reception management table 801 (step S2006). In the home agent address field of the buffering start request 403, the IP address of the home agent 103 corresponding to the own terminal is set. In the buffering device address field, the value of the reception data buffering device address field of the reception management table 801 is set. A code value indicating that the message is a presence notification transmission request is set in the start request code field. In the distribution server address field, the value of the distribution server address stored in the presence notification 401 received in step S2001 is set. A value set in advance in the mobile terminal 104 is set in the buffering capacity field. The value of the buffering capacity for each mobile terminal 104 is arbitrarily set within a predetermined range by the user, or is set according to the fee paid by the user for the service by the data buffering service provider. Can be considered.

  Further, a transfer start request 405 is transmitted to the data buffering device 102 specified by the received data buffering device address field of the reception management table 801 (step S2007). In the home agent address field of the transfer start request 405, the IP address of the home agent 103 corresponding to the own terminal is set. In the buffering device address field, the value of the reception data buffering device address field of the reception management table 801 is set. A code value indicating that the message is a transfer start request is set in the transfer start code field. In the distribution server address field, the value of the distribution server address stored in the presence notification 401 received in step S2001 is set. An IP address currently held by the own terminal is set in the mobile terminal address field. In the transfer start address information field, NULL indicating an invalid state is set. Note that the data buffering apparatus 102 does not transmit an IP packet to the mobile terminal 104 in step S1503 when receiving a transfer start request in which NULL is stored in the transfer start address information field.

  FIG. 21 is a flowchart showing an operation procedure when the mobile terminal detects its own system start or IP address update. First, the mobile terminal 104 detects system start or IP address update (step S2101). Next, the mobile terminal 104 transmits a binding start request 501 to the home agent 103 (step S2102). In the mobile terminal address field of the binding start request 501, an IP address currently held by the own terminal is set. In the home agent address field, the IP address of the home agent 103 corresponding to the own terminal is set. In the old mobile terminal address field, an IP address held by the own terminal before updating the IP address (NULL indicating an invalid state at the time of system start) is set.

  Then, for all entries registered in the reception management table 801, a transfer start request 405 is transmitted to the data buffering device 102 specified by the received data buffering device field of each entry (step S2103). . However, since the reception management table 801 is empty when the system is started, nothing is done. In the home agent address field of the transfer start request 405, the IP address of the home agent 103 corresponding to the own terminal is set. In the buffering device address field, the value of the reception data buffering device address field of the reception management table 801 is set. A code value indicating that the message is a transfer start request is set in the transfer start code field. In the distribution server address field, the value of the distribution server address field of the entry of the reception management table 801 is set. In the mobile terminal address field, an IP address currently held by the own terminal is set. In the transfer start address information field, the value of the received address information field of the entry of the reception management table 801 is set.

  FIG. 22 is a flowchart showing an operation procedure when the mobile terminal performs system shutdown. First, the mobile terminal 104 detects that its own terminal is shut down (step S2201). This means that the system shutdown process is detected by the user turning off the power of the mobile terminal 104 as a trigger, and the system shutdown processing program starts to operate. This processing program may be started when a system shutdown is detected by polling of the main routine, or may be executed in an interrupt routine corresponding to an interrupt due to the occurrence of a system shutdown.

  Next, for all entries in the reception management table 801, a transfer stop request 406 and a buffering stop request 404 are transmitted to the data buffering device 102 specified by the received data buffering device address (step S2202). In the home agent address field of the transfer stop request 406, the IP address of the home agent corresponding to the own terminal is set. In the buffering device address field, the value of the received data buffering device address of each entry of the reception management table 801 is set. A code value indicating that the message is a transfer stop request is set in the transfer stop code field. In the distribution server address field, the value of the distribution server address field of each entry is set. An IP address held by the own terminal is set in the mobile terminal address field. Similarly, the home agent address field, buffering device address field, stop request code field, and distribution server address field of the buffering stop request 404 are set in the same manner.

  Furthermore, the mobile terminal 104 transmits a binding stop request 502 to the home agent 103 (step S2203). In the mobile terminal address field of the binding stop request 502, the IP address held by the own terminal is set. In the home agent address field, the IP address of the home agent 103 corresponding to the own terminal is set.

  As a result, it is possible to prevent the data buffering device 102 and the home agent 103 from transferring useless IP packets even after the mobile terminal 104 has shut down the system.

  FIG. 23 is a flowchart showing an operation procedure when the mobile terminal receives an IP packet from the data buffering apparatus. First, the mobile terminal 104 receives an IP packet from the data buffering apparatus 102 via the home agent 103 (step S2301). Next, a corresponding entry in the reception management table 801 is detected. In the corresponding entry, the source address of the received IP packet matches the received data buffering device address field, and the source address of the IP packet encapsulated in the received IP packet is the distribution server address field. Detect by matching. Then, the received address information field of the entry is updated with the address information included in the received IP packet (step S2302). Then, the IP header and address information added to the received IP packet are deleted, and the original IP packet transmitted by the distribution server 101 is restored (extracted) (step S2303).

  FIG. 24 is a flowchart showing an operation procedure of the mobile terminal when an application on the mobile terminal issues an IP packet transmission request. First, an application on the mobile terminal 104 issues an IP packet transmission request (step S2401). Next, it is checked whether an entry corresponding to the IP packet requested to be transmitted has been registered in the reception management table 801 (step S2402). The entry has a value in the distribution server address field that matches the transmission destination address of the IP packet requested to be transmitted.

  If registered (YES in step S2402), an IP header is added to the IP packet requested to be transmitted from the application. The IP address currently held by the terminal itself is set as the source address of the IP header to be added. In the transmission destination address, the value of the transmission data buffering device address field of the entry whose registration is detected in step S2402 is set. Then, the IP packet is transmitted to the data buffering device 102 specified by the transmission data buffering device address field (step S2403). If not registered (NO in step S2402), the mobile terminal 104 transmits the IP packet requested to be transmitted to the home agent 103 (step S2404).

  As described above, when an IP packet is transmitted from the mobile terminal 104 to the distribution server 101, if the transmission data buffering device address corresponding to the distribution server 101 of the transmission destination is registered, the IP address is transmitted without going through the home agent 103. The packet can be transmitted to the distribution server 101 via the data buffering device 102. According to this, even if a large amount of data is transferred, it is possible to suppress the consumption of the network bandwidth by using the network equipment (data buffering device) that can be arranged at an arbitrary position on the network. As a result, it is possible to share network equipment among a plurality of distribution servers, or to cooperate with a firewall or a VPN gateway. Further, it is possible to prevent data loss when updating the network address of the mobile terminal.

  Although the embodiment of the present invention has been described above, the program executed in each node shown in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system. By executing, the wireless network system according to the embodiment of the present invention is realized. The program may be distributed via a network.

  An example of the preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.

It is a figure which shows the structure and outline | summary of the radio | wireless network system which concerns on embodiment of this invention. In particular, a case where an IP packet is transmitted from a distribution server to a mobile terminal will be described. It is a figure which shows the structure and outline | summary of the radio | wireless network system which concerns on embodiment of this invention. In particular, a case where an IP packet is transmitted from a mobile terminal to a distribution server will be described. It is a figure which shows the hardware constitutions of the data buffering apparatus which concerns on embodiment of this invention. It is a figure which shows the format of various notifications and requests | requirements transmitted / received between the data buffering apparatus which concerns on embodiment of this invention, and a mobile terminal. It is a figure which shows the format of the various requests | requirements transmitted / received between the home agent which concerns on embodiment of this invention, and a mobile terminal. It is a figure which shows the data structure of the memory | storage device management table which the data buffering apparatus which concerns on embodiment of this invention hold | maintains. It is a figure which shows the data structure of the binding management table which the home agent which concerns on embodiment of this invention hold | maintains. It is a figure which shows the data structure of the reception management table which the mobile terminal which concerns on embodiment of this invention hold | maintains. It is a flowchart which shows the operation | movement procedure of the home agent which concerns on embodiment of this invention. In particular, the operation when an IP packet is received from the data buffering device is shown. It is a flowchart which shows the operation | movement procedure of the home agent which concerns on embodiment of this invention. In particular, an operation when an IP packet is received from a mobile terminal is shown. It is a flowchart which shows the operation | movement procedure of the home agent which concerns on embodiment of this invention. In particular, the operation when a binding start request is received from a mobile terminal is shown. It is a flowchart which shows the operation | movement procedure of the home agent which concerns on embodiment of this invention. In particular, the operation when a binding stop request is received from a mobile terminal is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when a buffering start request is received is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when a buffering stop request is received is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when a transfer start request is received is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when a transfer stop request is received is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when a presence notification transmission request is received is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, the operation when an IP packet is received from a distribution server is shown. It is a flowchart which shows the operation | movement procedure of the data buffering apparatus which concerns on embodiment of this invention. In particular, an operation when an IP packet is received from a mobile terminal is shown. It is a flowchart which shows the operation | movement procedure of the mobile terminal which concerns on embodiment of this invention. In particular, the operation when a presence notification is received from the data buffering device is shown. It is a flowchart which shows the operation | movement procedure of the mobile terminal which concerns on embodiment of this invention. In particular, the operation when a system start or IP address update is detected is shown. It is a flowchart which shows the operation | movement procedure of the mobile terminal which concerns on embodiment of this invention. In particular, the operation when the system is shut down is shown. It is a flowchart which shows the operation | movement procedure of the mobile terminal which concerns on embodiment of this invention. In particular, the operation when an IP packet is received from the data buffering device is shown. It is a flowchart which shows the operation | movement procedure of the mobile terminal which concerns on embodiment of this invention. In particular, an operation when an application on a mobile terminal issues an IP packet transmission request is shown.

Explanation of symbols

101 Distribution server (server)
102 Data buffering device 103 Home agent (relay device)
104 Mobile terminal (terminal)
105 Storage device (storage means)

Claims (9)

A server and a plurality of terminals that mutually transmit and receive predetermined data;
A relay that is arranged between the server and the terminal, maintains a correspondence relationship between the network address of one or more own devices and the network address of each terminal, and relays data between the server and the terminal according to the correspondence relationship Equipment,
In a wireless network system having a communication method in which, when the server transmits data to the terminal, the network address of the relay device corresponding to the terminal is set as a transfer destination address.
Furthermore, a data buffering method by a data buffering device that is arranged between the server and the relay device and realizes data transfer between the server and the terminal without going through the relay device,
When receiving data from the server to the terminal, transmitting a presence notification message for notifying the terminal of the presence of the device that receives data from the server via the relay device;
When a buffering start request message for requesting start of data buffering is received from the terminal that has received the presence notification message via the relay device, the terminal from the server in the storage means provided in the own device Securing a storage area for buffering data to
Storing the received data from the server to the terminal in the reserved storage area;
When a transfer start request message for requesting start of data transfer is received from the terminal that has received the presence notification message via the relay device, the data stored in the storage area is not transmitted via the relay device. Transmitting to the terminal;
A data buffering method comprising: In the step of transmitting the data stored in the storage area to the terminal, the address information of the storage area in which the data is stored is added to the data and transmitted,
When the network address held by the terminal is updated, the updated network address and the address information of the storage area in which the data that has been received by the terminal are stored from the terminal via the relay device. Receiving step;
Based on the received address information, the terminal is not received, and the data stored in the storage area is transmitted to the terminal according to the updated network address;
After receiving the updated network address, transmitting data from the server to the terminal according to the updated network address;
The data buffering method according to claim 1, further comprising: Receiving data from the terminal to the server and header information for transmitting data from the terminal to the data buffering device;
Extracting data from the received data and header information, and transmitting the extracted data to the server;
The data buffering method according to claim 1, further comprising: Before receiving the data and the header information,
Receiving from the terminal a presence notification transmission request message for requesting notification of the presence of a data buffering device that performs data transmission to the server via the relay device;
As a response to the received presence notification transmission request message, sending a presence notification message for notifying the terminal of the presence of the device through the relay device;
The data buffering method according to claim 3, further comprising: A server and a plurality of terminals that mutually transmit and receive predetermined data;
A relay that is arranged between the server and the terminal, maintains a correspondence relationship between the network address of one or more own devices and the network address of each terminal, and relays data between the server and the terminal according to the correspondence relationship Equipment,
In a wireless network system having a communication method in which, when the server transmits data to the terminal, the network address of the relay device corresponding to the terminal is set as a transfer destination address.
Furthermore, the data buffering device is arranged between the server and the relay device, and realizes data transfer between the server and the terminal without going through the relay device,
Means for transmitting a presence notification message for notifying the terminal of the presence of the device that receives data from the server via the relay device when data is received from the server to the terminal;
When a buffering start request message for requesting start of data buffering is received from the terminal that has received the presence notification message via the relay device, the terminal from the server in the storage means provided in the own device Means for securing a storage area for buffering data to
Means for storing received data from the server to the terminal in the reserved storage area;
When a transfer start request message for requesting start of data transfer is received from the terminal that has received the presence notification message via the relay device, the data stored in the storage area is not transmitted via the relay device. Means for transmitting to the terminal;
A data buffering device comprising: The means for transmitting the data stored in the storage area to the terminal transmits the address information of the storage area in which the data is stored in addition to the data,
The data buffering device comprises:
When the network address held by the terminal is updated, the updated network address and the address information of the storage area in which the data that has been received by the terminal are stored from the terminal via the relay device. Means for receiving;
Means for transmitting, based on the received address information, data that has not been received by the terminal and stored in the storage area to the terminal according to the updated network address;
Means for transmitting the data from the server to the terminal according to the updated network address after receiving the updated network address;
The data buffering device according to claim 5, further comprising: The data buffering device comprises:
Means for receiving data from the terminal to the server and header information for transmitting data from the terminal to the data buffering device;
Means for extracting data from the received data and header information, and transmitting the extracted data to the server;
The data buffering device according to claim 5, further comprising: The data buffering device comprises:
Operates before receiving the data and the header information;
Means for receiving, from the terminal, a presence notification transmission request message for requesting notification of the presence of a data buffering device that performs data transmission to the server via the relay device;
As a response to the received presence notification transmission request message, means for transmitting a presence notification message for notifying the terminal of the presence of the device through the relay device;
The data buffering device according to claim 7, further comprising:   A data buffering program causing a computer to execute the data buffering method according to any one of claims 1 to 4.

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