JP2010166124A - Upper relay device, lower relay device, mobile terminal, communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lower relay device capable of achieving appropriate packet distribution, in a hierarchized communication system with migration transparency with a communication counterpart terminal maintained. <P>SOLUTION: The lower relay device includes: an address correspondence information storage part 21 where a plurality of pieces of mobile terminal identification information for identifying mobile terminals, and a plurality of pieces of address correspondence information for making local c/o addresses of the mobile terminals and area c/o addresses of the mobile terminals in a network for relaying packets to the mobile terminals correspond to each other are stored; a reception part 22 for receiving a packet using the area c/o address as a transmission destination; and a transmission part 25 for transmitting the packet by using, as a transmission destination, one of the local c/o address within the plurality of local c/o addresses corresponding to mobile terminal identification information made to correspond to the area c/o address by the address correspondence information when the reception part 22 receives the packet using the area c/o address as a transmission destination. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to, for example, a lower relay apparatus that can communicate with a mobile terminal using a plurality of routes in a lower relay apparatus corresponding to a mobility anchor point or the like.

  Conventionally, Mobile IPv6 has been proposed as a method for realizing mobility in the network layer (see, for example, Non-Patent Document 1). In this protocol, as a mobile terminal (sometimes called a “mobile node”) moves between networks (sometimes called a “handover”), the IP address assigned to the interface of the mobile terminal Even if there is a change, by making it possible to use the same IP address before and after the move, the mobility to the communication partner terminal (sometimes called "opposite node") is increased. Realized.

  Hierarchical mobile IPv6 has also been proposed (see Non-Patent Document 2, for example). In this protocol, in a handover within a domain, a local home agent existing in the domain (this home agent is referred to as “mobility anchor point”. Hereinafter, “mobility anchor point” may also be abbreviated as MAP. For example, registering the correspondence between the home address and the care-of address can reduce the handover delay.

  In addition, a protocol that allows a home agent to associate a plurality of care-of addresses with a single home address has been proposed (see, for example, Non-Patent Document 3). With this protocol, a mobile terminal in a multihoming environment (for example, a mobile terminal having a plurality of interfaces that can use a different IP address for each interface) maintains mobility to a communication partner terminal. However, it is possible to simultaneously transmit and receive packets via a plurality of paths.

  Also, in a terminal with multiple interfaces, considering the bandwidth and delay of each route and efficiently allocating packets to each route, the available bandwidth of each route is aggregated, rather than using a single route. A method for enabling communication with high throughput has also been proposed (see, for example, Non-Patent Document 4).

D. Johnson, C.I. Perkins, J.M. Arkko, “Mobility Support in IPv6”, RFC 3775, 2004 H. Soliman, C.I. Castelluccia, K.M. El Malki, L.M. Bellier, “Hierarchical Mobile IPv6 Mobility Management (HMIPv6)”, RFC 4140, 2005 R. Wakikawa, V.A. Devapalli, T .; Ernst, K.M. Nagami, “Multiple Care-of Address Registration”, Internet Draft, draft-ietf-monami6-multiplecoa-09. txt, 2008 K. Chebrolu, B.M. Raman, R.D. R. Rao, “A Network Layer Approach to Enable TCP over Multiple Interfaces”, Wireless networks, p. 637-650, 2005

  In hierarchical mobile IPv6, there has been a demand for efficiently transmitting packets to mobile terminals in a multihoming environment. However, even if the packet is distributed in the above-mentioned hierarchical mobile IPv6 MAP, the MAP can determine whether the packet received from the home agent is transmitted to the same destination. (This will be described in the embodiment), and there is a problem that appropriate packet distribution cannot be performed.

  Generally speaking, in a hierarchical communication environment in which a mobile terminal with multiple interfaces realizes movement transparency with a communication partner terminal, it is possible to appropriately manage communication paths and properly distribute packets. There was a problem that I could not go.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to address a local care-of address that is a care-of address of a mobile terminal in a network in which packets addressed to the mobile terminal having a plurality of interfaces are relayed. Is to appropriately manage the route to the mobile terminal.

  Another object is to perform appropriate distribution of packets in a higher-level relay device that relays packets whose destination is the home address of a mobile terminal having a plurality of interfaces.

  In order to achieve the above object, a lower-level relay apparatus according to the present invention includes mobile terminal identification information that is information for identifying a mobile terminal, a local care-of address that is a care-of address of the mobile terminal, and a packet addressed to the mobile terminal. An address correspondence information storage unit for storing a plurality of address correspondence information, which is information for associating a region care-of address as a care-of address of the mobile terminal in the relayed network, and reception for receiving a packet having the region care-of address as a transmission destination And a plurality of local care-of addresses corresponding to the mobile terminal identification information associated with the local care-of address by the address correspondence information when the receiver receives a packet whose destination is the local care-of address Among these, the packet received by the receiving unit is transmitted using any local care-of address as the transmission destination. It is obtained and a transmission unit.

  With such a configuration, it is possible to distinguish mobile terminals corresponding to local care-of addresses by using address correspondence information. Accordingly, when a plurality of local care-of addresses correspond to the same mobile terminal, transmission using any one of the local care-of addresses can be performed. For example, packet distribution or one communication can be performed. When a failure occurs in a route, another communication route can be used. In this way, the communication path with a mobile terminal having a plurality of interfaces can be managed in the lower level relay device.

  In addition, in the lower-level relay apparatus according to the present invention, when a plurality of packets whose destination is the area care-of address associated with the same mobile terminal identification information are received, the plurality of packets are identified as the mobile terminal identification. A distribution unit that distributes to a local care-of address corresponding to information; and when the reception unit receives a packet whose destination is a local care-of address, the packet is transmitted to the packet by the distribution unit. May be transmitted as a transmission destination.

  With such a configuration, it is possible to perform packet distribution in the lower-level relay device, and for example, it may be possible to achieve higher throughput than communication using a single communication path. Further, for example, when packet distribution is performed in both the upper relay apparatus and the lower relay apparatus, the load of packet distribution processing can be distributed to the upper relay apparatus and the lower relay apparatus. . Also, for example, when transmitting a probe packet for estimating communication quality when distributing packets, a method of transmitting a probe packet from a lower relay device rather than transmitting a probe packet from the higher relay device. Can perform quality estimation with less overhead. In addition, for example, compared to the case where the quality estimation of the communication path is performed by the higher-order relay device, the quality estimation can be performed at a position closer to the point where the communication route branches, because the quality estimation is performed by the lower-order relay device. Improvement in the accuracy of quality estimation can be expected.

  The lower-level relay apparatus according to the present invention further includes a distribution correspondence information storage unit that stores distribution correspondence information that is information for associating a local care-of address with a packet distribution ratio for each mobile terminal, and the distribution unit Is based on the distribution ratio corresponding to the distribution ratio corresponding to the mobile terminal identified by the mobile terminal identification information, with respect to a plurality of packets whose destinations are the area care-of addresses associated with the same mobile terminal identification information. May be assigned to the local care-of address associated with.

  With such a configuration, it is possible to distribute packets by using distribution correspondence information. Accordingly, appropriate packet distribution can be realized by appropriately setting the packet distribution ratio in the distribution correspondence information.

  The host relay device according to the present invention is information that associates a home address that is an unchanging address of a mobile terminal with a local care-of address that is a care-of address of the mobile terminal in a network in which packets addressed to the mobile terminal are relayed. When an upper address correspondence information storage unit storing a plurality of upper address correspondence information, a receiving unit receiving a packet whose home address is a destination, and a plurality of packets receiving the same home address as a destination And when the receiving unit receives a packet whose destination is the home address, and a distribution unit that distributes the plurality of packets to a plurality of area care-of addresses associated with the home address. The area care-of address to which the packet is distributed by the distribution unit is the destination. A transmission section for transmitting Te is obtained with a.

  With such a configuration, it is possible to distribute packets in the higher-level relay device, and for example, it may be possible to achieve higher throughput than communication using a single communication path.

  Further, in the higher order relay device according to the present invention, when the plurality of area care-of addresses corresponding to the same home address correspond to the same lower level relay device, the distribution unit includes a plurality of corresponding lower level relay devices. The distribution may be performed only for any one of the local care-of addresses.

  With such a configuration, when a packet is distributed in a lower relay device that receives a packet whose destination is the area care-of address transmitted from the upper relay device, unnecessary packets are not distributed in the upper relay device. It is possible to reduce the processing load of the higher-level relay device.

  The upper relay apparatus according to the present invention further includes, for each mobile terminal, an upper distribution correspondence information storage unit that stores upper distribution correspondence information that is information for associating an area care-of address with a packet distribution ratio. The unit may distribute a plurality of packets having the same home address as a transmission destination to the area care-of address associated with the distribution ratio according to the distribution ratio corresponding to the mobile terminal corresponding to the home address. Good.

  With such a configuration, it is possible to distribute packets by using the higher-level distribution correspondence information. Therefore, appropriate packet distribution can be realized by appropriately setting the packet distribution ratio in the high-order distribution correspondence information.

  The mobile terminal according to the present invention includes a mobile terminal identification information storage unit that stores mobile terminal identification information that is information for identifying the mobile terminal, a local care-of address that is a care-of address of the mobile terminal, and the mobile terminal An address generation unit that generates a local care-of address that is a care-of address of the mobile terminal in a network to which a packet addressed is relayed, mobile terminal identification information stored in the mobile terminal identification information storage unit, and the address generation Transmitting unit that receives the local care-of address generated by the unit and the local care-of address, a packet having the local care-of-address as the transmission destination, and transmits the packet to the lower level relay device that transmits the local care-of-address as the transmission destination And.

  With such a configuration, it is possible to transmit the mobile terminal identification information, the local care-of address, and the local care-of address to the lower-level relay device. By using such information, the lower-level relay apparatus can manage the communication path with a mobile terminal having a plurality of interfaces, and can perform packet distribution, for example. .

  The mobile terminal according to the present invention further includes a detection unit that detects that a lower level relay device to which a packet is relayed is changed, and when the detection unit detects that the lower level relay device has been changed, The generation unit may generate a local care-of address and a local care-of address, and the transmission unit may transmit the generated local care-of address and local care-of address and mobile terminal identification information.

  With such a configuration, mobile terminal identification information and the like can be transmitted to the lower relay apparatus at the timing when the lower relay apparatus is changed.

  According to the lower level relay apparatus and the like according to the present invention, it becomes possible to manage a route to a mobile terminal having a plurality of interfaces. Further, according to the higher-order relay apparatus and the like according to the present invention, when relaying a packet having a home address of a mobile terminal having a plurality of interfaces as a transmission destination, it is possible to appropriately distribute the packet.

The block diagram which shows the structure of the communication system by Embodiment 1 of this invention. The block diagram which shows the structure of the high-order relay apparatus by the embodiment The block diagram which shows the structure of the low-order relay apparatus by the embodiment The block diagram which shows the structure of the mobile terminal by the same embodiment Flowchart showing the operation of the upper relay device according to the embodiment The flowchart which shows operation | movement of the low-order relay apparatus by the embodiment The flowchart which shows operation | movement of the mobile terminal by the embodiment The figure for demonstrating each address in the embodiment The figure which shows an example of the packet distribution table in the embodiment The figure which shows an example of the address replacement table in the embodiment The figure which shows an example of the packet distribution table in the embodiment The figure which shows an example of the binding cache table in the embodiment The figure for demonstrating the movement of the mobile terminal in the embodiment The figure which shows an example of the packet distribution table in the embodiment The figure which shows an example of the binding cache table in the embodiment The figure for demonstrating the movement of the mobile terminal in the embodiment The figure which shows an example of the packet distribution table in the embodiment The figure which shows an example of the address replacement table in the embodiment The figure which shows an example of the packet distribution table in the embodiment The figure which shows an example of the binding cache table in the embodiment Schematic diagram showing an example of the appearance of the computer system in the embodiment The figure which shows an example of a structure of the computer system in the embodiment

  Hereinafter, a communication system according to the present invention will be described using embodiments. In the following embodiments, components and steps denoted by the same reference numerals are the same or equivalent, and repetitive description may be omitted.

(Embodiment 1)
A communication system according to Embodiment 1 of the present invention will be described with reference to the drawings. In the communication system according to the present embodiment, the upper relay device distributes packets, and the lower relay device also distributes packets to mobile terminals having a plurality of interfaces.

  FIG. 1 is a block diagram showing a configuration of a communication system according to the present embodiment. The communication system according to the present embodiment includes an upper relay device 1, two lower relay devices 2, 4, and a mobile terminal 3. These devices transmit and receive packets via wired or wireless communication lines 501 to 506 and routers 201 to 205. Note that the network configuration in FIG. 1 is merely an example, and the number and arrangement of devices, routers, and communication lines are not limited to this. The wired or wireless communication lines 501 to 506 are, for example, the Internet, an intranet, a public telephone line network, or the like.

  FIG. 2 is a block diagram showing a configuration of the upper relay apparatus 1 according to the present embodiment. In FIG. 2, the upper relay device 1 according to the present embodiment includes an upper address correspondence information storage unit 11, a reception unit 12, an upper distribution correspondence information storage unit 13, a distribution unit 14, a transmission unit 15, and an update unit. 16. In the present embodiment, the case where the upper relay apparatus 1 corresponds to a home agent in hierarchical mobile IPv6 will be mainly described.

  The upper address correspondence information storage unit 11 stores a plurality of upper address correspondence information. The upper address correspondence information includes a home address that is an unchanging address of the mobile terminal 3 and a local care-of address that is a care-of address of the mobile terminal 3 in a network to which a packet addressed to the mobile terminal 3 is relayed (RCoA in hierarchical mobile IPv6). Information). This upper address correspondence information is a so-called binding cache table in the hierarchical mobile IPv6 home agent.

  The invariable address of the mobile terminal 3 may be invariable as long as it is at least in a situation in which communication with mobility in the communication system is maintained, and may not be invariant throughout the future. It may be.

  “Associating the home address with the area care-of address” means that it is only necessary to acquire the other information from the information of one of the home address and the area care-of address. Therefore, the upper address correspondence information may include information including a home address and a local care-of address as a set, or may be information that links the home address and the local care-of address. In the latter case, the higher-order address correspondence information may be information that associates a home address and a pointer or address indicating the location where the area care-of address is stored, for example. In the present embodiment, the former case will be described. Further, the home address and the area care-of address may not be directly associated with each other. For example, the third information may correspond to the home address, and the area care-of address may correspond to the third information. Note that what is described in this paragraph is the same when two or more pieces of information are associated with each other.

  The process in which the upper address correspondence information is stored in the upper address correspondence information storage unit 11 does not matter. In the present embodiment, a case will be described in which upper address correspondence information is added or updated by the update unit 16 described later. The storage in the upper address correspondence information storage unit 11 may be a temporary storage in a RAM or the like, or may be a long-term storage. The upper address correspondence information storage unit 11 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.).

  The receiving unit 12 receives a packet whose destination is a home address. That is, the receiving unit 12 receives a packet whose destination is the home address included in the upper address correspondence information. Accordingly, when two or more home addresses are associated with the area care-of address in the upper address correspondence information storage unit 11, the reception unit 12 receives a packet having each home address as a transmission destination. Specifically, when the higher-order relay device 1 answers a neighbor search request related to the home address, the reception unit 12 can receive a packet whose destination is the home address. Note that the method for receiving a packet having the home address as a transmission destination is described in the above-mentioned Non-Patent Documents 1 and 2 and the like, and since it is already known, detailed description thereof is omitted.

  The receiving unit 12 may or may not include a wired or wireless receiving device (for example, a modem or a network card) for receiving. The receiving unit 12 may be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

  The upper distribution correspondence information storage unit 13 stores upper distribution correspondence information. The upper distribution correspondence information is information for associating the area care-of address with the packet distribution ratio for each mobile terminal. The packet distribution ratio is information indicating the ratio of how many packets are distributed. For example, when a certain mobile terminal has an area care-of address A and an area care-of address B, the higher-level sorting correspondence information associates the area care-of address A with the packet distribution ratio “40%” and Information that associates the address B with the packet distribution ratio “60%” may be used. In this case, 40% of the packets whose destination is the home address corresponding to the mobile terminal are transmitted with the area care-of address A as the transmission destination, and 60% are transmitted with the area care-of address B as the transmission destination. It will be. This ratio may be, for example, the ratio of the number of packets, the ratio of the data capacity of the packet, the ratio of the time when the packet is transmitted, or the other ratio. Good. Further, when two or more home addresses are stored in the upper address correspondence information storage unit 11, the correspondence between the area care-of address and the packet distribution ratio for the mobile terminal corresponding to each home address corresponds to the upper distribution. Assume that it is stored in the information.

  The process of storing the upper distribution correspondence information in the upper distribution correspondence information storage unit 13 does not matter. In the present embodiment, a case will be described in which higher-order sorting correspondence information is added or updated by the update unit 16 described later. The storage in the upper allocation correspondence information storage unit 13 may be a temporary storage in a RAM or the like, or may be a long-term storage. The upper allocation correspondence information storage unit 13 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.).

  The distribution unit 14 assigns a plurality of packets having the same home address as the transmission destination to the area care-of address associated with the distribution ratio according to the distribution ratio corresponding to the mobile terminal 3 corresponding to the home address. Distribute. Note that to distribute a packet to an address is to determine an address as a transmission destination of the packet. For example, for the mobile terminal 3 having a certain home address X, as described above, the area care-of address A and the packet distribution ratio “40%” correspond, and the area care-of address B and the packet distribution ratio “60%”. When the receiving unit 12 receives a packet whose destination is the home address X, the distribution unit 14 determines that 40% of the received packets have the area care-of address A. The received packet is distributed to each regional care address so that 60% is transmitted as the transmission destination and 60% is transmitted using the local care address B as the transmission destination.

  When the packet distribution ratio is, for example, the ratio of the number of packets, the distribution unit 14 manages the number of transmitted packets for each area care-of address in a counter or the like, and sets the counter or the like. Packets may be sorted while referring to them. More specifically, the distribution unit 14 may perform packet distribution using an algorithm such as cyclic round robin or centralized round robin. Further, when the packet distribution ratio is, for example, the ratio of the packet data capacity, the distribution unit 14 manages the total data capacity of the transmitted packets for each care-of address in a recording medium (not shown). In addition, packet distribution may be performed while referring to the total data capacity. In addition, when the packet distribution ratio is, for example, the ratio of time at which packets are transmitted, the distribution unit 14 manages the length of time to be transmitted for each local care-of address by using a timer or the like. In addition, time division may be performed while referring to the timer or the like. Note that such a packet distribution method is already known and will not be described in detail.

  When the receiving unit 12 receives a packet whose destination is the home address, the transmitting unit 15 transmits the packet using the area care-of address to which the packet is distributed by the distributing unit 14 as the transmission destination. The method of transmitting the area care-of address as the transmission destination is not limited as long as the area care-of address is the transmission destination. For example, in hierarchical mobile IPv6, a packet received by the receiving unit 12 is encapsulated, and the destination of the header of the encapsulated packet is the region care-of address. A packet whose destination is the area care-of address is received by any one of the lower-level relay devices. Note that the transmission processing by the transmission unit 15 is also described in the above-mentioned Non-Patent Documents 1 and 2 and the like, and since it is already known, detailed description is omitted.

  The transmission unit 15 may or may not include a transmission device (for example, a modem or a network card) for transmission (in this case, between the transmission unit 15 and the communication line 500). There is a transmitting device not shown in the figure). The transmission unit 15 may be realized by hardware, or may be realized by software such as a driver that drives the transmission device.

  The update unit 16 appropriately updates the upper address correspondence information stored in the upper address correspondence information storage unit 11 and the upper distribution correspondence information stored in the upper distribution correspondence information storage unit 13. For example, when a new set of home address and area care-of address transmitted from the mobile terminal 3 (which is a binding update in hierarchical mobile IPv6) is received, the update unit 16 responds accordingly. Update address correspondence information. Moreover, the update part 16 confirms the quality of a communication path, and updates a distribution ratio according to the quality. For example, when there are two communication paths related to a certain mobile terminal, if the quality of one communication path is significantly reduced, the distribution ratio is updated so that the distribution ratio of the other communication path is increased. Also good. The communication path quality is, for example, throughput, delay, jitter, and the like. For example, a delay can be measured using the PING round trip time. Note that these quality measuring methods are already known and will not be described. In the measurement, for example, a probe packet may be transmitted, or a packet transmitted and received between apparatuses without transmitting a probe packet may be used. Also, a method of updating the distribution ratio that lowers the distribution ratio of the poor quality route and increases the distribution ratio of the high quality route is already known, and the description thereof is omitted.

  The upper address correspondence information storage unit 11 and the upper distribution correspondence information storage unit 13 may be realized by the same recording medium or may be realized by separate recording media. In the former case, the area storing the high-order address correspondence information is the high-order address correspondence information storage unit 11, and the area storing the high-order distribution correspondence information is the high-order distribution correspondence information storage unit 13.

  As a result, as long as information corresponding to the higher-order address correspondence information and the higher-order distribution correspondence information is stored in the higher-order relay device 1, the way of holding the information is not limited. For example, upper address correspondence information and upper sorting correspondence information may be configured as integrated information.

  FIG. 3 is a block diagram showing a configuration of the lower relay apparatus 2 according to the present embodiment. In FIG. 3, the lower-level relay apparatus 2 according to the present embodiment includes an address correspondence information storage unit 21, a reception unit 22, a distribution correspondence information storage unit 23, a distribution unit 24, a transmission unit 25, and an update unit 26. Is provided. In the present embodiment, a case will be mainly described in which the lower level relay apparatus 2 corresponds to a mobility anchor point (MAP) in hierarchical mobile IPv6. Further, it is assumed that the lower relay apparatus 4 has the same configuration as the lower relay apparatus 2.

  The address correspondence information storage unit 21 stores a plurality of address correspondence information. The address correspondence information includes the mobile terminal identification information that is information for identifying the mobile terminal 3, the local care-of address that is the care-of address of the mobile terminal 3 (the LCoA in the hierarchical mobile IPv6), and the address for the mobile terminal 3. Information associated with the local care-of address of the mobile terminal 3 in the network where the packet is relayed. The correspondence between the local care-of address and the local care-of address in the address correspondence information is the same as the correspondence in the so-called binding cache table in the MAP of the hierarchical mobile IPv6.

  The mobile terminal identification information may be, for example, the home address of the mobile terminal 3 or other identification information. As other identification information, for example, there is a network access identifier (NAI: Network Access Identifier). Refer to RFC 4282 for the network access identifier. Also, refer to RFC 4283 for a method for assigning the network access identifier to the control packet. In the present embodiment, a case where the mobile terminal identification information is a home address will be described.

  The process of storing the address correspondence information in the address correspondence information storage unit 21 is not limited. In the present embodiment, a case will be described in which address correspondence information is added or updated by the update unit 26 described later. The storage in the address correspondence information storage unit 21 may be temporary storage in a RAM or the like, or may be long-term storage. The address correspondence information storage unit 21 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.).

  In the lower level relay apparatus 2 according to the present embodiment, by holding this address correspondence information, it is determined whether a packet having a plurality of regional care-of addresses as a transmission destination is a packet transmitted to the same mobile terminal. Will be able to. As will be described later, when transmitted to the same mobile terminal, packet distribution can be performed as appropriate. On the other hand, in the conventional hierarchical mobile IPv6, the MAP can know the correspondence between the local care-of address and the local care-of address by the binding update. It was not possible to determine whether the packet was sent to the terminal. Therefore, in the conventional hierarchical mobile IPv6, it is not possible to distribute packets in the MAP.

  The receiving unit 22 receives a packet whose destination is an area care-of address. That is, when two or more regional care-of addresses are associated with the mobile terminal identification information or the like in the address correspondence information storage unit 21, the reception unit 22 receives a packet whose destination is each local care-of address. become. It should be noted that the reception unit 22 can receive a packet having the area care-of address as the transmission destination by answering the neighbor search request related to the area care-of address, This is the same as in the case of the receiving unit 12. The method for receiving a packet whose destination is the care-of address is described in the above-mentioned Non-Patent Document 2 and the like, and since it is already known, detailed description thereof is omitted.

  The receiving unit 22 may or may not include a wired or wireless receiving device (for example, a modem or a network card) for receiving. The receiving unit 22 may be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

  The distribution correspondence information storage unit 23 stores distribution correspondence information. The distribution correspondence information is the same information as the higher-order distribution correspondence information except that the local care-of address becomes a local care-of address, and is information that associates the local care-of address with the packet distribution ratio for each mobile terminal 3. is there. The packet distribution ratio is the same as that described in the upper distribution correspondence information.

  The process in which the distribution correspondence information is stored in the distribution correspondence information storage unit 23 does not matter. In the present embodiment, a case will be described in which the distribution correspondence information is added or updated by the update unit 16 described later. The storage in the distribution correspondence information storage unit 23 may be temporary storage in a RAM or the like, or may be long-term storage. The distribution correspondence information storage unit 23 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, or the like).

  The distribution unit 24 selects a plurality of packets whose destinations are local care-of addresses associated with the same mobile terminal identification information according to a distribution ratio corresponding to the mobile terminal 3 identified by the mobile terminal identification information. , It distributes to the local care-of address associated with the distribution ratio. The distribution unit 24 acquires the mobile terminal identification information corresponding to the area care-of address that is the transmission destination of the packet received by the reception unit 22 by using the address correspondence information, thereby the mobile terminal 3 that is the transmission destination of the packet. Can be specified. The distribution unit 24 can distribute the packet by referring to the distribution correspondence information corresponding to the identified mobile terminal 3. Note that, by performing such distribution, processing different from the conventional determination of the transmission destination using the binding cache table may be performed. That is, in the binding cache table, when the area care-of address A and the local care-of address B are associated with each other, in the case of the conventional hierarchical mobile IPv6, a packet having the area care-of address A as a transmission destination is The local care-of address B corresponding to the local care-of address A has been transmitted as a transmission destination. By distributing the packet by the distribution unit 24, a packet having the local care-of address A as the transmission destination is transmitted. A local care-of address other than the local care-of address B corresponding to the local care-of address A may be transmitted as a transmission destination. The distribution method by the distribution unit 24 is the same as the distribution method by the distribution unit 14 except that the local care-of address is changed to the local care-of address, and the description thereof is omitted. In addition, about a specific distribution method, you may employ | adopt another in the distribution part 14 and the distribution part 24. FIG. For example, the distribution unit 14 may perform distribution according to the number of packets, and the distribution unit 24 may perform time division distribution.

  When the receiving unit 22 receives a packet having the area care-of address as the transmission destination, the transmission unit 25 transmits the packet using the local care-of address to which the packet is distributed by the distribution unit 24 as the transmission destination. The method of transmitting the local care-of address as the transmission destination is not limited as long as the local care-of-address is the transmission destination. For example, in hierarchical mobile IPv6, a packet received by the receiving unit 22 is encapsulated, and the destination of the header of the encapsulated packet is the local care-of address. A packet whose destination is the local address is received by the mobile terminal 3. Note that the transmission processing by the transmission unit 25 is also described in the above-mentioned Non-Patent Documents 1 and 2 and the like, and since it is already known, detailed description is omitted.

  The transmission unit 25 may or may not include a transmission device (for example, a modem or a network card) for performing transmission. The transmission unit 25 may be realized by hardware, or may be realized by software such as a driver that drives the transmission device.

  The update unit 26 appropriately updates the address correspondence information stored in the address correspondence information storage unit 21 and the distribution correspondence information stored in the distribution correspondence information storage unit 23. For example, a new set of mobile terminal identification information, a local care-of address, and a local care-of address transmitted from the mobile terminal 3 (the mobile terminal identification information added to the binding update in the hierarchical mobile IPv6) is received. If it has been done, the updating unit 26 updates the address correspondence information accordingly. Moreover, the update part 26 confirms the quality of a communication path, and updates a distribution ratio according to the quality. The updating method is the same as that described in the updating unit 16, and the description thereof is omitted.

  The address correspondence information storage unit 21 and the distribution correspondence information storage unit 23 may be realized by the same recording medium or may be realized by separate recording media. In the former case, the area storing the address correspondence information is the address correspondence information storage unit 21, and the area storing the distribution correspondence information is the distribution correspondence information storage unit 23.

  As a result, as long as the information corresponding to the address correspondence information and the distribution correspondence information is stored in the lower relay apparatus 2, the way of holding the information is not limited. For example, the address correspondence information and the distribution correspondence information may be configured as a single piece of information, or may be separated into two or more pieces of information in a manner different from that information.

  FIG. 4 is a block diagram showing a configuration of mobile terminal 3 according to the present embodiment. In FIG. 4, the mobile terminal 3 according to the present embodiment has a plurality of communication interfaces, and includes a mobile terminal identification information storage unit 31, a reception unit 32, a processing unit 33, a detection unit 34, and an address generation unit. 35 and a transmission unit 36. Note that the case where the mobile terminal 3 corresponds to a so-called mobile terminal (mobile node) in the hierarchical mobile IPv6 will be mainly described. The mobile terminal 3 may be, for example, a smartphone or PDA having a plurality of communication interfaces.

  The mobile terminal identification information storage unit 31 stores mobile terminal identification information that is information for identifying the mobile terminal 3. As described above, the mobile terminal identification information may be a home address corresponding to the mobile terminal 3, for example, or may be other identification information. In this embodiment, as described above, a case where the mobile terminal identification information is a home address will be described. Even if mobile terminal identification information that is not a home address is stored in the mobile terminal identification information storage unit 31, in the case of hierarchical mobile IPv6, the home address is stored in the mobile terminal identification information storage unit 31. May be. This is because a home address is required when sending a binding update to the higher-level relay device (home agent) 1.

  The process in which mobile terminal identification information is memorize | stored in the mobile terminal identification information storage part 31 is not ask | required. For example, the mobile terminal identification information may be stored in the mobile terminal identification information storage unit 31 via a recording medium, and the mobile terminal identification information transmitted via a communication line or the like is stored in the mobile terminal identification information storage unit Alternatively, the mobile terminal identification information input via the input device may be stored in the mobile terminal identification information storage unit 31. Storage in the mobile terminal identification information storage unit 31 may be temporary storage in a RAM or the like, or may be long-term storage. The mobile terminal identification information storage unit 31 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.).

  The receiving unit 32 receives a packet whose destination is the local address corresponding to the mobile terminal 3. Since the mobile terminal 3 according to the present embodiment has a plurality of communication interfaces, the reception unit 32 receives a packet for each of the plurality of communication interfaces. For example, the receiving unit 32 may include a wireless LAN communication interface and a communication interface for information communication using a mobile phone such as 2G or 3G. Note that a method in which the receiving unit 32 receives a packet whose destination is a local care-of address is already known as IPv6 technology, and a description thereof will be omitted.

  The receiving unit 32 may or may not include a wired or wireless receiving device (for example, a modem or a network card) for receiving. The receiving unit 32 may be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

  The processing unit 33 performs processing such as decapsulation on the packet received by the receiving unit 32, and appropriately performs processing of passing the packet to a corresponding component or the like. Note that the processing of the processing unit 33 is already known as IPv6 technology, and a description thereof will be omitted.

  The detection unit 34 detects that the lower level relay device to which the packet is relayed has changed. As the mobile terminal 3 moves, a situation occurs in which the lower level relay device to which the packet is relayed changes. For example, the detection unit 34 temporarily stores the address of the lower relay device included in the router advertisement transmitted by the access router in a recording medium (not shown), and stores the lower relay device stored in the recording medium. When the address and the address of the lower relay device included in the router advertisement are different, it may be detected that the lower relay device has changed. It goes without saying that other detection methods may be used. The address of the lower relay device included in the router advertisement is the address of the lower relay device in the domain to which the access router that transmitted the router advertisement belongs. In addition, the router advertisement including the address of the lower relay apparatus by the access router can be realized by using the MAP option of the hierarchical mobile IPv6. In addition, when it is detected that the lower relay device has been changed, address registration and the like are performed for the upper relay device 1 and the new lower relay device. This process will be described later. Further, when it is detected that the lower level relay device has been changed, the detection unit 34 updates the address of the lower level relay device temporarily stored in a recording medium (not shown) by overwriting. In addition, when the lower level relay device is changed, the access router is also changed, so that the network prefix of the subnet to which the mobile terminal 3 belongs is temporarily stored in a recording medium (not shown) as will be described later. Alternatively, the detection unit 34 may update the network prefix by overwriting it with a new one.

  Further, the detection unit 34 may detect that the access router that relays the packet has been changed. Strictly speaking, the detection unit 34 may detect that the access router has been changed, but the lower level relay apparatus has not been changed. As the mobile terminal 3 moves, a situation occurs in which the access router to which the packet is relayed changes in the domain of one lower relay apparatus. The detecting unit 34 temporarily illustrates, for example, the address of the lower relay device and the network prefix of the subnet included in the router advertisement transmitted by the access router (this subnet is the subnet to which the mobile terminal 3 belongs). If the network prefix stored in the recording medium is different from the network prefix included in the router advertisement, the lower relay device address stored in the recording medium is stored. And the address of the lower level relay device included in the router advertisement may be detected together. It goes without saying that other detection methods may be used. Further, when it is detected that the access router has been changed, the binding update is performed on the lower level relay apparatus. This process will be described later. When it is detected that the access router has been changed, the detection unit 34 overwrites and updates the network prefix of the subnet temporarily stored in a recording medium (not shown).

  The address generation unit 35 generates a local care-of address that is a care-of address of the mobile terminal 3. Further, the address generation unit 35 generates an area care-of address that is a care-of address of the mobile terminal 3 in a network in which a packet addressed to the mobile terminal 3 is relayed. For example, the address generator 35 may generate a local care-of address using a network prefix of a subnet included in the router advertisement, or generate a local care-of address using a DHCP server existing in the subnet. Also good. In the former case, for example, the address generation unit 35 generates an IPv6 address in which the network prefix included in the router advertisement is the upper 64 bits and the MAC address of the communication interface of the mobile terminal 3 is the lower 64 bits. May be. Note that a packet having the local care-of address as a transmission destination is received at the communication interface corresponding to the MAC address used in the generation of the local care-of address. At this time, processing such as converting a 48-bit MAC address into the EUI-64 format may be performed. Such an IPv6 address generation method is already known and will not be described in detail. In addition, the address generation unit 35 may generate the area care-of address using, for example, the address of the lower relay device included in the router advertisement. Specifically, the address generation unit 35 acquires the upper 64 bits of the address of the lower relay device (this becomes the network prefix of the network to which the lower relay device belongs) and sets the upper 64 bits of the local care-of address, and the mobile terminal The IPv6 area care-of address may be generated by setting the MAC address of the communication interface 3 to the lower 64 bits of the area care-of address. This local care-of address is transmitted to the lower level relay device together with the local care-of-address generated using the same MAC address.

  Further, when the detection unit 34 detects that the lower level relay device has been changed, the address generation unit 35 generates the local care-of address and the local care-of address of the mobile terminal 3 as described above. Also good. Further, the address generation unit 35 generates a local care-of address of the mobile terminal 3 when it is detected by the detection unit 34 that the access router has been changed (however, the lower level relay device is not changed). May be.

  Note that the method by which the address generator 35 generates an address is not limited to these. The address generator 35 may generate an address by other methods. In addition, the generation of the address may include reading an address stored in the recording medium. Further, the local care-of address and the local care-of address generated by the address generation unit 35 may be stored in a recording medium (not shown).

  The transmission unit 36 transmits the mobile terminal identification information stored in the mobile terminal identification information storage unit 31, the local care-of address and the local care-of address generated by the address generation unit 35 to the lower-level relay device. For example, the transmission unit 36 can transmit a packet to the lower relay apparatus by setting the address of the lower relay apparatus included in the router advertisement as the transmission destination. As described above, the subordinate relay apparatus receives a packet whose destination is the local care-of address and transmits the packet using the local care-of address as the transmission destination. When the detection unit 34 detects that the lower relay device has been changed, the transmission unit 36 identifies the local care-of address and local care-of address generated by the address generation unit 35 after the detection, and mobile terminal identification Information may be transmitted to the lower relay apparatus. As described above, the information transmitted by the transmission unit 36 to the lower-level relay device is obtained by adding mobile terminal identification information to the binding update in the conventional hierarchical mobile IPv6. The addition of mobile terminal identification information in the hierarchical mobile IPv6 protocol is, for example, a mobility option that is a mechanism of hierarchical mobile IPv6 for adding additional information to the binding update (see Non-Patent Document 1 described above). May be used. Further, when the detection unit 34 detects that the lower relay device has been changed, the transmission unit 36 and the home address of the mobile terminal 3 (for example, the mobile terminal identification information storage as described above) May be transmitted to the higher-level relay device 1. In this case, it is assumed that the transmission unit 36 knows the address of the upper relay device 1 in advance.

  In addition, the transmission unit 36 is stored in the mobile terminal identification information storage unit 31 when it is detected by the detection unit 34 that the access router has been changed (however, the lower level relay device has not been changed). The mobile terminal identification information and the local care-of address generated by the address generation unit 35 after the detection may be transmitted to the lower relay apparatus. This is the same as the binding update transmitted to the lower relay apparatus in the normal handover in the same domain of the lower relay apparatus (MAP) in the hierarchical mobile IPv6, and detailed description thereof is omitted.

  The transmission unit 36 may or may not include a transmission device (for example, a modem or a network card) for performing transmission. The transmission unit 36 may be realized by hardware, or may be realized by software such as a driver that drives the transmission device.

Next, the operation of the higher-level relay apparatus 1 according to this embodiment will be described using the flowchart of FIG. Here, the case of hierarchical mobile IPv6 will be described.
(Step S101) The receiving unit 12 determines whether or not a packet having a home address as a transmission destination has been received. If it is received, the process proceeds to step S102; otherwise, the process proceeds to step S104.

  (Step S <b> 102) The distribution unit 14 distributes the received packet to one of the local care-of addresses using the high-order distribution correspondence information stored in the high-order distribution correspondence information storage unit 13.

  (Step S103) The transmission unit 36 encapsulates the packet received by the reception unit 12, and transmits the distributed region care-of address as a transmission destination. Then, the process returns to step S101.

  (Step S <b> 104) The receiving unit 12 determines whether a packet whose destination is the address of the higher-level relay device 1 has been received. If received, the process proceeds to step S105, and if not, the process proceeds to step S107. In this flowchart, it is assumed that the packet received by the receiving unit 12 in step S104 includes a home address and an area care-of address. That is, in step S104, it is determined whether a binding update from the mobile terminal 3 has been received. In this embodiment, a case where a binding identifier (BID: Binding Identification number) is included in a packet including the home address and the area care-of address will be described. This binding identifier is information that can be freely set in the mobile terminal 3, and in this embodiment, a different binding identifier is set for each communication interface with which the mobile terminal 3 communicates. For details of the binding identifier, see Non-Patent Document 3 described above.

  (Step S <b> 105) The updating unit 16 updates the upper address correspondence information stored in the upper address correspondence information storage unit 11 using the home address and the area care-of address included in the packet received by the receiving unit 12. . In the present embodiment, the upper address correspondence information is updated using the home address and the region care address included in the packet received by the receiving unit 12 and also using the binding identifier included in the packet. explain. Therefore, in the upper address correspondence information, the home address, the area care-of address, and the binding identifier are associated with each other. Specifically, the update unit 16 determines whether or not the region care-of address associated with the home address and the binding identifier included in the packet received in step S104 can be specified by the higher address correspondence information. To do. If the area care-of address corresponding to the existing communication interface is changed when it can be specified, the updating unit 16 receives the specified area care-of address in step S104. Overwrite with the local care-of address included in the packet. On the other hand, if it cannot be specified, communication via a new communication interface has started, so the update unit 16 determines the home address and area included in the packet received in step S104. New upper address correspondence information that associates the care-of address with the binding identifier is added to the upper address correspondence information storage unit 11.

  (Step S106) The update unit 16 updates the higher-order sorting correspondence information. Specifically, when the area care-of address is updated in step S105, the update unit 16 overwrites the area care-before address before update in the higher-level sorting correspondence information with the area care-of address after update. On the other hand, when a new local care-of address starts to be used (that is, when communication via a new communication interface is started), the update unit 16 uses the home address included in the packet received in step S104. The region care-of address included in the packet received in step S104 is added to the higher-level sorting correspondence information corresponding to the mobile terminal 3 corresponding to. Further, according to the addition, the packet distribution ratio is appropriately adjusted. Then, the process returns to step S101.

  (Step S107) The update unit 16 determines whether to update the distribution ratio. And when updating, it progresses to step S108, and when that is not right, it returns to step S101. For example, the update unit 16 determines to update the distribution ratio at the timing when a predetermined event (for example, the higher-level distribution correspondence information may be updated or may be another event) occurs. Alternatively, it may be determined that the distribution ratio is updated periodically (for example, every 5 minutes, every 10 minutes, every 30 minutes, etc.).

(Step S108) As described above, the updating unit 16 confirms the quality of the communication path by, for example, transmitting a probe packet or using a packet transmitted and received by the higher-level relay device 1, and according to the quality. Update the distribution ratio. Then, the process returns to step S101.
The update of the upper address correspondence information and the upper distribution correspondence information in the flowchart of FIG. 5 may be configured as single information or as two or more pieces of information divided by another method. If so, it may be different as appropriate. Even in such a case, the address can be updated, the address can be added, etc., using a method substantially similar to the above description.

  Moreover, although the case where the upper address correspondence information is updated using the binding identifier in step S105 has been described, this need not be the case. For example, the upper address correspondence information may be updated by the following method. However, in the following description, the lower 64 bits of the care-of address are assumed to be the MAC address of the interface through which communication using the care-of address is performed. Specifically, the update unit 16 specifies the area care-of address associated with the home address included in the packet received in step S104 by the higher-order address correspondence information. Then, the update unit 16 determines whether or not the lower 64 bits of the area care-of address included in the packet received in step S104 matches the lower 64 bits of any of the specified area care-of addresses. If they match, the region care-of address relating to the communication interface identified by the MAC address corresponding to the lower 64 bits is changed, so the update unit 16 is included in the packet received in step S104. The area care-of address is overwritten with the area care-of address where the lower-order 64 bits match the area care-of address. On the other hand, if the lower 64 bits of the area care-of address included in the packet received in step S104 does not match the lower 64 bits of any of the specified area care-of addresses, communication via a new communication interface is performed. Therefore, the updating unit 16 additionally writes new upper address correspondence information that associates the home address and the area care-of address included in the packet received in step S104 to the upper address correspondence information storage unit 11. To do. Even in this case, the upper address correspondence information can be updated.

Next, the operation of the lower relay apparatus 2 according to the present embodiment will be described using the flowchart of FIG. Here, the case of hierarchical mobile IPv6 will be described. The operation of the lower relay apparatus 4 is the same as the operation of the lower relay apparatus 2.
(Step S <b> 201) The receiving unit 22 determines whether a packet whose destination is the area care-of address is received. If received, the process proceeds to step S202. If not, the process proceeds to step S204.

  (Step S202) The distribution unit 24 uses the distribution correspondence information stored in the distribution correspondence information storage unit 23 to distribute the received packet to one of the local care-of addresses.

  (Step S203) The transmission unit 25 encapsulates the packet received by the reception unit 22, and transmits the distributed local address as a transmission destination. Then, the process returns to step S201.

  (Step S204) The receiving unit 22 determines whether or not a packet whose destination is the address of the lower-level relay device 2 has been received. If received, the process proceeds to step S205, and if not, the process proceeds to step S207. In this flowchart, it is assumed that the packet received by the receiving unit 22 in step S204 includes mobile terminal identification information, a local care-of address, and a local care-of address. That is, in step S204, it is determined whether or not a binding update from the mobile terminal 3 (however, mobile terminal identification information is added by the mobility option) has been received.

  (Step S205) The update unit 26 is stored in the address correspondence information storage unit 21 using the mobile terminal identification information, the local care-of address, and the local care-of address included in the packet received by the reception unit 22. Update address correspondence information. Specifically, the updating unit 26 specifies a set of local care-of address and local care-of address associated with the mobile terminal identification information included in the packet received in step S204 by the address correspondence information. Then, the update unit 26 determines whether or not the area care-of address included in the packet received in step S204 matches any one of the specified group care-of addresses. If they match, the local care-of address corresponding to the local care-of address is changed. Therefore, the updating unit 26 specifies the local care-of address included in the packet received in step S204. Overwrite the local care-of address of the set. On the other hand, if the area care-of address included in the packet received in step S204 does not match any of the specified area care-of addresses, or an address including mobile terminal identification information included in the packet received in step S204 If the correspondence information does not exist, communication via a new communication interface has started, or the mobile terminal identified by the mobile terminal identification information has newly entered the domain of the lower level relay device 2 Therefore, the updating unit 26 adds address correspondence information that associates the mobile terminal identification information, the local care-of address, and the local care-of address included in the packet received in step S204 to the address correspondence information storage unit 21. . Similar to the above description regarding step S105, it is possible to perform the same processing as described above by determining whether the lower 64 bits of the address corresponding to the MAC address match or not.

  (Step S206) The update unit 26 updates the distribution correspondence information. Specifically, when the local care-of address is updated by overwriting in step S205, the update unit 26 similarly uses the local care-of address before update in the distribution correspondence information as the local care-of-update after update. Overwrite with address. On the other hand, when new address correspondence information is generated in step 205, the updating unit 26 assigns distribution correspondence information corresponding to the mobile terminal 3 identified by the mobile terminal identification information included in the packet received in step S204. On the other hand, the local care-of address included in the packet received in step S204 is added. Further, according to the addition, the packet distribution ratio is appropriately adjusted. Then, the process returns to step S201.

  (Step S207) The update unit 26 determines whether to update the distribution ratio. And when updating, it progresses to step S208, and when that is not right, it returns to step S201. For example, the update unit 26 determines to update the distribution ratio at a timing when a predetermined event (for example, the distribution correspondence information may be updated or may be another event). Alternatively, it may be determined that the distribution ratio is updated regularly (for example, every 5 minutes, every 10 minutes, every 30 minutes, etc.).

(Step S208) As described above, the updating unit 26 confirms the quality of the communication path by, for example, transmitting a probe packet or using a packet transmitted / received by the lower level relay apparatus 2, and according to the quality. Update the distribution ratio. Then, the process returns to step S201.
Note that the address correspondence information and the distribution correspondence information in the flowchart of FIG. 6 are updated as a single piece of information or as two or more pieces of information divided by another method. May be different as appropriate. Even in such a case, the address can be updated, the address can be added, etc., using a method substantially similar to the above description.

Next, the operation of the mobile terminal 3 according to the present embodiment will be described using the flowchart of FIG. Here, the case of hierarchical mobile IPv6 will be described.
(Step S301) The receiving unit 32 determines whether a packet has been received. Note that this packet is a packet whose destination is any one of the local addresses corresponding to the mobile terminal 3.

  (Step S302) The processing unit 33 performs processing for releasing the encapsulation of the packet received by the receiving unit 32, and performs processing for passing the packet to a corresponding component or the like as appropriate. Then, the process returns to step S301.

  (Step S303) The receiving unit 32 determines whether a router advertisement has been received. If it has been received, the process proceeds to step S304; otherwise, the process returns to step S301.

  (Step S304) The detection unit 34 determines whether the lower-level relay device has been changed using the address of the lower-level relay device included in the received router advertisement. Specifically, the detection unit 34 determines whether or not the address of the lower relay device matches the temporarily stored address, and determines that the lower relay device has not been changed if they match. The process proceeds to step S308, and if they do not match, it is detected that the lower level relay apparatus has been changed, and the process proceeds to step S305.

  (Step S305) As described above, the address generation unit 35 generates a local care-of address and a local care-of address using the address of the lower relay apparatus included in the router advertisement and the network prefix of the subnet.

  (Step S <b> 306) The transmission unit 36 transmits the area care-of address generated by the address generation unit 35 and the home address stored in the mobile terminal identification information storage unit 31 to the higher-level relay device 1. In the present embodiment, as described above, since the binding identifier is associated with the home address or the like in the upper address correspondence information, the transmission unit 36 performs communication using the area care-of address to be transmitted. It is assumed that a binding identifier for identifying an interface is also transmitted to the upper relay apparatus 1. That is, the area care-of address, the home address, and the binding identifier are transmitted to the upper relay apparatus 1. Here, when the binding identifier is also transmitted, it is preferable that the mobile terminal 3 holds information for specifying the binding identifier corresponding to the local care-of address. The information may be, for example, information that associates a region care-of address with a binding identifier, or includes identification information (for example, a MAC address) of a communication interface that performs communication using a region care-of address and a binding identifier. It may be information to be associated. In the former case, the information is updated every time the area care-of address is updated.

  (Step S307) The transmission unit 36 transmits the local care-of address generated by the address generation unit 35, the local care-of address, and the mobile terminal identification information stored in the mobile terminal identification information storage unit 31 to the lower-level relay device. To do. As the address of this lower level relay device, the address included in the router advertisement received in step S303 may be used. Then, the process returns to step S301.

  (Step S308) The detection unit 34 determines whether the visited network has been changed using the network prefix of the subnet included in the received router advertisement. Specifically, the detection unit 34 determines whether or not the network prefix matches the temporarily stored one. If they match, the detection unit 34 determines that the visited network has not been changed, and step S301. Returning to FIG. 5, if they do not match, it is detected that the visited network has been changed, that is, that the access router has been changed, and the process proceeds to step S309.

  (Step S309) The address generation unit 35 generates a local care-of address using the network prefix of the subnet included in the router advertisement as described above.

  (Step S <b> 310) The transmission unit 36 includes a local care-of address generated by the address generation unit 35, a local care-of address stored in a recording medium (not shown), and a mobile terminal stored in the mobile terminal identification information storage unit 31. The identification information is transmitted to the lower relay apparatus. As the address of this lower level relay device, the address included in the router advertisement received in step S303 may be used. Then, the process returns to step S301.

  Although not described in the flowchart of FIG. 7, the mobile terminal 3 may appropriately transmit a packet for communication with the communication partner terminal. In addition, when the mobile terminal 3 uses a new communication interface, the processing of steps S305 to S307 may be executed in the same manner as when it is detected that the lower relay device has been changed. . In the present embodiment, when a new communication interface is used, a new binding identifier that does not overlap with the binding identifier used by the mobile terminal 3 is assigned to the communication interface. Shall be granted.

In the flowcharts of FIGS. 6 and 7, when the visited network is changed in the domain of the same lower relay device 2, the mobile terminal 3 transmits the mobile terminal identification information to the lower relay device 2. However, the mobile terminal identification information may not be included in the binding update in this case. Even when the mobile terminal identification information is not included, the local care-of address can be updated in the lower level relay apparatus 2 in the same manner as in the conventional hierarchical mobile IPv6.
Also, in the flowcharts of FIGS. 5 to 7, the processing is ended by power-off or a processing end interrupt.

Next, the operation of the communication system according to the present embodiment will be described using a specific example.
In this specific example, it is assumed that the address corresponding to the mobile terminal 3 is as shown in FIG. That is, the home address of the mobile terminal 3 is “HoA101”. Further, the mobile terminal 3 has three regional care-of addresses “RCoA101”, “RCoA102”, and “RCoA103”, and packets whose destinations are the regional care-of addresses “RCoA101” and “RCoA102” are transmitted to the lower-level relay device 2. The received packet whose destination is the area care-of address “RCoA103” is received by the lower level relay apparatus 4. Also, the local care-of address “RCoA101” corresponds to the local care-of address “LCoA101”, the local care-of address “RCoA102” corresponds to the local care-of address “LCoA102”, and the local care-of address “ RCoA103 "corresponds to the local care-of address" LCoA103 ". It is assumed that information indicating these correspondences is stored in a recording medium (not shown) of the mobile terminal 3. Therefore, in the case of the conventional hierarchical mobile IPv6, communication is performed through the communication path indicated by any of the arrows shown in FIG. On the other hand, in the communication system according to the present embodiment, the lower relay apparatuses 2 and 4 perform packet distribution. For example, a packet transmitted to the lower relay apparatus 2 using the RCoA 101 as the transmission destination address transmits the LCoA 102 to the transmission destination. May be transmitted to the mobile terminal 3 as the address.

  Further, in this specific example, it is assumed that the upper relay apparatus 1 stores the packet distribution table in FIG. 9 in which upper address correspondence information and upper distribution correspondence information are integrated. In the packet distribution table of FIG. 9, the home address, traffic class, area care-of address, binding identifier, and distribution ratio are associated with each other. The traffic class is information included in the header of the packet. By this traffic class, communication that does not require real-time property such as FTP and communication that requires real-time property such as a video stream are distinguished. Is possible. If the traffic class included in the header of the received packet is “0”, the distribution unit 14 distributes the packet using a record whose traffic class is “0” in the table of FIG. If the traffic class included in the header of the packet is “1”, the packet is sorted using the record whose traffic class is “1” in the table of FIG. In FIG. 9, since the home address and the area care-of address are associated with each other, and the area care-of address and the distribution ratio are associated with each other, the packet distribution table in FIG. It can be said that the distribution correspondence information is included.

  As can be seen from the packet distribution table of FIG. 9, packets whose destination is the home address “HoA101” are not distributed to the regional care-of address “RCoA102” (the distribution ratio corresponding to the RCoA102). Is set to 0%). This is because it is not necessary to distribute packets because the destinations of the area care-of addresses “RCoA101” and “RCoA102” are both the same lower relay apparatus 2. That is, when a plurality of area care-of addresses correspond to the same subordinate relay apparatus (specifically, when a packet having a plurality of area care-of addresses as a transmission destination is received by the same subordinate relay apparatus) The packet distribution table (or higher-level distribution correspondence information) may be set so that packets are distributed only to any one of a plurality of local care-of addresses corresponding to the same lower relay apparatus. In this way, unnecessary packet distribution processing can be avoided, and the processing load on the higher-level relay device 1 can be reduced.

  Further, in this specific example, in the lower level relay apparatus 2, the address replacement information in FIG. 10, which is information corresponding to the address correspondence information and the distribution correspondence information, the packet distribution table in FIG. 11, and the binding cache table in FIG. And are stored. In the address replacement table of FIG. 10, mobile terminal identification information that is a home address is associated with an area care-of address. Further, in the packet distribution table of FIG. 11, mobile terminal identification information, traffic class, local care-of address, and distribution ratio are associated with each other. The traffic class is as described above. In the binding cache table of FIG. 12, the area care-of address and the local care-of address are associated with each other. This binding cache table is the same as the binding cache table used in the conventional hierarchical mobile IPv6 MAP. 10, 11, and 12, the mobile terminal identification information, the local care-of address, and the local care-of address are associated with each other through the mobile terminal identification information, and the local care-of address and the distribution ratio are Since the area care-of address and the local care-of address are associated with each other, the address replacement table in FIG. 10, the packet distribution table in FIG. 11, and the binding cache table in FIG. It can be said that it is equivalent to the address correspondence information and the distribution correspondence information as a whole.

  Next, specific processing will be described. Assume that a packet whose destination is the home address “HoA101” is transmitted from a communication partner terminal (not shown). Then, the packet is received by the receiving unit 12 of the higher-level relay device 1 (step S101). If the traffic class included in the header of the packet is “1”, the distribution unit 14 searches the packet distribution table using the home address “HoA101” and the traffic class “1” as search keys. In this case, the fourth to sixth records in FIG. 9 are hit. Then, the distribution unit 14 distributes the received packet to any one of the regional care-of addresses “RCoA101”, “RCoA102”, and “RCoA103” using the distribution ratio of these records (step S102). However, in this case, since the distribution ratio corresponding to the local care-of address “RCoA102” is 0%, the packet is not distributed to the local care-of address “RCoA102”. Here, it is assumed that the packet is distributed to the area care-of address “RCoA101”. Then, the transmission unit 15 encapsulates the packet received by the reception unit 12, and transmits the area care-of address “RCoA101” to which the packet is distributed as a transmission destination (step S103). At this time, the packet is configured such that the traffic class “1” included in the header of the packet received by the receiving unit 12 is also included in the header of the encapsulated packet.

  The packet transmitted from the upper relay device 1 in this way is received by the receiving unit 22 of the lower relay device 2. Then, the distribution unit 24 searches the address replacement table of FIG. 10 using the area care-of address “RCoA101” that is the transmission destination of the received packet as a search key, and reads the mobile terminal identification information “HoA101” from the hit record. Then, the distribution unit 24 searches the packet distribution table of FIG. 11 using the mobile terminal identification information and the traffic class “1” of the packet received by the reception unit 22 as a search key. In this case, the third and fourth records in FIG. 11 are hit. Then, the distribution unit 24 distributes the received packet to one of the local care-of addresses “LCoA101” and “LCoA102” using the distribution ratio of these records (step S202). Here, it is assumed that the packet is distributed to the local care-of address “LCoA102”. Then, the transmission unit 25 encapsulates the packet received by the reception unit 22, and transmits the local care-of address “LCoA102” to which the packet is distributed as a transmission destination (step S203).

  The packet transmitted from the lower-level relay apparatus 2 is received by the receiving unit 32 of the mobile terminal 3 (step S301), and the processing unit 33 performs processing such as decapsulation of the packet (step S302). ).

  Next, a process when the mobile terminal 3 moves from the subnet of the access router 204 to the subnet of the access router 210 as shown in FIG. When the mobile terminal 3 moves in such a manner, the receiving unit 32 of the mobile terminal 3 receives the router advertisement from the router 210 (step S303). Then, the detection unit 34 compares the address of the lower relay device included in the router advertisement with the address of the lower relay device temporarily stored in the mobile terminal 3. In this case, as shown in FIG. 13, since the lower level relay device is not changed, both addresses are matched, and the detection unit 34 determines that the lower level relay device is not changed (step S304). . Next, the detection unit 34 compares the subnet network prefix included in the router advertisement with the subnet network prefix temporarily stored in the mobile terminal 3. In this case, as shown in FIG. 13, since the subnet is moved, the subnet network prefix does not match, and the detection unit 34 determines that the visited network has been changed (step S308). Then, the detection unit 34 overwrites the temporarily stored network prefix of the subnet with the network prefix of the subnet included in the router advertisement. Further, the address generation unit 35 generates a local address using the network prefix of the new subnet and the MAC address of the communication interface used for communication with the access router 210 (step S309). The local care-of address is assumed to be “LCoA104”. Note that the information that associates the local care-of address with the local care-of address held in the mobile terminal 3 is updated as a new local care-of address is generated. That is, the local care-of address “LCoA102” is overwritten with the new local care-of address “LCoA104”.

  Thereafter, the transmission unit 36 transmits the mobile terminal identification information “HoA101” stored in the mobile terminal identification information storage unit 31, the new local care-of address “LCoA104”, and the region corresponding to the local care-of address “LCoA104”. A packet including the care-of address “RCoA102” is configured, and the packet is transmitted with the address of the lower relay apparatus included in the router advertisement as the transmission destination (step S310).

  The packet is received by the receiving unit 22 of the lower relay apparatus 2 (step S204). Then, the updating unit 26 searches the address replacement table of FIG. 10 using the mobile terminal identification information “HoA101” included in the received packet as a search key. In this case, the first and second records in FIG. 10 are hit. Then, the update unit 26 acquires the area care-of addresses “RCoA101” and “RCoA102” from the hit record, and searches the binding cache table of FIG. 12 using each as a search key. In this case, the first and second records in FIG. 12 are hit. The two hit records are a set of a local care-of address and a local care-of address corresponding to the mobile terminal identification information “HoA101” included in the packet received by the receiving unit 22. Thereafter, the updating unit 26 determines whether or not the region care-of address “RCoA102” included in the packet received by the receiving unit 22 is included in any of the first and second records in FIG. Since it is included in this case, the updating unit 26 determines that only the local care-of address has changed, and in the binding cache table of FIG. 10, the local care-of address “RCoA102” associated with the local care-of address “RCoA102”. The LCoA 102 "is overwritten with the local care-of address" LCoA 104 "included in the received packet. Further, the update unit 26 performs the same update for the packet distribution table of FIG. That is, the update unit 26 overwrites the local care-of address “LCoA102” of the second and fourth records in the packet distribution table of FIG. 11 with the local care-of address “LCoA104”. In this way, the address correspondence information, the distribution correspondence information, and the binding cache table are updated by the update unit 26 (steps S205 and S206). As a result, the packet distribution table is as shown in FIG. 14, and the binding cache table is as shown in FIG. Note that the distribution ratio may or may not be updated with the update of the local care-of address. Further, in this paragraph, the description has been made in accordance with the above description regarding step S205 in the flowchart of FIG. 6, but the update unit 26 may perform different processes as long as the processes are substantially the same. For example, the updating unit 26 determines whether or not the area care-of address associated with the mobile terminal identification information “HoA101” includes the area care-of address “RCoA102” in the address replacement table. The local care-of address associated with the regional care-of address “RCoA102” in the cache table may be updated, and the same update may be performed in the packet distribution table.

  Next, a process when the mobile terminal 3 moves from the domain of the lower relay apparatus 2 to the domain of the lower relay apparatus 5 as shown in FIG. It is assumed that the lower relay apparatus 5 has the same configuration as the lower relay apparatus 2 shown in FIG. When the mobile terminal 3 moves in such a manner, the receiving unit 32 of the mobile terminal 3 receives the router advertisement from the router 220 (step S303). Then, the detection unit 34 compares the address of the lower relay device included in the router advertisement with the address of the lower relay device temporarily stored in the mobile terminal 3. In this case, as shown in FIG. 16, since the lower level relay device has been changed, both addresses do not match, and the detection unit 34 determines that the lower level relay device has been changed (step S304). Then, the detection unit 34 overwrites the address of the lower relay apparatus temporarily stored with the address of the lower relay apparatus included in the router advertisement. In addition, the address generation unit 35 generates a local care-of address using the network prefix of the address of the lower relay apparatus 5 and the MAC address of the communication interface used for communication with the access router 220. The area care-of address is assumed to be “RCoA104”. In this case, since the subnet network prefix included in the router advertisement is also changed, the detection unit 34 uses the subnet network prefix temporarily stored as the subnet network prefix included in the router advertisement. Overwrite with. Further, the address generation unit 35 generates a local address using the network prefix of the new subnet and the MAC address of the communication interface used for communication with the access router 220 (step S305). The local care-of address is assumed to be “LCoA105”. Note that the information that associates the local care-of address with the local care-of address held in the mobile terminal 3 is updated as a new local care-of address is generated. That is, the local care-of address “LCoA102” is overwritten with the new local care-of address “LCoA105”, and the local care-of address “RCoA102” is overwritten with the new local care-of address “RCoA104”.

  Thereafter, the transmission unit 36 includes a packet including a home address “HoA101”, a new local care-of address “RCoA104”, and a binding identifier “2” that identifies a communication interface through which communication using the local care-of address “RCoA104” is performed. And the packet is transmitted to the upper relay apparatus 1 (step S306). As described above, by using the information for specifying the binding identifier corresponding to the area care-of address, which is held in the recording medium (not shown) of the mobile terminal 3, the transmission unit 36 uses the area care-of address “RCoA104. The binding identifier “2” corresponding to “” can be acquired.

  The packet is received by the receiving unit 12 of the higher-level relay device 1 (step S104). Then, the update unit 16 searches the packet distribution table of FIG. 9 using the home address “HoA101” and the binding identifier “2” included in the received packet as search keys. In this case, the second and fifth records in FIG. 9 are hit. Then, the update unit 16 overwrites the local care-of address “RCoA102” of each hit record with the local care-of address “RCoA104” included in the received packet. In this way, the upper address correspondence information and the upper allocation correspondence information are updated by the updating unit 16 (steps S105 and S106). As a result, the packet distribution table is as shown in FIG. Note that the distribution ratio may or may not be updated with the update of the area care-of address.

  In addition, the transmission unit 36 receives a packet including the mobile terminal identification information “HoA101” stored in the mobile terminal identification information storage unit 31, the new local care-of address “LCoA105”, and the new local care-of address “RCoA104”. Then, the packet is transmitted with the address of the lower relay apparatus 5 included in the router advertisement as the transmission destination (step S307).

  The packet is received by the receiving unit 22 of the lower level relay apparatus 5 (step S204). Then, the update unit 26 searches the address replacement table using the mobile terminal identification information “HoA101” included in the received packet as a search key. In this case, it is assumed that the mobile terminal identification information “HoA101” is not included in the address replacement table. Then, the update unit 26 determines that the mobile terminal 3 identified by the mobile terminal identification information “HoA101” has newly entered the domain of the lower relay apparatus 5, and receives the received mobile terminal identification information “HoA101”. A record including the region care-of address “RCoA104” is added to the address replacement table. In addition, the update unit 26 adds a record including the received mobile terminal identification information “HoA101” and the local care-of address “LCoA105” to the packet distribution table. In addition, the update unit 26 adds a record including the received local care-of address “RCoA104” and the local care-of address “LCoA105” to the binding cache table (steps S205 and S206). In addition, in the record addition to the packet distribution table, a record with a traffic class of 0 and a record of 1 are added. The distribution ratio included in the packet distribution table is set to 100% because there is no other path. As a result, the address replacement table stored in the lower relay apparatus 5 is as shown in FIG. 18, the packet distribution table is as shown in FIG. 19, and the binding cache table is as shown in FIG. Become. In FIGS. 18 to 20, only records relating to the mobile terminal 3 are displayed, but records relating to other mobile terminals may also exist.

  After that, the mobile terminal 3 transmits a request to the lower relay apparatus 2 to delete the record of the address replacement table, the packet distribution table, and the binding cache table related to the local care-of address in the subnet of the router 204. It is preferable. Even if the request is not transmitted, the associated records may be appropriately deleted in each lower-level relay apparatus when the binding expiration date or a communication error occurs.

  As shown in FIG. 9, when a plurality of area care-of addresses corresponding to the same lower relay apparatus are associated with one home address, the update unit 26 determines that the plurality of areas Of the care-of addresses, only the distribution ratio corresponding to one local care-of address may be set to be not 0, and the distribution ratios corresponding to other local care-of addresses may be set to zero. Here, a method for determining whether or not the area care-of address corresponds to the same subordinate relay apparatus will be described. When it is certain that the local care-of address included in the packet distribution table does not include the local care-of address, the upper 64 bits of the local care-of address are referred to, It may be determined that the same lower relay apparatus is supported. On the other hand, the local care-of address included in the packet distribution table may include a local care-of-address (that is, transmitted directly from the higher-level relay device 1 to the mobile terminal without going through the lower-level relay device). If there is also a communication path), the higher-level relay device 1 holds the address of each lower-level relay device or the network prefix. Then, referring to the upper 64 bits of the area care-of address included in the packet distribution table, they are the same, and the area care-of address that matches the network prefix of any of the lower-order relay devices held by them May correspond to the same lower relay apparatus. Needless to say, it may be determined whether or not the area care-of address corresponds to the same subordinate relay apparatus by other methods.

  As described above, according to the communication system according to the present embodiment, when a packet having a plurality of area care-of addresses as destinations is received by using address correspondence information in the lower level relay apparatuses 2 and 4, the packet It is possible to determine whether or not the transmission destinations are the same mobile terminal, and as a result, the lower level relay apparatuses 2 and 4 can distribute packets. Further, by distributing packets in both the upper relay device 1 and the lower relay devices 2 and 4, it becomes possible to distribute the load of the distribution processing. Further, the quality estimation of the communication path can be performed in the lower level relay apparatuses 2 and 4 so that the quality estimation with higher accuracy can be performed. In addition, when transmitting a probe packet in the quality estimation, overhead can be reduced as compared with a case where a probe packet is transmitted from the higher-level relay device 1.

  In the present embodiment, the description has been made mainly from the viewpoint of correcting the layered mobile IPv6 protocol. However, the communication system according to the present embodiment may be used in a protocol other than the layered mobile IPv6 protocol. Needless to say, it is good. That is, the protocol of the communication system according to the present embodiment is not limited. However, it is preferable that the communication interface identifier of the mobile terminal 3 is included in an address such as a local care address or a local care address used in this communication system, or that the communication interface identifier is transmitted together with the address. It is. This is because it is possible to determine whether the addresses correspond to the same communication interface.

  Further, in the present embodiment, as illustrated in FIG. 1, the case where the mobile terminal 3 communicates via the lower relay apparatuses 2 and 4 has been described, but this need not be the case. For example, the mobile terminal 3 may communicate directly with the upper relay device 1 without going through the lower relay device. In that case, the local care-of address becomes the local care-of address.

  Further, in the present embodiment, the upper allocation correspondence information and the distribution correspondence information are information for each mobile terminal, so the home address for identifying the corresponding mobile terminal, the mobile terminal identification information is the upper allocation correspondence information, It is preferable that it is included in the distribution correspondence information, but this need not be the case. For example, in the case of the upper allocation correspondence information, since the home address and the area care-of address are associated with each other in the upper address correspondence information, the mobile terminal corresponding to each area care-of address included in the upper distribution correspondence information is identified. Because it is possible. For example, in the case of distribution correspondence information, since the mobile terminal identification information and the local care-of address are associated with each other in the address correspondence information, the mobile terminal corresponding to each local care-of address included in the distribution correspondence information Because it can be identified.

  In the present embodiment, the case has been described in which the higher-level relay apparatus 1 performs packet distribution using the higher-level distribution correspondence information, but this need not be the case. That is, the distribution unit 14 may perform packet distribution without using the higher-order distribution correspondence information. In that case, when a plurality of packets having the same home address as the transmission destination are received, the distribution unit 14 appropriately distributes the plurality of packets to a plurality of local care-of addresses corresponding to the home address. It will be. The distribution method may be, for example, random distribution or other distribution. When the distribution unit 14 does not perform packet distribution using the upper distribution correspondence information, the upper relay device 1 may not include the upper distribution correspondence information storage unit 13.

  Further, even when a packet is distributed without using the higher-level distribution correspondence information, the distribution unit 14 is configured so that when a plurality of area care-of addresses corresponding to the same home address correspond to the same lower relay device, The distribution may be performed only for any one of a plurality of local care-of addresses corresponding to the same lower relay apparatus. For example, when the area care-of addresses A, B, and C corresponding to the same home address exist and the area care-of addresses A and B correspond to the same subordinate relay device, the distribution unit 14 Distribution to care-of addresses A and C may be performed, and distribution to local care-of addresses B and C may be performed. In this way, packet distribution may not be performed between a plurality of area care-of addresses corresponding to the same lower relay apparatus. A plurality of area care-of addresses corresponding to the same subordinate relay apparatus means that packets having the plurality of area care-of addresses as destinations are received by the same subordinate relay apparatus.

  In the present embodiment, the case has been described in which the lower relay apparatuses 2 and 4 perform packet distribution using the distribution correspondence information, but this need not be the case. That is, the distribution unit 24 may perform packet distribution without using the distribution correspondence information. In that case, when the distribution unit 24 receives a plurality of packets whose destination is the area care-of address associated with the same mobile terminal identification information, the distribution unit 24 identifies the plurality of packets as the mobile terminal identification. This is appropriately distributed to a plurality of local care-of addresses corresponding to the information. The distribution method may be, for example, random distribution or other distribution. When the distribution unit 24 does not distribute packets using the distribution correspondence information, the lower relay apparatuses 2 and 4 do not have to include the distribution correspondence information storage unit 23.

  Further, in the present embodiment, a case has been described in which the lower relay apparatuses 2 and 4 perform packet distribution, but this need not be the case. When the lower relay apparatuses 2 and 4 do not perform packet distribution, for example, when the receiving unit 22 receives a packet whose destination is the area care-of address, the area awareness is recognized by the address correspondence information. The packet may be transmitted by using any one of the local care-of addresses corresponding to the mobile terminal identification information associated with the address as a transmission destination. Therefore, for example, the following communication may be performed. In a normal case, when the receiving unit 22 receives a packet having the area care-of address as the transmission destination in the same manner as in the hierarchical mobile IPv6, the transmission unit 25 associates the area care-of address with the area care-of address. The packet is transmitted by using a local care-of address as a transmission destination. On the other hand, when a failure occurs in the communication path, the transmission unit 25 does not use the local care-of address via the communication path in which the failure occurs, The packet may be transmitted using the local care-of address. As described above, when the lower relay apparatuses 2 and 4 do not perform packet distribution, the lower relay apparatuses 2 and 4 may not include the distribution unit 24.

  Further, in the present embodiment, in the mobile terminal 3, the detection unit 34 detects that the lower relay device has been changed and transmits an address or the like to the lower relay device or the like, or has detected that the visited network has been changed. The case where the address or the like is transmitted to the lower relay apparatus has been described, but this need not be the case. For example, the address or the like may be transmitted to the lower relay apparatus or the upper relay apparatus 1 regardless of detection by the detection unit 34. More specifically, the address generation unit 35 generates a local care-of address and a local care-of address at that time periodically (for example, every minute, every five minutes, or every time a router advertisement is received). The transmitting unit 36 may transmit those addresses and the like to the lower relay device or the like. Then, for example, in the lower relay apparatus or the upper relay apparatus 1, it may be determined whether the local care-of address or the local care-of address is changed, and if it is changed, the address may be updated. In this case, the mobile terminal 3 does not have to include the detection unit 34.

  Further, in the present embodiment, a case has been described where packet distribution is performed in both the upper relay apparatus 1 and the lower relay apparatuses 2 and 4, but this need not be the case. For example, packet distribution may be performed only in the upper relay apparatus 1. In that case, the lower-level relay device is not described in the present embodiment. For example, the lower-level relay device has the same function as the MAP in the conventional hierarchical mobile IPv6, that is, transmits a certain area care-of address as a transmission destination. The received packet may be transmitted using the local care-of address corresponding to the local care-of address as a transmission destination. Further, for example, packet distribution may be performed only in the lower relay apparatuses 2 and 4. In that case, the higher-level relay device is not the nom described in the present embodiment, but has, for example, a device having the same function as the home agent in the conventional hierarchical mobile IPv6, that is, a certain home address as a transmission destination. May be transmitted with the area care-of address corresponding to the home address as the transmission destination.

  Further, in the present embodiment, the updating units 16 and 26 appropriately determine or update the packet distribution ratio by using a method similar to that described in Non-Patent Document 4 described above. May be. It goes without saying that the packet distribution ratio may be determined or updated by other methods. Further, the packet distribution ratio may be determined or updated by other than the update units 16 and 26. For example, the user may set manually.

  In the above embodiment, each process or each function may be realized by centralized processing by a single device or a single system, or may be distributedly processed by a plurality of devices or a plurality of systems. It may be realized by doing.

  In the above embodiment, information related to processing executed by each component, for example, information received, acquired, selected, generated, transmitted, or received by each component In addition, information such as threshold values, mathematical formulas, addresses, etc. used by each component in processing is retained temporarily or over a long period of time on a recording medium (not shown) even when not explicitly stated in the above description. It may be. Further, the storage of information in the recording medium (not shown) may be performed by each component or a storage unit (not shown). Further, reading of information from the recording medium (not shown) may be performed by each component or a reading unit (not shown).

  In the above embodiment, when information used by each component, for example, information such as a threshold value, an address, and various setting values used by each component may be changed by the user Even if it is not specified in the above description, the user may be able to change the information as appropriate, or it may not be. If the information can be changed by the user, the change is realized by, for example, a not-shown receiving unit that receives a change instruction from the user and a changing unit (not shown) that changes the information in accordance with the change instruction. May be. The change instruction received by the receiving unit (not shown) may be received from an input device, information received via a communication line, or information read from a predetermined recording medium, for example. .

  In the above embodiment, when two or more constituent elements included in each device constituting the communication system have a communication device, an input device, etc., the two or more constituent elements are physically within the scope of the object of the invention. May have a single device or separate devices.

  In the above embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. The software that realizes the lower relay apparatuses 2 and 4 in the above embodiment is the following program. That is, the program includes a receiving unit that receives a packet whose destination is an area care-of address that is a care-of address of the mobile terminal in a network in which the packet addressed to the mobile terminal is relayed, When receiving a packet whose destination is, the mobile terminal identification information that is information for identifying the mobile terminal, the local care-of address that is the care-of address of the mobile terminal, and the local care-of address of the mobile terminal are associated with each other Among a plurality of local care-of addresses corresponding to the mobile terminal identification information associated with the local care-of address by the address correspondence information stored in the address correspondence information storage unit in which a plurality of address correspondence information is stored , Any one of the local care-of addresses as the transmission destination Transmission unit signal for a program to function as a.

  Moreover, the software which implement | achieves the high-order relay apparatus 1 in the said embodiment is the following programs. In other words, this program is used when a computer receives a packet whose destination is a home address that is an invariant address of a mobile terminal, and a plurality of packets whose destination is the same home address. Information for associating the plurality of packets with the home address, the home address that is an unchanging address of the mobile terminal, and the local care-of address that is the care-of address of the mobile terminal in the network where the packet addressed to the mobile terminal is relayed A distribution unit that distributes to a plurality of regional care-of addresses associated with the high-order address correspondence information stored in the high-order address correspondence information storage unit that stores a plurality of high-order address correspondence information, and the reception unit transmits a home address When receiving a destination packet, the packet is The divided unit is a program for functioning as a transmitting unit, for transmitting the regional care-of address to which the packet is allocated as the destination.

  Moreover, the software which implement | achieves the mobile terminal 3 in the said embodiment is the following programs. That is, this program causes the computer to generate a local care-of address that is a care-of address of the mobile terminal and a local care-of address that is a care-of address of the mobile terminal in a network through which packets addressed to the mobile terminal are relayed. A mobile unit identification information stored in a mobile terminal identification information storage unit that stores mobile terminal identification information that is information for identifying the mobile terminal, a local care-of address generated by the address generation unit, and a region The care-of address is used to function as a transmission unit that receives a packet having a local care-of address as a transmission destination and transmits the packet to a lower level relay device that transmits the local care-of-address as a transmission destination.

  In the program, the functions realized by the program do not include functions that can be realized only by hardware. For example, functions that can be realized only by hardware such as a modem or an interface card in a receiving unit that receives information, a transmitting unit that transmits information, and the like are not included at least in the functions realized by the program.

Further, this program may be executed by being downloaded from a server or the like, and a program recorded on a predetermined recording medium (for example, an optical disc such as a CD-ROM, a magnetic disc, a semiconductor memory, etc.) is read out. May be executed. Further, this program may be used as a program constituting a program product.
Further, the computer that executes this program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

  FIG. 21 is a schematic diagram showing an example of the appearance of a computer that executes the program and realizes the upper relay device 1, the lower relay device 2, 4, and the mobile terminal 3 according to the embodiment. The above-described embodiment can be realized by computer hardware and a computer program executed on the computer hardware.

  21, a computer system 900 includes a computer 901 including a CD-ROM (Compact Disk Read Only Memory) drive 905 and an FD (Floppy (registered trademark) Disk) drive 906, a keyboard 902, a mouse 903, a monitor 904, and the like. Is provided.

  FIG. 22 is a diagram showing an internal configuration of the computer system 900. In FIG. 22, in addition to the CD-ROM drive 905 and the FD drive 906, a computer 901 is connected to an MPU (Micro Processing Unit) 911, a ROM 912 for storing a program such as a bootup program, and the MPU 911. A RAM (Random Access Memory) 913 that temporarily stores program instructions and provides a temporary storage space, a hard disk 914 that stores application programs, system programs, and data, and an MPU 911 and a ROM 912 are interconnected. And a bus 915. The computer 901 may include a network card (not shown) that provides connection to the LAN.

  A program that causes the computer system 900 to execute the functions of the upper relay device 1, the lower relay device 2, 4, and the mobile terminal 3 according to the above embodiment is stored in the CD-ROM 921 or the FD 922, and the CD-ROM drive 905, Alternatively, it may be inserted into the FD drive 906 and transferred to the hard disk 914. Instead, the program may be transmitted to the computer 901 via a network (not shown) and stored in the hard disk 914. The program is loaded into the RAM 913 when executed. The program may be loaded directly from the CD-ROM 921, the FD 922, or the network.

  The program does not necessarily include an operating system (OS) or a third-party program that causes the computer 901 to execute the functions of the upper relay device 1, the lower relay device 2, 4, and the mobile terminal 3 according to the above embodiment. Also good. The program may include only a part of an instruction that calls an appropriate function (module) in a controlled manner and obtains a desired result. How the computer system 900 operates is well known and will not be described in detail.

  Further, the present invention is not limited to the above-described embodiments, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the communication system and the like according to the present invention, for example, it is possible to perform packet distribution in the lower-level relay device, which is useful as a communication network or the like that maintains mobility to the communication partner terminal.

DESCRIPTION OF SYMBOLS 1 Upper relay apparatus 2, 4, 5 Lower relay apparatus 3 Mobile terminal 11 Upper address corresponding | compatible information storage part 12, 22, 32 Receiving part 13 Upper allocation corresponding | compatible information storage part 14, 24 Distributing part 15, 25, 36 Transmitting part 16, 26 update unit 21 address correspondence information storage unit 23 distribution correspondence information storage unit 31 mobile terminal identification information storage unit 33 processing unit 34 detection unit 35 address generation unit

Claims (12)

Mobile terminal identification information that is information for identifying the mobile terminal, local care-of address that is the care-of address of the mobile terminal, and regional care-of that is the care-of address of the mobile terminal in the network where packets addressed to the mobile terminal are relayed An address correspondence information storage unit for storing a plurality of address correspondence information, which is information for associating addresses,
A receiver that receives a packet whose destination is a local care-of address;
When the receiving unit receives a packet whose destination is an area care-of address, among a plurality of local care-of addresses corresponding to mobile terminal identification information associated with the area care-of address by the address correspondence information, A lower-level relay apparatus comprising: a transmission unit that transmits a packet received by the reception unit using any one of the local addresses as a transmission destination. When a plurality of packets whose destinations are local care-of addresses associated with the same mobile terminal identification information are received, the plurality of packets are distributed to local care-of addresses corresponding to the mobile terminal identification information. A distribution unit,
The transmitting unit, when the receiving unit receives a packet whose destination is an area care-of address, transmits the packet using the local care-of address to which the packet is distributed by the distributing unit as a transmission destination. Item 1. The lower level relay device according to Item 1. Each mobile terminal further includes a distribution correspondence information storage unit that stores distribution correspondence information, which is information associating the local care-of address with the packet distribution ratio,
The distribution unit, according to the distribution ratio corresponding to the mobile terminal identified by the mobile terminal identification information, a plurality of packets whose destination is the area care-of address associated with the same mobile terminal identification information, The lower level relay apparatus according to claim 2, wherein the lower level relay apparatus distributes the address to a local care-of address associated with the distribution ratio. A plurality of higher-level address correspondence information, which is information for associating the home address, which is an unchanging address of the mobile terminal, with the area care-of address, which is the care-of address of the mobile terminal in the network where the packet addressed to the mobile terminal is relayed, is stored. An upper address correspondence information storage unit;
A receiving unit that receives a packet whose destination is a home address;
When a plurality of packets having the same home address as a transmission destination are received, a distribution unit that distributes the plurality of packets to a plurality of area care-of addresses associated with the home address;
When the receiving unit receives a packet having a home address as a transmission destination, the upper relay includes: a transmission unit that transmits the packet using the area care-of address to which the packet is distributed by the distribution unit as a transmission destination apparatus. When the plurality of area care-of addresses corresponding to the same home address correspond to the same lower level relay apparatus, the distribution unit corresponds to any one of the plurality of area care-of addresses corresponding to the same lower level relay apparatus. The higher-order relay apparatus according to claim 4, wherein the higher-order relay apparatus performs the distribution only in the case of For each mobile terminal, the mobile phone further includes an upper distribution correspondence information storage unit that stores upper distribution correspondence information that is information for associating an area care-of address with a packet distribution ratio,
The distribution unit distributes a plurality of packets having the same home address as a transmission destination to an area care-of address associated with the distribution ratio according to a distribution ratio corresponding to the mobile terminal according to the home address. The upper relay apparatus according to claim 4. A mobile terminal identification information storage unit in which mobile terminal identification information, which is information for identifying the mobile terminal, is stored;
An address generation unit that generates a local care-of address that is a care-of address of the mobile terminal and a local care-of address that is a care-of address of the mobile terminal in a network in which a packet addressed to the mobile terminal is relayed;
The mobile terminal identification information stored in the mobile terminal identification information storage unit, the local care-of address and the local care-of address generated by the address generation unit are received, and a packet whose destination is the local care-of address is received, A mobile terminal comprising: a transmission unit that transmits a packet to a lower relay device that transmits a local address as a transmission destination. It further includes a detection unit that detects that the lower level relay device to which the packet is relayed has changed,
When it is detected by the detection unit that a lower relay device has been changed, the address generation unit generates a local care-of address and a local care-of address, and the transmission unit generates the generated local care-of address and The mobile terminal according to claim 7, wherein the local care-of address and the mobile terminal identification information are transmitted. Mobile terminal identification information that is information for identifying the mobile terminal, local care-of address that is the care-of address of the mobile terminal, and regional care-of that is the care-of address of the mobile terminal in the network where packets addressed to the mobile terminal are relayed A communication method that is processed using an address correspondence information storage unit that stores a plurality of address correspondence information that is information for associating addresses, a reception unit, and a transmission unit,
A receiving step in which the receiving unit receives a packet whose destination is a local care-of address;
When the transmission unit receives a packet whose destination is a local care-of address in the receiving step, a plurality of localities corresponding to mobile terminal identification information associated with the local care-of address by the address correspondence information A transmission method comprising: a transmission step of transmitting a packet received in the reception step with any one of the local care-of addresses as a transmission destination. A plurality of higher-level address correspondence information, which is information for associating the home address, which is an unchanging address of the mobile terminal, with the area care-of address, which is the care-of address of the mobile terminal in the network where the packet addressed to the mobile terminal is relayed, is stored. A communication method processed using an upper address correspondence information storage unit, a reception unit, a distribution unit, and a transmission unit,
A receiving step in which the receiving unit receives a packet whose destination is a home address;
When the distribution unit receives a plurality of packets having the same home address as a transmission destination, the distribution unit distributes the plurality of packets to a plurality of regional care-of addresses associated with the home address;
When the transmission unit receives a packet having a home address as a transmission destination in the reception step, the transmission step transmits the packet as a transmission destination, the area care-of address to which the packet is distributed in the distribution step; A communication method comprising: A communication method that is processed using a mobile terminal identification information storage unit that stores mobile terminal identification information that is information for identifying a mobile terminal, an address generation unit, and a transmission unit,
Address generation step in which the address generation unit generates a local care-of address that is a care-of address of the mobile terminal and a local care-of address that is a care-of address of the mobile terminal in a network in which a packet addressed to the mobile terminal is relayed When,
A packet in which the transmitting unit uses the mobile terminal identification information stored in the mobile terminal identification information storage unit, the local care-of address and the local care-of address generated in the address generation step as the transmission destination of the local care-of address. And a transmission step of transmitting the packet to a lower-level relay apparatus that transmits the packet using the local address as a transmission destination. Computer
An address generation unit that generates a local care-of address that is a care-of address of the mobile terminal and a local care-of address that is a care-of address of the mobile terminal in a network in which a packet addressed to the mobile terminal is relayed;
Mobile terminal identification information stored in a mobile terminal identification information storage unit that stores mobile terminal identification information that is information for identifying the mobile terminal, a local care-of address and a local care-of address generated by the address generation unit, For receiving a packet having a local care-of address as a transmission destination, and transmitting the packet to a lower-level relay apparatus that transmits the local care-of-address as a transmission destination.

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