JP4799584B2 - Network system and communication device - Google Patents

Description

  The present invention relates to a network system in which a server device assigns an IP (Internet Protocol) address in accordance with a request from a client device. The present invention also relates to a communication apparatus that can be applied to each of a server apparatus, a client apparatus, the client apparatus, and a relay apparatus that relays between the server apparatuses in such a network system.

  When communication is performed between communication devices such as personal computers connected to an IP network, it is necessary to assign an IP address to each communication device. As an IP address assignment method, a fixed (static) assignment method for each communication device and a dynamic assignment method according to, for example, Dynamic Host Configuration Protocol (hereinafter referred to as DHCP) (see, for example, Patent Document 1) Is known.

  In the method of assigning a fixed IP address, each time a communication device connected to the IP network is added or removed, the network administrator needs to assign and release an IP address to each communication device. Therefore, the network administrator needs to manage and grasp the IP address assignment status, and it is difficult to reduce the management burden. In addition, every time a user who uses an IP network adds or removes a communication device, the user needs to request the network administrator to assign or release an IP address, thereby reducing the effort of managing the IP address. It was difficult.

  In recent years, for example, in a local area network (hereinafter referred to as LAN) in a company, an IP address assignment method according to DHCP has become mainstream for the purpose of reducing the management cost of the IP address. Also, in the Internet environment, in order to improve the convenience of users who use the Internet, many Internet service provider operators (hereinafter referred to as ISP operators) use IP address assignment methods according to DHCP. It is being adopted.

When assigning an IP address to each communication device, each communication device notifies the server device that performs the IP address assignment processing of the Media Access Control address (hereinafter referred to as a MAC address) assigned to itself to the IP address. Request an assignment. The server device assigns an IP address for each MAC address of each communication device, and notifies the assigned IP address to each communication device. In this way, by assigning an IP address for each MAC address, even when an IP address is dynamically assigned, it is possible to prevent duplicate assignment of different IP addresses to the same communication device.
JP 2006-115033 A

  By the way, in recent years, a mobile communication network is shared by a virtual mobile network operator (MVNO), a fixed mobile convergence (FMC), etc., and the connection form to the mobile communication network, the mobile communication network Services through the Internet are diversifying. Network media (communication means) for connecting to mobile communication networks are also diversified.

  Furthermore, with the diversification of connection modes to IP networks, communication devices including a plurality of types of network media are provided so that one communication device can connect to different networks. In such a communication device, a MAC address is assigned to each network medium. Therefore, when an IP address is dynamically assigned to such a communication device according to DHCP, an IP address is assigned to each network medium (each MAC address).

  Therefore, there may be a situation in which a plurality of IP addresses are assigned to one user who uses one communication device. Therefore, the ISP company needs to secure more IP addresses than the number of subscribers of the service that it provides, and there is a problem that the address space may be exhausted. Or, it is necessary to register MAC addresses as many as the number of network media, and there is a problem that the network administrator work increases.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a network system capable of avoiding a situation in which a plurality of IP addresses are assigned to one user. It is in. It is another object of the present invention to provide a communication device that can be operated as a server device, a client device, and a relay device that can be applied to such a network system.

A network system disclosed in the present application is a network system in which a server device assigns an IP address in accordance with a request from a client device connected via a network. In the network system, a client device identifies user of its own device. And a request signal for requesting an IP address assignment to the server device via the network. The network system disclosed in the present application assigns an IP address and a home agent to each user identification information included in the received request signal when the server device receives the request signal, and assigns the assigned IP address and home agent. Is transmitted to the client apparatus that has transmitted the request signal. When a plurality of home agents are provided to transfer information transmitted to the IP address of each client device to a care-of address that is the destination address of each client device, and the server device receives a request signal Any home agent is assigned based on the load information in each home agent.

  According to the network system disclosed in the present application, the server device assigns an IP address for each user identification information of the user of the client device. In other words, an IP address is assigned to each user of a client device that is configured so that one device can connect to different networks. Therefore, it is possible to avoid a situation in which a plurality of IP addresses are assigned to the same user, as in the case where IP addresses are assigned to each network medium (each MAC address) provided in the client device.

In the network system disclosed in the present application, since an IP address is assigned to each user of a client device, a situation in which a plurality of IP addresses are assigned to the same user who uses one client device does not occur. Therefore, an ISP operator that assigns and manages IP addresses only needs to secure IP addresses as many as the number of subscribers of the service provided by the ISP operator, and there is no possibility that the reserved address space is exhausted. Therefore, it is possible to reduce network management costs. Further, since the utilization rate of each home agent is taken into consideration when assigning home agents, the load on each home agent can be distributed.

  Hereinafter, a network system according to the present invention will be described in detail with reference to the drawings showing embodiments thereof. First, the configuration of the network system according to the present embodiment will be described. FIG. 1 is a schematic diagram showing the configuration of a network system. The network system of the present embodiment is a mobile IP system, for example, a system configured according to mobile IPv6. The network system according to the present invention is not limited to the mobile IPv6 system, and can be applied to other systems such as a mobile IPv4 system.

  The network system of this embodiment includes DHCP servers 1, 1, home agents (hereinafter referred to as HA) 2, 2..., DHCP relay agent 3, DHCP client 4, and the like. The DHCP servers 1 and 1 are server devices that are components of the network system according to the present invention. The DHCP relay agent 3 is a relay device that is a component of the network system according to the present invention. The DHCP client 4 is a client device that is a component of the network system according to the present invention. HA2, 2,... Are general home agents for configuring a mobile IP system.

  The network system according to this embodiment is configured such that the DHCP server 1 assigns an IP address (home address) according to DHCP based on a request from the DHCP client 4. Regarding the DHCP servers 1 and 1 and the DHCP relay agent 3, DHCPv4 is defined in Request For Comments (hereinafter referred to as RFC) 2131, and DHCPv6 is defined in RFC3315.

  The DHCP servers 1, 1 and HA2, 2,... Are managed by their ISP providers and are connected to each other via a home network (home link) N2. FIG. 1 shows only the DHCP servers 1, 1 and HA2, 2,... Managed by two ISP providers (first ISP, second ISP). The number of ISP operators, the number of DHCP servers 1 managed by each ISP operator, the number of HA2, 2 and the like are not limited to the numbers shown in FIG. For simplification of description, it is assumed below that one ISP provider manages one DHCP server 1.

  The DHCP relay agent 3 is managed by a network access provider operator (NAP operator) such as a communication carrier. The DHCP servers 1 and 1 and the DHCP relay agent 3 are connected to each other via an IP network N1 such as the Internet, and the DHCP relay agent 3 is shared by the DHCP servers 1 and 1.

  The DHCP client 4 is a terminal device used by a user who uses the IP network N1, and is configured to be portable. Specifically, the DHCP client 4 is a mobile computer such as a notebook computer and a personal digital assistant (PDA), a mobile phone, and a mobile terminal device such as a personal handy-phone system (PHS).

  The DHCP relay agent 3 and the DHCP client 4 are connected via, for example, a wired LANN3 conforming to the Ethernet (registered trademark) standard and a wireless LANN4 conforming to, for example, the IEEE (Institute of Electrical and Electronic Engineers) 802.11b standard. Yes. In FIG. 1, one DHCP relay agent 3 and one DHCP client 4 are shown, but the number is not limited to these, and a plurality of each may be provided.

  In the network system having the above-described configuration, when the DHCP client 4 transmits a request signal (request message) for requesting IP address assignment, the DHCP relay agent 3 transfers the request signal to an appropriate DHCP server 1. When receiving the request signal, the DHCP server 1 selects one HA 2 from HA 2, 2... According to DHCP and assigns a home address or the like for the DHCP client 4 to connect to the home network N 2 (payout) ). Then, the DHCP server 1 notifies the DHCP client 4 of the assigned HA 2 IP address and home address via the DHCP relay agent 3. Accordingly, the DHCP server 1 can assign the home address (IP address) and the IP address of the HA 2 in accordance with a request from the DHCP client 4.

Next, the configuration of each of the DHCP server 1, HA2, DHCP relay agent 3, and DHCP client 4, which are components of the network system of the present embodiment, will be described. FIG. 2 is a block diagram showing the configuration of the DHCP server 1.
The DHCP server 1 includes a control unit 10, a read only memory (hereinafter referred to as ROM) 11, a random access memory (hereinafter referred to as RAM) 12, a hard disk drive (hereinafter referred to as HDD) 13, a first communication unit 14, and a second communication unit. A communication unit 15 and the like are provided, and these hardware units are connected to each other via a bus 1a. The DHCP server 1 can also be configured to include one communication unit and be connectable to the IP network N1 and the home network N2 via one communication unit. When configured in this way, the DHCP server 1 is bus-connected to the home network N2.

  The control unit 10 is, for example, a Central Processing Unit (hereinafter referred to as “CPU”) or a Micro Processor Unit (hereinafter referred to as “MPU”), and appropriately reads a control program stored in advance in the ROM 11 or the HDD 13 into the RAM 12 and executes it. The control unit 10 controls the operation of each hardware unit described above.

  The ROM 11 stores in advance various control programs necessary for operating the DHCP server 1 as a server device (communication device) in the network system according to the present invention. The RAM 12 is, for example, a static RAM (hereinafter referred to as SRAM) or a flash memory, and temporarily stores various data generated when the control unit 10 executes a control program.

  The HDD 13 is a large capacity storage device. The HDD 13 has various control programs necessary for operating the DHCP server 1 as a server device in the network system according to the present invention, a NAI (Network Access Identifier) information table 13a as shown in FIG. The user information table 13b as shown in FIG. 4B, the home address pool 13c as shown in FIG. 4A, the HA information pool 13d as shown in FIG.

The first communication unit 14 is an interface for connecting to the IP network N1, and communicates with devices connected to other networks via the IP network N1, such as the DHCP relay agent 3 connected to the IP network N1. To do.
The second communication unit 15 is an interface for connecting to the home network N2, and communicates with devices connected to other networks via the home network N2, such as HA2, 2,... Connected to the home network N2. To do.

  FIG. 3 is a schematic diagram showing registration contents of the NAI information table 13a and the user information table 13b. FIG. 4 is a schematic diagram showing registration contents of the home address pool 13c and the HA information pool 13d.

  In the NAI information table 13a, as shown in FIG. 3A, a plurality of NAI information is registered in association with an NAI information ID (IDentifier) for identifying NAI information. The NAI information is user identification information for identifying a user who subscribes to a service provided by an ISP that manages the DHCP server 1, and is given to each user when each user performs a service subscription procedure. Information.

  NAI information is defined in RFC4282. Specifically, the NAI information includes, for example, a user name given for each user (user1, user2, user3 in FIG. 3A) and a domain name (realm) for identifying the DHCP server 1 (see FIG. 3 (a) includes isp1.domain.name). Here, since one ISP provider manages one DHCP server 1, there is also one domain name for each ISP provider.

  The registered contents of the NAI information table 13a are such that, when NAI information is given to the user who has performed the service subscription procedure, the administrator inputs the NAI information via the operation unit (not shown) of the DHCP server 1, for example. Registered by the control unit 10 each time. The registered contents of the NAI information table 13a are stored in the NAI information table 13a by the control unit 10 every time the administrator instructs the deletion of the NAI information through the operation unit of the DHCP server 1, for example, when the service subscriber performs the withdrawal procedure. Deleted.

  In the user information table 13b, as shown in FIG. 3B, in correspondence with the NAI information ID, pool area information of the home address pool 13c, home address, pool area information of the HA information pool 13d, and IP address of HA2 User information including, for example, is registered. The pool area information of the home address pool 13c is information indicating in which pool area in the home address pool 13c the home address assigned to the user indicated by the NAI information ID is the pooled (accumulated) address. .

  The home address is a home address assigned (paid out) to the user indicated by the NAI information ID. The pool area information of the HA information pool 13d is information indicating which pool area in the HA information pool 13d is HA2 assigned to the user indicated by the NAI information ID. The IP address of HA2 is the IP address of HA2 assigned (assigned) to the user indicated by the NAI information ID.

  FIG. 3B shows an example in which the home address 11, home address 12, and home address 21 are registered in the home address column, but actually, for example, “3ffe: 1: 100 :: An IP address such as “100” is registered. Similarly, an example in which HA11, HA11, and HA21 are registered in the IP address column of HA2 is shown, but in practice, for example, “3ffe: 1: 100 :: 10” is assigned to HA2. The assigned IP address is registered. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.100” is registered in the home address column, and an IP address column of HA2 is, for example, An IP address such as “192.168.100.10” is registered.

  The registration contents of the user information table 13b are registered by the control unit 10 every time the DHCP server 1 assigns (pauses) a home address and any HA 2 to the DHCP client 4 in accordance with a request from the DHCP client 4. The

  In addition to the home address and the IP address of the HA 2, the DHCP server 1 responds to a request from the DHCP client 4, for example, a Session Initiation Protocol (SIP) server, a Domain Name System (DNS) server, a Network Time Protocol ( It is also assumed that each server device such as an (NTP) server is assigned. In this case, the IP addresses of the SIP server, DNS server, and NTP server assigned to the DHCP client 4 are also registered in the user information table 13b.

  The home address pool 13c has a plurality of pool areas. As shown in FIG. 4A, a plurality of home addresses are associated with pool area information for identifying the pool area. Registered (pooled) in advance. FIG. 4A shows an example in which home addresses 11, home addresses 12... Are registered in each pool area, but in practice, for example, “3ff: 1: 100 :: 100”. IP address is registered. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.100” is registered as the home address.

  The registered contents of the home address pool 13c are registered in advance, and each time the DHCP server 1 assigns a home address to the DHCP client 4, it is deleted by the control unit 10. Furthermore, the registered contents of the home address pool 13c are added to the corresponding pool area by the control unit 10 every time the home address assigned to the DHCP client 4 is released. Thereby, in the process of assigning the home address to each DHCP client 4 based on the registered contents of the home address pool 13c, it is possible to avoid the duplicate assignment of the same home address.

  The HA information pool 13d has a plurality of pool areas. As shown in FIG. 4B, the HA information pool 13d is associated with pool area information for identifying the pool area, and each pool area has an IP address of HA2. HA information including status information, usage rate (load information), etc. is registered (pooled). FIG. 4B shows an example in which HA11, HA12... Are registered in the IP address column of HA2 in each pool area, but actually, for example, assigned to HA2, 2,. An IP address such as “3ff: 1: 100 :: 10” is registered. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.10” is registered as the IP address of HA2.

  In the status information column of each pool area of the HA information pool 13d, whether each HA2, 2,... Is activated or stopped is registered. In the utilization rate column, the ratio of the number of DHCP clients 4 to which each HA2, 2,... Is actually allocated to the number of DHCP clients 4 that can share each HA2, 2,.

  The registered contents in the pool area information column of the HA information pool 13d and the registered contents in the HA2 IP address column of each pool area are registered in advance. Also, the registration content in the status information column of the HA information pool 13d is registered by the control unit 10 every time the DHCP server 1 detects the status of the HAs 2 and 2 connected via the home network N2. Furthermore, the registration contents in the utilization rate column of the HA information pool 13d are as follows: when the DHCP server 1 assigns any HA2 to the DHCP client 4 or releases the assignment of HA2, the assigned HA2 Each time the usage rate is calculated, it is registered by the control unit (acquiring means) 10.

  Thus, in the process of assigning HA2 to each DHCP client 4 based on the registered contents of the HA information pool 13d, the usage rate of each HA2, 2,... Can be taken into account, and the load on HA2, 2,. it can.

  FIG. 5 is a diagram for explaining the configuration of HA2. 5A is a block diagram showing the configuration of HA2, and FIG. 5B is a schematic diagram showing the registration contents of the client information table 23a stored in the memory unit 23 of HA2.

  HA2 is a general home agent for configuring a mobile IP system. The HA 2 includes a control unit 20, a ROM 21, a RAM 22, a memory unit 23, a communication unit 24, and the like, and these hardware units are connected to each other via a bus 2a. The control unit 20 is, for example, a CPU or MPU, and reads a control program stored in advance in the ROM 21 or the memory unit 23 to the RAM 22 as appropriate and executes it. The control unit 20 controls the operation of each hardware unit described above.

The ROM 21 stores various control programs necessary for operating as the HA 2 in advance. The RAM 22 is, for example, an SRAM or a flash memory, and temporarily stores various data generated when the control unit 20 executes the control program.
The memory unit 23 is, for example, a flash memory. The memory unit 23 stores various control programs necessary for operating as the HA2, a client information table 23a as shown in FIG. 5B, and the like.

  In the client information table 23a, as shown in FIG. 5B, for each DHCP client 4, the home address assigned to the DHCP client 4 and the current IP address (care-of address) of the DHCP client 4 are displayed. Are registered in association with each other. 5B shows an example in which the home address 11, the home address 12, and the home address 21 are registered in the home address column, but actually, for example, “3ff: 1: 100 An IP address such as “: 100” is registered. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.100” is registered as the home address.

  The registration contents of the client information table 23a are registered or updated by the control unit 20 every time the HA 2 is notified of the home address and the current IP address from the DHCP client 4. The home address is an IP address assigned by the DHCP server 1 when the DHCP client 4 requests the DHCP server 1 for an IP address. That is, the home address is an address unique to the DHCP client 4 until the address is released.

  The current IP address is an IP address that changes as the DHCP client 4 moves, and is an address that is assigned when the DHCP client 4 moves to an external network other than the home network N2.

  Specifically, the DHCP client 4 receives an agent advertisement (Agent Advertisement) transmitted from the HA2 provided in the home network N2 or an external agent (not shown) provided in an external network other than the home network N2. To do. The DHCP client 4 determines whether it is in the home network N2 or an external network based on the received agent advertisement.

  When detecting that the DHCP client 4 has left the home network N2, the DHCP client 4 acquires the current IP address (care-of address) based on the agent advertisement from the external agent. The DHCP client 4 that has acquired the care-of address in this way notifies the HA 2 of the acquired care-of address (current IP address) and its own home address. Thereby, the control unit 20 of the HA 2 can register the received home address and IP address in the client information table 23a.

  The communication unit 24 is an interface for connecting to the home network N2, and communicates with devices connected to other networks via the home network N2, such as the DHCP server 1 connected to the home network N2.

  When receiving the information (message) transmitted to the home address registered in the client information table 23a, the HA 2 configured as described above identifies the corresponding IP address based on the client information table 23a. The HA 2 functions as a transfer device that transfers the received information to the specified IP address.

  FIG. 6 is a diagram for explaining the configuration of the DHCP relay agent 3. 6A is a block diagram illustrating the configuration of the DHCP relay agent 3, and FIG. 6B is a schematic diagram illustrating the registration contents of the server information table 33a stored in the memory unit 33 of the DHCP relay agent 3. FIG.

  The DHCP relay agent 3 includes a control unit 30, a ROM 31, a RAM 32, a memory unit 33, a first communication unit 34, a second communication unit 35, a wireless communication unit 36, and the like. Are connected to each other. The control unit 30 is, for example, a CPU or an MPU, and reads a control program stored in advance in the ROM 31 or the memory unit 33 to the RAM 32 as appropriate and executes it. The control unit 30 controls the operation of each hardware unit described above.

  The ROM 31 stores in advance various control programs necessary for operating the DHCP relay agent 3 as a relay device (communication device) in the network system according to the present invention. The RAM 32 is, for example, an SRAM or a flash memory, and temporarily stores various data generated when the control unit 30 executes the control program.

  The memory unit 33 is a flash memory, for example. The memory unit 33 stores various control programs necessary for operating the DHCP relay agent 3 as a relay device in the network system according to the present invention, a server information table 33a as shown in FIG. 6B, and the like. . In the server information table (device information storage means) 33a, as shown in FIG. 6B, for each of the DHCP servers 1 and 1, the domain name for identifying the DHCP server 1 and the IP address of the DHCP server 1 ( Device information) is registered in association with each other.

  FIG. 6B shows an example in which the first DHCP server, the second DHCP server, and the third DHCP server are registered in the IP address column of the DHCP servers 1 and 1, but actually, for example, “3ffe : 1: 100 :: 20 "is registered. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.20” is registered as the IP address of the DHCP servers 1 and 1.

  The registered contents of the server information table 33a are registered in advance. The registered contents of the server information table 33a are changed by the administrator via the operation unit (not shown) of the DHCP relay agent 3 when, for example, the domain name or IP address of the DHCP server 1 or 1 is changed. Each time a new domain name or IP address is input, it is updated by the control unit 30.

The first communication unit 34 is an interface for connecting to the IP network N1, and is connected to devices connected to other networks via the IP network N1, such as the DHCP servers 1 and 1 connected to the IP network N1. Communicate.
The second communication unit 35 is an interface for connecting to the wired LAN N3, and communicates with devices connected to other networks via the wired LAN N3, such as the DHCP client 4 connected to the wired LAN N3.

  The wireless communication unit 36 is an interface for connecting to the wireless LAN N4, and communicates with the DHCP client 4 or the like that can be connected to the wireless LAN N4 via the wireless LAN N4.

  FIG. 7 is a block diagram showing the configuration of the DHCP client 4. The DHCP client 4 includes a control unit 40, a ROM 41, a RAM 42, an HDD 43, an operation unit 44, a display unit 45, a communication unit 46, a wireless communication unit 47, and the like. These hardware units are connected to each other via a bus 4a. Has been. The control unit 40 is, for example, a CPU or MPU, and reads a control program stored in advance in the ROM 41 or the HDD 43 into the RAM 42 and executes it. The control unit 40 controls the operation of each hardware unit described above.

  The ROM 41 stores in advance various control programs necessary for operating the DHCP client 4 as a client device (communication device) in the network system according to the present invention. The RAM 42 is, for example, an SRAM or a flash memory, and temporarily stores various data generated when the control unit 40 executes the control program.

  The HDD 43 is a large-capacity storage device. The HDD 43 has various control programs necessary for operating the DHCP client 4 as a client device in the network system according to the present invention, as shown in FIG. 8A, the NAI information table 43a as shown in FIG. The address information table 43b and the like are stored.

  The operation unit 44 includes various operation keys necessary for the user of the DHCP client 4 to operate the DHCP client 4. When the user operates each operation key of the operation unit 44, the operation unit 44 sends a control signal corresponding to the operated operation key to the control unit 40, and the control unit 40 performs processing corresponding to the acquired control signal. Execute.

  The display unit 45 is, for example, a liquid crystal display (LCD), and notifies the operation status of the DHCP client 4, information input via the operation unit 44, and the user according to instructions from the control unit 40. To display information.

  The communication unit 46 includes, for example, a network card and is an interface for connecting to the wired LAN N3. The communication unit 46 communicates with devices connected to other networks via the wired LAN N3, such as the DHCP relay agent 3 and other DHCP clients 4 (not shown) connected to the wired LAN N3.

  The wireless communication unit 47 includes, for example, a network card and is an interface for connecting to the wireless LAN 4 and is connected to an antenna 47a that transmits and receives radio waves for wireless communication. The wireless communication unit 47 communicates with the DHCP relay agent 3 or the like that can be connected to the wireless LAN N4 via the wireless LAN N4. Specifically, the wireless communication unit 47 performs wireless communication with a base station (access point) of the wireless LAN N4 via the antenna 47a in accordance with an instruction from the control unit 40.

  FIG. 8 is a schematic diagram showing registered contents of the NAI information table 43a and the address information table 43b. In the NAI information table (identification information storage means) 43a, as shown in FIG. 8 (a), ISP information for identifying the ISP company and NAI information given by the ISP company are provided for each ISP company. (User identification information) is registered in association with each other. Here, it is assumed that the users of the DHCP client 4 are users of the first ISP provider and the second ISP provider.

  Further, the user of the DHCP client 4 is given the NAI information of “user1@isp1.domain.name” from the first ISP operator and the NAI information of “user1@isp2.domain.name” from the second ISP operator. Suppose that Instead of the ISP information, device information for specifying the DHCP servers 1 and 1 managed by the respective ISP operators may be used.

  The registration contents of the NAI information table 43a are registered by the control unit 40 every time the user inputs ISP information and NAI information via the operation unit 44 when NAI information is given from each ISP provider. The registered contents of the NAI information table 43a are stored in the control unit 40 every time the user inputs the changed NAI information via the operation unit 44 when the NAI information assigned by each ISP is changed. Updated by.

  In the address information table 43b, as shown in FIG. 8B, ISP information, the IP address of the HA 2 assigned by the ISP server's DHCP server 1, the home address, etc. are registered in association with each ISP company. Has been. FIG. 8B shows an example in which HA11 and HA101 are registered in the IP address column of HA2, and home address 11 and home address 101 are registered in the home address column. However, an IP address such as “3ffe: 1: 100 :: 100” is actually registered in each column. If the network system of this embodiment is a mobile IPv4 system, an IP address such as “192.168.100.100” is registered as the home address.

  The registration contents of the address information table 43b are registered or updated by the control unit 40 every time the DHCP client 4 is notified by the HA 2 and home address assigned by the DHCP server 1 of each ISP provider.

  Hereinafter, various processes when the DHCP server 1 assigns an IP address (home address) in accordance with a request from the DHCP client 4 in the network system having the above-described configuration will be described. 9 is a functional block diagram showing the functional configuration of the DHCP client 4, FIG. 10 is a functional block diagram showing the functional configuration of the DHCP relay agent 3, FIG. 11 is a functional block diagram showing the functional configuration of the DHCP server 1, and FIG. FIG. 13 is a schematic diagram showing the content of a response message.

  First, a process in which the DHCP client 4 requests the DHCP server 1 to allocate a home address will be described with reference to FIG. In the DHCP client 4 according to the present embodiment, the control unit 40 executes the control program stored in the ROM 41 or the HDD 43, so that each function of the NAI information selection unit 40a, the request message generation unit 40b, the address registration unit 40c, etc. Is realized. The address registration unit 40c will be described later based on processing in which the DHCP server 1 transmits a response message to the DHCP client 4.

  When using the mobile IPv6 system, the user of the DHCP client 4 needs to be assigned the home address, the IP address of the HA 2, and the like by the DHCP server 1 of any ISP provider. In addition, the user of the DHCP client 4 can request home address assignment for each ISP business operator that is performing the service subscription procedure, and selects the ISP business operator that wants to request home address assignment.

  Specifically, the control unit 40 of the DHCP client 4 displays a list of ISP information registered in the NAI information table 43a and generates a display screen on which one of the displayed ISP information can be selected. It is displayed on the display unit 45. Then, the user selects an ISP operator who desires to request home address assignment via this display screen.

  The operation unit 44 operates as an accepting unit that accepts the selection of the ISP operator selected by the user. The NAI information selection unit (reading unit) 40a reads the NAI information stored in the NAI information table 43a corresponding to the ISP operator selected via the operation unit 44. The NAI information selection unit 40a notifies the request message generation unit 40b of the NAI information read from the NAI information table 43a.

  The request message generation unit (generation means) 40b generates a request message (request signal) for requesting assignment of an IP address as shown in FIG. Specifically, the request message generation unit 40b generates a DUID (DHCP Unique ID) from the MAC address assigned to either the communication unit 46 or the wireless communication unit 47 that transmits the request message. Then, the request message generation unit 40b generates a DHCP message (Information request message) including the NAI information notified from the NAI information selection unit 40a and the generated DUID.

  Here, the case where the request message is transmitted via the communication unit 46 is described as an example, and the DUID based on the MAC address of the network card of the communication unit 46 is “ MACadd1 ”. Further, the request message generation unit 40b sets the current IP address of the DHCP client 4 to the transmission source IP (SourceIP) included in the IP header information of the generated DHCP message. Further, the request message generation unit 40b sets “All_DHCP_Relay_Agents_and_Servers” as the destination of the DHCP relay agent 3 in the destination IP (DestinationIP). The request message generation unit 40 b transmits the generated request message to the DHCP relay agent 3 via the communication unit 46.

  Note that the destination of the DHCP relay agent 3 set as the destination IP is a broadcast IP address in the case of an IPv4 network system, and a multicast DHCP address in the case of an IPv6 network system. That is, it is an address that does not specify the IP address of the DHCP server 1 or 1 for each ISP.

  Next, a process in which the DHCP relay agent 3 transfers a request message transmitted from the DHCP client 4 to the DHCP server 1 will be described with reference to FIG. In FIG. 10, two first communication units 34, two second communication units 35, and two radio communication units 36 are shown for clarity, but they are the same.

  In the DHCP relay agent 3 of the present embodiment, the control unit 30 executes a control program stored in the ROM 31 or the memory unit 33, thereby performing a domain analysis unit 30a, a DHCP server specifying unit 30b, a request message relay unit 30c, Each function such as the response message relay unit 30d is realized. The response message relay unit 30d will be described later based on processing in which the DHCP server 1 transmits a response message to the DHCP client 4.

  In the DHCP relay agent 3, the second communication unit 35 or the wireless communication unit 36 operates as a reception unit that receives a request message from the DHCP client 4. Here, since the DHCP client 4 is transmitting the request message via the wired LAN N3, the second communication unit 35 of the DHCP relay agent 3 receives the request message. The second communication unit 35 transfers the received request message to the domain analysis unit 30a.

  The domain analysis unit 30a analyzes the request message received via the second communication unit 35. Specifically, the domain analysis unit 30a extracts the domain name (realm) in the NAI information included in the DHCP message (Information request message) of the request message. Here, since the request message shown in FIG. 12A is received, the domain analysis unit 30a extracts the domain name “isp1.domain.name”. The domain analyzing unit 30a notifies the extracted domain name to the DHCP server specifying unit 30b.

  The DHCP server specifying unit (specifying unit) 30b specifies the DHCP server 1 corresponding to the domain name notified from the domain analyzing unit 30a. Specifically, the DHCP server specifying unit 30b specifies and reads out the IP address (device information) of the DHCP server 1 registered in the server information table 33a corresponding to the notified domain name. The DHCP server specifying unit 30b notifies the request message relay unit 30c of the IP address of the DHCP server 1 read from the server information table 33a.

  The request message relay unit 30c updates the request message as shown in FIG. 12A received by the second communication unit 35 to the request message as shown in FIG. 12B. Specifically, the request message relay unit 30c adds the IP address of the DHCP client 4 as “Peer-address” to the DHCP message of the request message, and generates a DHCP message (Relay forward message).

  Further, the request message relay unit 30c changes the source IP of the IP header information to the IP address of the DHCP relay agent 3, and the destination IP to the IP address of the DHCP server 1 notified from the DHCP server specifying unit 30b. The request message relay unit 30 c transmits a request message with various information updated to the DHCP server 1 via the first communication unit 34.

  As a result, the DHCP relay agent 3 can transfer the request message from the DHCP client (first communication device) 4 to an appropriate DHCP server (second communication device) 1. Therefore, although the conventional DHCP relay agent 3 cannot switch the transfer destination DHCP server 1 for each request message, it can be realized by the DHCP relay agent 3 of the present embodiment.

  Next, a process in which the DHCP server 1 assigns the home address and the IP address of the HA 2 based on the request message transmitted from the DHCP relay agent 3 will be described with reference to FIG. In the DHCP server 1 of the present embodiment, the control unit 10 executes a control program stored in the ROM 11 or the HDD 13 to thereby perform functions of the NAI information analysis unit 10a, the address issue unit 10b, the response message generation unit 10c, and the like. Is realized.

  In the DHCP server 1, the first communication unit 14 operates as a receiving unit that receives a request message from the DHCP relay agent 3. The first communication unit 14 transfers the received request message to the NAI information analysis unit 10a. The NAI information analysis unit 10 a analyzes the request message received via the first communication unit 14.

  Specifically, the NAI information analysis unit 10a extracts NAI information included in the DHCP message (Relay forward message) of the request message. Here, since the request message shown in FIG. 12B is received, the NAI information analysis unit 10a extracts the NAI information of “user1@isp1.domain.name”. The NAI information analysis unit 10a notifies the extracted NAI information to the address issue unit 10b.

  The address issuing unit 10b searches whether the NAI information notified from the NAI information analyzing unit 10a is registered in the NAI information table 13a. When the NAI information extracted by the NAI information analysis unit 10a is not registered in the NAI information table 13a, this NAI information is not the NAI information of the subscriber of the service provided by the ISP company that manages the DHCP server 1. Accordingly, when the address payout unit 10b determines that the notified NAI information is not registered in the NAI information table 13a, the address payout unit 10b notifies the response message generation unit 10c to that effect without paying out the address.

  On the other hand, when it is determined that the notified NAI information is registered in the NAI information table 13a, the address issuing unit 10b reads the NAI information ID corresponding to the notified NAI information from the NAI information table 13a. Then, the address issuing unit 10b determines whether or not the NAI information ID read from the NAI information table 13a is registered in the user information table 13b.

  When the NAI information ID read from the NAI information table 13a is registered in the user information table 13b, user information (home address, IP address of HA2) is assigned (paid out) to this NAI information before. Indicates that Conversely, when the NAI information ID read from the NAI information table 13a is not registered in the user information table 13b, it indicates that the user information has not been assigned (paid out) to this NAI information before.

  When it is determined that the NAI information ID read from the NAI information table 13a is registered in the user information table 13b, the address issue unit 10b reads the user information of this NAI information ID from the user information table 13b. The address payout unit 10b determines whether or not the same user information as the user information (home address and HA2 IP address) read from the user information table 13b can be repaid. For example, the address payout unit 10b reads the HA2 status information and the utilization rate included in the user information read from the user information table 13b from the HA information pool 13d, and whether or not the same HA2 can be allocated (re-paid). Determine whether.

  Specifically, when the state information of HA2 read from the HA information pool 13d is stopped, or when the utilization rate of HA2 read from the HA information pool 13d is equal to or greater than a predetermined value, the address issuing unit 10b It is determined that the allocation of HA2 is not possible. On the other hand, when the state information of HA2 read from the HA information pool 13d is activated, or when the utilization rate of HA2 read from the HA information pool 13d is less than a predetermined value, the address issuing unit 10b Judge that allocation is possible.

  If the address payout unit 10b determines that the same HA2 can be allocated, the address payout unit 10b notifies the response message generation unit 10c of the user information read from the user information table 13b as user information for re-payout. Thereby, if reassignment of the user information allocated last time is possible, the processing load in the user information assignment processing can be reduced by reassigning the same user information.

  On the other hand, when the address issuing unit 10b determines that the NAI information ID read from the NAI information table 13a is not registered in the user information table 13b, or the NAI information ID read from the NAI information table 13a is the user information table 13b. However, if it is determined that the user information of this NAI information ID cannot be repaid, the user information is paid out for this NAI information ID.

  When the user information registered in the user information table 13b cannot be re-paid out, the user pays out the user information, that is, the release of the previously assigned user information. To do. Specifically, the address issuing unit 10b extracts the pool area information and home address of the home address pool 13c included in the user information read from the user information table 13b. The address issuing unit 10b adds the extracted home address to the pool area of the home address pool 13c indicated by the extracted pool area information.

  Then, the address payout unit 10b deletes the user information read from the user information table 13b from the user information table 13b. As a result, the home address assigned by this user information is released to other users, so that resources can be used effectively.

  In addition, as a situation where re-payment of user information is not possible, in addition to the case where HA 2 is in a stopped state, for example, the expiration date of use of user information set at the time when user information was assigned last time can be considered. In this case, there is a possibility that the HA2 assigned last time is in the activated state at the present time. If the HA2 is in the activated state, the HA2 also needs to be released to other users.

  As a process of releasing the allocation of HA2, the address issuing unit 10b extracts the pool area information of the HA information pool 13d and the IP address of HA2 included in the user information read from the user information table 13b. The address issuing unit 10b specifies HA information including the extracted HA2 IP address from the HA information registered in the pool area of the HA information pool 13d indicated by the extracted pool area information. If the status information of the identified HA information is “activated”, the address issuing unit 10b updates the specified HA information by subtracting a predetermined number from the utilization rate. Thereby, since the utilization rate of HA2 allocated by this user information can be updated, it can be reflected in the subsequent allocation process of HA2.

  Next, a user information payout process by the address payout unit 10b will be described. The address payout unit (assignment means) 10b assigns a home address and HA2 to one NAI information by performing a user information payout process. Specifically, when assigning home addresses, the address issuing unit 10b selects one of the pool areas of the home address pool 13c, and selects one of the home addresses pooled in the selected pool area. .

  As a method of selecting an arbitrary home address from the home address pool 13c, for example, by checking home addresses pooled in order from the first pool area and detecting a usable home address, the home address can be selected. Good.

  Further, when allocating HA2, the address issuing unit 10b selects one of the pool areas of the HA information pool 13d, and selects any HA2 in which HA information is pooled in the selected pool area. As a method for selecting an arbitrary HA 2 from the HA information pool 13d, for example, the status information and the utilization rate of the HA information pooled in order from the first pool area are checked, and the utilization rate is less than a predetermined value during activation. If HA2 can be detected, the HA2 may be selected. In this way, by selecting and assigning HA2 having a utilization rate less than a predetermined value, the load on HA2, 2,... Can be distributed.

  The address issuing unit 10b selects the home address selected based on the home address pool 13c, the pool area information indicating the pool area of the home address, the IP address of the HA2 selected based on the HA information pool 13d, and the HA information of the HA2 Pool area information indicating the pool area is registered in the user information table 13b in association with the NAI information ID. As a result, the user information assigned to each NAI information (the pool area information of the home address pool 13c, the home address, the pool area information of the HA information pool 13d, and the IP address of HA2) can be reliably managed.

  The address issuing unit 10b can avoid duplicate assignment of the same home address by deleting the home address read from the home address pool 13c from the home address pool 13c. Further, the address payout unit 10b adds a predetermined number to the utilization rate of HA2 selected based on the HA information pool 13d and updates the HA information pool 13d. As a result, the utilization rate obtained by allocating HA2 to new NAI information can be reflected in the next allocation process.

  Through the above-described processing, the DHCP server 1 of the present embodiment reassigns the same user information if the user information assigned last time can be reassigned to the same NAI information. Therefore, the processing load in the user information allocation process can be reduced. In addition, user information can be reliably assigned to NAI information for which user information has not been assigned before, or NAI information for which reassignment of previously assigned user information is not possible.

  Further, the DHCP server 1 according to the present embodiment confirms whether or not reassignment of user information assigned last time is possible based on the HA information pool 13d. Thus, for example, when a failure occurs in HA2, 2,... Or when maintenance inspection is performed, even when HA2 assigned last time becomes unavailable, a different HA2 can be reassigned.

  The address issuing unit 10b notifies the response message generating unit 10c of the home address and the HA2 IP address in the issued user information. The response message generator 10c generates a response message as shown in FIG. Specifically, the response message generator 10c receives the DHCP address of the request message shown in FIG. 12B received by the first communication unit 14 and the home address and HA2 issued by the address issuer 10b. An IP address is added to generate a DHCP message (Relay reply message).

  Further, the response message generation unit 10c sets the transmission source IP of the IP header information of the response message to the IP address of its own DHCP server 1, and sets the transmission destination IP to the IP address of the DHCP relay agent 3. The response message generation unit 10 c transmits the generated response message to the DHCP relay agent 3 via the first communication unit 14.

  The response message generator 10c is notified that the address cannot be issued from the address issuing unit 10b, that is, the NAI information described in the request message has not been registered in the NAI information table 13a. In this case, an error notification message is generated to notify that the address cannot be paid out. Then, the address payout unit 10 b transmits the generated error notification message to the DHCP relay agent 3 via the first communication unit (transmission unit) 14.

  As shown in FIG. 10, in the DHCP relay agent 3, the first communication unit 34 receives a response message from the DHCP server 1. The first communication unit 34 transfers the received response message to the response message relay unit 30d. The response message relay unit 30d updates the response message received through the first communication unit 34 shown in FIG. 13 (a) to the response message shown in FIG. 13 (b) via the second communication unit 35. Transmit to the DHCP client 4.

  Specifically, the response message relay unit 30d changes the destination IP of the IP header information of the response message to Peer-address (IP address of the DHCP client 4) in the DHCP message, and changes the source IP to its own DHCP. Change to the IP address of relay agent 3. Further, the response message relay unit 30d deletes the peer-address from the DHCP message (Relay reply message) of the received response message and generates a DHCP message (Reply message).

  As shown in FIG. 9, in the DHCP client 4, the communication unit 46 receives the response message relayed from the DHCP relay agent 3. The communication unit 46 transfers the received response message to the address registration unit 40c. The address registration unit 40c analyzes the response message received via the communication unit 46, and determines whether or not the response message is an error notification message.

  When the address registration unit 40c determines that the response message is an error notification message, the control unit 40 of the DHCP client 4 generates and displays an error notification screen for notifying that the address has not been issued. Display on the unit 45. Thereby, the user of the DHCP client 4 can grasp that the assignment of the home address and the HA 2 has failed.

  If the address registration unit 40c determines that the response message is not an error notification message, the address registration unit 40c extracts the home address and the HA2 IP address described in the DHCP message (Reply message) of the response message. The address registration unit 40c registers the extracted home address and the IP address of HA2 in the address information table 43b in association with the ISP information of the DHCP server 1.

  As described above, by registering the home address notified by the response message and the IP address of HA2 in the address information table 43b, the control unit 40 allows the home address assigned by each DHCP server 1, 1 and The IP address of HA2 can be managed for each ISP company.

  The control unit 40 of the DHCP client 4 uses the home address registered in the address information table 43b and the current IP address (care-of address) acquired as necessary as the IP address of HA2 registered in the address information table 43b. Based on the above, the HA2 assigned to itself is notified. The control unit 20 of the HA 2 registers the home address and IP address notified from the DHCP client 4 in the client information table 23a, and registers the location of the DHCP client 4 in the mobile IPv6 system.

  In this way, by registering the home address and IP address of the DHCP client 4 in the HA 2, the information transmitted to the home address of the DHCP client 4 is transmitted by the HA 2 to the IP address (care-of address) of the DHCP client 4. It is forwarded to. Specifically, when receiving the information addressed to the home address of the DHCP client 4, the control unit 20 of the HA 2 reads the IP address (care-of address) corresponding to the home address from the client information table 23a. Then, the control unit 20 transfers the information transmitted to the home address to the read IP address.

  Therefore, even when the DHCP client 4 leaves the home network N2 and the IP address is changed, information addressed to the DHCP client 4 is reliably transmitted to the DHCP client 4. Note that the control unit 40 of the DHCP client 4 can detect whether or not it has exited from the home network N2 based on the agent advertisement transmitted from the HA2 provided in the home network N2 or the external agent provided in the external network. It is configured as follows.

  Further, when the control unit 40 detects that it has left the home network N2, the control unit 40 acquires the current IP address (care-of address) based on the agent advertisement from the external agent. Then, each time the control unit 40 acquires the care-of address, the control unit 40 notifies the HA 2 of the acquired care-of address (current IP address) and its own home address. As a result, the HA 2 can always know the IP address of the DHCP client 4 and can reliably transfer the information transmitted to the home address of the DHCP client 4 to the DHCP client 4.

  In the network system of the present embodiment, as described above, the DHCP server 1 assigns a home address and HA2 for each NAI information in the request message transmitted from the DHCP client 4. Therefore, even if the user switches from communication via the wired LAN N3 to communication via the wireless LAN N4 in the DHCP client 4 to which the home address and HA2 are assigned by the DHCP server 1, the NAI information is the same. As such, the same home address and HA2 are reassigned. That is, the user of the DHCP client 4 can use the same home address and HA2.

  Specifically, when using the service of the ISP operator assigned the home address and HA2 via the wireless communication unit 47 according to the request message transmitted via the communication unit 46 of the DHCP client 4, DHCP is used. The client 4 transmits a similar request message to the DHCP server 1 via the wireless communication unit 47. Here, since the request message is transmitted via the wireless communication unit 47, the DUID based on the MAC address of the network card of the wireless communication unit 47 is described in the DHCP message of the request message shown in FIG. The

  Such a request message is transmitted to the DHCP server 1 via the DHCP relay agent 3. Similar to the above-described processing, the DHCP server 1 performs home address and HA2 allocation processing according to the received request message, generates a response message, and transmits the response message to the DHCP client 4 via the DHCP relay agent 3. Note that the DHCP server 1 of the present embodiment assigns a home address and HA2 for each NAI information included in the request message, so that the same home address and HA2 are again assigned to a request message whose DUID has only been changed. To be paid out.

  In the DHCP server 1, when it is determined that the same home address and HA2 can be re-paid, it is determined that the home address and HA2 are different.

  Therefore, the same home address and HA2 can be used even when switching between different media is performed, such as when switching from wired LAN N3 to wireless LAN N4. Therefore, seamless transition between different access networks in the mobile IP system is possible. In addition, since it is possible to prevent overlapping assignment of different IP addresses to substantially the same user, it is necessary to consider the case where IP addresses (home addresses) are assigned to different media for substantially the same user. There is no need to reserve resources. Therefore, there is no possibility that the IP address is exhausted, and the network management cost can be reduced.

  In this way, by paying out unique resources for each user, mobile IP resource payout can be realized using DHCP without reducing the work of the network administrator and the convenience of the user, which are the features of DHCP. be able to.

  In the network system of the present embodiment, the processing when switching from the wired LAN N3 to the wireless LAN N4 has been described. However, the network system according to the present invention is not limited to such a case, and the same home address and HA2 can be used even when switching between other media is performed.

  Examples of media to be switched in the mobile IPv6 system include analog telephone communication media, ISDN (Integrated Service Digital Network) telephone communication media, and the like in systems configured by wire. In a system configured by radio, for example, PDC (Personal Digital Cellular) data communication media, W-CDMA (Wideband-Code Division Multiple Access) / CDMA2000 data communication media, PHS (Personal Handy-phone System) method, for example. Data communication media, WiMAX (Worldwide Interoperability for Microwave Access) type data communication media, and the like can be mentioned.

  Hereinafter, processing when the DHCP server 1 assigns an IP address (home address) according to a request from the DHCP client 4 in the network system described above will be described based on a flowchart. FIG. 14 to FIG. 17 are flowcharts showing the procedure of address payout processing. The following processing is executed by the control unit 10 according to the control program stored in the ROM 11 or the HDD 13 of the DHCP server 1 and by the control unit 20 according to the control program stored in the ROM 21 or the memory unit 23 of the HA 2. Executed.

  The following processing is executed by the control unit 30 according to the control program stored in the ROM 31 or the memory unit 33 of the DHCP relay agent 3 and controlled according to the control program stored in the ROM 41 or the HDD 43 of the DHCP client 4. This is executed by the unit 40. In FIG. 14, in the three areas separated by broken lines, the processing by the DHCP client 4 is shown in the left area, the processing by the DHCP relay agent 3 is shown in the center area, and the processing by the DHCP server 1 is shown in the right area. ing.

  In FIG. 15, in the two areas separated by the broken line, the process by the DHCP relay agent 3 is shown in the left area, and the process by the DHCP server 1 is shown in the right area. In FIG. 16, in the two areas separated by a broken line, the process by the DHCP relay agent 3 is shown in the left area, and the process by the DHCP server 1 is shown in the right area. Further, in FIG. 17, in the three areas separated by broken lines, the processing by HA2 is shown in the left area, the processing by the DHCP client 4 is shown in the center area, and the processing by the DHCP relay agent 3 is shown in the right area. .

  The control unit 40 of the DHCP client 4 determines whether or not the selection of the ISP company has been accepted by the operation of the operation unit 44 by the user (S1). When it is determined that the selection has not been accepted (S1: NO), the control unit 40 stands by while performing other processes until the selection of the ISP company is accepted.

  When the control unit 40 of the DHCP client 4 determines that the selection of the ISP provider has been accepted (S1: YES), the NAI information corresponding to the selected ISP provider is read from the NAI information table 43a (S2). The control unit 40 generates a request message as shown in FIG. 12A based on the NAI information read from the NAI information table 43a, and transmits it to the DHCP relay agent 3 via the communication unit 46 or the wireless communication unit 47. (S3).

  The control unit 30 of the DHCP relay agent 3 receives the request message transmitted from the DHCP client 4 via the second communication unit 35 or the wireless communication unit 36 (S4). The control unit 30 extracts the domain name in the NAI information included in the DHCP message of the received request message (S5), and specifies the DHCP server 1 corresponding to the extracted domain name (S6). The control unit 30 reads the IP address of the specified DHCP server 1 from the server information table 33a, updates the request message received in step S4 according to the read IP address, and sends it to the DHCP server 1 via the first communication unit 34. Transmit (S7).

  The control unit 10 of the DHCP server 1 receives the request message transmitted from the DHCP relay agent 3 via the first communication unit 14 (S8). The control unit 10 extracts NAI information included in the DHCP message of the received request message (S9), and determines whether or not the extracted NAI information is registered in the NAI information table 13a (S10). If the control unit 10 determines that the address is not registered in the NAI information table 13a (S10: NO), the control unit 10 generates an error notification message notifying that the address cannot be paid out, and via the first communication unit 14 Transmit to the DHCP relay agent 3 (S11). In addition, after the process of step S11, it transfers to step S19.

  When the control unit 10 of the DHCP server 1 determines that the extracted NAI information is registered in the NAI information table 13a (S10: YES), the NAI information ID corresponding to this NAI information is read from the NAI information table 13a ( S12). The control unit 10 determines whether or not user information including the read NAI information ID is registered in the user information table 13b (S13).

  When it is determined that the user information is registered in the user information table 13b (S13: YES), the control unit 10 of the DHCP server 1 reads out the user information from the user information table 13b (S14). The control unit 10 determines whether or not the user information (home address and HA2 IP address) read from the user information table 13b can be repaid (S15).

  When the control unit 10 of the DHCP server 1 determines that the user information can be repaid (S15: YES), the user information read from the user information table 13b is used as the repaid user information. Then, the control unit 10 generates a response message (Relay reply message) as shown in FIG. 13A based on the home address and the IP address of the HA 2 included in the re-payout user information, and the first communication unit 14 to the DHCP relay agent 3 (S18).

  When the control unit 10 of the DHCP server 1 determines that re-payment of user information is not possible (S15: NO), the home address and HA2 assigned previously are assigned based on the user information read in step S14. Release (S16). When the previously allocated home address and HA2 allocation is released, or when it is determined that the user information is not registered in the user information table 13b (S13: NO), the control unit 10 extracts the NAI extracted in step S9. User information for information is paid out (S17). Specifically, the control unit 10 assigns a home address and HA2 to the NAI information extracted in step S9.

  Then, the control unit 10 generates a response message (Relay reply message) as shown in FIG. 13A based on the issued user information (home address, HA2 IP address), and the first communication unit 14 To the DHCP relay agent 3 (S18).

  The control unit 30 of the DHCP relay agent 3 receives the response message transmitted from the DHCP server 1 via the first communication unit 34 (S19). The control unit 30 updates the received response message and transfers (transmits) it to the DHCP client 4 via the second communication unit 35 or the wireless communication unit 36 (S20).

  The control unit 40 of the DHCP client 4 receives the response message transmitted from the DHCP relay agent 3 via the communication unit 46 or the wireless communication unit 47 (S21). The control unit 40 determines whether or not the received response message is an error notification message (S22). When the control unit 40 determines that the message is an error notification message (S22: YES), the control unit 40 generates an error notification screen notifying that the address has not been paid out and displays the error notification screen on the display unit 45 (S23). Exit.

  When the control unit 40 of the DHCP client 4 determines that the message is not an error notification message (S22: NO), the home address notified by the response message and the IP address of the HA2 are associated with the ISP information of the DHCP server 1 and addressed. Register in the information table 43b (S24). The control unit 40 notifies the home address registered in the address information table 43b and the current IP address of the DHCP client 4 to the HA2 indicated by the IP address of the HA2 registered in the address information table 43b (S25). Note that the current IP address of the DHCP client 4 is sequentially updated and stored in the RAM 12 or the like.

  The control unit 20 of the HA 2 registers the home address and IP address notified from the DHCP client 4 in the client information table 23a (S26), and ends the above-described address payout process.

  As described above, the DHCP server 1 according to the present embodiment assigns the home address and the HA 2 for each NAI information in the request message transmitted from the DHCP client 4. Therefore, even when the communication medium is changed in the DHCP client 4, the same home address and HA2 can be used, so that seamless transition between different access networks in the mobile IP system is possible.

  In addition, since the home address and HA2 are allocated for each NAI information, it is possible to prevent overlapping allocation of different home addresses and HA2 to substantially the same user. Therefore, it is not necessary to reserve surplus resources in consideration of the case where an IP address (home address) is assigned to the same user for each different medium. Therefore, there is no possibility that the IP address is exhausted, and the HA2 is effectively used, so that the network management cost can be reduced.

  In the above-described embodiment, the ISP operator is configured to manage one DHCP server 1, and the DHCP relay agent 3 specifies the DHCP server 1 to which the request message should be transferred according to the domain name included in the received request message. It was the composition to do. In addition to such a configuration, each ISP may be configured to manage a plurality of DHCP servers 1. In this case, for example, the ISP provider further includes a management server that manages the load states of the plurality of DHCP servers 1 that it manages. Then, the DHCP relay agent 3 specifies the ISP operator according to the domain name included in the received request message, and transfers the request message to the management server of the specified ISP operator.

  The management server of the ISP provider specifies the DHCP server 1 to which the received request message is to be transferred based on the load state of the DHCP server 1 managed by its ISP provider, and requests the specified DHCP server 1 Just forward the message. With this configuration, the load on each DHCP server 1 managed by one ISP provider can be distributed according to the round robin method.

  In the embodiment described above, the DHCP server 1 and the HAs 2 and 2 managed by the same ISP provider are connected to the same home network N2. In addition, the DHCP servers 1 and 1 and the DHCP relay agent 3 managed by each ISP operator are connected to the IP network N1, and the DHCP relay agent 3 and the DHCP client 4 are connected to the wired LAN N3 and the wireless LAN N4. It was. In addition to this configuration, for example, all of the DHCP servers 1, 1, HA2, 2,..., The DHCP relay agent 3, and the DHCP client 4 may be connected to the Internet.

  In the above-described embodiment, the DHCP servers 1 and 1 are configured to allocate a home address and one of the HAs 2 to the request message from the DHCP client 4. In addition to such a configuration, the DHCP server 1 or 1 starts or continues communication or various services in the mobile IP environment by the user of the DHCP client 4 such as an SIP server, DNS server, or NTP server with respect to the DHCP client 4. It is also possible to configure so as to assign information necessary for this.

  In this case, the DHCP servers 1 and 1 include a SIP server information pool including server information, status information, usage rate, and the like in each of the plurality of SIP servers, as in the configuration of the HA information pool 13d. The SIP server may be allocated based on the registered contents. Further, the DHCP servers 1 and 1 are provided with a DNS server information pool including server information, status information, usage rate, and the like in each of a plurality of DNS servers, and DNS servers are allocated based on the registered contents of the DNS server information pool. Just do it.

  Further, the DHCP servers 1 and 1 have an NTP server information pool including server information, status information, usage rate, etc. in each of a plurality of NTP servers, and assign NTP servers based on the registered contents of the NTP server information pool. Just do it. In this case, the IP addresses of the SIP server, DNS server, and NTP server assigned to the DHCP client 4 are registered in the user information table 13b and notified to the DHCP client 4 by a response message.

  Regarding the above-described embodiment, the following additional notes are disclosed.

(Appendix 1)
In a network system in which a server device assigns an IP (Internet Protocol) address according to a request from a client device connected via a network,
The client device includes means for transmitting a request signal for requesting assignment of an IP address to the server device via the network, including user identification information for identifying a user of the device.
The server device
Receiving means for receiving the request signal;
Assigning means for assigning an IP address for each user identification information included in the request signal received by the receiving means;
A network system comprising: a transmission unit that transmits the IP address allocated by the allocation unit to the client device that has transmitted the request signal.

(Appendix 2)
Comprising a relay device connected to the client device and the server device via the network;
The relay device
Receiving means for receiving the request signal from the client device;
Specifying means for specifying a server device to which the request signal received by the receiving means is transferred;
The network system according to appendix 1, further comprising means for transferring the request signal to the server device specified by the specifying means.

(Appendix 3)
The user identification information includes a domain name assigned to the client device,
The relay device specifying means is configured to specify a transfer destination server device based on a domain name in user identification information included in a request signal received by the receiving means. 2. The network system according to 2.

(Appendix 4)
The network system according to any one of appendices 1 to 3, wherein the IP address assigned by the assigning unit of the server device is a home address of the client device.

(Appendix 5)
A plurality of home agents that transfer information sent to the home address of the client device to a care-of address that is a destination address of the client;
The server device
An acquisition means for acquiring load information in each home agent;
Means for selecting one of a plurality of home agents based on the load information acquired by the acquisition unit when the reception unit receives a request signal;
The allocating unit of the server device is configured to allocate a home address of the client device and a selected home agent for each user identification information included in the request signal received by the receiving unit. The network system according to appendix 4.

(Appendix 6)
In a communication device that assigns an IP address according to a request from another communication device connected via a network,
Receiving means for receiving a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the other communication apparatus from the other communication apparatus;
Assigning means for assigning an IP address for each user identification information included in the request signal received by the receiving means;
A communication device comprising: a transmission unit that transmits the IP address allocated by the allocation unit to the other communication device that has transmitted the request signal.

(Appendix 7)
The communication apparatus according to appendix 6, wherein the IP address assigned by the assigning unit is a home address of the other communication apparatus.

(Appendix 8)
Acquisition means for acquiring load information in each of a plurality of transfer devices that transfer information transmitted to a home address of the other communication device to a care-of address that is a destination address of the other communication device;
Means for selecting one of a plurality of transfer devices based on the load information acquired by the acquisition means when the reception means receives a request signal;
The allocating unit is configured to allocate a home address of the other communication device and a selected transfer device for each user identification information included in the request signal received by the receiving unit. The communication apparatus according to appendix 7.

(Appendix 9)
In a communication device that requests assignment of an IP address to another communication device connected via a network,
Generating means for generating a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the device;
Means for transmitting the request signal generated by the generating means to the other communication apparatus via the network.

(Appendix 10)
Device information for identifying each of a plurality of other communication devices, and identification information storage means for storing each of a plurality of user identification information in association with each other;
Accepting means for accepting selection of any of a plurality of other communication devices;
Reading means for reading out the user identification information stored in the identification information storage means corresponding to the other communication device for which the reception means has accepted the selection,
The communication apparatus according to appendix 9, wherein the generation unit is configured to generate a request signal including user identification information read from the identification information storage unit by the reading unit.

(Appendix 11)
In a communication device for transferring a signal from a first communication device received via a network to a second communication device,
Receiving means for receiving a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the first communication device, from the first communication device;
Specifying means for specifying the second communication device to which the request signal received by the receiving means is transferred;
And a means for transferring the request signal to the second communication apparatus specified by the specifying means.

(Appendix 12)
The user identification information includes a domain name assigned to the first communication device,
Device information storage means for storing each of a plurality of domain names and device information for specifying each of the plurality of second communication devices in association with each other;
The specifying unit is configured to transfer the second communication device as a transfer destination based on the device information stored in the device information storage unit corresponding to the domain name in the user identification information included in the request signal received by the receiving unit. The communication apparatus according to appendix 11, wherein the communication apparatus is configured to specify

(Appendix 13)
In an allocation method in which a server device assigns an IP address in accordance with a request from a client device connected via a network,
The client device includes a user identification information for identifying a user of its own device, and transmits a request signal for requesting an IP address assignment to the server device via the network;
An assignment step in which the server device assigns an IP address for each user identification information included in the received request signal;
The server apparatus includes the step of transmitting the IP address allocated in the allocation step to the client apparatus that has transmitted the request signal.

(Appendix 14)
In a computer program for causing a computer to assign an IP address in accordance with a request from an external device connected via a network,
In the computer,
Extracting user identification information for identifying a user of the external device included in a request signal for requesting assignment of an IP address received from the external device;
A computer program for executing an assigning step of assigning an IP address for each extracted user identification information.

It is a schematic diagram which shows the structure of a network system. It is a block diagram which shows the structure of a DHCP server. It is a schematic diagram which shows the registration content of a NAI information table and a user information table. It is a schematic diagram which shows the registration content of a home address pool and a HA information pool. It is a figure for demonstrating the structure of HA. It is a figure for demonstrating the structure of a DHCP relay agent. It is a block diagram which shows the structure of a DHCP client. It is a schematic diagram which shows the registration content of a NAI information table and an address information table. It is a functional block diagram which shows the function structure of a DHCP client. It is a functional block diagram which shows the function structure of a DHCP relay agent. It is a functional block diagram which shows the function structure of a DHCP server. It is a schematic diagram which shows the content of a request message. It is a schematic diagram which shows the content of a response message. It is a flowchart which shows the procedure of an address payout process. It is a flowchart which shows the procedure of an address payout process. It is a flowchart which shows the procedure of an address payout process. It is a flowchart which shows the procedure of an address payout process.

Explanation of symbols

1 DHCP server (server device, communication device)
10 Control unit 10b Address issuing unit (allocation means)
14 1st communication part (reception means, transmission means)
2 HA (transfer equipment)
3 DHCP relay agent (relay device, communication device)
30 control unit 30b DHCP server identification unit (identification means)
33a Server information table (device information storage means)
35 Second communication unit (reception means)
36 Wireless communication unit (reception means)
4 DHCP client (client device, communication device)
40 control unit 40a NAI information selection unit (reading means)
40b Request message generator (generator)
43a NAI information table (identification information storage means)
44 Operation part (reception means)

Claims (7)

In a network system in which a server device assigns an IP (Internet Protocol) address according to a request from a client device connected via a network,
A plurality of home agents that transfer information sent to the IP address of the client device to a care-of address that is a destination address of the client device;
The client device includes means for transmitting a request signal for requesting assignment of an IP address to the server device via the network, including user identification information for identifying a user of the device.
The server device
An acquisition means for acquiring load information in each home agent;
Receiving means for receiving the request signal;
Means for selecting one of a plurality of home agents based on the load information acquired by the acquisition means when the reception means receives the request signal;
Assigning means for assigning the IP address of the client device and the selected home agent for each user identification information included in the request signal received by the receiving means ;
A network system comprising: a transmission unit that transmits information indicating the IP address and home agent allocated by the allocation unit to the client device that has transmitted the request signal. Comprising a relay device connected to the client device and the server device via the network;
The relay device
Receiving means for receiving the request signal from the client device;
Specifying means for specifying a server device to which the request signal received by the receiving means is transferred;
2. The network system according to claim 1, further comprising means for transferring the request signal to the server device specified by the specifying means. The user identification information includes a domain name assigned to the client device,
The relay device specifying means is configured to specify a transfer destination server device based on a domain name in user identification information included in a request signal received by the receiving means. Item 3. The network system according to Item 2.   The network system according to any one of claims 1 to 3, wherein the IP address assigned by the allocating unit of the server device is a home address of the client device. In a communication device that assigns an IP address according to a request from another communication device connected via a network,
Acquisition means for acquiring load information in each of a plurality of home agents that transfer information transmitted to the IP address of the other communication device to a care-of address that is a destination address of the other communication device;
Receiving means for receiving a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the other communication apparatus from the other communication apparatus;
Means for selecting one of a plurality of home agents based on the load information acquired by the acquisition means when the reception means receives the request signal;
An allocating unit for allocating the IP address of the other communication device and the selected home agent for each user identification information included in the request signal received by the receiving unit ;
A communication apparatus comprising: a transmission means for transmitting information indicating the IP address and home agent assigned by the assignment means to the other communication apparatus that has transmitted the request signal. In a communication device that requests assignment of an IP address to another communication device connected via a network,
Generating means for generating a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the device;
Means for transmitting the request signal generated by the generating means to the other communication device via the network ;
A home agent that transfers the IP address assigned by the other communication device based on the request signal and the information transmitted to the IP address of the own device to the care-of address that is the destination address of the own device. Means for receiving information indicating the communication device. In a communication device for transferring a signal from a first communication device received via a network to a second communication device,
Receiving means for receiving a request signal for requesting assignment of an IP address, including user identification information for identifying a user of the first communication device, from the first communication device;
Specifying means for specifying the second communication device to which the request signal received by the receiving means is transferred;
Means for transferring the request signal to the second communication device specified by the specifying means ;
The IP address assigned by the second communication device based on the request signal and the information transmitted to the IP address of the first communication device are addressed to the care-of address that is the destination address of the first communication device. A communication apparatus comprising: means for transferring information indicating a home agent to be transferred from the second communication apparatus to the first communication apparatus.

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