Patent Publication Number: US-2002006133-A1

Title: Communications service providing system, and mobile terminal device, address server device, and router device for use therewith

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a system and method for providing a mobile communications service in a network using an IP, and more specifically to a system, a method, a mobile terminal device, and a router device for providing a mobile communications service in a network supporting an IPv6.  
       [0003] 2. Description of the Related Art  
       [0004] Recently, with the remarkable progress of Internet, the IP packet traffic has largely increased. In addition, with an increasing number of portable telephones, IMT-2000 (International Mobile Telecommunications 2000) has been standardized, and it is expected that a high-speed IP communications service and a value added service will be popularized in a mobile environment.  
       [0005] However, when a communications service is provided for a mobile node in a mobile environment, it is basically necessary to set predetermined information in a communications appliance (for example, a router device) which accommodates the mobile node. Especially, when a value added service is provided for a mobile node, specific information has to be set for each mobile node. However, since a mobile node tends to move to an arbitrary location, there are a large number of communications appliances which can accommodate mobile nodes. That is, when a communications service is provided for in a mobile environment, it is necessary to set specific information in each mobile node for an enormously large number of communications appliances.  
       [0006] Under such situation, the Applicant of the present invention has suggested a method for solving the above mentioned problems. The method suggested to solve the above mentioned problems is described below by referring to FIGS. 1 and 2.  
       [0007]FIG. 1 shows the configuration of an existing common mobile IP network. In the network shown in FIG. 1, a home network  1  managed by a service provider of a mobile node (MN)  11  and foreign networks  2  through  4  managed by another service provider are interconnected through an IP network  5 .  
       [0008] With the above mentioned configuration, the necessary information (service control information or service profile) for use in providing a communications service for the mobile node  11  is stored in a database  13  (SPDB) accessible by an AAAH (authentication, authorization, and accounting home) server  12 . When the mobile node  11  moves from the communications area of the foreign network  2  to the communications area of the foreign network  3 , the AAAH server  12  extracts the service control information corresponding to the mobile node  11  from the database  13 , and sends it to a foreign agent (FA)  14 . Afterwards, a communications service is provided for the mobile node  11  according to the service control information.  
       [0009]FIG. 2 shows the location registration sequence of a mobile node in an existing system. This sequence is executed when, for example, the mobile node  11  enters the communications area of the foreign agent  14  as shown in FIG. 1. The mobile IP protocol is used between the mobile node  11  and the foreign agent  14 . In addition, the DIAMETER protocol, which is known as one of the AAA protocols, is used among the foreign agent  14 , an AAAF  15 , the AAAH server  12 , and a home agent  16 .  
       [0010] When the mobile node  11  receives an advertisement message periodically output from the foreign agent  14 , it transmits a registration request message to the foreign agent  14 . When the foreign agent  14  receives the registration request message, it transmits an AMR (AA-mobile-node-request) message to the AAAF (authentication, authorization, and accounting foreign) server  15 . The AAAF  15  performs authenticating, authorizing, and accounting processes for the user in contract with a service provider for managing the foreign network  3 . That is, the AAAF  15  cannot perform the authenticating, authorizing, and accounting processes for the mobile node  11 . Therefore, when the AAAF  15  receives the AMR message from the foreign agent  14 , it transfers the message to the AAAH server  12 .  
       [0011] When the AAAH server  12  receives the AMR message, it performs the authenticating, authorizing, and accounting processes for the mobile node  11 , and extracts the service control information corresponding to the mobile node  11  from the database  13 . Then, the AAAH server  12  transmits an HAR (home-agent-MIP-request) message to the home agent (HA)  16 . At this time, the HAR message stores the service control information extracted from the database  13 . Thus, the service control information corresponding to the mobile node  11  is distributed to the home agent  16 . Then, after the home agent  16  registers the location about the mobile node  11 , it returns a HAA (home-agent-MIP-answer) message to the AAAH server  12 .  
       [0012] When the AAAH server  12  receives the HAA message, it transmits an AMA (AA-mobile-node-answer) message to the AAAF  15 . At this time, the AMA message stores the service control information corresponding to the mobile node  11 . In addition, when the AAAF  15  receives the AMA message, it transfers the message to the foreign agent  14 . As a result, the service control information corresponding to the mobile node  11  is distributed to the AAAF  15  and the AAAH server  12 . Then, a registration reply message is returned from the foreign agent  14  to the mobile node  11 , thereby terminating the location registration sequence.  
       [0013] Thus, in the method suggested by the Applicant of the present invention, the service control information about the mobile node is automatically distributed to a predetermined communications appliance during the location registration procedure. As a result, the corresponding service control information can be set for the minimal communications appliances.  
       [0014] With the popularization of Internet, the available addresses are running short in the IPv4 (IP version 4). Therefore, in the IP communications at present, the IPv4 is being switched to the IPv6 (IP version 6). However, up to now, the technology of providing a value added service using the IPv6 has not been sufficiently studied, and there are a number of problems to be solved.  
       [0015] For example, although it is necessary to support an IPsec (IP security protocol) in the IPv6, the sequence described above by referring to FIG. 2 cannot be followed in the network in which the IPsec is supported. This problem is described below by referring to FIGS. 3 and 4. The IPsec contains an authentication protocol and an encryption protocol, and functions as a protocol for guaranteeing the security in the IP layer.  
       [0016]FIG. 3 shows a packet transmitted in the location registration sequence shown in FIG. 2. As shown in FIG. 3, the information transmitted through the IP network is basically stored in an IP packet. The IP packet includes an IP header and an IP payload storing a UDP packet. The UDP packet includes a UDP header and a UDP payload, and the UDP payload stores information relating to the location registration sequence. Here, in FIG. 3, the “Mobile IP” corresponds to, for example, a registration request message, a registration reply message, etc. The “AAA” corresponds to, for example, an AMR message, an AMA message, an HAR message, an HAA message, etc. Therefore, a foreign agent (FA), an AAAF server, an AAAH server, and a home agent (HA) extract necessary information from the UDP payload stored in the received IP packet, and perform the process relating to the location registration sequence.  
       [0017] However, in a system which supports the IPsec, each IP packet is encrypted and transmitted as shown in FIG. 4. Practically, an IP payload is encrypted. At this time, it is obvious that the information relating to the location registration sequence stored in the UDP packet is also encrypted. Therefore, the foreign agent (FA), the AAAF server, the AAAH server, and the home agent (HA) cannot decode the information relating to the location registration sequence. As a result, the sequence shown in FIG. 2 cannot be executed.  
       [0018] Furthermore, although the conventional mobile IP network has been configured based on the function entity defined as a foreign agent, the mobile IP network designed for use with an IPv6 does not have the above mentioned function entity (or concept). Therefore, when the IPv6 is installed in the system configured based on the foreign agent, an amendment is to be made to the current specification or design.  
       SUMMARY OF THE INVENTION  
       [0019] The present invention aims at providing a system and a method for efficiently distributing to a corresponding communications appliance the information for use in providing a communications service for a mobile node in a mobile IP network. Especially, in the mobile IP network for supporting the IPv6.  
       [0020] The communications service providing system according to the present invention includes an authentication server for authenticating a mobile node, and a database storing service control information for use in providing a communications service requested by the mobile node, and provides the communications service to the mobile node according to the service control information. The system includes: a first unit, provided in a mobile node, for storing location registration request information in the header of a packet and transmitting it to the authentication server; a second unit, provided in the authentication server, for extracting the service control information corresponding to the mobile node from the database; a third unit, provided in the authentication server, for storing the location registration request information in the header of the packet and transmitting it to the home agent of the mobile node, a fourth unit, provided in the home agent, for registering the location of the mobile node according to the location registration request information, storing the location registration reply information corresponding to the location registration request information in the header of the packet, and returning it to the authentication server; and a fifth unit, provided in the authentication server, for transmitting to the mobile node a packet containing in the head the location registration reply information and the service control information. With the configuration, a packet transmitted or received by the mobile node is controlled according to the service control information.  
       [0021] In this system, within a procedure of registering the location of a mobile node, the service control information about the mobile node is distributed to the mobile node. At this time, the information relating to the location registration of a mobile node is transmitted after being stored in the header of a packet. Therefore, in a network in which the payload of each packet is encrypted, each communications appliance can decode and process the information relating to the location registration of the mobile node.  
       [0022] The communications service providing system according to another aspect of the present invention includes: a first unit, provided in a router device accommodating a mobile node, for storing location registration request information generated by the mobile node in the header of a packet and transmitting it to the authentication server; a second unit, provided in the authentication server, for extracting the service control information corresponding to the mobile node from the database; a third unit, provided in the authentication server, for storing the location registration request information in the header of the packet and transmitting it to the home agent of the mobile node, a fourth unit, provided in the home agent, for registering the location of the mobile node according to the location registration request information, storing the location registration reply information corresponding to the location registration request information in the header of the packet, and returning it to the authentication server; and a fifth unit, provided in the authentication server, for transmitting to the router device a packet containing in the head the location registration reply information and the service control information. With the configuration, a packet transmitted or received by the mobile node is controlled according to the service control information distributed to the router device.  
       [0023] In this system, the service control information about the mobile node is distributed to the router device accommodating the mobile node within the procedure of registering the location of the mobile node. Then, the router device provides a communications service according to the service control information, thereby reducing the load of the mobile node.  
       [0024] The communications service providing system according to a further aspect of the present invention includes: a first unit, provided in an address server, for transmitting an authentication request about a mobile node to the authentication server when it receives an address request from the mobile node; a second unit, provided in the authentication server, for extracting the service control information corresponding to the mobile node from the database when it receives the authentication request, and transmitting an authentication reply corresponding to the authentication request and the service control information to the address server; and a third unit, provided in the address server, for transmitting an address reply corresponding to the address request and the service control information to the mobile node when it receives the authentication reply and the service control information. According to the service control information, a packet transmitted or received by the mobile node is controlled.  
       [0025] With the system, the service control information about the mobile node is distributed to the mobile node in a procedure in which the mobile node obtains an address from the address server.  
       [0026] The communications service providing system according to a further aspect of the present invention includes: a first unit, provided in an address server, for transmitting an authentication request about a mobile node to the authentication server when it receives an address request from the mobile node; a second unit, provided in the authentication server, for extracting the service control information corresponding to the mobile node from the database when it receives the authentication request, and transmitting an authentication reply corresponding to the authentication request and the service control information to the address server; a third unit, provided in a router device accommodating the mobile node, for obtaining the service control information transmitted from the authentication server to the address server; and a fourth unit, provided in the address server, for transmitting an address reply corresponding to the address request to the mobile node when it receives the authentication reply. A packet transmitted and received by the mobile node is controlled according to the service control information.  
       [0027] With the system, the service control information about the mobile node is distributed to the router device accommodating the mobile node in a procedure in which the mobile node obtains the address from the address server. Then, the router device provides a communications service according to the service control information, thereby reducing the load of the mobile node.  
       [0028] The communications service providing system according to a further aspect of the present invention includes: a first unit, provided in an address server, for transmitting a request message corresponding to an address request to a router device accommodating the address server when it receives the address request from a mobile node; a second unit, provided in the router device, for transmitting an authentication request about the mobile node to the authentication server when it receives the request message; a third unit, provided in the authentication server, for extracting service control information corresponding to the mobile node from the database when it receives the authentication request, and transmitting an authentication reply corresponding to the authentication request and the service control information to the address server; a fourth unit, provided in the router device, for obtaining the service control information transmitted from the authentication server to the address server, and transmitting to the address server an reply message corresponding to the request message according to the authentication reply transmitted from the authentication server to the address server; and a fifth unit, provided in the address server, for transmitting to the mobile node an address reply corresponding to the address request when it receives the reply message. A packet transmitted or received by the mobile node is controlled according to the service control information.  
       [0029] In this system, the address server does not process the authentication request about the mobile node or a corresponding authentication reply, thereby configuring a simple address server, and reducing the load of the address server.  
       [0030] The communications service providing system according to a further aspect of the present invention includes: a first unit, provided in a router device accommodating a mobile node, for transmitting to an authentication server an authentication request about the mobile node when it receives an address request from the mobile node; a second unit, provided in the authentication server, for extracting service control information corresponding to the mobile node from a database when it receives the authentication request, and transmitting to the router device an authentication reply corresponding to the authentication request and the service control information; and a third unit, provided in the router device, for transmitting to the mobile node an address reply corresponding to the address request and the service control information when it receives the authentication reply and the service control information. A packet transmitted and received by the mobile node is controlled according to the service control information.  
       [0031] In the system, the router device has the function of an address server, and the mobile node inquires an address of the router device. Therefore, a simple system configuration is realized, and the amount of information transmitted and received through a network is reduced.  
       [0032] The communications service providing system according to a further aspect of the present invention includes: a first unit, provided in a router device accommodating a mobile node, for transmitting to an authentication server an authentication request about the mobile node when it receives an address request from the mobile node; a second unit, provided in the authentication server, for extracting service control information corresponding to the mobile node from a database when it receives the authentication request, and transmitting to the router device an authentication reply corresponding to the authentication request and the service control information; and a third unit, provided in the router device, for obtaining the service control information and transmitting to the mobile node an address reply corresponding to the address request when it receives the authentication reply and the service control information. A packet transmitted and received by the mobile node is controlled according to the service control information.  
       [0033] In the system, the router device accommodating the mobile node provides a communications service according to the service control information, thereby reducing the load of the mobile node.  
       [0034] The address server device according to the present invention is provided for the communications service providing system which includes an authentication server authenticating the mobile node and a database storing service control information for use in providing a communications service requested by a mobile node, and provides a communications service for the mobile node. The address server device includes: a first unit for transmitting an authentication request about the mobile node to the authentication server when it receives an address request from the mobile node; and a second unit for transmitting to the mobile node an address reply corresponding to the address request and the service control information when it receives from the authentication server an authentication reply corresponding to the authentication request and the service control information corresponding to the mobile node extracted from the database.  
       [0035] According to the address server device, the process of assigning an address to a mobile node and the process of authenticating the mobile node are simultaneously performed.  
       [0036] The router device according to the present invention accommodates a mobile node in the communications service providing system which includes an authentication server authenticating the mobile node and a database storing service control information for use in providing a communications service requested by the mobile node, and provides a communications service for the mobile node. The router device includes: a first unit for transmitting an authentication request about the mobile node to the authentication server when it receives an address request from the mobile node; and a second unit for transmitting to the mobile node an address reply corresponding to the address request and the service control information when it receives from the authentication server an authentication reply corresponding to the authentication request and the service control information corresponding to the mobile node extracted from the database.  
       [0037] According to the router device, the process of assigning an address to a mobile node and the process of authenticating the mobile node are simultaneously performed. In addition, since the router device has the function of an address server, the system configuration is simple, and the amount of information transmitted and received through a network is reduced.  
       [0038] The router device according to another aspect of the present invention includes: a first unit for transmitting an authentication request about the mobile node to the authentication server when it receives an address request from the mobile node; a second unit for transmitting an address reply corresponding to the address request to the mobile node when it receives from the authentication server an authentication reply corresponding to the authentication request and the service control information corresponding to the mobile node extracted from the database; and a third unit for controlling a packet transmitted or received by the mobile node according to the service control information.  
       [0039] According to the router device, the process of assigning an address to a mobile node and the process of authenticating the mobile node are simultaneously performed. In addition, since the router device provides a communications service using the service control information, the load of the mobile node can be reduced. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0040]FIG. 1 shows the configuration of an existing common mobile IP network;  
     [0041]FIG. 2 shows the location registration sequence of the mobile node in the existing system;  
     [0042]FIG. 3 shows the configuration of a packet transmitted in the location registration sequence shown in FIG. 2;  
     [0043]FIG. 4 shows the configuration of a packet processed according to the IPsec;  
     [0044]FIG. 5 shows the configuration of the network of the communications service providing system according to the first embodiment of the present invention;  
     [0045]FIG. 6 shows the configuration of the main devices of the communications service providing system according to the first embodiment;  
     [0046]FIG. 7 shows the configuration of the network of the communications service providing system according to the second embodiment of the present invention;  
     [0047]FIG. 8 shows the configuration of the central devices of the communications service providing system according to the second embodiment;  
     [0048]FIG. 9 shows the packet used in the procedure of registering the location of a mobile node;  
     [0049]FIG. 10 is a block diagram of a mobile node, a proxy foreign agent, a home agent, and a communications node;  
     [0050]FIGS. 11A and 11B show an example of a session transaction held by a mobile node, a proxy foreign agent, and a home agent;  
     [0051]FIGS. 12A, 12B, and  12 C respectively show examples of a visitor list, mobility binding, and binding cache;  
     [0052]FIGS. 13A and 13B show examples of communications node list;  
     [0053]FIG. 14 is a block diagram of an AAAF and an AAAH;  
     [0054]FIG. 15 shows an example of a session transaction held by an AAAF;  
     [0055]FIG. 16 shows an example of a session transaction held by an AAAH;  
     [0056]FIG. 17 shows the information stored in a database (SPDB);  
     [0057]FIG. 18 shows a practical example of band control;  
     [0058]FIG. 19 shows an example of a service profile stored in service profile cache;  
     [0059]FIG. 20 is a flowchart ( 1 ) of the operations performed when a packet is received;  
     [0060]FIG. 21 is a flowchart ( 2 ) of the operations performed when a packet is received;  
     [0061]FIG. 22 is a flowchart of the operations of a mobile node according to the first embodiment of the present invention;  
     [0062]FIG. 23 is a flowchart of the process of registering a communications node in a communications node list in a mobile node;  
     [0063]FIG. 24 is a flowchart of the operations of a mobile node according to the second embodiment of the present invention;  
     [0064]FIG. 25 is a flowchart of the operations of a proxy foreign agent;  
     [0065]FIG. 26 is a flowchart of the process of registering a communications node in a communications node list in a proxy foreign agent;  
     [0066]FIG. 27 is a flowchart of the operations of a home agent;  
     [0067]FIG. 28 is a flowchart of the process of registering a communications node in a communications node list in a home agent;  
     [0068]FIG. 29 is a flowchart of the operations of an AAAF;  
     [0069]FIG. 30 is a flowchart of the operations of an AAAH;  
     [0070]FIG. 31 is a flowchart of the operations of an communications node;  
     [0071]FIG. 32 shows the location registration sequence in the system according to the first embodiment of the present invention;  
     [0072]FIG. 33 shows the location registration sequence in the system according to the second embodiment of the present invention;  
     [0073]FIG. 34 shows the sequence of setting binding cache in a communications node from which a packet is transmitted to a mobile node (when a communications node list is generated in a home agent);  
     [0074]FIG. 35 shows the sequence of setting binding cache in a communications node from which a packet is transmitted to a mobile node (when a communications node list is generated in a mobile node);  
     [0075]FIG. 36 shows the sequence of setting binding cache in a communications node from which a packet is transmitted to a mobile node (when a communications node list is generated in a proxy foreign agent);  
     [0076]FIG. 37 shows the configuration of the network of the communications service providing system according to the third and fourth embodiments of the present invention;  
     [0077]FIG. 38 shows the configuration of the main devices of the communications service providing system according to the third embodiment of the present invention;  
     [0078]FIG. 39 shows the configuration of the main devices of the communications service providing system according to the fourth embodiment of the present invention;  
     [0079]FIG. 40 is a flowchart of the operations of the mobile node according to the third embodiment of the present invention;  
     [0080]FIG. 41 is a flowchart of the operations of the mobile node according to the fourth embodiment of the present invention;  
     [0081]FIG. 42 is a flowchart ( 1 ) of the operations of the proxy foreign agent;  
     [0082]FIG. 43 is a flowchart ( 2 ) of the operations of the proxy foreign agent;  
     [0083]FIG. 44 is a flowchart of the operations of the DHCP server (when an FDR or an FDA is not used);  
     [0084]FIG. 45 is a flowchart of the operations of the DHCP server (when an FDR or an FDA is used);  
     [0085]FIG. 46 is a flowchart of the operations of the home agent;  
     [0086]FIG. 47 is a flowchart of the operations of an AAAF;  
     [0087]FIG. 48 is a flowchart of the operations of an AAAH;  
     [0088]FIG. 49 is a flowchart of the operations of the communications node;  
     [0089]FIG. 50 shows the sequence of the DHCP-AAA cooperative operations according to the third embodiment of the present invention;  
     [0090]FIG. 51 shows the sequence of the DHCP-AAA cooperative operations according to the fourth embodiment of the present invention;  
     [0091]FIG. 52 shows the sequence of the DHCP-AAA cooperative operations when an FDR and an FDA are used;  
     [0092]FIG. 53 shows the configuration of the network of the communications service providing system according to the fifth embodiment of the present invention;  
     [0093]FIG. 54 shows the configuration of the main devices of the communications service providing system according to the fifth embodiment of the present invention;  
     [0094]FIG. 55 is a flowchart of the router device according to the fifth embodiment of the present invention;  
     [0095]FIG. 56 shows the sequence of the DHCP-AAA cooperative operations according to the fifth embodiment of the present invention;  
     [0096]FIG. 57 shows the configuration of the network of the communications service providing system according to the sixth embodiment of the present invention;  
     [0097]FIG. 58 shows the configuration of the main devices of the communications service providing system according to the sixth embodiment of the present invention;  
     [0098]FIG. 59 is a flowchart ( 1 ) of the operations of the proxy foreign agent according to the sixth embodiment of the present invention;  
     [0099]FIG. 60 is a flowchart ( 2 ) of the operations of the proxy foreign agent according to the sixth embodiment of the present invention;  
     [0100]FIG. 61 shows the sequence of the DHCP-AAA cooperative operations according to the sixth embodiment of the present invention;  
     [0101]FIG. 62 shows the format of the IPv6 packet;  
     [0102]FIG. 63 shows the format of the standard header of the IPv6 packet;  
     [0103]FIGS. 64A through 64E show the information stored in the option header of the IPv6 packet;  
     [0104]FIGS. 65A and 65B show the format of the IPsec header;  
     [0105]FIG. 66 shows the format of the AAA option;  
     [0106]FIGS. 67A through 67C show the information stored in the sub-option area of the AAA option shown in FIG. 66;  
     [0107]FIGS. 68A and 68B show an example of a service profile option;  
     [0108]FIG. 69 shows the method of encapsulating the IPv6 packet;  
     [0109]FIG. 70 shows the format of the IPv6 packet storing a DHCP message;  
     [0110]FIGS. 71A through 71C show the format of the information relating to a DHCP request;  
     [0111]FIGS. 72A through 72C show the format of the information relating to a DHCP reply;  
     [0112]FIG. 73 shows the format of the IPv6 storing the information relating to DIAMETER;  
     [0113]FIG. 74 shows the format of the UDP header  
     [0114]FIG. 75 shows the format of the DIAMETER common header;  
     [0115]FIGS. 76A through 76C show the format of the AVP group;  
     [0116]FIGS. 77A through 77D show the format of the DIAMETER message used in the system according to the third and fourth embodiments of the present invention; and  
     [0117]FIGS. 78A through 78C show the format of the service profile cache AVP. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0118] The embodiments of the present invention are described below by referring to the attached drawings.  
     [0119] 1. Outline of the first and second embodiments  
     [0120]FIG. 5 shows the configuration of the network of the communications service providing system according to the first embodiment of the present invention. In the network according to the first embodiment shown in FIG. 5, the home network  1  managed by the service provider of the mobile node (MN) and the foreign networks  2  through  4  managed by other service providers are interconnected through the IP network  5 . The IP network  5  supports the IPv6.  
     [0121] The mobile IP protocol used in the system according to the present embodiment is based on the IPv6. The protocol is hereinafter referred to as a “mobile IPv6”, or a “MIPv6”. The specification of the mobile IPv6 can be obtained from, for example, &lt;draft-ietf-mobileip-ipv6-10.txt&gt; as an Internet draft by the IETF (Internet engineering task force).  
     [0122] The home network  1  is provided with a home agent (HA)  21  and an AAAH (authentication, authorization, and accounting home) server  22 . The home agent  21  is a function entity defined by the RFC2002 and the MIPv6, and can be realized by the router device. In addition, the home agent  21  holds and manages the home address assigned for the mobile node, and manages the location of the mobile node. On the other hand, the AAAH server  22  is a server device (authentication server) for performing the authenticating, authorizing, and accounting processes on a mobile node. The AAAH is the name used in the IETF.  
     [0123] The home network  1  is provided with one or more AAAHs, and one or more home agents. Furthermore, a plurality of home agents can be connected to each AAAH.  
     [0124] A database (SPDB)  23  stores necessary service control information (which can be referred to as a “service profile”) for use in providing a communications service for each mobile node. The database  23  can be accessed only by the AAAH server  22 . The AAAH server  22  and the home agent  21  are provided with a service profile cache (SPC). The service profile cache temporarily stores a service profile read from the database  23 . The retrieval protocol of the database  23  is not specifically limited, but can be, for example, an LDAP (light weight directory access protocol).  
     [0125] Furthermore, a base station  24  is connected to each home agent  21 . The base station  24  is provided with a radio interface, and establishes a radio transmission path to a terminal device (including a mobile node). A radio access system can be, for example, MC-CDMA (multicarrier-code division multiple access), DS-CDMA (direct spread-code division multiple access), etc.  
     [0126] The foreign networks  2  through  4  are provided with router devices  31  ( 31 - 1 ,  31 - 2 ), AAAF (authentication, authorization, and accounting foreign) servers  32  ( 32 - 1 ,  32 - 2 ), and base stations  33  ( 33 - 1 ,  33 - 2 ). Each router device  31  transfers a packet according to the destination address, etc. set in the header of each packet. Each router device  31  provides the function of a home agent for the mobile node in which the home address is held and managed by the router device. For example, the router device  31 - 1  operates as a home agent of a mobile node in contract with the foreign network  2 .  
     [0127] As the AAAH server  22 , the AAAF server  32  is a server device for performing the authenticating, authorizing, and accounting processes on a mobile node. However, each AAA device (including an AAAH and an AAAF) performs the authenticating, authorizing, and accounting processes only on the mobile node to be managed. Therefore, when each AAA device receives an access request from a mobile node which is not to be managed by the AAA device, it requests an AAA device which manages the mobile node to perform the process according to the request. Then, the requested AAA device processes the access request. At this time, the requesting AAA device is an AAAF for the mobile node, and the requested AAA device is an AAAH for the mobile node.  
     [0128] A mobile node (mobile terminal device)  41  is accommodated in the home agent  21  or any router device  31 , and communicates with other terminal devices. In this example, the terminal device communicating with the mobile node  41  is referred to as a communications node (CN)  42 . When the mobile node  41  establishes communications through a radio transmission path, it is accommodated by the router device  31  through the base station  33 . In this case, the radio access system can be, for example, MC-CDMA, DS-CDMA, etc. The mobile node  41  can be connected to a radio LAN, or to the router device  31  through metal cable or optical fiber.  
     [0129] Thus, in the network according to the first embodiment, there is no foreign agent unlike the existing network shown in FIG. 1.  
     [0130]FIG. 6 shows the configuration of the main devices of the communications service providing system according to the first embodiment of the present invention. In this system, it is assumed that DIAMETER is used as a protocol for performing the authenticating, authorizing, and accounting processes on a mobile node. The prescriptions of the DIAMETER protocol as a draft by the IETF can be obtained from, for example, &lt;draft-calhoun-diameter-12.txt&gt; and &lt;draft-calhoun-diameter-mobileip-07.txt&gt;.  
     [0131] In the communications service providing system according to the first embodiment of the present invention, each of the home agent  21 , the AAAH server  22 , the AAAF server  32 , the mobile node  41 , and the communications node  42  is provided with a packet control unit, a protocol control unit, a service management unit or a service control unit, and service profile cache. The router device  31  is provided with a packet control unit. Each of the home agent  21 , the mobile node  41 , and the communications node  42  is provided with a transfer control unit. The configurations and the operations of the packet control unit, the protocol control unit, the service management unit or the service control unit, the service profile cache, and the transfer control unit are described later.  
     [0132] The router device  31  can function as a home agent for a mobile node in contract with the foreign network  2  or  3 . In this case, the router device  31  is provided with the protocol control unit, the service control unit, the transfer control unit, the service profile cache (SPC), the function of the DIAMETER client described later, and the function of the mobile IP server described later.  
     [0133] Each of the mobile node  41  and the communications node  42  is provided with a mobile IP client function (MCF) for requesting another communications appliance to perform a process prescribed by the mobile IP. On the other hand, the home agent  21  is provided with a mobile IP server function (MSF) for accepting a request relating to the process prescribed by the mobile IP. Each of the mobile node  41  and the home agent  21  is provided with a DIAMETER client function (DCF) for requesting another communications appliance to perform the process prescribed by the DIAMETER protocol. On the other hand, each of the AAAH server  22  and the AAAF server  32  is provided with a DIAMETER server function (DSF) for accepting a request relating to the process prescribed by the DIAMETER protocol. Since these functions are known technologies, the detailed explanation is omitted here.  
     [0134]FIG. 7 shows the configuration of the network of the communications service providing system according to the second embodiment of the present invention. FIG. 8 shows the configuration of the main devices of the according to the second embodiment of the present invention. In the system according to the second embodiment, the communications appliance for accommodating a mobile node  51  functions as a proxy foreign agent (proxy FA)  52 . The proxy foreign agent  52  is a communications appliance practically having the equivalent function of the foreign agent prescribed in the mobile IPv4, and can be realized by adding that function to the router device. That is, the proxy foreign agent  52  comprises not only a packet control unit, but also a protocol control unit, a service control unit, a transfer control unit, service profile cache (SPC) to realize the above mentioned function. The protocol control unit of the proxy foreign agent  52  comprises a mobile IP server function (MSF) and a DIAMETER client function (DCF).  
     [0135] Unlike the mobile node  41 , the mobile node  51  does not comprise a service control unit, a transfer control unit, or service profile cache (SPC). In addition, in the system according to the second embodiment, a DIAMETER protocol is supported by the proxy foreign agent  52 . As a result, the protocol control unit of the mobile node  51  is not necessarily provided with the DIAMETER client function (DCF).  
     [0136] In the system according to the first or second embodiment of the present invention, the location of a mobile node is registered in the following procedure.  
     [0137] (1) The router device  31  or the mobile node  51  announce an advertisement message.  
     [0138] (2) Upon receipt of the advertisement message, the mobile nodes  41  and  51  transmits a location registration request message to the router device  31  or the proxy foreign agent  52 . At this time, the mobile nodes  41  and  51  also transmit an AMR (AA-mobile-node-request) message.  
     [0139] (3) Upon receipt of a location registration message, the router device  31  or the proxy foreign agent  52  transmits the AMR message to the AAAF server  32 .  
     [0140] (4) Upon receipt of the AMR message, the AAAF server  32  transfers it to the AAAH server  22 .  
     [0141] (5) Upon receipt of the AMR message, the AAAH server  22  performs the authenticating, authorizing, and accounting processes on the mobile nodes  41  or  51 , and transmits an HAR (home-agent-MIP-request) message to the home agent  21 .  
     [0142] (6) Upon receipt of the HAR message, the home agent  21  registers the locations of the mobile nodes  41  or  51 , and returns an HAA (home-agent-MIP-answer) message to the AAAH server  22 .  
     [0143] (7) Upon receipt of the HAA message, the AAAH server  22  transmits an AMA (AA-mobile-node-answer) message to the AAAF server  32 .  
     [0144] (8) Upon receipt of the AMA message, the AAAF server  32  transfers it to the router device  31  or the proxy foreign agent  52 .  
     [0145] (9) Upon receipt of the AMA message, the router device  31  or the proxy foreign agent  52  transmits a location registration reply message to the mobiles nodes  41  or  51 . At this time, the router device  31  or the proxy foreign agent  52  can transmit the AMA message to the mobile nodes  41  or  51 .  
     [0146] (10) When the mobile nodes  41  or  51  receives the location registration reply message, the location registration procedure terminates.  
     [0147] In the communications service providing method according to the present invention, the service control information (hereinafter referred to as a “service profile”) corresponding to the mobile nodes  41  and  51  is distributed to a corresponding communications appliance in the above mentioned location registration procedure. Practically, the service profile corresponding to the mobile nodes  41  and  51  is extracted from the database  23  by the AAAH server  22 . The service profile is distributed together with the HAR message to the home agent  21 , and is distributed together with the AMA message to the AAAF server  32 . Furthermore, the service profile is distributed to the mobile node  41  together with the AMA message according to the first embodiment, and is distributed together with the AMA message to the proxy foreign agent  52  according to the second embodiment. At this time, the distributed service profile is stored in service profile cache (SPC).  
     [0148] The above mentioned information (containing various messages, service profiles, etc.) is basically stored in an IPv6 packet and transmitted. Described below is the configuration of a packet transmitted and received in the system according to the first and second embodiments.  
     [0149]FIG. 62 shows the format of an IPv6 packet. An IPv6 packet comprises an IP header and an IP payload. In the IPv6, the IP header comprises a standard header and an option header. In the IP payload, a UDP packet is stored. The specification, etc. of the IPv6 is described in detail in the RFC2469 of the IETF.  
     [0150] In the IPv6, it is necessary to support an IPsec (IP security protocol). The IPsec contains an encryption protocol for encrypting the option header and the payload of the IP packet. It is determined depending on the setting of the C flag in the IP header as to whether or not the option header is to be encrypted.  
     [0151]FIG. 63 shows the format of the standard header of the IPv6 packet. The standard header comprises version information, a traffic class, a flow label, a payload length, a next header, the number of hop restrictions, a source address, and a destination address. Since the format of the standard header is well known, the detailed explanation is omitted here.  
     [0152]FIGS. 64A through 64E show the information stored in the option header of the IPv6 packet. FIG. 64A shows the format of an end point option. The end point option stores the information referred to by a terminal (including a mobile node, a home agent, a communications node).  
     [0153]FIG. 64B shows the format of a relay point option. The relay point option stores the information referred to by a relay device (including an AAA server, a home agent, a router device). The above mentioned C flag is provided in, for example, the option area of the relay point option.  
     [0154]FIG. 64C shows the format of a binding update option. The binding update option stores a binding update message generated by a mobile node. An A-bit indicates whether or not the device which has received the binding update message has to return the binding acknowledge message. An H-bit indicates whether or not home registration is to be performed on a mobile node. The mobile node sets the H-bit depending on whether or not the source of the received advertisement message matches the source of the previously received advertisement message in the environment in which, for example, a router device or a proxy foreign agent periodically transmits an advertisement message. At this time, when the sources of the above mentioned two messages match each other, the mobile node is assumed to have been registered in the home agent  21 . If they do not match, a current location of the mobile node has not been registered in the home agent  21 .  
     [0155]FIG. 64D shows the format of a binding acknowledge option. The binding acknowledge option stores a binding acknowledge message generated by the device which has received the binding update message.  
     [0156] The binding update option and the binding acknowledge option can be stored in, for example, the option area of the end point option shown in FIG. 64A.  
     [0157]FIG. 64E shows the format of a home address option. The home address option stores the home address of a mobile node.  
     [0158]FIGS. 65A and 65B show the format of the IPsec header. In the system according to the present embodiment, an authentication header (AH: authentication header) protocol or an ESP (encapsulating security payload) protocol is used to realize the IPsec.  
     [0159]FIG. 65A shows the format of an IP authentication header. The IP authentication header contains a next header, a payload length, an SPI (security parameters Index), and authentication data. FIG. 65B shows the format of an ESP header. The ESP header contains a next header, a payload length, an SPI, and encrypted data. These IPsec headers are stored in the option header of the IPv6 packet. The specification of the authentication header and the ESP is described in detail respectively in the RFC 2402 and the RFC 2406 of the IETF.  
     [0160]FIG. 66 shows the format of an AAA option. The AAA option contains a command code identifying the DIAMETER message. Practically, the command code identifies the AMR message, the AMA message, the HAR message, and the HAA message. The AAA option is stored in the option header of the IPv6 packet. Practically, the AAA option can be stored in, for example, the option area of the relay point option shown in FIG. 64B. In addition, the AAA option can also be stored in the option area of the end point option shown in FIG. 64A.  
     [0161]FIGS. 67A through 67C show the information stored in the sub-option area of the AAA option shown in FIG. 66. FIG. 67A shows an example of an MN-NAI extension sub-option. The MN-NAI extension sub-option stores the NAI (network access identifier) of a mobile node. Each mobile node is uniquely identified by the NAI.  
     [0162]FIG. 67B shows an example of an MN-AAA authentication extension sub-option. The MN-AAA authentication extension sub-option stores an SPI and an authentication data for authenticating a mobile node.  
     [0163]FIG. 67C shows an example of a session ID option. The session ID option stores a session ID. The session ID is identification information for correlating a plurality of messages used in the location registration sequence of each mobile node.  
     [0164]FIG. 68A shows the format of a service profile option. The service profile option contains a vendor ID, a session ID, a service profile group, etc. The service profile option is stored in the option header of an IPv6 packet. Practically, the service profile option can be stored in, for example, the option area of the relay point option shown in FIG. 64B or the option area of the end point option shown in FIG. 64A.  
     [0165]FIG. 68B shows an example of a service profile group stored in the service profile option shown in FIG. 68A. The service profile group comprises one or more service profiles for providing communications services for corresponding mobile node. The service profile of corresponding mobile node is extracted from the database (SPDB)  23  shown in FIGS. 5 through 8.  
     [0166]FIG. 69 shows the method of encapsulating an IPv6 packet. The encapsulation of a packet (tunnel transfer) is performed when an original packet is transferred to a destination other than a final destination of the original packet. In this case, a tunnel packet can be generated by assigning a header in which the other destination is set in the original packet. That is, the original packet is stored in the payload of the tunnel packet. The method of encapsulating the IPv6 packet is described in detail in the RFC 2473 of the IETF.  
     [0167]FIG. 9 shows a packet used in the location registration procedure of a mobile node. In this example, the packet according to the second embodiment in FIGS. 7 and 8 is shown.  
     [0168] The location registration is started by the mobile node  51  issuing a location registration request. Since the location registration request is practically a message requesting to update a mobility binding table provided in the home agent  21 , the location registration request is hereinafter referred to as “binding update”. A mobility binding table is a table for use by the home agent  21  in managing the location of the mobile node  51 .  
     [0169] The binding update request transmitted by the mobile node  51  and the related information are stored in the option header of the IPv6 packet. Practically, the option header of the IPv6 packet transmitted from the mobile node  51  is assigned the relay point option shown in FIG. 64B, the AAA option shown in FIG. 66, the end point option shown in FIG. 64A, the binding update option shown in FIG. 64C, and the authentication header/ESP option shown in FIG. 65A or  65 B. In this example, the AMR message is set in the AAA option. The sub-option of the AAA option stores the MN-AAA authentication extension sub-option shown in FIG. 67B. The IPv6 packet is transmitted to the proxy foreign agent  52 .  
     [0170] Upon receipt of the IPv6 packet from the mobile node  51 , the proxy foreign agent  52  encapsulates and transmits it to the AAAF server  32 . At this time, a session ID option is set in the AAA option stored in the option header of the IPv6 packet.  
     [0171] Upon receipt of the IPv6 packet from the proxy foreign agent  52 , the AAAF server  32  transfers it to the AAAH server  22 . Then, the AAAH server  22  decapsulates the received IPv6 packet, and transfers it to the home agent  21 . At this time, instead of the AMR message the HAR message is set in the AAA option of the IPv6 packet. In addition, the service profile option shown in FIGS. 68A and 68B is added to the option header of the IPv6 packet.  
     [0172] Upon receipt of the IPv6 packet, the home agent  21  obtains necessary information from the binding update option in the option header, updates the mobility binding table, and obtains the service profile of the of the mobile node  51  from the service profile option. Then, the binding acknowledge message is returned from the home agent  21  to the mobile node  51 , but the detailed explanation of the procedure is omitted here. The home agent  21  notifies the communications node  42  of the binding update message and the service profile of the mobile node  51  as necessary.  
     [0173] The configuration of a packet is basically the same as in the first embodiment. However, in the first embodiment, the mobile node  41  assigns a session ID option.  
     [0174] Thus, the necessary information in the location registration procedure (including the procedure of authenticating a mobile node) of the mobile nodes  41  and  51 , and the service profile of the mobile node are stored in the option header of the IPv6 packet, and is then transferred. Generally, the IPv6 packet is encrypted by the IPsec. However, in the IPv6, it can be selected whether or not the option header of the IPv6 packet is to be encrypted. Practically, for example, it can be selected whether or not the option header is to be encrypted using the C flag set in the above mentioned relay point option. In the system according to the first and second embodiment, the option header is not encrypted. Therefore, the proxy foreign agent  52 , the AAAF server  32 , and the AAAH server  22  can obtain necessary information (especially DIAMETER message, etc.) for the location registration of the mobile nodes  41  and  51  from the IPv6 packet transferred in the location registration procedure.  
     [0175] 2. Configuration of each device  
     [0176] 2.1 Mobile Node, Proxy Foreign Agent, Home Agent, and Communication Node  
     [0177]FIG. 10 is a block diagram of the mobile node, the proxy foreign agent, the home agent, and a communications node. The mobile node, the proxy foreign agent, the home agent, and a communications node have basically the same function block. However, the mobile node  51  according to the second embodiment does not have to be provided with a service control unit or a transfer control unit.  
     [0178] A packet control unit  101  has a filtering function, and classifies packets based on the header of each packet into data packets and protocol packets. The packet control unit  101  edits the packets and transmits them according to the instructions from a service control unit  103  and a transfer control unit  104 .  
     [0179] A protocol control unit  102  performs a process based on the mobile IP, an AAA protocol (DIAMETER), and a DHCP (dynamic host configuration protocol) The protocol control unit  102  holds a session transaction for managing an AAA session. An example of the session transaction is shown in FIGS. 11A and 11B. FIG. 11A shows an example of the session transaction held by the mobile node  41  or the proxy foreign agent  52 . FIG. 11B shows an example of the session transaction held by the home agent  21 .  
     [0180] The service control unit  103  is provided with service profile cache, and holds a service profile extracted from the database (SPDB)  23 .  
     [0181] The transfer control unit  104  manages the control information relating to packet transfer. A visitor list is held by the proxy foreign agent  52 . As shown in FIG. 12A, the visitor list stores a home address (originally assigned IP address) of a mobile node, a link layer address (for example, a MAC address) of a mobile node, an address of the home agent managing a mobile node, information for authentication of a mobile node, etc.  
     [0182] The mobility binding is held by the home agent  21 . As shown in FIG. 12B, the mobility binding stores a home address of a mobile node, an address currently assigned to a mobile node when the mobile node exits its home network, information for authentication of a mobile node, etc.  
     [0183] The binding cache is held by the communications node  42 . The configuration of the binding cache is similar to that of the mobility binding. However, the binding cache stores the information for indicating a method of encapsulating a packet as shown in FIG. 12C.  
     [0184] A communications node list is held by a proxy foreign agent, a home agent, or a mobile node. The address of a communications node to which a binding update message has ever been transmitted is registered in the communications node list as shown in FIG. 13A. The address of the communications node registered in the communications node list is deleted after a period prescribed by “lifetime” has passed. In addition, as shown in FIG. 13B, the address of a communications node to which no binding update message is to be transmitted can be registered.  
     [0185] The routing table stores information for indicating the destination of a transferred packet although it is not shown in the attached drawings.  
     [0186] Described below are the basic operations of a mobile node, a proxy foreign agent, a home agent, and a communications node shown in FIG. 10. The operations performed when the devices receive a packet are described below.  
     [0187] (1) The packet control unit  101  extracts IP header information from a received packet.  
     [0188] (2) The packet control unit  101  checks whether the packet is a protocol packet or a data packet according to the destination address of the received packet, the port number, IPv6 option header information, etc.  
     [0189] Case 1: When a received packet is a protocol packet,  
     [0190] (3) The packet control unit  101  passes control to the protocol control unit  102 . The protocol control unit  102  detects what process is to be performed in the mobile IP, the DIAMETER, the DHCP, the ICMP, and DIAMETER-IPv6 option.  
     [0191] (4) When a service profile is distributed by the DIAMETER-IPv6 or the DIAMETER, the service control unit  103  stores the service profile in the service profile cache.  
     [0192] (5) The protocol control unit  102  updates the transfer control unit  104  according to the message set in the received packet.  
     [0193] (6) The packet control unit  101  generates and transmits a message corresponding to the received message as necessary according to the instruction from the transfer control unit  104 .  
     [0194] Case 2: When a received packet is a data packet,  
     [0195] (7) The packet control unit  101  notifies the service control unit  103  of the header information about a received packet.  
     [0196] (8) The service control unit  103  retrieves a service profile corresponding to the notified header information, and notifies the packet control unit  101  of the routing information/packet editing information according to the service profile.  
     [0197] (9) The transfer control unit  104  issues an instruction to the packet control unit  101  by referring to the visitor list, mobility binding, binding cache, a CN list, or a routing table based on the above mentioned service profile.  
     [0198] (10) The packet control unit  101  edits and transmits a packet according to an instruction from the service control unit  103  and the transfer control unit  104 .  
     [0199] 2.2. AAAF and AAAH  
     [0200]FIG. 14 is a block diagram of an AAAF and an AAAH. The AAAF and the AAAH basically have the same configurations.  
     [0201] A packet control unit  111  extracts necessary information from a received protocol packet, and provides it for a protocol control unit  112 . The packet control unit  111  edits and transmits a packet to a corresponding destination at an instruction from a service management unit  113 .  
     [0202] The protocol control unit  112  supports the DIAMETER and the DIAMETER-IPv6 option. The protocol control unit  112  also holds a session transaction for management of the DIAMETER session.  
     [0203] The service management unit  113  accesses the database (SPDB)  23  according to the header information of the packet received by the packet control unit  111 , and extracts a corresponding service profile therefrom. Then, it holds the service profile in the service profile cache. The service management unit  113  issues a packet edit instruction to the packet control unit  111 . At this time, the service management unit  113  provides a service profile for the packet control unit  111  as necessary. The AAAH can access the database  23 , but the AAAF cannot access the database  23 .  
     [0204]FIG. 15 shows an example of a session transaction held by the AAAF server  32 . The session transaction of the AAAF server  32  includes a session ID, the address of an AAAH, the address of a home agent, the operation state of an AAAF, etc.  
     [0205]FIG. 16 shows an example of a session transaction held by the AAAH server  22 . The session transaction of the AAAH server  22  includes a session ID, the address of a home agent, the address of an AAAF, and the operation of an AAAH, etc.  
     [0206]FIGS. 17A through 17D show the information stored in the database (SPDB)  23  accessed by the AAAH server  22 . FIG. 17A shows the configuration of the database  23 . The database  23  stores a corresponding service profile using the NAI of a mobile node (or a user) as a key. As the information stored for each mobile node, the SPI of a mobile node, the service class in contract between a service provider and a mobile node user, an actually used service class, etc. are registered.  
     [0207] A service class prescribes, as shown in FIG. 17B, an available value added service, QoS (quality of service), the maximum number of profiles, etc. An available value added service can be, for example, as shown in FIGS. 17C and 17D, Diff-Serv (differentiated service), packet filtering, security service, band control, etc. The Diff-Serv is a service for realizing QoS by setting the priority for each packet. The Diff-Serv is prescribed by the RFC 2474 and the RFC 2475 of the IETF. The packet filtering is a service for filtering a packet based on the IP address of each packet, the port number, etc. The security service is realized by, for example, the IPsec. The band control is a service for realizing the QoS by limiting the band available for each mobile node. FIG. 18 shows a practical example of a band control service. In the band control service, an applicable QoS is prescribed for each service class, and the existence of an available band and band compensation is prescribed for each QoS.  
     [0208]FIG. 19 shows an example of a service profile stored in the service profile cache. The service profile cache (SPC) is provided in the AAAH, the AAAF, the home agent, the proxy foreign agent, the mobile node, and the communications node, and stores a service profile extracted from the database  23 . The service profile contains the information for specification of a packet to be filtered, the information for specification of a value added service to be provided, and so on.  
     [0209] 3. Flowchart of the operations of each device according to the first or second embodiment  
     [0210] 3.1 Common process  
     [0211]FIGS. 20 and 21 are flowcharts of the operations performed when each device (a mobile node, a proxy foreign agent, an AAAF, an AAAH, a home agent, a communications node) receives a packet.  
     [0212] Upon receipt of a packet, each device checks whether or not the packet is an IPv6 tunnel packet. It is detected whether or not a packet is an IPv6 tunnel packet according to the header information of the packet. If a received packet is an IPv6 tunnel packet, then control is passed to step S 2 . Otherwise, control is passed to step S 6 .  
     [0213] In step S 2 , it is checked whether or not a received packet is addressed to this corresponding apparatus. That is, it is checked whether or not the destination of the received packet is the device which has received the packet. It can be detected based on the destination address stored in the header of the received packet. If the received packet is addressed to this corresponding apparatus, then control is passed to step S 3 . Otherwise, control is passed to step S 12 . If the source of the received packet is a communications node in step S 12 , then the communications node is registered in the communications node list. This process is performed only by the proxy foreign agent  52 .  
     [0214] When the source of the received packet is a communications node in step S 3 , the communications node is registered in the communications node list. This process is performed only by the mobile node  41  according to the first embodiment of the present invention. In step S 4 , the IPv6 option header of the received packet is analyzed to perform a corresponding process. Steps S 3  and S 4  are described later in detail.  
     [0215] In step S 5 , the IPv6 tunnel packet is decapsulated. In step S 6 , it is checked whether or not the packet obtained in the decapsulating process is addressed to this corresponding apparatus. If the packet obtained in the decapsulating process is addressed to this corresponding apparatus, control is passed to step S 21 . Otherwise, control is passed to step S 7 .  
     [0216] If the source of the received packet is a communications node, the communications node is registered in the communications node list. This process is performed only by the home agent  21 .  
     [0217] In step S 8 , it is checked whether or not the relay point option shown in FIG. 64B is set in the option header of the received packet. If the relay point option is set, the type of message stored in the “option” in the relay point option is detected in steps S 9  and S 10 . Practically, for example, the type of message is detected by referring to the command code of the AAA option shown in FIG. 66. Then, in step S 11 , another predetermined process (relaying process, etc.) is performed as necessary.  
     [0218] In step S 21 , the type of “Next Header” is checked. That is, the header information to be referred to is specified. If the “IPv6 option header” is referred to, control is passed to step S 22  to perform the process relating to the option header shown in FIGS. 64 through 68. If the “UDP header” is referred to, control is passed to step S 31 . When an area other than the “IPv6 option header” or the “UDP header” is referred to, the other process is performed in step S 41 . The other process refers to, for example, a process relating to the ICMP (Internet control message protocol).  
     [0219] In step S 22 , it is checked whether of not the IPsec is being used. If the IPsec is being used, the decoding process and the authenticating process relating to the IPsec are performed in steps S 23  and S 24 . At this time, if the result of the decoding or authenticating process is accepted, it is checked in step S 25  whether or not the end point option shown in FIG. 64A is set in the option header of the received packet. If the end point option is set, the option area in the end point option is checked in steps S 26  and S 27  to detect the type of message. As the type of message, the binding update message, the binding acknowledge message, the binding request message, etc. are contained. The processes in steps S 26  and S 27  are performed by the mobile node, the home agent, or the communications node. On the other hand, if the end point option is not set, then the process relating to a corresponding option is performed in step S 28 .  
     [0220] In step S 31 , a specified protocol is recognized by checking the UDP port number. If the DIAMETER is specified, then the type of message is detected in step S 32 . If the DHCP is specified, then it is determined in step S 33  which is specified, a DHCP request or a DHCP reply. The process in step S 33  is performed by a mobile node or a DHCP server. If a protocol other than DIAMETER or DHCP is specified, then a corresponding process is performed in step S 34 .  
     [0221] 3.2 Mobile node  
     [0222]FIG. 22 is a flowchart of the operation of the mobile node  41  according to the first embodiment of the present invention. The flowchart shows the operation performed after the mobile node  41  receives a packet.  
     [0223] In step S 51 , the type of the received packet is checked. If an IPv6 packet is received, then the processes in and after step S 52  are performed. When an IPv6 tunnel packet is received, a binding update message is transmitted to the communications node  42  in step S 61 . If a packet other than an IPv6 packet or an IPv6 tunnel packet is received, a corresponding process is performed in step S 62 .  
     [0224] In step S 52 , the type of message stored in the received packet is checked. The type of message is detected by referring to the end point option shown in FIG. 64A in the option header. When an ICMP router advertisement message is received, the processes in and after step S 53  are performed. When a binding request message is received, the process in step S 61  is performed. When a binding update message is received, the processes in and after step S 59  are performed.  
     [0225] In step S 53 , it is checked whether or not the source address of a received advertisement message has already been registered in an agent list. In this example, an agent list refers to the memory for holding the source address of the message in a case where a router advertisement message periodically broadcast by each router device is received. An example of no registration of a source address of a received advertisement message in the agent list can be the case in which power source has been supplied to the mobile node, or the mobile node has moved from the communications area of a router to the communications area of another router.  
     [0226] When the source device of the advertisement message is not registered in the above mentioned agent list, it is checked in step S 54  whether or not the mobile node is provided with a communications node list. In the communications node list, a communications node to which a binding update message is to be transmitted is registered as shown in FIG. 13A.  
     [0227] When a mobile node is provided with a communications node list, a service profile is added in the option header of the IPv6 packet. The service profile is stored in the service profile option shown in FIG. 68A. Then, in step S 56 , the binding update option shown in FIG. 64C is set in the block diagram option header. Thus, the service profile and the binding update message are stored in the option header of the IPv6 packet. The IPv6 packet is transmitted to each communications node registered in the communications node list.  
     [0228] In step S 57 , an AAA option is added to the option header. The AAA option is shown in FIG. 66, and an AMR message is set in the AAA option in this example. In the sub-option area of the AAA option, the MN-NAI extension sub-option, the MN-AAA authentication extension sub-option, and the session ID sub-option shown in FIGS. 67A through 67C are stored. Then, in step S 58 , the binding update message is stored in the above mentioned option header. Thus, the AMR message and the binding update message are stored in the option header of the IPv6 packet. The IPv6 packet is transmitted to the home agent  21 .  
     [0229] In step S 59 , it is checked whether or not an AAA option is set in the option header of the IPv6 packet containing the binding acknowledge message. If the AAA option is set, a service profile stored in the option header is obtained in step S 60 . The service profile is stored in the service profile cache.  
     [0230] Thus, upon receipt of the router advertisement message, the mobile node  41  according to the first embodiment transmits the AMR message and the binding update message to the home agent  21 . At this time, if a communications node list is provided, the mobile node  41  can transmit the service profile and the binding update message to one or more communications nodes registered in the list. Furthermore, upon receipt of the IPv6 tunnel packet, the mobile node  41  transmits the binding update message to the communications node which is the source of the packet. If the mobile node  41  receives the service profile together with the binding acknowledge message, then it stores the service profile in its own service profile cache.  
     [0231]FIG. 23 is a flowchart of the process of registering a communications node in the communications node list in the mobile node  41 .  
     [0232] In step S 71 , it is checked whether or not a received packet is an IPv6 tunnel packet transmitted from the home agent  21 . If the packet is the IPv6 packet transmitted from the home agent  21 , then the source IP address of the original packet stored in the tunnel packet is checked in step S 72 .  
     [0233] In step S 73 , it is checked whether or not the IP address detected in step S 72  has been registered in the communications node list. In step S 74 , it is checked whether or not the IP address detected in step S 72  has been registered as the address of the communications node to which the binding update message is not to be transmitted. If the IP address has not been registered in the communications node list, and has not been registered as the address of the communications node to which the binding update message is not to be transmitted, then the IP address is registered in the communications node list in step S 75 .  
     [0234] Thus, upon receipt of a packet from the communications node not registered in the communications node list, the mobile node  41  registers the IP address of the communications node in the communications node list.  
     [0235]FIG. 24 is a flowchart of the operations of the mobile node  51  according to the second embodiment of the present invention. The processes in this flowchart are the operations performed after the mobile node  51  receives a packet.  
     [0236] The operations of the mobile node  51  are basically the same as those of the mobile node  41  shown in FIG. 22. However, the mobile node  51  requests the communications node  42  to perform a part of the functions of the mobile node  41 . Therefore, the mobile node  51  does not perform the processes in steps S 54  through S 56  shown in  22 . Furthermore, the mobile node  51  is not provided with a service profile cache. Therefore, the mobile node  51  does not perform the processes in steps S 59  and S 60  shown in FIG. 22.  
     [0237] In addition, the mobile node  51  according to the second embodiment is not provided with a communications node list. Therefore, the mobile node  51  does not perform the processes in the flowchart shown in FIG. 23.  
     [0238] 3.3 Proxy foreign agent  
     [0239] The proxy foreign agent  52  is a function entity provided in the system according to the second embodiment, and is provided with a part of the functions of the mobile node  41  in the first embodiment.  
     [0240]FIG. 25 is a flowchart of the operations of a proxy foreign agent. The flowchart shows the operations performed after the proxy foreign agent  52  receives a packet.  
     [0241] In step S 81 , the type of message stored in the option header of the received packet is checked. If a binding update message is stored in the received packet, the processes in and after step S 82  are performed If the received packet stores an AMA message, the process in and after step S 101  are performed. If another message is stored, the process corresponding to the message is performed.  
     [0242] In step S 82 , a session transaction is retrieved using the NAI identifying the source of the binding update message. The session transaction managed by the proxy foreign agent  52  is shown in FIG. 11A. If no session transaction corresponding to the NAI is detected, then a session transaction corresponding to the NAI is newly generated in step S 83 .  
     [0243] In step S 84 , it is checked whether or not a home registration bit is set in the option header of the received packet. The home registration bit is provided in the binding update option shown in FIG. 64C. When the home registration bit is set, it is checked in step S 85  whether or not an AAA option is set in the option header. Then, in step S 86 , the remainder of the lifetime of the corresponding session transaction is checked. If an AAA option is set in the option header, and the remainder of the lifetime of the session transaction is 0, then the received binding update message is transmitted to the AAAF server  32  in step S 87 . At this time, the message is stored in the IPv6 tunnel pack, and is transferred. In addition, the MN-AAA authentication extension sub-option, etc. is set in the AAA option. If no AAA option is set in the option header, or if the lifetime of the session transaction still remains, then the binding update message is transmitted to the home agent  21  in step S 88 .  
     [0244] In step S 89 , it is checked whether or not the destination of the binding update message has been registered in the communications node list. If the destination has been registered in the communications node list, the service profile option shown in FIG. 68A is added to the relay point option of the option header in step S 90 . The service profile option stores the service profile of the mobile node  51 . In step S 91 , the packet storing the binding update message is transferred to the communications node. That is, if the destination of the binding update message has been registered in the communications node list, then the binding update message and the service profile of the mobile node are transferred to one or more communications nodes registered in the list. If it has not been registered, then the binding update message is transferred, but the service profile of the mobile node is not transferred.  
     [0245] In step S 101 , it is checked whether or not the service profile option is stored in option header of the IPv6 packet storing the AMA message. If the service profile option is stored, then the service profile stored in the service profile option is obtained in step S 102 . The obtained service profile is stored in the service profile cache provided in the proxy foreign agent  52 . In step S 103 , the packet storing the AMA message is transferred to the mobile node.  
     [0246] As described above, upon receipt of the binding update message, the proxy foreign agent  52  transfers it to the AAAF server  32 , the home agent  21 , or the communications node  42 . At this time, the packet is transferred to the communications node registered in the communications node list after the service profile of the mobile node  51  is added. Upon receipt of the packet storing the AMA message, the proxy foreign agent  52  extracts the service profile of the mobile node  51  from the packet, and then transfers the packet to the mobile node  51 .  
     [0247]FIG. 26 is a flowchart of the process of registering a communications node in the communications node list in the proxy foreign agent  52 .  
     [0248] The registering process in the proxy foreign agent  52  is basically the same as the process in mobile node  41  shown in FIG. 23. However, the proxy foreign agent  52  is not provided with the list in which a communications node to which the binding update message is not to be transmitted is registered. Therefore, the process in step S 74  shown in FIG. 23 is not performed.  
     [0249] 3.4 Home agent  
     [0250] The home agent  21  is a function entity for managing the location of the mobile nodes  41  and  51  using the mobility binding table.  
     [0251]FIG. 27 is a flowchart of the operations of a home agent. The flowchart shows the operations performed after the home agent  21  receives a packet.  
     [0252] In step S 111 , the type of message stored in the option header of the received packet is checked. If a binding update message is stored in the received packet, the processes in and after step S 112  are performed. If the binding update message is not stored, another process is performed in step S 131 .  
     [0253] In step S 112 , it is checked whether or not the AAA option is stored in the option header of the above mentioned packet. If the AAA option is not stored, the processes in steps S 113  through S 117  are performed. In steps S 113  through S 115 , a session transaction is searched for using the NAI of the mobile nodes  41  and  51  as a key. If a corresponding session transaction is not detected, it is generated. Then, in step S 116 , the mobility binding table shown in FIG. 12B is generated. The information to be registered in the mobility binding table is basically extracted from the option header of a received packet. Then, in step S 117 , an IPv6 packet storing the binding acknowledge message in the option header is generated, and is returned to the mobile node  41  or the proxy foreign agent  52 . The binding acknowledge message is stored in the binding acknowledge option shown in FIG. 64E.  
     [0254] When the received packet stores the AAA option, the processes in and after step S 121  are performed. In steps S 121  and S 122 , a session transaction is searched for using the NAI of the mobile nodes  41  and  51  as a key. If a corresponding session transaction is not detected, it is generated. Then, in step S 123 , the mobility binding table is generated.  
     [0255] In step S 124 , the service profile of a mobile node is extracted from the option header of the received packet, and is stored in the service profile cache provided in the home agent. In step S 125 , the communications node list is referred to, and a packet storing the binding update message is transmitted to the communications node registered in the list. In step S 126 , the AAA option containing the HAA message is added to the option header of the packet. Furthermore, in step S 127 , the binding acknowledge message is added to the option header. The packet having this option header is transferred to the AAAH server  22 . Since the destination of the binding acknowledge message is a mobile node, the packet is encapsulated in an IPv6 tunnel packet, and is transmitted to the AAAH server  22 .  
     [0256] As described above, upon receipt of the binding update message, the home agent  21  generates a mobility binding table according to the message. Upon receipt of the HAR message together with the binding update message, the home agent  21  returns the HAA message to the AAAH server  22 , and transfers the binding update message and the service profile to a predetermined communications node as necessary.  
     [0257]FIG. 28 is a flowchart of the process of registering a communications node in the communications node list in the home agent  21 .  
     [0258] In step S 141 , it is checked whether or not the destination IP address of the received packet has been registered in the mobility binding table. If the destination IP address has been registered in the mobility binding table, it is checked in step S 142  whether or not the source IP address of the packet has been registered in the communications node list. If the source IP address has not been registered in the communications node list, then the source IP address is registered in the communications node list in step S 143 .  
     [0259] Then, in step S 144 , the service profile held by the home agent is added to the service profile option in the option header of the received packet. Then, in step S 145 , the packet is transferred to the mobile nodes  41  and  51  by the IPv6 tunnel.  
     [0260] As described above, upon receipt of the packet addressed to a mobile node, the home agent  21  registers the mobile node which has transmitted the packet in the communications node list, and transfers the service profile of the mobile node to the mobile node.  
     [0261] 3.5 AAAF  
     [0262]FIG. 29 is a flowchart of the operations of the AAAF. The flowchart shows the operation performed after the AAAF server  32  receives a packet.  
     [0263] In step S 151 , the type of a received packet is checked. If the received packet is an IPv6 tunnel packet, the processes in and after step S 152  are performed. Otherwise, a corresponding process is performed in step S 171 .  
     [0264] In step S 152 , the type of the message stored in the option header of the received packet is checked. When the binding update message (and the AMR message) is stored in the received packet, the processes in and after step S 153  are performed. On the other hand, when the received packet stores the binding acknowledge message (and the AMA message), the processes in and after step S 161  are performed.  
     [0265] In steps S 153  through S 155 , a session transaction is searched for using the NAI of the mobile nodes  41  and  51  as a key. Here, the NAI of a mobile node is extracted from the option header of a received packet. If a corresponding session transaction is not detected, it is generated. Then, in step S 156 , the AAAH for authenticating a mobile node according to the NAI is specified. Then, the binding update message and the AMR message are transferred to the specified AAAH using an IPv6 tunnel packet.  
     [0266] In step S 161 , the service profile of the mobile node transmitted together with the AMA message is extracted from the option header, and stored in the service profile cache. Then, in step S 162 , the IPv6 packet containing the binding acknowledge message, the AMA message, and the service profile is transferred to the mobile node  41  or the proxy foreign agent  52 . Practically, in the system according to the first embodiment, the IPv6 is transferred to the mobile node  41 . In this case, this packet is not encapsulated. In the system according to the second embodiment, the IPv6 packet is encapsulated and transferred to the proxy foreign agent  52 .  
     [0267] As described above, upon receipt of the binding update message and the AMR message, the AAAF server  32  transfers them to the AAAH. On the other hand, upon receipt of the binding acknowledge message and the AMA message, the AAAF server  32  transfers them to a proxy foreign agent or a mobile node.  
     [0268] 3.6 AAAH  
     [0269]FIG. 30 is a flowchart of the operations of the AAAH. The flowchart shows the operation performed after the AAAH server  22  receives a packet.  
     [0270] In step S 181 , the type of a received packet is checked. If the received packet is an IPv6 tunnel packet, the processes in and after step S 182  are performed. If the received packet is not an IPv6 tunnel packet, a corresponding process is performed in step S 201 .  
     [0271] In step S 182 , the type of the message stored in the option header of the received packet is checked. When the binding update message (and the AMR message) is stored in the received packet, the processes in and after step S 183  are performed. On the other hand, when the received packet stores the binding acknowledge message (and the HAA message), the processes in and after step S 191  are performed.  
     [0272] In step S 183 , according to the NAI of the mobile nodes  41  and  51  stored in the option header of the received packet, a database (SPDB)  23  is accessed to extract a key (an authentication key for the MN-AAA) for authentication of the mobile node. In step S 184 , the mobile node is authenticated using the key.  
     [0273] When the mobile node is successfully authenticated, a session transaction is searched for in steps S 185  and S 186 . At this time, a corresponding session transaction cannot be detected, it is generated.  
     [0274] In step S 187 , the database  23  is accessed again according to the NAI of the above mentioned mobile node to extract the service profile of the mobile node. In step S 188 , the extracted service profile is associated with the above mentioned session transaction. In step S 189 , the extracted service profile is added to the AAA option in the option header of the received packet. At this time, the HAR message is set in the AAA option. Then, in step S 190 , the packet is transferred to the home agent  21 .  
     [0275] In step S 191 , the IPv6 tunnel packet containing the binding acknowledge message and the AMA message is transferred to the AAAF server  32 . The packet stores the service profile of the mobile node.  
     [0276] As described above, upon receipt of the binding update message, the AAAH server  22  authenticates the mobile node, obtains the service profile of the mobile node, and distributes it to the home agent  21 . On the other hand, upon receipt of the binding acknowledge message, the AAAH server  22  transfers it to the AAAF server  32 .  
     [0277] 3.7 Communications node  
     [0278]FIG. 31 is a flowchart of the operations of a communications node. The flowchart shows the operations performed after the communications node  42  receives a packet.  
     [0279] In step S 211 , the type of the message stored in the received packet is checked. If the received packet stores the binding update message, the processes in steps S 212  through S 218  are performed. In steps S 212  through S 214 , a session transaction is searched for according to the NAI of the mobile node. If a corresponding session transaction is not detected, it is generated.  
     [0280] In step S 215 , the address, etc. of the mobile node is extracted from the option header of the received packet, and the binding cache shown in FIG. 12C is generated or updated. In step S 216 , the service profile of the mobile node is extracted from the option header, and is stored in the service profile cache. In step S 217 , it is checked whether or not the “A bit” of the binding update option shown in FIG. 64C is set. If the “A bit” is set, the binding acknowledge message is generated in step S 218 , and is returned to the source of the binding update message. The binding acknowledge message is stored in, for example, the end point option in the option header of the IPv6 packet.  
     [0281] As described above, upon receipt of the binding update message, the communications node  42  generates binding cache for management of the location of the mobile node, and obtains the service profile of the mobile node. The communications node returns the binding acknowledge message to the mobile node as necessary.  
     [0282] 4. Explanation of the sequence of the system according to the first and second embodiments  
     [0283] 4.1 Location registration sequence in the system according to the first embodiment  
     [0284] This sequence is executed immediately after electric power is applied to the mobile node  41 , or when the mobile node  41  moves from the communications area of a router device to the communications area of another router device. The location registration sequence of the mobile node  41  is described below by referring to FIG. 32.  
     [0285] (1) Upon receipt of the ICMPv6 router advertisement message from the router device  31 , the mobile node  41  performs the processes in steps S 53  through S 58  in the flowchart shown in FIG. 22. That is, the mobile node  41  generates an IPv6 packet to transmit the binding update message to the home agent  21 . The binding update message is stored in the option header of the IPv6 packet. The option header is assigned the AAA option containing the AMR message.  
     [0286] The mobile node  41  transmits the packet to the home agent  21 . However, since the packet contains the message of requesting the AAA process, it has to be transferred to the AAA server. Therefore, the packet is encapsulated for transfer to the AAAF server  32 , and is transmitted as an IPv6 packet.  
     [0287] In this sequence, it is assumed that the communications node list is not provided for the mobile node  41 . That is, it is assumed that the processes in steps S 55  and S 56  in the flowchart shown in FIG. 22 are not performed.  
     [0288] (2) Upon receipt of the IPv6 packet containing the binding update message, the router device  31  transfers it to the AAAF server  32 .  
     [0289] (3) Upon receipt of the IPv6 tunnel packet containing the binding update message, the processes in steps S 153  through S 156  in flowchart shown in FIG. 29 are performed. That is, the AAAF server  32  specifies the AAAH corresponding to the mobile node  41  according to the NAI of the mobile node  41  set in the option header of the received packet. Then, the received packet is transferred to the specified AAAH.  
     [0290] (4) Upon receipt of the IPv6 tunnel packet containing the binding update message, the AAAH server  22  performs the processes in steps S 183  through S 190  of the flowchart shown in FIG. 30. That is, after the AAAH server  22  authenticates the mobile node  41 , it extracts the service profile of the mobile node  41  from the database  23 . Then, with the binding update message, the extracted service profile is transferred to the home agent  21 . At this time, the AMR message is replaced with the HAR message.  
     [0291] (5) Upon receipt of the IPv6 packet containing the binding update message and the HAR message, the home agent  21  performs the processes in steps S 121  through S 125  in the flowchart shown in FIG. 27. That is, the home agent  21  generates and updates the mobility binding table according to the binding update message, and obtains the service profile of the mobile node  41  transmitted from the AAAH server  22 . Then, the home agent  21  transmits the binding update message and the service profile of the mobile node  41  to one or more communications nodes registered in the communications node list.  
     [0292] (6) Upon receipt of the IPv6 packet containing the binding update message, the communications node  42  performs the processes in steps S 212  through S 218  of the flowchart shown in FIG. 31. That is, the communications node  42  generates and updates binding cache according to the binding update message, and obtains the service profile of the mobile node  41  transmitted from the AAAH server  22 .  
     [0293] (7) After transmitting the binding update message to the communications node  42 , the home agent  21  performs the processes in steps S 126  and S 127  shown in FIG. 27. That is, the home agent  21  generates an IPv6 packet to return the binding acknowledge message to the mobile node  41 . The binding acknowledge message is stored in the option header of the packet. The AAA option containing the HAA message and the service profile option containing the service profile of the mobile node  41  are added to the option header.  
     [0294] The home agent  21  encapsulates the packet to transfer the IPv6 packet to the AAA server. The IPv6 tunnel packet obtained by the encapsulation is transmitted to the AAAH server  22 .  
     [0295] (8) Upon receipt of the IPv6 tunnel packet containing the binding acknowledge message, the AAAH server  22  performs the process in step S 191  of the flowchart shown in FIG. 30. That is, the AAAH server  22  transfers the received IPv6 tunnel packet to the AAAF server  32 . At this time, the option header of the packet stores the AAA option containing the AMA message, the service profile option containing the service profile of the mobile node  41 , and the MN-AAA authentication extension sub-option indicating the authentication result about the mobile node  41 .  
     [0296] (8) Upon receipt of the IPv6 tunnel packet containing the binding acknowledge message, the AAAF server  32  the processes in steps S 161  and S 162  of the flowchart shown in FIG. 29. That is, the AAAF server  32  decapsulates the received packet, and transfers it to the mobile node  41 .  
     [0297] (10) Upon receipt of the IPv6 packet containing the binding acknowledge message, the router device  31  transfers it to the mobile node  41 .  
     [0298] (11) Upon receipt of the IPv6 packet containing the binding acknowledge message, the mobile node  41  performs the processes in steps S 59  and S 60  of the flowchart shown in FIG. 22. That is, the mobile node  41  obtains the service profile stored in the option header of the received packet.  
     [0299] As described above, in the system according to the first embodiment, the service profile of the mobile node in the location registration sequence is distributed to a predetermined communications appliance. In this sequence, the messages of the AAA protocol and the MIP are stored in the option header of an IPv6 packet, and are then transferred. At this time, the option header is not encrypted. Therefore, the mobile node can be authenticated and registered for location while supporting the IPsec, and can distribute the service profile to the mobile node  41  and the communications node  42 .  
     [0300] 4.2 location Registration Sequence in system according to second embodiment  
     [0301] This sequence is executed immediately after electric power is applied to the mobile node  51 , or when the mobile node  51  moves from the communications area of a proxy foreign agent to the communications area of another proxy foreign agent. The location registration sequence of the mobile node  51  is described below by referring to FIG. 33.  
     [0302] (1) Upon receipt of the ICMPv6 router advertisement message from the proxy foreign agent  52 , the mobile node  51  performs the processes in steps S 57  and S 58  in the flowchart shown in FIG. 24. In this case, the mobile node  51  generates an IPv6 packet to transmit the binding update message to the home agent  21 . The binding update message is stored in the option header of the packet. The option header is assigned the AAA option containing the AMR message. In the system according to the second embodiment, the above mentioned packet is output to a network without being encapsulated, and is transmitted to the proxy foreign agent  52  accommodating the mobile node  51 .  
     [0303] (2) Upon receipt of the IPv6 packet containing the binding update message, the proxy foreign agent  52  performs the processes in step S 82  through S 87  of the flowchart shown in FIG. 25. That is, the proxy foreign agent  52  encapsulates the above mentioned packet so that it can be transferred to the AAA server. The IPv6 tunnel packet obtained by the capsulation is transferred to the AAAF server  32 .  
     [0304] (3) through (8) The processes are the same as those in the sequence according to the first embodiment described by referring to FIG. 32.  
     [0305] (9) Upon receipt of the IPv6 tunnel packet containing the binding acknowledge message, the AAAF server  32  performs the processes in steps S 161  and S 162  of the flowchart shown in FIG. 29. That is, the AAAF server  32  transfers the received packet to the proxy foreign agent  52 .  
     [0306] (10) Upon receipt of the IPv6 tunnel packet containing the binding acknowledge message, the proxy foreign agent  52  performs the processes in steps S 101  and S 103  of the flowchart shown in FIG. 25. That is, the proxy foreign agent  52  obtains the service profile of the mobile node  51  from the option header of the received packet, and stores it in the service profile cache. Then, it transfers the IPv6 packet containing the binding acknowledge message to the mobile node  51 .  
     [0307] (11) The mobile node  51  receives the binding acknowledge message, thereby terminating the location registration sequence.  
     [0308] As described above, the system according to the second embodiment is basically the same as the system according to the first embodiment. However, the service profile of a mobile node is not distributed to the mobile node, but to a proxy foreign agent. Then, the proxy foreign agent provides a communications service based on the service profile. Therefore, the configuration of the mobile node can be simpler than in the system according to the first embodiment.  
     [0309] 4.3 Setting binding cache of communications node (when a communications node list is provided in a home agent)  
     [0310] The sequence is executed when a data packet is transferred to the mobile nodes  41  and  51  from the communications node  42 . The sequence is described below by referring to  34 .  
     [0311] (1) The communications node  42  transmits a data packet (IPv6 packet) to the mobile nodes  41  and  51 . At this time, it is assumed that the communications node  42  does not have binding cache for the mobile nodes  41  and  51 . In this case, the communications node  42  transmits the above mentioned data packet to the home addresses of the mobile nodes  41  and  51 . Therefore, the data packet is first transmitted to the home agent  21 .  
     [0312] (2) Upon receipt of the data packet addressed to the mobile nodes  41  and  51 , the home agent  21  performs the processes in steps S 7  through S 10  of the flowchart shown in FIG. 20. That is, the home agent  21  registers the communications node  42  in the communications node list. As shown in FIG. 28, the procedure of registering a communications node in the home agent  21  includes the process of adding the service profile of the mobile nodes  41  and  51  to the option header of a packet, and the process of transferring the packet to the mobile nodes  41  and  51 . As a result, an IPv6 tunnel packet obtained by adding the service profile of the mobile nodes  41  and  51  to the option header of the data packet is transferred from the home agent  21  to the mobile nodes  41  and  51 .  
     [0313] (3) The above mentioned IPv6 tunnel packet is transmitted to the router device  31  accommodating the mobile node  41  or the proxy foreign agent  52 . Then, the router device  31  or the proxy foreign agent  52  transfers the packet to the mobile node  41 .  
     [0314] (4) Upon receipt of the IPv6 tunnel packet from the home agent  21 , the mobile nodes  41  and  51  perform the processes in steps S 3  through S 5  of the flowchart shown in FIG. 20. It is assumed that no communications node list is provided in the mobile nodes  41  and  51 . Therefore, the mobile nodes  41  and  51  perform the process in step S 4  by skipping the process in step S 3 . The practical process in step S 4  is shown in FIG. 22 or  24 . That is, upon receipt of the IPv6 tunnel packet, the mobile nodes  41  and  51  transmit the binding update message to the communications node  42  in step S 61 . The binding update message is stored in the option header of the IPv6 packet addressed to the communications node. At this time, the option header of the IPv6 packet also stores the service profile of the mobile nodes  41  and  51  transmitted from the home agent  21 .  
     [0315] (5) Upon receipt of the IPv6 packet addressed to the communications node  42  containing the binding update message, the router device  31  or the proxy foreign agent  52  transmits it to the router device accommodating the communications node  42 . In the system according to the second embodiment, the process in step S 91  shown in FIG. 25 corresponds to the above mentioned process.  
     [0316] (6) The router device accommodating the communications node  42  receives the packet and transfers it to the communications node  42 .  
     [0317] (7) Upon receipt of the IPv6 packet containing the binding update message, the communications node  42  performs the processes in steps S 212  through S 218  of the flowchart shown in FIG. 31. That is, the communications node  42  generates or updates binding cache according to the binding update message, and obtains the service profile of the mobile nodes  41  and  51  from the option header. Furthermore, it generates an IPv6 packet containing the binding acknowledge message, and returns it to the mobile nodes  41  and  51 . At this time, the packet is transmitted to the address obtained according to the binding update message.  
     [0318] (8) The packet containing the binding acknowledge message is transmitted to the router device  31  or the proxy foreign agent  52 .  
     [0319] (9) The router device  31  or the proxy foreign agent  52  transfers the received packet to the mobile nodes  41  and  51 .  
     [0320] Thus, according to the above mentioned sequence, a communications node which transmits a packet to a mobile node can recognize the location of the mobile node (currently assigned address) by receiving a binding update message from the mobile node. At this time, the service profile of the mobile node is distributed to the communications node. Therefore, a value added service prescribed by a service profile is provided not only for the communications from the mobile node to the communications node, but also for the communications from the communications node to the mobile node.  
     [0321] 4.4 Setting binding cache of communications node (when a communications node list is provided for a mobile node)  
     [0322] The sequence shown in FIG. 34 is based on that a communications node list is provided for the home agent  21 . On the other hand, this sequence is based on that a communications node list is provided for the mobile node  41  of the system according to the first embodiment, and is described below by referring to FIG. 35.  
     [0323] (1) The communications node  42  transmits a data packet to the mobile node  41 . At this time, it is assumed that the communications node  42  does not have binding cache for the mobile node  41 . The communications node  42  transmits the above mentioned data packet to the home address of the mobile node  41 . Therefore, the data packet is first transmitted to the home agent  21 .  
     [0324] (2) Upon receipt of the data packet addressed to the mobile node  41 , the home agent  21  performs the processes in steps S 7  through S 10  of the flowchart shown in FIG. 20. However, the home agent  21  is not provided with a communications node list. In this example, it is assumed that the home agent  21  does not transmit a service profile of the mobile node  41 . Therefore, the home agent  21  performs only the processes in step S 145  shown in FIG. 28. That is, the home agent  21  transfers the packet received from the communications node  42  to the mobile node  41 . At this time, the transferred packet is an IPv6 tunnel packet.  
     [0325] (3) The above mentioned IPv6 tunnel packet is transmitted to the router device  31  accommodating the mobile node  41 . The router device  31  transfers the packet to the mobile node  41 .  
     [0326] (4) Upon receipt of the IPv6 tunnel packet transmitted from the home agent  21 , the mobile node  41  performs the processes in steps S 3  through S 5  shown in FIG. 20. That is, the mobile node  41  first registers the communications node  42  which is the source of the data packet in the communications node list. Then, the mobile node  41  transmits the binding update message to the communications node  42  by performing the processes in step S 61  shown in FIG. 22. The binding update message is stored in the option header of the IPv6 packet addressed to the communications node. At this time, the option header of the IPv6 packet also stores the service profile of the mobile node  41  stored in the service profile cache of the mobile node  41 .  
     [0327] (5) through (9) The processes are the same as those described above by referring to FIG. 34.  
     [0328] As described above, in the sequence shown in FIG. 35, the service profile stored in the service profile of the mobile node  41  is transmitted together with the binding update message to the communications node.  
     [0329] 4.5 Setting binding cache of communications node (when a communications node list is provided for a proxy foreign agent)  
     [0330] The sequence shown in FIGS. 34 and 35 is based on that a communications node list is provided for the home agent  21  and the mobile node  41 , respectively. On the other hand, this sequence is based on that a communications node list is provided for the proxy foreign agent  52  in the system according to the second embodiment, and described below by referring to FIG. 36.  
     [0331] (1) and (2) refer to the processes the same as the processes described above by referring to FIG. 35.  
     [0332] (3) The IPv6 tunnel packet from the home agent  21  is transmitted to the proxy foreign agent  52  accommodating the mobile node  51 . Upon receipt of the IPv6 tunnel packet, the proxy foreign agent  52  performs the processes in steps S 12  and S 11  of the flowchart shown in FIG. 20. That is, the proxy foreign agent  52  registers the communications node  42  which is the source of the data packet in the communications node list. Then, the IPv6 tunnel packet is transferred to the mobile node  51 .  
     [0333] (4) Upon receipt of the packet, the mobile node  51  performs the process in step S 61  of the flowchart shown in FIG. 24. That is, it generates an IPv6 packet containing a binding update message, and transmits it to the communications node  42 .  
     [0334] (5) Upon receipt of the IPv6 packet containing the binding update message, the proxy foreign agent  52  performs the processes in steps S 89  through S 91  of the flowchart shown in FIG. 25. That is, the proxy foreign agent  52  first stores the service profile of the mobile node  51  in the option header of the IPv6 packet received from the mobile node  51 . The service profile is held in the service profile cache of the proxy foreign agent  52 . Then, the proxy foreign agent  52  transfers the IPv6 packet containing the binding update message and the service profile of the mobile node  51  to the communications node  42 .  
     [0335] (6) through (9) refer to the processes the same as those described above by referring to FIG. 34.  
     [0336] As described above, in the sequence shown in FIG. 36, the service profile stored in the service profile cache of the proxy foreign agent  52  is transmitted to the communications node together with the binding update message.  
     [0337] 5. Outline of the third and fourth embodiments  
     [0338]FIG. 37 shows the configuration of the network of the communications service providing system according to the third and fourth embodiments of the present invention. The system according to the third and fourth embodiments is designed based on the system according to the first and second embodiments, respectively.  
     [0339] In the system according to the third and fourth embodiments, one or more DHCP servers are provided in an external network. The DHCP server is an address server for managing the address to be assigned to a terminal in a local domain. That is, the mobile nodes  61  and  71  access the DHCP server  63  and obtain an address when a power switch is turn ON, or when they are moved from the communications area of a router device to the communications area of another router device.  
     [0340]FIG. 38 shows the configuration of the main devices of the communications service providing system according to the third embodiment. The home agent  21 , the AAAH server  22 , the AAAF server  32 , and the communications node  42  are basically the same as the systems according to the first or second embodiment.  
     [0341] The mobile node  61  is provided with the DHCP client function in addition to corresponding function provided in the mobile node  41  used according to the first embodiment. In this example, the “DHCP client” requests the DHCP server  63  to transmit the address temporarily used by the mobile node  61 . The router device  62  accommodates the DHCP server  63 . The DHCP server  63  is provided with a packet control unit and a protocol control unit. In addition, the protocol control unit has the DIAMETER client function (DCF) and the DHCP server function. The “DHCP server” assigns an address to the terminal at the DHCP request from the terminal (including the mobile node  61 ).  
     [0342]FIG. 39 shows the configuration of the main devices of the communications service providing system according to the fourth embodiment of the present invention. The system according to the fourth embodiment has a smaller number of functions provided for a mobile node than the system according to the third embodiment. That is, the mobile node  71  is not provided with a service control unit, service profile cache, and a DIAMETER client function (DCF). These functions are provided for the proxy foreign agent  72 .  
     [0343] In the systems according to the third and fourth embodiments, the mobile nodes  61  and  71  are authenticated in the AAAH server  22  when the mobile nodes  61  and  71  request the DHCP server  63  to transmit an address. In the authentication procedure, the service profiles of the mobile nodes  61  and  71  are distributed to a predetermined communications appliance (including the mobile node  61 ). At this time, each type of information (including a DHCP request message) is stored in an IPv6 packet and transmitted. Described below is the configuration of the packet used in the system according to third and fourth embodiments.  
     [0344]FIG. 70 shows the format of the IP packet stored in the DHCP message. The IPv6 packet comprises an IP header and an IP payload as described above, and a UDP packet is stored in the IP payload. The UDP packet comprises a UDP header and a UDP payload. The DHCP message is stored in the UDP payload. The DHCP message comprises a DHCP header and a DHCP payload.  
     [0345]FIGS. 71A through 71C show the format of the information relating to a DHCP request. FIG. 71A shows the format of a DHCP request message. A transaction ID and various addresses are set in a DHCP request message. The message is stored in the DHCP header.  
     [0346]FIG. 71B shows the format of the MN-NAI extension. The NAI of a mobile node is set in this extension area. FIG. 71C shows the format of the MN-AAA extension. Data (AAA data) relating to an AAA protocol is stored in this extension area. In this embodiment, the AAA protocol is DIAMETER. The extension data is stored in a DHCP payload.  
     [0347]FIGS. 72A through 72C show the format of the information relating to a DHCP reply. FIG. 72A shows the format of a DHCP reply message. A status, a transaction ID, a client address, etc. are set in the DHCP reply message. The status indicates the result of the DHCP request, etc. The message is stored in the DHCP header.  
     [0348]FIG. 72B shows the format of the MN-AAA extension. Data (AAA data) relating to an AAA protocol is stored in this extension area. The extension data is stored in the DHCP payload. FIG. 72C shows the format of the service profile cache extension stored in the DHCP reply message. The data field of this extension area stores the service profile of the mobile node extracted from the database  23 . The service profile cache extension is stored in the AAA data area of the MN-AAA extension shown in FIG. 72B.  
     [0349]FIG. 73 shows the format of the IPv6 packet storing the information about the DIAMETER according to the third and fourth embodiments. The information about the DIAMETER is stored in the option header of the IPv6 packet according to the first and second embodiments, but in the UDP payload according to the third and fourth embodiments. The information about the DIAMETER comprises a DIAMETER common header and an AVP (attribute value pair) group.  
     [0350]FIG. 74 shows the format of the UDP header. A port number, a data length, etc. are set in the UDP header.  
     [0351]FIG. 75 shows the format of the DIAMETER common header. An identifier, etc. for one-to-one correspondence between a registration request message and a registration reply message is set in the DIAMETER common header.  
     [0352]FIGS. 76A through 76C show the format of the AVP group. FIG. 76A shows the basic format of the AVP. If the AVP code=256 is set in this format, it refers to a command (or a message). FIG. 76B shows the format of the DIAMETER command AVP. In this format, the type of message (AMR, AMA, HAR, HAA, etc.) is identified. FIG. 76C shows a typical format of the AVP other than a command. The service profile of the mobile node extracted from the database  23  can be stored in the data area of the AVP group.  
     [0353]FIGS. 77A through 77D show the format of the DIAMETER message used in the system according to the third and fourth embodiments.  
     [0354]FIG. 77A shows the format of the AMR message including a DHCP request. This message is obtained by adding the DHCP request AVP and the service profile cache AVP to a common AMR message. FIG. 77B shows the format of the AMA message including a DHCP reply. The message can be obtained by adding the DHCP reply AVP and the service profile cache AVP to a common AMA message.  
     [0355]FIG. 77C shows the format of an FDR (FA DHCP request) message. An FDR message notifies the proxy foreign agent  72  of the DHCP request from the DHCP server  63 , and comprises a DIAMETER header, an FA-DHCP request command, a session ID, a user name, a DHCP request, and a time stamp. FIG. 77D shows the format of an FDA (FA DHCP answer) message. An FDA message notifies the DHCP server  63  of the DHCP reply from the proxy foreign agent  72 , and comprises a DIAMETER header, and an FA-DHCP reply command, a session ID, a result code, and a time stamp. The formats of the FDR message and the FDA message are based on the DIAMETER.  
     [0356]FIGS. 78A through 78C show the format of the service profile cache AVP. This AVP is stored in the AMR message shown in FIG. 77A, and the AMA message shown in FIG. 77B.  
     [0357]FIG. 78A shows the basic format of the service profile cache AVP stored in the AMR message or the AMA message. FIG. 78B shows the header of the profile data area of the service profile cache AVP. The service profile is managed by the session ID (NAI of a mobile node) set in the header. FIG. 78C shows an example of a service profile stored as the profile data of the service profile cache AVP.  
     [0358] 6. Flowchart of the operations of each device in the third or fourth embodiment  
     [0359] In the system according to the third or fourth embodiment, in the AAA process started according to the DHCP request, a message relating to an AAA protocol is basically stored in the payload of a UDP packet. If a service profile of a mobile node is distributed in this AAA process, the service profile is also stored in the UDP packet. On the other hand, when the location of a mobile node is registered in a home agent or a communications node after the above mentioned AAA process, the message used in the location registering process is basically stored in the option header of the IPv6 packet. When a service profile of a mobile node is distributed in this location registering process, the service profile is also stored in the option header of the IPv6 packet.  
     [0360] 6.1 Mobile node  
     [0361]FIG. 40 is a flowchart of the operation of a mobile node according to the third embodiment. The flowchart shows the operation performed after the mobile node  61  has received a packet.  
     [0362] In step S 301 , the type of a received packet is checked. If the received packet is an IPv6 tunnel packet, the processes in and after step S 302  are performed. If the received packet is an IPv6 packet, the processes in and after step S 311  are performed. If the received packet is not an IPv6 tunnel packet or an IPv6 packet, a corresponding process is performed in step S 321 .  
     [0363] In step S 302 , it is checked whether or not a service profile is stored in the service profile cache provided in the mobile node  61 . If such a service profile exists, the above mentioned service profile is stored in the end point option in the option header of the IPv6 packet in step S 303 . In step S 304 , the binding update message is stored in the option header. Then, the IPv6 packet with the option header is transmitted to the communications node  42 .  
     [0364] In step S 311 , the type of message stored in the received packet is checked. If the binding request message is received, control is passed to step S 302 . If the ICMP router advertisement message is received, control is passed to step S 312 . If the DHCP reply message is received, control is passed to step S 314 .  
     [0365] In step S 312 , it is checked whether of not the source address of the received advertisement message has been registered in the agent list. The agent list is described above in relation to step S 53  shown in FIG. 22. If the source address of the received advertisement message has not been registered in the agent list, the DHCP message is transmitted to the DHCP server  63  in step S 313 . The DHCP request message is stored in the IPv6 packet and transferred as described above by referring to FIGS. 70 and 71.  
     [0366] In step S 314 , the service profile transmitted together with the DHCP reply message is obtained. The service profile is stored in the service profile cache provided in a mobile node. In step S 315 , the above mentioned service profile is stored in the end point option in the option header of the IP packet. In step S 316 , the binding update message is stored in the option header. Then, the IPv6 packet with that option header is transmitted to the home agent  21 .  
     [0367]FIG. 41 is a flowchart of the operations of a mobile node according to the fourth embodiment. The operations of the mobile node  71  according to the fourth embodiment is basically the same as the operations of the mobile node  61  according to the third embodiment shown in FIG. 40. However, the mobile node  71  according to the fourth embodiment is not provided with a service profile cache. Therefore, the process of obtaining a service profile from a received packet, and the process of distributing a service profile to a home agent or a communications node are not performed. That is, the mobile node  71  does not perform the processes in step S 302 , S 303 , S 314 , and S 315  of the flowchart shown in FIG. 40.  
     [0368] As described above, upon receipt of the IPv6 tunnel packet from the communications node  42 , the mobile node in the system according to the third and fourth embodiments transmits the binding update message to the communications node  42 . In addition, upon receipt of the router advertisement message, it transmits the DHCP request message to the DHCP server  63 . Furthermore, upon receipt of the DHCP reply message, it transmits the binding update message to the home agent  21 . According to the third embodiment, the service profile of the mobile node is distributed to the home agent and the communications node.  
     [0369] 6.2 Proxy foreign agent  
     [0370]FIGS. 42 and 43 are flowcharts of the operations of the proxy foreign agent. This flowchart shows the operations performed after the proxy foreign agent  72  receives a packet. The proxy foreign agent  72  is provided in the system according to the fourth embodiment.  
     [0371] In steps S 341  and S 342 , a received packet is filtered using a source address and a destination address. If the source of the received packet is a predetermined DHCP server  63  or a target mobile node, then the processes in and after step S 343  are performed. If the destination of the received packet is the proxy foreign agent  72 , then the processes in and after step S 361  are performed. If the above mentioned two cases are not applied, a received packet is processed and transferred according to the service profile provided for the proxy foreign agent  72  in steps S 351  and S 352 .  
     [0372] In step S 343 , the type of the message stored in the received packet is checked. If the binding update message is received, the processes in and after step S 344  are performed. If the AMR message is received, the processes in and after step S 347  are performed. If the above mentioned two messages are not received, then the received packet is transferred according to the destination address in step S 350 .  
     [0373] In step S 344 , a session transaction is retrieved using the IP address of the mobile node  71 . Thus, the service profile of the mobile node  71  is extracted. Then, in step S 345 , the service profile extracted in step S 344  is added to the relay point option in the option header of the IPv6 packet. In step S 346 , the binding update message is added to the option header. Then, the IPv6 packet with that option header is transferred to the destination (home agent  21  or communications node  42 ).  
     [0374] In steps S 347  and S 348 , the session transaction is searched for using the user NAI of the mobile node  71 . When a corresponding session transaction is not detected, it is generated. Then, in step S 349 , a received packet containing the AMR message is transferred to the AAAF server  32 .  
     [0375] In step S 361 , the type of the message stored in the received packet is checked. If the AMA message is received, the processes in and after step S 362  are performed. If the FDR message is received, the processes in and after step S 364  are performed. If the AMA message or the FDR message is not received, then a corresponding process is performed in step S 371 .  
     [0376] In step S 362 , a service profile transmitted together with the AMA message is obtained. The service profile is stored in the service profile cache provided for the proxy foreign agent  72 .  
     [0377] The process in step S 363  depends on whether the system uses the FDR and the FDA. That is to say, in the system which does not use the FDR and the FDA, the packet containing the AMR message is transferred to the DHCP server  63  in step S 363 . On the other hand, in the system using the FDR and the FDA, the FDA message is generated in step S 363 , and the FDA message is transmitted to the DHCP server  63  instead of the AMA message. The format of the FDA message is shown in FIG. 77D.  
     [0378] In steps S 364  through S 366 , the session transaction is searched for using the user NAI of the mobile node  71 . If a corresponding session transaction is not detected, it is generated. Then, an AMR message is generated and transmitted to the AAAF server  32  in step S 367 . The AMR message is set using the AVP shown in FIG. 76.  
     [0379] As described above, upon receipt of the binding update message, the proxy foreign agent  72  transmits the message together with the service profile of the mobile node  71  to the home agent  21  or the communications node  42 . Upon receipt of the AMR message, it transfers the received message to the AAAF server  32 . Upon receipt of the AMA message, it transfers the message to the DHCP server  63 . Upon receipt of the FDR message, it transmits the AMR message to the AAAF server  32 .  
     [0380] 6.3 DHCP server  
     [0381]FIG. 44 is a flowchart of the operations of the DHCP server. The flowchart shows the operation performed after the DHCP server  63  receives a packet. In this example, the FDR message and the FDA message are not used.  
     [0382] In step S 371 , the type of the message stored in the received packet is checked. When the AMA message is received, the DHCP reply message is generated and transmitted to the mobile nodes  61  and  71  in step S 372 . The DHCP reply message is stored in the IPv6 packet and transferred as shown in FIGS. 70 and 72.  
     [0383] When the DHCP request message is received, the processes in steps S 373  through  375  are performed. In steps S 373  and S 374 , the session transaction is searched for using the user NAI of the mobile node. Then, a corresponding session transaction is not detected, it is generated. Then, in step S 375 , the AMR message is generated and transmitted to the AAAF server  32 .  
     [0384] If the AMA message or the DHCP request message has not been received, a corresponding process is performed in step S 381 .  
     [0385] As described above, upon receipt of the AMA message, the DHCP server  63  transmits the DHCP reply message to the mobile nodes  61  and  71 . Upon receipt of the DHCP request message, it transmits the AMR message to the AAAF server  32 .  
     [0386]FIG. 45 is a flowchart of the operations of the DHCP server when the FDR message and the FDA message are used.  
     [0387] In the system in which the FDR message and the FDA message are used, the DHCP server  63  transmits the DHCP reply to the mobile nodes  61  and  71  when the FDA message is received (step S 391 ). In addition, upon receipt of the DHCP request message, the DHCP server  63  transmits the FDR message to the AAAF server  32  (step S 392 ).  
     [0388] 6.4 Home agent  
     [0389]FIG. 46 is a flowchart of the operations of a home agent. The flowchart shows the operations performed after the home agent  21  receives a packet.  
     [0390] In step S 401 , the type of the message stored in the received packet is checked. When the binding update message is received, the processes in and after step S 402  are performed. Otherwise, a corresponding process is performed in step S 421 .  
     [0391] In steps S 402  through S 404 , the session transaction is searched for using the user NAI of the mobile node. If a corresponding session transaction is not detected, it is generated. Afterwards, the process relating to the information stored in the option header of the received IPv6 packet is performed.  
     [0392] In step S 405 , the type of the option stored in the option header is checked. If the end point option is stored, then the processes in steps S 411  through S 417  (excluding steps S 414  and S 415 ) are performed. If the relay point option is stored, the processes in steps S 414  through S 417  are performed. In the case other than the above mentioned two cases, a corresponding process is performed in step S 418 .  
     [0393] In step S 411 , the mobile nodes  61  and  71  are registered based on the binding update option stored in the end point option, thereby generating or updating the mobility binding table. In steps S 412  and S 413 , the service profiles of the mobile nodes  61  and  71  are extracted from the service profile option in the end point option. On the other hand, in steps S 414  and S 415 , the service profiles of the mobile nodes  61  and  71  are extracted from the service profile option in the relay point option.  
     [0394] In step S 416 , it is checked whether or not the A-bit of the binding update option shown in FIG. 64C is set. If the A bit is set, the IPv6 packet containing the binding acknowledge message is generated, and transmitted to the mobile nodes  61  and  71  in step S 417 .  
     [0395] As described above, upon receipt of the binding update message, the home agent  21  obtains the service profile transmitted together with the message, and returns the binding acknowledge message to the mobile node.  
     [0396] 6.5 AAAF  
     [0397]FIG. 47 is a flowchart of the operations of the AAAF. The flowchart shows the operations performed after the AAAF server  32  receives a packet.  
     [0398] The operations of the AAAF server  32  in the system according to the third or fourth embodiment are basically the same as those according to the first or second embodiment. However, in the system according to the third or fourth embodiment, the AAAF server  32  does not receive the binding update message or the binding acknowledge message.  
     [0399] In step S 43 , the type of the message stored in the received packet is checked. When the AMR message is received, the processes in and after step S 432  are performed. When the AMA message is received, the processes in steps S 436  and S 437  are performed. When the AMR message or the AMA message is not received, a corresponding process is performed in step S 441 .  
     [0400] In steps S 432  through S 434 , a session transaction is searched for using the user NAI of the mobile node. If a corresponding session transaction is not detected, it is generated. In step S 435 , the AAAH of the mobile node is specified based on the user NAI of the mobile node. Then, the packet containing the AMR message is transferred to the specified AAAH.  
     [0401] In step S 436 , the service profile of the mobile node transmitted together with the AMA message is obtained, and it held as being associated with the session transaction. In step S 437 , based on the session, the packet containing the AMA message is transferred to the proxy foreign agent  72  or the DHCP server  63 . Thus, the service profile of the mobile node is distributed to the proxy foreign agent  52  or the DHCP server  63 .  
     [0402] As described above, upon receipt of the AMR message, the AAAF server  32  transfers it to the AAAH server  22 . Upon receipt of the AMA message (and the service profile of the mobile node), it is transferred to the proxy foreign agent  52  or the DHCP server  63 .  
     [0403] 6.6 AAAH  
     [0404]FIG. 48 is a flowchart of the operations of the AAAH. This flowchart shows the operations performed after the AAAH server  22  receives a packet.  
     [0405] The operations of the AAAH server  22  in the system according to the third or fourth embodiment are basically the same as those according to the first or second embodiment. However, in the system according to the third or fourth embodiment, the AAAH server  22  does not receive the binding update message and the binding acknowledge message.  
     [0406] In step S 451 , the type of the message stored in the received packet is checked. If the AMR message is received, the processes in and after step S 452  are performed. Otherwise, a corresponding process is performed in step S 461 .  
     [0407] In steps S 452  and S 453 , the mobile node is authenticated. In steps S 454  and S 455 , a session transaction is searched for. In step S 456 , a service profile corresponding to the mobile node is extracted. In step S 457 , the service profile extracted in step S 456  is held as being associated with the session transaction. Then, in step S 458 , a packet containing the AMA message and the extracted service profile is transmitted to the AAAF server  32 .  
     [0408] When the mobile node cannot be successfully authenticated, the AMA message containing an error code is transmitted to the AAAF server  32 .  
     [0409] As described above, upon receipt of the AMR message, the AAAH server  22  first authenticates the mobile node, and then returns the AMA message to the AAAF server  32 . At this time, the service profile of the mobile node is transmitted together with the AMA message to the AAAF server  32 .  
     [0410] 6.7 Communications node  
     [0411]FIG. 49 is a flowchart of the operations of the communications node. The flowchart shows the operations performed after the communications node  42  receives a packet.  
     [0412] The operations of the communications node  42  are basically the same as the operations of the home agent  21  shown in FIG. 46. However, the home agent  21  performs a home registering process when it receives a binding update message (step S 412 ), while the communications node  42  generates or updates binding cache when it receives a binding update message (step S 471 ).  
     [0413] 7. Explanation of the sequence of the third and fourth embodiments  
     [0414] 7.1. Sequence of distributing a service profile in the system according to the third embodiment  
     [0415] This sequence is performed immediately after electric power is applied to the mobile node  61 , or when the mobile node  61  moves from the communications area of a router device to the communications area of another router device. The DHCP-AAA cooperation started by a DHCP request is described below by referring to FIG. 50.  
     [0416] (1) The router device  102  transmits an ICMP router advertisement message.  
     [0417] (2) Upon receipt of the advertisement message, the mobile node  61  performs the processes in steps S 312  and S 313  of the flowchart shown in FIG. 42. That is, the mobile node  61  transmits a DHCP request message to the DHCP server  63  to inquire about the address. The DHCP server  63  is the nearest DHCP server. The DHCP request message has the format shown in FIG. 71, and is stored in a UDP packet. The UDP packet is stored in the payload of the IPv6 packet.  
     [0418] (3) Upon receipt of a packet containing a DHCP request message, the DHCP server  63  performs the processes in steps S 373  through S 375  of the flowchart shown in FIG. 44 to request the AAA process. That is, the DHCP server  63  generates an AMR message containing the DHCP request message, and transmits it to the AAAF server  32 . The AMR message containing the DHCP request message has the format shown in FIG. 77A, and is stored in the UDP packet.  
     [0419] (4) Upon receipt of the AMR message, the AAAF server  32  performs the processes in steps S 432  through S 435  of the flowchart shown in FIG. 47. That is, the AAAF server  32  extracts the NAI of the mobile node  61  from the received packet, specifies the AAAH server  22  for performing the AAA process for the mobile node  61  based on the NAI, and then transfers the packet containing the AMR message to the AAAH server  22 .  
     [0420] (5) Upon receipt of the packet containing the AMR message, the AAAH server  22  performs the processes in steps S 452  through S 458  of the flowchart shown in FIG. 48. That is, the AAAH server  22  first authenticates the mobile node  61  using the MN-AAA authentication extension sub-option stored in the received packet. Then, it extracts the service profile of the mobile node  61  from the database  23 , generates an AMA message containing the service profile, and returns it to the AAAF server  32 . The AMA message storing the service profile has the format shown in FIG. 77B, and is stored in the UDP packet. However, at this time, no DHCP reply message is stored in the AMA message.  
     [0421] (6) Upon receipt of the packet containing the AMA message, the AAAF server  32  performs the processes in steps S 436  and S 437  of the flowchart shown in FIG. 47. Here, the AAAF server  32  has received the AMR message from the DHCP server  63  in (4) above. Therefore, the AAAF server  32  transfers the packet received from the AAAH server  22  to the DHCP server  63 .  
     [0422] (7) Upon receipt of the packet containing the AMA message, the DHCP server  63  performs the process in step S 372  of the flowchart shown in FIG. 44. That is, the DHCP server  63  generates a DHCP reply message, and transmits it to the mobile node  61 . At this time, the DHCP reply message is stored in the AMA message shown in FIG. 77B. Thus, the AMA message, the DHCP reply message, and the service profile of the mobile node  61  are transferred from the DHCP server  63  to the mobile node  61 .  
     [0423] (8) Upon receipt of the DHCP reply message, the mobile node  61  performs the processes in steps S 314  through S 316  of the flowchart shown in FIG. 40. That is, the mobile node  61  first stores the received service profile in the service profile cache, stores the binding update message and the service profile in the end point option in the option header of the IPv6 packet, and transmits the packet to the home agent  21 .  
     [0424] (9) Upon receipt of the IPv6 packet containing the binding update message, the home agent  21  performs the processes in steps S 402  through S 417  of the flowchart shown in FIG. 46. That is, the home agent  21  first performs the home registration of the mobile node  61 . Thus, a mobility binding table is generated or updated. Then, the service profile transmitted together with the binding update message is obtained and stored in the service profile cache. After that, the binding acknowledge message is returned to the mobile node  61 . The binding acknowledge message is stored in the end point option in the option header of the IPv6 packet.  
     [0425] (10) The communications node  42  transmits a data packet to the mobile node  61 . At this time, it is assumed that the communications node  42  is not informed of the address currently assigned to the mobile node  61 . Therefore, the communications node  42  transmits the data packet to the home address of the mobile node  61 . In this case, the packet is encapsulated into an IPv6 tunnel packet by the home agent  21 , and is transferred to the mobile node  61 .  
     [0426] (11) Upon receipt of the IPv6 tunnel packet, the mobile node  61  performs the processes in steps S 302  through S 304  of the flowchart shown in FIG. 40. That is, the mobile node  61  retrieves the service profile from the service profile cache, stores the binding update message and the service profile in the end point option in the option header of the IPv6 packet, and then transmits the packet to the communications node  42 .  
     [0427] (12) Upon receipt of the IPv6 packet containing the binding update message, the communications node  42  performs the processes in steps S 402  through S 413  (containing step S 471 ) of the flowchart shown in FIG. 49. That is, the communications node  42  first generates (or updates) the binding cache according to the binding update message, obtains the service profile transmitted together with the binding update message, and stores it in the service profile cache.  
     [0428] Thus, in the above mentioned sequence, the AAA process sequence for the mobile node  61  is performed at the DHCP request, and a service profile is distributed to the mobile node  61  in the AAA process sequence. When the DHCP process is completed, the location of the mobile node  61  is registered in the home agent  21 . In the location registration sequence, the service profile is distributed from the mobile node  61  to the home agent  21 . Furthermore, the service profile is distributed to the communications node  42  which has transmitted the packet to the mobile node  61 .  
     [0429] 7.2 Sequence of distributing a service profile in the system according to the fourth embodiment  
     [0430] This sequence is performed immediately after electric power is applied to the mobile node  71  or when the mobile node  71  moves from the communications area of a router device to the communications area of another router device. The DHCP-AAA cooperation started by a DHCP request is described below by referring to FIG. 51. In this example, it is assumed that the DHCP server  63  is accommodated in the proxy foreign agent  72 . The proxy foreign agent  72  captures and analyzes all packets transmitted by the DHCP server  63 .  
     [0431] (1) The proxy foreign agent  72  transmits an ICMP router advertisement message.  
     [0432] (2) The process (2) shown in FIG. 50 is performed. That is to say, upon receipt of the advertisement message, the mobile node  61  transmits the DHCP request message to the DHCP server  63 .  
     [0433] (3) The process (3) shown in FIG. 50 is performed. That is to say, upon receipt of the packet containing the DHCP request message, the DHCP server  63  generates an AMR message containing the DHCP request message, and transmits it to the AAAF server  32 .  
     [0434] (4) Upon receipt of the packet transmitted from the DHCP server  63 , the proxy foreign agent  72  performs the process in step S 350  of the flowchart shown in FIG. 42. That is, the proxy foreign agent  72  transfers the AMR message containing the DHCP request message to the AAAF server  32 .  
     [0435] The processes (5) and (6) are the same as the processes (4) and (5) shown in FIG. 50. That is, the AMR message is transferred from the AAAF server  32  to the AAAH server  22 , and the AMA message is returned from the AAAH server  22  to the AAAF server  32 . The AMA message stores the service profile of the mobile node  71 .  
     [0436] (7) Upon receipt of the packet containing the AMA message, the AAAF server  32  performs the processes in steps S 436  and S 437  of the flowchart shown in FIG. 47. The AAAF server  32  has received the AMR message from the proxy foreign agent  72  in the process (5) above. Therefore, the AAAF server  32  transfers the packet received from the AAAH server  22  to the proxy foreign agent  72 .  
     [0437] (8) Upon receipt of the packet containing the AMA message, the proxy foreign agent  72  performs the processes in steps S 362  and S 363  of the flowchart shown in FIG. 43. That is, the proxy foreign agent  72  first obtains the service profile of the mobile node  71  from the received packet, stores it in the service profile cache, and transfers the packet containing the AMA message to the DHCP server  63 .  
     [0438] (9) The process (7) shown in FIG. 50 is performed. That is, upon receipt of the packet containing the AMA message, the DHCP server  63  generates a DHCP reply message, and transmits it to the mobile node  71 . At this time, the DHCP reply message is stored in the AMA message.  
     [0439] (10) Upon receipt of the DHCP reply message, the mobile node  71  performs the process in step S 316  of the flowchart shown in FIG. 41. That is, the mobile node  61  stores the binding update message in the end point option in the option header of the IPv6 packet, and transmits the packet to the home agent  21 .  
     [0440] (11) Upon receipt of the packet containing the binding update message, the proxy foreign agent  72  performs the processes in steps S 344  through S 346  of the flowchart shown in FIG. 42. That is, the proxy foreign agent  72  first stores the service profile of the mobile node  71  in the relay point option in the option header of the IPv6 packet containing the binding update message, and transmits the packet to the home agent  21 .  
     [0441] (12) The process (9) shown in FIG. 50 is performed. That is, upon receipt of the IPv6 packet containing the binding update message, the home agent  21  performs the home registering process for the mobile node  71 , obtains the service profile of the mobile node  71 , and returns the binding acknowledge message to the mobile node  71 .  
     [0442] (13) The process (10) shown in FIG. 50 is performed. That is, the communications node  42  transmits the data packet to the mobile node  71 . The packet is encapsulated into an IPv6 tunnel packet by the home agent  21 , and is transferred to the mobile node  71 .  
     [0443] (14) Upon receipt of the IPv6 tunnel packet, the mobile node  71  performs the process in step S 304  of the flowchart shown in FIG. 41. That is, the mobile node  71  transmits the binding update message to the communications node  42 .  
     [0444] (15) Upon receipt of the packet containing the binding update message, the proxy foreign agent  72  performs the processes in steps S 344  through S 346  of the flowchart shown in FIG. 42 as in the process (11) above. That is, the proxy foreign agent  72  first stores the service profile of the mobile node  71  in the relay point option in the option header of the IPv6 packet containing the binding update message, and transmits the packet to the communications node  42 .  
     [0445] (16) Upon receipt of the IPv6 packet containing the binding update message, the communications node  42  generates or updates binding cache according to the binding update message as in the process (12) shown in FIG. 50, and obtains the service profile.  
     [0446] Thus, when the proxy foreign agent  72  is provided, the service profile is not distributed to the mobile node  71 . When the mobile node  71  transmits a binding update message to the home agent  21  and the communications node  42 , the service profile is transferred from the proxy foreign agent  72  to the home agent  21  and the communications node  42 , respectively.  
     [0447] 7.3 Sequence of using an FDR message and an FDA message in the system according to the fourth embodiment  
     [0448] The sequence is basically the same as the sequence according to the fourth embodiment shown in FIG. 51. In this sequence, an FDR message and an FDA message are used between the DHCP server  63  and the proxy foreign agent  72 . These messages are newly introduced in the present invention. The sequence is described below by referring to FIG. 52.  
     [0449] (1) and (2) are the same as the processes (1) and (2) shown in FIG. 51.  
     [0450] (3) Upon receipt of the packet containing the DHCP request message, the DHCP server  63  performs the processes in steps S 373 , S 374 , and S 392  of the flowchart shown in FIG. 45. That is, the DHCP server  63  generates an FDR message containing the DHCP request message, and transmits the message to the proxy foreign agent  72 . The FDR message has the format shown in FIG. 77C, and is stored in the UDP packet.  
     [0451] (4) Upon receipt of the FDR message containing the DHCP request message, the proxy foreign agent  72  performs the processes in steps S 364  through S 367  of the flowchart shown in FIG. 43. That is, the proxy foreign agent  72  generates an AMR message containing the DHCP request message, and transmits the message to the AAAF server  32 . The format of the AMR message is shown in FIG. 77A.  
     [0452] (5) through (7) are the same as the processes (5) through (7) shown in FIG. 51. That is, the AMR message is transferred from the AAAF server  32  to the AAAH server  22 , the AMA message is returned from the AAAH server  22  to the AAAF server  32 , and the AMA message is transferred from the AAAF server  32  to the proxy foreign agent  72 . At this time, the AMA message stores the service profile of the mobile node  71 .  
     [0453] (8) Upon receipt of the packet containing the AMA message, the proxy foreign agent  72  performs the processes in steps S 362  and S 363  of the flowchart shown in FIG. 43. That is, the proxy foreign agent  72  first obtains the service profile of the mobile node  71  from the received packet, and stores it in the service profile cache. Then, it generates an FDA message according to the received AMA message. The format of the FDA message is shown in FIG. 77D. The FDA message stored the DHCP reply message. The proxy foreign agent  72  transmits the packet containing the FDA message to the DHCP server  63 .  
     [0454] (9) Upon receipt of the packet containing the FDA message, the DHCP server  63  performs the process in step S 391  of the flowchart shown in FIG. 45. That is, the DHCP server  63  generates a DHCP reply message, and transmits it to the mobile node  61 .  
     [0455] (10) through (16) are the same as the corresponding processes shown in FIG. 51  
     [0456] 8. Fifth and Sixth Embodiment  
     [0457] 8.1 Fifth embodiment  
     [0458]FIG. 53 shows the configuration of the network of the communications service providing system according to the fifth embodiment of the present invention. The system according to the fifth embodiment is designed based on the system according to the third embodiment. However, a router device  81  used in the system according to the fifth embodiment is provided not only with the routing function specific to a common router device, but also with the DHCP server function.  
     [0459]FIG. 54 shows the configuration of the main devices of the communications service providing system according to the fifth embodiment. The home agent  21 , the AAAH server  22 , the AAAF server  32 , the communications node  42 , and the mobile node  61  are the same as the corresponding devices in the system according to the third embodiment.  
     [0460] The router device  81  comprises a packet control unit, a protocol control unit, and a transfer control unit. The protocol control unit is provided with a DIAMETER client function (DCF), and a DHCP server function. The DHCP server function dynamically assigns an address at a DHCP request from a terminal (including the mobile node  61 ).  
     [0461]FIG. 55 is a flowchart of the operations of the router device according to the fifth embodiment of the present invention. The flowchart shows the operation performed after the router device  81  receives a packet.  
     [0462] In step S 501 , the type of message stored in the received packet is checked. If a DHCP request message is received, then a session transaction is searched for using the user NAI of the mobile node in steps S 502  and S 503 . If a corresponding session transaction is not detected, it is generated. Then, in step S 504 , an AMR message containing a DHCP message is generated, and the message is transmitted to the AAAF server  32 . The format of the AMR message is shown in FIG. 77A. The AMR message is stored in the UDP packet.  
     [0463] If an AMA message is received, a DHCP reply message is generated and transmitted to the mobile node  61  in step S 505 . The format of the DHCP reply message is shown in FIGS. 72A through 72C. Its extension area stores the service profile of the mobile node  61 . The DHCP reply message is stored in the UDP packet. If the DHCP request message or the AMA message is not received, a corresponding process is performed in step S 511 .  
     [0464] As described above, upon receipt of the DHCP request message, the router device  81  generates an AMR message and transmits it to the AAAF server  32 . On the other hand, upon receipt of the AMA message, it generates the DHCP reply message and transmits it to the mobile node  61 .  
     [0465]FIG. 56 shows the sequence of the DHCP-AAA cooperation according to the fifth embodiment of the present invention.  
     [0466] (1) The router device  81  transmits an ICMP router advertisement message.  
     [0467] (2) Upon receipt of the advertisement message, the mobile node  61  transmits the DHCP request message to the DHCP server as in the process (2) shown in FIG. 50. However, in the system according to the fifth embodiment, the router device  81  is provided with the DHCP server function. Therefore, the mobile node  61  transmits the DHCP request message to the router device  81 .  
     [0468] (3) Upon receipt of the packet containing the DHCP request message, the router device  81  performs the processes in steps S 502  through S 504  of the flowchart shown in FIG. 55. That is, the router device  81  generates an AMR message shown in FIG. 77A and transmits it to the AAAF server  32 .  
     [0469] (4) through (6) are the same as the processes (4) through (6) shown in FIG. 50. That is, the AMR message is transmitted from the AAAF server  32  to the AAAH server  22 , the AMA message is returned from the AAAH server  22  to the AAAF server  32 , and the AMA message is transferred from the AAAF server  32  to the DHCP server. However, in the system according to the fifth embodiment, the router device  81  is provided with the DHCP server function. Therefore, the AAAF server  32  transfers the AMA message to the router device  81 . The AMA message contains the service profile of the mobile node  61 .  
     [0470] (7) Upon receipt of the packet containing the AMA message, the router device  81  performs the process in step S 505  of the flowchart shown in FIG. 55. That is, the router device  81  generates a DHCP reply message shown in FIG. 72 and transmits it to the mobile node  61 .  
     [0471] (8) through (12) are the same as the processes (8) through (12) shown in FIG. 50.  
     [0472] 8.2 Sixth embodiment  
     [0473]FIG. 57 shows the configuration of the network of the communications service providing system according to the sixth embodiment of the present invention. The system according to the sixth embodiment is designed based on the system according to the fourth embodiment. However, a proxy foreign agent  82  used in the system according to the sixth embodiment is provided with the DHCP server function.  
     [0474]FIG. 58 shows the configuration of the main devices of the communications service providing system according to the sixth embodiment. The home agent  21 , the AAAH server  22 , the AAAF server  32 , the communications node  42 , and the mobile node  71  are the same as the corresponding devices in the system according to the fourth embodiment.  
     [0475] The proxy foreign agent  82  comprises a packet control unit, a protocol control unit, a transfer control unit, a service control unit, and a service profile cache (SPC). The protocol control unit is provided with a DIAMETER client function (DCF), and a DHCP server function. The DHCP server function dynamically assigns an address at a DHCP request from a terminal (including the mobile node  71 ).  
     [0476]FIGS. 59 and 60 are flowcharts of the operations of the proxy foreign agent according to the sixth embodiment. The flowcharts show the operations performed after the proxy foreign agent  82  receives a packet.  
     [0477] In steps S 521  and S 522 , a received packet is filtered using a source address and a destination address. When the source of the received packet is the mobile node  71 , the processes in and after step S 523  are performed. When the destination of the received packet is the proxy foreign agent  82 , the processes in and after step S 531  are performed. In the case other than the above mentioned two cases, the received packet is processed based on the service profile provided for the proxy foreign agent  82 , and is then transferred in steps S 528  and S 529 .  
     [0478] In step S 523 , the type of message stored in the received packet is checked. If the binding update message is received, the processes in and after step S 524  are performed. Otherwise, the received packet is transferred according to the destination address in step S 527 .  
     [0479] In step S 524 , a session transaction is searched for using the IP address of the mobile node  71 . Thus, the service profile of the mobile node  71  is extracted. Then, in step S 525 , the service profile extracted in step S 524  is added to the relay point option in the option header of the IPv6 packet. Furthermore, in step S 526 , the binding update message is added to the option header. Then, the IPv6 packet with that option header is transferred to the destination (the home agent  21  or the communications node  42 ).  
     [0480] In step S 531 , the type of message stored in the received packet is checked. When the DHCP request message is received, the processes in and after step S 532  are performed. When the AMA message is received, the processes in and after step S 535  are performed. If these messages are not received, a corresponding process is performed in step S 541 .  
     [0481] In steps S 532  and S 533 , a session transaction is searched for using the user NAI of the mobile node. If a corresponding session transaction is not detected, it is generated. Then, in step S 534 , an AMR message containing the DHCP request message is generated, and is transmitted to the AAAF server  32 . The format of the AMR message is shown in FIG. 77A.  
     [0482] In step S 535 , the service profile of the mobile node  71  received together with the AMA message is obtained. The service profile is stored in the service profile cache provided for the proxy foreign agent  82 . Then, in step S 536 , the DHCP reply message corresponding to the received AMA message is generated, and the message is transmitted to the mobile node  71 . The format of the DHCP reply message is shown in FIGS. 72A through 72C, and includes the service profile of the mobile node  71 .  
     [0483] As described above, upon receipt of the binding update message, the proxy foreign agent  82  transmits the message together with the service profile of the mobile node  71  to the home agent  21  or the communications node  42 . Upon receipt of the AMA message, it obtains the service profile of the mobile node  71 , and transmits the DHCP reply message to the mobile node  71 . Upon receipt of the DHCP request message, the proxy foreign agent  82  generates an AMR message and transmits it to the AAAF server  32 .  
     [0484]FIG. 61 shows the sequence of the DHCP-AAA cooperation according to the sixth embodiment of the present invention.  
     [0485] (1) The proxy foreign agent  82  transmits the ICMP router advertisement message.  
     [0486] (2) Upon receipt of the advertisement message, the mobile node  71  transmits the DHCP request message to the DHCP server. However, in the system according to the sixth embodiment, the proxy foreign agent  82  is provided with the DHCP server function. Therefore, the mobile node  71  transmits the DHCP request message to the proxy foreign agent  82 .  
     [0487] (3) Upon receipt of a packet containing the DHCP request message, the proxy foreign agent  82  performs the processes in steps S 532  through S 534  of the flowchart shown in FIG. 60. That is, the proxy foreign agent  82  generates an AMR message shown in FIG. 77A and transmits it to the AAAF server  32 .  
     [0488] (4) through (6) are the same as the corresponding processes (4) through (6) shown in FIG. 50. That is, the AMR message is transmitted from the AAAF server  32  to the AAAH server  22 , the AMA message is returned from the AAAH server  22  to the AAAF server  32 , and the AMA message is transferred from the AAAF server  32  to the DHCP server. However, in the system according to the sixth embodiment, the proxy foreign agent  82  is provided with the DHCP server function. Therefore, the AAAF server  32  transmits the AMA message to the proxy foreign agent  82 . The AMA message contains the service profile of the mobile node  71 .  
     [0489] (7) Upon receipt of the packet containing the AMA message, the proxy foreign agent  82  performs the processes in steps S 535  and S 536  of the flowchart shown in shown in FIG. 60. That is, the proxy foreign agent  82  first obtains the service profile of the mobile node  71  received together with the AMA message. Then, the DHCP reply message shown in FIG. 72 is generated and transmitted to the mobile node  71 .  
     [0490] (8) through (14) are the same as the corresponding processes (10) through (16) shown in FIG. 51.  
     [0491] In the system according to the present invention, the service control information for a mobile node is distributed to the mobile node in the procedure of authenticating the mobile node and registering the location of the mobile node. At this time, the information relating to the authentication and the location registration of the mobile node is stored in the header of a packet and transmitted. Therefore, in a network in which the IP payload of each packet is encrypted, each communications appliance can obtain the information relating to the location registration of the mobile node without decryption process and perform a corresponding process. Therefore, in a network supporting the IPv6, each communications appliance can distribute the authentication information and the location registration information of a mobile node, and the service control information.  
     [0492] Furthermore, a function equivalent to a foreign agent defined in the mobile IPv4 is provided in the router device accommodating a mobile node, and the router device provides a communications service according to the service control information, thereby reducing the load of the mobile node.  
     [0493] Additionally, since the address inquiring process is performed in cooperation with the mobile node authenticating process, the service control information for the mobile node is distributed to the mobile node in the procedure that the mobile node obtains an address from the address server.  
     [0494] Furthermore, since messages for interfacing an address inquiry process and an authenticating process about the mobile node are used, a configuration of the address server is simplified and a load of the address server is reduced.