KR100667699B1 - DHC relay device and method thereof of portable internet system, and packet connection router including the device - Google Patents

Abstract

The present invention relates to a DHCP relay device and a method of the portable Internet system, and to a packet access router including the device, in particular, the DHCP relay device performs authorization verification for a request message related to DHCP address allocation / release of a mobile terminal. Afterwards, it sends a request message about DHCP address allocation / release to the DHCP server. After address assignment is made to the mobile station, DNS registration and renewal of the domain name of the service subscriber and the newly assigned IP address is performed. According to the present invention, a request for registration / release of a DHCP address of a mobile terminal in a DHCP relay device operating in a PAR of a mobile Internet system for a mobile terminal using a DHCP service in a portable Internet system capable of providing both DHCP and MIP services By performing the terminal authority verification on the message and transmitting it to the DHCP server, it is possible to prevent the allocation of address resources to unauthorized users, that is, illegal users.

Mobile Internet, Terminal, DHCP Message, Relay, DNS, Authorization Verification

Description

DCP relay device and method thereof of a portable Internet system, and a packet connection router including the device {APPARATUS AND METHOD FOR DHCP RELAY IN PORTABLE INTERNET SYSTEM AND PACKET CCESS ROUTER HAVING THE APPARATUS}

1 is a view showing the structure of a portable Internet system according to an embodiment of the present invention.

2 is a diagram showing the configuration of a DHCP relay device of a portable Internet system according to an embodiment of the present invention.

3 is a diagram illustrating a DHCP address allocation process of a mobile terminal in a portable internet system according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a DHCP address release process of a mobile terminal in a portable Internet system according to an embodiment of the present invention.

5 is a diagram illustrating a DHCP address release process of a mobile terminal by an AP in a portable Internet system according to an embodiment of the present invention.

6 is a diagram illustrating a DHCP address release process of a mobile terminal by a PAR in a portable Internet system according to an embodiment of the present invention.

7A to 7D are diagrams illustrating a message processing procedure in the DHCP relay apparatus of the portable Internet system according to an embodiment of the present invention, respectively.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable Internet system, and more particularly, to a user of a mobile terminal that wants to access the Internet for efficient use of an IP address, a Dynamic IP Configuration Protocol (DHCP) service function and a mobile IP for a user who can move between IP subnets The present invention relates to a DHCP relay device of a portable Internet system capable of providing both service functions, a method thereof, and a packet access router including the device.

Recently, the domestic high-speed Internet service and mobile communication service market is gradually entering a saturation state, and the global mobile communication market is continuing to slump due to delayed commercialization of 3G mobile service. In this stagnant telecommunications market environment, wireless Internet services that provide high-speed Internet access to mobile subscribers at low rates are considered a breakthrough in creating new markets.

In general, the wireless Internet technology may be classified into commercial wireless LAN, cellular based mobile communication such as cdma 2000 1xEV-DO, and portable Internet to be commercialized in the future.

Wireless LAN is capable of Internet service at high transmission speed but limited in mobility and service area. Cellular-based mobile communication supports broadband service area and high speed mobility but is limited in transmission speed and usage fee. Therefore, existing wireless LAN and cellular based mobile communication systems cannot provide high-speed data services at low rates to mobile subscribers.

On the other hand, the mobile Internet is located in the middle of the wireless LAN and the mobile communication-based wireless Internet, and is a service that combines the advantages of both services. Various wireless data services including video and high speed packet data may be provided. As such, the portable Internet is in the spotlight as a next generation communication method because it supports a wide range of service areas, high transmission speeds, and mobility. Currently, various standards have been proposed for the portable Internet, and international standardization of the portable internet is currently underway based on IEEE 802.16.

The wireless packet data system must have an IP address for identifying the mobile terminal in order to receive the packet call service through the packet network. Preferably, all mobile terminals must have unique IP addresses, but since the number of available IP addresses is limited, a method of temporarily allocating an IP address only when the mobile terminal uses a service is mainly used.

In general, in a wireless network providing a DHCP service, a DHCP server allocates a dynamic IP address of a mobile terminal, and in a wireless network providing a MIP service, a HA (Home Agent) allocates a dynamic IP address of a mobile terminal.

DHCP is a protocol that allows network administrators to centrally manage and assign IP addresses on networks within an organization. Network administrators centrally manage and assign IP addresses and automatically create new network addresses when computers connect to other locations on the network. Allows you to send an IP address. In addition, MIP is a protocol for the continuous use of IP addresses of mobile users. The MIP detects the movement of the mobile terminal and enables the network to communicate in the same manner as before the mobile network. You can use the Internet with your existing IP address outside of your home network.

Applying the prior art to a portable Internet system capable of providing both DHCP and MIP service, the MIP service user is always assigned an address only for the authenticated user because the HA is assigned an address during the MIP registration procedure of the mobile terminal. . Thus, no waste of address resources for illegal users occurs. However, since the mobile station requests a dynamic address assignment directly to the DHCP server for the DHCP service user, the DHCP server cannot know whether the mobile terminal has been authenticated unless it is linked with the AAA server. Therefore, a problem arises in that dynamic addresses can only be allocated to illegal users through hacking or the like.

As a related art, Korean Patent Laid-Open Publication No. 2003-22534 discloses a system and a method for preventing unauthorized access to the Internet and a network using DHCP. This technique configures a DHCP protecting server between the authentication DB and the DHCP server so that the DHCP server does not directly assign addresses to DHCP clients. After receiving the message from the DHCP client, the DHCP server sends this message to the DHCP protecting server to compare the hardware address of the authentication DB with the hardware address of the DHCP message, and prohibit address assignment to unauthenticated DHCP clients. . However, this technique has the effect of preventing internet access for unauthorized users, but there is a problem that an entity called a DHCP protecting server must be added.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a DHCP relay device and method thereof in a portable Internet system capable of preventing address resource allocation to an illegal user without adding an entity, and a packet access router including the device. .

In order to solve the above problems, the DHCP relay device of the portable Internet system according to an aspect of the present invention,

A DHCP relay device that processes a Dynamic Host Configuration Protocol (DHCP) message sent and received by a packet access router (PAR) that performs a packet access routing function in a portable Internet system.

A DHCP relay interface unit providing an interface for processing the DHCP message; A domain name / address mapping manager for updating DNS (Domain Name Server) information of the mobile terminal according to address allocation / release of the mobile terminal connected to the portable Internet system; A data access request processing unit for retrieving session information for the mobile terminal from a session information database in which session information for the mobile terminal is stored for updating the DNS information of the mobile terminal and verifying authority; And verifying the authority of the mobile terminal through the data access request processing unit with respect to the DHCP message transmitted from the mobile terminal through the DHCP relay interface unit, and assigning an address of the mobile terminal through the domain name / address mapping manager. DHCP message processing unit for updating the DNS information of the mobile terminal upon release.

In this case, the DHCP message processing unit adds and transmits a DHCP Subnet Selection Option to an option field of a DHCP message received from the mobile terminal when the authority verification of the mobile terminal is successful.

According to another aspect of the present invention, a packet access router includes

A packet access router for processing a DHCP (Dynamic Host Configuration Protocol) message according to an address assignment or release for a mobile terminal in a portable Internet system,

A session information database in which session information for a mobile terminal is stored; And DHCP for retrieving the session information database, performing authority verification on the DHCP message transmitted from the mobile terminal, and updating DNS (Domain Name Server) information for the mobile terminal when allocating or releasing an address for the mobile terminal. It includes a relay unit.

DHCP relay method according to another aspect of the present invention,

A DHCP (Dynamic Host Configuration Protocol) relay method for processing messages transmitted and received by a packet access router (PAR) that performs a packet access routing function in a portable Internet system.

a) receiving and processing a DHCP message transmitted / received to the PAR, wherein the DHCP message is a DHCP address allocation / release message related to the terminal; And b) performing authority verification of the mobile terminal with respect to the DHCP message transmitted from the mobile terminal among the DHCP messages.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

A DHCP service providing method in a portable Internet system of a portable Internet system according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

First, the portable Internet system to which the present invention is applied will be described in detail with reference to FIG. 1.

1 is a view showing the structure of a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 1, the portable Internet system 100 according to an embodiment of the present invention includes a terminal 110 (Access Terminal, hereinafter referred to as 'AT') 110, an access point (hereinafter referred to as an 'AP') ( 120, a packet access router (hereinafter referred to as a 'PAR') 130, an AAA (Authentication, Authorization and Accounting; referred to as 'AAA') server 140, a home agent (hereinafter referred to as 'AAA') HA '), 150, Domain Name Server (hereinafter referred to as' DNS Server') 160, and DHCP (Dynamic Host Configuration Protocol; referred to as' DHCP ') server 170, It provides high speed internet service through wireless connection, and can provide both DHCP and MIP service.

The AT 110 is a portable Internet terminal, which has mobility and performs a wireless channel transmission / reception function according to a wireless access standard of the portable Internet system 100 at a frequency of 2.3 GHz in order to access and transmit high-speed packet data by accessing the AP 120. do.

The AP 120 is a device that connects a wireless network and a wired network to control a wireless channel, and is connected to a wired network to provide a wireless packet data service directly to the AT 110. That is, the AP 120 performs initial access, intersectoral handover control, and quality of service (QoS) control between the ATs 110 and receives a radio signal from the AT 110 to the PAR 130. On the contrary, it converts various information received from the PAR 130 into a radio signal and transmits the information to the AT 110.

The PAR 130 is connected to a plurality of APs 120 by IP-based wired connection with an IP-based service provider IP network 200 constituting the public Internet network 300, and has a packet access routing function and a foreign agent of a MIP. : FA) Perform the function. In addition, the PAR 130 interworks with the AAA server 140 for HA 150 and user authentication for IP mobility, and one PAR area becomes one IP subnet. Here, the external agent function refers to a user registration and deregistration function so that a packet-based internet access and roaming service can be moved to another service network while maintaining an internet connection.

In addition, according to an embodiment of the present invention, the DHCP relay device 132 is mounted on the PAR 130. The DHCP relay device 132 performs an authority verification function for the DHCP address allocation / release request message of the AT 110 and a DNS function for the subscriber's domain name and the newly allocated IP address.

The AAA server 140 is connected to the PAR 130 and the operator IP network to authenticate the AT 110 and the user, verify service authority, generate an authentication key, and charge the user to provide DHCP and MIP services to the subscribers of the mobile Internet network. Perform the function. In addition, the AAA server 150 uses a diameter protocol that is being standardized by the Internet Engineer Task Force (IETF). Diameter protocol enables authentication, authorization and billing information transfer by inter-server interworking.

The HA 150 is connected through the PAR 130 and the Internet network 300 to perform a MIP service function.

The DNS server 160 maps and manages the domain name and the IP address of the AT 110, and functions to interpret and inform the domain name or the IP address.

The DHCP server 170 manages IP address resources that can be operated in the portable Internet network for each subnet and allocates address resources of the corresponding subnet according to the dynamic address allocation request of the AT 110.

The portable Internet system 100 shown in FIG. 1 promoted by IEEE 802.16 may interwork with other Internet networks through the AAA server 150, and may configure one or more PARs 130 on the same network. In addition, one or more APs 120 may be configured under one PAR 130, and a plurality of ATs 110 may be connected to one AP 120 to receive a service. In addition, even when the AT 110 moves from a cell governed by the AP 120 to a new cell, the AT 110 may receive a service provided by an existing cell.

2 is a diagram showing the configuration of a DHCP relay device of a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 2, the PAR 130 of the portable Internet system according to the embodiment of the present invention includes a DHCP relay device 132 and a session information database 134.

 The DHCP relay device 132 includes a DHCP relay interface unit 132-1, a DHCP message processing unit 132-2, a domain name / address mapping management unit 132-3, and a data access request processing unit 132-4. And relays the DHCP message allocation / release request message of the AT 110 to the DHCP server 170, and after the address assignment is made to the AT 110, the user's domain name and the newly assigned IP address. The DNS registration is performed to dynamically update the DNS server 160.

The DHCP relay interface unit 132-1 provides an interface for transmitting and receiving messages with the AP 120, the DHCP server 170, and the DNS server 160. At this time, the interface with the AP 120 for transmitting and receiving the DHCP message of the AT (110) does not use a well known port (well know port), the dedicated interface for communication between the AP (120) -PAR (130) use.

The DHCP message processing unit 132-2 performs a relay function to receive and process a dynamic address allocation / release request message for the AT 110 of the DHCP service user in cooperation with the DHCP server 170. In addition, the DHCP message processing unit 132-2 searches the session information database 134 of the PAR 130 through the data access request processing unit 132-4 to determine whether the AT 110 that requested IP address allocation / release is authenticated. It performs the authority verification function to verify, and performs a function of requesting to register the domain name and IP address of the AT (110) to the DNS server 160 through the domain name / address mapping management unit (132-3).

The domain name / address mapping manager 132-3 manages the connection between the domain name and the IP address of the AT 110 in association with the DNS server 160. That is, the domain name / address mapping management unit 132-3 searches for the session information database 134 through the data access request processing unit 132-4 when the IP address is allocated / released to the AT 110. Acquire a domain name of the) to register / delete the domain name and IP address of the AT (110) to the DNS server 160.

The data access request processor 132-4 retrieves information stored in the session information database 134 to perform data request processing functions of the DHCP message processor 132-2 and the domain name / address mapping manager 132-3. .

The session information database 134 stores and manages session information for the AT 110 currently connected to the portable Internet network. When the AT 110 performs an authentication and registration function, the AAA server 140 Obtain session information of the AT (110) from. The session information of the AT 110 may be used to obtain information such as whether the AT 110 is authenticated or what is the domain name of the AT 110.

Next, a process of allocating a DHCP address to the AT 110 in the portable Internet system will be described in detail with reference to FIG. 3.

3 is a diagram illustrating a DHCP address allocation process of a mobile terminal in a portable internet system according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the AT 110 performs a user authentication and registration function to receive a DHCP service. Then, in order to receive a new IP address, a DHCPDISCOVER message for searching for a DHCP server 170 is transmitted to the PAR 130 (S302). Then, the DHCP relay device 132 of the PAR 130 receives it.

Upon receiving the DHCPDISCOVER message transmitted by the AT 110 to find the DHCP server 170, the DHCP relay device 132 performs an authority verification function to determine whether the AT 110 is authenticated and legal (S304). This function is performed by searching the session information database 134 managed by the PAR 130 with the hardware address of the AT 110 included in the DHCPDISCOVER message.

As a result of the authority verification, if the IP address allocation request is made by the legitimate AT 110, a DHCP Subnet Selection Option is added to the DHCPDISCOVER message and transmitted to the DHCP server 170 (S306). After receiving the DHCPOFFER message from the DHCP server 170 as a result of the DHCPDISCOVER message, the DHCP relay device 132 transmits a DISOFFER message to the AT 110 after checking whether it is a response to the previously sent DHCPDISCOVER message (S308-S310). ).

Upon receiving the DISOFFER message, the AT 110 transmits a DHCPREQUEST message to the DHCP relay device 132 in order to request an address assignment (S312). After receiving the DHCPREQUEST message, the DHCP relay device 132 transmits the DHCPREQUEST message to the DHCP server 170 after performing authorization verification of the AT 110 (S314).

The DHCP server 170 allocates a dynamic IP address belonging to the subnet of the PAR 130 region to which the AT 110 is connected, and transmits a DHCPACK message including the result to the DHCP relay device 132 (S318). Upon receiving the DHCPACK message, the DHCP relay device 132 performs a dynamic DNS update on the domain name and the assigned IP address for the AT 110 (S320).

 When the DNS update is successfully completed, the DHCP relay device 132 transmits a DHCPACK message to the AT 110 to allow the AT 110 to receive a DHCP service (S322).

On the other hand, if the address allocation for the AT 110 fails, the DHCP server 170 transmits a DHCPNAK message to the DHCP relay device 132, the DHCP relay device 132 sends a DHCPNAK message back to the AT (110) do.

Next, a process of releasing the DHCP address of the AT 110 in the portable Internet system will be described in detail with reference to FIGS. 4 to 6.

4 is a diagram illustrating a DHCP address release process of a mobile terminal in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 4, the AT 110 transmits a DHCPRELEASE message to the PAR 130 in order to terminate the portable Internet connection (S402). Then, the DHCP relay device 132 of the PAR 130 receives this.

Upon receiving the DHCPRELEASE message, the DHCP relay device 132 performs the authority verification function of the AT 110 to determine whether the AT 110 requests the release of a legally assigned address (S404). If the authorization verification result indicates that the IP address release request by the legitimate AT 110, the DHCP relay device 132 is the domain name and IP of the AT 110 registered in the DNS server 160 when the AT 110 is assigned an IP address Dynamic DNS updating is performed to delete the address information (S406). In addition, the DHCP relay device 132 adds a DHCP subnet selection option to the DHCPRELEASE message and transmits it to the DHCP server 170 (S408).

5 is a diagram illustrating a DHCP address release process of a mobile terminal by an AP in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 5, when the wireless channel between the AT 110 and the AP 120 is abnormally released, the AP 120 sends a DREGreq message to the PAR 130 to terminate the service for the AT 110. It transmits (S502). Then, the DHCP relay device 132 of the PAR 130 receives this.

The DHCP relay device 132 obtains session information about the AT 110 from the session information database 134 to release an IP address assigned to the AT 110 and generates a DHCPRELEASE message (S504). When the AT 110 receives an IP address, the DHCP relay device 132 performs dynamic DNS update to delete domain name and IP address information of the AT 110 registered in the DNS server 160 (S506). ). Then, the DHCP relay device 132 transmits a DHCPRELEASE message to the DHCP server 170 (S508), and transmits a DREGrsp message to the AP 120 (S510).

6 is a diagram illustrating a DHCP address release process of a mobile terminal by a PAR in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 6, the AT 110 recognizes when the timer for Leasetime expires without extension / release for the assigned address (S602), and the DHCP relay device 132 of the PAR 130 recognizes AT ( When 110 is assigned an IP address, after performing a dynamic DNS update to delete the domain name and IP address information of the AT 110 registered in the DNS server 160 (S604), the service for the AT (110) In order to release the DREGreq message to the AP 120 (S606).

Lastly, a process of processing a message received from the AT 110, the AP 120, the DNS server 160 and the DHCP server 170 by the DHCP relay device of the portable Internet system according to an embodiment of the present invention. It will be described in detail with reference to 7a to 7d.

7A to 7D are diagrams illustrating a process of processing a received message by a DHCP relay device of a portable Internet system according to an embodiment of the present invention, respectively.

First, as shown in FIG. 7A, when the DHCP relay device 132 of the PAR 130 receives a DHCPDISCOVER, DHCPREQUEST, and DHCPRELEASE message (hereinafter, collectively referred to as a 'first DHCP message') from the AT 110 (S701). In order to confirm whether the AT 110 is authenticated and a legitimate user through the session information database 134, authority verification of the AT 110 is performed (S702). At this time, if the authority verification of the AT 110 fails, the DHCP relay device 132 determines that it is an illegal user and discards the message received from the AT 110 (S703-S704). On the contrary, if the authority verification of the AT 110 succeeds, the DHCP relay device 132 selects the DHCP subnet in the option field of the DHCP message to receive an address for the subnet of the corresponding PAR 130 from the DHCP server 170. The option is added (S705). In addition, the DHCP relay device 132 determines whether the received message is a DHCPRELEASE message (S706). If the DHCPRELEASE message is received, the domain name and IP address information of the AT 110 registered in the DNS server 160 when the IP address was previously assigned. Dynamic DNS updating is performed to delete the data (S707). The first DHCP message thus processed is transmitted to the DHCP server 170 (S708).

Next, as shown in FIG. 7B, when the DHCP relay device 132 of the PAR 130 receives a DHCPOFFER or DHCPACK message from the DHCP server 170 (S711), it responds to a previously transmitted DHCPDISCOVER or DHCPREQUEST message. Check whether the message (S712). At this time, if it is not a response message to the previously transmitted DHCP message, the received message is discarded (S713).

The DHCP relay device 132 checks whether the received message is a DHCPACK message (S714). At this time, if the received message is a DHCPACK message, the DHCP relay device 132 sets a timer for the Leasetime allocated from the DHCP server 170 (S715). This is used by the AT 110 to release the service for the AT 110 when Leasetime expires without extension / release for the assigned IP address. The DHCP relay device 132 performs dynamic DNS updating by registering the domain name and the newly assigned address for the AT 110 with the DNS server 160 (S716). This allows a communication station (mobile station) that wants to transmit packet data to the AT 110 to transmit the packet data to the AT 110 through a DNS query. The DHCP relay device 132 thus processed transmits a DHCPOFFER or DHCPACK message to the AT 110 (S718).

Next, as shown in FIG. 7C, when the wireless channel between the AT 110 and the AP 120 is abnormally terminated, the DHCP relay device 132 may release the service for the AT 110. When receiving a DREGreq message from the (721), the session information for the AT 110 is collected through the session information database 134 to generate a DHCPRELEASE message (S722). In addition, the DHCP relay device 132 releases the timer for the leasetime set in the AT 110 (S723), and when the AT 110 is assigned an IP address, the domain of the AT 110 registered in the DNS server 160. Dynamic DNS updating is performed to delete the name and IP address information (S724). Thereafter, the DHCP relay device 132 transmits a DHCPRELEASE message to the DHCP server 170 (S725), and transmits a DREGrsp message to the AP 120 (S726).

In addition, the DHCP relay device 132 is the DNS server 170 when the AT 110 is assigned an IP address when the timer for Leasetime expires (S731) without the extension / release of the address assigned by the AT (110). In order to delete the domain name and IP address information of the AT (110) registered in the (S732), and performs a dynamic DNS update (S732), and transmits a DREGreq message to the AP (120) to release the service for the AT (110) S733).

As described above, the DHCP relay device 132 of the portable Internet system according to an embodiment of the present invention is mounted on the PAR 130 performing a packet access routing function to directly connect the session information database 134 of the PAR 130. By retrieving and determining whether the mobile terminal is authenticated, it supports IP address allocation and supports updating of DNS server when IP address is assigned. By doing so, it is possible to prohibit Internet access for illegal users without additional entities, and additionally, the DNS can be renewed so that a mobile station that wants to communicate with the mobile terminal performs a DNS lookup to enable communication with the mobile terminal.

The above embodiments are intended to illustrate the present invention, the scope of the present invention is not limited to the embodiments, it can be modified or modified by those skilled in the art within the scope of the invention defined by the appended claims.

According to the present invention, a request for registration / release of a DHCP address of a mobile terminal in a DHCP relay device operating in a PAR of a mobile Internet system for a mobile terminal using a DHCP service in a portable Internet system capable of providing both DHCP and MIP services By performing the terminal authority verification on the message and transmitting it to the DHCP server, it is possible to prevent the allocation of address resources to unauthorized users, that is, illegal users.

In addition, it is possible to update the DNS so that a mobile station that wants to communicate with the mobile terminal performs a DNS search, thereby enabling communication with the mobile terminal.

Claims (16)

In a DHCP relay device for processing a Dynamic Host Configuration Protocol (DHCP) message transmitted and received by a packet access router (PAR) that performs a packet access routing function in a portable Internet system, A DHCP relay interface unit providing an interface for processing the DHCP message; A domain name / address mapping manager for updating DNS (Domain Name Server) information of the mobile terminal according to address allocation / release of the mobile terminal connected to the portable Internet system; A data access request processing unit for retrieving session information for the mobile terminal from a session information database in which session information for the mobile terminal is stored for updating the DNS information of the mobile terminal and verifying authority; And The authority verification of the mobile terminal is performed through the data access request processing unit on the DHCP message transmitted from the mobile terminal through the DHCP relay interface unit, and the address assignment / release of the mobile terminal through the domain name / address mapping manager. DHCP message processing unit for updating the DNS information of the mobile terminal according to DHCP relay device of a mobile Internet system comprising a. The method of claim 1, The DHCP message processing unit, the DHCP relay device of the mobile Internet system to add the DHCP Subnet Selection Option to the option field of the DHCP message received from the mobile terminal upon successful verification of the authority for the mobile terminal. . The method of claim 2, Upon abnormal termination of a wireless channel between the mobile station and an access point (AP) performing a base station function, The DHCP message processing unit, the DHCP relay device of the mobile Internet system to collect the session information of the mobile terminal to generate a DHCP address release message to terminate the service of the mobile terminal and request to update the DNS information of the mobile terminal. The method of claim 2, The DHCP message processing unit, the DHCP relay device of the mobile Internet system to recognize the expiration of the lease time for the address of the mobile terminal to terminate the service of the mobile terminal and request to update the DNS information of the mobile terminal. The method of claim 2, And the DNS information comprises a domain name of a mobile terminal and an IP address corresponding to the domain name. The method of claim 2, And the session information is obtained from an AAA (Authentication, Authorization and Accounting) server performing an authentication function for the mobile terminal when registering or authenticating the mobile terminal. The method of claim 6, The session information database is a DHCP relay device of a portable Internet system managed by the PAR. The method according to any one of claims 1 to 7, The DHCP message is a DHCP relay device of a portable Internet system is a DHCP address assignment / release related message for the mobile terminal. The method of claim 8, The DHCP relay device is a DHCP relay device of a portable internet system mounted in the PAR. A packet access router for processing a DHCP (Dynamic Host Configuration Protocol) message according to an address assignment or release for a mobile terminal in a portable Internet system, A session information database in which session information for a mobile terminal is stored; And DHCP relay to search the session information database to verify the authority of the DHCP message transmitted from the mobile station and to update DNS (Domain Name Server) information for the mobile station when the address is allocated or released to the mobile station. part Packet access router comprising a. The method of claim 10, The DHCP relay unit, A DHCP relay interface unit providing an interface for processing the DHCP message; A domain name / address mapping manager for updating DNS information of the mobile terminal according to the address allocation / release of the mobile terminal; A data access request processing unit for retrieving session information for the mobile terminal from a session information database in which session information for the mobile terminal is stored for updating DNS information of the mobile terminal and verifying authority; And The authority verification of the mobile terminal is performed through the data access request processing unit on the DHCP message transmitted from the mobile terminal through the DHCP relay interface unit, and the address assignment / release of the mobile terminal through the domain name / address mapping manager. DHCP message processing unit for updating the DNS information of the mobile terminal according to Packet access router comprising a. In the method of relaying a DHCP (Dynamic Host Configuration Protocol) to process a message sent and received to a packet access router (PAR) performing a packet access routing function in a portable Internet system, a) receiving and processing a DHCP message transmitted / received to the PAR, wherein the DHCP message is a DHCP address allocation / release message related to the terminal; And b) performing authority verification of the mobile station with respect to the DHCP message transmitted from the mobile station among the DHCP messages; DHCP relay method of the mobile Internet system comprising a. The method of claim 12, c) updating the DNS information by registering / deleting DNS information of the mobile terminal after address allocation / release of the mobile terminal by the DHCP message; DHCP relay method of the mobile Internet system further comprising. The method of claim 13, The DHCP relay method of the mobile Internet system to process the DHCP message by adding a DHCP Subnet Selection Option to the option field of the DHCP message, if the authorization verification of the mobile terminal from step b) is successful. The method of claim 14, Upon abnormal termination of a wireless channel between the mobile station and an access point (AP) that performs a base station function, Collecting session information about the mobile station and generating a DHCP address release message to request the AP to release the service for the mobile station; DHCP relay method of the mobile Internet system further comprising. The method of claim 14, Recognizing the expiration of the lease time for the assigned address of the mobile terminal and performing service release for the mobile terminal; DHCP relay method of the mobile Internet system further comprising.

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