KR100657514B1 - Subnet Handover Method for DHC Service Users in Mobile Internet System - Google Patents

Abstract

The present invention relates to a method for providing an inter-subnet handover for a DHCP service user in a portable Internet system. In this method of providing handover, when a DHCP service user initially receives an IP address in a mobile Internet system that can provide both DHCP and MIP services, the subnet selection option is added to the DHCP address request message of the mobile station in the subnet. Relay DHCP messages to the DHCP server. The address of the subnet used as the subnet selection option is then used when providing handover to the mobile terminal. According to the present invention, even when the mobile terminals are handed over between subnets, the DHCP server can continue to allocate the IP address assigned in the previous subnet to the mobile terminal, thereby providing a seamless inter-subnet handover to the DHCP user.

Description

How to provide inter-subnet handover for DHC service users in portable Internet system {INTER SUBNET HANDOVER METHOD FOR DHCP SERVICE USER IN HIGH SPEED PORTABLE INTERNET SYSTEM}

1 is a block diagram of a general portable Internet system to which the present invention is applied.

2 is a flowchart illustrating a procedure for providing a handover between subnets to a DHCP user in a portable Internet system according to an embodiment of the present invention.

3 is a flowchart illustrating a connection release procedure of a DHCP user handed over between subnets in a portable Internet system according to an embodiment of the present invention.

4 is a flowchart illustrating a connection release procedure of a DHCP user handed over between subnets when a DHCP lease time expires in a portable Internet system according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a traffic path change due to handover between subnets of a DHCP user in a portable Internet system according to an embodiment of the present invention.

The present invention relates to a handover in a portable Internet system. More specifically, the present invention relates to a seamless handover between subnets to DHCP service users in a portable Internet system that provides Dynamic Host Configuration Protocol (DHCP) and Mobile IP (MIP) services. It is about how to provide.

As the demand for mobility of users increases and communication technologies develop, various technologies for extending packet-based wired networks using Internet protocols to wireless networks have been developed, and one of these technologies is a portable Internet system.

The portable Internet system overcomes the shortcomings of a wireless LAN system that provides high speed but does not support service coverage and mobility, and to overcome the shortcomings of a cellular mobile communication system that supports wide service coverage and mobility but has a low transmission speed. It can be said that the system provides an intermediate service between the LAN system and the cellular mobile communication system. In other words, the portable Internet system takes advantage of each of the characteristics of the wireless LAN and cellular mobile communication system as much as possible. The mobile Internet system provides a high speed transmission rate and supports a range of services and mobility close to the cellular mobile communication system. Aim to.

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

For example, in a wireless packet network providing a DHCP service, a DHCP server allocates a dynamic IP address of a mobile terminal, and in a wireless packet network providing a MIP service, a HA (Home Agent) allocates a dynamic IP address of a mobile terminal. In addition, if the conventional technology is applied to a portable Internet system capable of providing both DHCP and MIP services, even if a handover between packet access routers whose subnets are changed occurs, the triangular routing method through HA is used. Can provide services without interruption. This technique is described in Korean Laid-Open Patent No. 2003-59684.

However, for a DHCP service user, when a handover between packet access routers occurs, the subnet is changed. Therefore, the existing IP address needs to be replaced with an IP address corresponding to the subnet of the new packet access router. Therefore, there is a problem that seamless handover between subnets cannot be provided for DHCP service users because all previously communicated sessions are lost.

Accordingly, an aspect of the present invention is to provide a method for preventing the IP address of a mobile terminal from being changed even when a mobile terminal of a DHCP service user is handed over between subnets in a portable Internet system.

In addition, another technical problem of the present invention is a method of providing a seamless service to a mobile terminal without loss of data packets by creating a tunnel between an existing packet access router and a new packet access router when a handover between subnets occurs for a DHCP service user. To provide.

Handover providing method according to a feature of the present invention for solving this problem,

A method for providing handover to a mobile terminal using a DHCP service in a first subnet of a portable internet system,

a) adding an option for selecting the first subnet when allocating an IP address for the mobile terminal and providing the DHCP server to a DHCP server; b) when the mobile terminal requests a handover to a second subnet to be handed over according to a handover request from the mobile terminal, in the option of selecting the IP address and the subnet assigned to the mobile terminal in step a). Providing context information including an address of the first subnet used to the second subnet; And c) creating an encapsulation tunnel to the second subnet for sending a packet to be delivered to the mobile terminal to the second subnet upon accepting a handover from the second subnet.

Handover providing method according to another feature of the present invention,

A method for providing a handover by a second subnet to a mobile terminal moving to a second subnet while using a DHCP service in a first subnet of a portable internet system,

a) an IP address of the mobile terminal and an address of the first subnet, together with a handover request from the first subnet, wherein the address of the first subnet is an address used as a subnet selection option transmitted by the first subnet to a DHCP server Receiving context information including the lease time of the IP address; b) creating a decapsulation tunnel to the first subnet for receiving packets from the first subnet to be delivered to the mobile terminal; And c) allowing registration of the mobile terminal to initiate a DHCP service for the mobile terminal in the second subnet.

DETAILED DESCRIPTION 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, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless otherwise stated.

In addition, the term module described herein refers to a unit for processing a specific function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

Referring now to the drawings with respect to the portable Internet system according to an embodiment of the present invention will be described in detail.

1 is a block diagram of a general portable Internet system to which the present invention is applied. The portable Internet system to which the present invention is applied provides a high-speed Internet service through a wireless connection and has a structure capable of providing both DHCP and MIP services.

Specifically, the portable Internet system to which the present invention is applied is, as shown in FIG. 1, a portable access terminal (Access Terminal, hereinafter referred to as AT) 101, a base station access device (Access Point, hereinafter referred to as AP) ( 102, Packet Access Router (hereinafter referred to as PAR) 103, Operator IP Network 104, AAA (Authentication, Authorization, Accounting) Server 105, Home Agent (HA) 106, DNS Server 107, DHCP server 108, and the Internet 109.

The AT 101 is a mobile terminal and is connected to an AP 102, which is a base station apparatus, with a wireless channel to provide a wireless packet data service.

The AP 102 is a device for connecting a wired network and a wireless network. The AP 102 controls a wireless channel and is connected to a wired network to provide a wireless packet data service directly to the AT 101.

The PAR 103 performs a service access control function, a handover function, a packet access routing function, and a foreign agent function of the MIP, and works with the HA 106 in association with the AAA server 105 for mobility of the MIP. Authenticate the user.

In addition, the PAR 103 is equipped with a DHCP relay that supports the subnet selection option addition function in the DHCP address assignment request message of the AT 101 receiving the DHCP service. In general, one PAR area becomes one IP subnet, and is connected to the operator IP network 104 to have an integrated connection to the Internet 109.

The IP network 106 for each portable Internet service provider includes an AAA server 105, an HA 106, a DNS server 107, and a DHCP server 108.

The AAA 105 performs authentication, authorization, and billing functions to provide DHCP and MIP services to subscribers of the portable Internet system.

HA 106 performs a home agent function to provide MIP service to AT 101.

The DNS server 107 maps and manages the domain name and the IP address of the AT 101, and performs a function of interpreting and notifying the domain name or the IP address.

In addition, the DHCP server 108 manages address resources that can be operated in the network for each subnet, and performs the function of allocating address resources of the corresponding subnet according to the dynamic address allocation request of the AT 101.

2 is a flowchart illustrating a procedure for providing a handover between subnets to a DHCP user in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 2, the AT 101 of the DHCP service user initiates a DHCP procedure for obtaining an IP address necessary for receiving a wireless packet service after performing an initial registration procedure with the AP 102o. That is, when the AT 101 transmits a message (DHCPDISCOVER) for searching for the DHCP server 108 to the current PAR (old-PAR, hereinafter referred to as oPAR) 103o (S201), the oPAR 103o is connected to the AT 101. ) Adds a DHCP subnet selection option so that the same IP address can be used even if it moves to another PAR to transmit a DHCPDISCOVER message to the DHCP server 108 (S202 to S203). If this option is added, the DHCP server 108 assigns the IP address belonging to the subnet to the AT 101, and the lease time is extended to the same address after the subnet is changed.

Next, the DHCP server 108 transmits a message (DHCPOFFER) including the server information to the AT 101 through the oPAR 103o (S204), and the AT 101 receiving the DHCPOFFER message receives a message for assigning an address. (DHCPREQUEST) is transmitted to the DHCP server 108 via the oPAR 103o (S205). In this case, the oPAR 103o adds a DHCP subnet selection option (S206) and then transmits a DHCPREQUEST message to the DHCP server 108 (S207).

Thereafter, the DHCP server 108 assigns the address 101 and the address lease time belonging to the AT 101 to the AT 101 through the oPAR 103o (DHCPACK, S208). At this time, the oPAR 103o stores and manages the address and lease time allocated to the AT 101. Upon receiving the DHCPACK message, the AT 101 starts a packet data service (S209).

On the other hand, if it is determined that the AT 101 that is in service is moving out of the service area, the signal strength of neighboring neighbor cells is measured to select cells having a specific signal strength or more as a handover candidate cell and access AP (old-AP) or less. The handover is requested by sending a MOB_MSHO-REQ message to the 102).

Next, the oAP 102o that has received the handover request from the AT 101 requests the handover to the oPAR 103o through the HOreq message (S211), and the oPAR 103o requests the handover based on the resource state of the network. It decides whether to accept or not and the destination cell to be handed over.

At this time, when the destination cell to be handed over belongs to another PAR, handover between subnets occurs, and the PHOreq is transmitted to the PAR (new-PAR, hereinafter nPAR) 103n of the subnet to which the oPAR 103o is newly moved. After the message is transmitted, a handover is requested (S212), and the nPAR 103n determines a new AP (new-AP, hereinafter nAP) 102n and transmits a HOind message to request a handover (S213). The nAP 102n then allocates resources for the AT 101 and sends a HOcnf message to the nPAR 103n to inform it that it is ready for handover (S214).

Thereafter, similar information is transmitted to the AT 101 through the PHOrsp, HOrsp, and MOB_MSHO-RSP messages, thereby completing the handover request and admission control steps (S215 to S217).

Thereafter, the oPAR 103o transmits various context information (address information, flow information, QoS, etc.) used for the service connection of the AT 101 to the nPAR 103n through the PCIind message (S218), and the nPAR 103n responds with a PCIcnf message after storing the received information in order to maintain a seamless service (S219). In this case, the lease time remaining for the address of the AT 101, the address of the oPAR 103o used for the DHCP subnet selection option, and the address assigned to the AT 101 in order to support the inter-subnet handover for the DHCP user are used. It should be included in the information.

Meanwhile, in step S217, the AT 101 receiving the MOB_MSHO-RSP message transmits a MOB_HO-IND message to the oAP 102o to inform the start of handover (S220), and the oAP 102o transmits the corresponding AT 101. Context information such as a packet forwarding number, etc. used for communication with the mobile station is transmitted to the nAP 102n through the ACIind, PDTind, and ACIind messages (S221 to S223).

Then, the nAP 102n stores the received context information to maintain the seamless service, and then transmits an ACIcnf message to the nPAR 103n in response (S224).

Next, the nPAR 103n receiving the ACIcnf message creates a tunnel for decapsulating a packet received from the oPAR 130o and then transmits a PDTcnf message to the oPAR 103o (S225-S226). 103o generates an encapsulation tunnel to transmit the packet to be transmitted to AT 100 via the nPAR 103n, which is a new path, and then transmits an ACIcnf message to oAP 102o (S227 to S228). From this time, the packets transmitted to the AT 101 are delivered to the nAP 102n through tunneling, and the oAP 102o detects oPAR 103o and nPAR 103n for packets not transmitted to the AT 101 on the existing path. The transmission is transmitted to the nAP 102n (S229). It is possible to prevent the loss of packets received by the AT 101 during handover between the subnets of the AT 101 of the DHCP service user.

On the other hand, the AT 101 entering the new cell transmits a REG-REQ message to the nAP (102n) (S230 ~ S231).

Then, the nAP 102n sends a CREGreq message to the nPAR 103n to indicate that the AT 101 has re-entered the network (S232), and the nPAR 103n sends a CREGrsp message to the nAP 102n, and nAP ( 102n) initiates the service by sending a REG-RSP message to the AT (101) (S233 ~ S235). At this time, since IP addresses for DHCP users handed over between subnets are already stored in the nPAR 103n and nAP 102n, the AT 101 does not receive a new IP address and is used in the previous oPAR 103o. You can continue to use your address to get services. In addition, the traffic for the AT 101 is continuously transmitted through the tunnel generated between the oPAR 103o and the nPAR 103n.

On the other hand, if the AT 101 needs to extend the lease time for the DHCP address for continuous service use, the AT 101 transmits a DHCPREQUEST message to the DHCP server 108 through the nAP 102n and the nPAR 103n. To request a lease time extension (S236 ~ S238). At this time, the nPAR 103n receiving the DHCPREQUEST message receives the context through the handover procedure to request the DHCP server 108 to extend the lease time of the AT 101 assigned an address belonging to the subnet of the oPAR 103o. After adding the address of the oPAR (103o) included in the information to the DHCP subnet selection option (S237), and transmits a DHCPREQUEST message to the DHCP server 108 (S238).

Therefore, although the DHCP relay's address is changed from oPAR 103o to nPAR 103n, the DHCP server S108 normally extends the lease time and DHCPACK normally because the DHCP subnet selection option is the address of the previously allocated oPAR 103o. Reply with a message (S239).

Next, the nPAR 103n receiving the DHCPACK message transmits the message to the AT 101 through the nAP 102n to extend the lease time.

Through this procedure, continuous service can be provided to an existing address even if a handover between subnets is performed for DHCP users.

Next, a connection release process of a DHCP user handed over between subnets according to an embodiment of the present invention will be described in detail with reference to FIG. 3.

3 is a flowchart illustrating a connection release procedure of a DHCP user handed over between subnets in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 3, if a DHCP user sends a DREG-REQ message to the nAP 102n to terminate service connection after being handed over between subnets (S301), the nAP 102n requests to terminate the service. The DREGreq message is transmitted to the nPAR 103n (S302).

Next, the nPAR 103n receiving the DREGreq message deletes the tunnel (Decap tunnel) created to decapsulate the packet received from the oPAR 103o, and then requests the deletion of the encapsulation tunnel created by the oPAR 103o. In order to transmit the DT-Noti message to the oPAR 103o (S303 to S304). At this time, the DT-Noti message includes the address of the AT 101, the address of the nPAR 103n, and the like necessary to delete the encapsulation tunnel.

After receiving the DT-Noti message, the oPAR 103o deletes the encapsulation tunnel (Encap tunnel), and the nPAR 103n sends the DT-Noti message to the oPAR 103o to notify that the service has been terminated. The message is transmitted to the nAP 102n (S306). The nAP 102n then terminates the service by sending a DREG-CMD message to the AT 101.

Next, a connection release process of a DHCP user handed over between subnets according to the DHCP lease time expiration according to an embodiment of the present invention will be described in detail with reference to FIG. 4.

4 is a flowchart illustrating a connection release procedure of a DHCP user handed over between subnets when a DHCP lease time expires in a portable Internet system according to an embodiment of the present invention.

As shown in FIG. 4, if there is no lease time extension request from the AT 101 until the lease time of the AT address included in the context information received through the handover procedure expires, the nPAR 103n receives nAP ( 102n) transmits a DREGreq message to request the service cancellation for the AT (101) (S401 ~ S402).

Next, the nAP 102n notifies the service cancellation by sending a DREG-CMD message to the AT 101 and, as a result, transmits a DREGrsp message to the nPAR 103n (S403 to S404).

After receiving the DREGrsp message, the nPAR 103n deletes the tunnel (Decap tunnel) created to decapsulate the packet received from the oPAR 103o (S405), and then deletes the encapsulation tunnel (Encap tunnel) created by the oPAR. The DT-Noti message is transmitted to the oPAR 103o to request (S406), and the oPAR 103o receiving the DT-Noti message deletes the encapsulation tunnel (Encap tunnel) (S407).

Meanwhile, FIG. 5 is a diagram illustrating a change of a traffic path according to handover between subnets of a DHCP user in a portable Internet system according to an embodiment of the present invention.

As described above, before handover occurs, traffic passes through the path 501 of CN 110-> oPAR 103o-> oAP 102o-> AT 101, but handover between subnets is After this is done, traffic passes through the path 110 of the CN 110-> oPAR 103o-> nPAR 103n-> nAP 102n-> AT 101. At this time, a tunnel is created between the oPAR 103o and the nPAR 103n through S225 and S227 as shown in FIG. 2, and the generated tunnel uses IP-in-IP or generic routing encapsulation. it means.

On the other hand, after the tunnel is created, the oAP 102o forwards the packets not transmitted to the AT 101 due to the handover occurrence among the received packets to the oPAR 103o to be delivered to the nAP 102n through the tunnel. To help. Since this procedure is performed after the tunnel is created, forwarding of unsent packets is only performed for packets transmitted to the oAP 102o until the tunnel is created.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to the present invention, in a portable Internet system capable of providing both DHCP and MIP services, when a DHCP service user moves between packet access routers and receives services, handover between subnets can be performed and the same IP address can be used. This can provide seamless service to DHCP service users.

In addition, when a handover occurs between subnets, a tunnel between an existing packet access router and a new packet access router can be created to provide a seamless service to a DHCP service user without packet loss during handover.

Claims (11)

A method for providing handover to a mobile terminal using a Dynamic Host Configuration Protocol (DHCP) service in a first subnet of a portable internet system, the method comprising: a) adding an option for selecting the first subnet when allocating an IP address for the mobile terminal and providing the DHCP server to a DHCP server; b) when the mobile terminal requests a handover to a second subnet to be handed over according to a handover request from the mobile terminal, in the option of selecting the IP address and the subnet assigned to the mobile terminal in step a). Providing context information including an address of the first subnet used to the second subnet; And c) creating an encapsulation tunnel to the second subnet for sending a packet to be delivered to the mobile terminal to the second subnet upon accepting a handover from the second subnet; Handover providing method comprising a. The method of claim 1, Step a), Receiving an IP address assignment request message from the mobile terminal; Adding an option for selecting the first subnet to the received IP address allocation request message and transmitting the option to the DHCP server; And Receiving an IP address belonging to the first subnet and a lease time of the IP address from the DHCP server and transmitting the IP address to the mobile terminal; Handover providing method comprising a. The method of claim 1, Step b), Receiving a handover request message from the mobile terminal to the second subnet; Requesting handover to the second subnet designated by the received handover request message and receiving an acceptance; And Transmitting context information including the IP address of the mobile terminal, the first subnet address and the lease time of the IP address to the second subnet; Handover providing method comprising a. The method according to any one of claims 1 to 3, After step c), Deleting the encapsulation tunnel created in step c) in response to a request from the second subnet. The method of claim 4, wherein And the request from the second subnet includes the IP address of the mobile terminal and the address of the second subnet for deleting the encapsulation tunnel created in step c). In the method of providing a handover to a mobile terminal moving to a second subnet while using a Dynamic Host Configuration Protocol (DHCP) service in a first subnet of a portable Internet system, a) an IP address of the mobile terminal and an address of the first subnet, together with a handover request from the first subnet, wherein the address of the first subnet is an address used as a subnet selection option transmitted by the first subnet to a DHCP server Receiving context information including the lease time of the IP address; b) creating a decapsulation tunnel to the first subnet for receiving packets from the first subnet to be delivered to the mobile terminal; And c) allowing registration of the mobile terminal to initiate a DHCP service for the mobile terminal in the second subnet Handover providing method comprising a. The method of claim 6, Step a), Receiving a handover request message from the first subnet; Allocating resources for the mobile terminal and accepting the handover request; And Receiving context information from the first subnet including the IP address, the address of the first subnet and the lease time Handover providing method comprising a. The method according to claim 6 or 7, After step c), Receiving a request for extending the lease time of the IP address from the mobile terminal; Requesting the DHCP server to extend the requested lease time using an address of the first subnet included in the context information received in step a) as an option for selecting a subnet; And Notifying the mobile terminal of the extension of the lease time of the IP address with the permission of the lease time extension from the DHCP server; Handover providing method comprising a. The method of claim 6, After step c), Receiving a termination request for the DHCP service from the mobile terminal; Deleting the decapsulation tunnel created in step c) according to the request for termination of access to the DHCP service; Requesting deletion of an encapsulation tunnel to the first subnet, wherein the encapsulation tunnel is generated by the first subnet for transmission of a packet delivered to the mobile terminal upon handover of the mobile terminal; And Notifying the mobile terminal that the DHCP service for the mobile terminal has been disconnected; Handover providing method comprising a. The method of claim 6, After step c), Determining whether there is a request for extending the lease time from the mobile terminal until the lease time of the IP address expires; If it is determined that there is no request for extension of the lease time from the mobile terminal until the lease time of the IP address expires, notifying the mobile terminal of the termination of the DHCP service; Deleting the decapsulation tunnel created in step c); And Requesting deletion of an encapsulation tunnel to the first subnet, wherein the encapsulation tunnel is generated by the first subnet for transmission of packets delivered to the mobile terminal upon handover of the mobile terminal; Handover providing method further comprising. The method of claim 9 or 10, The request for deleting the encapsulation tunnel to the first subnet includes an IP address of the mobile terminal and an address of the second subnet.

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