KR20030017194A - Mobile internet protocol system and registration method on a hand-off event in the same - Google Patents

Abstract

PURPOSE: A mobile IP(Internet Protocol) system and a registration method when performing a hand-off in the same are provided to prevent the loss of a datagram according to the hand-off by performing the registration of an HA(Home Agent) through a PFA(Previous Foreign Agent) in case that a mobile node is moved from the PFA to an NFA(New FA) and the hand-off is generated. CONSTITUTION: An HA(100) maintains location information of a mobile node(400). A PFA(200) cooperates with the HA(100), transmits data to the mobile node(400), and previously registers the mobile node(400). An NFA(300) cooperates with the HA(100), transmits data to the mobile node(400), and receives the request of a new registration according to the generation of a hand-off by the movement of the mobile node(400). The PFA(200) re-tunnels a tunneled datagram from the HA(100) to the NFA(300). When the mobile node(400) is registered in the HA(100) through the NFA(300), the mobile node(400) is registered through the PFA(200).

Description

Mobile internet protocol system and registration method on a handoff in the mobile internet protocol system

The present invention relates to a system to which the Mobile Internet Protocol (hereinafter referred to as IP) is applied. In particular, the present invention relates to a mobile Internet protocol system for preventing the loss of datagrams transmitted to a mobile node when a handoff occurs due to the mobile node. The present invention relates to a registration method during handoff in a mobile Internet protocol system.

Along with the rapid proliferation of the Internet, portable devices such as laptops and PDAs (Personal Digital Assistants) are widely used. Traditionally, the Internet has been developed with the fixed terminal environment fixed in one place without moving, but just as the voice network has evolved from fixed network to mobile communication network, the Internet is naturally expanding into the mobile internet field. Mobile IP is a standard established by the Internet Engineering Task Force (IETF) to build this mobile Internet.

In order to implement such a mobile IP environment, three components, a mobile node, a home agent (hereinafter referred to as HA), and an external agent (hereinafter referred to as FA) should be provided.

A mobile node is a host or router that changes its Internet access point from one network to another without changing its IP address, and that mobile node can communicate with its host on the Internet at its own unique IP address anywhere. .

The HA is a router that exists in the mobile node's home network and maintains location information of the mobile node and transmits data to the mobile node that is mobilely connected to the external network.

The FA is a router in charge of data transmission to the mobile node in cooperation with the HA in the external network visited by the mobile node.

Mobile IP operation is largely divided into agent discovery, registration, and tunneling operations, and IP data destined for itself at any location on the Internet to a mobile node, which refers to a moving host or router by each operation. Enables reception of grams (datagr am).

When a mobile node in communication moves from a currently registered FA to another FA, that is, when it moves from a current external network to another external network, a change of a link layer access point is called a hand-off. When the mobile node detects a handoff, it attempts to register at a new FA (New FA, hereinafter referred to as NFA). At this time, the IP datagram continuously transmitted by the counterpart node in communication is naturally tunneled to the FA (Previous FA, hereinafter referred to as PFA) previously registered by HA. In this case, the PFA cannot deliver tunneling data sent by the HA to the mobile node that is already out of its area. Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

1 is a diagram illustrating a registration process during handoff in a conventional mobile IP system.

As shown in FIG. 1, the mobile node 400 registered with the PFA 200 and communicating with the counterpart node 500 via the HA 100 is advertised by an external agent, PFA 200 or NFA 300. The mobile agent detects a move to the NFA 400 by receiving a mobile agent advertisement message or various handoff detection methods, and attempts to newly register the HA 100.

At this time, the mobile node 400 transmits a registration request message in which the HA address field is set to the HA address of the mobile node 400 to the IP datagram, and the destination address in the header of the IP datagram is the NFA 300. It becomes an address.

Receiving the IP datagram including the registration request message, the NFA 300 refers to the HA address field in the registration request message and includes the registration request message received in the IP datagram with the HA address as the destination address of the IP header. To the HA 100.

The HA 100 may identify the new location of the mobile node 400 through the registration request message received as described above, and send data that was tunneled to the PFA 200 to the NFA 300.

However, the farther the distance between the mobile node 400 and the HA 100 is, the longer it takes to register as described above. During this time, the HA 100 that does not know the state of the mobile node 400 is the counterpart node 500. Intercepts the data sent by the tunnel continues to the PFA (200).

Therefore, the PFA 200 cannot deliver the data received by the HA 100 to the mobile node 400 so that the data is lost or sent back to the HA 100 to increase retransmission at higher layers. There is a problem that causes a routing cycle between the HA 100 and the PFA 200.

As a technique for solving a problem in the handoff of the mobile node as described above, CE Perkins and the like have all nodes participating in ROMIP (Route Optimization in Mobile IP) to exchange the latest mobility binding information of the mobile node, so that the PFA sends to the NFA. A method of inducing tunneling datagrams to retunneling has been proposed ('Optimized smooth handoffs in mobile IP', Computers and Communications.Proceedings, IEEE International Symposium, draft-ietf-mobileip-optim-09.txt, 1999). Since NFA requires PFA to request a separate binding update request, a lot of messages and extensions used for binding are required, and the algorithm is complicated.

In addition, researches for minimizing data loss have been conducted from various angles, but most of them are HA-involved, mobility management through a location register, or a buffered store-and-forward transmission method to increase the load of HA or FA and to use unnecessary control messages. There is a problem.

Accordingly, an object of the present invention is to solve the above-described problems, and when the mobile node moves from the PFA to the NFA and a handoff occurs, the PFA is naturally present by performing the registration of the HA through the PFA. The present invention provides a mobile IP system capable of preventing a loss of datagram due to handoff by knowing a location, and a registration method during handoff in the mobile IP system.

1 is a diagram illustrating a registration process during handoff in a conventional mobile IP system.

2 is a schematic block diagram of a mobile IP system according to an embodiment of the present invention.

3 is a diagram illustrating a format of a mobility agent advertisement message used in a mobile IP system according to an embodiment of the present invention.

4 is a diagram illustrating a format of a registration request message used in a mobile IP system according to an embodiment of the present invention.

5 is a flowchart illustrating a registration method during handoff in a mobile IP system according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a path through which a registration request message used in the registration method in the handoff of FIG. 5 is routed to the PFA 200.

Explanation of symbols on the main parts of the drawings

100: HA 200: PFA 300: NFA

400: mobile node 500: counter node 610, 620, 630: IP datagram

640: Visitor List

Mobile Internet Protocol system according to a feature of the present invention for achieving the above object,

A home agent for maintaining location information of the mobile node; A first external agent capable of transmitting data to the mobile node in cooperation with the home agent, wherein the mobile node is registered; And a second foreign agent capable of transmitting data to the mobile node in cooperation with the home agent, wherein a new registration is required due to a handoff caused by the movement of the mobile node. And retunneling the datagram tunneled from the home agent to the second external agent, wherein the mobile node registers via the first external agent when registering with the home agent through the second external agent. It features.

The mobility agent advertisement message broadcast by the first external agent includes information indicating that the first external agent has a retuning function.

When the mobile node sends a registration request message to the second foreign agent requesting registration with the home agent, the registration request message includes the address of the first foreign agent.

The mobile node includes information indicating that the first foreign agent has a retuning function in a registration request message sent to the second foreign agent.

When the mobile node passes through the first foreign agent when registering with the home agent through the second foreign agent, the first foreign agent adds the address of the second foreign agent to the visitor list of the mobile node. Perform a temporary registration.

When a datagram to be transmitted from the home agent to the mobile node is received by tunneling to the first foreign agent, the first foreign agent receives the address through the address of the second foreign agent referenced in the visitor list of the mobile node. The datagram is retuned to the second external agent and transmitted.

The mobile node may request temporary deregistration with the first external agent to stop the first external agent from retuning the datagram transmitted from the home agent due to the temporary registration.

In addition, the registration method during handoff in the mobile Internet protocol system according to an aspect of the present invention,

A new agent that maintains location information of a mobile node, a first external agent in which the mobile node is registered among the plurality of foreign agents, and a new registration due to a handoff occurrence due to movement of the mobile node among the plurality of foreign agents A registration method in handoff in a mobile internet protocol system comprising a second foreign agent required,

A first step of the mobile node sending a registration request message to the second foreign agent for registration with the home agent; A second step in which the second foreign agent receives a registration request message sent from the mobile node and retransmits it to the first foreign agent; After the first foreign agent receives a registration request message sent from the second foreign agent, the second foreign agent is added to the visitor list of the mobile node to temporarily register and register the received registration request message. Retransmitting to the home agent; A fourth step in which the home agent receives a registration request message sent from the first external agent and performs a registration process for the mobile node, and then transmits a registration response message for the registration request message to the second external agent. step; And a fifth step in which the second foreign agent receives a registration response message sent from the home agent and retransmits it to the mobile node.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic block diagram of a mobile IP system according to an embodiment of the present invention.

As shown in FIG. 2, a mobile IP system according to an embodiment of the present invention includes an HA 100, a PFA 200, and an NFA 300.

Mobile node 400 has the functionality of a mobile host described in IETF's RFC 2002 and is connected to PFA 200 or NFA 300 via wireless communication.

HA 100, PFA 200 and NFA 300 also have the functions of each home agent and foreign agent described in RFC 2002.

The HA 100 maintains location information of the mobile node 400, transmits data to the mobile node 400 connected to the PFA 200 or the NFA 300, and receives data from the mobile node 400. To the partner node 500.

The PFA 200 and the NFA 300 are connected to the HA 100, respectively, and are routers that are responsible for data transmission to the mobile node 400 in cooperation with the HA 100.

The PFA 200 is an FA registered before the movement when the mobile node 400 moves and a handoff occurs, and the NFA 300 is an FA registered by the mobile node 400 moving and newly registered.

A handoff occurs while the mobile node 400 moves from the PFA 200 to the NFA 300, in which case the mobile node 400 attempts to register with the NFA 300.

When registering the mobile node 400 in the NFA 300, a path is set such that a registration request message and a registration response message pass through the PFA 200. In this case, the registration response message may be delivered directly to the NFA 300 without passing through the PFA 200.

The registration request message sent by the mobile node 400 is transmitted in the order of the NFA 300, the PFA 200, and the HA 100.

At this time, the PFA 200 temporarily registers a new care address (hereinafter referred to as a COA) of the mobile node in the visitor list through a registration request message received from the mobile node 400.

As described above, the COA of the NFA 300 moved by the mobile node 400 is recorded in the PFA 200, so that the data of the mobile node 400 tunneled to the PFA 200 by the HA 100 is stored by the PFA 200. It is then encapsulated in back encapsulated COA and delivered to NFA 300. The NFA 300 decapsulates data transmitted from the PFA 200 again and delivers the data to the mobile node 400 so that loss of data delivered to the mobile node 400 during handoff may be prevented.

The registration response message sent by the HA 100 in response to the registration request message of the mobile node 400 is directly transmitted to the mobile node 400 through the NFA 300, but in this case, the NFA ( 300).

The temporary registration with the PFA 200 is released by the direct release request of the mobile node 400 or automatically when the valid time at the PFA 200 expires.

Direct release by the mobile node 400 is performed by the mobile node 400 directly requesting the PFA 200 to release the temporary registration when a successful registration response message from the HA 100 is received by the mobile node 400. do.

On the other hand, the release by the end of the validity time is performed when there is no re-registration request by the mobile node 400 when the registration validity time in the visitor list of the PFA 200 ends. In this case, the PFA 200 checks whether there is data continuously tunneling from the HA 100 toward the mobile node 400 without immediately releasing the temporary registration, and if the registration validity time is expired, the data that continues to be tunneled If there is, the PFA 200 may reset the registration valid time by an arbitrary time. If there is no data continuously tunneled from the HA 100, the PFA 200 immediately releases the temporary registration.

As shown in the attached FIG. 3 and FIG. 4, the PFA 200 sets one bit of the reserved agent of the mobility agent advertisement message and the registration request message of the mobile IP for temporary registration. Provisional Registration Flag (hereinafter referred to as P flag).

The P flag in the mobility agent advertisement message broadcasted by the FA is used as a flag indicating that the broadcasting FA has a temporary tunnel mechanism execution capability and allows temporary registration.

On the other hand, the P flag of the registration request message transmitted from the mobile node 400 is handoff whether the message is a registration message of the newly visited mobile node 400 when the PFA 200 receives the registration request message destined for the destination. It is used to distinguish whether the registration message for temporary registration sent from the mobile node 400 being used.

In addition, the HA address field of the registration request message can be modified to the HA address / PFA address field so that routing by the temporary tunnel between the PFA 200 and the NFA 300 is possible, so that not only the HA address but also the PFA 200 address can be set. Make sure Therefore, when the mobile node 400 sends a registration request message to the NFA 300, the mobile node 400 sets the address of the PFA 200 in the HA address / PFA address field and sends the registration request to the PFA 200 through the NFA 300. The message is delivered to allow temporary registration.

On the other hand, there are a number of fields and flags in addition to the above-described P flag and HA address / PFA address field in FIG. 3 and FIG. The detailed description is omitted here.

When the mobile node 400 receives the mobility agent advertisement message from the FA, it examines each flag and field to determine and record whether to use a temporary tunnel mechanism to be used at a later point in time. The information recorded in this way is used when the mobile node 400 detects a handoff occurrence.

In more detail, the mobile node 400 checks in the received mobility agent advertisement message an F flag, which is a flag indicating that the agent that sent this message is a FA, and if the F flag is 1 it is a FA and again sets the P flag. Check it. If the P flag is 1, the mobile node 400 determines that the current FA (which becomes the PFA when a handoff occurs) that sent the mobility agent advertisement message supports a temporary tunnel mechanism during handoff.

If the F flag of the received mobility agent advertisement message is 0 and it is determined that the agent is not a FA or the R flag, which is a flag requiring the registration and use of the FA, is determined to be 0 and not registered with the FA, Mobile node 400 does not attempt temporary registration by a temporary tunnel mechanism.

On the other hand, when the mobile node 400 first attempts to connect from the FA or moves from HA to FA, the P node of the registration request message is set to 0, and the HA address / PFA address field is set to the HA address and transmitted.

When the FA broadcasts the mobile agent advertisement message, the FA broadcasts by setting the P flag indicating 1 to the temporary tunnel mechanism support capability at handoff of the mobile node.

The FA may operate as the PFA 200 for any mobile node or may operate as the NFA 300. When the FA receives a registration request message with the P flag set to 1 from the mobile node, it determines whether a visitor list of the mobile node exists and determines whether to operate as a PFA or an NFA.

If the visitor list of the mobile node does not exist, the FA at this time operates as an NFA, and considers the mobile node as a newly visited node and creates a new visitor list.

However, if there is a visitor list of the mobile node, the FA at this time acts as a PFA, and performs a temporary registration procedure.

5 is a flowchart illustrating a registration method during handoff in a mobile IP system according to an embodiment of the present invention. Hereinafter, a registration operation during handoff of a mobile IP system according to an embodiment of the present invention will be described with reference to FIG. 5. .

First, the PFA 200 broadcasts by setting the P flag of the mobility agent advertisement message to 1 so that the mobile node 400 already knows that the PFA 200 has a temporary tunnel mechanism support capability upon handoff, and thus PFA ( It is assumed that the address of 200 is also recorded.

When the mobile node 400 detects the NFA 300 and detects a handoff occurrence, the P flag is set to 1 and the HA address / PFA address field is set to the PFA 200 address for registration in the NFA 300. A registration request message is transmitted to the NFA 300 (S10).

The NFA 300 receiving the registration request message from the mobile node 400 confirms that the P flag of the registration request message is set to 1, and checks whether the visitor list of the mobile node 400 exists. Since the NFA 300 is a FA where the mobile node 400 moves and arrives, the NFA 300 operates as the NFA 300 because there is no visitor list of the mobile node 400. Accordingly, the NFA 300 generates a visitor list of the mobile node and simultaneously sends the registration request message to the PFA 200 by referring to the address of the PFA 200 set in the HA address / PFA address field of the registration request message. It transmits (S20). Of course, the P flag of the registration request message at this time is set to one.

The PFA 200 receiving the registration request message from the NFA 300 confirms that the P flag of the registration request message is set to 1, and checks whether the visitor list of the corresponding mobile node 400 exists. Since the PFA 300 is a FA previously registered by the mobile node 400, the PFA 300 operates as the PFA 200 because a visitor list of the mobile node 400 exists.

Therefore, the PFA 200 processes the received registration request message and temporarily registers the visitor list by adding the address of the FA where the mobile node 400 is located, that is, the COA which is the address of the NFA 300.

As described above, since the COA of the NFA 300 where the mobile node 400 is located is added to the visitor list of the PFA 200, data tunneled from the HA 100 to the PFA 200 is referred to the NFA 300 by referring to the COA. The data is retuned and finally delivered to the mobile node 400 to prevent data loss during handoff.

Meanwhile, the PFA 200 searches the visitor list of the mobile node 400 to transmit the registration request message received from the NFA 300, and sets the HA address as the destination address of the IP header to the HA 100. Transmit (S30).

The HA 100 receiving the registration request message from the PFA 200 newly registers the current location of the corresponding mobile node 400 and directly transmits the registration response message to the NFA 300 (S40). At this time, the HA 100 transmits a registration response message to the PFA 200, and the PFA 200 searches the visitor list of the corresponding mobile node 400 and sets the found COA as the destination address of the IP header to NFA ( 300).

The NFA 300 receiving the registration response message from the HA 100 or the PFA 200 retransmits the registration response message to the mobile node 400 (S50).

After receiving the registration response message from the NFA 300, the mobile node 400 confirms that registration is successfully completed by the HA 100, and then temporarily registers the PFA 200 to prevent data loss due to a handoff occurrence. In order to release the PFA 200, the temporary registration release request message may be transmitted (S60). At this time, the temporary deregistration request by the mobile node 400 is selectively performed by the mobile node 400, and when the mobile node 400 does not perform the temporary deregistration request, the valid time of the registration request message. Upon temporary termination, temporary registration is automatically released.

As such, when the temporary registration in the PFA 200 is released, since the formal registration of the mobile node 400 by the HA 100 is successfully performed, the retuning operation of data by the PFA 200 is stopped.

On the other hand, if the mobile node 400 does not receive the registration response message within the registration valid time after transmitting the registration request message to the NFA 300, the mobile node 400 attempts to register again with the basic mobile IP procedure.

FIG. 6 is a diagram illustrating a path through which a registration request message used in the registration method in the handoff of FIG. 5 is routed to the PFA 200.

As shown in FIG. 6, the IP datagram 610 including the registration request message sent by the mobile node 400 to the NFA 300 has a destination address of the NFA 300, a P flag of 1, and an HA. The Address / PFA Address field is filled with the address of the PFA 200.

The NFA 300 copies the address of the HA address / PFA address field of the received message to the next destination address (see 620) of the IP header and sends it again.

The PFA 200 adds the COA of the received registration message to the visitor list 640 of the mobile node 400 and uses it for data transmission according to the temporary registration.

At this time, the PFA 200 finds the HA address in the visitor list 640 of the mobile node 400 and sets it as the next destination address (see 630) of the registration request message to be transmitted to the HA 100.

On the other hand, the authentication between the mobile node 400 and the HA 100 in the registration procedure is made by the use of the authentication extension field between the mobile node 400 and the HA 100. In this case, the authentication extension field between the mobile node 400 and the HA 100 of the registration request message passing through the PFA 200 does not change.

The authentication between the mobile node 400 and the FA is optional. If the authentication between the mobile node 400 and the FA is required, the authentication between the mobile node 400 and the PFA 200 is already performed by the mobile node for the first time. It will happen at the time of visit.

Authentication between the mobile node 400 and the NFA 300 is an authentication extension field between the mobile node 400 and the FA during registration.

Therefore, in the present invention in which the mobile node 400 registers with the HA 100 through the temporary registration of the PFA 200, the mobile node 400 and the NFA 300, the PFA 200, and the HA 100 may be connected to each other. No separate authentication process is required.

Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.

According to the present invention, the number of datagrams that may be lost when a handoff occurs due to the movement of the mobile node 400 may be reduced. The longer the distance between the HA 100 and the mobile node 400 is, the longer the time required for registration becomes.

In addition, it does not require the use of additional resources that burden the network, does not use additional messages and extension fields, and does not require a separate authentication procedure.

Claims (18)

In the mobile Internet protocol system, A home agent for maintaining location information of the mobile node; A first external agent capable of transmitting data to the mobile node in cooperation with the home agent, wherein the mobile node is already registered; And A second foreign agent capable of transmitting data to the mobile node in cooperation with the home agent and requiring a new registration due to a handoff occurring due to the movement of the mobile node; Including; The first foreign agent has a function of retuning a datagram tunneled from the home agent to the second foreign agent, When the mobile node registers with the home agent through the second external agent, registers via the first external agent Mobile Internet Protocol System. The method of claim 1, The mobile internet protocol system of claim 1, wherein the mobile agent includes information indicating that the first foreign agent has a retuning function in the mobility agent advertisement message broadcast by the first foreign agent. The method of claim 2, And wherein said information is indicated by one bit of a reservation bit of said mobility agent advertisement message. The method of claim 1, A mobile internet protocol system including an address of the first foreign agent in the registration request message when the mobile node sends a registration request message to the second external agent requesting registration with the home agent. The method of claim 4, wherein The mobile Internet protocol system, characterized in that the registration request message sent by the mobile node to the second foreign agent includes the information that the first foreign agent has a retuning function. The method of claim 5, And wherein said information is indicated by one bit of a reservation bit of said registration request message. The method of claim 1, When the mobile node passes through the first foreign agent when registering with the home agent through the second foreign agent, the first foreign agent sends a care of address (COA) of the mobile node to the visitor list of the mobile node. Mobile Internet Protocol system, characterized in that to perform a temporary registration in addition to. The method of claim 7, wherein When a datagram to be transmitted from the home agent to the mobile node is received tunneled to the first foreign agent, the data is transmitted through the COA of the mobile node referenced by the first foreign agent in the visitor list of the mobile node. The mobile internet protocol system, characterized in that the re-tunneled gram to the second external agent. The method of claim 8, The mobile node requests a temporary deregistration with the first external agent to stop the first external agent from retuning the datagram transmitted from the home agent due to the temporary registration. system. The method of claim 7, wherein The temporary registration at the first foreign agent is released when the valid time of the registration request message ends. The method of claim 10, The temporary deregistration is delayed for a certain time when there is data tunneled from the home agent to the mobile node. A home agent for maintaining location information of the mobile node, a first external agent capable of transmitting data to the mobile node in cooperation with the home agent, and registered with the mobile node, and in cooperation with the home agent to the mobile node In the registration method at the time of handoff in the mobile Internet protocol system including a second foreign agent capable of data transmission of the new node and a new registration is required due to the handoff caused by the movement of the mobile node, A first step of the mobile node sending a registration request message to the second foreign agent for registration with the home agent; A second step in which the second foreign agent receives a registration request message sent from the mobile node and retransmits it to the first foreign agent; After the first foreign agent receives a registration request message sent from the second foreign agent, the second foreign agent is added to the visitor list of the mobile node to temporarily register and register the received registration request message. Retransmitting to the home agent; A fourth step in which the home agent receives a registration request message sent from the first external agent and performs a registration process for the mobile node, and then transmits a registration response message for the registration request message to the second external agent. step; And A fifth step in which the second foreign agent receives the registration response message sent from the home agent and retransmits it to the mobile node; Registration method in the handoff in a mobile Internet protocol system comprising a. The method of claim 12, In the first step, the registration request message includes the information that the first external agent has a re-tunneling function registration method in the handoff in the mobile Internet protocol system. The method of claim 13, And in the first step, the registration request message includes an address of the first foreign agent. The method of claim 14, A mobility agent advertisement message broadcast by the first external agent includes information that the first external agent has a retuning function, The mobile node confirms that the address of the first foreign agent included in the registration request message is that the first foreign agent has a retuning function by the mobility agent advertisement message broadcast from the first foreign agent. When recorded in the mobile node. How to register at handoff in Mobile Internet Protocol system. The method of claim 14, In the second step, the second foreign agent retransmits the registration request message to the first foreign agent with reference to the address of the first foreign agent included in the registration request message. How to register at handoff from. The method of claim 12, In the third step, the first external agent finds the address of the home agent from the visitor list of the mobile node and transmits the registration request message to the home agent. How to register. The method of claim 12, After the fifth step, the mobile node further requesting temporary deregistration of the first foreign agent.