KR100688609B1 - Handover method in Hybrid Mobile IPv6 using buffer and recording medium having program thereof - Google Patents

Abstract

The present invention relates to a handover method, and more particularly, to a handover method using a buffer in Hybrid Mobile IPv6. The hybrid mobile IP that created tunneling between the old access router (PAR) and the new access router (NAR) in order to minimize packet loss while maintaining the tunneling between the MAP and the new access router (NAR) used by FHMIPv6. Handover method. After the mobile node MN arrives at a new access router NAR, local binding update (LBU) used by HMIPv6 may be performed to reduce signal overhead or packet forwarding delay.

Hybrid, Mobile IP, MIPv6, Buffer, Handover

Description

Handover method in Hybrid Mobile IPv6 using buffer and recording medium having program

1 is a diagram illustrating a handover system of a conventional FHMIPv6.

2 illustrates the overall flow of the handover method according to the invention.

3 is a flow diagram illustrating a handover method according to an embodiment of the present invention.

4 illustrates a flow of a handover method according to another preferred embodiment of the present invention.

5 is a flowchart illustrating a handover method according to another preferred embodiment of the present invention.

6 is a diagram illustrating an operation algorithm of the PAR 220 according to the present invention.

<Description of Symbols for Main Parts of Drawings>

200: partner node (CN) / home agent (HA)

210: MAP

220: old access router (PAR)

230: new access router (NAR)

240: mobile node (MN)

The present invention relates to a handover method, and more particularly, to a handover method using a buffer in Hybrid Mobile IPv6.

With the increase of Internet users and the development of Internet application technology, the Internet Protocol (IP) is widely used in related technologies such as wired and wireless communication networks as well as existing data networks. Therefore, standardization of the next generation communication network is being made in the direction of IP based construction from the terminal to the core network. As a technology for supporting mobility of a terminal in a next generation IP version 6 (IPv6) network, there is a mobile IPv6 (hereinafter referred to as 'mobile IPv6') of the Internet Engineering Task Force (IETF). Mobile IPv6 is designed to provide mobile nodes (MNs) on a wireless IPv6 network with transparent mobility to higher layers such as TCP in the OSI 3 layer without interruption of the ongoing transport layer. In Mobile IPv6, whenever a mobile host changes its communication location, the mobile host uses its Care of Address (CoA) to send its current location to its Home Agent (HA) and its Correspondent Node (CN). By performing a BU (Binding Update) to maintain the connectivity to itself even when moving. However, when the mobile node MN arrives at a new access router (NAR) while moving, a packet transmission delay problem and a packet loss problem may occur during a handover time.

Conventional methods for solving this problem include fast handover technology (FMIPv6; Fast Handover Mobile IPv6, hereinafter referred to as 'FMIPv6'), hierarchical Moblie Ipv6 (hereinafter referred to as `` HMIPv6 ''), and two types. Fast handover technology for hierarchical mobile IP combining the method (FHMIPv6) (hereinafter referred to as 'FHMIPv6').

Fast handover technology (FMIPv6) has been proposed to provide real-time services such as VoIP in mobile terminals of IP networks by reducing handover delay time. When a mobile node (MN) moves from a previous access router (PAR) to a new access router (NAR), tunneling is performed between the old access router (PAR) and the new access router (NAR) to forward packets. That's the way. That is, Layer 2 handover expectation information is expected to be received in advance in Layer 2 using trigger information, and Layer 3 uses this information in advance to use CoA (Care) to be used in the communication area of a new access router (NAR). of Address). Therefore, after the second layer handover is completed in Mobile IPv6, a new CoA can be configured to reduce the time delay of handover caused by binding update (BU). After the mobile node MN arrives at the new access router NAR, the mobile node MN must inform the counter node CN and the home agent HA of the mobile node MN through the binding update process. As a result, compared to the hierarchical mobile IP (HMIPv6) to be described later, there is a disadvantage in that it is more expensive as additional signal processing between the Mobile Anchor Point (MAP) and the counterpart node (CN) / Home Agent (HA).

The hierarchical mobile IP (HMIPv6) is a local location movement of the mobile node (MN) is local to the intermediate node (MAP) close to the mobile node (MN) instead of the partner node (CN) or the mobile agent (MN) home agent (HA) By performing a binding update (LBU), a binding update time and signal overhead in handover are reduced. However, this method can reduce the binding update time during handover, compared to the existing Mobile IPv6, but only a small portion of the three-layer binding update time after the second layer is limited. In addition, while the mobile node MN moves from the old access router PAR to the new access router NAR, packets transmitted to the old access router PAR are lost.

FHMIPv6 combines the two methods described above, FMIPv6 and HMIPv6. The mobile node (MN) does not create tunneling between the old access router (PAR) and the new access router (NAR) before moving, but instead creates a tunneling between the middle man (MAP) and the new access router (NAR) to send packets, After the MN arrives at the new access router (NAR), the MN and the local binding update (LBU) are performed.

1 is a diagram illustrating a handover system of a conventional FHMIPv6.

Referring to FIG. 1, a system for performing handover includes a partner node (CN) / home agent (HA) 100, an intermediary (MAP) 110, an old access router (PAR) 120, and a new node connected to the Internet. It consists of an access router (NAR) 130 and a mobile node (MN) 140. The counterpart node (CN) 100 refers to a counterpart terminal communicating with a mobile terminal. The home agent (HA) 100 has registration information of a mobile node (MN) 140 among routers in a home network. The router refers to a router that sends a datagram to a current location of a mobile node (MN) 140 having an external network. The middle man (MAP) 110 is a router of the area where the mobile node (MN) 140 is located and manages local mobility. The old access router (PAR) 120 is the access router to which the current mobile node (MN) 140 is connected and the new access router (NAR) 130 is the access router in the area to which the mobile node (MN) 140 is to move. . The old access router (PAR) 120 and the new access router (NAR) 130 refer to a router having a wireless interface capable of wireless connection with the mobile node (MN) 140. A Redirectional Tunnel (RT) 140 is created during handover between the MAP 110 and the new Access Router (NAR) 130. The mobile node (MN) 140 refers to a host or a router that changes its network connection location. When the mobile node (MN) 140 moves from the old access router (PAR) 120 to the new access router (NAR) 130, the mobile node (MN) 140 moves to the new access router (NAR) ( Until the binding update (BU) is completed in 130, the packet transmitted from the counter node (CN) / home agent (HA) 100 to the mobile node (MN) 140 is delivered through the following steps.

First, a packet destined for the mobile node (MN) 140 from the counter node (CN) / home agent (HA) 100 to the mobile node (MN) 140 according to the operation specified in Mobile IPv6 is an intermediary in which CoA of the mobile node (MN) 140 is registered. (MAP) is delivered to (110) (S100). Packets forwarded to the MAP 110 are transferred to the MN using a bidirectional tunnel between the MAP 110 and the previous access router (PAR) 120 according to the behavior specified in the hierarchical mobile IP. Forwarded to 140. The mobile node (MN) 140 has been moved from the old access router (PAR) 120 to the new access router (NAR) 130 and lost its connection with the old access router (PAR) 120, so that the MAP (MAP) ( 110 intercepts the packet forwarded to the mobile node (MN) 140, and intercepts the redirection tunnel (RT) 150 created between the MAP 110 and the new access router (NAR) 130. Forwarding by using (S110). The new access router (NAR) 130 transmits a packet to the mobile node (MN) 140 via a wireless link after a link is established with the mobile node (MN) 140.

In this method, if the mobile node (MN) moves to a new access router (NAR) before receiving a fast binding binding (FBACK) signal, which is a tunneling generation completion signal, there is no tunneling between the old access router (PAR) and the new access router (NAR0). There is a problem that packet loss occurs.

Therefore, the present invention tunnels between the old access router (PAR) and the new access router (NAR) to minimize packet loss while still using the tunneling between the MAP and the new access router (NAR) used in FHMIPv6. Provides a handover method of hybrid mobile IP made.

In addition, the present invention performs handover of hybrid mobile IP, which can reduce signal overhead or packet forwarding delay by performing local binding update (LBU) used by HMIPv6 after mobile node MN arrives at new access router (NAR). Provide a method.

In addition, the present invention seeks to reduce tunneling only when there is a packet to be sent between the old access router (PAR) and the new access router (NAR) to reduce the signal overhead and bandwidth waste used for tunneling. A handover method of a hybrid mobile IP using a buffer is provided.

In order to achieve the above object, according to an aspect of the present invention, the first router, the second router, and the middleman for managing the local mobility of the mobile node in the communication area of the first router and the communication area of the second router ( In a handover method of a hybrid mobile IPv6 including a mobile anchor point (MAP), (a) the first router requests a first tunneling between the first router and the second router; Receiving a first tunneling message, wherein the mobile node moves from a communication area of the first router to a communication area of the second router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is no packet to transmit as a result of the checking in step (b), the first router checking whether a handover complete message is received from the intermediate person; And (d) if the first router does not receive the handover complete message as a result of the checking in step (c), repeats step (b) to step (c), and if received, transmits to the second router. A handover method of a hybrid mobile IP using a buffer including transmitting the handover complete message may be provided.

Advantageously, step (d) comprises: if there is a packet corresponding to the first tunneling message in the buffer during steps (b) to (c), the first router generates the first tunneling; Forward the packet to the second router.

In order to achieve the above objects, according to another aspect of the present invention, an intermediary for managing local mobility of a mobile node in the communication area of the first router, the second router and the first router and the communication area of the second router ( A method of handover of a hybrid mobile IP comprising: (a) the first router receiving a first tunneling message requesting a first tunneling between the first router and the second router, wherein The mobile node moves from a communication area of the first router to a communication area of the second router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is a packet to transmit as a result of the checking in step (b), the first router creating the first tunneling; And (d) the first router may forward the packet to the second router using the first tunneling, and may provide a handover method of the hybrid mobile IP using a buffer.

Advantageously, after step (d), (e) the first router checking whether a handover complete message is received from the intermediary; And (f) the first router repeats the steps (d) to (e) if the first router does not receive the result of the check in step (e), and completes the handover to the second router if received. And sending the message.

Also, the step (f) may include (f-1) when the first router receives the result of the check in the step (e), the first router checking whether a packet exists in the buffer; And (f-2) the first router forwards the packet to the second router using the first tunneling if there is a packet to be transmitted as a result of the checking in the step (f-1), and sends the hand to the second router. And transmitting the handover complete message to the second router if there is no packet to transmit.

In addition, in step (a), the first tunneling message may be received from the mobile node, and the handover completion message may be a message indicating that a second tunneling has been created between the intermediate person and the second router. Here, the second tunneling may be redirectional tunneling or bidirectional tunneling.

Here, between the steps (a) and (b), the first router further includes transmitting a second tunneling message to the intermediary requesting a second tunneling between the intermediary and the second router, or ( aa) the first router may further include transmitting a response message to the first tunneling message to the mobile node. Step (aa) may include: (aa-1) moving to a communication area of the second router without the mobile node receiving the response message; (aa-2) the mobile node retransmitting a first tunneling message requesting the first tunneling to the second router; And (aa-3) the second router sending the first tunneling message to the first router.

Or in step (a), the first tunneling message is received from the second router, and the handover complete message is moved from the mobile node to the communication area of the second router performed to the intermediary. It may be a message corresponding to a local binding update indicating completion.

In addition, the first tunneling allows the packet stored in the buffer of the first router to be forwarded to the second router, and the second tunneling forwards the packet transmitted to the first router through the intermediary to the second router. Do it.

Further, before the step (a), (A) the first router receiving a message indicating a handover from the mobile node moving from the communication area of the first router to the communication area of the second router; And (B) the first router generating and transmitting a proxy advertisement message including router information to the mobile node, wherein the router information includes new location information of the mobile node to be used in the second router. It may include a Care of Address (CoA).

In order to achieve the above objects, according to another aspect of the present invention, an intermediary for managing the local mobility of the mobile node in the communication area of the first router, the second router and the first router and the communication area of the second router. A computer-readable recording medium having recorded thereon a program for executing a handover method of a hybrid mobile IP, comprising: (a) a first tunneling between a first router and a second router; Receiving a first tunneling message requesting a request, wherein the mobile node moves from a communication area of the first router to a communication area of the second router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer of the first router; (c) if there is no packet to transmit as a result of the checking in step (b), the first router checking whether a handover complete message is received from the intermediary; And (d) if the first router does not receive the handover complete message as a result of the checking in step (c), repeats step (b) to step (c), and if received, transmits to the second router. A computer readable recording medium having recorded thereon a program for executing a handover method of a hybrid mobile IP using a buffer including transmitting the handover complete message may be provided.

In order to achieve the above objects, according to another aspect of the present invention, an intermediary for managing the local mobility of the mobile node in the communication area of the first router, the second router and the first router and the communication area of the second router. A computer-readable recording medium having recorded thereon a program for executing a handover method of a hybrid mobile IP, comprising: (a) a first tunneling between a first router and a second router; Receiving a first tunneling message requesting a request, wherein the mobile node moves from a communication area of the first router to a communication area of the second router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is a packet to transmit as a result of the checking in step (b), the first router creating the first tunneling; And (d) a computer having recorded thereon a program for executing a handover method of a hybrid mobile IP using a buffer comprising the step of forwarding the packet to the second router using the first tunneling. Recordable media can be provided.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or shown herein, can embody the principles of the present invention and invent various methods and apparatus using the same that are included in the concept and scope of the present invention. In addition, it is to be understood that all detailed descriptions, including the principles, aspects, and embodiments of the present invention, as well as listing specific embodiments, are intended to include structural and functional equivalents.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and the preferred embodiments associated with the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components as much as possible, even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Abbreviations used in the present invention are as follows, which is defined in the Internet Engineering Task Force (IETF) draft document. Hereinafter, the following abbreviations will be described.

CN: Correspondent Node

HA: Home Agent

MN: Mobile Node

CoA: Care of Address

PAR: previous access router

NAR: new access router

RtSolPr: message (router solicitation for proxy)

PrRtAdv: Proxy Router Advertisement

HI: Handover Initiate

HACK: Handover Acknowledgment

HT: Handover Terminate

FBU: Fast Binding Update

FBACK: Fast Binding Acknowledgment

FNA: Location Neighbor Advertisement

NAACK: Neighbor Advertisement Acknowledgment

2 is a view showing the overall flow of the handover method according to the present invention.

2, the handover system using a hybrid mobile IP (Hybrid Mobile IP) according to the present invention is CN / HA (200), MAP (210), PAR (220), NAR (230) and connected to the Internet MN 240 is included.

The CN / HA 200 represents a counterpart terminal (host or router) or a home agent that communicates with the MN 240.

The MAP 210 is a router of the area where the MN 240 is located and manages local mobility in the hybrid mobile IP version 6 (Hybrid MIPv6).

The PAR 220 is an access router to which the MN 240 is currently connected, and the NAR 230 is an access router in an area to which the MN 240 is to move. The PAR 220 and the NAR 230 refer to a router having a wireless interface capable of wirelessly connecting to the MN 240. Between the PAR 220 and the NAR 230, a bidirectional tunnel (BT) 260 is generated during handover.

When performing the handover according to the present invention, the packet transmitted to the MN 240 is transmitted through the following steps. First, packets destined for the MN 240 from the CN / HA 200 according to the hierarchical mobile IP are transmitted to the MAP 210 in which CoA, which is the location information of the MN 240, is registered. Packets forwarded to the MAP 210 are forwarded to the NAR 230 formed between the MAP 210 and the NAR 230 in accordance with the present invention. Here, the tunneling formed between the MAP 210 and the NAR 230 is a redirectional tunnel (RT) 250 or a bidirectional tunnel (BT). Since a bidirectional tunnel 260 is already formed between the PAR 220 and the NAR 230, a redirection tunnel 250 is preferably formed between the MAP 210 and the NAR 230. The NAR 230 transmits the forwarded packet to the MN 240 after the MN 240 is linked to the NAR 230. This solves the problems of packet delivery delay and bandwidth waste that occur during handover.

At this time, the tunnel between the MAP 210 and the NAR 230 is basically a tunnel used in the conventional hierarchical mobile IP (HMIPv6). In addition, when the MN 240 moves, a bidirectional tunnel (BT) 260 is flexibly operated between the PAR 220 and the NAR 230 according to whether or not there are MN packets in a buffer of the PAR 220. That is, if there is a packet in the buffer of the PAR 220, the BT 260 is generated and operated. If there is no packet in the buffer of the PAR 220, the BT 260 is not generated. The buffer of the PAR 220 temporarily stores a packet to be transmitted to the MN 240 whose final destination is the MN 240.

The BT 260 formed even after the handover of the MN 240 ends is not immediately destroyed. The PAR 220 may receive an HT message from the MAP 210 or a local binding update (LBU) of the MN 240 to the MAP 210 indicating that a tunneling for handover has been created between the MAP 210 and the NAR 230. Receive an HT message indicating that it has been performed. After checking the buffer of the PAR 220, the BT 260 is destroyed only when there is no packet to be delivered to the MN 240. If a packet to be transmitted remains, the BT 260 is destroyed after transmitting all remaining packets through the BT 260. This minimizes packet loss.

3 is a diagram illustrating a flow of a handover method according to an embodiment of the present invention. The handover method shown in FIG. 3 is a method in which tunneling is made between the PAR 220 and the NAR 230 before the MN 240 moves to the NAR 230. Hereinafter, it is called a predictive case.

Referring to FIG. 3, when the MN 240 moves to an overlapping communication area in step S302, the MN 240 receives a beacon signal of access points of different networks and compares power strengths. When the power strength of the access point in the communication area of the NAR 230 is strong, the RtSolPr message, which is a handover notification message indicating a handover, is transmitted to the current PAR 220 to perform the handover.

In step S304, the PAR 220 receives the message and transmits the new location information CoA (Care of Address), which is a new location information to be used in a new WLAN network, to the MN 240 by filling the PrRtAdv message, which is a proxy advertisement message.

The MN 240 that receives the PrRtAdv message in step S306 transmits an FBU message to the PAR 220 in response to the message. The FBU message is generally the last message sent to the current access router area, ie, the PAR 220, before the MN 240 performs a two-layer handover, and is a message to prepare for tunneling. The PAR 220 receiving this message prepares to forward or tunnel the packet to the NAR 230.

In this case, however, the tunnel between the PAR 220 and the NAR 230 is not created unconditionally, but only when there is a packet to be sent to the MN 240 in the buffer of the PAR 220. Subsequent to step S312 to S316 only if there is a packet to be delivered in step S324 before the PAR 220 receives an HT message from the MAP 210 indicating that tunneling between the MAP 210 and the NAR 230 has been created. Proceed. If there are no packets to be delivered to the buffer of the PAR 220, steps S312 to S316 are omitted.

If a packet exists in the buffer of the PAR 220, the flow proceeds to step S312 and the PAR 220 receives a HI message, which is a handover notification message including the new CoA and the current CoA information of the MN 240, from the NAR (the handover target). 230). In addition, packet forwarding or packet tunneling preparation is performed to send a packet having a current CoA of the MN 240 as a destination address to the NAR 230, which is a handover target.

Upon receiving the HI message in step S314, the NAR 230 checks whether a new CoA of the MN 240 is available and sends a HACK message, which is a handover response message, to the PAR 220 in response.

In step S316, bidirectional tunneling is formed between the PAR 220 and the NAR 230, and packets destined for the MN 240 existing in the buffer of the PAR 220 as the final destination are forwarded to the NAR 230 through tunneling. . At this time, the source address of the outer packet is the PAR 220 and the destination address is the NAR 230 to be handed over.

In step S310, the PAR 220 transmits a FBACK message, which is a tunneling response message, to the MN 240 in response to the FBU message, which is a tunneling message, and in step S324, the MN 240 before the HT message arrives from the MAP 210. Steps S312 to S316 are skipped if no packet to send to.

Conventionally, the PAR 220 transmits a FBACK message to the MN 240 after step S316 after tunneling is formed between the NAR 230. However, in the present invention, the PAR 220 transmits a FBACK message to the MN 240 in step S310 in order to avoid a partial reactive case which will be described in detail later with reference to FIG. 5. That is, whenever the FBU message is received from the MN 240, it is preferable to immediately transmit the FBACK message, which is a response message. This is in order to avoid this as much as possible because the operation in the PAR 220 is difficult since the partial response scheme is considerably complicated.

In step S308, the PAR 220 receives the FBU message and unconditionally transmits the FBU message to the MAP 210. This is to create unconditional tunneling between the MAP 210 and the NAR 230.

The MAP 210 proceeds to step S318 after receiving the FBU message from the PAR 220 in step S308. In step S318, the MAP 210 transmits a HI message including the new CoA and the current CoA information of the MN 240 to the NAR 230, which is a handover target. In addition, packet forwarding or packet tunneling preparation is performed to send a packet having a current CoA of the MN 240 as a destination address to the NAR 230, which is a handover target.

The NAR 230 receiving the HI message in step S320 checks whether a new CoA of the MN 240 is available and transmits a HACK message to the MAP 210 in response thereto.

In step S322, tunneling is formed between the MAP 210 and the NAR 230, and packets destined for the MN 240 delivered to the MAP 210 as the final destination are forwarded to the NAR 230 through tunneling. In this case, the source address of the outer packet is the MAP 210 and the destination address is the NAR 230 that is a handover target. In this case, the tunneling formed between the MAP 210 and the NAR 230 is redirection tunneling or bidirectional tunneling.

Thereafter, in step S324, when the tunneling between the MAP 210 and the NAR 230 is completed, the MAP 210 transmits an HT message, which is a handover completion message indicating that the handover is completed due to the completion of the tunneling to the PAR 220. do.

In step S326, the PAR 220 transmits the HT message to the NAR 230, and destroys the tunnel if a bidirectional tunnel is created between the PAR 220 and the NAR 230. However, even in this case, if a packet to be sent to the MN 240 remains in the buffer of the PAR 220, the buffer is completely empty after the transmission of the packet is completely completed and the tunnel is destroyed. The HT message is then sent to the NAR 230.

In step S328, the MN 240 performs a two-layer handover to the region of the NAR 230.

The FNA message, which is a location information notification message, is a message in which routers periodically notify their MN 240 of its CoA. The FNA message allows the MN 240 to know where it belongs.

The MN 240 may transmit the RtSol and FNA messages to the NAR 230 regardless of whether or not the FNA message is received after connecting to the corresponding access point of the NAR 230. The MN 240 transmits a message to know CoA, which is location information, from the NAR 230 side. Here, after connecting to the corresponding access point of the NAR 230, a layer 2 link up trigger occurs in the access point. The NAR 230 receiving this will replace it with an FNA message.

The NAR 230 receiving the FNA message in step S330 sends a RtAdv and NAACK message to the location information reception response message to inform the MN 240 of the availability of a new CoA. In step S332, the NAR 230 is buffered. The existing packet is sent to the MN 240.

In step S334, the MN 240 transmits an LBU message for performing local binding update to the MAP 210 and notifies that the new CoA is available. In step S336, the MAP 210 transmits an LBACK message to the MN 240, and then performs packet transmission by the general hierarchical mobile IP version 6 (HMIPv6).

4 is a diagram illustrating a flow of a handover method according to another preferred embodiment of the present invention. The handover method illustrated in FIG. 4 is a method for creating tunneling between the NAR 230 and the PAR 220 by transmitting an FBU message to the NAR 230 after the MN 240 moves to the NAR 230. In the following, it is referred to as a full reactive case.

Referring to FIG. 4, when the MN 240 moves to an overlapping communication area in step S402, the MN 240 receives a beacon signal of access points of different networks and compares power strengths. When the power strength of the access point in the communication area of the NAR 230 is strong, a message RtSolPr message indicating the handover is transmitted to the current PAR 220 to perform the handover.

The PAR 220 receiving the message in step S404 fills the PrRtAdv message with a new CoA to be used in a new WLAN network (NAR region) and transmits it to the MN 240.

Thereafter, the MN 240 moves from the PAR 220 region to the NAR 230 region and is disconnected from the PAR 220 and is connected to the NAR 230. That is, the MN 240 does not transmit the FBU message to the PAR 220 to prepare for tunneling with the NAR 230.

In step S406, the MN 240 performs a two-layer handover to the region of the NAR 230. The FNA message, which is a location information notification message, is a message in which routers periodically notify their MN 240 of its CoA. The FNA message allows the MN 240 to know where it belongs.

After connecting to the corresponding access point of the NAR 230, the MN 240 transmits RtSol and FNA messages to the NAR 230 whether or not the message is received. Here, after connecting to the corresponding access point of the NAR 230, a layer 2 link up trigger occurs in the access point. The NAR 230 receiving this will replace it with an FNA message.

The RtSol and FNA messages also include an FBU message requesting tunneling with the PAR 220. The FBU message is a message for preparing tunneling. The NAR 230 receiving the message receives the RtAdv and NAACK to the MN 240 in step S408. The message is transmitted and responded, and in step S410, the FBU message is transmitted to the PAR 220 to prepare for bidirectional tunneling between the PAR 220 and the NAR 230.

However, in this case, the tunnel between the PAR 220 and the NAR 230 is not created unconditionally. It is generated only when there are packets to be sent to the MN 240 in the buffer of the PAR 220. Subsequently, in step S422, before the PAR 220 receives the HT message from the MAP 210, the process proceeds to steps S412 to S416 only if a packet to be delivered exists in the buffer. If there are no packets to be delivered to the buffer of the PAR 220, steps S412 to S416 are omitted.

If a packet exists in the buffer of the PAR 220, the flow proceeds to step S412 and the PAR 220 transmits a HI message including information of the new CoA of the MN 240 and the current CoA to the NAR 230, which is the handover target. do. In addition, packet forwarding or packet tunneling preparation is performed to send a packet having a current CoA of the MN 240 as a destination address to the NAR 230, which is a handover target.

Receiving the HI message in step S414, NAR 230 checks whether a new CoA of MN 240 is available and sends a HACK message to PAR 220 in response.

In step S416, bidirectional tunneling is formed between the PAR 220 and the NAR 230, and packets destined for the MN 240 existing in the buffer of the PAR 220 as the final destination are forwarded to the NAR 230 through tunneling. . At this time, the source address of the outer packet is the PAR 220 and the destination address is the NAR 230 to be handed over.

In step S418, the MN 240 transmits an LBU message indicating that the local binding update has been performed to the MAP 210 and informs that the use of a new CoA is possible. In operation S420, the MAP 210 transmits an LBACK message to the MN 240 as a response message thereto.

The MAP 210 receiving the LBU message in step S422 uses the binding used in the conventional hierarchical mobile IP HMIPv6 between the MAP 210 and the NAR 230 as it is. The PAR 220 transmits an HT message indicating that the local binding update has been performed.

In step S424, the PAR 220 transmits an HT message to the NAR 230 and, if a bidirectional tunnel is created between the PAR 220 and the NAR 230, destroys the tunnel. However, even in this case, if a packet to be sent to the buffer of the PAR 220 remains, the buffer is completely empty after the transmission is completely terminated and the tunnel is destroyed. The HT message is transmitted to the NAR 230. The packet forwarding from the PAR 220 to the NAR 230 is then terminated. This is because when tunneling is generated between the MAP 210 and the NAR 230, tunneling between the PAR 220 and the NAR 230 is no longer necessary.

In operation S430, the NAR 230 receives the buffered packet from the PAR 220 and sends the buffered packet to the MN 240.

In step S432, the MAP 210 then performs packet transmission by the MN 240 and the general hierarchical mobile IP version 6 (HMIPv6).

5 is a diagram illustrating a flow of a handover method according to another preferred embodiment of the present invention. The handover method shown in FIG. 5 is similar to the prediction method shown in FIG. 3. However, when the tunneling is completed between the PAR 220 and the NAR 230 and the MN 240 moves to the NAR 230 before receiving the FBACK message, the MN 240 moves the NAR 230 to the PAR 220. It is the difference between sending the FBU message requesting tunneling between the NAR 230 and the NAR 230 again. If tunneling is generated between the PAR 220 and the NAR 230, the same operation as that of the prediction method illustrated in FIG. 3 is performed. If tunneling is not generated between the PAR 220 and the NAR 230, the tunneling is made when the FBU message is received, and the packets in the buffer of the PAR 220 are transmitted. Hereinafter referred to as a partial reactive case.

In the partial reaction mode, there are two cases: First, when the MN 240 sends the FBU message to the NAR 230, if there is already tunneling between the PAR 220 and the NAR 230, the NAR 230 does not send the FBU message to the PAR 220, Only the MN 240 recognizes that it has arrived within the communication area of the NAR 230 and forwards the forwarded packet to the MN 240.

Alternatively, if there is no tunneling between the PAR 220 and the NAR 230, the NAR 230 sends a HI message to the PAR 220 to create tunneling. However, in the present invention, since tunneling is attempted only when there is a packet to be transmitted to the MN 240 by checking the buffer of the PAR 220, the NAR 230 even if the NAR 230 is not tunneled between the PAR 220. There is no need to try tunneling in.

Referring to FIG. 5, when the MN 240 moves to an overlapping communication area in step S502, the MN 240 compares beacon signal reception and power strengths of access points of different networks. When the power strength of the access point in the communication area of the NAR 230 is strong, a message RtSolPr message indicating the handover is transmitted to the current PAR 220 to perform the handover.

The PAR 220 receiving the message in step S504 fills the PrRtAdv message with a new CoA to be used in a new WLAN network (NAR region) and transmits it to the MN 240.

The MN 240 that receives the PrRtAdv message in step S506 transmits the FBU message to the PAR 220 in response to the message. This message is generally the last message sent to the current access router area, ie, the PAR 220, before the MN 240 performs a two-layer handover and is a message to prepare for tunneling. The PAR 220 receiving this message prepares to forward or tunnel the packet to the NAR 230.

In this case, however, the tunnel between the PAR 220 and the NAR 230 is not created unconditionally, but only when there are packets to be sent from the PAR 220 to the MN 240. Subsequently, in step S524, before the PAR 220 receives the HT message from the MAP 210, the process proceeds to steps S512 to S516 only if a packet to be delivered exists in the buffer. If there are no packets to be delivered to the buffer of the PAR 220, steps S512 to S516 are omitted.

If a packet exists in the buffer of the PAR 220, the flow proceeds to step S512 and the PAR 220 transmits a HI message including information of the new CoA of the MN 240 and the current CoA to the NAR 230, which is a handover target. do. In addition, packet forwarding or packet tunneling preparation is performed to send a packet having a current CoA of the MN 240 as a destination address to the NAR 230, which is a handover target.

The NAR 230 receiving the HI message in step S514 checks whether a new CoA of the MN 240 is available and sends a HACK message to the PAR 220 in response.

In step S516, bidirectional tunneling is formed between the PAR 220 and the NAR 230, and packets destined for the MN 240 existing in the buffer of the PAR 220 as the final destination are forwarded to the NAR 230 through tunneling. . At this time, the source address of the outer packet is the PAR 220 and the destination address is the NAR 230 to be handed over.

If the packet to be sent to the MN 240 does not come before arriving in the HT message from the MAP 210 in step S524, steps S512 to S516 are omitted.

Steps S512 to S516 proceed only when a bidirectional tunnel is generated between the PAR 220 and the NAR 230.

The MN 240 does not receive the FBACK message indicating completion of the tunneling in step S510 and is disconnected from the PAR 220. Therefore, the MN 240 does not know whether tunneling is completed between the PAR 220 and the NAR 230. In step S528, when the MN 240 moves within the NAR 230 area and transmits a message, the MN 240 transmits an FBU message requesting tunneling between the PAR 220 and the NAR 230 again. The NAR 230 receives the FBU message and ignores the FBU message if tunneling is formed between the PAR 220. However, when tunneling is not formed, tunneling is formed between the PAR 220 and steps S512 to S516 are performed to receive the packet stored in the buffer of the PAR 220.

In step S508, the PAR 220 receives the FBU message and unconditionally transmits the FBU message to the MAP 210 as well.

The MAP 210 proceeds to step S518 after receiving the FBU message from the PAR 220 in step S508. In step S518, the MAP 210 transmits a HI message including information of the new CoA and the current CoA of the MN 240 to the NAR 230, which is a handover target. In addition, packet forwarding or packet tunneling preparation is performed to send a packet having a current CoA of the MN 240 as a destination address to the NAR 230, which is a handover target.

Upon receiving the HI message in step S520, the NAR 230 checks whether a new CoA of the MN 240 is available and sends a HACK message to the MAP 210 in response thereto.

In step S522, tunneling is formed between the MAP 210 and the NAR 230, and packets destined for the MN 240 delivered to the MAP 210 as the final destination are forwarded to the NAR 230 through tunneling. In this case, the source address of the outer packet is the MAP 210 and the destination address is the NAR 230 that is a handover target.

Thereafter, in step S524, the MAP 210 transmits an HT message to the PAR 220 when the redirection tunnel between the MAP 210 and the NAR 230 is completed.

In step S526, the PAR 220 transmits an HT message to the NAR 230, and if the two-way tunnel is created between the PAR 220 and the NAR 230, the tunnel is destroyed. However, even in this case, if a packet to be sent to the buffer of the PAR 220 remains, the buffer is completely empty after the transmission is completely completed and the tunnel is destroyed. The HT message is transmitted to the NAR 230.

In step S528, the MN 240 transmits the RtSol and FNA messages to the NAR 230 regardless of whether or not the message is received after connecting to the corresponding access point of the NAR 230. Here, after connecting to the corresponding access point of the NAR 230, a layer 2 link up trigger occurs in the access point. The NAR 230 receiving this will replace it with an FNA message. In addition, as described above, the FBU message is also transmitted.

The NAR 230 receiving the FNA message in step S530 transmits an RtAdv and NAACK message as a response message to inform the MN 240 of the availability of a new CoA. In step S532, the NAR 230 notifies the packet buffered in the NAR 230. Send to MN 240.

In step S534, the MN 240 transmits an LBU message to the MAP 210 and informs that a new CoA is available. In step S536, the MAP 210 transmits an LBACK message to the MN 240, and then performs packet transmission by the general hierarchical mobile IP version 6 (HMIPv6).

The prediction scheme shown in FIG. 3 and the partial response scheme shown in FIG. 5 are whether the FBU message requesting tunneling is included in the message sent when the MN 240 arrives at the NAR 230. In the partial response mode, when the NAR 230 receives the FBU message and there is no tunneling between the PAR 220 and the NAR 230 and there is a packet to be sent, tunneling is made at that time.

Accordingly, the PAR 220 preferably transmits the FBACK message as a response message to the FBU message as quickly as possible, thereby avoiding the case corresponding to the partial response method illustrated in FIG. 5.

6 is a diagram illustrating an operation algorithm of the PAR 220 according to the present invention. Receiving an FBU message does not necessarily tunnel between the PAR 220 and the NAR 230, but if there is content to be transmitted in the buffer of the PAR 220, it is transmitted by tunneling, and if there is no content to be transmitted, no tunneling is performed. If the HT message arrives without tunneling, there is no problem. If a packet to be sent to the buffer of the PAR 220 arrives before the HT message arrives, the packet is tunneled at that time to transmit the packet. Even when the HT message is received, tunneling is terminated only when there is no packet to be transmitted by checking the buffer of the PAR 220 without terminating tunneling unconditionally and transmitting the HT message to the NAR 230. This reduces signal overhead and reduces unnecessary bandwidth waste compared to unconditional tunneling. In addition, if there is a packet, the packet is transmitted through tunneling, thereby minimizing packet loss.

Referring to FIG. 6, in step S602, the PAR 220 receives an FBU message requesting tunneling. In step S604, the PAR 220 confirms whether the FBU message is from the MN 240.

If the MN 240 is correct, the process proceeds to step S606 to transmit an FBU message to the MAP 210 and proceeds to step S610.

If it is not from the MN 240, the flow advances to step S608 to check whether it is from the NAR 230, and if it is from the NAR 230, proceeds to step S610. This is the case for the Full Reactive case.

In step S610 it is checked whether the packet to be transmitted to the MN 240 in the buffer of the PAR 220.

If there is no packet, the flow proceeds to step S612 and checks whether the HT message is received from the MAP 210. When the HT message is received, the process proceeds to step S624 to transmit the HT message to the NAR 230 to terminate tunneling or forwarding. If the HT message has not been received, the process proceeds to step S610 to repeat the buffer check and the HT message reception check. Here, the HT message is a message indicating that tunneling is generated between the MAP 210 and the NAR 230. That is, since the packet to be transmitted to the MN 240 can be transmitted to the MN 240 through the MAP 210, the NAR 230, and the tunneling, the PAR 220 no longer needs the role.

If the packet exists, the flow advances to step S614. In step S614, a bidirectional tunnel is created between the PAR 220 and the NAR 230, and in step S616, the packet in the buffer is transmitted to the NAR 230. Step S616 is repeated before receiving the HT message from the MAP 210 in step S618. That is, whenever a packet is stored in the buffer, the packet is transmitted from the PAR 220 to the NAR 230 through a bidirectional tunnel.

When the HT message is received from the MAP 210 in step S618, the process proceeds to step S620 to determine whether the buffer of the PAR 220 is empty. If the buffer is empty, the process proceeds to step S624 to send an HT message to the NAR 230 and terminate the tunneling. If the buffer is not empty, the flow advances to step S622 to continue packet transmission to the NAR 230 until the buffer is empty. Finally, when the buffer becomes empty, the HT message is transmitted to the NAR 230 and tunneling ends.

In the present invention, the HT message indicating the completion of the handover is a message indicating that tunneling is generated between the MAP 210 and the NAR 230 in the prediction method of FIG. 3 or the partial response method of FIG. 5 or the MN in the complete response method of FIG. 4. The message 240 indicates that the local binding update (LBU) has been performed by the MAP 210.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

As described above, in the handover method of the hybrid mobile IP using the buffer according to the present invention, tunneling between PAR and NAR can be made to minimize packet loss while using tunneling between MAP and NAR used in FHMIPv6 as it is. .

In addition, by performing the LBU used by HMIPv6 after the MN arrives at the NAR, signal overhead or packet propagation delay may be reduced.

In addition, the present invention can only make tunneling when there is a packet to be sent between the PAR and the NAR to reduce the signal overhead and bandwidth waste used when tunneling is made.

In addition, by sending FBACK as quickly as possible to the FBU, it is possible to avoid the partial response method, which is the most complicated case, as much as possible.

In addition, even when an HT message is received, the packet loss can be minimized by checking the PAR buffer and transmitting a packet when there is a packet and destroying tunneling when there is no packet, instead of immediately destroying tunneling.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

Claims (18)

Hybrid Mobile IP including a first router, a second router, and a Mobile Anchor Point (MAP) for managing local mobility of a mobile node in a communication area of the first router and a communication area of the second router. In the handover method of IPv6), (a) the first router receiving a first tunneling message requesting first tunneling between the first router and the second router, wherein the mobile node is located from a communication area of the first router; Move to a communication area of the second router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is no packet to transmit as a result of the checking in step (b), the first router checking whether a handover complete message is received from the intermediate person; And (d) if the first router does not receive the handover complete message as a result of the checking in step (c), repeats step (b) to step (c); Sending a Handover Complete Message Handover method of hybrid mobile IP using a buffer comprising a. The method of claim 1, wherein step (d) If there is a packet corresponding to the first tunneling message in the buffer during steps (b) to (c), the first router generates the first tunneling and forwards the packet to the second router. Handover method of hybrid mobile IP using a buffer, characterized in that). In the handover method of a hybrid mobile IP including a first router, a second router and an intermediate man (MAP) for managing the local mobility of the mobile node in the communication area of the first router and the communication area of the second router, (a) the first router receiving a first tunneling message requesting first tunneling between the first router and the second router, wherein the mobile node receives the second tunnel from the communication area of the first router; Move to communication area of router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is a packet to transmit as a result of the checking in step (b), the first router creating the first tunneling; And (d) the first router forwarding the packet to the second router using the first tunneling Handover method of hybrid mobile IP using a buffer comprising a. The method of claim 2 or 3, wherein after step (d), (e) checking, by the first router, whether to receive a handover complete message from the intermediary; And (f) The first router repeats steps (d) to (e) if the first router does not receive the result of the check in step (e), and if so, the handover complete message to the second router. Step of sending Handover method of hybrid mobile IP using a buffer further comprising. The method of claim 4, wherein step (f) (f-1) when the check result is received in step (e), the first router checking whether a packet exists in the buffer; And (f-2) The first router forwards the packet to the second router using the first tunneling if there is a packet to be transmitted as a result of the checking in the step (f-1), and handovers the second router to the second router. Transmitting a completion message, and if there is no packet to transmit, transmitting the handover completion message to the second router Handover method of hybrid mobile IP using a buffer comprising a. The method of claim 1 or 3, wherein in step (a), The first tunneling message is received from the mobile node Handover method of a hybrid mobile IP using a buffer, characterized in that. 7. The method of claim 6, wherein the handover complete message is Handover method of a hybrid mobile IP using a buffer, characterized in that the message indicating that the second tunneling is generated between the intermediate and the second router. The method of claim 7, wherein the second tunneling is Handover method of a hybrid mobile IP using a buffer, characterized in that for forwarding the packet transmitted to the first router to the second router through the intermediate. The method of claim 7, wherein the second tunneling is Handover method of a hybrid mobile IP using a buffer, characterized in that the redirection tunneling (Redirectional Tunneling) or bidirectional tunneling (Bidirectional Tunneling). The method of claim 6, wherein the step (a) and (b) And transmitting, by the first router, a second tunneling message for requesting a second tunneling between the intermediate person and the second router to the intermediate person. The method of claim 6, wherein the step (a) and (b) (aa) The first router further comprises the step of transmitting a response message for the first tunneling message to the mobile node. The method of claim 11, wherein the (aa) step, (aa-1) moving the mobile node to a communication area of the second router without receiving the response message; (aa-2) the mobile node retransmitting a first tunneling message requesting the first tunneling to the second router; And (aa-3) the second router transmitting the first tunneling message to the first router Handover method of hybrid mobile IP using a buffer comprising a. The method of claim 1 or 3, wherein in step (a), And the first tunneling message is received from the second router. The method of claim 13, wherein the handover complete message is And a message corresponding to a local binding update indicating that the mobile node has completed moving to the communication area of the second router performed from the mobile node to the intermediate person. The method according to claim 1 or 3, The first tunneling is a method for handover of a hybrid mobile IP using a buffer, characterized in that to forward the packet stored in the buffer of the first router to the second router. The method according to claim 1 or 3, Before step (a) above, (A) the first router receiving a message indicating a handover from a mobile node moving from the communication area of the first router to the communication area of the second router; And (B) the first router generates a proxy advertisement message including router information and transmits the generated proxy advertisement message to the mobile node, wherein the router information includes new location information of the mobile node to be used in the second router. Include (Care of Address) Handover method of hybrid mobile IP using a buffer comprising a. A computer for executing a handover method of a hybrid mobile IP including a first router, a second router, and an intermediate man who manages local mobility of a mobile node in a communication area of the first router and a communication area of the second router. In a computer-readable recording medium recording a program, (a) the first router receiving a first tunneling message requesting first tunneling between the first router and the second router, wherein the mobile node receives the second tunnel from the communication area of the first router; Move to communication area of router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer of the first router; (c) if there is no packet to transmit as a result of the checking in step (b), the first router checking whether a handover complete message is received from the intermediary; And (d) if the first router does not receive the handover complete message as a result of the checking in step (c), repeats step (b) to step (c); A computer-readable recording medium having recorded thereon a program for executing a handover method of a hybrid mobile IP using a buffer, the method comprising transmitting a handover complete message. A computer for executing a handover method of a hybrid mobile IP including a first router, a second router, and an intermediate man who manages local mobility of a mobile node in a communication area of the first router and a communication area of the second router. In a computer-readable recording medium recording a program, (a) the first router receiving a first tunneling message requesting first tunneling between the first router and the second router, wherein the mobile node receives the second tunnel from the communication area of the first router; Move to communication area of router; (b) the first router checking whether there is a packet corresponding to the first tunneling message in a buffer; (c) if there is a packet to transmit as a result of the checking in step (b), the first router creating the first tunneling; And (d) The first router is a computer that records a program for executing a handover method of a hybrid mobile IP using a buffer, the method comprising forwarding the packet to the second router using the first tunneling. Readable record carrier.

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