KR20050091218A - Handoff system of mobile internet protocol and method thereof - Google Patents

Abstract

The present invention discloses a handoff system and method for a mobile Internet protocol based on a link state that enables stable communication by detecting a change in link state and actively copes with it, thereby improving communication service quality.

The present invention provides a link adapter for interfacing a link layer and an internet protocol layer, collecting and classifying information on the link layer to detect a change in link state, and generating link state information as a packet form link state information message from the link adapter. And a mobile internet protocol stack configured to perform communication according to an internet protocol after selecting and registering a link by determining a state of the link layer by using a message generation unit, a link status information message, and interworking with the mobile internet protocol stack. And a link state information table for storing state information of the link layer by using a link state information message.

Description

Handoff system of mobile internet protocol and method thereof

The present invention relates to a mobile internet protocol handoff system and a method thereof, and more particularly, to a mobile internet protocol handoff system which reduces communication loss by detecting a change in a link state and responds quickly. And to a method thereof.

In general, the mobile Internet protocol is proposed by the IETF so that a mobile node can seamlessly disconnect the Internet while moving the location of an access point without changing its address.

In order to prevent disconnection of Internet communication, the mobile internet protocol is a home agent, which is a router in the home network of the mobile node that stores the current location information of the mobile node, and an external network connected to the mobile node. A foreign agent acting as a default router in a foreign network and a mobile node interoperate to provide mobility.

The mobile node's unchanging address in the mobile internet protocol is called the home address, the network with the same network prefix as the home address is called the home network, and other networks except the home network are foreign. Network).

1 is a diagram illustrating a network configuration of a system for communicating using a mobile internet protocol, and a communication procedure using the mobile internet protocol will be briefly described with reference to the drawing.

First, when the mobile node 4 connects to the new external network 2, it determines whether to move itself and executes a registration process of informing the home agent 8 of the current connection location. If the registration is correct, the home agent 8 is routed to the home network 1 and intercepts the packet whose destination is the mobile node 5 and delivers it to the current location of the mobile node 5 by tunneling.

Then, if the mobile node 5 continuously changes the access network, the home agent 8 informs the home agent 8 of the new connection location through the registration process every time, and accordingly, the home agent 8 sends a packet to the new location of the mobile node. Pass to tunneling.

If the mobile node returns to its home network, it notifies the home agent 8 that it is connected to the home network 1 through a deregistration process, and stops tunneling the packet to the mobile node 7. .

Since the conventional mobile Internet protocol described above operates in the link layer L3 while enabling mobile communication in an IP-based network, the mobile internet protocol can operate independently in the link layer L2 and is ported to various access technologies such as wireless LAN and Bluetooth at low cost. It is possible.

However, due to link layer L2 independence, the conventional mobile Internet protocol has a performance problem in handoff.

In the mobile Internet protocol, a mobile node receives an agent advertisement message or a router advertisement message periodically transmitted by a router in order to determine whether the mobile node obtains its own network information and obtains network prefix information, and then obtains its home address. Compare with If the prefix obtained from the advertisement message and the prefix obtained from the home address are different, the mobile node determines that it has moved and registers according to a predetermined procedure.

However, advertising messages are broadcast to the network every few seconds. Therefore, even though the mobile node has changed its connection location, the mobile node cannot know whether to move until it receives the advertisement message. Therefore, it is not possible to inform the home agent of the new connection location, and communication is interrupted during that time.

To solve this problem, a method of obtaining information of a link directly from a mobile internet protocol and determining whether to move based on the information can be used.

However, in the above-described manner, access in the link layer should be determined by the mobile internet protocol, not by the link layer. Therefore, it is difficult to efficiently determine whether a connection is changed in the link layer, and there is a problem that may result in performance degradation.

In addition, the above method obtains link layer information through an interface depending on a specific platform or environment such as a function call. Therefore, if it is dependent on the link layer, and thus the link layer is modified or the link layer protocol is changed to another, the mobile internet protocol must also be modified. In addition, when detecting a link change to communicate, only the connection of the link layer is determined. Therefore, it is difficult to communicate using an optimal link.

In order to solve the above-mentioned problems, the present invention reduces the time that communication is lost by detecting a change in link state while registering the mobile Internet protocol while maintaining the independence of the link layer, and quickly detecting the link being connected and disconnected. There is a purpose.

In addition, the mobile Internet protocol can select a stable link to communicate based on the link state information to actively cope with changes in the communication line to improve the quality of the communication service.

In order to achieve the above object, the present invention functions as an interface between a link layer and an internet protocol layer, collects and classifies information on the link layer, and detects a change in the link layer, and a link adapter from the link adapter. Message generation unit for generating a link state information message in the form of a packet by receiving the information of the information, and the mobile terminal for communication according to the Internet protocol after selecting and registering the link by determining the state of the link layer using the link state information message And a link state information table which stores the state information of the link layer using the link state information message in association with an internet protocol stack and the mobile internet protocol stack.

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

2 is a block diagram of a handoff system of the mobile Internet protocol according to the present invention.

The handoff system of the mobile internet protocol based on the link state includes a link adapter 100, a message generator 200, a mobile internet protocol (IP) stack 300, and a link state information table 400. do. Here, the link state information table 400 is managed by predetermined link state information table management means.

The link adapter 100 serves as an interface with the link layer, collects and classifies information on the link layer, and transmits the information to the message generator 200. In addition, when the link adapter 100 detects a change in the link state by using the collected link layer information, the link adapter 100 detects the change in the link state, such as link connection (LINK_CONN), link disconnection (LINK_DISCONN), link stability (LINK_STABLE), and link instability ( LINK_UNSTABLE).

Here, the link connection (LINK_CONN) indicates that a new connection has been made, such as an unchanged connection (CONN_UNCHANGE) in which a connection formed just before, a change connection (CONN_CHANGE) in which a new connection is made, and a previous connection The association of is divided into unknown connection (CONN_UNKNOWN). At this time, if the link adapter 100 cannot determine the association with the previous connection or it is determined that it is not necessary to pass the information to the upper layer, it is classified as an unknown connection (CONN_UNKNOWN).

In addition, the link disconnection (LINK_DISCONN) indicates that the previous connection has been disconnected, and the link stability (LINK_STABLE) indicates that the packet is received at a lower rate than a predetermined error rate, and that it is possible to provide more than a predetermined bandwidth in communication performance. Instability (LINK_UNSTABLE) indicates that a packet is received at a predetermined error rate or more and can be provided at or below a predetermined bandwidth in communication performance.

For example, in the case of a mobile node whose link layer is a wireless LAN, LINK_DISCONN is a case where the power strength of the currently connected access point is lower than a threshold, and LINK_CONN is information about a new access point. Is detected and the power strength is higher than the threshold, and the connection to the new access point is established. The connection information is identified based on the link information and the unconnected connection (CONN_UNCHANGE), change connection (CONN_CHANGE), and unknown connection ( CONN_UNKNOWN) is selected. In addition, if the CRC error rate of the received frame exceeds the threshold, it is classified as link instability (LINK_UNSTABLE), and if it is below the threshold, it is classified as link stable (LINK_STABLE).

The message generator 200 generates a link state information message (LSM) in the form of a packet by using the link layer information received from the link adapter 200.

The mobile internet protocol stack 300 receives the link status information message (LSM) output from the message generator 200 and performs mobile internet communication according to the mobile internet protocol (Mobile IP).

The link state information table 400 interworks with the mobile internet protocol stack to store state information about a link. In particular, it stores an entry corresponding to each link, an IP address assigned to the link, link connection status information, and link connection quality information. Here, the link connection status information has one value of the connection (CONN) or disconnection (DISCONN), and the link connection quality information has one of the value of STABLE or UNSTABLE. CONN, DISCONN, STABLE, and UNSTALE are arbitrary integer values that do not overlap each other.

Each item of the link state information table 400 is initialized by the number of links being used by the mobile node when the mobile node is initially initialized, and then assigned one for each link. Initialization of each item sets the index for the assigned link, sets the IP address, sets the link connection status to DISCONN, and sets the link connection quality information to STABLE.

3A and 3B, the structure of the link status information message (LSM) will be described.

3A is a structural diagram of a link status information message used in an environment in which a protocol (IPv4) according to the present invention operates.

The link status information message (LSM) is transmitted using a packet type such as UDP (User digram protocol) or ICMP (Internet Control Message Protocol), and the data portion of the packet is composed of a type and a code field.

When using UDP, field values of a packet are as follows.

1) The TTL field of the IP header is set to 1.

2) The Protocol field of the IP header is set to 17 indicating UDP.

3) The source address of the IP header is set to the IP address assigned to the interface whose link status has changed.

4) The destination address of the IP header is set to the same value as the source address.

5) The source port and destination port of the UDP header are set to 434.

6) The remaining fields of the IP header and UDP header are set according to the requirements of the general IP and UDP header.

7) The Type field is set to one of integer values between 1 and 4. Each integer value represents a link connection (LINK_CONN), a link disconnection (LINK_DISCONN), a link stability (LINK_STABLE), and a link instability (LINK_UNSTABLE) in order from 1 to 4.

8) The Code field is set to one of integer values between 0 and 3, and its meaning is determined by the Type field. If the Type field is 1, it is a link connection (LINK_CONN) and the code value has a value between 1 and 3, and each integer value is in the order of 1 to 3 (CONN_UNCHANGE), change connection (CONN_CHANGE), And unknown connection (CONN_UNKNOWN). If the Type field is any other value, the Code value is set to 0 to indicate that the Code value is not used.

3B is a structural diagram of a link state information message (LSM) used in an environment in which a protocol IPv6 is operated according to the present invention.

The link status information message (LSM) is delivered in the form of a mobility header or ICMP packet used as a control message of the next generation mobile internet protocol. The data portion of the packet is a type and a code. Consists of fields. In the case of using the mobility header, field values of the packet are as follows.

1) The Next Header field of the IPv6 header is set to a value indicating a mobility header.

2) The Hop Limit of the IPv6 header is set to 1.

3) The source address of the IPv6 header is set to the IPv6 address assigned to the interface whose link state has changed.

4) The destination address of the IPv6 header is set to the same value as the source address.

5) Payload Proto value of Mobility Header is set to 59.

6) The MH Type value is set to 128.

7) The remainder of the IPv6 header and Mobility Header is set according to the requirements of the general IPv6 header and Mobility Header fields.

Hereinafter, the handoff method of the mobile Internet protocol based on the link state will be described with reference to FIGS. 4 to 9. Here, the mobile Internet protocol is divided into Mobile IPv4 and Mobile IPv6 according to the Internet protocol based on the above. FIG. 4 to FIG. 6 show an embodiment according to the case of using Mobile IPv6.

4 is a flowchart illustrating a handoff method of a mobile Internet protocol based on a link state according to an embodiment of the present invention.

First, the link adapter 100 detects a link state change by collecting and classifying state information of the link layer (S100).

The message generator 200 generates the link state information message (LSM) by processing the state information of the link layer collected in the step (S100) into a packet form and transmits the link state information message (LSM) to the mobile Internet protocol 300 (S200).

The mobile internet protocol stack 300 determines a link state by using a link status information message (LSM), selects and registers a link, and performs mobile internet communication according to mobile internet protocol (Mobile IP) (S300).

The link state information table 400 interoperates with the mobile internet protocol stack and stores state information about the link (S400).

5 to 9 illustrate packet inspection and packet processing operations of the mobile internet protocol stack 300 after receiving a link status information message (LSM) from the message generator 200. Parts not described are basic movements. Follow the Internet protocol.

5 is a detailed flowchart of an operation S300 of checking a link state information message of FIG. 4.

When the mobile internet protocol stack 300 receives a packet from the message generator 200 (S501), it is determined whether the packet is a link state information message (LSM) (S502), and the packet is a link state information message (LSM). If not, the packet is processed according to the procedure of the general mobile internet protocol (S503).

On the other hand, if the packet is a link status information message (LSM), it is determined whether the source address and the destination address of the packet are the same and whether the packet is the IP address used by the mobile node (S504). As a result of the determination in step S504, if the source address and the destination address of the packet are not the same or not the IP address used by the mobile node, the packet processing is terminated (S505), and the source and destination addresses of the packet are the same or the mobile node is the same. If the IP address to be used is correct, the TTL value or the hop limit value is 1 (S506). If the TTL value or the hop limit value is not 1, the packet processing is terminated (S505). If the TTL value or the hop limit value is 1, it is checked whether the type value and the code value are valid values (S507). Through the steps S505 to S507, it is checked whether the packet is the correct packet to minimize the possibility of a malicious external node attacking the mobile node.

6 to 9 are flowcharts illustrating packet processing for each type of link state information message of FIG. 4.

If it is determined that the packet received through the steps S501 to S507 of FIG. 5 is a correct link state information message, the packet processing procedure of the next step is performed according to the type value of the received link state information message.

First, FIG. 6 is a flowchart illustrating a packet processing method when a type value of a link state information message checked by the mobile internet protocol stack 300 is a link connection LINK_CONN.

If the type value of the link status information message is a link connection (LINK_CONN) (S601), the link status table item of the link using the destination address obtained from the link status information message is retrieved from the link status information table 400, The IP addresses of the link state information table entries are compared with the destination address of the link state information message to search for a match (S602).

If a matching link state information table item cannot be found from the link state information table 400 in step S602, a new item corresponding to the link is created and initialized (S603). On the other hand, when setting the link index and IP address of the newly created link status information table entry, if the corresponding link cannot be found or the IP address cannot be found, the entry is deleted and the processing of the received packet is finished.

If there is a matching link state information table item in step S602, the link connection state of the item is updated to connection CONN (S604). After updating, check the code value (S605) and if the code value is change connection (CONN_CHANGE) or unknown connection (CONN_UNKNOWN), send a router solicitation message to the corresponding link. At step S606, the router on the link sends a Router Advertisement message and completes the processing at step S607.

FIG. 7 is a flowchart illustrating a packet processing method when the type value of the link status information message checked by the mobile internet protocol stack 300 is LINK_DISCONN.

If the type value of the link status information message checked by the mobile internet protocol stack 300 is link disconnection (LINK_DISCONN) (S701), the link status table entry of the link using the destination address obtained from the link status information message is selected. By searching from the link state information table 400, it is determined whether or not the IP addresses of the link state information table items match with the destination address of the link state information message (S702).

If a matching link state information table entry cannot be found from the link state information table 400 in step S702, the packet processing ends (S706).

On the other hand, if a matching link state information table item is found from the link state information table 400 in step S702, the link connection state of the item is updated to DISCONN (S703), and the link state information table In step 400, the link connection state is searched for items having a connection (CONN), and it is determined whether there is a registered link among the searched items (S704).

As a result of the determination, if the registered link state information table entry exists, the packet processing procedure is terminated (S706). If not, the registration is started by selecting an item whose link connection state is CONN (S705). When selecting the link state information table item, the link connection quality information is STABLE has priority, and one of the items having the same link connection quality can be arbitrarily selected. Here, the registration process follows the mobile Internet protocol, and when the registration is completed (S706).

8 is a flowchart illustrating a packet processing method when the type value of the link status information message checked by the mobile internet protocol stack 300 is LINK_STABLE.

If the type value of the link status information message is LINK_STABLE (S801), the link status table item of the link using the destination address obtained from the link status information message is retrieved from the link status information table 400, The IP addresses of the link state information table entries are compared with the destination address of the link state information message to search for a match (S802).

If a matching link state table item cannot be found from the link state table 400 in step S802, the packet processing ends (S807).

On the other hand, if a matching link state information table item is retrieved from the link state information table 400 in step S802, it is determined whether the link connection state of the item is CONN (S803), and the link connection state is If the connection is not CONN, packet processing is terminated (S807). If the link connection state is the connection CONN, the link connection quality is updated to STABLE (S804).

The link status information table 400 searches for items whose link connection status is CONN and the link connection quality is STABLE, and determines whether there is a registered link among the searched items (S805).

As a result of the determination, if there is a registered link, the packet processing procedure is terminated (S807). If not, the previously completed registration is deregulated and the link connection state is CONN and the link connection quality information is stable ( STABLE) selects and registers any one link having the link state information table item (S806) and finishes the packet processing procedure (S807).

FIG. 9 is a flowchart illustrating a packet processing method when a type value of a link state information message checked by the mobile Internet protocol stack 300 is LINK_UNSTABLE.

If the type value of the link status information message is LINK_UNSTABLE, the link status table item of the link using the destination address obtained from the link status information message is searched from the link status information table 400, The IP addresses of the link status information table entries are compared with the destination address of the link status information message to search for a match (S902).

If a matching link state information table entry cannot be found from the link state information table 400 in step S902, the packet processing ends (S903).

On the other hand, if a matching link state information table item is found from the link state information table 400 in step S902, it is determined whether the link connection state of the item is connection (CONN) (S904), and the link connection state is If the connection is not CONN, packet processing is terminated (S903). If the link connection status is CONN, the link connection quality is updated to UNSTABLE (S905).

The link status information table 400 searches for items in which the link connection status is CONN and the link connection quality is stable, and determines whether there is a registered link among the searched items (S906).

As a result of the determination, if there is a registered link, the packet processing procedure is terminated (S909). If the link is not present, a link state information table item whose link connection state information is CONN and link connection quality information is STABLE is found. In step S907, the link index of the item is registered as a link (CONN) and the link connection quality is stable (STABLE) from the link index (S908), and the packet processing procedure is completed (S909).

At this time, the registration process is carried out according to the mobile Internet protocol. If there is a link that has already been registered, the registration process is first performed after registering the link.

Thereafter, the four types of link status information messages checked by the mobile Internet protocol stack 300 are the link types LINK_CONN, LINK_DISCONN, LINK_STABLE, and links. If the value is not one of LINK_UNSTABLE, the packet is discarded and the packet processing is terminated.

The above embodiment shows that Mobile IPv6 is used as the mobile Internet protocol, but by replacing the Router Solicitation message with an Agent Solicitation message and using Mobile IPv4 as the mobile Internet protocol. It is also applicable when using Mobile IPv4.

As described above, the present invention collects the information transmitted from the link layer and detects the change in the link state connected / disconnected according to the movement of the mobile node, thereby quickly detecting the movement of the mobile node to improve the quality of the communication service. It is effective to improve.

In addition, regardless of the type of link layer through the mobile Internet protocol stack, the mobile Internet protocol can communicate according to the Internet protocol regardless of the type of the link layer, so that it can be developed or ported quickly and at low cost. .

In addition, by detecting a change in the link connection quality of the link layer to select a link having a good connection quality to communicate, there is an effect that enables more stable communication.

1 is a network diagram of a system for communicating using a general mobile Internet protocol.

2 is a block diagram of a handoff system of the mobile Internet protocol according to the present invention;

3A is a structural diagram of a link status information message used in the Internet Protocol (IPv4) according to the present invention.

3B is a structural diagram of a link status information message used in the Internet Protocol (IPv6) according to the present invention.

4 is a flowchart illustrating a handoff method of a mobile Internet protocol according to an embodiment of the present invention.

5 is a detailed flowchart of a method of checking a link state information message of FIG. 4.

6 to 9 are flowcharts illustrating packet processing for each type of link state information message of FIG. 4.

Claims (17)

A link adapter which functions as an interface between a link layer and an internet protocol layer, collects and classifies information on the link layer, and detects a change in the link layer; A message generator configured to receive the link layer information from the link adapter and generate a link state information message in a packet form; A mobile internet protocol stack configured to determine a state of the link layer by using the link state information message, select and register a link, and perform communication according to an internet protocol; And Link state information table management means interworking with the mobile internet protocol stack to store state information of the link layer using the link state information message; Handoff system of the mobile Internet protocol, characterized in that configured to include. The method of claim 1, wherein the link adapter, And changing the link layer into one of a link connection state, a link disconnection state, a link stability state, and a link instability state. The method of claim 2, wherein the link connection state is an unconnected connection re-connected with the previous connection formed immediately before, a change connection made with a new connection different from the previous connection, and an association with the previous connection. Handoff system of Mobile Internet Protocol, characterized in that classified as one of the unknown connection. The handoff system of claim 1, wherein the link state information table stores an item for each link, an IP address assigned to the link, link connection state information, and link connection quality information. 5. The handoff system according to claim 4, wherein the link connection state information is stored as a non-duplicate integer value representing during connection and disconnection. The handoff system of claim 4, wherein the link connection quality information is stored as a non-overlapping integer value representing stability and instability. The method of claim 1, wherein the link status information message is included in a type field and a code field of a packet format of a user digram protocol (UDP), an Internet control message protocol (ICMP), and a mobility header. And handing off the link state information. A first step of detecting and changing a link state by collecting and classifying link state information from the link layer; A second step of processing the link state information into a packet to generate a link state information message and to transmit it to an internet protocol layer; And  And determining a link state by using the link state information message, and selecting and registering a link. The method of claim 8, wherein the link status information message is included in a Type field and a Code field of a packet format of a User Digram Protocol (UDP), an Internet Control Message Protocol (ICMP), and a Mobility Header. And handing off the link state information. The method of claim 8, wherein between the second step and the third step, And examining the link status information message. The method of claim 10, wherein the checking of the link status information message comprises: Receiving a packet to determine whether the packet is a link status information message; If the packet is a link status information message, determining whether the source address and the destination address of the packet are the same and whether the packet is an IP address used by the mobile node; If the source address and the destination address of the packet are the same or the IP address used by the mobile node is correct, determining whether a TTL value or a hop limit value is 1; And Checking whether a type value and a code value are valid values when the TTL value or the hop limit value is 1; and a handoff method of a mobile internet protocol, comprising: . The method as claimed in claim 8, wherein the type value of the link status information message of step 3 is a value indicating a link connection status. Retrieving and creating a link state information table item using a destination address of the link state information message; Updating the link connection state of the item to a connected state when the link state information table item is found; And Checking a code value of the link status information message and sending a router solicitation message to a link corresponding to the link status information message according to a code value; Handoff method of mobile internet protocol. The method as claimed in claim 8, wherein the type value of the link status information message of step 3 is a value indicating a link disconnection state. Retrieving a link state table entry of a link using a destination address of the link state information message; Updating the link connection state of the item to the disconnected state if the link state information table item exists; And Searching for the items in which the link connection state is in a connected state, and first selecting and registering a link in which the link connection quality information is stable among the searched items; Off way. The method of claim 8, wherein the type value of the link status information message of the third step is a value indicating a link stability state. Retrieving a link state table entry of a link using a destination address obtained from the link state information message; Determining whether a link connection state of the item is in a connected state when the link state information table item is found; Updating the link connection quality to a stable state if the link connection state is a connected state; Checking whether a link having a link state information table item in which the link connection state information is in a connected state and the link connection quality information is in a stable state; And If the link does not exist, cancel the previously completed registration and select and register any one link having a link state information table item in which the link connection state information is in a connected state and the link connection quality information is in a stable state. Handoff method of the mobile Internet protocol comprising a. The method of claim 8, wherein the type value of the link status information message of the step 3 is a value indicating a link instability state. Retrieving a link state table entry of a link using a destination address obtained from the link state information message; Determining whether a link connection state of the item is in a connected state when the link state information table item is found; Updating the link connection quality to an unstable state when the link connection state is a connected state; Checking that a link is registered and has a link state in which the link connection state is in a connected state and the link connection quality is in a stable state; If a corresponding link does not exist as a result of the checking, checking whether a link having a link state information table item in which the link connection state information is in a connected state and the link connection quality information is in a stable state exists; And If a corresponding link exists as a result of the inspection, the previously completed registration is released, and any one link having a link state information table item in which the link connection state information is in a connected state and the link connection quality information is in a stable state. Selecting and registering the mobile internet protocol. The method of claim 8, wherein the link state change is classified into one of a link connection state, a link disconnection state, a link stability state, and a link instability state. 17. The method of claim 16, wherein the link connection state is an unchanged connection state that is reconnected with a previous connection that was formed immediately before, a change connection state where a new connection is different from the previous connection, and an association with the previous connection. A method for handoff of a mobile internet protocol, characterized by being classified as one of an unknown unknown connection state.