JP3810711B2 - Packet transfer method, packet transfer system, and computer program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packet transfer method and packet transfer system in a mobile IP network, and a computer program for realizing the packet transfer system using a computer.
[0002]
[Prior art]
Conventionally, in an environment where packet communication is performed using TCP (Transmission Control Protocol) and IP (Internet Protocol), even if a terminal moves from a currently connected network to a different network, it is a method for continuing a session. “Mobile IP” has been standardized. The mobile IP network conforming to the mobile IP is composed of a plurality of IP networks (areas), and the mobile terminal moves appropriately in each area. A “home network” is defined as an area to which the mobile terminal originally belongs, and is distinguished from other networks in the mobile IP network (hereinafter referred to as external networks). An address on the home network (home IP address) is assigned in advance to the mobile terminal. When moving to an external network, an address (external IP address) on the external network is temporarily assigned to the mobile terminal that has moved.
[0003]
On the home network, a mobility agent device (home agent; HA) that performs location management and packet transfer of a mobile terminal originally belonging to the home network is arranged. This home agent has a location management table that stores a home IP address and an external IP address in association with each other for a mobile terminal that has moved to an external network. When a packet addressed to a mobile terminal in the external network arrives at the home network, the home agent searches the location management table and transfers the arrival packet to the corresponding external IP address. The home agent registers the corresponding home IP address and external IP address in the location management table in response to a location registration request from a mobile terminal in the external network.
[0004]
Further, in individual networks (home network and external network) in the mobile IP network, data (IP packet) is used by using a MAC (Media Access Control) address in an Ethernet (registered trademark) frame communicated on the LAN. Communication. FIG. 7 shows the configuration of an Ethernet (registered trademark) frame. FIG. 8 shows the configuration of an Ethernet (registered trademark) header included in the frame of FIG. FIG. 9 shows the configuration of the IP header included in the IP packet. When an IP packet arrives from the outside such as the Internet, the router located at the entrance / exit of the home network has a destination MAC address and a source MAC address (router) when the arrival IP packet has a destination IP address in the home network. The incoming IP packet is output into the home network according to the frame configuration of FIG. The association between the destination MAC address and the destination IP address is registered in an ARP (Address Resolution Protocol) table. When a packet arrives from the outside, the router searches the ARP table and acquires the corresponding destination MAC address. In the ARP table, the MAC address of the home agent is registered instead as the MAC address of the mobile terminal in the external network. This registration is performed by the home agent in response to a location registration request from a mobile terminal in the external network.
[0005]
Therefore, when the packet addressed to the mobile terminal in the external network arrives, the router searches the ARP table, acquires the MAC address of the home agent as the destination MAC address, and sets the arrival packet in the home network according to the frame configuration of FIG. Output to. As a result, the home agent receives the arrival packet, searches the location management table to acquire the corresponding external IP address, encapsulates the arrival packet, and transfers it to the mobile terminal in the external network.
[0006]
[Problems to be solved by the invention]
However, in the conventional packet transfer method described above, there is a problem that it takes time to perform both the ARP table search and the location management table search when transferring a packet from the home network to the mobile terminal in the external network. is there. Generally, a router is equipped with hardware dedicated to ARP table search, and high-speed search is possible. However, since a home agent is realized by software using a general-purpose computer (such as a personal computer), it takes time to search. Take it. In particular, when the number of registrations in the location management table is large, the influence becomes large.
[0007]
The present invention has been made in view of the above-described circumstances, and can reduce the time required for searching a location management table when transferring a packet from a home network to a mobile terminal in an external network in a mobile IP network. It is possible to provide a packet transfer method and a packet transfer system that can reduce the time required for the packet transfer.
[0008]
Another object of the present invention is to provide a computer program for realizing the packet transfer system using a computer.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the packet transfer method according to claim 1 is a mobile IP network composed of a home network and an external network, wherein a mobile terminal originally belonging to the home network is in the external network, A packet transfer method for transferring an arrival IP packet from the home network to the external network when an IP packet destined for a home IP address assigned to the mobile terminal arrives at the home network, The process of registering the external IP address of the external network assigned to the mobile terminal and the home IP address in association with each other in the location management table, and the MAC address used for IP packet transfer in the home network as the location Management A process of generating a unique proxy MAC address in the home network, a process of associating and registering the proxy MAC address and the home IP address in the ARP table, and based on the ARP table The process of obtaining the arrival IP packet forwarded to the proxy MAC address in the home network by the proxy MAC address, and the corresponding item of the location management table from the index included in the proxy MAC address The method includes a step of acquiring an external IP address and a step of transferring the arrival IP packet to the acquired external IP address.
[0010]
In order to solve the above problem, the packet transfer system according to claim 2 is a mobile IP network composed of a home network and an external network, wherein a mobile terminal originally belonging to the home network exists in the external network, A packet forwarding system for forwarding an incoming IP packet from the home network to the external network when an IP packet destined for a home IP address assigned to the mobile terminal arrives at the home network, The location management table that stores the external IP address of the external network assigned to the mobile terminal in association with the home IP address, and the location management as a MAC address used for IP packet transfer in the home network Registration means for generating a proxy MAC address unique to the home network and registering the proxy MAC address in the ARP table in association with the home IP address, based on the ARP table The arrival IP packet forwarded in the home network to the proxy MAC address is acquired by the proxy MAC address, and the external IP address of the corresponding item in the location management table is obtained from the index included in the proxy MAC address. And transferring means for transferring the arrival IP packet to the acquired external IP address.
[0011]
In order to solve the above problem, the computer program according to claim 3 is a mobile IP network composed of a home network and an external network, wherein a mobile terminal originally belonging to the home network is in the external network, and A computer program for performing packet transfer processing for transferring an incoming IP packet from the home network to the external network when an IP packet destined for the home IP address assigned to the mobile terminal arrives at the home network And a process of associating the external IP address of the external network assigned to the mobile terminal with the home IP address and registering it in the location management table, and used for IP packet transfer within the home network. A MAC address including an index of the location management table item and generating a unique proxy MAC address in the home network, and registering the proxy MAC address and the home IP address in association with each other in the ARP table Processing, processing for obtaining the arrival IP packet forwarded in the home network addressed to the proxy MAC address based on the ARP table by the proxy MAC address, and the index included in the proxy MAC address It is characterized in that the computer executes processing for acquiring an external IP address of a corresponding item in the location management table and processing for transferring the arrival IP packet to the acquired external IP address.
As a result, the above-described packet transfer system can be realized using a computer.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of a mobile IP network 10 to which a packet transfer system according to an embodiment of the present invention is applied. The mobile IP network 10 includes a home network 4a and an external network 4b, which are general IP networks. The home network 4a and the external network 4b communicate data (IP packets) using a MAC (Media Access Control) address in an Ethernet (registered trademark) frame (see FIGS. 7 and 8) communicated on the LAN. Do.
[0013]
The MAC address is an address unique to a network interface device that is connected to a LAN (home network 4a, external network 4b, etc.) and inputs and outputs packets. The MAC address includes a global address given at the time of manufacturing the network interface device and a private address that can be arbitrarily set in the LAN. The MAC address is composed of 48 bits, and a value in which the most significant 2 bits in the 48 bits are “01” is a private address. Therefore, by referring to these 2 bits, it is possible to determine whether the address is a private address or a global address. For example, the hexadecimal number “40: 00: 00: 00: 00: 00” is one of the private addresses. However, “:” is a notation for convenience to indicate a boundary every 8 bits.
[0014]
The home network 4a includes a mobile terminal 1a originally belonging to the home network 4a, a mobility agent device (hereinafter referred to as home agent; HA) 2a that performs location management and packet transfer of the mobile terminal 1a, and an entrance / exit of the home network 4a Is connected to the router 3a.
The mobile terminal 1a is, for example, a portable personal computer (notebook PC) or a personal digital assistant (PDA). Each mobile terminal 1a is previously assigned an address (home IP address) on the home network 4a. As shown in FIG. 1, when the mobile terminal 1a moves to the external network 4b, an address (external IP address) on the external network 4b is temporarily assigned.
[0015]
The home agent 2a includes a general-purpose computer (such as a personal computer) and a computer program executed on the computer, and a location management table 21 is stored in the storage device. The location management table 21 stores the home IP address of the mobile terminal 1a that has moved to the external network 4b and the external IP address in association with each other. FIG. 5 shows a configuration example of the location management table 21. As shown in FIG. 5, in the location management table 21, a home IP address and an external IP address are set in association with each other, and an index is set for each item.
[0016]
The router 3a is connected to the Internet 8, and transmits and receives IP packets transferred between the home network 4a and the Internet 8. The router 3 a has an ARP (Address Resolution Protocol) table 31. Each device (mobile terminal 1a, home agent 2a, etc.) on the home network 4a also has an ARP table 31 (not shown). The ARP table 31 stores the home IP address and MAC address of each device (such as the mobile terminal 1a and the home agent 2a) on the home network 4a in association with each other. FIG. 6 shows a configuration example of the ARP table 31. As shown in FIG. 6, in the ARP table 31, a home IP address and a MAC address are set in association with each other.
[0017]
Also, connected to the external network 4b are a mobile terminal 1a originally belonging to the home network 4a, a mobility agent device (hereinafter referred to as “FA”) 2b, and a router 3b located at the entrance / exit of the external network 4b. ing. The external agent 2b manages the mobile terminal 1a that has moved from the home network 4a, and performs packet transfer between the external network 4b and the home network 4a related to the mobile terminal 1a. The router 3b is connected to the Internet 8, and sends and receives IP packets transferred between the external network 4b and the Internet 8.
The terminal 9 is connected to the Internet 8 and performs IP packet communication.
[0018]
Next, in the mobile IP network 10 of FIG. 1, when an IP packet addressed to the mobile terminal 1a in the external network 4b arrives at the home network 4a, the arrival IP packet is transferred from the home network 4a to the external network 4b. The operation | movement which performs is demonstrated with reference to FIGS. 2 to 4 are first to third sequence charts showing the flow of packet transfer processing in the mobile IP network 10.
[0019]
First, with reference to FIG. 2, a location registration process performed when the mobile terminal 1a originally belonging to the home network 4a moves to the external network 4b will be described. In FIG. 2, the mobile terminal 1a that has moved to the external network 4b (hereinafter referred to as the external mobile terminal 1a) notifies the home agent 2a of an RRQ (Registration Request) message by IP packet for location registration (step S11). . This RRQ message includes the external IP address on the external network 4b assigned to the external mobile terminal 1a.
[0020]
Thereby, the home agent 2a acquires the external IP address of the external mobile terminal 1a and registers it in the location management table 21 in association with the home IP address of the external mobile terminal 1a as shown in FIG. Step S12). Here, the home agent 2 a assigns an index to the registered item and sets it in the location management table 21. In this example, for convenience of explanation, it is assumed that the home IP address of the external mobile terminal 1a is “192.168.0.5”, the external IP address is “172.70.10.2”, and the index is “9”.
[0021]
The IP packet including the RRQ message is transferred via the foreign agent 2b, and the foreign agent 2b acquires and manages information such as the home IP address of the external mobile terminal 1a.
[0022]
Next, the home agent 2a distributes an item deletion request (Gratuitous ARP) related to the external mobile terminal 1a in the ARP table 31 to the home network 4a by the broadcast method (step S13). Thereby, each device on the home network 4a such as the router 3a deletes the item related to the external mobile terminal 1a from its own ARP table 31 (step S14). The home agent 2a transfers an RRP (Registration Reply) message by IP packet to the external mobile terminal 1a via the external agent 2b and notifies the completion of location registration (step S15).
[0023]
2, the home IP address “192.168.0.5” and the external IP address “172.70.10.2” of the external mobile terminal 1a are stored in the location management table 21 in the home network 4a as shown in FIG. It is set in association with the index “9”. In addition, items relating to the external mobile terminal 1 a are deleted from the ARP table 31.
[0024]
Next, referring to FIG. 3, after the location registration process of FIG. 2, the ARP table registration process performed when the first IP packet addressed to the external mobile terminal 1a arrives at the home network 4a via the Internet 8 is performed. explain. Hereinafter, a case where the terminal 9 not belonging to the mobile IP network 10 transmits an IP packet to the external mobile terminal 1a will be described as an example.
[0025]
In FIG. 3, the terminal 9 transmits an IP packet with the home IP address “192.168.0.5” of the external mobile terminal 1a as the destination IP address (step S21). In the home network 4a, when this IP packet arrives, the router 3a searches its own ARP table 31 based on the home IP address that is the destination IP address of the arrival IP packet (step S22).
[0026]
In this search, since the corresponding item has been deleted by the location registration process of FIG. 2, the MAC address corresponding to the destination home IP address cannot be found. Therefore, the router 3a distributes the MAC address search request (ARP Request) corresponding to the destination home IP address to the home network 4a by the broadcast method (step S23).
[0027]
Upon receiving this “ARP Request” message, the home agent 2a searches the location management table 21 in FIG. 5 and searches the index “of the item of the home IP address“ 192.168.0.5 ”to be searched (item related to the external mobile terminal 1a). 9 "is acquired (step S24). Next, the home agent 2a generates a MAC address that includes the index “9” and is unique within the home network 4a using a private address. For example, the index “9” is arranged at the lower bit position, for example, the lower 8 bits, and the private address of the hexadecimal number “40: 00: 00: 00: 00: 09” is generated. Then, the home agent 2a notifies the router 3a of this private address (hereinafter referred to as a proxy MAC address) (step S25). As a result, the router 3a associates the notified proxy MAC address “40: 00: 00: 00: 00: 09” with the home IP address “192.168.0.5” to be searched, and ARP as shown in FIG. Register in the table 31 (step S26).
[0028]
Next, the router 3a forwards the incoming IP packet to the proxy MAC address in the home network 4a (step S27). The home agent 2a acquires the arrival IP packet with the proxy MAC address “40: 00: 00: 00: 00: 09”, and the external IP address “172.70.” Corresponding to the index “9” included in the proxy MAC address. 10.2 "is acquired from the position management table 21 of FIG. 5 (step S28). Next, the home agent 2a transmits an IP packet encapsulating the arrival IP packet with the acquired external IP address as the destination IP address (step S29). As a result, the encapsulated IP packet is transferred to the external mobile terminal 1a, and the IP packet transmitted from the terminal 9 reaches the external mobile terminal 1a.
[0029]
By the ARP table registration process of FIG. 3, the ARP table 31 in the home network 4a has the home IP address “192.168.0.5” and the proxy MAC address “40:00:00” of the external mobile terminal 1a as shown in FIG. : 00: 00: 09 "is set in association.
[0030]
Next, referring to FIG. 4, after the ARP table registration process of FIG. 3, the packet transfer process performed when the IP packet addressed to the external mobile terminal 1a arrives at the home network 4a from the terminal 9 via the Internet 8 is performed. explain. In FIG. 4, the terminal 9 transmits an IP packet with the home IP address “192.168.0.5” of the external mobile terminal 1a as the destination IP address (step S31). In the home network 4a, when this IP packet arrives, the router 3a searches its own ARP table 31 shown in FIG. 6 based on the home IP address that is the destination IP address of the arrival IP packet (step S32).
[0031]
When the proxy MAC address “40: 00: 00: 00: 00: 09” corresponding to the destination home IP address “192.168.0.5” is acquired from the ARP table 31 by this search, the router 3a addresses the proxy MAC address. The incoming IP packet is transferred into the home network 4a (step S33). Next, the home agent 2a acquires the arrival IP packet from the proxy MAC address “40: 00: 00: 00: 00: 09”, and the external IP corresponding to the index “9” included in the proxy MAC address. The address “172.70.10.2” is acquired from the location management table 21 of FIG. 5 (step S34). Then, using the acquired external IP address as the destination IP address, an IP packet encapsulating the arrival IP packet is transmitted, so that the IP packet transmitted from the terminal 9 reaches the external mobile terminal 1a ( Step S35).
[0032]
As described above, in the packet transfer process of FIG. 4, the home agent 2a uses the external IP address of the external mobile terminal 1a that is the transfer destination of the IP packet transmitted from the terminal 9 as an index included in the proxy MAC address. Based on the location management table 21 directly. Therefore, the search of the location management table 21 is not executed. As a result, it is possible to reduce the time required for the location management table search when transferring a packet from the home network 4a to the external mobile terminal 1a, and the time required for the packet transfer can be reduced.
[0033]
In the above-described embodiment, the private address serving as the proxy MAC address is generated by arranging the index of the position management table 21 in the lower bit position. However, the arrangement position of the index is an available predetermined position in the private address. If it is.
[0034]
In the above-described embodiment, the home agent 2a corresponds to a registration unit and a transfer unit.
[0035]
Also, a program for realizing each step performed by the home agent 2a shown in FIGS. 2 to 4 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. By doing so, packet transfer processing may be performed. Here, the “computer system” may include an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system.
[0036]
Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.
[0037]
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.
[0038]
【The invention's effect】
As described above, according to the present invention, in a mobile IP network composed of a home network and an external network, a mobile terminal originally belonging to the home network exists in the external network and is assigned to the mobile terminal (external mobile terminal). When an IP packet destined for the home IP address arrived at the home network, the external IP address of the external mobile terminal to which the incoming IP packet is transferred is based on the index included in the proxy MAC address Can be obtained directly from the location management table. As a result, it is possible to reduce the time required for searching the location management table when transferring a packet from the home network to the external mobile terminal, and the time required for the packet transfer can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a mobile IP network 10 to which a packet transfer system according to an embodiment of the present invention is applied.
FIG. 2 is a first sequence chart showing a flow of packet transfer processing in the mobile IP network 10 shown in FIG.
FIG. 3 is a second sequence chart showing a flow of packet transfer processing in the mobile IP network 10 shown in FIG. 1;
FIG. 4 is a third sequence chart showing a flow of packet transfer processing in the mobile IP network 10 shown in FIG. 1;
FIG. 5 is a diagram showing a configuration example of a location management table 21.
6 is a diagram showing a configuration example of an ARP table 31. FIG.
FIG. 7 is a diagram illustrating a configuration of an Ethernet (registered trademark) frame.
FIG. 8 is a diagram illustrating a configuration of an Ethernet (registered trademark) header.
FIG. 9 is a diagram illustrating a configuration of an IP header.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a ... Mobile terminal, 2a ... Mobility agent apparatus (home agent; It calls HA), 2b ... Mobility agent apparatus (foreign agent; FA), 3a, 3b ... Router, 4a ... Home network, 4b ... External network, 8 ... Internet , 9 terminal, 10 mobile IP network, 21 location management table, 31 ARP table

Claims (3)

In a mobile IP network composed of a home network and an external network, a mobile terminal originally belonging to the home network exists in the external network, and an IP packet destined for a home IP address assigned to the mobile terminal A packet transfer method for transferring the arrival IP packet from the home network to the external network when arriving at the network,
Registering the external IP address of the external network assigned to the mobile terminal and the home IP address in association with each other in the location management table;
Generating a proxy MAC address unique to the home network including an index of an item of the location management table as a MAC address used for IP packet transfer in the home network;
Associating the proxy MAC address with the home IP address and registering them in the ARP table;
Obtaining the arrival IP packet forwarded in the home network to the proxy MAC address based on the ARP table by the proxy MAC address;
Obtaining an external IP address of a corresponding item in the location management table from an index included in the proxy MAC address;
Transferring the incoming IP packet to the acquired external IP address;
A packet transfer method comprising: In a mobile IP network composed of a home network and an external network, a mobile terminal originally belonging to the home network exists in the external network, and an IP packet destined for a home IP address assigned to the mobile terminal A packet forwarding system for forwarding the incoming IP packet from the home network to the external network when arriving at the network;
A location management table for storing the external IP address of the external network assigned to the mobile terminal and the home IP address in association with each other;
As a MAC address used for IP packet transfer in the home network, a proxy MAC address including an index of the location management table item and unique in the home network is generated, and the proxy MAC address is generated as the home IP address. Registration means for registering in the ARP table in association with
The arrival IP packet forwarded in the home network to the proxy MAC address based on the ARP table is acquired by the proxy MAC address, and the corresponding position management table is obtained from an index included in the proxy MAC address. Transfer means for acquiring an external IP address of an item to be transmitted and transferring the arrival IP packet to the acquired external IP address;
A packet transfer system comprising: In a mobile IP network composed of a home network and an external network, a mobile terminal originally belonging to the home network exists in the external network, and an IP packet destined for a home IP address assigned to the mobile terminal A computer program for performing packet transfer processing for transferring the arrival IP packet from the home network to the external network when arriving at the network,
A process of registering the external IP address of the external network assigned to the mobile terminal and the home IP address in association with each other in the location management table;
A process for generating a proxy MAC address unique to the home network including an index of the location management table item as a MAC address used for IP packet transfer in the home network;
A process of associating the proxy MAC address with the home IP address and registering them in the ARP table;
A process of acquiring the arrival IP packet transferred in the home network to the proxy MAC address based on the ARP table by the proxy MAC address;
A process of acquiring an external IP address of a corresponding item in the location management table from an index included in the proxy MAC address;
A process of forwarding the arrival IP packet to the acquired external IP address;
A computer program for causing a computer to execute.

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