JP2002290445A - Automatic switching method for communication interface and its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute switching of a communication interface to a network layer level automatically when a mobile host moves among networks of different communication technologies while continuing communication with a fixed host. SOLUTION: The mobile host MH comprises a communication interface state managing means 11 which monitors a state of communication of first and second communication interfaces IF1 and IF2 and performs processing according to the results or the monitoring, an address correspondence managing part 12 which manages care-of addresses assigned to the communication interfaces IF1 and IF2 by making them correspond to respective communication interfaces, packet queues 14 and 16 for transmission corresponding to respective communication interfaces IF1 and IF2, and packet queues 15 and 17 for receiving. A packet relay device PX has an HA/CoA correspondence table which associates a home address HA assigned to the mobile host MH with a care-of address CoA of the communication interface usable at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication interface automatic switching method and a communication interface automatic switching method in which a mobile communication means can move between networks using different communication technologies while continuing communication with a fixed communication means. For switching systems.

[0002]

2. Description of the Related Art Recently, with the advance of network communication technology, communication performed between information processing apparatuses has been diversified. In particular, the development of portable mobile communication devices has been remarkable, and it is expected that the range of use will be further expanded and the forms of use will be further diversified in the future.

For example, when such a mobile communication device communicates with a certain fixed-side communication device, a different communication technology (different in network address) is used due to the movement of the mobile communication device. There is an increasing demand for a communication system that can continue communication with the fixed-side communication device even when entering a network.

As an example, in one place, Bluetooth
A communication technology that enables communication with a fixed host using a network based on the IEEE802.11b standard (used for wireless LAN, etc.) in some cases. There are also requests.

[0005]

Conventionally, there are many techniques for improving communication between mobile communication means and fixed communication means. For example, JP-A-6-260990, JP-A-7-2
26973 both aims to reduce unnecessary switching between modes in a mobile communication system in which a plurality of mobile communication means select one of the mobile communication modes for communication. The present invention relates to a mobile communication device that integrates a plurality of mobile communication modes having different wireless interfaces such as a communication network and a satellite mobile communication network, and a mobile communication system, which is a wireless interface at a so-called data link layer level. Communication, as described above, such that the mobile communication means can continue communication with the fixed communication means while moving at the network layer level (different network addresses) using different communication technologies. It is different from the system.

[0006] On the other hand, there is a technique that can continue communication with the fixed communication means even when the mobile communication means enters a network using a different communication technique. For example, RFC2
MobileIPv4 (version specified in 002
There is a technique 4). In Mobile IP specified in this RFC2002, location transparency of mobile communication means,
Although movement transparency is realized, it is not possible to achieve position transparency and movement transparency of the mobile communication means while switching a plurality of communication interfaces.

In Japanese Patent Application Laid-Open No. 11-355281, Mobile
2. Description of the Related Art In a mobile communication system that connects to an IP network using an IP, the IP is efficiently routed within the system.
It realizes packet transfer, but this streamlines IP packet transfer when a mobile communication device moves using only one wireless interface, and moves while switching a plurality of wireless interfaces. The communication at the time is not described.

Accordingly, the present invention provides an automatic communication interface switching method having a function of automatically switching to a network layer level when switching a communication interface to be used in a communication device having a Mobile IP function and a plurality of communication interfaces. And an automatic communication interface switching system.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, a communication interface automatic switching method according to the present invention has a plurality of communication interfaces corresponding to a plurality of networks using different communication technologies, and a communication interface switching method.
The mobile communication means having an object IP function cooperates with a packet relay device, uses the Mobile IP function, and switches the plurality of communication interfaces, thereby continuing communication with the fixed communication means. A method for automatically switching between communication networks, the method comprising: monitoring a communication state of the plurality of communication interfaces, and using a communication interface corresponding to a certain network based on the monitoring result. Is detected, the temporary address assigned to the available communication interface is acquired and registered, and the temporary address is also notified to the packet relay device. The relay device registers the temporary address, and thereby, The communication unit and the fixed-side communication unit perform communication using the packet relay device using a fixed address assigned to the mobile-side communication unit and a temporary address assigned to the communication interface. .

When the mobile communication means detects that the other communication interface is becoming available during the movement from the certain network to another network, the detection result is obtained. Based on the above, while acquiring and registering a temporary address assigned to the other communication interface, the temporary address is notified to the packet relay device, and the packet relay device Register in addition to the already registered temporary address, whereby the mobile communicator and the fixed communicator communicate with the fixed address assigned to the mobile communicator and Using each temporary address assigned to the communication interface of Performs communication using the equipment.

[0011] When it is detected from this state that the other communication interface can be used, the communication interface is switched based on the detection result, and the communication interface corresponding to the pre-movement network is changed. The packet relay device notifies the temporary stop of the use of the address assigned to the communication interface to the packet relay device, and the packet relay device deletes the registration of the temporary address notified of the stop of the use, whereby the mobile side The communication unit and the fixed-side host use the fixed address assigned to the mobile-side communication unit and the temporary address assigned to the communication interface corresponding to the moved network, and Perform communication using.

In such a communication interface automatic switching method, when the mobile communication means moves from one network to another network, the other communication interface can be used during the movement. In this state, communication packets addressed to the fixed communication means from the mobile communication means are respectively connected to transmission packet queues provided for each of the plurality of communication interfaces, and the communication packets from the fixed communication means to the mobile communication means. The communication packet addressed to the communication means is transmitted to the mobile communication means in the packet relay device as a communication packet addressed to each of the temporary addresses assigned to the respective communication interfaces.

In the method for automatically switching communication interfaces, when the mobile communication means moves from the certain network to another network, the use of communication interfaces corresponding to the plurality of networks is required during the movement. In the enabled state, it is possible to set a selection criterion for selecting a communication interface, and it is also possible to select a communication interface to be used based on the set selection criterion.

Further, the communication interface automatic switching system according to the present invention has a plurality of communication interfaces corresponding to a plurality of networks using different communication technologies, and the mobile communication means having the Mobile IP function includes a packet relay device. In cooperation with the Mobil
e. a communication interface automatic switching system which is capable of moving between the plurality of networks while continuing communication with a fixed communication means by using an IP function and switching the plurality of communication interfaces. A communication interface state management unit that monitors a communication state of each communication interface for each of the plurality of communication interfaces, detects the communication state, and performs a process according to a result of the detection; An address correspondence management unit that manages a temporary address assigned to the communication interface acquired by the mobile communication means in association with each communication interface; and a transmission packet queue and reception provided in the plurality of communication interfaces. And a packet queue, wherein the packet relay device comprises: And a table for associating the temporary address assigned to the communication interface serial moving side communication means to the assigned fixed address and said moving side communication means is acquired.

The mobile communication means monitors the communication status of the plurality of communication interfaces, and when it is detected based on the monitoring result that the communication interface corresponding to a certain network can be used. Obtains and registers the temporary address assigned to the available communication interface, notifies the temporary address to the packet relay device, and registers the temporary address in the packet relay device. Thereby, the mobile communication means and the fixed communication means,
Communication using the packet relay device is performed using the fixed address assigned to the mobile communication means and the temporary address assigned to the communication interface.

When the mobile communication means detects that the other communication interface is becoming available during the movement from the certain network to another network, the detection result is obtained. Based on the above, while acquiring and registering a temporary address assigned to the other communication interface, the temporary address is notified to the packet relay device, and the packet relay device Register in addition to the already registered temporary address, whereby the mobile communicator and the fixed communicator communicate with the fixed address assigned to the mobile communicator and Using each temporary address assigned to the communication interface of Performs communication using the equipment.

Then, when it is detected from this state that the other communication interface can be used, the communication interface is switched based on the detection result, and the communication interface corresponding to the network before the movement is performed. The packet relay device notifies the temporary stop of the use of the address assigned to the communication interface to the packet relay device, and the packet relay device deletes the registration of the temporary address notified of the stop of the use, whereby the mobile side The communication unit and the fixed-side host use the fixed address assigned to the mobile-side communication unit and the temporary address assigned to the communication interface corresponding to the moved network, and Perform communication using.

In such a communication interface automatic switching system, when the mobile communication means moves from one network to another network, the other communication interface can be used during the movement. Then, the communication packets from the mobile communication means to the fixed communication means are respectively connected to respective transmission packet queues provided for the plurality of communication interfaces, and the fixed communication means transmits the communication packets to the fixed communication means. The communication packet addressed to the means is transmitted to the mobile communication means as a communication packet addressed to each of the temporary addresses assigned to the respective communication interfaces in the packet relay device.

Further, in such a communication interface automatic switching system, the mobile communication means includes a communication interface selection criterion management means, and when the mobile communication means moves from one network to another network, the communication interface selection reference management means is provided. In the state where the communication interfaces corresponding to the plurality of networks can be used during the movement, it is possible to set a selection criterion for selecting which communication interface to use, and use the communication interface based on the set selection criterion. It is also possible to select a communication interface.

As described above, according to the present invention, the communication state of the plurality of communication interfaces is monitored for each communication interface, so that the optimum communication interface at that time can be selected. And
Switching from the currently used communication interface to the next communication interface is performed in two steps. At this time, a temporary address (care of address) of each communication interface is acquired, and each acquired communication interface is acquired. The care of address is also notified to the packet relay device side, and in the packet relay device, the fixed address (home address) assigned to the mobile communication means and the care of address assigned to each communication interface The communication between the mobile communication means and the fixed communication means is performed so that the communication from the fixed communication means to the mobile communication means is performed during the switching of the communication interface. The packet is the communication interface before switching and the communication after switching. Sent to both addressed interface.

Thus, it is possible to reduce a communication packet loss from the fixed communication means to the mobile communication means when the communication interface is switched. Also, the communication packets transmitted from the mobile communication means to the fixed communication means during the communication interface switching period are arranged in transmission packet queues provided in the respective communication interfaces. The communication packet loss from the side communication means to the fixed side communication means can be reduced.

As described above, according to the present invention, it is possible to provide a communication system having a function of automatically switching not only the data link layer but also the network layer level when switching the communication interface.

Further, when the mobile communication means moves from the certain network to another network, in the state where the communication interfaces corresponding to the plurality of networks can be used during the movement, any communication interface is used. A criterion for selection can be set, and an optimum communication system can be selected based on the criterion.

Specifically, for example, the transfer rate of communication,
When multiple communication interfaces are available using the size and band of the radio wave reception level as a selection criterion, for example, a setting such as selecting the communication interface with the higher transfer rate or the one with the higher radio wave reception level There are various possible settings, such as setting of selecting a communication interface with a larger bandwidth and setting of selecting a communication interface with a wider band.

Further, if there is a difference in communication costs, it is possible to make settings such as selecting the one with the lower communication cost. In a state where a plurality of communication interfaces can be used, the user's preference and the current time can be selected. It is possible to select an optimum communication interface according to a situation.

[0026]

Embodiments of the present invention will be described below. The contents described in this embodiment are as follows.
The present invention includes both the communication interface automatic switching method and the communication interface automatic switching system of the present invention.

As described above, according to the present invention, different communication methods are performed by moving a mobile communication means (hereinafter, referred to as a mobile host) that is communicating with a fixed communication means (hereinafter, referred to as a fixed host). The present invention realizes a communication system that can continue communication with a fixed host even when entering a network using technology (different network addresses).

In order to realize this, the present invention provides a
In a mobile station having an ile IP function and a plurality of communication interfaces, the mobile station has a function of enabling not only switching of a data link layer but also changing of an IP address at a network layer level. Before describing the embodiments of the present invention, first, MobileI
P will be briefly described.

FIG. 1 schematically shows a configuration of a communication system for explaining the Mobile IP, in which a fixed host FH is provided with a mobile host MH, and the mobile host MH is connected to a Bluetooth network N1. A network N2 of the IEEE802.11b standard (used for wireless LAN, etc.) using a communication technology different from this Bluetooth
2 shows an example of performing communication with the fixed host FH while moving to the fixed host FH.

The address (home address HA) of the packet relay device PX having the function of Home Agent is assigned to the mobile host MH from the packet relay device PX. The temporary address (referred to as care of address CoA) in N1) is Foreig
n Assigned from AgentFA1.

It should be noted that the Foreign Agent FA1 is notified by the mobile host MH of what home address has been assigned to the mobile host MH, whereby the Foreign Agent FA1 instructs the packet relay apparatus PX to the mobile host MH. Notify if a proper care of address has been assigned. Thereby, the packet relay apparatus PX sends the home address (H
A) / Care of address (CoA) correspondence table (hereinafter referred to as HA / CoA correspondence table) is created.

The home address HA assigned to the mobile host MH is referred to as "HA-MH".
Network N1 assigned to this mobile host MH
"CoA-MH1" for care of address CoA
And

As described above, the mobile host MH has two addresses, the home address HA and the care-of-address CoA, and the home address HA is unchanged and the care-of-address C
The oA is assigned a different address each time depending on the network in which the oA is located.

Then, the fixed host FH becomes the mobile host MH.
The communication is performed using the home address assigned to the mobile host MH as the destination address. For example, if the address of the fixed host FH itself is "F
HA-FH ", the own address" FHA-FH "and the other party's address. In this case, first, the home address of the mobile host MH is" H-FH ".
A-MH "is written in the communication packet and transmitted.

As a result, the communication packet is received by the packet relay device PX, and the packet relay device PX having received the communication packet refers to the HA / CoA correspondence table to specify which mobile host is the destination. I do. According to this HA / CoA correspondence table, in this case, it is understood that “HA-MH” and “CoA-MH1” are associated with each other, and the final destination is the care-of-address “CoA-MH1”. You can see that.

Thus, the packet relay device PX
The address information written in the communication packet from the fixed host FH, that is, the address “F” of the fixed host FH itself
In the “HA-FA” and the destination address “HA-MH”, the destination address “HA-MH” is set to the mobile host MH.
Is rewritten to the care-of address “CoA-MH1” assigned at that time, and the care-of address “CoA-MH1” is transmitted as the destination address.
Thereby, the communication packet can reach the mobile host MH which is the final destination.

Then, from the mobile host MH to the fixed host F
In the case of communication to H, the home address “HA-MH” assigned to the mobile host MH is written as the address of the mobile host MH itself, and the address “FHA-FH” of the fixed host FH is written as the destination address. Write and send.

When the mobile host MH communicates with the fixed host FH as described above, the home address is used as the source address because the fixed host F
This is because when communication is performed from the H to the mobile host MH, the communication is performed via the packet relay device PX. That is, a communication packet in which “FHA-FH” is written as the destination address and “HA-MH” is written as the source address arrives at the fixed host FH, and a response to the communication packet is sent from the fixed host FH to the mobile host MH. In this case, if a communication packet in which “HA-MH” is written as the destination address and “FHA-FH” is written as the source address is sent, the above-described procedure is repeated.
ooth mobile host MH existing in network N1
Can communicate with the fixed host FH, and the communication procedure is the procedure of the thick arrows Y1, Y2, and Y3 shown in FIG.

Then, the mobile host MH moves to the IEE
If it enters the network N2 of the E802.11b standard, the care-of address “CoA-MH2” is assigned as a temporary address from the Foreign Agent FA2. Note that the home address “HA-MH” is invariable and therefore is kept.

In this state, when the fixed host FH communicates with the mobile host MH, as described above, the fixed host FH
It writes its own address “FHA-FH” and the home address “HA-MH” of the mobile host MH as the address of the other party in a communication packet and transmits it.

As a result, the communication packet is received by the packet relay device PX, and the packet relay device PX having received the communication packet refers to the HA / CoA correspondence table to specify which mobile host is addressed. . According to the HA / CoA correspondence table, in this case, the table has been updated and “HA-MH”
And “CoA-MH2” are associated with each other, and the final destination is the care-of-address “CoA-MH”.
It can be seen that the mobile host is “2”.

As a result, the packet relay device PX
In the address information written in the communication packet from the fixed host FH, that is, in the address “FHA-FH” of the fixed host FH itself and the address “HA-MH” of the destination, the destination address “HHA-MH” is set to the mobile host. The care of address “CoA- assigned to the MH”
MH2 ”and the care-of-address“ CoA-
MH2 "as the destination address.

As a result, the communication packet can reach the mobile host MH (which is located in the network N2 of the IEEE802.11b standard), which is the final destination.

In this state, when communication is performed from the mobile host MH to the fixed host FH, the mobile host M
In this case, the home address “HA-MH” assigned to itself is written as the address of H, and the address “FHA-F” of the fixed host FH is written as the destination address.
"H" is written and transmitted. By repeating this procedure, the network N of the IEEE802.11b standard is
2 can communicate with the fixed host FH.

It should be noted that the description with reference to FIG.
It is an explanation in IPv4 (version 4), but Mobil
Also in eIPv6 (version 6), it can be realized by a similar concept. In this MobileIPv6, Foreign
AgentFA is no longer needed. Note that this Mob
In the case of ileIPv6, the mobile host MH is, for example, an Internet Control Message Protocol (ICMPv6).
The care of address can be obtained automatically by using the function of rsion6).

The present invention utilizes such a Mobile IP function, and an embodiment of the present invention will be described below. Before describing the embodiment, the basic operation of the present invention will be described with reference to FIG. This FIG.
3 shows the configuration of H and its information content.

In FIG. 2, the mobile host MH has first and second communication interfaces IF1 and IF2,
The first communication interface IF1 corresponds to a network N1 using a certain communication technology, and the second communication interface IF2 corresponds to a network N2 using another communication technology.

The mobile host MH includes a communication interface status management unit 11, an address correspondence management unit 12,
ile IP function unit 13, first communication interface I
F1 transmission packet queue 14 and reception packet queue 15; second communication interface IF2 side transmission packet queue 16 and reception packet queue 17;
I / O driver 18 for communication interface IF1 of
I / O driver 1 for second communication interface IF2
9. It has a communication interface selection criterion management unit 20.

The communication interface status management unit 11
Are the first and second communication interfaces IF1, IF
2 is monitored, the monitoring result is managed as communication interface information, and processing is performed based on the monitoring result. The communication interface information to be managed is the first
The communication interface information D11 on the side of the communication interface IF1 includes the name of the communication interface, the quality of the communication state, availability, and the like. Similarly, the communication interface information D1 on the side of the second communication interface IF2
The second is the name of the communication interface, the quality of the communication state, and the availability.

The processing based on the monitoring result performed by the communication interface state management unit 11 monitors each of the communication interfaces IF1 and IF2 and generates a communication interface switching preparation event and a communication interface switching event based on the monitoring results. This is a process of generating a communication interface or selecting an available communication interface at that time. When an available communication interface is selected, it can be determined by referring to information held by the communication interface selection criterion management unit 20. This will be described later.

On the other hand, the address correspondence management section 12 associates a communication interface with a care-of-address CoA assigned to the communication interface and manages it as address correspondence information. The information is stored in the first communication interface IF1
The address correspondence information D21 on the side is a communication interface name and a care-of-address CoA acquired corresponding to the communication interface. Similarly, the address correspondence information D22 on the second communication interface IF2 side is communication The interface name and the care-of-address CoA acquired corresponding to the communication interface.

Further, the packet relay device PX has a Home Age
If the mobile host MH receives a care-of-address registration message or a use suspension message acquired by the mobile host MH, and receives a care-of-address registration message, the home address assigned to the mobile host MH And a care-of address assigned to the mobile host MH at that time (HA / CoA correspondence table), and when the use stop message is received, it is registered in the HA / CoA correspondence table. Delete the care of address.

The operation of such a configuration will be described. In the initial state, it is assumed that the mobile host MH is communicating with the fixed host FH using the first communication interface IF1, and the assigned home address HA is “HA-MH” and the first communication interface I
The care-of address assigned to F1 is referred to as “CoA-M
H1 ”. FIG. 2 shows the information contents of the mobile host MH and the packet relay device PX in this initial state. Further, thick arrows Y1, Y2, and Y2 in FIG.
Y3 indicates a communication path between the communication host MH and the fixed host FH as described with reference to FIG. “O” and “X” between the networks N1 and N2 and the first and second communication interfaces IF1 and IF2 indicate a communication state, and “O” indicates a communication state of “good”. "And" x "indicate that communication is not possible.

As described above, while the mobile host MH is communicating with the fixed host FH using the first communication interface IF1, the communication interface state monitoring unit 11 communicates with the first communication interface IF1 and the second communication interface IF1. The status of the interface IF2 is monitored. Then, it is assumed that the movement of the mobile host MH allows the use of the second communication interface IF2 at some point.

In such a state, the mobile host MH
Acquires the care-of-address “CoA-MH2” assigned to the second communication interface IF2 by some address acquisition means. Note that the acquisition of the care of address “CoA-MH2” is performed in the example of FIG.
oreign AgentFB, but Mobile
In the case of IPv6, as described above, for example, it can be obtained by using an address obtaining unit such as ICMPv6.

The care-of-address “CoA-MH2” thus obtained is registered by the address correspondence management unit 12 as address correspondence information corresponding to the second communication interface IF2.

Then, the mobile host MH moves further,
When the communication interface state management unit 11 detects the deterioration of the communication state of the first communication interface IF1, a communication interface switching preparation event is generated, and the mobile host MH sets the care-of address “CoA-MH2” of the second communication interface IF2. Is transmitted to the packet relay apparatus PX to register the care-of-address "CoA-MH2".

In such a state, the mobile host M
H transmits a communication packet to the fixed host FH to the first communication interface IF1 and the second communication interface IF
2 are connected to both the transmission packet queues 14 and 16 respectively.

On the other hand, the communication interface status monitor 11
Detects a state where the first communication interface IF1 cannot be used or is in a state where it is difficult to use the first communication interface IF1, and generates a communication interface switching event.
Accordingly, the mobile host MH transmits a use stop message of the care of address “CoA-MH1” to the packet relay device PX, stops using the first communication interface IF1, and gives the address correspondence management unit 12 a care of care. Instruct the deletion of the address of “CoA-MH1”. In this state, the mobile host MH uses the second communication interface IF2 to transmit the packet
The communication with the fixed host FH is continued by the relay of X.

Incidentally, the packet relay apparatus PX is configured to associate the home address “HA-MH” of the mobile host MH with the care-of address at that time.
/ CoA correspondence table exists. That is, when the first communication interface IF1 is used, this H
The A / CoA correspondence table includes the home address “HA-MH” of the mobile host MH and the first communication interface IF.
1 assigned to the care-of address “CoA-MH”
However, when the communication interface switching process is started by a communication interface switching preparation event from the communication interface state monitoring unit 11, the packet relay device PX sets the mobile host M
H sent the care-of-address "CoA-MH"
2), and additionally registers CoA-MH2 as the care-of address corresponding to the home address "HA-MH" of the mobile host MH together with the care-of-address "CoA-MH1" already registered. .

Therefore, at that time, HA / CoA
In the correspondence table, the home address “HA-MH” of the mobile host MH and the care-of address “CoA-
"MH1" and "CoA-MH2" are associated with each other.

In this state, the packet relay device P
X receives the communication packet addressed to the home address “HA-MH” sent from the fixed host FH, and sets the destination of the communication packet to the care-of-address “CoA-MH”.
1 "and the care-of address" CoA-MH2 "to both the first and second communication interfaces IF1 and IF2.

Then, the communication interface status monitoring unit 1
When the communication interface switching process is completed by the communication interface switching event from No. 1,
The packet relay device PX receives the use stop message of the care of address “CoA-MH1” from the mobile host MH, and deletes the care of address “CoA-MH1” from the HA / CoA correspondence table of the mobile host MH.

By performing the processing according to the above-described procedure, the mobile host MH can move from the network N1 using a certain communication technology to the other network N2 using a different communication technology. FH
The communication with can be continued.

Next, a specific embodiment will be described. In this embodiment, as shown in FIG. 1, two communication areas using different communication technologies are considered: a network N1 based on Bluetooth and a network N2 based on the IEEE 802.11b standard using a communication technology different from Bluetooth. . Therefore, the mobile host MH has the Bluetooth
Communication interface I corresponding to the communication technology according to
F1 and a second communication interface IF2 corresponding to the communication technology of the IEEE802.11b standard.

First, the communication system according to this embodiment is assumed as follows. The mobile host MH includes first and second communication interfaces IF1 and IF2, and replaces the first communication interface IF1 with a communication interface (hereinafter, referred to as a communication interface corresponding to a network N1 using Bluetooth).
Bluetooth interface IF1), and the second communication interface IF2 is a communication interface of the IEEE802.11b standard (hereinafter, IEEE802.11b interface IF).
2).

The mobile host MH is a fixed host FH (I
P address is “FHA-FA”), and the Bluetooth interface I is in the initial state.
It is assumed that communication using F1 is being performed, the communication gradually moves from that state, and finally switches to communication using the IEEE802.11b interface IF2.

The home address of the mobile host MH is “HA-MH”, the care-of address assigned to the Bluetooth interface IF1 is “CoA-MH1”,
It is assumed that the care of address assigned to the IEEE802.11b interface IF2 is “CoA-MH2”. The Mobile IP used here is Mobile
IPv6.

In such a system, a state where the mobile host MH is connected to the network N1 using the Bluetooth interface IF1 and is communicating with the fixed host FH is defined as an initial state. The operation from this initial state until the mobile host MH gradually moves while continuing communication with the fixed host FH and eventually enters a state in which communication using the IEEE802.11b interface IF2 is performed will be described.

FIGS. 3 to 6 are diagrams for explaining the embodiment of the present invention, and are diagrams for explaining changes in information contents of the mobile host and the packet relay device PX in the process of moving the mobile host MH.

FIG. 3 is a diagram for explaining a state (initial state) in which the mobile host MH is in the network N1 based on Bluetooth. FIGS.
h illustrates a state in which the network N1 is transitioning to the network N2 according to the IEEE 802.11b standard,
FIG. 4 is a diagram illustrating a state during movement, and FIG. 5 is a diagram illustrating a state where a communication interface switching preparation event is generated from the communication interface state management unit 11 during movement.

FIG. 6 shows that the mobile host MH has a Bluetooth connection.
FIG. 4 is a diagram illustrating a state in which a communication interface switching event has occurred from the communication interface state management unit 11 in a state where the network interface has escaped from the network N1 and has entered the network N2 according to the IEEE802.11b standard.

First, in the initial state in FIG.
As described above, the mobile host MH communicates with the fixed host FH using the Bluetooth interface IF1. At this time, the assigned home address HA is “HA-MH”, and the home address “H” is assigned.
"A-MH" is unchanged. The care-of-address CoA assigned to the Bluetooth interface IF1 is “CoA-MH1”.

Therefore, in this initial state, the address correspondence information (information indicating the correspondence between the communication interface name and the care of address CoA) managed by the address correspondence management unit 12 of the mobile host MH is the address on the Bluetooth interface IF1 side. As shown in FIG. 3, the correspondence information D21 is “CoA: CoA-MH1” for “interface: Bluetooth”.

On the other hand, the IEEE802.11b interface side IF
2, the address correspondence information D22 of FIG.
“CoA” for “Interface: IEEE802.11b”
:-". This indicates that the care of address on the side of the IEEE802.11b interface IF2 has not been allocated.

The communication interface information (communication interface name, information indicating the quality of the communication state, and information indicating the availability) managed by the communication interface state management unit 11 of the mobile host MH includes the communication interface of the Bluetooth interface IF1. As shown in FIG. 3, the information D11 is “interface: Bluetooth”, “communication status: good”, and “usability: available”.

On the other hand, the IEEE802.11b interface IF
As shown in FIG. 3, the communication interface information D12 on the second side includes “interface: IEEE802.11b”, “communication state:
− ”And“ usability: unavailable ”.

In the state shown in FIG. 3, the Bluetooth interface IF1 side has a good communication state and can use the Bluetooth interface IF1.
The EEE802.11b interface IF2 side indicates that the communication state is not possible and the IEEE802.11b interface IF2 cannot be used.

On the other hand, at this time, the HA / CoA correspondence table in the packet relay device PX indicates that the mobile host MH
Home address “HA-MH” and its care-of address “CoA-MH1”. As a result, as described above, the mobile host MH has the Bluetooth
Using the interface IF1, communication with the fixed host FH can be performed by relaying the packet relay device PX.

The thick arrow Y in FIGS.
Reference numerals 1, Y2, and Y3 indicate communication paths between the mobile host MH and the fixed host FH, as described above. Also Blu
“○”, “△”, and “×” shown between the network N1 and the Bluetooth interface IF1 by etooth and between the network N2 and the IEEE802.11b interface IF2 according to the IEEE802.11b standard indicate the communication state. “○” indicates that the communication state is “good”, “、” indicates that the communication state is “bad”, and “×” indicates that communication is not possible.

The procedure of the communication performed by the Mobile IP function unit 13 has already been described in detail and will not be described here.

Next, the mobile host MH starts moving from such an initial state, and the network N
1 and the network N2 according to the IEEE802.11b standard reach an almost intermediate position of the overlapping portion, the mobile host M
The information held by H is as shown in FIG.

In the state shown in FIG.
As shown in FIG. 4, the address correspondence information managed by the address correspondence management unit 12 of H is “interface:
“CoA: CoA-MH1” for “Bluetooth”. On the other hand, as shown in FIG. 4, the address correspondence information D22 on the side of the IEEE802.11b interface IF2 is "CoA: Co" for "interface: IEEE802.11b".
A-MH2 ".

That is, when the mobile host MH is an IEEE 802.11b
When the communication interface monitoring unit 11 enters the network N2 based on the standard, the communication interface monitoring unit 11
Of the radio reception level of the mobile host MH, and the IEEE802.11b interface IF2 becomes available.
Acquires the care of address "CoA-MH2"
If the address management unit 12 is an IEEE802.11b interface IF
Update the address correspondence information on the two sides, and as described above,
For “Interface: IEEE802.11b”, “Co
A: CoA-MH2 ".

The communication interface information managed by the communication interface state management unit 11 of the mobile host MH includes, as shown in FIG. 4, the communication interface information D11 on the side of the Bluetooth interface IF1, “Interface: Bluetooth” and “Communication state: bad "," Availability: a
vailable ". On the other hand, as shown in FIG. 4, the communication interface information D12 on the side of the IEEE802.11b interface IF2 includes "interface: IEEE802.11b",
"Communication status: bad" and "usability: unavailable".

This is the Bluetooth interface IF1
Although the communication state is poor on the side, the Bluetooth interface IF1 can still be used, and the IEEE802.11b interface IF2 side has a bad communication state, indicating that the IEEE802.11b interface IF2 cannot be used yet. That is, the communication interface has not been switched yet.

On the other hand, at this time, the HA / CoA correspondence table in the packet relay device PX indicates that the mobile host MH
Of the home address “HA-MH” and its care-of address “CoA-AMH” are held as they are. Thus, even in the state of FIG. 4, as described above, the mobile host MH can communicate with the fixed host FH by using the Bluetooth interface IF1 and relaying the packet relay device PX.

Then, from the state shown in FIG.
When H moves further and reaches a position where the network N1 based on Bluetooth and the network N2 based on the IEEE802.11b standard overlap, and reaches a position where the network N2 based on the IEEE802.11b standard enters more, the information of the mobile host MH is held. Is as shown in FIG.

In the state of FIG. 5, the mobile host M
As shown in FIG. 5, the address correspondence information managed by the address correspondence management unit 12 of H is “interface:
“CoA: CoA-MH1” is held as it is for “Bluetooth”, and the address correspondence information D22 on the side of the IEEE802.11b interface IF2 is “CoA: CoA” for “interface: IEEE802.11b” as shown in FIG.
−MH2 ”.

This state is a state in which the communication interface state management unit 11 detects a decrease in the level of the received radio wave of the radio wave of the Bluetooth interface IF1, and the communication interface state management unit 11 generates a communication interface switching preparation event. By the mobile host M
H sends the care-of-address “Co” to the packet relay device HA.
A-MH2 "registration request message is transmitted.

Then, after a while (IEEE802.1
1b) (until the switching to the interface IF2 is completed), the communication packet sent from the mobile host MH to the fixed host FH stores the transmission packet P1 in the transmission packet queues 14 and 16 for both communication interfaces. Connecting.

When these communication packets P1 are sent to the fixed host FH and the same transmission packet P1 is received by the fixed host FH, only one of the transmission packets is adopted to prevent duplication.

The communication interface information managed by the communication interface state management unit 11 of the mobile host MH is as follows. As shown in FIG. 5, the communication interface information D11 on the side of the Bluetooth interface IF1 includes “interface: Bluetooth” and “communication state: bad ", but since the communication interface has not been switched,
"Availability: available". On the other hand, IEEE80
2.11b The communication interface information D12 on the interface IF2 side is, as shown in FIG.
802.11b "and" communication state: good ", but the communication interface has not been switched to the IEEE802.11b interface IF2, so" availability: unavailable ".
It has become.

On the other hand, when receiving the registration request message of the care-of address “CoA-MH2” from the mobile host MH, the packet relay device PX adds it to the HA / CoA correspondence table.

As a result, at this point, the HA / CoA correspondence table of the packet relay device PX stores “CoA-MH1” and “C” for the home address “HA-MH”.
oA-MH2 ”are associated with each other.

Then, after a while (IEEE802.1
1b) Until the switching to the interface IF2 is completed, the packet relay device PX transmits the communication packet P2 from the fixed host FH to the mobile host MH as a communication packet addressed to the care-of address “CoA-MH1” and a care-of Relay processing is performed as a communication packet addressed to the address “CoA-MH2”.

As described above, the communication packet from the fixed host FH to the mobile host MH (to the home address “HA-MH”) is transferred to the two care-of addresses “CoA-MH”.
1 and "CoA-MH2" are relayed as communication packets P2, as shown in FIG. 5, when both the Bluetooth interface IF1 and the IEEE802.11b interface IF2 are being used. This is because packet loss is likely to occur, so that even if one communication interface becomes unavailable, reception can be performed using the other communication interface.

Then, from the state shown in FIG.
When H moves further and escapes from the network N1 based on Bluetooth and reaches a position where only the network N2 based on the IEEE802.11b standard is entered, the information held by the mobile host MH is in a state as shown in FIG.

In the state of FIG. 6, the mobile host M
As shown in FIG. 6, the address correspondence information managed by the address correspondence management unit 12 of H is “interface:
"CoA:-" for "Bluetooth" and IEEE80
2.11b Address correspondence information D2 on interface IF2 side
As shown in FIG. 6, “Interface: IEEE802.1
1b "," CoA: CoA-MH2 ".

The state is such that the communication interface state management unit 11 changes the state of the received radio wave level of the radio wave of the Bluetooth interface IF1 from the state of the Bluetooth interface IF1.
1, the communication interface state management unit 11 generates a communication interface switching event, and accordingly, the mobile host MH
Sends a care-of-address “CoA” to the packet relay device PX.
-MH1 "is sent, and
The use of the Bluetooth interface IF1 is stopped.

As a result, the communication interface information managed by the communication interface state management unit 11 of the mobile host MH includes the communication interface information D11 on the Bluetooth interface IF1 side as shown in FIG. :-"
Communication is disabled, and the status is “usable / unavailable”. On the other hand, the IEEE802.11b interface IF2
As shown in FIG. 6, the communication interface information D12 on the side includes “interface: IEEE802.11b”, “communication state:
"good" and the communication interface has been switched to the IEEE802.11b interface IF2 side, so that "availability: available".

On the other hand, the packet relay device PX receives the use stop message of the care of address “CoA-MH1” from the mobile host MH, deletes the care of address “CoA-MH1” from the HA / CoA correspondence table, The HA / CoA correspondence table indicates that the home address “HAd-MH” of the mobile host MH is “CoA-MH”.
Only the care-of address of "2" is associated.

Therefore, in this state, the packet relay apparatus PX sends the care-of-address “CoA-MH2” to the communication packet from the fixed host FH to the mobile host MH (to the home address “HAd-MH”). Relay as a packet.

By the way, the mobile host MH moves from one network to another network (in the above-described embodiment, Blue
When moving from the network N1 by the tooth to the network N2 according to the IEEE802.11b standard, both of the communication interfaces (the Bluetooth interface IF1 or the IEEE802.11b interface IF2 in the above-described embodiment) are supported during the movement. When the communication interface is available, a criterion for selecting a communication interface can be set, and the selection criterion can be stored in the communication interface selection criterion management unit 20. Then, a communication system is selected based on the selection criterion stored in the communication interface selection criterion management unit 20.

Specifically, for example, the transfer speed of communication,
When multiple communication interfaces are available using the size and band of the radio wave reception level as a selection criterion, for example, a setting such as selecting the communication interface with the higher transfer rate or the one with the higher radio wave reception level There are various possible settings, such as setting of selecting a communication interface with a larger bandwidth and setting of selecting a communication interface with a wider band.

Furthermore, if there is a difference in communication costs, it is possible to make settings such as selecting the one with the lower communication cost, so that the optimum communication interface can be selected according to the user's preference and the situation at that time. Such a selection criterion can be defined in the communication interface selection criterion management unit 20.

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the gist of the present invention. For example, in the above embodiment, the mobile host MH has two communication interfaces (the Bluetooth interface IF1 and the IEEE8
02.11b interface IF2)
This is not limited to two, and three or more communication interfaces may be provided. According to this, for example, movement between networks using three or more different communication technologies becomes possible.

In the above-described embodiment, the communication interface state management unit 11 and the address correspondence management unit 12 are provided separately. However, these may be combined into one.

Also, in the above-described embodiment, Mobil
The eIP will be described using an example using MobileIPv6, and the system configuration in FIG. 1 shows an example using MobileIPv4, but the present invention is based on MobileIPv6.
6 and MobileIPv4.

Further, in the above-described embodiment, switching of the communication interface between wireless communication interfaces has been described as an example of the communication interface. However, the present invention is not limited to this, and the communication interface between the wireless communication interface and the wired communication interface is not limited thereto. Can be switched, and the present invention can be applied to switching of a communication interface between wired communication interfaces.

Further, according to the present invention, a processing program in which a processing procedure for realizing the present invention described above is described is created, and the processing program is recorded on a recording medium such as a floppy disk, an optical disk, or a hard disk. The present invention also includes a recording medium on which the processing program is recorded. Further, the processing program may be obtained from a network.

[0112]

As described above, according to the present invention, by monitoring the communication state of a plurality of communication interfaces for each communication interface, an optimum communication interface at that time can be selected. . Then, switching from the currently used communication interface to the next communication interface is performed in two steps. At this time, temporary addresses (care of addresses) of the respective communication interfaces are acquired, and the acquired respective addresses are acquired. The packet relay device is also notified of the care of address of the communication interface, and the packet relay device determines the fixed address (home address) assigned to the mobile communication means and the care address assigned to each communication interface. Since the communication between the mobile communication means and the fixed communication means is relayed by associating the fixed communication means with the address of the mobile communication means during the switching of the communication interface. Communication packets are switched with the communication interface before switching Sent both addressed to the communication interface.

As a result, the communication packet loss from the fixed communication means to the mobile communication means at the time of switching the communication interface can be reduced. Also, the communication packets transmitted from the mobile communication means to the fixed communication means during the communication interface switching period are arranged in transmission packet queues provided in the respective communication interfaces. The communication packet loss from the side communication means to the fixed side communication means can be reduced.

As described above, according to the present invention, it is possible to provide a communication system having a function of automatically switching not only the data link layer but also the network layer level when switching the communication interface.

Further, when the mobile communication means moves from the certain network to another network, it is possible to use a communication interface corresponding to the plurality of networks during the movement. A criterion for selection can be set, and an optimum communication system can be selected based on the criterion.

Specifically, for example, the transfer rate of communication,
When multiple communication interfaces are available using the size and band of the radio wave reception level as a selection criterion, for example, a setting such as selecting the communication interface with the higher transfer rate or the one with the higher radio wave reception level There are various possible settings, such as setting of selecting a communication interface with a larger bandwidth and setting of selecting a communication interface with a wider band. In addition, if there is a difference in communication costs, it is possible to make settings such as selecting the one with the lower communication cost.If multiple communication interfaces are available, it can be set according to user preferences and circumstances at that time. The most suitable communication interface can be selected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a communication system illustrating functions of Mobile IP used by the present invention.

FIG. 2 is a diagram for explaining a basic operation of the present invention, and shows the configuration of the mobile host MH and information contents of the mobile host MH and the packet relay device PX.

FIG. 3 is a diagram illustrating an embodiment of the present invention, illustrating a state in which a mobile host MH is in a network N1 based on Bluetooth.

FIG. 4 is a diagram illustrating a state in which a mobile host MH is transitioning from a network N1 based on Bluetooth to a network N2 based on the IEEE 802.11b standard.

FIG. 5 is a diagram illustrating a state in which the mobile host MH is transitioning from the network N1 based on Bluetooth to the network N2 based on the IEEE 802.11b standard, and is a diagram illustrating a state in which a communication interface switching preparation event occurs.

FIG. 6 shows that the mobile host MH escapes from the network N1 based on Bluetooth and the network N based on IEEE802.11b.
2 is a diagram illustrating a state in which the communication interface 2 has been entered, and a diagram illustrating a state in which a communication interface switching event occurs. FIG.

[Explanation of symbols]

Reference Signs List 11 communication interface state management unit 12 address correspondence management unit 13 Mobile IP function unit 14 transmission packet queue (first communication interface IF1 side) 15 reception packet queue (first communication interface IF1 side) 16 transmission packet queue ( (Second communication interface IF2 side) 17 Received packet queue (second communication interface IF2 side) 18 I / O driver (First communication interface IF)
1) 19 I / O driver (second communication interface IF)
20) Communication interface selection standard manager N1 Bluetooth network N2 IEEE802.11b standard network IF1 First communication interface (Bluetooth interface) IF2 Second communication interface (IEEE802.11b interface) PX packet relay device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04Q 7/34 H04Q 7/04 CF term (Reference) 5K030 HA08 HC09 HD06 JA11 JL01 JT09 KA13 LB05 5K033 CB08 CC01 DA05 DA19 DB18 5K034 EE11 HH01 HH02 HH06 HH63 JJ24 5K067 BB21 CC08 EE04 EE10 EE16 FF16 GG01 GG11 HH32 JJ11 JJ31 JJ66 JJ71

Claims (6)

[Claims] 1. A mobile communication device having a plurality of communication interfaces corresponding to a plurality of networks using different communication technologies, and having a Mobile IP function, cooperating with a packet relay device to provide the mobile device with the communication device.
A communication interface automatic switching method for using an IP function, and switching between the plurality of communication interfaces, so as to be able to move between the plurality of networks while continuing communication with a fixed-side communication unit, The communication state of the plurality of communication interfaces is monitored, and based on the monitoring result, when it is detected that the communication interface corresponding to a certain network can be used, the communication interface is allocated to the available communication interface. The temporary address is obtained and registered, and the temporary address is also notified to the packet relay device. The packet relay device registers the temporary address, thereby And the fixed communication means are fixed addresses assigned to the mobile communication means. And using a temporary address assigned to the communication interface, perform communication using the packet relay device, when the mobile communication means moves from the certain network to another network, during the movement, Upon detecting that the other communication interface is becoming available for use, based on the detection result, obtain and register the temporary address assigned to the other communication interface, and register the temporary address. And the temporary address is registered in addition to the already registered temporary address.
The mobile side communication means and the fixed side communication means use the fixed address assigned to the mobile side communication means and the respective temporary addresses assigned to the respective communication interfaces to perform the packet relaying. Communication using the device is performed, and when it is detected from this state that the other communication interface can be used, the communication interface is switched based on the detection result,
Notify the packet relay device of the temporary stop of the use of the address allocated to the communication interface corresponding to the network before the movement, and delete the registration of the temporary address notified of the stop of the use in the packet relay device. Thereby, the mobile-side communication means and the fixed-side host exchange the fixed address assigned to the mobile-side communication means and the temporary address assigned to the communication interface corresponding to the moved network. A communication interface using the packet relay device. 2. When the mobile communication means moves from the certain network to another network, the mobile communication means is in a state where the other communication interface can be used during the movement. Communication packets addressed to the fixed-side communication means are respectively connected to respective transmission packet queues provided for the plurality of communication interfaces, and communication packets addressed from the fixed-side communication means to the mobile-side communication means are 2. The communication interface automatic switching method according to claim 1, wherein the packet relay device transmits the communication packet to the mobile communication unit as a communication packet addressed to each of the temporary addresses assigned to the communication interface. 3. When the mobile communication means moves from one network to another network, in the state where communication interfaces corresponding to the plurality of networks can be used during the movement, any communication interface is used. It is possible to set the selection criteria for selection,
3. The communication interface automatic switching method according to claim 1, wherein a communication interface to be used is selected based on the set selection criterion. 4. A mobile side communication means having a plurality of communication interfaces corresponding to a plurality of networks using different communication technologies and having a Mobile IP function, cooperating with a packet relay apparatus to execute the mobile communication.
A communication interface automatic switching system that uses an IP function and switches between the plurality of communication interfaces, so that communication between the plurality of networks can be performed while continuing communication with a fixed communication unit, A communication interface state management unit that monitors a communication state of each communication interface for each of the plurality of communication interfaces, detects the communication state, and performs a process according to a result of the detection; An address correspondence management unit for managing a temporary address assigned to the communication interface acquired by the communication means in association with each communication interface; and a transmission packet queue and a reception queue provided for the plurality of communication interfaces. A packet queue, wherein the packet relay device is The mobile communication device includes a table that associates a fixed address assigned to the mobile communication device with a temporary address allocated to the communication interface acquired by the mobile communication device, wherein the mobile communication device includes a plurality of communication interfaces. Monitors the communication status of the network, and when it is detected based on the monitoring result that the communication interface corresponding to a certain network can be used, the temporary address assigned to the available communication interface. And the temporary address is also notified to the packet relay device, and the temporary address is registered in the packet relay device. The means comprises a fixed address assigned to the mobile communication means and a communication interface thereof. Using the temporary address assigned to the network, the communication using the packet relay device is performed, and when the mobile communication means moves from the certain network to another network, during the movement, the other Upon detecting that the communication interface is becoming available for use, based on the detection result, obtain and register the temporary address assigned to the other communication interface, and register the temporary address. Notify the packet relay device, the packet relay device registers its temporary address in addition to the already registered temporary address, whereby
The mobile side communication means and the fixed side communication means use the fixed address assigned to the mobile side communication means and the respective temporary addresses assigned to the respective communication interfaces to perform the packet relaying. Communication using the device is performed, and when it is detected from this state that the other communication interface can be used, the communication interface is switched based on the detection result,
Notify the packet relay device of the temporary stop of the use of the address assigned to the communication interface corresponding to the network before the movement, and delete the registration of the temporary address notified of the stop of the use in the packet relay device. Thereby, the mobile-side communication means and the fixed-side host exchange the fixed address assigned to the mobile-side communication means and the temporary address assigned to the communication interface corresponding to the moved network. A communication interface automatic switching system, wherein communication using the packet relay device is performed using the communication interface. 5. When the mobile communication means moves from the certain network to another network, the mobile communication means is in a state where the other communication interface can be used during the movement. Communication packets addressed to the fixed-side communication means are connected to respective transmission packet queues provided for each of the plurality of communication interfaces, and communication packets addressed to the mobile-side communication means from the fixed-side communication means are The communication interface automatic switching system according to claim 4, wherein the packet relay device transmits the communication packet to the mobile communication means as a communication packet addressed to each of the temporary addresses assigned to the communication interface. 6. The mobile communication means includes a communication interface selection criterion management means, and when the mobile communication means moves from one network to another network, the mobile communication means is connected to the plurality of networks during the movement. In a state where the corresponding communication interface can be used, it is possible to set a selection criterion of which communication interface is to be selected, and based on the set selection criterion,
6. A communication interface automatic switching system according to claim 4, wherein a communication interface to be used is selected.