JP3669366B2 - Mobile terminal and network interface switching method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile terminal and a network interface switching method for switching a network interface while continuing communication with a communication partner in connection between different networks or different types of wireless networks.
[0002]
[Prior art]
In recent years, with the advancement of IP network communication technology and mobile communication technology, the mobility and location transparency of mobile terminals are secured, and communication continues even if the mobile terminals move between different subnets or different Internet service providers There is an increasing demand for communication systems to be used. As a means for realizing this, for example, there is “Mobile IP” technology defined in RFC2002 and RFC3220 of IETF (see Non-Patent Document 1), and communication with a communication partner is continued even if a terminal moves across different subnets. It is known to be possible. In this mobile IP technology, a “mobile terminal” that is a communication terminal that moves through a network, a “home address” that is a universal IP address regardless of which network the mobile terminal is connected to, and a mobile terminal that is a destination network “Care of Address” temporarily used, “Home Agent” acting as a mobile terminal data receiver on the home network, “Foren Agent” acting as a mobile terminal data receiver on the destination network, etc. The
[0003]
As a method of switching the network interface by applying this “mobile IP”, the care-of address is acquired before switching the communication interface, and the care-of address is notified to the packet relay device that relays the packet. When switching the network interface, there is a method of notifying the packet relay device of the stop of use of the address before the movement again (for example, see Patent Document 1). Also, a method of switching the destination address of information to another interface while maintaining the state of the communication interface when moving within the areas by overlapping service areas provided by a plurality of types of mobile communication networks (for example, Patent Documents) 2).
[0004]
[Non-Patent Document 1]
Edited by IETF (Internet Engineering Task Force) "RFC (Request for Comments) 2002 and 3220"
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-290445
[0006]
[Patent Document 2]
JP 2003-125433 A
[0007]
[Problems to be solved by the invention]
In the communication interface switching method disclosed in Patent Document 1, registration request packet transfer from the mobile terminal to the packet relay apparatus is transmitted twice for switching. If the packet relay device that receives the packet is a home agent specified in Non-Patent Document 1, the packet to be transferred is copied to the care-of address included in the registration request packet, and is addressed to two care-of addresses before and after switching. Transfer data to When the mobile terminal confirms the movement process, a registration request packet, which is a request to stop using the old care-of address, is transmitted again from the mobile terminal to the packet relay device, and one care-of address from two care-of addresses. Change to In this way, two registration request packets are transmitted for switching the mobile terminal.
[0008]
In this way, the packet relay apparatus side is advantageous in taking measures to prevent data loss on the mobile terminal side because data is duplicated and transferred to two destinations during switching work. Since the registration request packet is transmitted, processing on the mobile terminal side may be complicated. Furthermore, when the number of mobile terminals in the system increases, for example, to n, the packet transfer device corresponds to 2 × n packet transfer destinations. Problems such as high traffic will remain.
[0009]
Moreover, in patent document 2, the process which switches to the address of a 2nd communication network interface is performed, overlapping the 1st type and the 2nd type communication service area, maintaining the reception state of a 1st network interface, Prevent data loss of mobile terminals. However, when the service area overlap area of the first network and the second network is intricately involved (see FIG. 19), for example, moving conditions such as moving from the first type to the second type and returning to the first type again. When this occurs, the IP address is reacquired in the first type communication interface. Therefore, problems such as insufficient IP addresses occur in a system in which such a movement condition is frequently generated and the number of terminals is large.
[0010]
The present invention has been made to solve the above-described problems. A mobile terminal and a network interface switching method capable of performing high-speed switching by setting a network interface and a tunnel device to be switched in advance are provided. The purpose is to provide.
[0011]
[Means for solving the problems]
In view of the above problems, the first feature of the present invention is that (a) setting means for setting information relating to an IP tunnel, which is a predefined communication procedure, for at least one or more network interfaces; (I) storage means for storing setting information for each IP tunnel setting; (c) movement detection means for receiving agent / router advertisement via network interface and detecting movement of own terminal; and (d) movement detection. A reuse determining means for determining whether the setting information of the network interface to be switched has been previously set and can be reused by referring to the setting information in the storage means; Reuse means for reusing network interface setting information when it is determined to be possible, and (f) network interface setting information. When reusing, by operating the routing table indicating the path of least communication data, and summarized in that a mobile terminal and an interface switching means for switching the network interface.
[0012]
Further, the first feature of the present invention is that: (g) a communication NIC list storage unit that stores a history of switching of network interfaces; And (i) the interface switching means refers to the history of the communication NIC list storage means when the communication state of the switching destination network interface deteriorates immediately after switching, and the network interface used immediately before And (n) network interface determining means for determining whether the same type of network interface is already connected to the access point that is the mobile connection destination, and (le) a memory in which information on the same type of network interface is already stored Card connected A mobile connection destination determination means for determining a candidate for an access point to be the next mobile connection destination, and (v) the interface switching means determines the next access point candidate by the mobile connection destination determination means. If it is, the network interface may be switched to correspond to the candidate access point.
[0013]
The second feature of the present invention is that (b) setting information relating to an IP tunnel, which is a predefined communication procedure, for at least one or more network interfaces; Storing the setting information in the storage means, (c) receiving the agent / router advertisement via the network interface, detecting the movement of the own terminal, and (d) attempting to switch after detecting the movement. Determining whether the network interface setting information has been previously set and is reusable by referring to the setting information in the storage means; and (e) when it is determined that the network interface is reusable. Reusing network interface configuration information, and (f) reusing network interface configuration information A step of switching a network interface by operating at least a route table indicating a route of communication data; and (g) a step of updating setting information used in communication when switching a network interface and storing the setting information in a storage unit. And a network interface switching method comprising:
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
(Communication system using mobile terminals)
First, an outline of the system operation of the mobile IP protocol using the mobile terminal according to the first embodiment of the present invention will be described with reference to FIGS. Hereinafter, when the mobile terminal 1 possessed by the user is performing data communication with the file server 2 that distributes information, the mobile terminal 1 is a router that is a foreign agent from the network of the packet relay device 3 that is a home agent. The operation of the mobile IP address when moving to the network of the device 4 will be described. Note that the packet relay device 3 and the router device 4 are capable of data communication with the file server 2 via a network 6 such as a LAN or a WAN.
[0015]
FIG. 1 shows a state before the mobile terminal 1 moves, and the mobile terminal 1 performs data communication with the file server 2 connected to the network 6 via the packet relay device 3. It is assumed that the router apparatus 4 has moved from this state to the network.
[0016]
The packet relay device 3 that registers a care-of address via the router device 4 broadcasts a network address at a constant cycle.
[0017]
After moving, the mobile terminal 1 receives the agent advertisement including the care-of address, which is periodically transferred from the router device 4, and detects that it has moved to the network of the router device 4. Also, after reception, a registration request packet is transmitted to the packet relay device 3 via the router device 4. As shown in FIG. 2, the packet relay device 3 confirms the validity of the transmission source of the mobile terminal 1 that has transmitted, and then notifies the mobile terminal 1 of acceptance.
[0018]
The packet relay device 3 can detect the destination of the mobile terminal 1 by registering the care-of address. Therefore, the packet relay device 3 encapsulates and relays data from the router device 4 and the file server 2 and transfers the data to the destination router device 4 through a route guided by the datagram. Note that an existing tunnel technology is used for this transfer technology (details will be described later). As shown in FIG. 3, the router device 4 transfers data to the mobile terminal 1 that is visiting.
[0019]
In the first embodiment of the present invention, in the mobile terminal 1 connected to a plurality of network interfaces connectable to the IP network, information on network interfaces other than those in communication and corresponding tunnel devices are registered in advance, The setting information of the network interface and tunnel device of the mobile terminal 1 used once is held. Thus, when the user visits the network again, the setting information is reused to shorten the time required for switching the network interface.
[0020]
This can be used, for example, in cooperation with the packet relay device 3 that relays and transfers a packet of a communication partner to ensure continuity of communication and mobility of a communication device. In other words, when one network interface is becoming unusable according to radio wave conditions, it is quickly switched to another usable network interface to ensure continuity of communication. At this time, since the network interface and the corresponding tunnel device are set in advance, the switching time is about “route table operation time + packet relay device switching time” if the number of router stages is small as shown in FIGS. Can only be shortened. If the switching time is shortened, interruption of moving image information, audio information, etc. can be prevented, and seamless mobile communication can be used.
[0021]
In addition, since the network interface and tunnel device setting information used for communication immediately before are retained, even if communication becomes impossible immediately after switching, the network interface is returned to the previous network interface. It is possible to switch.
[0022]
(Mobile terminal)
As shown in FIG. 4, the mobile terminal 1 includes an IP control unit 111, a TCP / UDP unit 112, an application unit 113, NICs 101, 102, 103, and 104, a mobile IP main control unit 201, a DHCP unit 204, and the like. .
[0023]
The IP control unit 111 includes a routing table (see FIG. 10) necessary for transferring an IP packet to a destination. The IP control unit 111 is an IP known in a known technique such as control of the routing table, IP packet fragment processing, and ICMP protocol. It is a module that performs layer (network layer) processing.
[0024]
The TCP / UDP unit 112 is a module that performs operations of known transport layers such as TCP that performs connection-oriented transmission control and UDP that does not have connectionless-oriented flow control. The packet of the TCP / UDP unit 112 is routed by the lower IP control unit 111 and transferred by one NIC among the plurality of NICs 101 to 104 according to the route table possessed by the IP control unit 111.
[0025]
The application unit 113 is various network compatible software such as FTP, HTTP, E-Mail, VoIP, streaming video playback, and the like. The application unit 113 exchanges packet data between partner communication devices via the TCP / UDP unit 112.
[0026]
The NICs 101, 102, 103, and 104 are network interface cards for radio wave wireless LAN (hereinafter referred to as “NIC”). The mobile terminal 1 can connect a plurality of types of network interfaces, such as radio wireless LAN NICs 101 and 102 compatible with IEEE802.11b, and wireless radio LAN NICs 103 and 100BASE-TX compatible with IEEE802.11a. A LAN NIC 104 that supports IEEE802.3u for wired use is used. In FIG. 4, four NICs are used, but this number can be changed according to the intended use.
[0027]
A DHCP (Dynamic Host Configuration Protocol) unit 204 acquires information on a gateway address, a domain name, a subnet mask, and other network connections, like RFC 2131 of IETF.
[0028]
The mobile IP main control unit 201 is a module that mainly controls a mobile IP protocol defined by RFC2002 or RFC3220. As shown in FIG. 5, the mobile IP main control unit 201 includes an input device 11, an output device 12, a communication control device 13, a main storage device 14, a CPU 15, a tunnel device storage device 16, a communication NIC list storage device 17, and a program storage. It is composed of the device 18 and the like. The CPU 15 includes a movement detection unit 15a, a tunnel device setting unit 15b, a switching determination unit 15c, an interface switching unit 15d, a reuse determination unit 15e, a reuse unit 15f, an agent / router request unit 15g, an agent / router advertisement unit 15h, and a registration. A request packet processing unit 15i, a registration response packet processing unit 15j, an ARP processing unit 15k, a DHCP processing control unit 151, a communication link monitoring unit 15m, and the like are provided.
[0029]
The tunnel device storage device 16 stores setting information related to a plurality of care-of addresses acquired for each NIC in order to ensure movement transparency across subnets. Specifically, as shown in FIG. 6, the tunnel device name, the corresponding NIC, the care-of-address net mask, the packet relay device destination address, the destination router default IP address or destination gateway IP address, and the mobile connection destination MAC address Memorize addresses, etc. Note that “eth0” is a temporary name that represents the NIC 101 in FIG. 4, and “eth1”, “eth2”, and “eth3” also represent the NIC 102, the NIC 103, and the NIC 104, respectively.
[0030]
For example, the top row in FIG. 6 assigns the tunnel device name “Tun_eth0” to the NIC name “eth0”. The care-of address has a net mask of 24 bits and is “192.168.10.1” (IP address), and the default router is “192.168.10.254”. In the case of wireless connection, the MAC address of the access point is stored as access point information, which means that the access point with the MAC address “00: 11: 22: 33: 44: 55” is connected. In addition to the MAC address, the “mobile connection destination” information may describe, for example, an SSID used for radio wave radio. Similarly, “eth1”, “eth2”, and “eth3” are set with care-of addresses, default routers, and the like.
[0031]
The communication NIC list storage device 17 stores information serving as a communication history such as setting information of a NIC used for communication. Specifically, the communication NIC list storage device 17 includes a memory that holds setting information set in the NIC name “eth0” used in communication. If the communication NIC list storage device 17 does not delete the setting information (see FIG. 6) of the tunnel device storage device 16 when the NIC is switched, the communication NIC list storage device 17 may have a memory configuration that simply holds the name of the NIC. For example, a memory configuration that lists up logs such as “eth0 → eth2 → eth1 → eth3” in the order used for communication may be used.
[0032]
The program storage device 18 stores a program for the CPU 15 to perform arithmetic processing.
[0033]
The movement detection means 15a detects the movement of the mobile terminal 1 by receiving an agent / router advertisement from the packet relay apparatus 3 as a home agent or the router apparatus 4 as a forensic agent and referring to a care-of address. It is a module.
[0034]
The tunnel device setting unit 15b is a module that performs creation, update, configuration of a tunnel device to be switched before switching, setting of a network interface, and the like. The configuration of the tunnel device means that an IP address which is a home address fixed to the mobile terminal 1 is assigned to the tunnel device, or a tunnel destination address (IP address of a home agent or a Foren agent) and a source address (to be described later) It refers to setting up a care-of address. This setting information is stored in the tunnel device storage device 16.
[0035]
The switching determination unit 15c is a module that refers to the movement information of the movement detection unit 15a and determines whether to switch the network interface.
[0036]
The interface switching unit 15d is a module that performs network interface switching processing. In this switching, the network interface is switched at least by operating the routing table (see FIG. 10). When switching the network interface, the configuration of the tunnel device is completed. Therefore, if the number of router stages is small as shown in FIGS. 1 to 3, the routing table operation and the mobile IP forwarding server (packet relay device 3) It is possible to switch in the time only for registration work. Further, when communication becomes impossible immediately after the NIC switching, the interface switching unit 15d refers to the communication NIC list storage device 17 and performs a process of switching again to the NIC used immediately before described in the log. .
[0037]
The reuse determining unit 15e is a module that determines whether or not the setting information of the previously visited network can be used.
[0038]
The reuse unit 15f is a module that acquires setting information of the previously visited network from the tunnel device storage device 16 or the communication NIC list storage device 17 and reuses it.
[0039]
The agent / router request means 15g creates an agent / router request for requesting an agent / router advertisement from the packet relay device 3 and the router device 4 for the purpose of obtaining information for connection to the destination network. , A module that transmits over the network. The agent / router advertisement may be periodically transmitted from the packet relay device 3 and the router device 4 or the like.
[0040]
The agent / router advertisement means 15h is a module that receives an agent / router advertisement from the packet relay apparatus 3 and the router apparatus 4 and extracts a care-of address from the advertisement. The extracted care-of address is stored in the tunnel device storage device 16. When the mobile IP (RFC2002, RFC3220) is not compliant, it is not necessary to implement a function for receiving an agent / router advertisement.
[0041]
The registration request packet processing means 15 i is a module that transmits a registration request packet for temporary registration in the destination network to the packet relay device 3.
[0042]
The registration response packet processing means 15 j is a module that receives a registration response packet from the packet relay device 3. Furthermore, the registration response packet processing means 15j determines whether or not the registration request packet has been correctly received, and if it has been correctly received, stores information on the packet in the tunnel device storage device 16. If the packet relay device 3 is not compliant with the mobile IP, at least the registration response packet processing means 15j may receive and analyze the registration request packet to ensure mobility.
[0043]
The ARP (address resolution protocol) processing means 15k is a module that acquires an unknown MAC address or the like from a known IP address. The ARP processing unit 15k may execute the Gratuitous ARP process or the ARP process at the movement destination as defined by the mobile IP.
[0044]
The DHCP processing control unit 15l activates the DHCP unit 204 to acquire a care-of address when movement is detected by the movement detection unit 15a or when a communication link is deteriorated by the communication link monitoring unit 15m. Thus, the module is controlled to be stored in the tunnel device storage device 16. If the DHCP processing control unit 15l is not installed, there is a method of using a fixed IP address that can be used in the destination network.
[0045]
The communication link monitoring unit 15m is a module that monitors a communication link state between access points.
[0046]
The input device 11 is an interface that receives an input signal from another device. The output device 12 is an interface that transmits an output signal to another device. The communication control device 13 generates and controls a control signal for transmitting and receiving data via a wireless, wired, optical fiber, or other network. The main storage device 14 temporarily stores a program describing a processing procedure and data to be processed, and delivers a machine instruction and data of the program according to a request from the CPU 15. Data processed by the CPU 15 is written to the main storage device 14. The main storage device 14 and the CPU 15 are connected by an address bus, a data bus, a control signal, and the like.
[0047]
(Tunnel device)
Here, an IP in IP tunnel defined in RFC 2003 used in mobile IP will be described with reference to FIG. On the IP in IP tunnel, since the new IP address destination and the IP address transmission source are added to the head of the original IP packet, the original IP packet is concealed. Such a tunnel is defined to be used between the mobile terminal 1 and the packet relay device 3 that is a home agent, or between the home agent and the router device 4 that is a Foren agent. .
[0048]
In the case of a UNIX (registered trademark) kernel such as Linux or FreeBSD, for example, the tunnel device is a device created to facilitate input / output of IP packets between the kernel and application software. In general, the tunnel device name, care of address, tunnel mode (IP in IP, GRE, etc.), destination address (home agent or foreign agent address) and home address of the mobile terminal 1 shown in FIG. 6 are set in the tunnel device. Thus, the tunnel function as shown in FIG. 7 can be used.
[0049]
Since the tunnel device storage device 16 can hold setting information for each NIC as shown in FIG. 6, the setting of the tunnel device is performed before acquiring a care-of address other than the communicating NIC or switching the NIC. Can be terminated.
[0050]
There are the following methods for obtaining the care-of address and the IP address of the default router gateway.
[0051]
For example, the agent / router advertisement of the router device 4 is received from the NIC 101 of FIG. In this case, since the care-of address of the router device 4 exists in the agent-router advertisement, the IP address of the router device 4 is set to the care-of address of “eth0” in FIG. 6, and the default router gateway is also the router. The IP address of the device 4 is set.
[0052]
If the agent / router advertisement is not received for a long time, the mobile terminal 1 itself transmits an agent / request packet to urge the agent / router advertisement to be issued. As a result, if an agent / router advertisement is received from the router device 4, a care-of address or a default router gateway is set.
[0053]
In a network that does not have a foreign agent such as the router device 4, the DHCP unit 204 is activated to obtain an IP address and default router gateway information from the DHCP server. The acquired IP address is set as the care-of address in FIG. The value obtained by the DHCP protocol is also set as the IP address of the default router gateway.
[0054]
(Network interface switching method)
When switching the communication NIC, the operation for reducing the number of IP address acquisitions by reusing previously set network configuration information will be described with reference to the flowchart of FIG. The following operation will be described on the assumption that it is necessary to switch the network to which the mobile terminal 1 belongs because of movement.
[0055]
(A) First, in step S101, as the mobile terminal 1 moves, the movement detection unit 15a determines a NIC to be switched. When a plurality of types of NICs are connected, the switching determination unit 15c needs to determine which NIC to switch to. As a criterion for this determination, for example, when IEEE802.11b, IEEE802.11a, and IEEE802.3u are connected to the NIC, IEEE802.3u, IEEE802.11a, and IEEE802.11b are given priority in descending order of data transfer speed. It is preferable that a NIC having a high data transfer rate is selected. Further, as shown in FIG. 4, if two or more of the same kind of IEEE802.11b NICs (NIC 101 and NIC 102) are connected, it may be determined to switch the NIC having a high radio wave intensity as the communication NIC.
[0056]
(B) Next, in step S102, the reuse determining unit 15e confirms whether the NIC to be switched can use the same network setting information used previously. Assume that “eth0” is communicating in the setting state as shown in FIG. 6 and the NIC to be switched is “eth1”. “Eth1” receives a beacon signal, a router advertisement, and the like from the access point to be connected, and obtains the MAC address (MAC-AP) of the access point. Compare this MAC-AP value with the MAC address in the setting information field of “eth1” shown in FIG. 5 (“11: 22: 33: 44: 55: 00” in the example of FIG. 6), and match Judge whether to do. If they match, it is determined that there is a possibility of reuse, and the process proceeds to step S104. If they do not match, it is determined that there is no possibility of reuse, and the process proceeds to step S103.
[0057]
(C) In step S104, the reuse determining unit 15e checks whether the setting information is within the validity period. If it is within the expiration date, it is determined that it can be reused, and the process proceeds to step S105. If it is outside the expiration date, it is determined that it cannot be reused, and the process proceeds to step S103. Here, within the validity period, for example, if the DHCP unit 204 is activated and the setting information is acquired, it is confirmed whether it is within the lease period as stipulated by the DHCP protocol. In addition, it is confirmed whether a registration request packet, which will be described later, is within the expiration date as stipulated in Mobile IP. If the expiration date is infinite, step S104 may be omitted.
[0058]
(D) In step S103, for example, “eth1” cannot use previous setting information such as when trying to connect to an access point “aa: bb: cc: dd: ee: ff” different from FIG. If the setting information is outside the expiration date, the tunnel device setting unit 15b, the agent / router advertisement unit 15h, etc. newly acquire the setting information. Details will be described later.
[0059]
(E) In step S105, since the setting information can be reused, the setting information is referred to the previous setting information (see FIG. 6) held in the tunnel device storage device 16 or the communication NIC list storage device 17. To get.
[0060]
(F) Finally, in step S106, after acquiring the setting information, the interface switching unit 15d performs a process of actually switching the NIC. This switching process will be described later.
[0061]
Next, the setting information acquisition operation in step S103 in FIG. 8 will be described with reference to the flowchart in FIG.
[0062]
(A) In step S201, the agent / router advertising means 15h confirms whether an agent / router advertisement is received. If the agent / router advertisement has been received, since the IP address of the router device 4 or the packet relay device 3 included in the advertisement is included, the process proceeds to step S202. If the agent / router advertisement has not been received, the process proceeds to step S203.
[0063]
(B) In step S202, the tunnel device setting unit 15b updates the care-of address and the IP address of the default router gateway as the setting information using the advertisement information and the setting information.
[0064]
(C) In step S203, the DHCP process control unit 15l activates the DHCP unit 204 to acquire an IP address (care of address). In step S204, it is confirmed as a result of the acquisition whether the IP address has been obtained from the DHCP server or has failed due to a timeout or the like. If the IP address has been obtained correctly, the process proceeds to step S202. If the IP address cannot be obtained correctly, the process proceeds to step S205.
[0065]
(D) In step S205, the agent / router request unit 15g issues an agent request, and the agent / router advertisement unit 15h confirms whether the care-of address has been acquired. If the care-of address has been acquired, the process proceeds to step S202. If not acquired, the process proceeds to step S206.
[0066]
(E) In step S206, an error flag is set. If acquisition of the IP address fails in step S203, an agent request is issued to urge agent router advertisement issuance. As a result of issuing the agent request in step S205, if there is a response of the agent / router advertisement, the setting information is updated in step S202. If there is no response, an error flag is set. At this time, it is desirable not to update the setting information.
[0067]
As described above, the setting information of the tunnel device storage device 16 shown in FIG. 6 is updated. In FIG. 9, an attempt is made to obtain a care-of address in the order of confirmation of reception of an agent / router advertisement in step S201, activation of the DHCP unit 204 in step S203, and issuance of an agent request in step S205. The order is not particularly limited, and can be freely determined from the relationship with other devices in the system.
[0068]
Next, the NIC switching process by the route table operation in step S106 in FIG. 8 will be described. Although physical wiring may be changed to switch the NIC, it is desirable to change the NIC by manipulating the routing table managed by the IP control unit 111 in FIG. In general, when an application that operates on a device equipped with a plurality of NICs transmits data using the TCP / IP protocol, the application does not determine NICs 101 to 104 to be used by itself, and a TCP / IP protocol called a routing table. Follow the description of the database installed on the stack. That is, the NICs 101 to 104 to be used by the TCP / IP communication application can be specified by controlling the routing table.
[0069]
As shown in the route table before the change in FIG. 10A, the route table includes “Destination” that is the IP address that is the destination of the data packet, “Gateway” that is the IP address of the gateway, and “Genmask” that indicates the netmask. "Flags" indicating flags, "MSS" specifying the maximum segment size in the route, "Window" specifying the window size in TCP, "irtt" specifying the initial round trip time of TCP in the route, interface used It is a database that designates “Iface”, which is the name of the NICs 101-104.
[0070]
The upper part of the route table before the change in FIG. 10A means that the data packet of the netmask “255.255.255.0” with the IP address “192.168.0.0” uses the NIC “eth0” to transmit data. Normally, the higher the priority is in the database at the top of the route table, the data is transmitted using the matching transfer means. If it does not match, the next database is referenced. For example, a data packet addressed to the IP address “192.168.0.100” matches the uppermost database and is transferred using the NIC “eth0”.
[0071]
The database for the IP address “127.0.0.0” in the next stage in FIG. 10A is a basic definition necessary for looping back a packet inside the mobile terminal (local). That is, the data packet addressed to the netmask “255.0.0.0” with the IP address “127.0.0.0” uses the interface “lo” indicating the loop. Further, the lowermost level means that the IP address “0.0.0.0”, that is, all the data packets that do not match the upper level are transferred to the gateway “192.168.0.1” using the NIC “eth0”. From the route table before the change in FIG. 10A, it can be seen that the IP network using the NIC “eth0” is the subnet of “192.168.0.0” and the netmask “255.255.255.0”.
[0072]
Subsequently, a route table operation for switching the NICs 101 to 104 will be described with reference to the example after the route table change in FIG. The changed routing table in FIG. 10B shows an example for switching the NIC from “eth0” to “eth1”, where “eth1” is “192.168.1.0” and the netmask is “255.255.255.0”. Assume that a subnet is used. Here, it is assumed that the IP address of the packet relay device is “192.168.0.230”, further “192.168.1.0”, and the default gateway in the netmask “255.255.255.0” is “192.168.1.254” (FIGS. 1 to 3). reference).
[0073]
The purpose of the first row of the route table in FIG. 10B is to correct or add a route addressed to the packet relay device 3. The data packet addressed to the packet relay device 3 “192.168.0.230” is set to use the NIC “eth1” to be switched with the gateway set to “192.168.1.254”. By adding this line, a “registration request packet” addressed to the packet relay device 3 can be transmitted.
[0074]
The purpose of the second row of the route table in FIG. 10B is to modify or add the route of the network to which the NIC “eth1” is connected. This is because the data packet with the destination “192.168.1.0” and the netmask “255.255.255.0” uses the NIC “eth1”, and this line need not be added. The third to fourth rows of the route table in FIG. 10B depend on the route before the change. In addition, since it has the same meaning as the upper stage and the next stage in FIG. However, the third line may be deleted.
[0075]
The purpose of the fifth line of the route table in FIG. 10B is to modify and add a route so that data packets other than those described above pass through the tunnel device. This means that the IP address “0.0.0.0”, that is, all data packets that do not match the upper row are transferred using the interface “tun_eth1” as the gateway “192.168.0.230”. The gateway of the tunnel device preferably specifies the IP address of the packet relay device. “Tun_eth1” is the tunnel device shown in FIG. 6, and it is necessary to finish setting of the tunnel device before adding this line.
[0076]
In the first embodiment of the present invention, the routing table is operated, and the data packet transmitted by the application is finally set to be always transmitted via the tunnel device.
[0077]
By manipulating the routing table in this way, the flow of data packets can be controlled as shown in FIG. That is, before the routing table is changed, the data packet from the application is controlled via the NIC “eth0”, and after the routing table is changed, an IP in IP tunnel packet is generated by the tunnel device, and data is transmitted using the NIC “eth1”. Controlled so that packets are forwarded. Similarly, when switching to “eth2”, “eth3”, or the like, the NIC can be switched by operating the routing table.
[0078]
Next, the actual control flow (step S106 in FIG. 8) will be described with reference to FIG.
[0079]
(A) First, in step S301, the tunnel device setting unit 15b sets an IP address to the NICs 101 to 104 to be switched, that is, a process of assigning a care-of address to the NICs 101 to 104, or a default router / default gateway setting. Further, the source IP address, the destination IP address, etc. of the tunnel device are set.
[0080]
(B) In step S302, the interface switching unit 15d operates the route table so that the registration request packet can reach the packet relay device 3 correctly when transmitting the registration request packet. Specifically, the operation of the routing table is performed by setting the first row described after the routing table is changed in FIG.
[0081]
(C) In step S 303, the registration request packet processing means 15 i transmits a registration request packet to the packet relay device 3. Thereafter, in step S304, reception of a registration response packet from the packet relay device is awaited, and the registration response packet processing means 15j determines whether the registration request packet has been correctly received after reception. If the registration request packet is correctly received, the process proceeds to step S305, and the operation on the fifth line described after the change of the route table in FIG. 10B is performed, and the route table operation for switching the communication NICs 101 to 104 is performed. Finalize. If the registration request packet is not correctly received, the process proceeds to step S306, and error processing such as performing the route operation in step S302 again is performed.
[0082]
According to the above switching process, the flow of the data packet is controlled by the operation of the routing table by the interface switching unit 15d, so that the logical NICs 101 to 104 can be switched by software control.
[0083]
When starting the switching process of FIG. 12, it may be checked whether the error flag shown in step S206 of FIG. 9 is set. In this case, since appropriate setting information cannot be set in the NICs 101 to 104 or the tunnel device, it is preferable not to perform the series of switching processes in FIG. Furthermore, a flow other than the switching process shown in FIG. 12 may be used. For example, step S305 may be performed after step S302. In this case, in the error process of step S306, it is desirable that the process of step S305 is also performed.
[0084]
Thus, in the first embodiment of the present invention, it is determined whether or not the previous setting information can be effectively reused (steps S102, S104, etc.). For this reason, even if the mobile terminal 1 moves frequently on the network, the IP address can be reused if the network has visited once, and thus high-speed processing of mobile communication becomes possible.
[0085]
(Example of change)
In the switching process according to the first embodiment of the present invention, the radio wave wireless strength and the optical link signal do not become unstable immediately after switching the communication NICs 101 to 104, so that the NICs 101 to 104 used immediately before are smoothly switched. It is preferable to provide a function for switching again and a flow process.
[0086]
As shown in FIG. 13, the communication NIC list storage device 17 is updated (step S407) after the switching process in step S106 of FIG. That is, the setting information of the NICs 101 to 104 used in the previous communication is stored in the communication NIC list storage device 17. Thus, the communication NIC list storage device 17 can be referred to and the NICs 101 to 104 or the NIC list in the order used for communication can be known. Since steps S401 to S406 are the same as steps S101 to S106, description thereof is omitted.
[0087]
The update operation of the communication NIC list storage device 17 will be described with reference to the flowchart of FIG.
[0088]
(A) In step S501, the communication link monitoring unit 15m confirms communication resistance such as whether the communication status of the communication NICs 101 to 104 has deteriorated or the communication link status has deteriorated. If the communication link status is not appropriate as a result of the confirmation, loop processing from step S502 is performed until the appropriate link status is reached. If there is no abnormality as a result of the confirmation, the process ends without doing anything.
(B) In step S503, the interface switching unit 15d refers to the memory held in the communication NIC list storage device 17. The communication NIC list storage device 17 includes the name of the communication NIC used at least one time ago. From the NIC name, the setting information of FIG. 6 held by the tunnel device storage device 16 is referred to, and the NICs 101 to 104 and the tunnel device setting information used previously (care-of-address, default router / default gateway, etc.) ).
[0089]
(C) In step S504, the interface switching unit 15d performs switching processing of the NICs 101 to 104 based on the setting information of the communication NICs 101 to 104 used immediately before. Since this switching process is the same as that described in step S106 (see FIG. 12) in FIG. 8, a description thereof will be omitted.
[0090]
(D) In step S505, the communication link monitoring unit 15m confirms the link status of the communication NICs 101 to 104 again. If the communication status is significantly deteriorated even after switching to the immediately preceding communication NIC 101-104, it is confirmed whether the previous list of communication NICs 101-104 cannot be used. Specifically, a series of operations in steps S502 to S506 are looped.
[0091]
(E) In step S506, if the communication status is improved, this flow processing is terminated.
[0092]
According to the modification of the first embodiment of the present invention, since the setting information is stored in the tunnel device storage device 16 and the log of the movement route is also stored in the communication NIC list storage device 17, the movement destination Even if the communication status of the network is unstable, it is possible to immediately connect to the network to which it previously belonged. As a result, the communication link status can be stabilized and the affinity to the external network can be increased.
[0093]
In the first embodiment of the present invention, the mobile terminal 1 in FIGS. 1 to 3 communicates with one file server 2 using any one of the NICs 101 to 104 in FIG. It is explained as a premise. However, in actual communication, a plurality of file servers 2 and a plurality of NICNICs 101 to 104 may communicate simultaneously. Even in this case, the setting information stored in the tunnel device storage device 16 can be used to prevent multiple network interfaces from connecting to overlapping subnets or the same access point, thereby speeding up communication processing. is there. Details will be described below in the second embodiment.
[0094]
(Second Embodiment)
A communication system using the mobile terminal 1a according to the second embodiment of the present invention will be described with reference to FIG.
[0095]
The mobile terminal 1 a of this communication system connects the NIC 101 and the NIC 102. The NIC 101 and NIC 102 are IEEE802.11b compatible wireless interfaces. In the communication system, file servers 2a and 2b for distributing information to the mobile terminal 1a are arranged, and each includes access points AP-1 and AP-2 compatible with IEEE802.11b. These two networks are distinguished by the router device 4a.
[0096]
In the above communication system, there may occur a situation in which the NIC 101 and the NIC 102 of the mobile terminal 1a are connected only to the same access point AP-1. In this case, there is a possibility that connection to the file server 2b in the AP-2 network is not possible.
[0097]
Therefore, when the NIC 101 is connected to the access point AP-1, the NIC 102 is set to be connected to an access point different from the access point AP-1, that is, the access point AP-2 in FIG. This is realized by selecting access points so that the “mobile connection destination” in the setting information of FIG. 6 does not overlap. Thereby, the convenience at the time of connecting a plurality of NICs is improved.
[0098]
(Mobile terminal)
As shown in FIG. 4, the mobile terminal 1a includes an IP control unit 111, a TCP / UDP unit 112, an application unit 113, NICs 101, 102, 103, and 104, a mobile IP main control unit 201, a DHCP unit 204, and the like. . In addition, since apparatuses other than the mobile IP main control unit 201 are the same as those in the first embodiment, description thereof is omitted.
[0099]
As shown in FIG. 16, the mobile IP main control unit 201a (201) includes an input device 21, an output device 22, a communication control device 23, a main storage device 24, a CPU 25, a tunnel device storage device 26, and a communication NIC list storage device 27. And a program storage device 28 and the like. The CPU 25 includes a movement detection unit 25a, a tunnel device setting unit 25b, a switching determination unit 25c, an interface switching unit 25d, a reuse determination unit 25e, a reuse unit 25f, an agent / router request unit 25g, an agent / router advertisement unit 25h, and a registration. Request packet processing means 25i, registration response packet processing means 25j, ARP processing means 25k, DHCP processing control means 25l, access point information acquisition means 25m, network interface determination means 25n, mobile connection destination determination means 25o, and the like.
[0100]
The access point information acquisition unit 25m is a module that acquires signals from the access points AP-1 and AP-2. Note that the access point signal may use any communication medium such as radio wave, optical radio, and wired cable. The network interface determination unit 25n is a module that determines whether the same type of NIC is already connected to the access points AP-1 and AP-2. The mobile connection destination determination unit 25o is a module that determines a candidate access point that is the next mobile connection destination. Since other devices are the same as those in the first embodiment, description thereof is omitted.
[0101]
(Network interface switching method)
Hereinafter, mobile connection destination selection processing for avoiding duplication of access points will be described with reference to FIG. This selection process is preferably performed in addition to step S101 in FIG.
[0102]
(A) First, in step S601, the access point information acquisition unit 25m acquires information on the access points AP-1 and AP-2 that can be used for communication. The information of the access points AP-1 and AP-2 is information obtained from a beacon signal and includes at least a MAC address. In addition, radio wave intensity, noise level, SSID, and the like may be acquired.
[0103]
(B) In step S602, the network interface determination unit 25n confirms whether the same type of NIC is already connected. If it is not connected, the process proceeds to step S603, where it is selected as a candidate for the mobile connection destination access points AP-1 and AP-2. If it is already connected, the process proceeds to step S604, and whether or not the access point is AP-1 or AP-2 already used is referred to and compared with the setting information of FIG. As a result of the comparison, if it is an access point not shown in FIG. 6, that is, an access point that has not been used yet, the process proceeds to step S603, and the mobile connection destination determination means 25o selects the access point as a mobile connection destination candidate. On the other hand, if it is determined that it is used, this processing flow ends.
[0104]
According to the second embodiment of the present invention, even when a plurality of access points and a plurality of NICs 101 to 104 communicate simultaneously, the setting information stored in the tunnel device storage device 16 is referred to. Thus, a plurality of network interfaces can be prevented from connecting to the same access point that is duplicated. Thereby, speeding up of communication processing can be achieved.
[0105]
Also, when two NICs are used, as shown in FIG. 18A, when two IEEE 802.11b NICs are connected, as shown in FIG. 18B, IEEE 802.11a and IEEE 802.11b. In the case of connecting a NIC, a configuration in which an IEEE802.11b and a 100BASE-TX NIC are connected as shown in FIG. The types of network interfaces are not limited to these, and radio waves, infrared radios (optical radios) NICs, and the like that can be connected to the IP network can also be used.
[0106]
The setting information in the tunnel device storage device 16 used in the first embodiment and the second embodiment must be periodically cleared to 0 before overflow. The timing at which this setting information is updated to an invalid value is preferably when the access point set in each NIC becomes unusable, such as a radio wave situation or a link situation. Specifically, there are cases where beacon information is no longer received, radio wave strength is below a certain threshold, optical wireless link signals are lost, and the like.
[0107]
Furthermore, devices, system configurations, methods, standards, and the like used in the embodiments of the present invention are examples, and the present invention is of course not limited thereto.
[0108]
【The invention's effect】
According to the present invention, it is possible to provide a mobile terminal and a network interface switching method capable of performing high-speed switching and having high compatibility with an external network by setting a network interface and a tunnel device to be switched in advance. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a system using a mobile terminal according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram of a system using a mobile terminal according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram of a system using a mobile terminal according to the first embodiment of the present invention.
FIG. 4 is an internal configuration diagram of a mobile terminal according to the first embodiment of the present invention.
FIG. 5 is an internal configuration diagram of a mobile IP main control device.
FIG. 6 is a data configuration diagram of setting information in a tunnel device storage device.
FIG. 7 is a schematic diagram showing an example of a tunnel device structure.
FIG. 8 is a flowchart showing an operation of the network interface switching method according to the first exemplary embodiment of the present invention.
FIG. 9 is a flowchart showing an operation for acquiring setting information.
FIG. 10 is a diagram illustrating an example of a route table.
FIG. 11 is a schematic diagram showing a flow of a data packet when passing through a tunnel device.
FIG. 12 is a flowchart showing an operation of a switching process.
FIG. 13 is a flowchart showing an operation of the network interface switching method according to the first exemplary embodiment of the present invention.
FIG. 14 is a flowchart showing an operation of updating the communication NIC list storage device.
FIG. 15 is a schematic diagram of a system using a mobile terminal according to a second embodiment of the present invention.
FIG. 16 is an internal configuration diagram of the mobile IP main control device.
FIG. 17 is a flowchart showing the operation of a mobile connection destination selection process.
FIG. 18 is a schematic diagram showing how the network interface is used.
FIG. 19 is a schematic diagram illustrating an operation in which a mobile terminal moves between different networks.
[Explanation of symbols]
1, 1a ... mobile terminal
2 ... File server
2 ... Router device
3. Packet relay device
4, 4a ... Router device
6 ... Network
11 ... Input device
12 ... Output device
13. Communication control device
14 ... Main memory
15 ... CPU
15a ... Movement detection means
15b ... Tunnel device setting means
15c ... Switching judgment means
15d: Interface switching means
15e ... Reuse determination means
15f ... Reuse means
15g ... Router request means
15h ... Router advertisement means
15i ... Registration request packet processing means
15j ... Registration response packet processing means
15k ... ARP processing means
15l ... DHCP processing control means
15m ... Communication link monitoring means
16 ... Tunnel device storage device
17 ... Communication NIC list storage device
18 ... Program storage device
21 ... Input device
22 ... Output device
23. Communication control device
24. Main memory device
25 ... CPU
25a ... Movement detection means
25b ... Tunnel device setting means
25c: switching determination means
25d: Interface switching means
25e ... Reuse determination means
25f ... Reuse means
25g ... Router request means
25h ... Router advertisement means
25i ... Registration request packet processing means
25j ... Registration response packet processing means
25k ... ARP processing means
25l ... DHCP processing control means
25m ... access point information acquisition means
25n ... Network interface judgment means
25o ... Mobile connection destination determination means
26 ... Tunnel device storage device
27 ... List storage device
28 ... Program storage device
111 ... IP control unit
112 ... TCP / UDP part
113 ... Application section
201, 201a: Mobile IP main control unit
204 ... DHCP part

Claims (6)

A setting means for setting information relating to an IP tunnel, which is a predefined communication procedure, for each of at least one or more network interfaces;
Storage means for storing setting information for each setting of the IP tunnel;
A movement detecting means for receiving an agent / router advertisement via the network interface and detecting movement of the own terminal;
Reuse determination means for determining whether the setting information of the network interface to be switched after detection of the movement has been previously set and is reusable with reference to the setting information in the storage means;
Reusable means for reusing the setting information of the network interface when it is determined that it can be reused;
A mobile terminal comprising: interface switching means for switching the network interface by operating at least a route table indicating a route of communication data when reusing the setting information of the network interface. Communication NIC list storage means for storing a history of switching of the network interface;
Communication link monitoring means for monitoring the state of the communication link of the network related to the network interface,
The interface switching unit refers to the history of the communication NIC list storage unit and switches to the network interface used immediately before when the communication state of the network interface of the switching destination deteriorates immediately after the switching. The mobile terminal according to claim 1. Network interface determination means for determining whether the same type of network interface is already connected to an access point that is a mobile connection destination;
A mobile connection destination determination means for determining a candidate for the next access point to be the next mobile connection destination when a memory card that already stores information on the network interface of the same type is connected;
The interface switching unit switches the network interface so as to correspond to the access point that is a candidate when the next access point candidate is determined by the mobile connection destination determination unit. Or the mobile terminal of 2. Setting information on an IP tunnel, which is a predefined communication procedure, for each of at least one or more network interfaces;
Storing the setting information in the storage means for each setting of the IP tunnel;
Receiving an agent-router advertisement via the network interface and detecting the movement of the terminal;
Determining, after the detection of the movement, whether the setting information of the network interface to be switched has been previously set and is reusable with reference to the setting information in the storage means;
Reusing the setting information of the network interface when it is determined that the network interface can be reused;
When reusing the setting information of the network interface, switching the network interface by operating at least a route table indicating a route of communication data;
And a step of updating the setting information used in communication and storing it in the storage means when switching the network interface. Storing the network interface switching history in a communication NIC list storage means;
Monitoring a state of a communication link of a network related to the network interface,
The step of switching the network interface refers to the network interface used immediately before by referring to the history of the communication NIC list storage means when the communication state of the switching destination network interface deteriorates immediately after the switching. 5. The network interface switching method according to claim 4, wherein the network interface switching method is performed. Determining whether the same type of network interface is already connected to an access point that is a mobile connection destination;
A step of determining a next access point candidate to be a next mobile connection destination when a memory card that already stores information on the same type of network interface is connected;
The network interface switching step according to claim 4 or 5, wherein when the next access point candidate is determined, the network interface is switched to correspond to the candidate access point. Network interface switching method.

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