JP2004363755A - Communication device, packet replaying device, and the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication device, a packet relaying device and the like capable of maintaining a communication session even if an address changes during the continuation of the communication session. <P>SOLUTION: A non-mobile type communication device which is connected to a network and carries out packet communication with the other communication equipment through a packet relaying device acquires an address to which the validity date of the communication device is given and informs the packet relaying device of the address through the network. Then the communication device acquires a new address before the validity date of the address expires, decides whether the newly acquired address has been changed from the address which is already acquired, and reports the newly acquired address to the packet relaying device when the address has been changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
A non-mobile communication device that is connected to a network and performs packet communication with another communication device, and a packet relay device that relays a packet exchanged between the communication device and the other communication device, The present invention relates to a technical field such as a network system including
[0002]
[Prior art]
2. Description of the Related Art In recent years, not only in company offices but also in general households, peripheral devices such as personal computers (hereinafter, referred to as “PCs”), printers, and network-compatible AV (Audio Visual) devices have been connected to LANs (Local Area Networks). ) Is being built. Further, a router and gateway devices such as a home gateway and a home server are connected to such a LAN, and are generally connected to an external network such as the Internet via these devices.
[0003]
When the gateway device connects to the Internet, the IP (Internet Protocol) address of the gateway device is generally dynamically assigned with a time limit by a DHCP (Dynamic Host Configuration Protocol) server of an ISP (Internet service provider), It is reacquired after the expiration of the deadline, and the assigned IP address often changes each time it is acquired.
[0004]
A dynamic DNS (Domain Name System) server system is known as a system for coping with such a change in the IP address. This dynamic DNS server system is connected to the Internet and registers the IP address of the gateway device in association with an FQDN (fully qualified domain name: fully qualified domain name) that is the identification name of the gateway device. Each time the IP address changes, the association is updated. Accordingly, for example, when a user uses a resource (PC, AV device, or content such as video and audio data included in the device and the like) connected to a LAN at home from a remote place by using a communication device such as a mobile device, the communication is performed. The device first obtains the current IP address of the gateway device by making an inquiry to the server of the dynamic DNS by designating the FQDN, and can establish a communication session with the gateway device via the Internet.
[Patent Document 1]
JP-A-2002-305531
Patent Document 1 discloses an example of such a dynamic DNS server system.
[0005]
[Problems to be solved by the invention]
However, in such a conventional system, when the communication session is established and the communication device is connected to the gateway device via the Internet and the IP address of the gateway device changes, the communication session is disconnected. In some cases, communication could not be continued. In particular, the ongoing communication operation is interrupted when the communication device receives video or audio streams or performs mutual communication, or when transferring a large-capacity file that takes a long time to transfer. That is very inconvenient.
[0006]
In view of the above, an object of the present invention is to provide a communication device capable of maintaining a communication session even if the address changes during the continuation of the communication session, a packet relay device, and the like. I do.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, a communication device according to claim 1 is a non-mobile communication device that is connected to a network and performs packet communication with another communication device via a packet relay device. Address acquisition means for acquiring an address to which a use expiration date (use expiration date) of the communication device is assigned; and address notifying means for notifying the packet relay device of the address via the network, wherein the address acquisition means Before the expiration date of the address (expiration date) elapses, a new address is acquired, and the address notifying means determines whether or not the newly acquired address has changed from the already acquired address. If the address is changed, the newly obtained address is notified to the packet relay apparatus.
[0008]
The network system according to claim 12, wherein the network system is connected to a network, performs non-mobile communication devices that perform packet communication with other communication devices, and is exchanged between the communication devices and the other communication devices. A packet relay device for relaying a packet to the communication device, wherein the communication device obtains an address to which its own expiration date is assigned, and notifies the packet relay device of the address via the network. The packet relay device registers the address notified from the communication device as an address of the communication device on the network, and the communication device transmits the address before the expiration date of the address. To obtain a new address and determine whether the address has changed from the address already obtained. If the address has changed, the newly obtained address is notified to the packet relay device, and the packet relay device notifies the registered address of the newly obtained address notified from the communication device. It is characterized in that it is updated to the acquired address.
[0009]
The communication method according to claim 13, wherein the communication method is a communication method in a non-mobile communication device that is connected to a network and performs packet communication with another communication device via a packet relay device. Obtaining an address with an expiration date and notifying the packet relay device of the address via the network; and obtaining a new address before the expiration date of the address elapses and obtaining a new address. Determined whether the obtained address has changed from the already obtained address, and when the address has changed, notifying the packet relay device of the newly obtained address, It is characterized by having.
[0010]
The communication method according to claim 14 is a communication method in a packet relay device that is connected to a network and relays a packet exchanged between the communication device according to claim 2 and another communication device, Registering the address given the expiration date notified from the communication device as the address of the communication device on the network, and further, if a new address is notified from the communication device, the registered Updating the new address to the new address.
[0011]
The communication method according to claim 15, wherein the non-mobile communication device is connected to a network and performs packet communication with another communication device, and is exchanged between the communication device and the other communication device. And a packet relay device for relaying a packet to the network device, wherein the communication device obtains an address to which its own expiration date is assigned, and transfers the address to the packet relay device via the network. Notifying the device, the packet relay device, registering the address notified from the communication device as an address of the communication device on the network, the communication device, the expiration date of the address Before the elapse, a new address is acquired, and it is determined whether the address has changed from the address already acquired. Separately, when the address has changed, the step of notifying the newly obtained address to the packet relay device, and the packet relay device notifies the registered address from the communication device. And updating the newly acquired address to the newly acquired address.
[0012]
The communication processing program according to claim 16, further comprising: connecting a computer included in a non-mobile communication device that performs packet communication with another communication device via a packet relay device to a communication device. Address acquisition means for acquiring an address to which the expiration date has been given, and address notifying means for notifying the packet relay device of the address via the network, and further functioning as the address acquisition means, Before the expiration date, a new address is obtained, and the address notifying means determines whether the newly obtained address has changed from the already obtained address, and the address is changed. In the case of having, it is made to function to notify the packet relay device of the newly obtained address. That.
[0013]
The communication processing program according to claim 17, wherein the computer included in a packet relay device that relays a packet exchanged between the communication device according to claim 2 and another communication device is connected to a network. Register the address given the expiration date notified from the communication device, as the address of the communication device on the network, further, if a new address is notified from the communication device, the registered address Is updated to the new address.
[0014]
A recording medium according to claim 18 is characterized in that the communication processing program according to claim 16 or 17 is recorded in a computer-readable manner.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to the drawings. The embodiment described below is an embodiment in which the present application is applied to a network system.
[0016]
(1st Embodiment)
First, a configuration and functions of a network system according to a first embodiment of the present invention will be described with reference to FIG.
[0017]
FIG. 1 is a diagram illustrating a schematic configuration example of a network system SX1 according to the first embodiment. As shown in FIG. 1, the network system SX1 is roughly divided into a fixed host 1, an ISP (including a server, a router, and the like) 2, an example of a non-mobile communication device of the present application, a packet relay device 3, and An external host (for example, a mobile device such as a mobile phone or a PDA) 4 as an example of another communication device is included.
[0018]
The ISP 2 and the packet relay device 3 are connected to the Internet 5 as an example of the network of the present application, and the external host 4 can be connected to the Internet 5 via a wireless base station, a mobile communication line, or the like. Further, a DHCP server 2a is connected to the ISP 2, and the DHCP server 2a assigns an IP address to which an expiration date is given to the fixed host 1.
[0019]
The fixed host 1 is mainly configured by a CPU (Central Processing Unit) as a computer that executes various arithmetic processing and control processing, and stores a program (including a communication processing program of the present application) and a storage unit (for example, a data processing program). ROM, RAM, hard disk, etc.), and a communication unit for performing mutual conversion between communication data and an electric signal when performing communication with the outside. The CPU executes the above-described program to provide gateway and server functions, It has functions as a DHCP client 11, an IP tunnel processing unit 12, and an application unit 13. The communication processing program may be downloaded from a predetermined server via the Internet 5 or read from a recording medium such as a CD-ROM, and stored in the storage unit of the fixed host 1.
[0020]
The DHCP client 11 functions as an address acquisition unit of the present application, requests an available address from the DHCP server 2a via the ISP 2, and acquires the address. The acquired address is set so that the fixed host 1 can connect to the Internet 5 via the ISP 2. The address at which the fixed host 1 connects to the Internet 5 is hereinafter referred to as "real address". Further, the DHCP client 11 acquires a new available address from the DHCP server 2a before the expiration date of the set real address elapses, and sets it as the real address.
[0021]
The application unit 13 includes a mechanism for storing transmission data in an IP packet and extracting received data from an IP packet for an application available from the external host 4 and data transmitted and received by the application. Applications that can be used from the external host 4 include file transfer over the Internet, streaming transmission of AV content, communication by IP telephone with a fixed host, and use of general computation resources. Further, the application unit 13 generates an original IP packet, adds a header having an IP address of the external host 4 as a destination and a unique address corresponding to the application as a transmission source to the original IP packet, and outputs the packet to the IP tunnel processing unit 12. It has a function to do. This unique address is an IP address specified when the application is used from the external host 4. In the first embodiment, it is assumed that this unique address is a global address that can be directly accessed from the Internet 5.
[0022]
Here, the original IP packet refers to an IP packet that is not encapsulated. The IP packet includes an original IP packet and an encapsulated IP packet.
[0023]
The IP tunnel processing unit 12 has a function as an address notification unit, a packet encapsulation unit, a packet extraction unit, a packet transmission unit, a packet reception unit, and the like of the present application. More specifically, the IP tunnel processing unit 12 functions as an address notifying unit, and notifies the packet relay device 3 of the real address via the ISP 2, the Internet 5, and the like. Thereby, an IP tunnel is established between the fixed host 1 and the packet relay device 3.
(Composition). Further, the IP tunnel processing unit 12 determines whether or not the newly acquired real address has changed from the already acquired real address, and if the real address has changed, the newly acquired real address has changed. The acquired real address is notified to the packet relay device 3. As a result, the IP tunnel is reconfigured.
[0024]
Further, the IP tunnel processing unit 12 functions as a packet encapsulation unit, and further, for the original IP packet output from the application unit 13, furthermore, the IP address of the packet relay device 3 as the destination and the real address as the transmission source. Is added and encapsulated. Then, the IP tunnel processing unit 12 functions as a packet transmission unit, and transmits the encapsulated IP packet to the packet relay device 3 via the ISP 2 or the like to the Internet 5.
[0025]
Further, the IP tunnel processing unit 12 functions as a packet receiving unit, and receives an IP packet transmitted from the packet relay device 3 via the ISP 2 or the like. Then, the IP tunnel processing unit 12 functions as a packet extracting unit, extracts (takes out) an original IP packet from an IP packet from the packet relay device 3, and outputs this to the application unit 13.
[0026]
Next, the packet relay device 3 relays an IP packet exchanged between the fixed host 1 and the external host 4, and although not shown, a CPU as a computer that executes various arithmetic processes and control processes. A storage unit (for example, a ROM, a RAM, a hard disk, or the like) that is configured as a main body and stores a program (including the communication processing program of the present application) and data; A communication unit for performing conversion is provided. The CPU of the packet relay device 3 has a function as the IP tunnel management unit 31 and the like. The communication processing program of the present application may be downloaded from a predetermined server via the Internet 5 or read from a recording medium such as a CD-ROM and stored in the storage unit of the packet relay device 3. Good.
[0027]
The IP tunnel management unit 31 has functions as an address registration unit, a packet reception unit, a packet extraction unit, a packet encapsulation unit, a packet transmission unit, and the like of the present application. More specifically, the IP tunnel management unit 31 functions as the address registration unit of the present application, and registers the real address notified from the fixed host 1 in an updatable manner as the address of the fixed host 1 on the Internet 5. It has become.
[0028]
When an IP packet addressed to itself (encapsulated IP packet) is transmitted from the fixed host 1, the IP tunnel management unit 31 functions as a packet receiving unit, a packet extracting unit, and a packet transmitting unit. An IP packet is received, an original IP packet is extracted therefrom, and the original IP packet is transmitted to the external host 4 to the Internet 5.
[0029]
On the other hand, when an IP packet addressed to the unique address corresponding to the application unit 13 operating on the fixed host 1 is transmitted from the external host 4, the packet relay device 3 receives the IP packet, and further, The packet is encapsulated by adding a header having the real address of the fixed host 1 and the IP address of the packet relay device 3 as the transmission source, and sending it to the fixed host 1 to the Internet 5.
[0030]
Next, the operation of the network system SX1 having the above configuration will be described.
[0031]
First, an operation when an IP tunnel between the fixed host 1 and the packet relay device 3 is configured or reconfigured will be described with reference to FIGS.
[0032]
FIG. 2A is a flowchart illustrating processing of the fixed host 1 when an IP tunnel is configured or reconfigured, and FIG. 2B is a flowchart illustrating processing of the packet relay device 3 in that case. FIG. 3 is a diagram showing a state in which an IP address is notified from the fixed host 1 to the packet relay device 3.
[0033]
In the process of FIG. 2A, first, the fixed host 1 accesses the DHCP server 2a by the DHCP client 11 via the ISP 2 or the like, requests an available address, and obtains it (step S1). Note that, as described above, such an address is assigned to the fixed host 1 with a usage period of, for example, minutes or days. Subsequently, the fixed host 1 sets the obtained address as the real address of the fixed host 1 by the DHCP client 11 (step S2).
[0034]
Next, the fixed host 1 determines whether the acquisition of the real address is the first acquisition by the IP tunnel processing unit 12 (step S3). If it is the first acquisition (step S3: Y), the fixed host 1 sends the acquired real address (here, the IP address [TTT]) to the ISP 2 and the Internet by the IP tunnel processing unit 12, as shown in FIG. 5 (step S5). Thereby, an IP tunnel between the fixed host 1 and the packet relay device 3 is configured.
[0035]
Next, the fixed host 1 uses the DHCP client 11 to determine whether or not the expiration date of the IP address set as the real address is about to elapse (step S6). Step S6: Y), returning to step S1, the DHCP client 11 requests a new available address from the DHCP server 2a via the ISP 2 or the like and acquires it.
[0036]
Then, the new address acquired by the DHCP client 11 is reset as the real address of the fixed host 1 (step S2), it is determined in step S3 that it is not the first acquisition (step S3: N), and the process proceeds to step S4.
[0037]
In step S4, the fixed host 1 determines whether or not the newly acquired real address has changed from the already acquired real address by the IP tunnel processing unit 12, and if the address has changed. (Step S4: Y), the IP tunnel processing unit 12 notifies (transmits) the new real address to the packet relay device 3 via the ISP 2 and the Internet 5 (step S5). As a result, the IP tunnel between the fixed host 1 and the packet relay device 3 is reconfigured. In this way, the above processing is repeatedly executed, and each time the newly acquired real address changes from the already acquired real address, the fixed host 1 notifies the packet relay device 3 of the real address.
[0038]
On the other hand, as shown in FIG. 2B, the packet relay device 3 receives the real address notified from the fixed host 1 (step S8), and stores it as an IP address of the fixed host 1 on the Internet 5 in the storage unit or the like. Is registered or updated (step S9). That is, the packet relay device 3 updates the registered real address to a new real address every time a notification of a new real address is received. Thus, each time the fixed host 1 notifies the packet relay device 3 of the real address, the IP tunnel is reconfigured.
[0039]
Next, an operation when packet communication is performed after the IP tunnel is configured in the first embodiment will be described.
[0040]
First, a case where an IP packet is sent from the external host 4 to the fixed host 1 via the packet relay device 3 will be described with reference to FIGS.
[0041]
FIG. 4A is a flowchart illustrating a process of the packet relay device 3 that has received an IP packet from the external host 4 in the first embodiment. FIG. 4B is a flowchart illustrating the process of the first embodiment. FIG. 5 is a flowchart showing a process of the fixed host 1 which has received the IP packet from the packet relay device 3. FIG. 5 shows the flow of the IP packet from the external host 4 to the fixed host 1 in the first embodiment, and its change. FIG. FIG. 6 is a diagram showing a flow of an IP packet from the external host 4 to the fixed host 1 and a change when the real address of the fixed host 1 changes in the first embodiment.
[0042]
As shown in FIG. 5, it is assumed that the IP address assigned from the DHCP server 2a has already been set as the real address [TTT] in the fixed host 1, and the packet relay device 3 and the external host 4 Have an IP address [SSS] and an IP address [XXX], respectively. Further, a unique address corresponding to the application unit 13 in the fixed host 1 is an IP address [YYY]. Note that these IP addresses are all global addresses.
[0043]
After establishing a communication session with the application unit 13 of the fixed host 1 via the Internet 5, the application unit 41 of the external host 4 packetizes predetermined data and sends the application data as a destination to those original IP packets. 13 and a header having the IP address [XXX] of the external host 4 as a transmission source as a transmission source, and sends the packet to the Internet 5.
[0044]
Next, in the processing of FIG. 4A, the packet relay device 3 receives the original IP packet transmitted from the external host 4 onto the Internet 5 (Step S11). The original IP packet is routed by a router or the like on the Internet 5 and always passes through the packet relay device 3.
[0045]
Next, the packet relay device 3 causes the IP tunnel management unit 31 to further add the real address [TTT] of the fixed host 1 as the destination and the transmission source to the received original IP packet as shown in FIG. Then, a header having the IP address [SSS] of the packet relay device 3 is added and encapsulated (step S12), and transmitted to the fixed host 1 to the Internet 5 (step S13).
[0046]
On the other hand, in the processing of FIG. 4B, the fixed host 1 receives the IP packet transmitted from the packet relay device 3 via the ISP 2 (Step S21). Then, the original IP packet is extracted from the received IP packet by the IP tunnel processing unit 12 (step S22). The extracted original IP packet is passed (transmitted) to the application unit 13 (step S23).
[0047]
By the way, as shown in FIG. 6, when [UUU] is reacquired as the real address during the continuation of the communication session and changes from the already acquired real address [TTT], the fixed host 1 The process of (A) is executed to notify the packet relay device 3 of a new real address [UUU]. In response, the packet relay device 3 executes the process of FIG. 2B and updates the registered real address [TTT] to a new real address [UUU]. As a result, as shown in FIG. 6, the packet relay device 3 responds to the original IP packet received from the external host 4 with the real address [UUU] of the fixed host 1 as the destination and the packet relay device 3 as the source. The header having the IP address [SSS] is added and encapsulated, and the packet is transmitted to the fixed host 1 to the Internet 5.
[0048]
Next, a case where an IP packet is sent from the fixed host 1 to the external host 4 via the packet relay device 3 will be described with reference to FIGS.
[0049]
FIG. 7A is a flowchart illustrating processing of the fixed host 1 that sends out an IP packet in the first embodiment, and FIG. 7B is a packet relay device that receives an IP packet from the fixed host 1. 8 is a diagram showing a flow of an IP packet from the fixed host 1 to the external host 4 and a change thereof in the first embodiment.
[0050]
First, for example, in response to a request from the external host 4, the application unit 13 packetizes predetermined data (for example, audio and video data, etc.), and sets the IP address of the external host 4 as a destination for those original IP packets. A header having an address [XXX] and a unique address [YYY] corresponding to the application unit 13 as a transmission source is added and output to the IP tunnel processing unit 12 (second and third embodiments described later). But the same).
[0051]
Thus, in the processing of FIG. 7A, the IP tunnel processing unit 12 of the fixed host 1 receives the original IP packet transmitted from the application unit 13 (Step S31). As shown in FIG. 8, the received original IP packet is encapsulated in the IP tunnel processing unit 12, that is, the IP address [SSS] of the packet relay device 3 as a destination for the original IP packet, and A header having the real address [TTT] of the fixed host 1 as a transmission source is added (step S32), and sent to the Internet 5 via the ISP 2 or the like (step S33).
[0052]
On the other hand, in the process of FIG. 7B, the packet relay device 3 receives an IP packet transmitted from the fixed host 1 onto the Internet 5 (Step S41). Then, as shown in FIG. 8, the packet relay device 3 causes the IP tunnel management unit 31 to extract the original IP packet from the received IP packet (Step S42), and forwards the original IP packet to the Internet 5 for the external host 4. It is sent (step S43).
[0053]
Thus, the application unit 41 of the external host 4 receives the original IP packet from the application unit 13 on the fixed host 1.
[0054]
As described above, in the first embodiment, since the IP tunnel is formed or reconfigured between the fixed host 1 and the packet relay device 3, the real address assigned to the fixed host 1 changes during the continuation of the communication session. Even in this case, the communication session can be maintained via the packet relay device 3 using the unique address corresponding to the application unit 13 which does not change when viewed from the external host 4.
[0055]
In the first embodiment, as an example, the configuration in which the application unit 13 and the IP tunnel processing unit 12 are provided in the fixed host 1 has been described. However, FIG. 9 shows a modification of the first embodiment. Such a configuration may be adopted.
[0056]
FIG. 9 is a diagram illustrating a schematic configuration example of a network system SX2 according to a modified example of the first embodiment. In the example shown in FIG. 9, instead of the fixed host 1 shown in FIG. 1, a gateway device (an example of a non-mobile communication device) 1b having a DHCP client 11 and an IP tunnel processing unit 12, and a LAN or the like And a fixed host 1 a having an application unit 13 for realizing the use of various resources from the external host 4. The gateway device 1b is connected to the Internet 5 via the ISP 2, and the functions of the DHCP client 11 and the IP tunnel processing unit 12 provided therein are the same as those of the DHCP client in the fixed host 1 described above. 11 and the function of the IP tunnel processing unit 12. The function of the application unit 13 in the fixed host 1a is the same as the function of the application unit 13 in the fixed host 1 described above. The processing in FIGS. 2, 4 and 7 can be similarly applied to this modified example, and among them, all or a part of the processing of the fixed host 1 is executed by the gateway device 1b.
[0057]
(Second embodiment)
In the first embodiment, the case where the unique address corresponding to the application unit 13 is a global address has been described. However, in the second embodiment, the unique address is a private address that cannot be directly accessed from the Internet 5. The case will be described. Note that, in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.
[0058]
FIG. 10 is a diagram illustrating a schematic configuration example of a network system SX3 according to the second embodiment. In the example of FIG. 10, the external host 4 also has the IP tunnel processing unit 42, and an IP tunnel is configured between the external host 4 and the packet relay device 3. The processing in the IP tunnel management unit 31 of the relay device 3 is partially different from that of the first embodiment.
[0059]
In the second embodiment, an operation when packet communication is performed after an IP tunnel is configured will be described. The processing when the IP tunnel is configured or reconfigured is the same as the processing shown in FIG. 2 of the first embodiment.
[0060]
First, a case where an IP packet is sent from the external host 4 to the fixed host 1 via the packet relay device 3 will be described with reference to FIGS.
[0061]
FIG. 11 is a flowchart showing a process of the packet relay device 3 which has received an IP packet from the external host 4 in the second embodiment. FIG. FIG. 3 is a diagram showing a flow of an IP packet to No. 1 and changes thereof.
[0062]
As shown in FIG. 10, it is assumed that the IP address assigned from the DHCP server 2a has already been set as the real address [TTT] in the fixed host 1, and the packet relay device 3 and the external host 4 Have an IP address [SSS] and an IP address (real address for accessing the Internet 5) [XXX], respectively, and assume that these IP addresses are global addresses.
[0063]
Further, a unique address corresponding to the application unit 13 in the fixed host 1 is an IP address [yyy], a unique address corresponding to the application unit 41 in the external host 4 is an IP address [zzz], and these IP addresses are private addresses. And
[0064]
After establishing a communication session with the application unit 13 of the fixed host 1 via the Internet 5, the application unit 41 of the external host 4 packetizes predetermined data, and sets the fixed host as a destination for those original IP packets. 1, a header having a unique address [yyy] corresponding to the application unit 13 and a unique address [zzz] corresponding to the application unit 41 operating on the external host 4 as a transmission source is added. Further, the IP tunnel processing unit 42 of the external host 4 sends a header having the IP address [SSS] of the packet relay device 3 as the destination and the real address [XXX] of the external host 4 as the source for the original IP packet. The data is encapsulated by being added, and transmitted on the Internet 5 as shown in FIG.
[0065]
Next, in the processing of FIG. 11, the packet relay device 3 receives an IP packet transmitted from the external host 4 onto the Internet 5 (Step S51). Then, as shown in FIG. 12, the packet relay device 3 extracts the original IP packet from the received IP packet (step S52), and with respect to the original IP packet, the real address [TTT] of the fixed host 1 as the destination. Then, a header having the IP address [SSS] of the packet relay device 3 as a transmission source is added and encapsulated (Step S53), and the packet is transmitted to the fixed host 1 to the Internet 5 (Step S54).
[0066]
On the other hand, the processing of the fixed host 1 is the same as the processing of FIG. 4B described in the first embodiment. That is, the fixed host 1 receives the IP packet transmitted from the packet relay device 3 (Step S21), and extracts an original IP packet therefrom (Step S22). The extracted original IP packet is passed to the application unit 13 on the fixed host 1 (Step S23).
[0067]
Further, the processing of the fixed host 1 and the packet relay device 3 when the real address [UUU] is reacquired during the continuation of the communication session and changes from the already acquired real address [TTT] is the same as in the first embodiment. The same is true.
[0068]
Next, a case where an IP packet is sent from the fixed host 1 to the external host 4 via the packet relay device 3 will be described with reference to FIG.
[0069]
FIG. 13 is a flowchart showing the processing of the packet relay device 3 that has received an IP packet from the fixed host 1.
[0070]
Note that the processing of the fixed host 1 in this case is the same as the processing of FIG. 7A described in the first embodiment, and a description thereof will be omitted.
[0071]
In the process of FIG. 13, the packet relay device 3 receives an IP packet transmitted from the fixed host 1 onto the Internet 5 (Step S61). Then, the packet relay device 3 extracts the original IP packet from the received IP packet (step S62), and with respect to the original IP packet, the real address [XXX] of the external host 4 as the destination and the packet relay as the source. A header having the IP address [SSS] of the device 3 is added and encapsulated (step S63), and the packet is sent to the external host 4 to the Internet 5 (step S64).
[0072]
Thus, the IP tunnel processing unit 42 of the external host 4 receives the IP packet from the packet relay device 3, extracts the original IP packet from the application unit 13 on the fixed host 1, and operates on the external host 4. To the application section 41 that is in operation.
[0073]
As described above, in the second embodiment, when the unique address corresponding to the application unit 13 in the fixed host 1 is a private address, the communication between the fixed host 1 and the packet relay device 3 and the packet relay device 3 Since an IP tunnel is configured between the external host 4 and the external host 4, even if the real address assigned to the fixed host 1 changes during the continuation of the communication session, the packet is relayed by the unique address which does not change when viewed from the external host 4. A communication session can be maintained via the device 3. Further, in the second embodiment, even when a global address cannot be used as the unique address (the number of available global addresses is limited in the IPv4 Internet), the communication session is disconnected and communication cannot be continued. Can be prevented.
[0074]
In the second embodiment, the modification of the first embodiment is applied, and instead of the fixed host 1, a gateway device 1b having a DHCP client 11 and an IP tunnel processing unit 12 is connected to the gateway device 1b by a LAN or the like. The external host 4 may be configured to include a fixed host 1a having an application unit 13 for realizing resources to be used.
[0075]
(Third embodiment)
In the third embodiment, as in the second embodiment, a case where the unique address corresponding to the application unit 13 is a private address that cannot be directly accessed from the Internet 5 will be described. Note that, in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.
[0076]
FIG. 14 is a diagram illustrating a schematic configuration example of a network system SX4 according to the third embodiment. In the example of FIG. 14, the packet relay device 3 has a function of a well-known NAT unit (address translation device) 32 as an address translation unit of the present application. The difference from the second embodiment is that an IP tunnel is not configured.
[0077]
The NAT unit 32 prepares a global address (alternate global address) associated with a unique address that is a private address for using the application unit 13, and the external host 4 or the like uses the alternative global address. , The application section 13 can be used via the Internet 5.
[0078]
Next, an operation when packet communication is performed after an IP tunnel is configured in the third embodiment will be described. The processing when the IP tunnel is configured or reconfigured is the same as the processing shown in FIG. 2 of the first embodiment.
[0079]
First, a case where an IP packet is sent from the external host 4 to the fixed host 1 via the packet relay device 3 will be described with reference to FIGS.
[0080]
FIG. 15 is a flowchart showing a process of the packet relay device 3 which has received an IP packet from the external host 4 in the third embodiment, and FIG. FIG. 3 is a diagram showing a flow of an IP packet to No. 1 and changes thereof.
[0081]
As shown in FIG. 14, it is assumed that the IP address assigned from the DHCP server 2a has already been set as the real address [TTT] in the fixed host 1, and the packet relay device 3 and the external host 4 Have an IP address [SSS] and an IP address [XXX], respectively, and assume that these IP addresses are global addresses.
[0082]
Further, a unique address (private address) corresponding to the application unit 13 in the fixed host 1 is defined as an IP address [yyy]. Further, the global address reserved for the application unit 41 on the external host 4 to communicate with the application unit 13 on the fixed host 1 is defined as an IP address [UUU]. Since this IP address [UUU] is a valuable global address in IPv4, even if the IP address [UUU] is operated and managed so that it is occupied only while the communication session between the application unit 41 of the external host 4 and the application unit 13 of the fixed host 1 continues. Good.
[0083]
The application unit 41 of the external host 4 packetizes predetermined data after establishing a communication session with the application unit 13 of the fixed host 1 via the Internet 5 and fixes them as destinations for those original IP packets. A header having the IP address [UUU] reserved for communication with the host 1 and the IP address [XXX] of the external host 4 as a transmission source is added, and the packet is transmitted to the Internet 5 as shown in FIG.
[0084]
Next, in the process of FIG. 15, the packet relay device 3 receives the original IP packet transmitted from the external host 4 onto the Internet 5 (Step S71). Then, as shown in FIG. 16, the packet relay device 3 uses the NAT unit 32 to change the destination IP address [UUU] (global address) in the header added to the received original IP packet into the application unit 13 of the fixed host 1. Is converted to a unique address [yyy] (private address) (step S72), which is passed to the IP tunnel management unit 31. Then, the packet relay device 3 further adds the real address [TTT] of the fixed host 1 as the destination and the packet relay device as the source to the original IP packet whose IP address has been converted by the IP tunnel management unit 31. A header having the IP address [SSS] of No. 3 is added and encapsulated (step S73), and sent to the fixed host 1 to the Internet 5 (step S74).
[0085]
On the other hand, the processing of the fixed host 1 is the same as the processing of FIG. 4B described in the first and second embodiments, and a description thereof will be omitted. Also, the processing of the fixed host 1 and the packet relay device 3 when the real address [UUU] is reacquired during the continuation of the communication session and changes from the already acquired real address [TTT] is the same as that of the first embodiment. The same is true.
[0086]
Next, a case where an IP packet is sent from the fixed host 1 to the external host 4 via the packet relay device 3 will be described with reference to FIG.
[0087]
FIG. 17 is a flowchart showing the processing of the packet relay device 3 that has received an IP packet from the fixed host 1.
[0088]
Note that the processing of the fixed host 1 in this case is the same as the processing of FIG. 7A described in the first and second embodiments, and a description thereof will be omitted.
[0089]
In the process of FIG. 17, the packet relay device 3 receives an IP packet transmitted from the fixed host 1 onto the Internet 5 (Step S81). Then, the packet relay device 3 causes the IP tunnel management unit 31 to extract the original IP packet from the received IP packet (step S82) and passes it to the NAT unit 32. Then, the packet relay device 3 uses the NAT unit 32 to change the unique address [yyy] (private address) corresponding to the application unit 13 in the fixed host 1 of the transmission source in the header added to the original IP packet into the IP address [UUU (Global address) (step S83), and sends the original IP packet to the Internet 5 toward the external host 4 (step S84).
[0090]
Thus, the application unit 41 of the external host 4 receives the original IP packet from the application unit 13 on the fixed host 1.
[0091]
As described above, in the third embodiment, when the unique address corresponding to the application unit 13 in the fixed host 1 is a private address, an IP tunnel is configured between the fixed host 1 and the packet relay device 3. Further, since the packet relay device 3 has the NAT unit 32, even when the real address assigned to the fixed host 1 changes during the continuation of the communication session, the packet relay device 3 uses the IP address [UUU] which does not change when viewed from the external host 4. A communication session can be maintained via the NAT unit 32 of the packet relay device 3. Further, in the third embodiment, even when a global address cannot be used as a unique address of a resource in the fixed host 1 (the number of available global addresses is limited in the IPv4 Internet), the communication session is disconnected and communication is stopped. It is possible to prevent the user from being unable to continue.
[0092]
Also in the third embodiment, the modification of the first embodiment is applied, and instead of the fixed host 1, a gateway device 1b having a DHCP client 11 and an IP tunnel processing unit 12 is connected to the gateway device 1b by a LAN or the like. The external host 4 may be configured to include a fixed host 1a having an application unit 13 for realizing resources to be used.
[0093]
As described above, according to the above embodiment, the fixed host 1 acquires the real address, notifies the packet relay device 3 of the real address via the Internet 5, and the packet relay device 3 Is registered as an IP address of the fixed host 1 on the Internet 5, and the fixed host 1 sets a new address before the expiration date of the real address elapses. Obtains the real address, determines whether the real address has changed from the already obtained real address, and, if the real address has changed, transmits the newly obtained real address to the packet relay device. 3, the packet relay device 3 updates the already registered real address to the newly obtained real address notified from the fixed host 1. Therefore, an IP tunnel is configured or reconfigured between the fixed host 1 and the packet relay device 3, and even if the real address assigned to the fixed host 1 changes during the continuation of the communication session, the external host 4 The communication session can be maintained via the packet relay device 3 by using a unique address that does not change from the viewpoint of the user or a global address associated with the unique address. Therefore, the communication operation can be continued even when, for example, receiving a video / audio stream or performing mutual communication, or transferring a large-capacity file that requires a long time to transfer.
[0094]
Note that the above-described embodiment may be configured by applying a known mobile IP technology (a series of technologies such as RFC2002, which are studied by the IETF). In the mobile IP technology, a mobile node (MN: Mobile Node) having a permanently assigned home address and a home agent (HA) which is a router having an interface on a home link of the MN (a link where the MN should exist). : Home Agent) Depending on the configuration, an external agent (FA: Foreign Agent) for assisting detection of link movement of the MN and formation of an IP tunnel is provided. When the connection point of the MN to the Internet is changed from the home link to another external link, the FA or the MN notifies the HA of the transfer destination IP address (care-of address) on the new external link of the moving destination. The care-of address is registered. As a result, an IP tunnel is formed between the HA and the care-of address of the movement destination, and the HA captures an IP packet addressed to the home address of the MN from an external host and transfers the packet to the care-of address of the MN via the IP tunnel. The MN can move the link while maintaining the communication session.
[0095]
As described above, the mobile IP technology is based on the premise that the MN moves over a plurality of links, but this technology is applied to a non-mobile communication device. For example, the IP tunnel processing unit 12 in the fixed host 1 operates as an MN in the mobile IP technology, and the IP tunnel management unit 31 in the packet relay device 3 operates as an HA in the mobile IP technology. Whenever the real address (corresponding to the coexistence care-of address in the configuration where no FA exists) changes, the HA of the packet relay device 3 is notified of the real address, and the HA is registered in the notified real address. An IP tunnel as described above can be configured or reconfigured. As a result, even when the real address of the fixed host 1 connected to the Internet 5 changes during the continuation of the communication session, the fixed address is associated with the unique address which is the same IP address as seen from the external host 4 or the unique address. Communication can be continued with the global address, that is, a communication session can be maintained. Even when the mobile IP technology is applied as described above, the processes of the fixed host 1 and the packet relay device 3 are the same as those of the first, second, and third embodiments (FIGS. 2, 4 and the like). Processing shown in FIG.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration example of a network system SX1 according to an embodiment.
FIG. 2A is a flowchart showing processing of a fixed host 1 when an IP tunnel is configured or reconfigured, and FIG. 2B is a flowchart showing processing of a packet relay device 3 in that case. .
FIG. 3 is a diagram showing a state in which an IP address is notified from a fixed host 1 to a packet relay device 3;
FIG. 4A is a flowchart illustrating processing of the packet relay device 3 that has received an IP packet from the external host 4 in the first embodiment, and FIG. 4B is a flowchart illustrating processing in the first embodiment; 9 is a flowchart showing a process of the fixed host 1 that has received the IP packet from the packet relay device 3.
FIG. 5 is a diagram showing a flow of an IP packet from an external host 4 to a fixed host 1 and a change thereof in the first embodiment.
FIG. 6 is a diagram showing a flow of an IP packet from the external host 4 to the fixed host 1 and a change when the real address of the fixed host 1 changes in the first embodiment.
FIG. 7A is a flowchart illustrating processing of a fixed host 1 that sends out an IP packet in the first embodiment, and FIG. 7B is a packet relay device that receives an IP packet from the fixed host 1. 6 is a flowchart showing a process of No. 3;
FIG. 8 is a diagram showing a flow of IP packets from a fixed host 1 to an external host 4 and changes thereof in the first embodiment.
FIG. 9 is a diagram illustrating a schematic configuration example of a network system SX2 according to a modification of the first embodiment.
FIG. 10 is a diagram illustrating a schematic configuration example of a network system SX3 according to the second embodiment.
FIG. 11 is a flowchart illustrating a process of the packet relay device 3 that has received an IP packet from the external host 4 in the second embodiment.
FIG. 12 is a diagram showing a flow of an IP packet from an external host 4 to a fixed host 1 and a change thereof in the second embodiment.
FIG. 13 is a flowchart illustrating a process of the packet relay device 3 that has received an IP packet from the fixed host 1.
FIG. 14 is a diagram illustrating a schematic configuration example of a network system SX4 according to the third embodiment.
FIG. 15 is a flowchart illustrating a process of the packet relay device 3 that has received an IP packet from the external host 4 in the third embodiment.
FIG. 16 is a diagram showing a flow of an IP packet from an external host 4 to a fixed host 1 and a change thereof in the third embodiment.
FIG. 17 is a flowchart showing a process of the packet relay device 3 that has received an IP packet from the fixed host 1.
[Explanation of symbols]
1, 1a Fixed host
1b Gateway device
2 ISP
2a DHCP server
3 Packet relay device
4 External host
5 Internet
11 DHCP client
12 IP tunnel processing unit
13 Application section
31 IP Tunnel Management Department
32 NAT section
S network system

Claims (18)

A non-mobile communication device that is connected to a network and performs packet communication with another communication device via a packet relay device,
Address acquisition means for acquiring an address to which the expiration date of the communication device has been given;
Address notification means for notifying the packet relay device of the address via the network,
The address acquisition means acquires a new address before the expiration date of the address elapses,
The address notifying means determines whether or not the newly obtained address has changed from the already obtained address.If the address has changed, the address notifying unit notifies the newly obtained address of the newly obtained address. A communication device for notifying a packet relay device. The communication device according to claim 1,
An original packet to which an address of the other communication device as a destination and a header having a unique address corresponding to a predetermined application operating on the communication device or a device connected to the communication device as a transmission source are added. On the other hand, further, a packet encapsulating means for encapsulating by adding a header having an address of the packet relay device as a destination and an address to which the expiration date of the communication device is given as a transmission source,
And a packet transmitting means for transmitting the encapsulated packet to the network toward the packet relay device. A packet relay device connected to a network and relaying a packet exchanged between the communication device according to claim 2 and another communication device,
A packet relay device, comprising: an address registration unit that registers an address to which an expiration date notified from the communication device is given as an address of the communication device on the network in an updatable manner. The packet relay device according to claim 3,
For the original packet added with a header having the address of the other communication device as a destination and a unique address corresponding to the application as a source, further, the address of the packet relay device as a destination and the source as the source Packet receiving means for receiving an encapsulated packet to which a header having an address with an expiration date has been added;
Packet extraction means for extracting the original packet from the packet;
A packet transmission unit that transmits the original packet to the network toward the other communication device. The packet relay device according to claim 3,
For the original packet to which an address of the other communication device as a destination and a header having a unique address that is a private address corresponding to the application as a transmission source are added, further, the address of the packet relay device as a destination, and Packet receiving means for receiving an encapsulated packet to which a header having an address to which the expiration date is given as a transmission source is added;
Packet extraction means for extracting the original packet from the packet;
Packet encapsulation means for encapsulating the original packet by adding a header having the address of the other communication device as a destination and the address of the packet relay device as a source,
A packet transmitting unit that transmits the encapsulated packet to the network toward the other communication device. The packet relay device according to claim 3,
For the original packet to which an address of the other communication device as a destination and a header having a unique address that is a private address corresponding to the application as a transmission source are added, further, the address of the packet relay device as a destination, and Packet receiving means for receiving an encapsulated packet to which a header having an address to which the expiration date is given as a transmission source is added;
Packet extraction means for extracting the original packet from the packet;
Address translation means for translating the private address of the transmission source in the header added to the original packet to a global address,
A packet transmitting unit that transmits the packet whose address has been converted to the network to the other communication device. The packet relay device according to claim 3,
Packet receiving means for receiving an original packet to which a header having a unique address corresponding to the application as a destination and an address of the other communication device as a transmission source is added;
For the original packet, further, a packet encapsulating means for encapsulating by adding a header having the address to which the expiration date is given as a destination and the address of the packet relay device as a source,
A packet transmitting unit that transmits the encapsulated packet to the network toward the communication device. The packet relay device according to claim 3,
For an original packet to which a header having a unique address that is a private address corresponding to the application as a destination and a unique address that is a private address corresponding to a predetermined application operating on the other communication device as a source is added. Packet receiving means for receiving an encapsulated packet added with a header having an address of a packet relay device as a destination and an address for connection from the network of the other communication device as a transmission source,
Packet extraction means for extracting the original packet from the packet;
Packet encapsulation means for encapsulating the original packet by adding a header having the address to which the expiration date has been given as a destination and the address of the packet relay device as a source,
A packet transmitting unit that transmits the encapsulated packet to the network toward the communication device. The packet relay device according to claim 3,
A global address associated with a unique address that is a private address corresponding to the application as a destination, and an original packet to which a header having the address of the other communication device is added as a source is transmitted from the other communication device to the network. Packet receiving means for receiving via
Address translation means for translating the global address of the destination in the header added to the original packet into a unique address that is a private address corresponding to the application,
Packet encapsulating means for encapsulating the original packet with the translated address further by adding a header having the address with the expiration date as a destination and the address of the packet relay device as a source; ,
A packet transmitting unit that transmits the encapsulated packet to the network toward the communication device. The communication device according to claim 1,
Packet receiving means for receiving a packet transmitted from the packet relay device according to any one of claims 7 to 9,
A packet extracting unit for extracting an original packet from the packet. The communication device according to claim 10,
A communication device for transmitting the original packet or data included in the original packet to the application. A non-mobile communication device that is connected to a network and performs packet communication with another communication device, and a packet relay device that relays a packet exchanged between the communication device and the other communication device, A network system comprising:
The communication device obtains an address to which its own expiration date is given, notifies the packet relay device of the address via the network, and the packet relay device transmits the address notified from the communication device. Registering the communication device as an address on the network,
The communication device obtains a new address before the expiration date of the address elapses, determines whether the address has changed from the already obtained address, and determines whether the address has changed. Notifies the packet relay device of the newly obtained address,
The network system, wherein the packet relay device updates the registered address to the newly acquired address notified from the communication device. A communication method in a non-mobile communication device connected to a network and performing packet communication with another communication device via a packet relay device,
Obtaining an address to which the expiration date of the communication device is given, and notifying the packet relay device of the address via the network,
Before the expiration date of the address, a new address is obtained, and it is determined whether the newly obtained address has changed from the address already obtained, and the address has changed. Notifying the packet relay device of the newly acquired address. A communication method in a packet relay device connected to a network and relaying a packet exchanged between the communication device according to claim 2 and another communication device,
Registering the address given the expiration date notified from the communication device as an address of the communication device on the network,
And updating the registered address to the new address when a new address is notified from the communication device. A non-mobile communication device that is connected to a network and performs packet communication with another communication device, and a packet relay device that relays a packet exchanged between the communication device and the other communication device, A communication method in a network system comprising:
The communication device obtains an address to which its own expiration date is given, and notifying the packet relay device of the address via the network,
The packet relay device, the step of registering the address notified from the communication device as an address of the communication device on the network,
The communication device obtains a new address before the expiration date of the address elapses, determines whether the address has changed from the already obtained address, and determines whether the address has changed. Notifying the packet relay device of the newly obtained address,
The packet relay device updating the registered address with the newly obtained address notified from the communication device. A computer included in a non-mobile communication device that is connected to a network and performs packet communication with another communication device via a packet relay device,
Address acquisition means for acquiring an address to which the expiration date of the communication device has been given;
Address notification means for notifying the packet relay device of the address via the network, and function as,
The address acquisition means acquires a new address before the expiration date of the address elapses,
The address notifying means determines whether or not the newly obtained address has changed from the already obtained address, and if the address has changed, the newly obtained address is A communication processing program having a function of notifying a packet relay device. A computer connected to a network and included in a packet relay device that relays a packet exchanged between the communication device according to claim 2 and another communication device,
Register the address given the expiration date notified from the communication device as the address of the communication device on the network,
Further, when a new address is notified from the communication device, the communication device is operable to update the registered address to the new address. A recording medium characterized by recording the communication processing program according to claim 16 or 17 in a computer-readable manner.

Images