JP2000174824A - Communication system, gateway used for the communication system, radio information terminal and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a radio information terminal to easily cope with changeover of gateways and to reduce the negotiation time required for the changeover by informing the terminal of occurrence of the gateway changeover, informing the terminal about information required for communication with a server via a changeover destination gateway and executing a communication start procedure with the changeover destination gateway. SOLUTION: When information required for communication with a sever 6 via a changeover destination gateways 5, (4) is given to the radio information terminal, a restart means for the terminal 1 interrupts communication through a changeover source gateways 4, (5) and executes a communication restart procedure to the changeover destination gateways 5, (4). In the case of switching the changeover source gateways 4, (5), the changeover source gateways 4, (5) starts communication with the changeover destination gateways 5, (4) by an information exchange means to allow the changeover destination gateways 5, (4) to confirm the information required for the communication in advance. The changeover source gateways 4, (5) can inform the changeover destination gateways 5, (4) about the address and the capability of the radio information terminal 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly to a method for switching a gateway in a wireless communication system, and a gateway used in the method.
The present invention relates to a wireless information terminal and a communication system.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of so-called Internet services such as WWW (World Wide Web), the scale of computer networks has been expanded and connection forms have been diversified.

[0003] In accordance with this, gateways for connecting information terminals, servers and the like to networks are also required to have improved processing capability and increased functions.

As an example of the diversification of connection forms, a wireless network that can be used while moving or in a place where it cannot be directly connected to a computer network by using a mobile communication network such as a mobile phone network by adding wireless communication capability to an information terminal. ,
So-called mobile computing can be mentioned.
FIG. 5 and FIG. 6 are conceptual diagrams showing a communication mode using the wireless network.

FIG. 5 shows the configuration of a wireless network using a public network or a private network.

When a user wants to execute an application possessed by the terminal 1, the terminal 1 is connected to the server 6 via the radio base station 2, the network 3 and the gateway 11 or the gateway 12, and communicates with the server. To run the application.

FIG. 6 shows a form of a wireless network in which the gateway itself has a server function and does not pass through a network operated in a narrower range than in FIG. 5, for example, in an office.
That is, the terminal 1 communicates with the gateway 11 or the gateway 12 via the wireless base station 2 to execute an application.

In the above-mentioned wireless network, the function of the gateway is added in accordance with the change of the network,
It is necessary to temporarily stop the operation of the gateway for periodic maintenance and the like. In order to continue network operation even when the gateway stops,
As shown in FIGS. 5 and 6, a gateway connection switching function is provided in which a plurality of gateways are prepared and, for example, when one of the gateways 11 stops, the terminal and the server can communicate via the other gateway 12. Is required for the network.

Here, an outline of the communication protocol between the terminal and the gateway will be described with reference to FIG.

The application 71 on the terminal side is, for example,
A program directly operated by the user, such as a WWW browser, and a gateway-side application 75 (here, a server function is built in the gateway as shown in FIG. 6).
Is a program for exchanging information with a terminal-side application, such as WWW server software, for example.

The session layer protocol means 72 is a protocol for providing a common transfer control function to various applications 71 and 75, for example, means for delimiting transfer data and performing a transfer process in units of delimiters.
The session layer management entity 73 manages system resources (for example, memory) used by a plurality of session processes and the like generated by data communication between the terminal and the server, and manages processing (for example, notification of gateway switching timing) over the entire system. It is a program. Further, the lower protocol 74 is a program and a device for performing communication control.

FIG. 8 shows a communication sequence of the communication mode of FIG.

The session layer protocol means 80 of the terminal 1
2 is communicating with session layer protocol means 804 of gateway 11 to execute application 801
03. At this time, when a gateway switching instruction 808 is issued from the operator to the management entity 805 of the gateway 11, a disconnection notification 809 is issued to the session layer protocol unit 802 of the terminal 1 via the management entity 805 and the session layer protocol unit 804. I do. As a result, the session layer protocol unit 802 of the terminal 1
The application 801 suspends the execution without displaying the disconnection display 810 or not.

When the gateway 11 issues the disconnection notification 809, the gateway 11 is stopped by the operation of the operator or the function of the gateway 11. After that, the terminal 1 re-executes the interrupted application 801 by using information stored in the terminal 1 itself.
2 to the session layer protocol means 802.
Request to.

After a session 812 is established between the session layer protocol means 802 and the session layer protocol means 806 of the gateway 12, the communication becomes 813 during communication, and the interrupted application 801 can be re-executed.

[0016]

In the prior art described above, when performing gateway connection switching by stopping the gateway, the terminal temporarily terminates the running application, reconnects to another gateway, and then executes the application. Has to be re-executed from the beginning.

In order for the terminal to re-execute the application after changing the gateway as described above, it is necessary to store in advance the address information of a plurality of gateways to be changed in the terminal. The use of redundant resources, in which information necessary only for switching connections is always stored in the terminal, is a problem for terminals that require small and multifunctional.

There is also a problem that every time the network configuration changes such as addition or deletion of a server or a gateway, the address information of the gateway of the terminal must be updated. In addition, when switching the connection to another gateway, it is necessary to negotiate information such as the port number, address, and capabilities of the terminal between the terminal and the switching destination gateway. Another problem is that the time required to re-execute is longer.

Further, as a result of the negotiation between the terminal and the switching destination gateway, if the gateway does not have the capability or resources to accommodate the communication capability (capability) of the terminal, the connection with the gateway is terminated, and the capability of the terminal is terminated. There is also a problem that a situation in which the work efficiency is extremely low in which connection to another gateway is attempted until a gateway capable of accommodating the same is found.

The present invention has been made in order to solve and improve the above-mentioned problems. The present invention changes the connection destination gateway without terminating the application execution on the terminal, and the terminal always retains information on a plurality of gateways. There is no need for the terminal to easily respond to changes in the network configuration, shorten the negotiation time for connection between the terminal and the gateway, and connect to a gateway that has the capacity and resources to accommodate the terminal at one time. It is an object of the present invention to provide a gateway dynamic switching method and apparatus that enables the method.

[0021]

In order to achieve the above object, the present invention employs the following constitution.

First, the present invention relates to a communication system for establishing communication between a wireless information terminal and a server via a gateway. In the communication system, it is necessary to switch a gateway that should be used for some reason to another gateway. Is applied when an error occurs.

[0023] First, the present invention is, when there is a switching instruction of the gateway, the generation of the gateway switching information notifying means adapted to you notify the radio information terminal.

In the above information, when only the switching of the gateway is notified, in addition to the switching, information necessary for the wireless information terminal to communicate with the server via the gateway of the switching destination, for example, the gateway of the switching destination Address can be included.

When information necessary for communicating with the server is notified to the terminal via the switching destination gateway, the restarting means of the wireless information terminal interrupts communication with the switching source gateway and performs switching. Perform the procedure to resume communication with the previous gateway. Incidentally, when the wireless information terminal is not receiving the service from the server, there is a case where the switching source receives the switching notification from the gateway. At this time, the communication activation unit of the wireless information terminal activates communication with the server via the switching destination gateway.

When switching the gateway, the switching source gateway may notify the switching destination gateway in advance of information necessary for communication with the wireless information terminal by the information exchange means and start communication from the switching destination gateway. You can keep a confirmation to that effect.

When information exchange means is provided between the gateways, the capability can be notified from the switching source gateway to the switching destination gateway together with the address of the wireless information terminal. As a result, the switching destination gateway notifies the switching source gateway of the upper limit of its own capability when its own capability is inferior.

The switching source gateway notifies the wireless information terminal of the upper limit capability, and the wireless information terminal resumes communication via the switching destination gateway with the upper limit capability. However, when communication is not possible with the upper limit capability, the judgment means of the switching source,
Alternatively, the communication is stopped by the determination means of the wireless information terminal.

An incomplete transaction at the time of the above interruption processing may remain.

When the information exchange means is not provided, the switching source gateway notifies the server corresponding to the switching destination gateway of the address of the response destination (wireless information terminal) before the restart of the wireless information terminal. Thus, at the time of resumption, the above-mentioned uncompleted transaction can be completed. When the information exchange means is provided, the incomplete transaction can be completed at the time of resumption by notifying the switching gateway of the transaction status to the switching destination gateway.

Before and after the information exchange, the communication state between the wireless information terminal and the server may change. In this case, the latest communication state is notified to the switching destination gateway in the restart procedure.

Here, the terms described above are as follows in the following description and drawings.

Information notifying means: The switching instruction is issued from the gateway operator to the switching source gateway. In response to the instruction, the management entity of the switching source gateway edits the notification content to the wireless information terminal, and notifies the terminal to that effect via the session layer protocol. Therefore, the information notifying means is constituted by the management entity of the gateway and the session layer protocol.

Information exchange means: Both the switching source gateway and the switching destination gateway are provided, and execute information exchange such as the address of the wireless information terminal between both management entities. Since the editing of the contents of the notification is naturally executed by the management entity, the information exchange means is also constituted by the management entity. Although information is exchanged between management entities in the drawing, information exchange may be performed from the management entity via a session layer protocol.

Resume start-up means: The session layer protocol of the wireless information terminal receives information such as the address of the switching destination gateway, performs an interruption process with the switching source gateway, and then executes a restarting procedure. Therefore, the restart activation means is constituted by the session layer protocol.
Note that the point that the communication activation means does not perform the interruption processing is as follows.
Although different from the above-mentioned restart activation means, this case is also constituted by a session layer protocol.

Judging means: As described above, the capability of the wireless information terminal is compared with the capability of the switching destination gateway to determine whether communication between the wireless information terminal and the switching destination gateway is possible. There is a case where it is provided in the wireless information terminal and a case where it is provided in the switching source gateway. In either case, the management entity will make the decision.

[0037]

Embodiments of the present invention will be described below.

(Embodiment 1) FIG. 1 shows a configuration of a wireless network via a public network of a gateway sharing a server according to an embodiment of the present invention.

A wireless information terminal (hereinafter simply referred to as a terminal) 1 is a wireless information terminal such as a notebook PC to which a mobile phone is connected, a base station 2 is a mobile phone base station, for example, and a network 3 Is, for example, a public telephone network.

The gateways 4 and 5 share the server 6, and connect the network 3 and the server 6. The gateways 4 and 5 have information exchange means for performing negotiation between gateways according to the present invention. This information exchange means includes, for example, a wired or wireless connection means 13 which enables direct communication between the gateways 4 and 5, or a connection between the gateways 4 and 5 and the server 6 via the connection means 14 or the network 3. May be used.

The terminal 1 is connected to the server 6 via the base station 2, the network 3, and the gateway 4 or 5,
The application is executed using the information 7 of the server 6.

FIG. 9 shows a sequence when the gateway 4 is stopped while the terminal 1 is connected to the server 6 via the gateway 4 and the gateway 4 is switched to the gateway 5.

Session layer protocol means 90 of terminal 1
2 communicates with the application 911 of the server 6 via the gateway 4 to execute the application 901.

At this time, the communication protocol used in the communication 903 between the session layer protocol unit 902 of the terminal 1 and the session layer protocol unit 904 of the gateway 4 and the session layer protocol unit 904 of the gateway 4
Since the communication protocol used in communication 907 between the server 4 and the server 6 is different, the protocol conversion means 9 of the gateway 4
At 05, protocol conversion is performed. That is, the communication 90
The communication protocol used in 3 is converted into the communication protocol used in the communication 907 between the gateway 4 and the server 6 by the above-mentioned protocol conversion means 905, thereby enabling communication between the terminal 1 and the server 6.

However, depending on the application, there is a case where protocol conversion is not required. In this case, the protocol conversion at the gateway is not performed.

Here, when the server switching instruction 912 is issued from the operator while the terminal 1 and the server 6 are communicating, the management entity 906 of the gateway 4 transmits the communication of the terminal 1 from the gateway 4 to the gateway 5. Negotiation with the management entity 910 of the gateway 5 is performed to switch to.

That is, the management entity 906 of the gateway 4 notifies the management entity 910 of the gateway 5 of the session switching request 913. At this time, the selection of the switching destination gateway (in this case, the gateway 5) to which the gateway 4 notifies the session switching request is performed based on information of another gateway stored in advance by the gateway 4 or specified by an operator. Is also possible. At the same time as the session switching request 913, information such as the address of the currently connected terminal, the session ID, the maximum data length, and the window size is notified to the management entity 910 of the gateway 5.

The management entity 910 of the gateway 5 transmits the information received in response to the session switching request 913 to the session layer protocol 908.
When the content of the information received by the session layer protocol unit 908 is confirmed, the session can be switched, and the management entity 910 of the gateway 5 notifies the management entity 906 of the gateway 4 of the session switching confirmation 914.

Upon receiving the session switching confirmation 914, the management entity 906 of the gateway 4 notifies the session layer protocol unit 904 of a switching instruction 922. The session layer protocol unit 904 that has received the switching instruction 922 notifies the switching destination gateway address to the session layer protocol unit 902 of the terminal 1 together with the switching notification 915.

Thus, the terminal 1 knows the address information of the gateway 5 which is the switching destination gateway by the switching notification 915.

The session layer protocol means 90 of the terminal 1
When the switching notification 915 is received together with the address information, when the application 901 being executed is not communicating with the application 911 of the server 6, the interruption 2 is interrupted at a timing convenient for interrupting the session.
16 to the session layer protocol means 9 of the gateway 4
04 is notified.

The session layer protocol means 904 of the gateway 4 notifies the management entity 906 of the reception of the interruption 916, and
06 is an interruption instruction 9 to the session layer protocol means 904.
23 is notified. Accordingly, the session layer protocol unit 904 notifies the session layer protocol unit 902 of the terminal 1 of the interruption confirmation 917, and thereafter, the terminal 1
Session is interrupted.

However, after reporting the interruption 916 to the session layer protocol means 904 of the gateway 4, the terminal 1
The server connection switching sequence can be continued regardless of the state of the gateway 4.

Therefore, the procedure of the interruption instruction 923 and the interruption confirmation 917 may be omitted, or the session layer protocol unit 904 autonomously transmits the interruption confirmation 917 to the session layer protocol unit 902 of the terminal 1 without the interruption instruction 923.
May be notified. Further, depending on the type of the gateway 4, only the interruption instruction 923 may be issued and the interruption confirmation 917 may not be made. In any case, if there is no interruption confirmation 917, the session of the terminal 1 is interrupted after notifying the interruption 916.

Further, when the session layer protocol unit 902 of the terminal 1 receives the switching notification 915, it instructs the application 901 to perform a switching display of the gateway. Session layer protocol means 9
02 may notify the session layer protocol means 904 of the gateway 4 of the interruption 916.

After that, the session layer protocol unit 902 of the terminal 1 transmits to the session layer protocol unit 908 of the gateway 5 a restart 91 including information such as the address of the terminal.
8 is notified. Here, the session layer protocol unit 908 of the gateway 5 transmits the session switching request 913 with the gateway 4 and the session switching confirmation 914 described above.
Therefore, when the terminal 1 receives the restart 918 from the session layer protocol unit 902 of the terminal 1 as described above, the terminal 1 is immediately notified of the restart confirmation 919.

By the restart confirmation 919 from the session layer protocol means 908 of the gateway 5, the suspended session of the terminal 1 is immediately restarted.
The session layer protocol unit 902 of the terminal 1 establishes communications 920 and 921 with the application 911 of the server 6 via the protocol conversion unit 909 of the gateway 5 to execute the application 901.

FIG. 18 is a sequence diagram showing a case where a disconnection is used instead of the interruption and a disconnection is used instead of the restart.

The switching notification 1915 in FIG.
The sequence corresponds to the switching notification 915, and the procedure up to that point is the same sequence in both figures, so that the description is omitted. Thereafter, the session layer protocol unit 1902 of the terminal 1 notifies the disconnection 1916 to disconnect the session.

Next, based on the switching destination gateway address notified to the terminal 1 together with the switching notification 1915, the session layer protocol unit 1902 of the terminal 1
Is the session layer protocol means 19 of the gateway 5
08 is notified of the connection 1918. The session protocol 1908 of the gateway 5 processes as a new session, and the session layer protocol 19 of the gateway 5
08 is the session layer protocol unit 1908 of the terminal 1
, A connection confirmation 1919 is notified. As a result, the session layer protocol unit 1902 of the terminal 1 confirms the establishment of the session.

When a session is established, the session layer protocol unit 1902 of the terminal 1
In order to execute 901, the application 1 of the server 6 is transmitted via the protocol conversion 1909 of the gateway 5.
911 and 1920 and 1921 are communicated.

According to the sequence described above, the terminal 1
Can be switched in a short time. Terminal 1
901 (1901) and the gateway connection switching with less influence on the user.

Further, as described above, since the terminal 1 has acquired the information necessary for the continuous communication with the gateway of the switching destination, the application interrupted before the gateway switching is replaced by the application from the beginning after the gateway switching. Instead of repeating, the steps after the interruption can be continued. (Embodiment 2) FIG. 2 shows a configuration of a wireless network via a public network or a private network when a gateway itself according to an embodiment of the present invention also functions as a server having information for executing a terminal application. Is shown.

The terminal 1 is, for example, a P with a built-in cellular phone.
It is a wireless information terminal such as DA (Personal Digital Assistant). The base station 2 is, for example, a simple portable telephone base station, and the network 3 is, for example, a simple portable telephone public network.

Each of the gateways 4 and 5 has a built-in server storing information 7 and information 8, respectively, and the gateways 4 and 5 are connected to the network 3. The gateways 4 and 5 have connection means for information exchange means for performing negotiation between gateways according to the present invention. The connection means for performing the negotiation between the gateways may be either wired or wireless, or may use a connection method via the network 3.

The terminal 1 is connected to the base station 2 and the network 3 and to the gateway 4 or 5, and the information 7
Alternatively, the application is executed using the information 8 of the gateway 5.

Further, as shown in FIG. 4, a configuration not via a public network or a private network may be considered.

That is, in the configuration of FIG. 4, the terminal 1 connects to the base station 2 and the gateway 4 or
0 and the gateway 5 to execute an application using the information 7 of the gateway 4 or the information 8 of the gateway 5.

In both cases of FIGS. 2 and 4, the gateway 9
Is information that includes the information 7 of the gateway 4 or has at least the same meaning as the information 7.

FIG. 10 shows a sequence in a case where the gateway 4 is stopped when the terminal 1 is connected to the gateway 4 and the terminal 1 switches the connection to the gateway 5.

The gateway switching sequence according to the second embodiment will be described below with reference to FIGS.

The application 1001 of the terminal 1 communicates with the application 1 as a server of the gateway via the session layer protocol 1002 of the terminal 1 and the session layer protocol 1004 of the gateway 4.
005 and communication 1003.

When the server switching instruction 1010 is issued from the operator while the terminal 1 and the gateway 4 are communicating as described above, the management entity 1006 of the gateway 4 transmits the communication of the terminal 1 from the gateway 4 to the gateway 4. In order to switch to 5, the negotiation with the management entity 1009 of the gateway 5 is performed.

That is, the management entity 1006 of the gateway 4 sends a session switching request 1011 to the management entity 1009 of the gateway 5.
Notify. At this time, the gateway 4 to which the gateway 4 notifies the session switching request of the switching destination can be selected based on information of another gateway stored in advance by the gateway 4 or can be specified by an operator.

Here, the information 8 of the gateway 5 is:
The information includes the information 7 of the gateway 4 used by the terminal 1 to execute the application 1001, or has at least the same meaning as the information 7.

The procedure after the session switching request 1011, ie, the session switching request 1011 → the session switching confirmation 1012 → the switching instruction 1019 → the switching notification 10
The procedure up to 13 is the session switching request 913 in FIG. 9 → the session switching confirmation 914 → the switching instruction 922 →
Since the procedure is the same as the procedure up to the switching notification 913, the detailed description is omitted here.

The session layer protocol unit 1004 of the gateway 4 notifies the address of the switching destination gateway to the session layer protocol unit 1002 of the terminal 1 by the switching notification 1013, whereby the terminal 1 communicates with the gateway 5 which is the switching destination gateway. You will know the address information.

Further, the procedure from the reception of the switching notification 1013, the procedure of the switching notification 1013 → interruption 1014 → interruption instruction 1020 → interruption confirmation 1015 → resume 1016 → resume confirmation 1017 is also the procedure described in FIG. ,
That is, the switching notification 915 → interruption 916 → interruption instruction 92
The procedure is the same as that of 3 → interruption confirmation 917 → resume 918 → resume confirmation 919, so the description is omitted here.

The session of the terminal 1 that has been interrupted is immediately restarted by the restart confirmation 1017 from the session layer protocol 1007 of the gateway 5, and when the session is restarted, the session layer protocol 1 of the terminal 1 is restarted.
002 communicates with the application 1008 of the gateway 5 to execute the application 1001;
8

As in the case of FIG.
4 to the session layer protocol means 10 of the gateway 4
04, the server connection switching sequence can be continued regardless of the state of the gateway 4;
The procedure of the interruption instruction 1020 and the interruption confirmation 1015 may be omitted, or the session layer protocol unit 1004 may autonomously notify the interruption confirmation 1015 to the session layer protocol unit 1002 of the terminal 1 without the interruption instruction 1020.

As in the case of FIG. 9, depending on the type of the gateway 4, there may be a case where only the interruption instruction 1020 is issued and the interruption confirmation 1015 is not provided. In any case, if there is no interruption confirmation 1015, the session of the terminal 1 is interrupted 1
014 is interrupted. Further, when the session layer protocol unit 1002 of the terminal 1 receives the switch notification 1013, the session layer protocol unit 1002 instructs the application 1001 to switch the gateway, and suspends 1014 according to the function of the application 1001 or the user's instruction, and changes the session layer protocol of the gateway 4. The means 1004 may be notified.

According to the sequence described above, the terminal 1
Can be switched in a short time. Terminal 1
Gateway connection switching that has little effect on the application 1001 or the user.

(Embodiment 3) FIG. 3 shows a configuration of a wireless network via a public network or a private network of a gateway connected to different servers according to an embodiment of the present invention.

The terminal 1 is a portable telephone terminal having an information processing function such as a smart phone, the base station 2 is a portable telephone base station, for example, and the network 3 is a private network, for example. The gateway 4 connects the network 3 and the server 6, and the gateway 5 connects the network 3 and the server 9.

The gateways 4 and 5 have connection means for performing negotiation between gateways by the information exchange means according to the present invention. The connection means for performing the negotiation between gateways may be either wired or wireless.
Alternatively, connection means via the network 3 may be used.

The terminal 1 connects to the server 6 via the base station 2, the network 3 and the gateway 4, and executes an application using information 7 held by the server 6. Or,
The terminal 1 connects to the server 9 via the base station 2, the network 3, and the gateway 5, and executes an application using information 8 held by the server 9.

The information 8 of the server 9 includes the information 7 of the server 6 or has at least the same meaning as the information 7.

FIG. 11 shows a sequence in a case where the gateway 4 is stopped when the terminal 1 is connected to the server 6 via the gateway 4 and the terminal 1 switches the connection between the gateway 5 and the server 9.

The gateway switching sequence according to the third embodiment will be described below with reference to FIGS.

Session layer protocol means 11 of terminal 1
02 is the application 11 of the server 6 via the gateway 4 to execute the application 1101.
08.

At this time, the communication protocol used in communication 1103 between the session layer protocol means 1102 of the terminal 1 and the session layer protocol means 1104 of the gateway 4 and the communication 1107 between the session layer protocol means 1104 of the gateway 4 and the server 6 Since the communication protocol used in the gateway 4 is different, the protocol conversion is performed by the protocol conversion unit 1105 of the gateway 4.

The communication 1103 is converted into the communication protocol used in the communication 1107 between the gateway 4 and the server 6 by the above-mentioned protocol conversion means 1105, whereby the communication between the terminal 1 and the server 6 becomes possible. However, some applications do not require protocol conversion, in which case there is no need to perform protocol conversion at the gateway.

Here, when the server switching instruction 1113 is issued from the operator while the terminal 1 and the server 6 are communicating, the management entity 1106 (information exchange means) of the gateway 4 makes the communicating terminal 1 In order for the gateway 5 and the server 9 to perform connection switching, the management entity 111 of the gateway 5
Negotiate with 1.

Hereinafter, session switching request 1114 → session switching confirmation 1115 → switching instruction 1123 → switching notification 1
The procedure up to 116 is the same as the procedure shown in FIG. 9 described above, that is, the procedure from session switching request 913 → session switching confirmation 914 → switching instruction 922 → switching notification 915.
Here, detailed description is omitted.

Session layer protocol means 11 of terminal 1
02 receives the switching notification 1116, the running application 1101
At a timing convenient for interrupting the session, for example, when communication with the H.8 is not performed, the interruption 1117 is notified to the session layer protocol unit 1104 of the gateway 4.

Hereinafter, the procedure of the interruption 117 → interruption instruction 1124 → interruption confirmation and resumption 1119 → resume confirmation 1120 is performed by the switching notification 915 → interruption 916 → interruption instruction 923 → interruption confirmation 917 and the resumption 918 → resume confirmation 919 in FIG. Since the procedure is the same as that described above, the description is omitted.

Also, as in FIG. 9, after the terminal 1 notifies the session layer protocol means 1104 of the gateway 4 of the interruption 1117, the terminal 1 can continue the server connection switching sequence regardless of the state of the gateway 4. The procedure of the instruction 1124 and the interruption confirmation 1118 is not always necessary, and when there is no interruption confirmation 1118, the session of the terminal 1 is interrupted after notifying the interruption 1117.

As in FIG. 9, when the session layer protocol unit 1102 of the terminal 1 receives the switching notification 1116, the application 1101 issues an instruction to perform a gateway switching display, or
According to the function of the application 1101 or the instruction of the user, the session layer protocol unit 1102 of the terminal 1
However, the interruption 1117 may be notified to the session layer protocol unit 1104 of the gateway 4.

By the resumption confirmation 1120 from the session layer protocol means 1109 of the gateway 5, the suspended session of the terminal 1 is resumed. When the session resumes, the session layer protocol means 1 of the terminal 1
Reference numeral 102 denotes an application 111 of the server 9 via the gateway 5 to execute the application 1101.
2 and 1121 and 1122.

According to the sequence described above, the terminal 1
Can be switched in a short time. Terminal 1
Gateway switching that has little effect on the application 1101 or the user.

(Embodiment 4) A specific application example of the gateway switching sequence according to the configuration of FIG. 1 will be described below with reference to FIGS.

FIG. 12 shows that the gateway 4 is stopped when the user is connected to the WWW server software of the server 6 from the terminal 1 via the gateway 4 using the WWW browser, and the terminal 1 is moved from the gateway 4 to the gateway 5. The sequence when switching to connection is shown.

The session layer protocol means 1202 communicates a command issued by the user using the WWW browser 1201 of the terminal 1 with the WWW server software 1211 of the server 6 via the gateway 4.

At this time, the communication protocol between the session layer protocol means 1202 of the terminal 1 and the session layer protocol means 1204 of the gateway 4 is a wireless communication protocol, and is used between the session layer protocol means 1204 of the gateway 4 and the server 6. The communication protocol is HTTP (Hyper Text Transfer Protocol). Therefore, protocol conversion is performed by the protocol conversion means 1205 of the gateway 4 in order to obtain consistency between the two.

Here, for example, when the user operates the WWW browser 1201 of the terminal 1 and gives an instruction to access a file stored in the server 6 //www.xxx/xyz.htm, the wireless communication protocol Command INVOKE <REQUEST (g
et, // www.xxx/xyz.htm)>1203 is the HTTP command REQUEST (get, // ww
(w.xxx/xyz.htm) 1207 and transmitted to the server 6.

The WWW server software 1211 of the server 6 executes the command REQUEST (get, //www.xxx/xyz.htm) 1207
Is received, the data of the file //www.xxx/xyz.htm is transmitted by RESPONSE (data) 1212.

This HTTP response RESPONSE (data) 1
212 is a protocol conversion means 1205 of the gateway 4
The response REPLY <RESP of the wireless communication protocol
It is converted to ONSE (data)> 1213 and transmitted from the session layer protocol means 1204 of the gateway to the terminal 1. As a result, communication between the terminal 1 and the server 6 becomes possible, and the user can browse the data of the file //www.xxx/xyz.htm of the server 6 using the WWW browser 1201.

When the terminal 1 and the server 6 are communicating as described above, a server switching instruction 121 from the operator is issued.
4 is issued, the management entity 1206 of the gateway 4 sets the communicating terminal 1 to the gateway 5.
Negotiate with the management entity 1210 of the gateway 5 in order to make the connection switch.

That is, the management entity 1206 of the gateway 4 sends a session switching request 1215 to the management entity 1210 of the gateway 5.
Notify. Hereinafter, session switching confirmation 1216 → switching instruction 1217 → switching notification 1218, and interruption 12
19 → interruption instruction 1220 → 1221 What is the procedure from interruption confirmation? In FIG. 9 described above, session switching confirmation 914 → switching instruction 922 → switching notification 915, and interruption 916
The procedure is the same as the procedure of → interruption instruction 923 → interruption confirmation 917, so detailed description is omitted.

Also, as in FIG. 9, after the terminal 1 notifies the session layer protocol means 1204 of the gateway 4 of the interruption 1219, the server connection switching sequence can be continued regardless of the state of the gateway 4, so that the interruption The procedure of the instruction 1220 and the interruption confirmation 1221 is not necessarily required, and the session layer protocol unit 1204 autonomously transmits the interruption confirmation 1221 without the interruption instruction 1220 to the session layer protocol unit 120 of the terminal 1.
2 may be notified.

Also, depending on the type of the gateway 4, there may be a case where only the interruption instruction 1220 is issued and the interruption confirmation 1221 is not provided. In any case, when there is no interruption confirmation 1221, the session of the terminal 1 is interrupted after notifying the interruption 1219.

At this time, the WWW browser 1201
If the data of //www.xxx/xyz.htm has already been received, the user can continue to browse the data even if the session is interrupted. Of course, it is not necessary to interrupt the execution of the WWW browser 1201, which is an application of the terminal 1.

Session layer protocol means 12 of terminal 1
02 receives the switching notification 1218, performs a gateway switching display on the WWW browser 1201, and displays the terminal 1 according to the function of the WWW browser 1201 or a user's instruction.
The session layer protocol means 1202 of the
9 to the session layer protocol means 12 of the gateway 4
04 may be notified.

[0114] Notification of resumption 1222 from terminal 1 and
The notification of the resumption confirmation 1223 from the gateway 5 is shown in FIG.
Are the same as the restart 918 and the restart confirmation 919 shown in FIG.

According to the above procedure, the suspended terminal 1
Session will resume.

In this state, when the user operates the WWW browser 1201 of the terminal 1 to give an instruction to access the file //www.xxx/xyz.htm, the wireless communication protocol command INVOKE <REQUEST (get, //www.xxx/xyz.htm)>1
224 is a protocol conversion unit 120 of the gateway 5
9 and the HTTP command REQUEST (get, //www.xxx/xy
z.htm) is converted to 1225 and transmitted to the server 6.

When the WWW server software 1211 of the server 6 receives the command REQUEST (get, //www.xxx/xyz.htm) 1225, the data of the file //www.xxx/xyz.htm is received.
RESPONSE (data) 1226.

HTTP response RESPONSE (data) 122
Reference numeral 6 denotes a response REPLY <RESPONSE of the wireless communication protocol by the protocol conversion unit 1209 of the gateway 5.
(Data)> 1227, and is transmitted from the session layer protocol unit 1208 of the gateway 5 to the terminal 1.

Thus, communication between the terminal 1 and the server 6 using the gateway 5 becomes possible, and the user can use the WWW browser 1201 to access the file //www.xx
You can browse the data of x / xyz.htm.

(Generation of New Communication During Negotiation) A sequence when a new communication occurs between the terminal and the server during the negotiation will be described with reference to FIG.

The session switching request from the gateway 4 to the gateway 5 and the accompanying instruction and confirmation between the session layer protocol means of the gateway 5 and the management entity are the same as those in FIG.

FIG. 13 shows a state in which communication between the terminal 1 and the server 6 has occurred before the confirmation of session switching from the gateway 5 to the gateway 4 is notified.

For this reason, the information indicating the communication state between the terminal 1 and the gateway 4 included in the information notified by the gateway 4 to the gateway 5 by the session switching request, and the terminal 1 and the server before the notification of the session switching confirmation are transmitted. The communication state of the terminal 1 and the gateway 4 after the communication has been performed by the terminal 6 does not match.

That is, the information indicating the communication state between the terminal 1 and the gateway 4 or 5 is indicated by the T in the left end of FIG.
ID. Here, the TID notified by the session switching request from the gateway 4 to the gateway 5 is TID = 1 shown at the top. The TID after the terminal 1 and the server 6 have communicated is TID = 2 shown in the middle row. In this state, TID1 notified to the gateway 5
Since the actual TID2 is different from the actual TID2, the communication process between the gateway 5 and the terminal 1 after the gateway connection switching may become abnormal.

As described above, even if the communication between the terminal 1 and the server 6 occurs during the negotiation between the gateways, the TI
In order to maintain the consistency of D, the latest TID, TI in FIG.
D = 2 is also notified at the time of the restart notification from the terminal 1 to the gateway 5. (Switching process of a plurality of terminals) Next, the stop timing of a gateway connected to a plurality of terminals will be described with reference to FIG.

The gateway 4 is connected to the terminals 1, 15, and 17. Here, the session switching negotiation between the gateway 4 and the gateway 5 is the same as in FIG.

In FIG. 14, the terminal 1, the terminal 17 and the terminal 15 are handled by one session switching negotiation, but the negotiation may be performed separately for each terminal.

Session switching negotiation between gateway 4 and gateway 5 (session switching request 14
01 → session switching confirmation 1402), the gateway 4 sends a switching notification to each of the terminal 1, the terminal 17, and the terminal 15. Then, terminal 1, terminal 17, terminal 15
Notifies the gateways 4 of the interruptions 1403a, 1403b, and 1403c, respectively, and receives the interruptions 1404a, 1404b, and 1404c for each connected terminal, and then the gateway 4 confirms the interruptions 1405a, 1405a.
405b and 1405c are issued and stopped.

Apart from the above, the gateway 4 has an allowable time from the switching notification to the terminal to the interruption notification to the gateway 4, and if the allowable time has passed, there is a terminal that has not notified the gateway 4 of the interruption. Can also be considered.

(When the Switching Destination Gateway Refuses) Next, the sequence when the connection switching of the terminal is rejected from the switching destination gateway by negotiation will be described with reference to FIG.

The sequence until the gateway 4 notifies the gateway 5 of the session switching request is the same as in FIG. The gateway 5 sends a session switching rejection 1501 to the gateway 4 due to insufficient capacity or excessive load.
Notify. Upon receiving the session switching rejection 1501, the gateway 4 notifies the gateway 16 of the session switching request 1502 as a new switching destination, and the gateway 1
6 is capable of accommodating terminals, gateway 16
Notifies the gateway 4 of the session switching confirmation 1503, and thereafter the connection switching is executed.

Even if the connection switching is rejected by the switching destination gateway, the gateway 4 negotiates with a new switching destination gateway to search for a connection switching destination gateway. This function is to be possessed by the management entity of the gateway 4 of the switching source. However, in the memory of the gateway 4, a plurality of switching destination gateways are registered in a state in which priorities are assigned in advance, and the management entity notifies the rejection notification. When receiving the information, the next candidate switching destination gateway may be read out from the memory to automatically execute the information exchange procedure.

(When the switching destination gateway has insufficient capacity)
Next, a sequence when the switching destination gateway notifies that the terminal does not have the terminal accommodation capability together with the session switching confirmation notification by negotiation will be described with reference to FIG.

The sequence until the gateway 4 notifies the gateway 5 of the session switching request is the same as in FIG.

When the gateway 5 cannot provide all the resources required by the terminal from the information such as the maximum data length and the window size notified together with the session switching request from the gateway 4, the gateway 5 confirms the session switching.
In conjunction with 601, the upper limit of the resources that can be provided to the terminal requesting connection switching is notified to the gateway 4.

The gateway 4 notifies the terminal 1 of the upper limit of the resources that can be provided by the gateway 5 together with the switching notification 1602. As a result, the terminal 1 changes its capability, that is, its own capability information to match the upper limit of the resources that the gateway 5 can provide.

As a result, after switching the connection to the gateway 5, the terminal 1 performs communication with the changed capability. The switching source gateway 4 may be provided with a determination unit for determining whether the communication between the switching destination gateway 5 and the terminal 1 is possible, and when the communication is not possible, the communication may be stopped. Further, the terminal may be provided with a judgment means for judging whether or not communication is possible with the capability notified as described above, and when communication is not possible, reception of the service may be stopped.

(When there is a retransmission procedure) FIG.
3 shows a sequence in the case where the data retransmission protocol is incorporated in the gateway 4 and the gateway 5. In FIG. 19, the retransmission protocol is located below the session layer, but it goes without saying that the retransmission protocol may be incorporated in the session layer.

As described with reference to FIG. 12, the command INVOKE
<REQUEST (get, // www.xxx/xyz.htm)> 1203 is converted into an HTTP command REQUEST by the protocol conversion unit 1205.
(get, /// www.xxx/xyz.htm) Converted to 1207 and server 6
Is transmitted to the gateway 4, the session layer protocol means 1204 of the gateway 4 transmits the ACK 12 of the wireless communication protocol.
28 to the session layer protocol means 1202 of the terminal 1. The terminal 1 receives the ACK 1228, and thereby executes the command INVOK <EREQ of the wireless communication protocol.
It is determined that UEST (get, //www.xxx/xyz.htm)>1203 has been received by the gateway 4.

Also, as described above, the HTTP response RESP
When the ONSE (data) 1212 is converted by the protocol conversion means 1205 of the gateway 4 into a response REPLY <RESPONSE (data)> 1213 of the wireless communication protocol and transmitted to the terminal 1 from the session layer protocol means 1204 of the gateway, the response REPLY <RESPONSE (data)
> 1213, the session layer protocol unit 1202 of the terminal 1 transmits the ACK 1230 of the wireless communication protocol.
Is transmitted to the gateway 4. By receiving the ACK 1230 of the wireless communication protocol, the gateway 4 determines that the terminal 1 has received the response REPLY <RESPONSE (data)> 1212 of the wireless communication protocol.

Further, after the restart confirmation 1223, the command INVOKE <REQUEST (get, ///www.xxx/xy
z.htm)> 1224 indicates the HTTP command REQUEST (get, /// w
ww.xxx/xyz.htm) 1225 and transmitted to the server 6. At this time, the session layer protocol unit 1208 of the gateway 5 transmits the ACK12 of the wireless communication protocol.
31 is transmitted to the session layer protocol means 1202 of the terminal 1. In addition, response REPLY <RESPONSE (data)> 1
The session layer protocol unit 1202 of the terminal 1 that has received the 227 transmits the wireless communication protocol ACK1233 to the gateway 5.

Here, the retransmission protocol in the terminal 1, the gateway 4, and the gateway 5 will be described with reference to FIG.

When the terminal 1 receives the command IN of the wireless communication protocol
After transmitting VOKE <REQUEST (get, // www.xxx/xyz.htm)>1309, the gateway 4 sends ACK1 of the wireless communication protocol.
If 314 is not received within the specified time, the retransmission protocol 1303 of the terminal 1 uses the wireless communication protocol command INVO.
KE <REQUEST (get, //www.xxx/xyz.htm)> 1310 is retransmitted.

If ACK 1314 of the wireless communication protocol is returned from gateway 4, terminal 1 stops retransmission. The terminal 1 has a timer for measuring the specified time, and also has a maximum predetermined value of the number of retransmissions. If the number of retransmissions exceeds the maximum predetermined value, the terminal 1 disconnects the communication assuming that some abnormality has occurred in the communication between the terminal 1 and the gateway 4.

Similarly, after the gateway 4 has transmitted the response REPLY <RESPONSE (data)> 1316 of the wireless communication protocol, the terminal 1 sends an ACK 1319 of the wireless communication protocol from the terminal 1.
Is not received within the specified time, the retransmission protocol 1304 of the gateway 4 responds to the wireless communication protocol.
REPLY <RESPONSE (data)> 1317 is retransmitted.

If ACK 1319 of the wireless communication protocol is returned from terminal 1, gateway 4 stops resending. Further, the gateway 4 has a timer for measuring the specified time, and also has a maximum predetermined value for retransmission. If the number of retransmissions exceeds the maximum predetermined value, the gateway 4 disconnects the communication assuming that some abnormality has occurred in the communication between the terminal 1 and the gateway 4.

(Interruption Display) FIG. 17 shows a sequence for performing interruption display to the user.

The sequence up to the switch notification 1714 is shown in FIG.
Description is omitted because it is the same as 2.

Session layer protocol means 17 of terminal 1
02 notifies the interruption 1714 to the session layer protocol unit 1704 of the gateway 4 and issues an interruption display notification 1708 to the application 1701 of the terminal 1 at this time. The application 1701 performs the above-described interruption display notification 17
08, the interruption display 1709 is executed on the screen of the terminal 1.

In the suspended display 1709, the message "Gateway 4 stops because of version upgrade work.
For example, a message that the user can clearly understand that there is no failure or failure of the gateway, the terminal, or the network, such as "switch connection to gateway 5".

Thereafter, the session layer protocol unit 1702 of the terminal 1 notifies the session layer protocol unit 1710 of the gateway 5 of the restart 1711, and the session layer protocol unit 1710 of the gateway 5 confirms the restart 1
712 to the session layer protocol unit 170 of the terminal 1
Notify 2.

Alternatively, the session layer protocol unit 1702 of the terminal 1 may notify the session layer protocol unit 1710 of the gateway 5 of the resumption 1711 by the user's instruction while the suspended display 1709 is displayed.

Session layer protocol means 17 of terminal 1
02, upon receiving the restart confirmation 1712, notifies the application 1701 of the restart display 1713, and upon receiving the restart display 1713, the application 1701 displays the suspended display 113.
709 is terminated.

[0154] In addition to the above-mentioned display during suspension, when a stop notification is received from the switching source gateway as described above, the notification can be displayed.

(Generation of Wireless Communication Protocol After Switching Notification) FIG. 21 shows a sequence when a wireless communication protocol command is generated from the terminal 1 immediately after the switching notification. Here, the concept of a transaction is used. Introduce.

That is, the logical connection between the terminal 1 and the gateway 4 is called a session, and the actual application data communication is called a transaction. The transaction indicates a series of operation processing of a response from the server corresponding to a request or notification from the user or a response from the user corresponding to the request or notification from the server. Here, there are a plurality of transactions for one session. Also, an identifier (transaction ID) is provided for each transaction so that the corresponding request / notification / response can be identified.

The sequence up to the switching notification 1713 is the same as that in FIG.

The gateway 4 has already sent the gateway switching notification 1713 to the session layer protocol
702, the wireless communication protocol command INVOKE <REQUEST (get, //www.xxx/xyz.htm)>1719
Holds the contents of

Session layer protocol means 17 of terminal 1
02, upon receiving the switching notification 1713, notifies the session layer protocol unit 1705 of the gateway 4 of the interruption 1714. The session layer protocol means 1705 of the gateway 4 notifies the management entity 1707 of the reception of the interruption 1714, and
707 is a management entity 1 of the gateway 5
To 711, transaction information (transaction status, transaction ID, etc., and wireless communication protocol command INVOKE <REQUEST (get, // www.xxx/xyz.htm)>
1716).

The subsequent procedure, that is, the interruption confirmation 171
The sequence of 5 → resume 1717 → resume confirmation 1718 is the interruption confirmation 917 → resume 918 → resume confirmation 91 in FIG.
Since the sequence is the same as the sequence of No. 9, the description is omitted. When the session between the session layer protocol unit 1702 of the terminal 1 and the session layer protocol unit 1709 of the gateway 5 is resumed, the transaction information 171 is transmitted to the session layer protocol unit 1709 of the gateway 5.
Using the transaction status and transaction ID received in step 6, the protocol conversion means 1710 converts the contents of REQUEST into the HTTP command REQUEST (get, //www.xxx/x
yz.htm) is converted to 1720 and requested to the server 6.

ACK1 of the subsequent wireless communication protocol
Since the sequence up to 725 is the same as in FIG. 19, the description is omitted.

Here, the command INVOKE <REQUEST (get, ///www.xxx/xy) of the wireless communication protocol transmitted from the terminal 1
z.htm)> 1719 is converted by the protocol conversion unit 1706 of the gateway 4 into the HTTP command REQUEST (get, // w
(ww.xxx/xyz.htm) may be converted to 1720 and then transmitted to the management entity 1711 of the gateway 5 in the transaction information 1716.

Although the management entity 1707 of the gateway 4 communicates with the management entity 1711 of the gateway 5 after receiving the interruption 1714, the communication may be performed before receiving the interruption 1714.

Also, even when the terminal 1, the gateway 4, and the gateway 5 do not transmit ACK, the same procedure as the sequence for not transmitting the ACKs 1722 and 1725 of the wireless communication protocol can be performed. That is, the ACK procedure is not always necessary.

The same procedure can be performed when the terminal 1, the gateway 4 and the gateway 5 incorporate a retransmission protocol.

(Switching instruction before response generation from server) Next, referring to FIG.
Receives a command of the wireless communication protocol from the gateway 4 and sends the corresponding wireless communication protocol AC to the terminal 1 from the gateway 4.
A sequence in the case where K has been transmitted, but an instruction to switch the server has been issued from the operator of the gateway 4 before receiving the HTTP response from the server 6 will be described.

In FIG. 22, except for the point that no HTTP response has been generated from the server 6 and that the terminal 1 has not generated an ACK corresponding to the HTTP response, the sequence up to the switching notification 1813 is as shown in FIG. Therefore, the description is omitted.

The gateway 4 transmits the HT sent to the server 6
TP command REQUEST (get, // www.xxx/xyz.htm) 182
3 from the server 6 to the corresponding HTTP response RE
It is held until SPONSE (data) 1819 is received.

The session layer protocol means 18 of the terminal 1
02, upon receiving the switching notification 1813, notifies the session layer protocol unit 1805 of the gateway 4 of the interruption 1814. The session layer protocol unit 1805 of the gateway 4 notifies the management entity 1807 of the reception of the interruption 1814, and issues an HTTP command REQUES.
An HTTP response RESPONSE (data) 1819 is received from the server 6 corresponding to T (get, //www.xxx/xyz.htm) 1823. As a result, the protocol conversion means 1806 of the gateway 4 sends the HTTP command REQUEST (get, /
/www.xxx/xyz.htm) is converted into a response (data corresponding to REPLY <RESPONSE (data)> 1820 described later) of the wireless communication protocol.

Thereafter, the transaction information (transaction state, transaction ID, etc., and the converted response REPLY <RE of the wireless communication protocol are transmitted to the management entity 1811 of the gateway 5 via the management entity 1807 of the gateway 4.
SPONSE (data)> content 1816 is notified.

The subsequent interruption confirmation 1815 and resumption sequences are the same as those in FIG. Session layer protocol means 1802 of terminal 1 and gateway 5
When the session of the session layer protocol unit 1809 of the gateway 5 is resumed, the session layer protocol unit 1809 of the gateway 5 checks the state of the transaction
D, a response REPLY <RESPONSE (data)> 1820 of the wireless communication protocol is transmitted from the session layer protocol unit 1809 to the session layer protocol unit 1 of the terminal 1.
802.

The sequence of ACK1821 of the radio communication protocol is the same as that of FIG.

Here, the response REPLY <RESPONSE (data) 1819 of the HTTP protocol transmitted from the server 6
Is not converted by the protocol conversion means 1806 of the gateway 4, is transmitted from the management entity 1807 of the gateway 4 to the management entity 1811 of the gateway 5 in transaction information 1816, and is converted by the protocol conversion means 1810 of the gateway 5.
May be converted to a response REPLY <RESPONSE (data)> 1820 of the wireless communication protocol.

Even when ACK is not transmitted between the terminal 1 and the gateways 4 and 5, the same procedure can be performed in a sequence in which ACKs 1824 and 1821 of the wireless communication protocol are not transmitted. The ACK procedure is not always necessary.

At this time, as shown in FIG. 21, the same sequence as in FIG. 21 in which the REQUEST content is notified to the gateway 5 by the transaction information 1816 and the HTTP command is transmitted from the gateway 5 to the server 6 can be performed. . Also, the same procedure can be performed when the terminal 1, the gateway 4 and the gateway 5 incorporate a retransmission protocol.

(When there is no ACK from the terminal) Next, referring to FIG. 23, the gateway 4 receives a command of the wireless communication protocol from the terminal 1, receives an HTTP response from the server 6, Is transmitted to the terminal 1 but no ACK of the wireless communication protocol is returned from the terminal 1, and a sequence in a case where a server switching instruction is issued from the operator of the server 4 will be described.

Response REPLY <RESPONSE (data)> 192
The sequence up to the switching notification 1913 is the same as that in FIG. 19 except that the ACK from the terminal 1 to the gateway 4 is not returned to the gateway 4, and the description is omitted.

However, during this time, the response REPL
The retransmission control of Y <RESPONSE (data)> 1924 is performed by the retransmission protocol 1904 of the gateway 4.

Session layer protocol means 19 of terminal 1
02, upon receiving the switching notification 1913, notifies the session layer protocol unit 1905 of the gateway 4 of the interruption 1914.

The session layer protocol means 1905 of the gateway 4 notifies the reception of the interruption 1914 to the management entity 1907, and the management entity 1907 sends the transaction information (transaction state, transaction ID retransmission number, retransmission number) to the management entity 1911 of the gateway 5. The elapsed value of the timer value and the response RE of the wireless communication protocol
PLY <RESPONSE (data)>) 1916 is notified.

The subsequent interruption confirmation 1915 and resumption sequences are the same as in FIG.

Session layer protocol means 19 of terminal 1
02 and the session layer protocol means 1 of the gateway 5
When the session 909 is resumed, the session layer protocol unit 1909 of the gateway 5 uses the transaction status, transaction ID, retransmission count, and retransmission timer value received in the transaction information 1916 to generate the contents of RESPONSE (data) 1926. From the retransmission protocol 1908 to the session layer protocol means 1902 of the terminal 1.

The sequence of ACK 1927 of the wireless communication protocol is the same as that of FIG.

Here, the RESPONCE (data) 1923 is once converted into REPLY <RESPONSE (data)> of the wireless communication protocol by the protocol conversion means 1906 of the gateway 4. However, the content of the RESPONSE (data) included in the transaction information 1916 from the management entity 1907 of the gateway 4 and transmitted to the management entity 1911 of the gateway 5 is in the format of a response REPLY <RESPONSE (data) of the HTTP protocol, and May be converted again into the response REPLY <RESPONSE (data)> 1926 of the wireless communication protocol by the protocol conversion unit 1910 of FIG.

The gateway 4 and the gateway 5
In the case where ACK is not transmitted, the same procedure as the sequence in which ACK1922 of the wireless communication protocol is not transmitted can be performed.

The same procedure can be performed when the terminal 1 and the gateway 5 incorporate a retransmission protocol.

According to the above-described sequence, the gateway connection of the terminal can be switched even when the application of the terminal has not received the data corresponding to the request, and the gateway connection of the terminal with little influence on the application and the user can be performed. it can.

(Embodiment 5) There is no connection route between gateways, and connection between gateways via a network or connection between a plurality of gateways and servers cannot be negotiated between gateways. Even with the configuration described above, effects can be obtained by implementing the present invention.

FIG. 5 and FIGS. 24, 25, 26, 2
The gateway switching sequence when there is no information crotch means between the gateways in the fifth embodiment will be described using FIG. Gateways 11 and 12 are server 6
And the network 3 and the server 6 are connected. Further, the gateways 11 and 12 have no information exchange means for executing negotiation between the gateways. Terminal 1
Connects to the server 6 via the base station 2 and the network 3 and the gateway 11 or 12, and executes an application using information 7 held by the server 6.

The session layer protocol means 20 of the terminal 1
02 is the application 2 of the server 6 via the gateway 11 to execute the application 2001.
Communicate with 011. At this time, the communication protocol used in the communication 2003 between the session layer protocol means 2002 of the terminal 1 and the session layer protocol means 2004 of the gateway 11 and the communication 200 between the session layer protocol means 2004 of the gateway 11 and the server 6
7, the protocol conversion is performed by the protocol conversion means 2005 of the gateway 11.

The communication 2003 is converted into the communication protocol used in the communication 2007 between the gateway 11 and the server 6 by the above-mentioned protocol conversion means 2005, whereby the communication between the terminal 1 and the server 6 becomes possible. However, some applications do not require protocol conversion, in which case the gateway does not perform protocol conversion.

When the server switching instruction 2012 is issued from the operator while the terminal 1 and the server 6 are communicating, the management entity 2 of the gateway 11
006, the session layer protocol means 20 for causing the gateway 12 to switch the connection between the communicating terminal 1
04, a switching instruction 2013 is performed.

The session layer protocol means 2004 sends information such as the gateway address of the switching destination to the session layer protocol
Notify 2. At this time, the switching destination gateway notified by the gateway 11 can be selected by searching for a gateway capable of accommodating the terminal 1 based on information of another gateway stored in advance by the gateway 11, or by specifying from the operator. It is.

The terminal 1 first knows the address information of the gateway 12, which is the switching destination gateway, by the switching notification 2014. That is, the terminal 1 receives the information for switching the server connection according to the switching notification 2014 from the gateway 11, and stores the information of the plurality of gateways for the gateway connection switching in the internal storage means of the terminal 1, for example, a hard disk, an IC card, and
OM, EEPROM, battery-backed RA
There is no need to always save it in M or the like.

Session layer protocol means 20 of terminal 1
02, upon receiving the switching notification 2014, the running application 2001
For example, when communication is not performed with No. 1, the interruption 2015 is notified to the session layer protocol unit 2004 of the gateway 11 at a timing convenient to interrupt the session.

The session layer protocol means 2004 of the gateway 11 notifies the reception of the interruption 2015 to the management entity 2006, and the management entity 2006 notifies the session layer protocol means 2004 of the interruption instruction 2016.

When the session layer protocol means 2004 of the gateway 11 receives the interruption instruction 2016, the session layer protocol means 20 of the terminal 1
02 is notified.

Thereafter, the session layer protocol means of the terminal 1 is interrupted.

However, after notifying the session 2015 to the session layer protocol means 2004 of the gateway 11, the terminal 1 can continue the server connection switching sequence regardless of the state of the gateway 11.

Therefore, the interruption instruction 2016 and the interruption confirmation 2017 may be omitted, or the session layer protocol means 2004 autonomously performs the interruption confirmation 2017 of the terminal 1 without the interruption instruction 2016.
02 may be notified. Further, depending on the type of the gateway 4, there may be a case where only the interruption instruction 2016 is performed and the interruption confirmation 2017 is not provided.

In any case, if there is no interruption confirmation 2017, the session of the terminal 1 is interrupted after notifying the interruption 2015. Further, when the session layer protocol unit 2002 of the terminal 1 receives the switching notification 2014, it performs a gateway switching display to the application 2001, and according to the function of the application 2001 or an instruction of the user, the session layer protocol unit 20 of the terminal 1 is displayed.
02 may notify the interruption 2015 to the session layer protocol means 2004 of the gateway 11.

The session layer protocol means 20 of the terminal 1
02 notifies the session layer protocol unit 2008 of the gateway 12 of a restart 2018 including information such as a terminal address, a session ID, a maximum data length, and a window size.

Upon receiving the resumption 2018, the session layer protocol means 2008 of the gateway 12 notifies a resumption confirmation 2019. Next, restart confirmation 201 from session layer protocol means 2008 of gateway 12 is performed.
9, the suspended session of the terminal 1 is resumed.

When the session resumes, the session layer protocol means 2002 of the terminal 1
01, the communication 2020, 2021 with the application 2011 of the server 6 via the protocol conversion means 2009 of the gateway 12.

The sequence described above is based on the premise that the gateway 11 notifies the terminal 1 of a gateway capable of accommodating the terminal 1 as a switching destination gateway. Therefore, if it is determined that the switching destination gateway does not have the capacity to accommodate the terminal 1 after the connection switching to the switching destination gateway, the inefficient connection switching to switch the connection to another gateway again does not occur. . The application 20 of the terminal 1
01 and gateway connection switching with little effect on the user.

Referring to FIG. 25, a sequence in the case where a command of the wireless communication protocol is generated from terminal 1 immediately after switching notification 2113 will be described.

The sequence up to the switching notification 2113 is the same as that in FIG. 24, and the description is omitted.

Protocol conversion means 21 of gateway 4
06 is a wireless communication protocol command INVOKE <REQUEST
(get, // www.xxx/xyz.htm) 2119 is converted to HTTP command RE
QUEST (get, //www.xxx/xyz.htm) 2116 and sends it to the server 6. Here, when the gateway 4 notifies the server 6 of the HTTP command REQUEST (get, //www.xxx/xyz.htm) 2116, the REQUEST (get, //www.xxx/xy)
z.htm) The address of the gateway that transmits RESPONSE (data) (here, 2122) corresponding to 2116 is notified.

In the above description, the HTTP command and the notified address can be treated as different information, and can be included in the HTTP command. In the latter case, the server 6 analyzes the HTTP command and extracts the address portion.

The subsequent interruption confirmation 2115 and resumption sequences are the same as in FIG. 24, and will not be described.

Thereafter, when the session between the session layer protocol unit 2102 of the terminal 1 and the session layer protocol unit 2109 of the gateway 5 is resumed, the session layer protocol unit 2109 of the gateway 5 checks the state of the transaction Using the ID, the wireless communication protocol AC
K2121 is transmitted to the terminal 1. The HTTP response RESPONSE (data) 2122 corresponding to the HTTP command REQUEST (get, //www.xxx/xyz.htm) 2116 from the server 6 is received, and the protocol conversion unit 2110 receives the response REPLY <RESPONSE of the wireless communication protocol. > (Data) 2123 and transmit it to the session layer protocol unit 2102 of the terminal 1. Here, ACK 212 of the wireless communication protocol is used.
1 is a session layer protocol means 2 of the gateway 4
The information may be transmitted from the terminal 105 to the terminal 1.

ACK 212 of the following wireless communication protocol
The sequence up to 4 is the same as in FIG.

Next, referring to FIG.
Then, a command of the wireless communication protocol (command INVOKE <REQUEST (get, // www.xxx/xyz.htm)> 2222
→ Command REQUEST (get, // www.xxx/xyz.htm) 222
3) and the ACK 2224 from the gateway 4 has been transmitted, but before receiving the HTTP response corresponding to the HTTP command from the server 6, the gateway 4
A sequence when a server switching instruction is issued from this operator will be described.

The sequence up to the switch notification 2213 is the same as that shown in FIGS.

Session layer protocol means 22 of terminal 1
02, upon receiving the switching notification 2213, notifies the session layer protocol means 2205 of the gateway 4 of the interruption 2214.

The session layer protocol means 2205 of the gateway 4 notifies the reception of the interruption 2214 to the management entity 2207, and the management entity 2207 of the gateway 4 sends an HTTP response RESPONSE (data) 2216 to the server 6 to the gateway 5. Is notified 2225.

The subsequent interruption confirmation 2215 and resumption sequence are the same as in FIG.

Session layer protocol means 22 of terminal 1
02 and the session layer protocol means 2 of the gateway 5
When the session 209 is restarted, the session layer protocol unit 2209 of the gateway 5 restarts the session 221.
HTTP response RE from the server 6 using the transaction status and transaction ID received in Step 7
SPONSE (data) 2216 is received, and the protocol conversion means 2210 receives the response REPLY <RESP of the wireless communication protocol.
Convert to ONSE (data)> 2220 and send to terminal 1.

The sequence of ACK 2221 of the wireless communication protocol is the same as that of FIG.

Next, referring to FIG.
Then, the wireless communication protocol command is received from the terminal 1, the HTTP response is received from the server 6, and the wireless communication protocol response is transmitted to the terminal 1.
The following describes a sequence in the case where an ACK of the wireless communication protocol is not returned from the server and a server switching instruction is issued from the operator of the server 4.

The sequence up to the switch notification 2313 is the same as that shown in FIGS. 19 and 24, and a description thereof will be omitted. However,
During this time, the response REPLY <RESP shown in FIG.
Retransmission control of ONSE (data)> 2324 is performed in the retransmission protocol 2304 of the gateway 4.

Hereinafter, the sequence of FIG. 27 will be described from the continuation.

Session layer protocol means 23 of terminal 1
02, upon receiving the switching notification 2313, notifies the session layer protocol unit 2305 of the gateway 4 of the interruption 2314.

The session layer protocol means 2305 of the gateway 4 notifies the management entity 2307 of the reception of the interruption 2314.

The session layer protocol means 2305 of the gateway 4 executes the HTTP command REQUEST (get, //www.x
xx / xyz.htm) 2320 is held until ACK 2329 of the wireless communication protocol from terminal 1 is received. In this state, the gateway 4 transmits an HTTP command REQUEST (get, //www.xxx/xyz.htm) 2316 to the server 6.

When the gateway 4 receives the HTTP command REQUEST
(get, // www.xxx/xyz.htm) 2316 is notified to the server 6 when the REQUEST (get, // www.xxx/xyz.htm) 2316
Is notified of the address of the gateway that transmits RESPONSE (data) (here, 2327) corresponding to.

In the above description, the HTTP command and the notified address can be treated as different information, and can be included in the HTTP command. In the latter case, the server 6 analyzes the HTTP command and extracts the address portion.

The subsequent interruption confirmation 2315 and resumption sequence are the same as in FIG.

Session layer protocol means 23 of terminal 1
02 and the session layer protocol means 2 of the gateway 5
When the session 309 is resumed, the session layer protocol unit 2309 of the gateway 5 resumes 231
7, the HTTP response (data) 2327 is received from the server 6 using the transaction status and the transaction ID received by the server 7, and the protocol conversion means 2310 sends a response <REPLY (data)> 232 of the wireless communication protocol.
8 and the session layer protocol means 23 of the terminal 1
02.

ACK232 of the subsequent wireless communication protocol
The sequence up to 9 is the same as in FIG.

According to the above-described sequence, even when there is no negotiation means between gateways,
The gateway connection of the terminal can be switched even when the application of the terminal has not received the data corresponding to the request, and the gateway connection can be switched with little influence on the application of the terminal and the user.

In the embodiment described above, the switching source gateway is stopped after the connection is switched. However, it is not essential to stop the switching, and the switching gateway may continue to operate.

As described above, it is assumed that there is a switching instruction when the terminal is receiving the service from the server, but the present invention is not limited to the above. In other words, even when the above service is not received, only the switching notification may be sent to the terminal from the switching source gateway, and the switching gateway may be required to start communication with the switching destination gateway in addition to the notification. Information may be sent to the terminal.

[0234]

As described above, according to the present invention, even when a gateway connected to a terminal stops, a connection switching negotiation is performed between the gateways prior to the stop of the gateway. An advantageous effect is obtained that it is possible to reconnect to another gateway having a terminal accommodation capacity in a short time without terminating.

The gateway can be switched even if the application has not received the data corresponding to the request. In short, the switching source gateway transfers the transaction state to the switching destination gateway, so that the terminal can perform gateway switching without being conscious of the transaction state.

Even when the connection switching negotiation cannot be performed directly between the gateways, the gateway can be switched even if the application has not received the data corresponding to the request, and the gateway can be switched to another gateway having a terminal accommodating capacity. Connection in a short time.
In either case, it is not necessary for the terminal to always hold information on a plurality of gateways, so that the terminal can easily cope with changes in the network configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wireless network via a public network or a private network of a gateway sharing a server according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a wireless network via a public network or a private network in which a gateway itself has information according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a wireless network via a public network or a private network of a gateway connected to different servers according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a wireless network according to an embodiment of the present invention that does not pass through a public or private network in which a gateway itself has information.

FIG. 5 is a configuration diagram of a wireless network according to a conventional form in which a gateway sharing a server is via a public network or a private network.

FIG. 6 is a configuration diagram of a conventional wireless network that does not pass through a public network or a private network in which a gateway itself has information.

FIG. 7 is a diagram showing the positioning of a session layer protocol and a session layer management entity in a protocol stack of a terminal and a gateway.

FIG. 8 is a conventional gateway switching sequence diagram in the configuration of FIG. 6;

9 is a gateway switching sequence diagram according to the embodiment of the present invention in the configuration of FIG. 1;

FIG. 10 is a gateway switching sequence diagram according to the embodiment of the present invention in the configuration of FIG. 2;

FIG. 11 is a gateway switching sequence diagram according to the embodiment of the present invention in the configuration of FIG. 3;

FIG. 12 is a specific example of a gateway switching sequence according to the present invention.

FIG. 13 is a sequence diagram when communication between a terminal and a server is performed during negotiation between gateways.

FIG. 14 is a sequence diagram showing a stop timing of a gateway connected to a plurality of terminals.

FIG. 15 is a sequence diagram in a case where a switch rejection is received in negotiation with a switching destination gateway and connection switching is performed with another gateway.

FIG. 16 is a sequence diagram when the switching destination gateway has no terminal accommodation capacity.

FIG. 17 is a sequence diagram when a terminal application displays that the gateway is being switched.

FIG. 18 is a gateway switching sequence diagram according to the embodiment of the present invention in the configuration of FIG. 1;

FIG. 19 is a specific example of a gateway switching sequence according to the present invention.

FIG. 20 is a retransmission control sequence diagram of a gateway and a terminal according to the present invention.

FIG. 21 is a sequence diagram of transaction processing that has occurred after the gateway switching notification.

FIG. 22 is a sequence diagram of a transaction process in which data is not received in response to a request generated before a gateway switching notification.

FIG. 23 is a sequence diagram of a transaction process in which data is received in response to a request generated before a gateway switching notification.

FIG. 24 is a gateway switching sequence diagram according to the fifth embodiment of the present invention.

FIG. 25 is a sequence diagram of a transaction process that has occurred after the gateway switching notification in the gateway switching according to the fifth embodiment of the present invention.

FIG. 26 is a sequence diagram of a transaction process in which data is not received in response to a request generated before a gateway switching notification in the gateway switching according to the fifth embodiment of the present invention.

FIG. 27 is a sequence diagram of a transaction process in which data is received in response to a request generated before a gateway switching notification in gateway switching according to the fifth embodiment of the present invention.

[Explanation of symbols]

 1, 14, 15, 17 Wireless terminal 2, 10 Wireless base station 3 Public network 4, 5, 16 Gateway according to the present invention 6, 9 Server 7, 8 Information for executing terminal application 11, 12 Conventional gateway 13 Gateway Connection means 14 Gateway and server connection means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 11/00 303 H04L 13/00 307A H04Q 7/04 D Matsushita Electric Information System Nagoya Research Laboratories, 2-6-1, Sakae-ku, 5th Floor Annex Hiroshi Ozaki 2-6-1, Sakae, Naka-ku, Nagoya-shi, Aichi 5th Floor, Shirakawa Building Annex Matsushita Electric Information System Nagoya Laboratory

Claims (43)

[Claims] 1. A communication system for establishing communication between a wireless information terminal and a server via a gateway, wherein the gateway informs the wireless information terminal of the occurrence of gateway switching when a gateway switching instruction is issued. A communication system comprising a notification unit. 2. A communication system for establishing communication between a wireless information terminal and a server via a gateway, wherein: when a gateway is instructed to switch, the gateway is switched, and the gateway is switched through the switching destination gateway. Information notifying means for notifying information necessary for communication with all the servers, to the wireless information terminal: receiving information necessary for communicating with the server via the above-mentioned switching destination gateway from the switching source gateway; A communication activation unit for executing an activation procedure of communication with a gateway to be switched to. 3. A communication system for establishing communication between a wireless information terminal and a server via a gateway, comprising: a gateway: a gateway in a state in which a switching source gateway relays communication between the wireless information terminal and the server; And information notification means for notifying the wireless information terminal of information necessary for communication between the wireless information terminal and the server via the switching destination gateway when the switching instruction of the wireless information terminal is provided. Start-up means for receiving information necessary for communicating with the server via the gateway from the switching source gateway, interrupting communication with the switching source gateway, and executing a procedure for restarting communication with the switching destination gateway A communication system comprising: 4. When the incomplete transaction remains during the process of interrupting the communication with the switching source gateway, the switching source gateway sends the switching destination gateway information on the response destination to the request from the terminal in the restart procedure. The communication system according to claim 3, further comprising the information exchanging means for notifying in advance. 5. The incomplete transaction is a request from the wireless information terminal to the server, which is generated after a switching notification is issued from the switching source gateway to the wireless information terminal, and is not received by the server. Item 5. A communication system according to item 4. 6. The incomplete transaction is executed by the switching source gateway in response to a request arriving at the server from the wireless terminal that occurred before the switching notification was issued from the switching source gateway to the wireless information terminal. 5. The case where ACK is returned to the wireless information terminal.
A communication system according to claim 1. 7. The incomplete transaction is a request from the wireless information terminal to the server generated before the switching information is issued from the gateway of the switching source to the wireless information terminal, and a response to the request from the switching source at the time of the interruption is received. The communication system according to claim 4, wherein the communication system arrives at the gateway and has not arrived at the terminal. 8. A gateway used in a communication system for relaying communication between a wireless information terminal and a server providing a service to the wireless information terminal, wherein when a gateway switching instruction is issued, the gateway switching to the wireless information terminal is performed. An information notifying means for notifying occurrence, and a gateway. 9. A gateway used in a communication system that relays communication between a wireless information terminal and a server that provides a service to the wireless information terminal. A gateway comprising information notification means for notifying information necessary for communication with a server via the gateway. 10. A gateway used in a communication system that relays communication between a wireless information terminal and a server that provides a service to the wireless information terminal, wherein the gateway is used for communication between the wireless information terminal and a gateway to be switched to. A gateway on the switching source side, comprising an information notifying unit for notifying information. 11. The server according to claim 10, wherein at the time of the interruption processing of the communication with the wireless information terminal, if an incomplete transaction remains, the server notifies a server of a response destination to a request from the terminal before the restart procedure. gateway 12. The wireless communication terminal according to claim 11, wherein the incomplete transaction is a request from the wireless information terminal to the server, which is generated after the switching notification is issued to the wireless information terminal, and is based on a request that has not arrived at the server. gateway. 13. The case where the incomplete transaction is a request that has occurred before the switching notification is issued to the wireless information terminal and has arrived at the server from the wireless terminal, and an ACK has been issued to the wireless information terminal. The gateway according to claim 11, which is: 14. The uncompleted transaction is a request from the wireless terminal to the server that occurred before the switching notification was issued to the wireless information terminal, and the response from the server has not arrived at the terminal at the time of the interruption. The gateway of claim 11. 15. A wireless information terminal that establishes communication with a server that provides a service via a gateway, wherein the switching to the gateway is performed in a state where the switching source gateway relays the communication between the wireless information terminal and the server. When instructed, information required to communicate with the server via the switching destination gateway is received together with the switching notification from the switching source gateway, and communication with the switching source gateway is interrupted. A wireless information terminal comprising restart activation means for executing a restart procedure of communication with a switching destination gateway based on the restart information. 16. A communication system for establishing communication between a wireless information terminal and a server providing a service to the wireless information terminal via a gateway, comprising: a gateway: a switching source gateway communicating between the wireless information terminal and the server; When the gateway is instructed to switch between the wireless information terminals and the server, information required for the wireless information terminal and server to communicate via the switching destination gateway is exchanged between the switching source and switching destination gateways Information exchange means that can be used,
An information notifying unit for notifying information necessary for communication with the switching destination gateway, and receiving information necessary for communicating with the server via the switching destination gateway from the switching source gateway to the wireless information terminal. And a restart activation means for interrupting communication with the switching source gateway and executing a procedure for restarting communication with the switching destination gateway. 17. When the information about the communication state of the wireless communication terminal and the gateway of the switching source differs before and after the information exchange between the gateway of the switching source and the gateway of the switching destination by the information exchanging means, the communication status information does not match. When the wireless information terminal establishes communication connection with the switching destination gateway, information for supplementing the matching is provided from the wireless information terminal to the switching destination gateway. Item 16
A communication system according to claim 1. 18. The communication system according to claim 17, wherein the inconsistency is generated based on communication between the wireless information terminal and the gateway device of the switching source that occurred during the information exchange. 19. In the process of interrupting the communication with the switching source gateway, when there is an uncompleted transaction, the switching source gateway notifies the switching destination gateway of information on the uncompleted transaction before the restart procedure. 17. The communication system according to claim 16, further comprising the information exchange unit that performs the information exchange. 20. The incomplete transaction according to a request from a wireless information terminal to a server, which is generated after a switching notification is issued from a gateway at a switching source to a wireless information terminal, and based on a request that has not arrived at the server. The communication system according to claim 19, wherein the communication system has occurred. 21. The incomplete transaction corresponds to a request from a wireless terminal to a server generated before a switching notification is issued from the switching source gateway to the wireless information terminal, and after the interruption, the switching source gateway from the server. 20. The communication system according to claim 19, based on a response to 22. The incomplete transaction is a request from the wireless information terminal to the server that occurred before the switching notification was issued from the switching source gateway to the wireless information terminal. 20. The communication system of claim 19, based on a response to the original gateway. 23. The information sent from the switching source gateway to the switching destination gateway includes the capability of the terminal, and when the capability of the terminal cannot be accommodated by the switching destination gateway, the capability that can be provided to the terminal is determined by the switching source gateway. 17. The communication system according to claim 16, comprising the information exchange means for notifying a gateway. 24. The information notifying means for notifying a terminal of the capability of the switching destination gateway together with the switching notification, and a radio for determining whether or not to resume communication with the switching destination gateway based on the capability. 24. The communication system according to claim 23, further comprising: a determination unit on an information terminal side. 25. A switching-source gateway which determines whether communication with a terminal is possible based on the capability of the switching-destination gateway, and stops the switching-source gateway when the communication is not possible.
3. The communication system according to item 3. 26. The communication system according to claim 16, further comprising the information exchange means for exchanging information with another candidate switching destination gateway when the switching is rejected by the first candidate switching destination gateway. 27. A gateway used in a communication system that relays communication between a wireless information terminal and a server that provides a service to the wireless information terminal, wherein the gateway relays communication between the wireless information terminal and the server.
Information exchange means for enabling exchange of information required for communication between the wireless information terminal and the server via the switching destination gateway between the switching destination gateway when a gateway switching instruction is issued; An information notifying unit for notifying an information terminal of information necessary for communication with a gateway to be switched to, a gateway on the switching source side. 28. In the process of interrupting communication with the wireless information terminal, when an uncompleted transaction remains, the switching destination gateway is notified of information on the uncompleted transaction before the restart procedure by the wireless information terminal. 27. The switching source side provided with information exchange means.
Gateway described in 29. The wireless communication terminal according to claim 28, wherein the incomplete transaction is a request from the wireless information terminal to the server, which is generated after the switching notification is issued to the wireless information terminal, and is based on a request that has not arrived at the server. gateway. 30. The incomplete transaction responds to a request from the wireless terminal to the server that occurred before the switching notification was issued to the wireless information terminal, and the server responded to the switching source gateway after the interruption. 29. The gateway of claim 28, based on case. 31. The incomplete transaction is a request from the wireless terminal to the server generated before the switching notification is issued to the wireless information terminal, and a response to the switching source gateway that has not arrived at the terminal at the time of the interruption. 29. The gateway of claim 28 based on 32. A gateway used in a communication system that relays communication between a wireless information terminal and a server that provides a service to the wireless information terminal, wherein the gateway at the switching source relays communication between the wireless information terminal and the server. And information exchange means for enabling exchange of information necessary for communication between the wireless information terminal and the server between the gateway and the switching source gateway when a gateway switching instruction is issued in a state where the gateway is switched. The gateway to switch to. 33. A wireless information terminal that establishes communication with a server providing a service via a gateway, wherein the switching to the gateway is performed in a state where the gateway of the switching is relaying the communication between the wireless information terminal and the server. When instructed, information required to communicate with the server via the switching destination gateway is received together with the switching notification from the switching source gateway, and communication with the switching source gateway is interrupted. A wireless information terminal comprising restart activation means for executing a restart procedure of communication with a switching destination gateway based on the restart information. 34. The wireless information terminal according to claim 33, further comprising display means for displaying a message indicating that the interruption is being performed during the period from the interruption to the resumption. 35. Instead of the switching notification, upon receiving a stop notification of the switching source gateway when the switching destination gateway refuses communication with the terminal,
34. The wireless information terminal according to claim 33, further comprising display means for displaying the stop notification. 36. When there is an inconsistency in the notification state with the switching source gateway before and after the necessary information exchange after the switching between the switching source gateway and the switching destination gateway, the information to compensate for the inconsistency is restarted. The wireless information terminal according to claim 33, wherein the wireless information terminal notifies the switching destination gateway in the procedure. 37. The communication system according to claim 1, wherein a common server is used by the switching source gateway and the switching destination gateway. 38. The communication system according to claim 1, wherein said switching source gateway and said switching destination gateway use different servers having equivalent contents. 39. The communication system according to claim 1, wherein the switching source gateway and the switching destination gateway each include different servers having equivalent contents. 40. A communication method for establishing communication between a wireless information terminal and a server via a gateway, wherein when a gateway switching instruction is issued, the wireless information terminal is notified of the occurrence of gateway switching. Communication method to be used. 41. A communication method for establishing communication between a wireless information terminal and a server via a gateway, wherein when a gateway switching instruction is issued, gateway switching occurs and the server via the switching destination gateway. Notifying information necessary for communication with the gateway, and receiving information required for communicating with the server via the switching destination gateway from the switching source gateway, and starting communication with the switching destination gateway. Executing the communication method. 42. A communication method for establishing communication between a wireless information terminal and a server via a gateway, wherein the switching source gateway relays communication between the wireless information terminal and the server, and issues a gateway switching instruction. Notifying the wireless information terminal of information necessary for communication between the wireless information terminal and the server via the switching destination gateway; and communicating with the server via the switching destination gateway. Receiving the necessary information from the switching source gateway, interrupting the communication with the switching source gateway, and executing a procedure for resuming the communication with the switching destination gateway by the wireless information terminal. Communication method. 43. A communication method for establishing communication between a wireless information terminal and a server providing a service to the wireless information terminal via a gateway, wherein the switching source gateway relays communication between the wireless information terminal and the server. The wireless information terminal and the server notify the switching destination gateway of information necessary for communication between the wireless information terminal and the server via the switching destination gateway when the gateway switching instruction is issued in the state where the switching is performed. And from the switching gateway to the wireless information terminal,
Notifying the information necessary for communication with the switching destination gateway; and further, communicating with the switching source gateway while receiving the information necessary for communicating with the server via the switching destination gateway. Suspending and resuming the communication procedure with the switching destination gateway by the wireless information terminal.