JP3672534B2 - Routing control method, routing control device, recording medium, and control program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides communication in which at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network The present invention relates to a routing control method and a routing control device used for controlling each node where a proxy is arranged in a system.
[0002]
[Prior art]
When a user wants to stop using an application (program) with which communication is performed and try to perform communication with another application, it is necessary to interrupt communication and then restart communication with another application. However, in this case, since communication is disconnected, it is necessary to start the communication procedure with the partner application from the beginning. That is, the communication service for a certain application cannot be switched to another application from the middle.
[0003]
For example, a mobile terminal such as a notebook personal computer or PDA can be carried so that it may be used in various places, and may be used while moving. When such a mobile terminal is used online, for example, a communication adapter corresponding to Ethernet (registered trademark), local wireless LAN (Local Area Network), public wireless communication (for example, PHS (Personal Handy-phone System)), etc. It is necessary to connect the mobile terminal to the network using.
[0004]
In various places where a mobile terminal is used, it is possible to connect the mobile terminal to a network using one or more communication media. If a plurality of communication adapters corresponding to a plurality of types of communication media are installed in advance, one mobile terminal can be connected to a network at various locations by switching the communication method as necessary.
[0005]
When a plurality of terminals actually communicate with each other using a server application and a client application, first, the terminal hardware is connected to the network, and a communication connection is established between the server application that provides the service and the client application that uses the service. Need to be established.
Also, in order to allow communication to continue even if communication is temporarily interrupted due to a failure, for example, a communication path is constructed so that a relay device called a proxy is interposed between the server application and the client application. Is common.
[0006]
In such a conventional communication system, the communication path is determined when communication between the server application and the client application is started. Therefore, the combination of the server application, client application, and proxy to be used cannot be changed during communication.
When changing the server application, the client application, or the proxy, it is necessary to once terminate communication, release the communication connection, and reconnect each communication connection between the server application and the client application.
[0007]
However, when the mobile terminal communicates while moving, the positional relationship among the server application, the client application, and the proxy changes with movement, so that a redundant communication path may be formed. For example, there is a case where communication is continued by relaying an unnecessary proxy.
Also, for example, when a failure occurs in a communicating terminal, communication is temporarily terminated, the communication connection is released, and the communication path is changed so that the application or proxy function of the failed terminal is replaced with another terminal. It is necessary to rebuild and start communication from the beginning.
[0008]
Further, for example, when switching a terminal used by a user from a mobile terminal having a small screen to a fixed terminal having a large screen (for example, a desktop personal computer), the communication of the mobile terminal is terminated, the communication connection is released, and the fixed terminal It is necessary to construct a new communication path using and to start communication from the beginning.
By the way, communication path determination (routing) in an IP (Internet Protocol) network is generally conscious of the configuration of a physical network.
[0009]
Therefore, a hierarchical structure is formed such as routing within a domain, which is a cluster of several local networks, and routing between domains. Then, it is possible to limit the capacity of the routing table on the assumption that the hierarchical structure is maintained.
[0010]
On the other hand, an ad hoc network is known as a flat network having no hierarchical structure. In an ad hoc network, a network is configured by directly communicating between wireless nodes.
In an ad hoc network, since wireless communication is used, broadcast communication can be easily performed, and resource information on the network can be suppressed to a minimum when notifying neighboring hosts of information necessary for routing.
[0011]
[Problems to be solved by the invention]
In the conventional routing in the IP network, it is inevitable that the routing functions are concentrated on some nodes in the network in order to maintain and manage the hierarchical structure.
In addition, the routing method adopted in the ad hoc network greatly reduces the efficiency in a network in which broadcast communication to the neighborhood cannot be performed with minimum resource consumption. Therefore, the ad hoc network routing cannot be used in the IP network.
[0012]
In the conventional routing control, since the lower layer is a link layer that does not transfer outside a specific data link, communication between nodes in the network is not possible unless an upper layer routing protocol is provided.
Many companies and institutions have a firewall (network protection wall) that blocks communication at the network layer (IP level), but end-to-end applications are completed with communication functions provided at the network layer. Communication cannot operate beyond this firewall.
[0013]
The present invention is a routing capable of reducing resource consumption and improving efficiency on the assumption that connectivity between nodes in a lower network is ensured when routing is performed on a flat virtual network having no hierarchical structure. An object of the present invention is to provide a control method and a routing control device, and to enable communication beyond a firewall by using a communication network composed of proxies.
[0014]
[Means for Solving the Problems]
According to a first aspect of the present invention, at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. A routing control method used for controlling each node in which a proxy is arranged in a communication system, which manages each application program, a service address that identifies each proxy, and a session representing each communication, and each application The location of the program and the location of each proxy are managed as a resource table, the first service address representing the destination application program, and the other hops of the own proxy on the communication path connected to the destination When the correspondence relationship with the second service address representing the proxy is managed as a proxy routing table, the network address of the communication device existing in each node is managed as a location table, and the information managed in the own node is updated Or, when it is necessary to search for information that does not exist in its own node, a message is sent to the other node managed in the resource table or location table, and the local node requests a search from another node If the requested information exists in the local node, the search result is sent to the message originator, and the local node receives a request for a search from another node and is requested. If the information does not exist on the local node or if a message indicating information update is received If the number of hops from the message source does not exceed the limit value, the content of the received message is transferred to another node managed in the resource table or the location table. And
[0015]
In claim 1, since the correspondence relation between the destination application program and the other proxy of the next hop can be grasped by referring to the proxy routing table, between the other proxy of the next hop and the destination application program Even when the network configuration changes, it is possible to automatically recognize the proxy to be reconnected and continue the service.
[0016]
Further, the location of each application program and the location of each proxy can be recognized based on the resource table, and the network address of the communication device existing in each node can be recognized based on the location table.
Further, when information managed in each table of the own node is updated due to a change in the network, the change in the network can be grasped in each node by notifying other nodes of the change as a message.
[0017]
In addition, when it is necessary to search for information that does not exist in the own node, information managed by the other node can be used by sending a message requesting the search to the other node.
On the other hand, when a large number of messages are sent over the network due to changes in the network or the like, the network utilization efficiency decreases. Further, the processing capacity of each node and the amount of information that can be stored in a table on the node are limited.
[0018]
However, in claim 1, since the number of hops from the transmission source when a message received by each node is transferred is suppressed to the limit value, the amount of messages transmitted on the network can be suppressed and added to the table of each node. The amount of information that is used can also be suppressed.
According to claim 2, in the routing control method according to claim 1, when a plurality of the same messages transmitted by other nodes are received, only one message is processed, and the remaining messages are ignored. It is characterized by.
[0019]
As for a message transmitted on the network, the same message may reach the same node a plurality of times via a plurality of routes. According to the second aspect of the present invention, when a plurality of the same messages are received, only one message is processed, so that the processing amount for the message at each node is reduced and the useless messages transmitted on the network are reduced. Can do.
[0020]
According to a third aspect of the present invention, in the routing control method of the first aspect, the number of transfer destination nodes when each node transfers a received message to another node is limited to a predetermined number.
According to the third aspect of the present invention, since the number of transfer destination nodes of messages sent from each node is suppressed, the total number of messages appearing on the network can be reduced, and the network utilization efficiency can be improved.
[0021]
According to a fourth aspect of the present invention, in the routing control method of the first aspect, history information regarding a node through which the message transferred between a plurality of nodes has passed and a node to which the same message has already been transmitted is included in the message. When a received message is transferred, the history information is examined and nodes included therein are excluded from transfer destination nodes.
[0022]
According to the fourth aspect of the present invention, control is performed so that the same message is not sent to the node to which the message has already passed and the node to which the same message has already been transmitted based on the history information, so that the same message repeatedly reaches the same node. Network efficiency can be improved.
In the routing control method according to claim 1, in the routing control method according to claim 1, for each of the other nodes managed by the own node, the communication frequency between the own node and the other node and the similarity of the managed information are determined. When information representing at least one is managed and a message received by each node is transferred, a node having a high communication frequency or a node having a high similarity is preferentially selected as a transfer destination.
[0023]
In claim 5, since a node with high communication frequency or a node with high similarity is preferentially selected as a transfer destination, when searching for information, a node with a high probability that the target information exists Search can be requested and search can be performed efficiently. Further, when updating information, a message can be transmitted to a node having a high probability of requiring the information.
[0024]
Therefore, it is possible to search for information necessary for routing and update information by sending relatively few messages to the network.
Claim 6 is the routing control method according to claim 1, wherein, for each of the other nodes managed by the own node, information on importance indicating the communication frequency between the own node and the other node is managed. When the capacity of the information managed in each table exceeds a limit value, the information regarding the node having the low importance is preferentially deleted from the table.
[0025]
In claim 6, when the capacity of the information managed in each table exceeds the limit value, the information regarding the node having a low communication frequency between the nodes is preferentially deleted from the table. Can be left in the table, and efficient routing is possible even for a node having a small storage capacity of the table.
According to a seventh aspect of the present invention, at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. In a communication system, a routing control device used for controlling each node in which a proxy is arranged, and a session management means for managing each application program, a service address for identifying each proxy, and a session representing each communication A resource table for managing the location of each application program and the location of each proxy, a first service address representing the destination application program, and the proxy of the local proxy on the communication path connected to the destination Managed by the own node, a proxy routing table that manages the correspondence with the second service address representing another proxy located at the hop, a location table that manages the network address of the communication device that exists in each node, and A message sending means for sending a message to another node managed in the resource table or the location table when the information is updated or when it is necessary to search for information that does not exist in the own node; When the local node receives a message requesting a search from another node and the requested information exists in the local node, a search result transmitting means for transmitting the search result to the message source, and the local node A message requesting a search from another node is received and the requested information is If the message does not exist or if a message indicating information update is received, the content of the received message is managed in the resource table or location table if the number of hops from the message source does not exceed the limit value And a message transfer means for transferring the message to another node.
[0026]
By using the routing control device of claim 7, the routing control method of claim 1 can be realized.
According to an eighth aspect of the present invention, in the routing control device according to the seventh aspect, the search result transmitting unit and the message transfer unit process only one message when a plurality of the same messages transmitted from other nodes are received. And the rest of the message is ignored.
[0027]
By using the routing control device of claim 8, the routing control method of claim 2 can be realized.
According to a ninth aspect of the present invention, in the routing control device according to the seventh aspect, there is further provided a transfer destination node number limiting means for limiting the number of transfer destination nodes to a predetermined number when each node transfers the received message to another node. It is characterized by that.
[0028]
By using the routing control device of claim 9, the routing control method of claim 3 can be realized.
In the routing control device according to claim 7, when the history information of the passed node is included in the message transferred between a plurality of nodes, the message received by each node is transferred. A history identifying means for examining the history information and excluding nodes included in the history information from the transfer destination node is further provided.
[0029]
By using the routing control device of claim 10, the routing control method of claim 4 can be realized.
Claim 11 is the routing control device of claim 7, wherein for each of the other nodes managed by the own node, the communication frequency between the own node and the other node and the similarity of the information managed A communication frequency management means for managing information representing at least one and a transfer destination selection for preferentially selecting a node having a high communication frequency or a node having a high similarity when transferring a message received by each node. And a means.
[0030]
By using the routing control device of claim 11, the routing control method of claim 5 can be realized.
Claim 12 is the routing control device according to claim 7, wherein, for each of the other nodes managed by the own node, importance information for managing the communication frequency between the own node and the other node is managed. And a table information deleting unit that preferentially deletes information related to the low importance node from the table when the capacity of information managed in each table exceeds a limit value. It is characterized by that.
[0031]
By using the routing control device of claim 12, the routing control method of claim 6 can be realized.
According to a thirteenth aspect, at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. A recording medium recorded with a computer-executable control program for routing control of each node where a proxy is arranged, applied to a communication system, wherein each control program includes each application program and each proxy. Represents a service address to be identified, a procedure for managing a session representing each communication, a procedure for managing the location of each application program and the location of each proxy as a resource table, and a destination application program A procedure for managing a correspondence relationship between one service address and a second service address representing another proxy located at the next hop of the local proxy on a communication path connected to the destination as a proxy routing table; The procedure for managing the network address of the communication device existing in the node as a location table, and when the information managed in the own node is updated, or when it is necessary to search for information that does not exist in the own node, When sending a message to another node managed in the resource table or location table and when the local node receives a message requesting a search from another node, and the requested information exists in the local node Includes a procedure for sending search results to the message originator and If a message requesting a search from a node is received and the requested information does not exist in the local node, or if a message indicating information update is received, the number of hops from the message source exceeds the limit value. If not, a procedure for transferring the content of the received message to another node managed by the resource table or the location table is provided.
[0032]
By executing the control program recorded on the recording medium of claim 13, the method of claim 1 can be implemented.
According to a fourteenth aspect of the present invention, at least one of an application program and a proxy that relays communication is provided in each communication device that configures a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. A control program that is applied to a communication system and that can be executed by a computer for routing control of each node in which a proxy is arranged, and represents each application program and a service address that identifies each proxy, and each communication A procedure for managing a session, a procedure for managing the location of each application program and the location of each proxy as a resource table, a first service address representing a destination application program, and a connection to the destination A procedure for managing, as a proxy routing table, a correspondence relationship with a second service address representing another proxy located at the next hop of the local proxy on a communication route, and a network address of a communication device existing in each node Other procedures managed in the resource table or location table when the information managed in the local node is updated, or when information that does not exist in the local node needs to be searched The procedure for sending a message to the other node, and when the local node receives a message requesting a search from another node and the requested information exists in the local node, the search result is sent to the message originator. And a message requesting a search from another node. If the requested information does not exist in the local node, or if a message indicating the update of information is received, the content of the received message is displayed if the number of hops from the message source does not exceed the limit. And a transfer procedure to another node managed by the resource table or the location table.
[0033]
By executing the control program of claim 14, the method of claim 1 can be implemented.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. This form corresponds to all the claims.
[0035]
In this form, the session management means, resource table, proxy routing table, location table, message transmission means, search result transmission means and message transfer means of claim 7 are the session management unit 502, resource table RST, proxy routing table PRT, respectively. , Location table LCT, step S316, step S306 and step S305 (S316).
[0036]
The transfer destination node number limiting means according to claim 9 corresponds to step S305 (S316). The history identifying means of claim 10 corresponds to step S305 (S316). The communication frequency management means of claim 11 corresponds to steps S324 to S327, and the transfer destination selection means of claim 11 corresponds to step S305 (S316). The importance level management means of claim 12 corresponds to steps S324 to S327, and the table information deletion means of claim 12 corresponds to step S322.
[0037]
Before entering into a characteristic description of the present invention, basic techniques required for implementing the present invention will be described.
(First basic technology)
This will be described with reference to FIGS.
FIG. 30 is a sequence diagram showing a control sequence when switching between a proxy and an application. FIG. 31 is a block diagram illustrating an example of a communication path when switching between a proxy and an application. FIG. 32 is a sequence diagram showing a control sequence when a proxy is added to a session. FIG. 33 is a block diagram illustrating an example of a communication path when a proxy is added to a session.
[0038]
FIG. 34 is a sequence diagram showing a control sequence for deleting a proxy from a session. FIG. 35 is a block diagram illustrating an example of a communication path when a proxy is deleted from a session. FIG. 36 is a sequence diagram showing a control sequence for replacing a proxy on a session. FIG. 37 is a block diagram illustrating an example of a communication path when a proxy on a session is replaced.
[0039]
FIG. 38 is a block diagram illustrating a configuration example of a communication system. FIG. 39 is a block diagram illustrating a configuration example of a mobile terminal. FIG. 40 is a schematic diagram illustrating an example of information held by the service management unit SR. FIG. 41 is a schematic diagram illustrating an example of information held by the position management unit LR. FIG. 42 is a schematic diagram illustrating an example of information held by the session management unit SM.
[0040]
FIG. 43 is a block diagram illustrating a configuration example of a communication system. FIG. 44 is a block diagram illustrating a configuration example of a network. FIG. 45 is a block diagram showing a movement model of nodes and services. FIG. 46 is a sequence diagram showing a procedure for updating position information when the terminal moves.
In this form, for example, a case where a communication system as shown in FIG. 38 is used is assumed. In the example of FIG. 38, three types of sub-networks 51, 52, and 53 are connected to each other via a wide area network.
[0041]
In the sub-network 51, a large number of terminals (55, 56) can be connected in a communicable state via a communication interface configured in accordance with the Ethernet (registered trademark) standard.
The sub network 52 constitutes a wireless LAN. Mobile terminals 59 and 60 having a wireless communication interface conforming to this standard can perform wireless communication with the base stations 57 and 58 and are connected to the sub-network 52 wirelessly. Of course, communication with the base stations 57 and 58 is not possible outside a specific communicable area.
[0042]
The sub-network 53 is a PHS network that is a public wireless communication system. In the example of FIG. 38, a mobile terminal 61, a fixed terminal 62, and a TAP (PIAFS terminal adapter) 63 are connected to the subnetwork 53, and base stations 64 and 65 are connected to the TAP 63. Mobile terminals 66 and 67 having a wireless communication interface configured in accordance with the PHS communication standard can perform wireless communication with the base stations 64 and 65. Of course, communication with the base stations 64 and 65 is not possible outside a specific communicable area.
[0043]
For example, when the mobile terminal 59 shown in FIG. 38 moves to the vicinity of the mobile terminal 55, the mobile terminal 59 may not be able to perform wireless communication with the base station 57. However, at that position, the mobile terminal 59 can be connected to the sub-network 51 by wire.
[0044]
In the case of a general system, when the network used for communication by the terminal is switched between the sub-networks 51, 52, and 53, it is necessary to once terminate communication of the application and reconstruct the communication path. It takes time and effort.
By using the technique described here, even when the network used by the terminal for communication is switched between the sub-networks 51, 52, and 53, the switching is automatically performed without terminating the communication of the application. It can be carried out.
[0045]
Further, for example, when the same application program exists in the mobile terminal 55 and the fixed terminal 56, the application on the fixed terminal 56 is in progress while one user is communicating using the application program on the mobile terminal 55. You can also switch to the program and continue to communicate.
Each terminal (mobile terminal in this example) used here is configured as shown in FIG. The mobile terminal in FIG. 39 includes an Ethernet (registered trademark) communication adapter 21 to enable connection to the subnetwork 51, and includes a wireless LAN adapter 22 to enable connection to the subnetwork 52. A PHS communication adapter 23 is provided to enable connection with the network 53.
[0046]
The mobile terminal shown in FIG. 39 includes a server application 11, a client application 12, a proxy 13, an agent 14, a link switching unit 15, links 16, 17, 18, a location management unit LR, a session management unit SM, and a service management unit as software 10. SR is provided.
The server application 11 is a program for providing a specific application service. The client application 12 is a program for using a service provided by the server for a specific application.
[0047]
The proxy 13 relays communication from a certain transmission source to a certain reception destination, and accumulates communication contents in its own storage device. For example, even if communication between the proxy 13 and the destination is temporarily disabled, the contents of communication input from the transmission source to the proxy 13 are accumulated in the proxy 13. When communication with the receiver is restored, the information stored in the proxy 13 can be transmitted to the receiver and communication can be continued.
[0048]
The proxy 13 in FIG. 39 can relay the communication of the server application 11 or the communication of the client application 12.
The link switching unit 15 switches the links 16, 17, and 18 used for communication with other terminals. The link 16 is connected to the Ethernet (registered trademark) communication adapter 21, the link 17 is connected to the wireless LAN adapter 22, and the link 18 is connected to the PHS communication adapter 23.
[0049]
When communicating using the link 16 and the Ethernet (registered trademark) communication adapter 21, communication is possible via the sub-network 51, and when communicating via the link 17 and the wireless LAN adapter 22, the sub-network 51 is communicated. Communication can be performed via the network 52, and communication can be performed via the sub-network 53 when the link 18 and the PHS communication adapter 23 are used.
[0050]
That is, the communication method can be switched by switching the links 16, 17, and 18 used by the link switching unit 15 to connect to any of the sub-networks 51, 52, and 53.
Each terminal that performs communication is assigned an IP (Internet Protocol) address. Further, when the terminal switches the communication method, the terminal moves on the network beyond the subnet boundary, which is an address allocation unit. Therefore, a new address is used every time switching is performed.
[0051]
The service management unit SR manages information on the types and functions of the server application 11, the client application 12, and the proxy 13 provided in each terminal.
[0052]
Actually, for example, the content shown in FIG. 40 is held in the service management unit SR. In the example of FIG. 40, the terminal A11 holds a server B11 as an application program and includes a proxy C11. The terminal A12 holds a server B12 as an application program and includes a proxy C12. Further, the terminal A13 holds a client B13 as an application program and includes a proxy C13.
[0053]
The location management unit LR manages the IP address for each terminal. The location management unit LR can manage the IP addresses of a large number of terminals as well as terminals equipped with the position management unit LR. However, in order to improve the efficiency of location management and to enable location management even for a terminal with few resources, the amount of movement of the terminal and the storage capacity relating to location management are also managed. Further, in order to limit the range of terminals to be managed, a plurality of terminals are divided into groups and managed.
[0054]
Actually, as shown in FIG. 41, for example, terminal identification name E10, group name E11, IP address E12, status (usability) E13 of each IP address, movement amount E14, storage capacity of LR and information on update time Is held for each terminal of a specific group managed by the.
Further, when the communication device is switched along with the movement of the terminal or the like, the IP address of the terminal changes. In this case, the content held by the location management unit LR is updated. At the same time, if there is a communication partner, a position information update command is transmitted to the communication partner. That is, the update procedure shown in FIG. 46 is executed.
[0055]
Further, when each terminal transmits a position information update command, the order in which the commands are transmitted is determined in consideration of a predetermined priority. For example, a high priority is given to a terminal with a small amount of movement such as a fixed terminal (desktop personal computer or the like) 56. Also, a high priority is given to a terminal having a large storage capacity (E15) of position information.
[0056]
Each group used for management of the location management unit LR can include a plurality of terminals existing in a range exceeding the boundary of the subnet. A plurality of groups can coexist in one subnet.
The terminal (X1) newly joining the group acquires its IP address and broadcasts a group search request in the subnetwork or transmits a group search request to a known specific terminal (X2). To do.
[0057]
Thereafter, when the terminal (X1) receives a response from the terminal (X2) that has received the group search request, the terminal (X1) acquires group information from the content and selects a group to join.
The terminal (X1) transmits a registration request for the selected group to the terminal (X2). The terminal (X2) acquires the position information of the terminal (X1) that transmitted this registration request.
[0058]
Also, the terminal (X2) that has received the registration request transmits the information of the location management unit LR included therein to the terminal (X1), and adds the location information of the subscribed terminal (X1) to the contents of the location management unit LR. This completes the procedure for joining the group.
When searching for location information regarding each terminal, the location information is searched from information held by the location management unit LR included in the terminal itself. If the search cannot be performed, a search request is sent to an arbitrary terminal included in the information held by the location management unit LR. When a result is returned in response to this search request, the position information is added to the position management unit LR.
[0059]
When searching for terminals belonging to the same group in the subnet, a broadcast packet is transmitted, and location information is registered in the location management unit LR based on a response to the broadcast packet.
The location management unit LR includes the following functions.
(1) IP address change due to movement of terminal location
(2) IP address status change due to node disconnection, line disconnection, failure, etc.
(3) Notification of change to agent 14
(4) Joining and leaving the group
(5) Transmission / reception of position information to / from the position management unit LR of the node in the group
The session management unit SM in FIG. 39 manages the entire communication path as a session for each communication. For example, in FIG. 44, communication can be performed between the application 101 and the application 102 using the session 103. In this case, the session 103 includes proxies 104, 105, and 106.
[0060]
The session 103 uses communication connections 107, 108, 109 and 110. A communication connection 107 is a communication path established between the application 102 and the proxy 104. The communication connection 108 is a communication path established between the proxies 104 and 105. The communication connection 109 is a communication path established between the proxies 105 and 106. The communication connection 110 is a communication path established between the application 101 and the proxy 106.
[0061]
The actual session management unit SM holds information G11 to G18 as shown in FIG. Information G11 is an identifier for distinguishing a plurality of sessions. The information G12 represents the name of the node (terminal) where the server application to be used exists. Information G13 represents a port number given to the server application to be used.
[0062]
Information G14 represents the name of the node where the client application to be used exists. Information G15 represents a port number given to the client application to be used. Information G16 represents the name of the node where the proxy to be used exists. Information G17 represents the port number given to the proxy to be used. When a communication path of one session is configured to relay a plurality of proxies, each node name, port number, and connection state of the plurality of proxies to be used are one session ID (G11 ) And stored in the session management unit SM.
[0063]
Functions performed by the session management unit SM include addition of a proxy to each session, deletion of a proxy, switching of a proxy, and communication with the session management unit SM existing in another terminal.
The agent (different from the application) 14 in FIG. 39 mediates various information held by the location management unit LR, the session management unit SM, and the service management unit SR, and determines the proxy based on comprehensive judgment of the information. 13 and the link switching unit 15 are controlled.
[0064]
For example, when it is desired to terminate a server application that currently provides a predetermined communication service while continuing a predetermined communication service, it is possible to search for an alternative server application of the same type using the service management unit SR. .
Further, since the location management unit LR holds the terminal identification name and its IP address, the location of the terminal where the switching destination server application exists can be specified. Furthermore, by performing processing described later using information on a specific session managed by the session management unit SM, it is possible to switch the server application and continue the communication service.
[0065]
The agent 14 instructs the link switching unit 15 to switch the link, and requests the proxy to restart the communication connection after the link is switched. The link switching unit 15 has functions such as connection to a new link, link disconnection, and routing management. Further, the proxy has a function of concealing the disconnection or change of the link under the connection (see FIG. 45).
[0066]
When a service is moved from a certain source to a certain destination, the status of the source service is changed from the session used for communication of the service to the service built on the destination application or proxy. It can be realized by transferring. The status of the service to be transferred includes the connection status of the applications and proxies constituting the session, the number of bytes of data being transmitted and received, the number of frames, and the like.
[0067]
For example, when a portable mobile terminal is used to receive and browse stream data from a specific server application via a wireless line and a network, a high-quality service can be received because the display capability of the terminal is low. Can not. However, if a user moves a service from a mobile terminal to a fixed terminal having a large screen, a high quality service can be received. Even in the case of such movement, the service can be continuously used.
[0068]
Further, when the same server application exists in a plurality of terminals, the communication path used for providing the service can be switched so as to switch the terminal and the application on the server side. It is also possible to improve the communication speed of the service by switching terminals.
A specific example of switching the communication path used for providing the service or switching the server application or the client application will be described below. Here, a communication system as shown in FIG. 43 is assumed.
[0069]
In FIG. 43, the functions of the mobile terminals 30 (1) to 30 (5) are simplified. Actually, each of the mobile terminals 30 (1) to 30 (5) has the same function as the mobile terminal shown in FIG.
However, the server application 11 is provided only in the mobile terminal 30 (1), and the client application 12 is provided only in the mobile terminals 30 (2) and 30 (3). Further, the mobile terminal 30 (5) is not provided with the session management unit SM. When the proxy 13 of the mobile terminal 30 (5) is used, control may be performed using the session management unit SM provided in the mobile terminal 30 other than the mobile terminal 30 (5).
[0070]
First, a case where proxy and application are switched will be described. Specifically, in the state before switching, the communication connection 201 is established between the server application 11 (1) of the mobile terminal 30 (1) and the proxy 13 (1) in FIG. 31, and the proxy 13 (1) and the proxy 13 The communication connection 202 is established between the client application 12 (2) and the proxy 13 (2), and the server application 11 (1) -proxy 13 (1) is established. It is assumed that the session is formed so as to pass through the communication path of the proxy 13 (2) -client application 12 (2).
[0071]
Here, instead of the client application 12 (2) on the mobile terminal 30 (2), the client application 12 (3) on the mobile terminal 30 (3) is used to continuously provide the service of the server application 11 (1). In the case of receiving, the control sequence shown in FIG. 30 is executed using the function of the session management unit SM (2). That is, the proxy 13 (2) is switched to the proxy 13 (3).
[0072]
The agent 14 of the terminal that manages the usage state of the user and the connection state between the terminals generates an application (AP) switching request as necessary (for example, according to a user instruction).
This switching request is notified to, for example, the session management unit SM (2). In this case, the session management unit SM (2) executes step S11 of FIG. That is, in order to switch to the switching destination proxy 13 (3) in which the communication connection 204 has been established with the switching destination client application 12 (3), an inquiry about switching is made to the proxy 13 (3). When making this inquiry, the session ID of the corresponding session and information on the connection status of the proxy are also transmitted as parameters from the session management unit SM (2) to the proxy 13 (3).
[0073]
This parameter also includes the file name of the file being relayed by the switching source proxy 13 (2) and the number of bytes that have been transferred (current transfer position on the file).
[0074]
Upon receiving the inquiry, the proxy 13 (3) activates necessary processes and the like based on the received parameters, and prepares for relaying communication in step S12. The proxy 13 (3) inherits the state of the switching source proxy 13 (2) based on the received parameters.
In this preparation, when the necessary application 12 (3) is not activated, the proxy 13 (3) activates the application 12 (3). If the communication connection 204 between the application 12 (3) and the proxy 13 (3) has not been established, the communication connection 204 is established.
[0075]
When the preparation is completed, in step S13, the proxy 13 (3) transmits a preparation completion notification to the session management unit SM (2).
When the session management unit SM (2) receives the preparation completion notification, in step S14, the session management unit SM (2) issues a switching request to the proxy 13 (1) that has established the communication connection 202 with the switching source proxy 13 (2). Send. This switching request includes a node name (G16) and a port number (G17) related to the proxy 13 (3) to be switched as parameters.
[0076]
When the proxy 13 (1) receives the switching request, the proxy 13 (1) uses the switching request parameter and the session ID to connect the proxy 13 (3) connection point (the IP address of the terminal and the port number of the proxy 13 (3)). ) Is established (S15).
When the communication connection 205 is established between the proxy 13 (3) and the proxy 13 (1), the communication connection 204 and the client application 12 (3) for the specific session determined by the session ID received when the communication connection 205 is established. ) Are associated (S16). Thus, the preparation of the proxy 13 (3) for relaying (accumulating and transferring) communication between the communication connection 205 and the communication connection 204 is completed.
[0077]
Further, the proxy 13 (1) switches all the communications that have been performed through the communication connection 202 to the communication connection 205 (S17). After the switching is completed, the proxy 13 (1) transmits a switching completion notification to the session management unit SM (2) (S18).
When the session management unit SM (2) receives the completion notification, the session management unit SM (2) updates the contents of the managed table (S19). In other words, the node name and port number of the client application 12 (3) and the proxy 13 (3) after switching and the connection relationship thereof are reflected with respect to a specific session determined by the session ID (session switched in this processing). Update the information as you do.
[0078]
Also, the session management unit SM (2) notifies the changed information to the other session management units SM (1), SM (3), SM (4) that manage the information of the changed session. (S21).
As a result of the above control sequence, as shown in FIG. 31, the service provided by the communication between the server application 11 (1) and the client application 12 (2) is the server application 11 (1) and the client application 12 ( The content of the session (communication path) is changed so that the communication with 3) is switched to.
[0079]
Next, a case where a proxy is added to a session will be described. Specifically, in the state before the addition, as shown in FIG. 33, a communication connection 211 is established between the server application 11 (1) and the proxy 13 (1), and the proxy 13 (1), 13 (2) A communication connection 212 is established between them, a communication connection 213 is established between the proxy 13 (2) and the client application 12 (2), and the two proxies 13 (1) and 13 (2) are connected to the server application 11 (1 ) And the client application 12 (2), the session is constructed so as to relay the communication.
[0080]
In this state, when adding the proxy 13 (3) between the proxy 13 (1) and the proxy 13 (2) while continuing communication, the function of the session management unit SM (2) is used. The control sequence shown in FIG. 32 is executed.
[0081]
The terminal agent 14 generates a proxy addition request as required (for example, according to a user instruction). This addition request is notified to, for example, the session management unit SM (2). In this case, the session management unit SM (2) executes step S31 of FIG.
That is, in order to make the proxy 13 (3) to be added prepare for addition, the session management unit SM (2) makes an additional inquiry. When making this inquiry, the session ID of the corresponding session and information on the connection status of the proxy are also transmitted as parameters from the session management unit SM (2) to the proxy 13 (3).
[0082]
This parameter includes the file name of the file relayed by the proxy 13 (2) and the number of bytes that have been transferred (current transfer position on the file).
Upon receiving the inquiry, the proxy 13 (3) activates necessary processes and the like based on the received parameters, and prepares for relaying communication in step S32. The proxy 13 (3) inherits the state of the proxy 13 (2) based on the received parameter. When the preparation is completed, in step S33, the proxy 13 (3) transmits a preparation completion notification to the session management unit SM (2).
[0083]
Upon receiving the preparation completion notification, the session management unit SM (2) transmits a switching request to the proxies 13 (1) and 13 (2) to be connected to the proxy 13 (3) to be added in steps S34 and S35. To do. This switching request includes the node name (G16) and port number (G17) related to the proxy 13 (3) to be added as parameters.
When the proxy 13 (1) and 13 (2) receive the switching request, the proxy 13 (3) connection point (the IP address of the terminal and the proxy 13 (3) Communication connection 214 or 215 is established for (port number) (S36, S37).
[0084]
When the communication connections 214 and 215 are established, the proxy 13 (3) associates the communication connection 214 and the communication connection 215 with respect to a specific session determined by the session ID received when these connections are established (S38). Thereby, the preparation of the proxy 13 (3) for relaying (accumulating and transferring) the communication between the communication connection 214 and the communication connection 215 is completed.
[0085]
On the other hand, the proxy 13 (1) switches all communications that have been performed through the communication connection 212 to the communication connection 214 (S41). After the switching is completed, the proxy 13 (1) transmits a switching completion notification to the session management unit SM (2) (S44).
Similarly, the proxy 13 (2) switches all communications that have been performed through the communication connection 212 to the communication connection 215 (S40). After the switching is completed, the proxy 13 (2) transmits a switching completion notification to the session management unit SM (2) (S42).
[0086]
When the session management unit SM (2) receives the completion notification, the session management unit SM (2) updates the contents of the managed table (S45). That is, for a specific session determined by the session ID (the session in which the proxy is added in this process), information is added to reflect the node name and port number of the added proxy 13 (3) and the connection relationship between the proxies. Update.
[0087]
Also, the session management unit SM (2) notifies the changed information to the other session management units SM (1), SM (3), SM (4) that manage the information of the changed session. (S46).
As a result of the above control sequence, as shown in FIG. 33, the communication between the server application 11 (1) and the client application 12 (2) is proxy 13 (1) -proxy 13 (3) -proxy 13 (2). The content of the session is changed so that it is relayed on the route.
[0088]
Next, the case where the proxy used until then is deleted from the session will be described. Specifically, in the state before the addition, as shown in FIG. 35, a communication connection 221 is established between the server application 11 (1) and the proxy 13 (1), and the proxy 13 (1), 13 (3) A communication connection 222 is established, a communication connection 223 is established between the proxies 13 (3) and 13 (2), and a communication connection 224 is established between the proxy 13 (2) and the client application 12 (2). The session is constructed so that the three proxies 13 (1), 13 (3), and 13 (2) relay the communication between the server application 11 (1) and the client application 12 (2). .
[0089]
When the proxy 13 (3) between the proxy 13 (1) and the proxy 13 (2) is deleted (excluded from the session) while communication is continued from that state, the function of the session management unit SM (2) Is used to execute the control sequence shown in FIG.
The terminal agent 14 generates a proxy deletion request as required (for example, according to a user instruction). This deletion request is notified to the session management unit SM (2), for example. In this case, the session management unit SM (2) executes processing in order from step S51 of FIG.
[0090]
The session management unit SM (2) sends a proxy 13 (1) and 13 (2) to each of the proxies 13 (1) and 13 (2) that establish communication connections 222 and 223 with the proxy 13 (3) to be deleted. A deletion request relating to 3) is transmitted (S51, S52).
Upon receiving the deletion request, the proxy 13 (2) establishes a communication connection 225 between the proxy 13 (2) and the proxy 13 (1) using the session ID (S53).
[0091]
Furthermore, the proxy 13 (2) switches all communications that have been performed through the communication connection 223 to the communication connection 225 (S54). After the switching is completed, the proxy 13 (2) transmits a switching completion notification to the session management unit SM (2) (S58). The communication connection 223 between the proxy 13 (2) and the proxy 13 (3) is disconnected by the proxy 13 (2) (S56).
[0092]
Similarly, the proxy 13 (1) switches all communications that have been performed through the communication connection 222 to the communication connection 225 (S55). After the switching is completed, the proxy 13 (1) transmits a switching completion notification to the session management unit SM (2) (S59). The communication connection 222 between the proxy 13 (1) and the proxy 13 (3) is disconnected by the proxy 13 (1) (S57).
[0093]
When the session management unit SM (2) receives the completion notification, the session management unit SM (2) updates the contents of the managed table (S60). That is, for a specific session determined by the session ID (the session in which the proxy is deleted in the current process), the information is updated to reflect the deletion result in the connection relationship between the proxies.
Also, the session management unit SM (2) notifies the changed information to the other session management units SM (1), SM (3), SM (4) that manage the information of the changed session. (S61).
[0094]
As a result of the above control sequence, as shown in FIG. 35, communication between the server application 11 (1) and the client application 12 (2) is relayed through the route of the proxy 13 (1) -proxy 13 (2). The contents of the session are changed.
Next, a case where a proxy used on a specific session is replaced with another proxy will be described. Specifically, in the state before the addition, as shown in FIG. 37, the communication connection 231 is established between the server application 11 (1) and the proxy 13 (1), and the proxy 13 (1), 13 (4) A communication connection 232 is established between them, a communication connection 233 is established between the proxies 13 (4) and 13 (2), and a communication connection 234 is established between the proxy 13 (2) and the client application 12 (2). The session is constructed so that the three proxies 13 (1), 13 (4), and 13 (2) relay the communication between the server application 11 (1) and the client application 12 (2). .
[0095]
In this state, when replacing the proxy 13 (4) that is used while continuing communication with the proxy 13 (5), the function shown in FIG. 36 is used by using the function of the session management unit SM (2). Run the sequence.
The terminal agent 14 generates a proxy replacement request as required (for example, according to a user instruction). This replacement request is notified to the session management unit SM (2), for example. In this case, the session management unit SM (2) executes step S71 of FIG.
[0096]
In other words, the session management unit SM (2) makes a replacement inquiry in order to prepare the replacement destination proxy 13 (5) for relaying. At the time of this inquiry, the session ID of the corresponding session and the connection state information of the proxy are also transmitted as parameters from the session management unit SM (2) to the proxy 13 (5).
This parameter includes the file name of the file being relayed by the proxy 13 (4) as the replacement source, and the number of bytes that have been transferred (current transfer position on the file).
[0097]
Upon receiving the inquiry, the proxy 13 (5) activates necessary processes and the like based on the received parameters, and prepares to relay communication in step S72. The proxy 13 (5) inherits the state of the replacement source proxy 13 (4) based on the received parameters. When the preparation is completed, in step S73, the proxy 13 (5) transmits a preparation completion notification to the session management unit SM (2).
[0098]
When the session management unit SM (2) receives the preparation completion notification, the proxy 13 (1), having established the communication connections 232, 233 with the replacement source proxy 13 (4) in steps S74 and S75. A switching request is transmitted to 13 (2). This switching request includes the node name (G16) and port number (G17) related to the proxy 13 (5) to be replaced as parameters.
[0099]
When the proxy 13 (1) and 13 (2) receive the switching request, the proxy 13 (5) connection point (the IP address of the terminal and the proxy 13 (3) Communication connection 235 or 236 is established for (port number) (S76, S77).
[0100]
When the communication connections 235 and 236 are established, the replacement proxy 13 (5) associates the communication connection 235 and the communication connection 236 with respect to a specific session determined by the session ID received when these connections are established (S78). ). Thereby, the preparation of the proxy 13 (5) for relaying (accumulating and transferring) the communication between the communication connection 235 and the communication connection 236 is completed.
[0101]
On the other hand, the proxy 13 (2) switches all communications that have been performed through the communication connection 233 to the communication connection 236 (S80). After the switching is completed, the proxy 13 (2) transmits a switching completion notification to the session management unit SM (2) (S82).
Similarly, the proxy 13 (1) switches all communications that have been performed through the communication connection 232 to the communication connection 235 (S81). After the switching is completed, the proxy 13 (1) transmits a switching completion notification to the session management unit SM (2) (S83).
[0102]
After the switching from the communication connections 232 and 233 to the communication connections 235 and 236 is completed, the unnecessary communication connections 232 and 233 are disconnected (S84, S85).
When the session management unit SM (2) receives the completion notification, the session management unit SM (2) updates the contents of the managed table (S86). That is, for a specific session determined by the session ID (the session in which proxy replacement is performed in the current process), information is updated so that the result of replacement is reflected in the connection relationship between proxies.
[0103]
Also, the session management unit SM (2) notifies the changed information to the other session management units SM (1), SM (3), SM (4) that manage the information of the changed session. (S87).
[0104]
As a result of the above control sequence, as shown in FIG. 37, the communication between the server application 11 (1) and the client application 12 (2) is proxy 13 (1) -proxy 13 (5) -proxy 13 (2). The content of the session is changed so that it is relayed on the route.
A unique session ID that is different for each session is assigned to the communication performed between the server application 11 and the client application 12. The proxy connection point represents a position on the network and a connection request receiving port. When TCP / IP is assumed as the protocol, the connection point is an IP address and a port number on which the proxy is listening.
[0105]
In addition, for example, when switching a communication connection in order to switch the communication path of a session, communication is temporarily disabled. However, at least one proxy included in the session accumulates communication contents transmitted by the application and performs communication. When it becomes possible, the stored information is transmitted to automatically perform communication recovery work. Therefore, even when the communication path is switched in the middle of communication, the user can continue the communication without performing any special operation.
[0106]
The outline of the functions described here can be expressed by a movement model shown in FIG. That is, the same service can be continuously provided to the same user even when the terminal used by the user moves and the communication method is switched or when the terminal used by the user is switched.
The service handled here means communication contents transmitted / received between applications through each session, a communication protocol (such as http) associated therewith, and an expression method (reproduction, browsing, etc.).
[0107]
When the service is moved, the service can be continued in the same state by transferring the service state from the movement source session indicated by the same session ID to the movement destination session.
[0108]
Each terminal (node) is mapped to a link layer address space as shown in FIG. Therefore, the movement of the node can be realized by changing the correspondence between the node and the address. Each terminal can have a plurality of communication devices, and each terminal can hold a unique address.
In order to evaluate the performance of the position management method in such a communication system, a simulation was performed using a computer. The simulation conditions are as follows.
[0109]
(1) Terminal movement interval: Among a large number of terminals constituting a group, (1/3) has an average movement time of 30 minutes, and the remaining (2/3) terminals have an average movement time of 10 minutes. .
(2) The communication standby time of the terminal is 20 minutes, and the communication time is 50 minutes.
(3) Storage capacity of location management unit LR: Among a large number of terminals, (1/3) LRs can hold location information of all terminals, and other (1/3) terminals have LRs of (1/2 ) Terminal position information can be held, and the remaining (1/3) terminal LRs can hold (1/4) terminal position information.
[0110]
(4) The number of location information update commands issued during 1200 minutes and the search success rate of the location management unit LR were measured for 400 trials. However, the first 100 minutes are excluded from the statistics.
(5) When the position management unit LR sends a position information update command, all position information held by itself is transmitted. In the LR on the receiving side, the position information that is selected and held by the time stamp of the position information is updated.
[0111]
(6) Two kinds of methods are evaluated for the priority order of the terminal when issuing the location information update command. In the “Method A” method, when the location management unit LR updates the location information held by itself, the location management unit LR issues a location information update command to all terminals. In the method of “Method B”, only the LR of the terminal having a storage capacity that can hold the position information of all terminals with a movement interval of 30 minutes issues a position information update command to all the terminals, and the remaining For the location management unit LR of the terminal, the location information update command is issued only to the terminal having a storage interval of 30 minutes and capable of holding the location information of all the terminals.
[0112]
In the “Method A” method, a location update command is issued to all terminals each time the location of each terminal is updated, so the communication volume increases, but excellent location management capability is obtained.
The simulation results are shown in FIGS. FIG. 47 shows the number of issued position information update instructions. 48 and 49 show the position search success rate. The location search success rate in FIG. 48 is a rate at which the location information of the other terminal is successfully acquired by the search of the location information held by the location management unit LR of the specific terminal and the search of the location management unit LR of other terminals. is there. Further, the location search success rate in FIG. 49 is a rate at which only the location information held by the location management unit LR of a specific terminal is searched to successfully acquire the location information of the counterpart terminal.
[0113]
47 and 48, it can be seen that “Method B” has a communication cost reduced (60 to 80% reduction) and “Position search capability” is also acceptable in comparison with “Method A”. . In addition, this effect becomes more prominent as the number of terminals constituting the group increases, and the difference in the location search success rate also decreases. Therefore, by limiting the terminals to which location information update commands are issued in consideration of the movement amount of each terminal and the storage capacity of the location management unit LR, the location management load of each terminal is shared and the communication volume is suppressed. can do.
[0114]
Further, as can be seen from FIG. 49, it is possible to correctly detect the positions of 25 to 45% of terminals without searching for position information existing in other terminals. Therefore, even when the terminal is temporarily disconnected from the network, it is possible to obtain a clue for reconnection to the network by searching only the position information held by its own position management unit LR. .
[0115]
(Second basic technology)
Next, a description will be given with reference to FIGS.
In this embodiment, since it is assumed that HTTP communication is performed, the browser 5 and the Web server 7 are used as applications.
In the example of FIG. 51, since the browsers 5 that operate as client applications are arranged in the nodes 8 (A) and 8 (B), the nodes 8 (A) and 8 (B) function as client nodes. Further, since the Web server 7 that operates as a server application is arranged in the node 8 (C), the node 8 (C) functions as a server node.
[0116]
In the example of FIG. 52, since the browsers 5 (A) and 5 (B) that operate as client applications are arranged in the node 8 (A), the node 8 (A) functions as a client node. In addition, since the Web server 7 that operates as a server application is arranged in the node 8 (C) of FIG. 52, the node 8 (C) functions as a server node.
[0117]
The operation of the example of FIG. 51 will be described.
First, a request is sent from the browser 5 (A) to the Web server 7 via the proxy 6 (A), 6 (B) (C11). The response of the Web server 7 to this request is transmitted to the browser 5 (A) via the proxies 6 (C) and 6 (A) (C12). At this time, a session is established. In addition, a session ID for distinguishing each session is assigned.
[0118]
Thereafter, the proxy 6 (C) accepts the service movement request (C13). In this case, the proxy 6 (C) interrupts communication (C14) and connects to the proxy 6 (B1) of the destination node 8 (B) (C15).
In this case, the destination proxy 6 (B1) starts the browser 5 (B) with the URL including the session ID of the corresponding session as an argument (C16).
[0119]
The activated browser 5 (B) connects to the proxy 6 (B2) using the URL specified at the time of activation (C17). Based on the session ID, the proxy 6 (B2) links the communication of the browser 5 (B) and the proxy 6 (C) of the node 8 (C) that is the server node to transfer data (C18).
In this way, the service moves through the client node while maintaining the continuity of the service.
[0120]
Next, the operation of the example of FIG. 52 will be described.
First, a request is made from the browser 5 (A) to the Web server 7 via the proxy 6 (A), 6 (C) (C21). The response of the Web server 7 is transferred to the browser 5 (A) via the proxies 6 (C) and 6 (A) (C22). At this time, a session is established. In addition, a session ID for distinguishing each session is assigned.
[0121]
Thereafter, the proxy 6 (A) accepts the service movement request (C23). In that case, the proxy 6 (A) starts the browser 5 (B) with the URL including the session ID of the corresponding session as an argument (C24).
The activated browser 5 (B) connects to the proxy 6 (B2) using the URL specified at the time of activation (C25). Based on the session ID, the proxy 6 (B2) links the communication of the browser 5 (B) and the proxy 6 (C) of the node 8 (C), which is the server node, to transfer data (C26).
[0122]
In this way, the service moves through the client node while maintaining the continuity of the service.
(Third basic technology)
Next, a description will be given with reference to FIGS.
FIG. 53 is a sequence diagram showing a simplified control sequence when a proxy is added to a session. FIG. 54 is a sequence diagram showing a simplified control sequence in the case of deleting a proxy from a session. FIG. 55 is a sequence diagram showing a simplified control sequence in the case of replacing a proxy on a session.
[0123]
This form is a modification of the first basic technique, and the contents of the control sequence are simplified as compared with the first embodiment. Also in this embodiment, it is assumed that a mobile terminal having a configuration as shown in FIG. 39 is used. However, the location management unit LR, service management unit SR, and link switching unit 15 shown in FIG. 39 are not necessarily required.
[0124]
The contents of the operations shown in FIGS. 53 to 55 are the same as those of the first basic technique, but the contents of the control in each figure will be described below.
First, the case of adding the proxy 13 (3) to the session as in the case of FIG. 33 will be described with reference to FIG.
In this example, in FIG. 33, communication connections are established in the order of the client application 12 (2), the proxy 13 (2), the proxy 13 (1), and the server application 11 (1), and the client application 12 (2) and the server application From the state in which a session is established with 11 (1), client application 12 (2), proxy 13 (2), proxy 13 (3), proxy 13 (1), and server application 11 (1) are in this order. It is assumed that a session connection between the client application 12 (2) and the server application 11 (1) is changed after a communication connection is established.
[0125]
That is, it represents an operation for adding another proxy 13 (3) between the proxy 13 (2) and the proxy 13 (1).
The agent software (14 in FIG. 39) controls commands and management related to the connection status between users or terminals. When the mobile terminal 30 (2) receives the proxy switching request from the agent software, the mobile terminal 30 (2) notifies the session management unit SM (2) of it.
[0126]
In this case, the session management unit SM (2) sets the name and connection point of the proxy 13 (3) as parameters for the proxies 13 (1) and 13 (2) connected to the added proxy 13 (3). The switching request is transmitted as (S34, S35). The proxy 13 (1), 13 (2) having received the switching request establishes a communication connection corresponding to the session identifier to the connection point of the proxy 13 (3) using the received parameter and the session identifier (ID). (S36, S37).
[0127]
After that, the proxy 13 (1) switches all the communication that has been performed through the communication connection with the proxy 13 (2) to the communication connection of the proxy 13 (3) (S40, S41).
Two communication connections are established in the added proxy 13 (3). The proxy 13 (3) associates two communication connections based on the session identifier received when the communication connection is established, and makes a state in which accumulation and transfer are possible.
[0128]
Next, the case of deleting the proxy 13 (3) from the session as in the case of FIG. 35 will be described with reference to FIG.
In this example, in FIG. 35, communication connections are established in the order of the client application 12 (2), proxy 13 (2), proxy 13 (3), proxy 13 (1), and server application 11 (1). From the state in which the session between (2) and the server application 11 (1) is established, the client application 12 (2), the proxy 13 (2), the proxy 13 (1), and the server application 11 (1) in this order. It is assumed that a communication connection is established and the session path is changed between the client application 12 (2) and the server application 11 (1).
[0129]
That is, it represents an operation for deleting the proxy 13 (3) from the session.
When the mobile terminal 30 (2) receives the proxy deletion request from the agent software, the mobile terminal 30 (2) notifies the session management unit SM (2) of it.
In this case, the session management unit SM (2) transmits a deletion request to the proxies 13 (1) and 13 (2) (S51, S52).
[0130]
When the proxy 13 (2) receives the deletion request, the proxy 13 (2) establishes a connection with the proxy 13 (1) using the session identifier. In addition, all the communication performed with the proxy 13 (3) is switched to the communication connection with the proxy 13 (1).
In addition, when the proxy 13 (1) receives the deletion request and establishes a communication connection from the proxy 13 (2), the proxy 13 (1) is performed through a communication connection with the proxy 13 (3). All the communication that has been made is switched to the communication connection with the proxy 13 (2).
[0131]
Next, the case where the proxy 13 (4), 13 (5) on the session is replaced as in the case of FIG. 37 will be described with reference to FIG.
In this example, in FIG. 37, the communication connection is established in the order of the client application 12 (2), the proxy 13 (2), the proxy 13 (4), the proxy 13 (1), and the server application 11 (1). From the state in which a session is established between (2) and the server application 11 (1), the client application 12 (2), the proxy 13 (2), the proxy 13 (5), the proxy 13 (1), and the server application It is assumed that the communication connection is established in the order of 11 (1) and the session path between the client application 12 (2) and the server application 11 (1) is changed.
[0132]
That is, it represents an operation for replacing the proxy 13 (4) on the session with the proxy 13 (5).
When the mobile terminal 30 (2) receives the proxy replacement request from the agent software, the mobile terminal 30 (2) notifies the session management unit SM (2) of it.
[0133]
In this case, the session management unit SM (2) transmits a switching request including the name of the proxy 13 (5) and the connection point as parameters to the proxies 13 (1) and 13 (2) having the communication connection. (S74, S75).
The proxy 13 (1), 13 (2) that has received the switching request establishes a communication connection corresponding to the session identifier with respect to the connection point of the proxy 13 (5) based on the received parameter.
[0134]
After that, the proxy 13 (1) switches all the communication performed in the communication connection with the proxy 13 (4) to the communication connection with the proxy 13 (5).
Similarly, the proxy 13 (2) switches all communication performed in the communication connection with the proxy 13 (4) to the communication connection with the proxy 13 (5).
[0135]
After the two communication connections are established, the proxy 13 (5) added to the session associates the two communication connections based on the session identifier received at the time of establishing the connection, and makes the state capable of storing and transferring.
(Example)
Next, specific examples including the features of the present invention will be described with reference to FIGS.
[0136]
FIG. 1 is a flowchart showing the operation of a proxy when a master and a shadow agent exist. FIG. 2 is a flowchart showing the operation of the master and shadow agent. FIG. 3 is a schematic diagram showing a configuration example of a service table used by the master and shadow agents. FIG. 4 is a sequence diagram illustrating an example of a shadow agent generation sequence. FIG. 5 is a sequence diagram showing an example of a shadow agent generation sequence.
[0137]
FIG. 6 is a sequence diagram showing an example of a message transfer sequence. FIG. 7 is a flowchart showing the proxy operation (1) for multicast. FIG. 8 is a flowchart showing the proxy operation (2) for multicast. FIG. 9 is a flowchart showing the proxy operation (1) for routing. FIG. 10 is a flowchart showing the proxy operation (2) for routing. FIG. 11 is a flowchart showing the proxy operation (3) for routing.
[0138]
FIG. 12 is a block diagram illustrating a configuration example of a network. FIG. 13 is a schematic diagram showing a configuration example (1) of a table in each node. FIG. 14 is a schematic diagram showing a configuration example (2) of a table in each node. FIG. 15 is a sequence diagram showing a basic communication sequence for providing a service. FIG. 16 is a block diagram showing an example of dynamic change of services.
[0139]
FIG. 17 is a sequence diagram showing a communication sequence when a master and a shadow agent exist. FIG. 18 is a sequence diagram showing a multicast communication sequence. FIG. 19 is a block diagram illustrating a configuration example of a communication path using a branch table. FIG. 20 is a flowchart showing the basic operation (1) of the proxy. FIG. 21 is a flowchart showing the basic operation (2) of the proxy. FIG. 22 is a flowchart showing the basic operation (3) of the proxy.
[0140]
FIG. 23 is a block diagram showing a functional configuration of the proxy. FIG. 24 is a block diagram showing connection management. FIG. 25 is a schematic diagram showing changes in connection management. FIG. 26 is a schematic diagram showing the configuration of each table on the node. FIG. 27 is a schematic diagram showing the configuration of an inter-proxy frame. FIG. 28 is a schematic diagram showing the configuration of the control command. FIG. 29 is a schematic diagram showing a configuration of an inter-proxy message.
[0141]
The network assumed here is a network that dynamically changes as described above, and there is a possibility that the node (communication device) that changes the network address or communicates while the service is being provided. .
Each term used in the following description is defined as follows.
The session ID is an identification name for uniquely identifying a session by a node, and is composed of a set of a node ID and an in-node number. Also, the session ID is different if the node is different even in the same session.
[0142]
The service address is a name that uniquely identifies the proxy and application.
The node ID is a name that uniquely identifies the node.
The network address is an address (IP address when TCP / IP is assumed) necessary for forming a communication connection between nodes.
A session represents communication configured between applications.
[0143]
A connection represents communication between proxies or between an application and a proxy.
The inter-proxy frame represents a data frame transmitted / received through a connection between proxies with a service.
The inter-proxy message represents a message exchanged between proxies for updating or searching the contents of the table.
[0144]
The basic configuration and operation of the communication system assumed here are as follows.
(1) A virtual network is configured on a physical network.
(2) Communication is performed between applications.
(3) The components are an application and a proxy. The application is configured as software on the node.
[0145]
(4) A session is configured by communication between applications, and communication between applications is relayed by a plurality of proxies.
(5) Applications and proxies constituting a session can be exchanged with other applications or proxies at any time, and the configuration can be freely changed. In addition, the session is maintained at that time.
[0146]
(6) Communication between proxies is managed by transmission / reception based on the sequence number, and when the connection (connection) between proxies has changed (in the case of CASE1, CASE2, and CASE3 in FIGS. 24 and 25), the communication has been received by that time. The requested sequence number is confirmed, and the sequence number to be sent next is requested from the proxy of the connection destination so that the sequence number does not become discontinuous, and is retransmitted. Thereby, the service is continued without data loss.
[0147]
In this embodiment, it is assumed that three types of movements CASE1, CASE2, and CASE3 shown in FIGS. 24 and 25 occur on the network.
As a specific network, a configuration as shown in FIG. 12 is assumed. In the example of FIG. 12, seven nodes are connected to each other. Different node IDs are assigned to the respective nodes.
[0148]
The applications and proxies provided in each node are as follows.
Node ID: 1001 Node: Application PA, Proxy PF
Node ID: 1002 Node: Application PC, Proxy PG
Node ID: 1003 Node: Application PB, Proxy PH
Node ID: 1004 Node: Application PD, Proxy PI
Node ID: 1005 Node: Application PL, Proxy PJ
Node ID: 1006 Node: Application PE
Node ID: 1007 Node: Proxy PK
Each node has various tables as shown in FIG. The outline of the contents of a typical table is as follows.
[0149]
1. Session table SST: Correspondence between session ID and service address.
2. Proxy routing table PRT: Correspondence between service address and next hop service address, and correspondence between master agent and shadow shadow agent.
3. Resource table RST: Correspondence between node ID and service address.
[0150]
4). Location table LCT: Correspondence between node ID and network address.
5. Branch table JCT: Correspondence between reception service address and transmission service address.
Each frame transferred between proxies is configured as shown in FIG. That is, a command, a transmission source node ID, a transmission source session ID, a transmission destination node ID, a transmission destination session ID, a transmission sequence number, a reception sequence number, a data length, and data are included in each frame.
[0151]
Further, there are a switching request and a disconnection request shown in FIG. 28 as control commands for controlling communication. These control commands are given to the proxy.
A message transferred between proxies is configured as shown in FIG. That is, the command, message length, hop count, search method, and parameters are included in the message.
[0152]
As shown in FIG. 23, each proxy includes a proxy control unit 501, a session management unit 502, a cache management unit 503, a connection management unit 504, a session table SST, a proxy routing table PRT, a resource table RST, A location table LCT and a branch table JCT are provided.
[0153]
The cache management unit 503 in FIG. 23 constructs a cache for each connection connection. Each cache stores unsent data until transmission is completed or a cache release command is received. Each cache exists and is managed for each connection connection connected to the proxy. In particular, in multicast communication, there may be a plurality of caches for each connection, and received data is distributed and transmitted to each cache according to the description of the branch table JCT. Since these caches operate independently, if there is a communication connection that cannot be transmitted, the cache assigned to that communication connection maintains the accumulated state, and the data stored in the cache of other communication connections that can be transmitted Is read and transmitted.
[0154]
Specific examples of contents of main tables provided in each node shown in the network of FIG. 12 are shown in FIGS. 13 and 14.
In order to realize the functions corresponding to each of the basic technologies described above, the proxy provided in each node executes the basic operations shown in FIGS. The basic operation of the proxy shown in FIGS. 20 to 22 will be described below.
[0155]
When the proxy receives the connection frame (see FIG. 27), the process proceeds from step S111 to step S112 in FIG. 20, and when the proxy receives a non-serviceable frame, the process proceeds from step S116 to S117.
When the session ID (SID) of the destination of the received connection frame is null (NULL), it is the first connection, so the process proceeds from step S112 to S113, and a unique session ID is generated on the node to which it belongs. In the next step S114, the session ID and the destination service address (SA) are added to the session table SST. In the next step S115, “connection processing” is executed. The contents of this “connection process” are shown in FIG.
[0156]
On the other hand, if the session ID (SID) of the transmission destination of the received connection frame is not null, the process proceeds from step S112 to S119.
If a service disable frame is received, the connection with the proxy received in step S117 is disconnected. Further, the proxy routing table PRT is searched using the service address in the service disable frame received in step S118 as a key, and an unusable flag is set in the description portion of the corresponding service address. That is, it grasps that the proxy or application of the service address is not available.
[0157]
In step S119, the current destination service address (end, end SA) of the session table SST is searched using the destination session ID as a key.
In step S120, the session current destination SA and the connection frame destination SA are compared. If they are equal, the connection destination is not changed, and the process advances from step S120 to step S115. If they are different, the connection destination is changed, so the destination SA in the session table SST is changed to a new destination SA, and then step S115. Proceed to
[0158]
The “connection process” shown in FIG. 21 will be described.
In step S131, the proxy routing table PRT is searched using the destination SA as a key, and a plurality of SAs of the next hop proxy (or application) are acquired. For example, assuming the operation of the proxy PF when the application PA shown in the network of FIG. 12 tries to connect to another application PE, the next hop of the proxy PF becomes the proxy PI. Therefore, the SA of the proxy PI is acquired in step S131.
[0159]
In step S131, it is determined whether or not a proxy for which a connection has been established exists in the acquired SA. If there is a proxy for which a connection has been established, the process proceeds from step S131 to S132, and if not, the process proceeds to step S133.
In step S132, the relay transfer of the data frame is started between the proxy that has sent the connection frame and the next proxy.
[0160]
In step S133, it is identified whether the SA acquired in step S131 includes the local proxy SA and there is already a connection to the destination SA application. If yes, the process proceeds from step S133 to S134, and if no, the process proceeds to S135.
[0161]
In step S134, relay transfer of the data frame is started between the proxy that has sent the connection frame and the next destination application.
In step S135, it is identified whether or not a connection different from the next hop already exists. If it exists, the connection is disconnected in the next step S136.
[0162]
If the connection is not completed, the processing after step S137 in FIG. 21 is repeatedly executed for all the next hops SA.
In step S139, one unprocessed next hop SA is selected. In step S140, the selected SA is compared with the SA of the proxy of the own node. If they match, the process proceeds from step S140 to S142, and if they do not match, the process proceeds to S141.
[0163]
In step S141, “proxy connection processing” is executed, and in step S142, “application connection processing” is executed. The contents of these processes are shown in FIG.
Further, if the connection is not yet completed even after all the next hop SAs have been connected, the process proceeds from step S137 to S138, and a service-disabled frame is notified toward the connection in the direction opposite to the frame that has arrived.
[0164]
Next, a description will be given with reference to FIG.
In the “proxy connection process”, in the first step S151, the resource table RST is searched using the SA of the next hop as a key, and the node ID of the next hop destination is acquired.
In the next step S152, the location table LCT is searched using the node ID with the next-hop proxy as a key, and the IP address of the connection destination is acquired. In step S153, the IP address of the own node is acquired from the location table LCT.
[0165]
In step S154, a connection frame is transmitted and connected to the proxy of the next hop SA using the obtained IP address.
In the “application connection process”, in the first step S156, the resource table RST is searched using the destination SA as a key to obtain the node ID.
In the next step S157, the location table LCT is searched using the node ID as a key, and the IP address of the connection destination is acquired. In step S158, the IP address of the own node is acquired from the location table LCT.
[0166]
In step S159, the obtained IP address is used to connect to the destination SA.
Next, the basic communication sequence shown in FIG. 15 will be described. PA, PF, PI, PD, PK, PH, and PB shown in FIG. 15 represent applications or proxies of the respective nodes shown in FIG. These applications and proxies are specified by service addresses.
[0167]
In the example of FIG. 15, the application PA first connects to the proxy PF, and the proxy PF transmits the connection frame to the proxy PI of the next hop. As a result, the proxy PI connects to the application PD.
Accordingly, a session is formed between the application PA and the application PD, and service provision is started using the session. In this case, the proxy PF, PI on the communication path relays communication.
[0168]
For example, when a node moves or a node leaves the network, a change in the network address of the node or a change in availability of the communication device occurs. Since this corresponds to CASE3 shown in FIGS. 24 and 25, the correspondence between the SA or node ID of the proxy and the network address is changed as shown in FIG. 25, and the link constituting the connection is changed.
[0169]
Accordingly, in response to the CASE3 switching request shown in FIG. 15, the communication path is changed between the proxy PF and PI, but even after the change, the proxy PF and PI are relayed between the application PA and the application PD. Service provision will continue.
On the other hand, when the node used by the user is changed, the application used is changed. Since this corresponds to CASE1 shown in FIGS. 24 and 25, the correspondence between the session ID and the SA of the end-to-end application (AP) changes as shown in FIG.
[0170]
In FIG. 15, in response to the switching request (CASE 1) for the proxy PF, the proxy PF transmits a connection frame to the proxy PK, and the proxy PK that has received the connection frame transfers the connection frame to the proxy PH.
Accordingly, the proxy PH connects to the application PB, a session is formed between the application PA and the application PB, and service provision is continued using the session.
[0171]
Next, a case will be described in which a copy of an application program (server) that is dynamically generated according to a change in the network form for seamless service provision is arranged on the network.
Here, the module of the application program is called an application agent. When a copy is created from one application agent, the application agent newly generated by the copy is called a shadow agent, and the copy source application agent is called a master agent.
[0172]
A shadow agent copied from one master agent is configured to have a part or all of the service providing function of the master agent. Also, one master agent and all shadow agents replicated therefrom are managed as one group. This group is called a service group.
[0173]
Further, in this embodiment, the master agent and shadow agent are handled as follows.
(1) The shadow agent is configured to be able to perform all or part of the service of the master agent.
(2) If the master agent cannot be used due to network conditions or resource conflicts, the shadow agent is used to provide the same service as the master agent. In addition, the switching between the master agent and the shadow agent is performed dynamically even during communication.
[0174]
(3) Communication between the application agent, the shadow agent, and the master agent is also performed by proxy relay. When a node change occurs, each agent is switched through a proxy to continuously provide a service.
(4) If the shadow agent cannot sufficiently achieve the service, the shadow agent connects to another shadow agent or master agent and relays at the own agent. This makes it appear as if the service is being performed by the own agent. Communication between a shadow agent and another shadow agent or master agent may be relayed by a proxy, and the service is continuously provided even when a network address change or a node change occurs. In order to realize such functions, for shadow agents that can perform only a part of services, to identify services that can be provided only by connecting to other agents belonging to the same service group as the services that can be provided Holds a service table AST.
[0175]
(5) The correspondence between the master agent and the shadow agent is held in the proxy routing table PRT of each node.
(6) When a shadow agent is created, the node ID, network address, and agent of the partner agent are added to the location table LCT, proxy routing table PRT, and resource table RST of the node where the master agent or shadow agent or both agents exist. Describe the service address and shadow / master correspondence.
[0176]
(7) When the network address of the node where the master agent exists is changed, after obtaining the shadow agent existing in the same service group from the proxy routing table PRT, change the network address to the node to which the shadow agent belongs. Notice. The notified node changes the location table LCT. Thereby, even when the position of the master agent changes, it can be grasped.
[0177]
(8) When the network address of the node where the shadow agent exists is changed, after obtaining the master agent existing in the same service group from the proxy routing table PRT, change the network address to the node to which the master agent belongs. Notice. The notified node changes the location table. This makes it possible to grasp even when the position of the shadow agent changes.
[0178]
As shown in FIG. 26, the proxy routing table PRT describes the correspondence between the master service address (master agent SA) and the shadow service address (shadow agent SA).
For example, “PE: PD (S)” and “PE: PB (S)” described in the proxy routing table PRT of the node ID: 1001 shown in FIG. 13 are the applications PD and PB shown in FIG. 12, respectively. Represents a shadow agent copied from the same application PE that is a master agent.
[0179]
Therefore, by searching the proxy routing table PRT, the relationship between the master agent and the shadow agent belonging to the same service group can be checked.
[0180]
On the other hand, for example, information as shown in FIG. 3 is described in the service table AST. In this example, master agents that belong to the same service group
http://hogehoge.com/undoukai.mpg
http://hogehoge.com/ensoku.mpg
http://hogehoge.com/yuuenchi.mpg
This is a case where the shadow agent referring to the service table AST can provide only two video services indicated by “yes”. This shadow agent is marked "no"
http://hogehoge.com/ensoku.mpg
However, the video service can be provided by using another shadow agent or master agent belonging to the same service group.
[0181]
When a master agent and a shadow agent exist on the network, the proxy performs the operation shown in FIG. The basic operation of the proxy is the same as that in FIGS. 20 to 22 described above, but step S131 in FIG. 21 is changed to step S131B in FIG.
In step S131B of FIG. 1, when the master agent or shadow agent of the destination SA exists, the proxy routing table PRT is searched using the SA of the corresponding agent as a key to obtain the next hop service. However, the destination is the SA of the agent used as a key. Note that the information on which the unusable flag is set is not referred to.
[0182]
The other operations of the proxy are the same as those in FIGS.
On the other hand, the master agent and the shadow agent execute the processing shown in FIG. The process of FIG. 2 will be described.
[0183]
When the own agent (master agent or shadow agent) receives data from the user in step S151, the own agent has a function of referring to the service table AST in the next step S152 and providing a service corresponding to the received data. Check whether there is any.
If the self-agent has a service providing function, the process proceeds from step S152 to S153, and the self-agent performs a process for providing the service.
[0184]
If the self-agent does not have a function for providing a service, the process proceeds from step S152 to S154. In step S154, the proxy routing table PRT is referred to search for other master agents or shadow agents belonging to the same service group.
If the search is successful, the process proceeds from step S154 to S155 to connect to another agent found. If no corresponding agent is found, the process proceeds to step S156 to notify service failure.
[0185]
In step S157, the data frame received from the user is transferred to the other agent connected in step S155.
If a function for providing a service corresponding to another agent connected in step S155 is provided, a service for the user is provided by the processing of the agent, and the process advances from step S158 to S159.
[0186]
If the function for providing the service corresponding to the other agent connected in step S155 is not provided, the service is not provided, so the process proceeds from step S158 to S154, and another agent is searched again from the proxy routing table PRT.
In step S159, data frame relay transmission is performed. That is, a data frame is relayed between a proxy that relays user data and another agent connected in step S155.
[0187]
As a result, the local agent itself only relays data frames, but other connected agents provide the service, so that the local agent provides the service from the perspective of the user receiving the service. appear.
When a new shadow agent is generated, various sequences as shown in FIGS. 4 and 5 can be executed.
[0188]
That is, immediately after generating a copy, the master agent of the copy source and / or the copied shadow agent describe the correspondence between the master agent and the shadow agent in the proxy routing table PRT.
Accordingly, the relationship between the generated shadow agent and the master agent can be grasped by referring to the proxy routing table PRT, so that the shadow agent can be used.
[0189]
Further, the replication source master agent and / or the replicated shadow agent describe the network address (NA), node ID, and agent service address (SA) of the partner node in the location table LCT and resource table RST of the local node.
As a result, even if the generated shadow agent is arranged on a different node from the master agent, the shadow agent can be searched and used.
[0190]
On the other hand, when the network address (NA) changes in the node where the master agent or shadow agent is operating, a message transfer sequence as shown in FIG. 6 is executed.
That is, when the network address changes in the node where the master agent is operating, the shadow agent is searched in step S471, and the NA update message is transmitted to all shadow agents in the same service group. Each shadow agent that has received the message changes the contents of the location table LCT according to the message.
[0191]
If the network address changes in the node where the shadow agent is operating, the master agent is searched in step S481, and an NA update message is transmitted to the master agent of the same service group. The master agent that has received the message changes the contents of the location table LCT according to the message.
[0192]
By using the master agent and the shadow agent, the configuration of the communication path can be changed, for example, as shown in FIG.
When a master agent and a shadow agent exist on the network, for example, a communication sequence as shown in FIG. 17 is executed.
[0193]
In the example of FIG. 17, when the application PD becomes unserviceable from the state in which service provision communication is performed between the application PA and the application (master agent or shadow agent) PD in step S701, the application PD becomes a proxy PI. The proxy PI sends a connection frame to the proxy PJ, and the proxy PJ connects to the application (master agent or shadow agent) PL. Therefore, the application PD and the PL are connected, and the service is provided by the application PL.
[0194]
Also, if the application PL becomes unable to provide the service from the state in which service provision communication is performed between the application PA and the application PL in step S702, the application PD connects to the proxy PI, and the proxy PI transmits the connection frame to the proxy PJ. Since the proxy PJ connects to the application (master agent or shadow agent) PE, the application PD and PE are connected, and the service is provided by the application PE.
[0195]
In addition, it is possible to recognize a state in which the service cannot be provided by detecting the following conditions. For example, when a service provider is accessed but no response is received, if a notification from the service provider (including an explicit message or a TCP layer connection termination message) is detected, the requested service can be serviced in the service table. There are cases where it was not.
[0196]
In step S703, the application PD can leave the node while continuing to provide the service.
Further, when a network change occurs in which the proxy PI is disconnected while the service is being provided between the applications PA and PE via the proxy PF, PI, and PJ (S705), the proxy PF becomes the proxy PJ. A switch notification is sent to. By this switching notification, the proxy PI leaves the communication path between the proxy PF and the proxy PJ, and the service provision between the applications PA and PE is continued as it is.
[0197]
Further, when a switching request is generated in the proxy PF while providing the service (S706), the connection frame transmitted by the proxy PF is transferred to the proxy PK, and the connection frame transmitted by the proxy PK is transferred to the proxy PH. The proxy PH connects with the application PB. Therefore, a communication path is formed between the application PA and the application PB via the proxies PF, PK, and PH, and the service moves to communication between the application PA and the application PB.
[0198]
That is, the session (one communication service between applications) formed between the application PA and the application PE is switched to the session formed between the application PA and the application PB. In this case, the proxy PF that performs switching notifies the switching destination application PB of the state where the communication service performed by the application PE is interrupted (the number of transferred bytes if data transfer is performed). Thereby, the application PB can take over the communication service of the suspended application PE.
[0199]
Further, the proxy PF that performs switching is the proxy PJ connected adjacent to the proxy PF in the chain of connections connected to the switching source application PE (the application PE if there is no other proxy on the way). The proxy PK connected adjacent to the proxy PF in the chain of connections leading to the switching destination application PB (if there is no other proxy on the way, the application PB ) To the communication connection formed between. Further, the switched communication connection is linked to a communication connection directly connected to the application PA (a proxy adjacent to the PF when another proxy is present in the middle), and communication is relayed between the communication connections. This allows service to continue.
[0200]
Further, when the link connecting two proxies (for example, PK and PH) existing on the route used for providing the communication service is switched from a wireless LAN to a wired LAN, for example, The communication service can be continued by reconstructing the communication connection between the proxies PK and PH (updating the contents of each table or changing the network address or the like).
[0201]
Next, a case where the proxy controls multicast data distribution will be described.
A node having a proxy is provided with a branch table JCT as shown in FIG. 13, FIG. 14, FIG. 23, and FIG. In the branch table JCT, as shown in FIG. 26, the correspondence between the input service address (SA) and the output service address is described for each session ID.
[0202]
That is, the proxy controls the input / output of data so as to transfer the data frame input from the input side service address to the proxy or application of the output side service address.
In the branch table JCT, a plurality of input side service addresses and output side service addresses can be described.
[0203]
A specific example of controlling the multicast communication path using the branch table JCT will be described with reference to FIG. In each branch table JCT shown in FIG. 19, the left side and the right side of the arrow represent the input side service address and the output side service address, respectively.
The proxy PG in FIG. 19A outputs the data frame input from the proxy PD to the proxy PE according to the branch table JCT, outputs the data frame input from the proxy PD to the proxy PF, and is input from the proxy PE. The data frame is output to the proxy PD, and the data frame input from the proxy PF is output to the proxy PD.
[0204]
For this reason, in the example of FIG. 19A, the multicast data frame sent from the application PA is input to the proxy PG via the proxy PD, branched into two systems at the proxy PG portion, and respectively sent to the proxy PE and PF. Sent out. Thereby, the data frame transmitted from the application PA is delivered to the two applications PB and PC, respectively.
[0205]
On the other hand, the data frame transmitted from the application PB reaches only the application PA, and the data frame transmitted from the application PC also reaches only the application PA.
Further, the proxy PG in FIG. 19B outputs the data frame input from the proxy PD to the proxy PE according to the branch table JCT, outputs the data frame input from the proxy PD to the proxy PF, and inputs from the proxy PE. The output data frame is output to the proxy PD, the data frame input from the proxy PF is output to the proxy PD, the data frame input from the proxy PE is output to the proxy PF, and the data frame input from the proxy PF is output. Output to proxy PE.
[0206]
For this reason, in the example of FIG. 19B, the multicast data frame sent from the application PA is input to the proxy PG via the proxy PD, branched into two systems at the proxy PG portion, and sent to the proxy PE and PF, respectively. Sent out.
The multicast data frame sent from the application PB is input to the proxy PG via the proxy PE, branched into two systems at the proxy PG portion, and sent to the proxy PD and PF, respectively.
[0207]
A multicast data frame sent from the application PC is input to the proxy PG via the proxy PF, branched into two systems at the proxy PG, and sent to the proxy PD and PE, respectively.
Therefore, the multicast data distribution destination can be controlled simply by rewriting the contents of the branch table JCT of each node where the proxy is arranged.
[0208]
For example, when the communication link between the proxy PG and PD is interrupted for a certain period of time, when the proxy PG relays based on the branch table, the transmission data to the proxy PD is stored in an internal cache, Only the communication between the application PB and the application PC is relayed. When the link between the proxy PG and PD is reestablished and the communication connection is reestablished, the proxy PG reads out and transmits data stored in the internal cache, and the three applications PA, PB, and PC Multicast communication service during
[0209]
If there is another proxy Px that can replace the proxy PD that has been disconnected, the proxy PG changes the communication connection with the proxy PD to a communication connection to the proxy Px, and the proxy Px passes through the proxy Px. A communication path with the application PA is secured. In this case, the proxy PG establishes a communication connection with the proxy Px, a communication connection with the application PB or a proxy PE directly connected to the proxy PG in a chain of subsequent communication connections, and an application PC or subsequent communication. In the chain of connections, the communication is connected to the proxy PF directly connected to the proxy PG, and communication is relayed based on the branch table.
[0210]
By forming a communication path as shown in FIG. 19A, it is possible to provide a communication service using the application PA as a broadcast server. Further, by forming a communication path as shown in FIG. 19B, it becomes possible to provide a service such as chat communication.
The operation of the proxy when controlling the multicast using the branch table JCT is as shown in FIGS. First, operations unique to multicast will be described with reference to FIG.
[0211]
When a multicast connection frame is received in step S201, the process advances to step S202 to identify whether or not a plurality of destination SAs are included. When a multicast connection frame including a plurality of destination SAs is received, after performing a predetermined process, the process proceeds to step S206 and subsequent steps. In step S206 and subsequent steps, connection processing is executed for each of a plurality of destination SAs specified in the multicast connection frame.
[0212]
The contents of this connection process are shown in FIG. The process of FIG. 8 will be described.
In step S221, the proxy routing table PRT is searched using the destination SA as a key, and a plurality of next-hop SAs are acquired.
In step S222, it is identified whether or not a proxy for which a connection has been established exists in the acquired SA.
[0213]
If it exists, the previous hop SA (input side service address) and the next hop SA (output side service address) are added to the branch table JCT in step S224.
[0214]
In the next step S225, the relay transfer of the data frame is started between the proxy that has sent the connection frame and the next proxy. In step S226, a multicast connection frame including the currently processed destination SA is transmitted.
On the other hand, in step S223, it is identified whether or not the SA obtained in step S221 includes the local proxy SA and the connection to the destination SA application. If yes, the process proceeds to step S227, and the previous hop SA (input side service address) and the next hop SA (output side service address) are added to the branch table JCT.
[0215]
In the next step S228, relay transfer of the data frame is started between the proxy that has sent the connection frame and the next destination application.
Among the SAs obtained in step S221, for the destination SA for which no connection has been established, “connection to proxy” or “connection to application” is executed in the processing after step S229 to establish the connection.
[0216]
If the connection is successful, the previous hop SA (input service address) and the next hop SA (output service address) are added to the branch table JCT in step S234.
When processing multicast, for example, a communication sequence shown in FIG. 18 is executed. That is, when another application PA is added to the communication between the application PC and the application PD, the application PA connects to the proxy PF during the service, and the proxy PF sends a connection frame to the proxy PI. Thereby, the branch table JCT on the node of the proxy PI is changed, and the data is also distributed to the application PA by the branch process of the proxy PI.
[0217]
When the application PD connects to the two applications PA and PC, the application PD connects to the proxy PI, the proxy PI sends a connection frame to each of the two proxies PF and PG, and the proxy PF connects to the application PA. The proxy PG connects to the application PC. Thereby, a multicast data distribution service can be performed among the three applications PD, PA, and PC.
[0218]
Next, specific control related to routing will be described. In this mode, each node is provided with a proxy routing table PRT, a resource table RST, and a location table LCT. However, in order to cope with a change in the network, information that cannot be acquired from the own node table is provided in other nodes. Search using. Also, when the network address of the own node changes, the update of the table accompanying it is notified to other nodes.
[0219]
The proxy performs the operations shown in FIG. 9, FIG. 10, and FIG. The specific operation is as follows.
When searching a table of another node, the search is executed between nodes having node IDs described in the resource table RST and the location table LCT.
[0220]
When searching the table of another node, the proxy issues a search message to the node described in the resource table RST or the location table LCT (S305).
When a search message is issued or when a search message is received, but does not have a corresponding search result, the processing after step S304 is performed.
[0221]
If it has a result corresponding to the search message, the result of the search is notified to the node that issued the search message in step S306.
When a plurality of the same search messages are received, only the first search message is processed, and the rest are ignored.
[0222]
There are several types of actual search and information notification methods as shown below. Since the forwarded message includes information for designating the search or notification method, the proxy that has received the message forwards the message according to the method designated in the message in step S305 or S316. .
(Method (1)) Search and notification by limiting the number of hops: A node that issues a message determines the maximum number of hops. The node that has received the message decrements the hop count by one, and if the hop count is not zero, transmits a further message to the node described in the resource table RST or the location table LCT.
[0223]
(Method (2)) Search and notification by hop match limit and sending node limit: In addition to method (1), the number of nodes that transmit the same message is limited to a certain number in each node.
(Method (3)) Search and notification by hop number limit and searched node information: In addition to method (1), the history of the node through which the message has passed is included in the message and transmitted. The node that has received the message does not transfer the message to the node that has already passed the message.
[0224]
(Method (4)) Search and notification using hop number limit and similarity or importance information between nodes: In addition to method (1), items related to importance or similarity are added to the resource table RST or location table LCT. In addition, messages are sent only to nodes with high importance and similarity. The importance in this case increases or decreases depending on the communication frequency with the corresponding node. The rate of change depends on the rate of change. The similarity degree indicates how much nodes described in the inter-node resource table RST or the location table LCT are duplicated.
[0225]
On the other hand, the storage capacity of each table in the communication device constituting each node is limited. In addition, if a large-capacity storage device is provided, the cost of the communication device increases. Therefore, it is necessary to limit the capacity of information held in each table while taking care not to reduce the routing efficiency.
[0226]
Therefore, in this embodiment, items of importance and increase / decrease rate are added to the resource table RST or the location table LCT. This importance level increases or decreases depending on the communication frequency with the corresponding node (S325, S327). The rate of change depends on the rate of change.
If the capacity of the table exceeds the capacity determined in advance by each node, in step S322, the information of the less important node is preferentially deleted, and management is performed so that the table capacity falls within the specified range.
[0227]
In this form, the distance between nodes in routing is different from the physical distance, and measures such as user frequency and ease of use, in which specific nodes often communicate with other specific nodes, are very important. become.
By the way, many companies and institutions currently have a firewall that blocks communication at the network layer (IP level). However, a communication network composed of the proxy of the present invention can communicate beyond this firewall. Is possible.
[0228]
A specific method for enabling communication beyond the firewall is as follows.
(1) Install a proxy with a firewall.
(2) Communication between proxies is realized by passing through an HTTP proxy or the like (which is completely different from the proxy of the present invention) using a transport protocol such as HTTP that is set to be able to exceed the firewall. To do.
[0229]
【The invention's effect】
According to the present invention, it is possible to recognize a proxy to be automatically reconnected without being aware of the user even when the network configuration is changed by holding the proxy routing table.
Further, by deleting information with low importance, even a node having a small storage capacity such as a small node can perform communication on the network. In addition, information can be efficiently managed on the network by suppressing the number of nodes that transmit search requests.
[0230]
At present, many companies and institutions have a firewall that blocks communication at the network layer (IP level). However, a communication network composed of proxies like the present invention operates beyond the firewall. Is possible. Even if this firewall allows proxy network communication, communication methods and procedures are limited compared to network layer communication, improving user convenience while ensuring a certain level of security. Can be made.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an operation of a proxy when a master and a shadow agent exist.
FIG. 2 is a flowchart showing operations of a master and a shadow agent.
FIG. 3 is a schematic diagram illustrating a configuration example of a service table used by a master and a shadow agent.
FIG. 4 is a sequence diagram illustrating an example of a shadow agent generation sequence.
FIG. 5 is a sequence diagram illustrating an example of a shadow agent generation sequence.
FIG. 6 is a sequence diagram illustrating an example of a message transfer sequence.
FIG. 7 is a flowchart showing proxy operation (1) related to multicast;
FIG. 8 is a flowchart showing a proxy operation (2) related to multicast;
FIG. 9 is a flowchart showing a proxy operation (1) related to routing;
FIG. 10 is a flowchart showing a proxy operation (2) related to routing.
FIG. 11 is a flowchart showing a proxy operation (3) related to routing;
FIG. 12 is a block diagram illustrating a configuration example of a network.
FIG. 13 is a schematic diagram showing a configuration example (1) of a table in each node.
FIG. 14 is a schematic diagram showing a configuration example (2) of a table in each node.
FIG. 15 is a sequence diagram showing a basic communication sequence for providing a service.
FIG. 16 is a block diagram illustrating a dynamic change example of a service.
FIG. 17 is a sequence diagram showing a communication sequence when a master and a shadow agent exist.
FIG. 18 is a sequence diagram showing a multicast communication sequence.
FIG. 19 is a block diagram illustrating a configuration example of a communication path using a branch table.
FIG. 20 is a flowchart showing a basic operation (1) of a proxy.
FIG. 21 is a flowchart showing basic operation (2) of the proxy;
FIG. 22 is a flowchart showing basic operation (3) of the proxy;
FIG. 23 is a block diagram illustrating a functional configuration of a proxy.
FIG. 24 is a block diagram showing connection management.
FIG. 25 is a schematic diagram showing changes in connection management;
FIG. 26 is a schematic diagram showing the configuration of each table on a node.
FIG. 27 is a schematic diagram illustrating a configuration of an inter-proxy frame.
FIG. 28 is a schematic diagram showing a configuration of a control command.
FIG. 29 is a schematic diagram showing a configuration of an inter-proxy message.
FIG. 30 is a sequence diagram illustrating a control sequence when switching between a proxy and an application.
FIG. 31 is a block diagram illustrating an example of a communication path when switching between a proxy and an application.
FIG. 32 is a sequence diagram illustrating a control sequence when a proxy is added to a session.
FIG. 33 is a block diagram illustrating an example of a communication path when a proxy is added to a session.
FIG. 34 is a sequence diagram showing a control sequence for deleting a proxy from a session.
FIG. 35 is a block diagram illustrating an example of a communication path when a proxy is deleted from a session.
FIG. 36 is a sequence diagram showing a control sequence when a proxy on a session is replaced.
FIG. 37 is a block diagram illustrating an example of a communication path when a proxy on a session is replaced.
FIG. 38 is a block diagram illustrating a configuration example of a communication system.
FIG. 39 is a block diagram illustrating a configuration example of a mobile terminal.
FIG. 40 is a schematic diagram illustrating an example of information held by a service management unit SR.
FIG. 41 is a schematic diagram illustrating an example of information held by the position management unit LR.
FIG. 42 is a schematic diagram illustrating an example of information held by the session management unit SM.
FIG. 43 is a block diagram illustrating a configuration example of a communication system.
FIG. 44 is a block diagram illustrating a configuration example of a network.
FIG. 45 is a block diagram showing a movement model of nodes and services.
FIG. 46 is a sequence diagram showing a location information update procedure when the terminal is moving.
47 is a graph showing the number of issued position information update instructions. FIG.
FIG. 48 is a graph showing a location search success rate.
FIG. 49 is a graph showing a location search success rate.
FIG. 50 is a block diagram illustrating a configuration example of a network.
FIG. 51 is a sequence diagram showing a service movement example (1).
FIG. 52 is a sequence diagram showing a service movement example (2).
FIG. 53 is a sequence diagram showing a simplified control sequence when a proxy is added to a session.
FIG. 54 is a sequence diagram showing a simplified control sequence when deleting a proxy from a session.
FIG. 55 is a sequence diagram showing a simplified control sequence when replacing a proxy on a session.
[Explanation of symbols]
1,3 application
2 proxy
4 nodes
5 Browser
6 Proxy
7 Web server
8 nodes
9 Database
10 software
11 Server application
12 Client application
13 Proxy
14 Agent
15 Link switching unit
16, 17, 18 links
21 Ethernet (registered trademark) communication adapter
22 Wireless LAN adapter
23 PHS communication adapter
30 Mobile terminal
40 network
51, 52, 53 Subnetwork
54 Wide area network
55, 59, 60, 61, 66, 67 Mobile terminal
56,62 fixed terminal
57, 58, 64, 65 base station
63 TAP
101,102 application
103 sessions
104, 105, 106 proxy
107, 108, 109, 110 Communication connection
LR Location Management Department
SM Session Management Department
SR Service Management Department
501 Proxy control unit
502 Session Management Department
503 Cache Management Department
504 Connection Management Department
505 Path management department
506 Link Management Department
507 Communication device
PRT proxy routing table
RST resource table
LCT location table
JCT branch table
SST session table
AST service table

Claims (14)

In a communication system in which at least one of an application program and a proxy that relays communication is provided in each communication device that configures a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. Is a routing control method used to control each node where
Manage the service address identifying each application program and each proxy, and the session representing each communication;
Manage the location of each application program and the location of each proxy as a resource table,
The proxy routing table shows the correspondence between the first service address representing the destination application program and the second service address representing another proxy located at the next hop of the local proxy on the communication path connected to the destination. Manage as
Manage the network address of the communication device that exists in each node as a location table,
When the information managed in the local node is updated or when it is necessary to search for information that does not exist in the local node, a message is sent to other nodes managed in the resource table or location table. Send
When the local node receives a message requesting a search from another node, and the requested information exists in the local node, the search result is sent to the message originator, and the local node searches from the other node. If the requested information does not exist in the local node, or if a message indicating information update is received, if the number of hops from the message source does not exceed the limit value, A routing control method, wherein the content of a received message is transferred to another node managed in the resource table or location table. 2. The routing control method according to claim 1, wherein when a plurality of identical messages transmitted by other nodes are received, only one message is processed, and the remaining messages are ignored. Control method. 2. The routing control method according to claim 1, wherein the number of transfer destination nodes when each node transfers a received message to another node is limited to a predetermined number. In the routing control method of Claim 1,
The history information about the node through which the message transferred between a plurality of nodes has passed and the node to which the same message has already been transmitted is included in the message, and when the message received by each node is transferred, the history information is examined. A routing control method, wherein nodes included in the node are excluded from transfer destination nodes. In the routing control method of Claim 1,
For each of the other nodes managed by the own node, manage information representing at least one of the communication frequency between the own node and the other node and the similarity of the managed information,
A routing control method, wherein when a message received by each node is transferred, a node having a high communication frequency or a node having a high degree of similarity is preferentially selected as a transfer destination. In the routing control method of Claim 1,
For each of the other nodes managed by the own node, manage the importance information indicating the communication frequency between the own node and the other nodes,
A routing control method characterized in that, when the capacity of information managed in each table exceeds a limit value, information related to the node having low importance is preferentially deleted from the table. In a communication system in which at least one of an application program and a proxy that relays communication is provided in each communication device that configures a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network. Is a routing control device used to control each node where
A service address that identifies each application program and each proxy; a session management means that manages a session that represents each communication; a resource table that manages the location of each application program and the location of each proxy;
A proxy that manages the correspondence between a first service address that represents a destination application program and a second service address that represents another proxy located at the next hop of the local proxy on the communication path connected to the destination A routing table;
A location table for managing network addresses of communication devices existing in each node;
When the information managed in the local node is updated or when it is necessary to search for information that does not exist in the local node, a message is sent to other nodes managed in the resource table or location table. Message sending means for sending;
A search result transmission means for receiving a message requesting a search from another node by the own node and transmitting the result of the search to the sender of the message when the requested information exists in the own node;
When the local node receives a message requesting a search from another node and the requested information does not exist in the local node, or when a message indicating an update of the information is received, the hop count from the message source is A routing control device comprising message transfer means for transferring the content of a received message to another node managed in the resource table or location table if the limit value is not exceeded. 8. The routing control device according to claim 7, wherein when the search result transmission means and the message transfer means receive a plurality of the same messages transmitted by other nodes, the search result transmission means and the message transfer means perform processing only for one message, and the rest A routing controller characterized by ignoring the message. The routing control device according to claim 7,
A routing control device, further comprising transfer destination node number limiting means for limiting the number of transfer destination nodes to a predetermined number when each node transfers a received message to another node. The routing control device according to claim 7,
When the message transferred between a plurality of nodes includes the history information of the passed node, when transferring the message received by each node, the history information is checked and the node included in the message is transferred to the destination node. A routing control device, further comprising history identifying means for excluding from the above. The routing control device according to claim 7,
Communication frequency management means for managing information representing at least one of the communication frequency between the own node and the other node and the similarity of the managed information for each of the other nodes managed by the own node;
A routing control device, further comprising a transfer destination selection means for preferentially selecting a node having a high communication frequency or a node having a high similarity as a transfer destination when transferring a message received by each node. . The routing control device according to claim 7,
For each of the other nodes managed by the own node, importance management means for managing importance information indicating the communication frequency between the own node and the other nodes;
And a table information deleting unit that preferentially deletes information about the node having low importance from the table when the capacity of information managed in each table exceeds a limit value. Routing control device. Applicable to a communication system in which at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network , A recording medium storing a computer-executable control program for routing control of each node where the proxy is arranged, and the control program includes:
A service address for identifying each application program and each proxy, and a procedure for managing a session representing each communication;
A procedure for managing the location of each application program and the location of each proxy as a resource table;
The proxy routing table shows the correspondence between the first service address representing the destination application program and the second service address representing another proxy located at the next hop of the local proxy on the communication path connected to the destination. As a procedure to manage as
A procedure for managing network addresses of communication devices existing in each node as a location table;
When the information managed in the local node is updated or when it is necessary to search for information that does not exist in the local node, a message is sent to other nodes managed in the resource table or location table. The steps to send,
When the local node receives a message requesting a search from another node and the requested information exists in the local node, a procedure for transmitting the search result to the message originator;
If the local node receives a message requesting a search from another node and the requested information does not exist in the local node, or if a message indicating an update of the information is received, the hop count from the message source is A recording medium comprising: a procedure for transferring the content of a received message to another node managed by the resource table or the location table if the limit value is not exceeded. Applicable to a communication system in which at least one of an application program and a proxy that relays communication is provided in each communication device that constitutes a node, and a plurality of nodes including the application program are connected to each other via a plurality of proxies and a predetermined network A computer-executable control program for routing control of each node where the proxy is arranged,
A service address for identifying each application program and each proxy, and a procedure for managing a session representing each communication;
A procedure for managing the location of each application program and the location of each proxy as a resource table;
The proxy routing table shows the correspondence between the first service address representing the destination application program and the second service address representing another proxy located at the next hop of the local proxy on the communication path connected to the destination. As a procedure to manage as
A procedure for managing network addresses of communication devices existing in each node as a location table;
When the information managed in the local node is updated or when it is necessary to search for information that does not exist in the local node, a message is sent to other nodes managed in the resource table or location table. The steps to send,
When the local node receives a message requesting a search from another node and the requested information exists in the local node, a procedure for transmitting the search result to the message originator;
If the local node receives a message requesting a search from another node and the requested information does not exist in the local node, or if a message indicating an update of the information is received, the hop count from the message source is A control program comprising: a procedure for transferring the content of a received message to another node managed in the resource table or location table if the limit value is not exceeded.

Images