JP4492575B2 - Relay device and communication system - Google Patents

Description

  The present invention relates to a technique for relaying data transmitted and received between communication devices.

  By using technologies such as VPN (Virtual Private Network) and tunneling, it is possible to relay data transmitted from terminals arranged in the private network to terminals in other private networks via the Internet. is there. For example, it is possible to relay data between terminals connected to the LAN via the Internet by connecting the LAN of the head office and the LAN of the branch office via VPN.

  Also in the following Patent Document 1, a technique for relaying data between local systems connected via the Internet is disclosed. In this technology, a TCP connection is established by accessing a relay server on the Internet from each terminal arranged in the local system, and data is transmitted and received between the local systems using the TCP connection.

Japanese Patent Laid-Open No. 2002-217743

  By using VPN and tunneling technologies, data can be transmitted and received between LANs connected via the Internet. However, these technologies are systems constructed with fixed settings. That is, a connection setting between LANs is fixedly performed in a relay device installed between each LAN and the Internet. Therefore, for example, there is no problem if you want to maintain a VPN constantly, such as a company headquarters and branch offices, but you cannot handle the case where you want to try to connect to a different private network dynamically. .

  In view of the above problems, an object of the present invention is to provide a system capable of dynamically setting data relay between networks connected via the Internet.

In order to solve the above problem, the invention described in claim 1 is a relay device capable of communicating with the first communication device, wherein the relay unit relays the data transmitted from the first communication device to another relay device; The server device is inquired about the status of the other relay device, and when the other relay device is in a state of accepting the connection, a connection request is made to the other relay device and the connection with the other relay device is made. Holding means for dynamically establishing and holding a relay connection in the network, and when the relay connection is established, a list of device names of communication devices connected to the LAN to which the relay device belongs is added to the other relay device. Means for exchanging the list of device names by receiving from the other relay device a list of device names of communication devices connected to the LAN to which the other relay device belongs ,
The second communication device is connected to the LAN to which the other relay device belongs, and a data transmission request specifying the device name of the second communication device associated with the other relay device in the exchanged list as the destination the and means for receiving from the first communication device, before SL by the data transmitted from the first communication device relays to the other relay device, further the data is relayed to the second communication device It is characterized by that.

  According to a second aspect of the present invention, in the relay device according to the first aspect, the holding unit includes a unit that connects and holds a relay connection with a plurality of relay devices, and the relay unit includes: Means for relaying data to a plurality of relay devices using a plurality of relay connections.

According to a third aspect of the present invention, in the relay apparatus according to the second aspect, the holding means includes means for individually disconnecting a relay connection held between a plurality of relay apparatuses. And
According to a fourth aspect of the present invention, in the relay apparatus according to the first aspect, the holding means includes means for connecting and holding a relay connection with another relay apparatus according to designation from the communication apparatus. It is characterized by that.
According to a fifth aspect of the present invention, in the relay apparatus according to the first aspect, the holding means includes means for connecting and holding a relay connection with another relay apparatus in accordance with designation from the communication apparatus. When the connection specification of the relay connection to the specific relay device is received from the communication device, if the relay connection is already held with the specific relay device, the relay connection already formed The connection is shared.

The invention according to claim 6 is a communication system for relaying data between terminals, and is a first relay device capable of communicating with the first communication device, a server device, and a second relay capable of communicating with the second communication device. And the first relay device inquires of the server device about the state of the second relay device, and when the second relay device is in a state of accepting connection, the first relay device A holding unit that makes a connection request and dynamically establishes and holds a relay connection with the second relay device, and connects to the LAN to which the first relay device belongs when the relay connection is established A list of communication device names sent to the second relay device, and a list of device names of communication devices connected to the LAN to which the second relay device belongs is received from the second relay device, exchange a list of the device name Means that, the second communication device is connected to the LAN to the second relay device belongs, the device name of the second communication device is associated with the second relay device in the list has been replaced as the destination and means for receiving the specified data transmission request from the first communication device, a pre-SL by the first relay apparatus relays the data transmitted from the first communication device to the second relay device, The second relay device further relays and transmits data to the second communication device.

A seventh aspect of the present invention is the communication system according to the sixth aspect , wherein the first communication device and the second communication device are arranged in different private networks, respectively, and the first communication device and the second communication device are arranged from the external network. The network configuration is such that a connection request for a TCP connection cannot be made to one communication device and the second communication device.
According to an eighth aspect of the present invention, in the communication system according to the sixth aspect, the holding means includes means for connecting and holding a relay connection with another relay apparatus according to designation from the communication apparatus. It is characterized by that.
A ninth aspect of the invention is the communication system according to the sixth aspect, wherein the holding means includes means for connecting and holding a relay connection with another relay apparatus according to designation from the communication apparatus. When a relay connection is already formed between the relay devices corresponding to the request from the communication device, the other communication devices also share the connection.

  The relay device of the present invention inquires of the server device about the status of another relay device, makes a connection request when the other relay device is in a state of accepting connection, and is used for relaying with another relay device Establish and maintain a connection. Therefore, a communication device that can communicate with the relay device can perform communication via a public network with a communication device that can communicate with another relay device.

  In addition, the relay apparatus of the present invention can connect and hold a relay connection with a plurality of relay apparatuses. Therefore, when the communication device that wants to communicate belongs to different networks, it is possible to individually generate a plurality of connections.

  Further, the relay device of the present invention can individually disconnect relay connections held between a plurality of relay devices. Therefore, it is possible to maintain only the connections that need to be communicated, and resources can be used effectively.

{First embodiment}
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a communication system according to the first embodiment. In this communication system, two LANs 10 and 20 are connected via a WAN 30. The LANs 10 and 20 are, for example, corporate LANs, and the WAN 30 is a public network such as the Internet. That is, two different private LANs 10 and 20 are connected via a public network such as the Internet.

  As shown in the figure, two communication devices 11 and 12 and a relay device 15 are connected to the LAN 10. The LAN 10 is connected to the WAN 30 via the gateway 16. Two communication devices 21 and 22 and a relay device 25 are connected to the LAN 20. The LAN 20 is connected to the WAN 30 via the gateway 26.

  The communication devices 11 and 12 are terminals such as personal computers and have a network function. Specifically, TCP / IP is implemented, and communication with the relay device 15 and other computers connected to the LAN 10 using TCP / IP is possible. Similarly, the communication devices 21 and 22 are also mounted with TCP / IP, and can communicate with the relay device 25 and other computers connected to the LAN 20 using TCP / IP. Further, the relay apparatuses 15 and 25 and the gateways 16 and 26 can also communicate using TCP / IP.

  A server device 35 is connected to the WAN 30. The WAN 30 is a public network such as the Internet as described above. Therefore, a terminal connected to the LAN 10, 20 or WAN 30 can establish a TCP connection by specifying the global IP address of the server device 35.

  On the other hand, the communication devices 11, 12, 21, and 22 and the relay devices 15 and 25 connected to the LANs 10 and 20 are assigned private IP addresses. The gateways 16 and 26 form a firewall so that a connection in which an internal terminal is designated directly from an external network cannot be performed. Therefore, a terminal connected to the WAN 30 is restricted from making a TCP connection connection request to the relay apparatuses 15 and 25. In the present embodiment, as will be described later, since the server device 35 functions as a SIP server (SIP proxy server, registration server), the server device 35 can communicate with a specific port for the relay devices 15 and 25. As described above, the gateways 16 and 26 are set.

  Table 1 is a table showing a registration example of the relay device database 351 managed by the server device 35. In this example, three relay apparatuses A to C are registered. The relay devices A to C are device names attached to the relay device 15 and the relay device 25, for example. For each of the relay devices A to C, a URL, an IP address, and a login status flag are set.

  Note that the IP address of each relay device registered in the relay device database 351 is not converted by the gateway using a function such as NAT (Network Address Translation) or IP masquerade, but an IP address in the private network of each relay device. It is a global IP address. For example, the relay device 15 is assigned a private address in the LAN 10, but when accessing the server device 35, the IP address is converted into a global IP address in the gateway 16.

  Each relay device A to C connects to the server device 35 and logs into the server device 35. In the “status” field of the relay device database 351, information indicating whether each of the relay devices A to C is currently logged in to the server device 35 or in a logout state is set. When each relay device is in the login state, the server device 35 can determine that it is ready to establish a TCP connection with each other relay device. In other words, the state in which the relay device is logged in to the server device 35 indicates that the connection request for the TCP connection sent from the partner terminal can be accepted.

  A flow of communication processing in the communication system having the above configuration will be described with reference to FIGS. FIG. 2 is a diagram showing an overall processing flow of the communication system including the relay devices 15 and 25 and the server device 35. In the following description, communication between the relay devices 15 and 25 and the server device 35 will be described as an example using SIP (Session Initiation Protocol), but other protocols may be used. .

  Each of the relay devices 15 and 25 transmits a SIP “REGISTER request message” to the server device 35 at the time of initialization or periodically, and notifies the server device 35 of location information (IP address, port number, etc.) of the relay device. is doing. The server device 35 manages the relay device database 351 shown in Table 1 based on this position information. The server device 35 can communicate with each relay device beyond the gateway based on the position information. In FIG. 2, in the initial state, the relay device 15 and the relay device 25 are logged in to the server device 35. First, the relay device 25 notifies the server device 35 of logout status information (step S101), and the server device 35 responds thereto (S102). The server device 35 executes logout processing of the relay device 25 and updates the “status” field of the relay device 25 in the relay device database 351 to logout.

  In this state, when the relay device 15 makes a status information notification request to the server device 35 (S103), the server device 35 responds (S104), and then notifies that the relay device 25 is in the logout state. (S105). The relay device 15 responds to this notification (S106).

  Next, the relay device 25 notifies the server device 35 of login status information (step S107), and the server device 35 responds thereto (S108). The server device 35 executes the login process of the relay device 25 and updates the “status” field of the relay device database 351 to login. Further, the server device 35 notifies the relay device 15 that the relay device 25 has entered the login state (S109). The relay device 15 responds to this notification (S110).

  When the relay device 15 receives the notification that the relay device 25 has entered the login state, the relay device 15 next transmits a connection request for the relay device 25 to the server device 35 (S111). This connection request is a SIP “INVITE request message” as illustrated in the figure, and includes TCP connection information in a body part following a blank line. In the example shown in the figure, the IP address (200.1.1.1) of the relay device 15 (source), the TCP port number (6109), and the like are included. The server device 35 relays this connection request to the relay device 25 (S112). In response to this request, the relay device 25 transmits a response to permit connection to the server device 35 (S113). This response is a SIP “200 OK response message” as illustrated in the figure, and includes TCP connection information in the body part following the blank line. In the example shown in the figure, the IP address (200.2.2.2) of the relay device 25 (source), the TCP port number (7109), and the like are included. The server device 35 relays this response to the relay device 15 (S114). As described above, the relay device 15 and the relay device 25 use the SIP INVITE request and the OK response to exchange TCP connection information and perform negotiation for establishing the TCP connection. In response to this response, the relay device 15 transmits a TCP connection request to the relay device 25 (S115). Thereby, a TCP connection is established between the relay device 15 and the relay device 25.

  The above processing is executed by a network administrator of the LAN 10 or LAN 20, for example. That is, if the network administrator prepares to dynamically execute a connection with another LAN, the relay device in the network is logged into the server device 35 as shown in step S107. is there. As a result, preparation for receiving a TCP connection request from another relay apparatus is completed. If the network administrator wants to establish a connection with another LAN, the network administrator accesses the server device 35 to acquire the state of the partner relay device, and the partner relay device enters the login state. When it is known that the connection is present, a connection request is transmitted to the server device 35.

  In other words, in the present invention, the relay device 15 transmits a SIP INVITE request via the server device 35 to establish a TCP connection (media session) for relay. That is, since a relay path as a media session is generated using a call control protocol, a relay communication path can be dynamically established.

  When a TCP connection is established between the relay device 15 and the relay device 25 in this way, the relay device 15 and the relay device 25 hold the TCP connection. When the relay device 15 receives data to be transmitted from the communication devices 11 and 12 to the communication devices 21 and 22, the relay device 15 relays the data to the relay device 25. The relay device 25 further relays the relayed data to the communication devices 21, 22, etc. (S116). Similarly, data transmitted from the communication devices 21 and 22 are relayed to the communication devices 11 and 21 through the relay device 25 and the relay device 15 (S117).

  Note that, in order to perform communication between the LAN 10 and the LAN 20 via such a WAN 30, the relay apparatuses 15 and 25 manage a list of apparatus names of communication apparatuses connected to the respective LANs. Then, when a TCP connection is established between the relay device 15 and the relay device 25, this list is exchanged. When the communication device connected to the LAN 10 communicates with the communication device connected to the LAN 20, the destination LAN relay device and the device name of the destination communication device are specified together. do it. That is, since a unique device name is assigned to the relay device using this communication system (registered in the relay device database 351), the relay device name and the communication device name are specified together. By doing so, the destination communication device can be uniquely identified. For example, a name such as communication device name @ relay device name may be used. Also, each relay device is specified by the communication device name @ relay device name because the correspondence between the communication device name and the IP address is known for the communication device connected to the LAN to which it is connected. It is possible to relay data to a communication device.

  When the data transmission / reception between the communication devices is completed and the connection between the relay device 15 and the relay device 25 becomes unnecessary, the network administrator disconnects the connection. First, the relay device 15 transmits a disconnection request for the relay device 25 to the server device 35 (S118). The server device 35 relays this request to the relay device 25 (S119). The response from the relay device 25 is transmitted to the server device 35 (S120) and relayed to the relay device 15 (S121).

  FIG. 3 is a flowchart focusing on the processing of the relay device 15 in the processing described in FIG. First, the relay device 15 transmits a relay connection start request to the server device 35 (step S201). In this start request, the relay destination relay device 25 is specified. If it becomes clear from the response from the server device 35 that the relay device 25 as the relay destination is logged out (NO in S202), the process waits until a login notification is received (S203). When the login notification is received, the process proceeds to step S204.

  If it is determined in step S202 that the relay device 25 as a relay destination is logged in, TCP connection information is generated (S204), and a connection request is transmitted (S205). Then, it waits for a response from the relay device 25 (S206), and when receiving the response, analyzes the TCP connection information in the response (S207). That is, the port number information included in the response transmitted from the relay device 25 is acquired. Then, a TCP connection is made to the relay device 25 (S208).

  When the communication device 11 or the like transmits relay data while the TCP connection is established and held (YES in S209), the data is relayed and transmitted to the communication device 21 or the like (S210). When relay data for the communication device 11 or the like is received (YES in S211), the data is relayed and transmitted to the relay destination communication device 11 or the like (S212). If a disconnection request is received from the relay device 25 (YES in S213), a response is transmitted (S214), and the TCP connection is disconnected (S215).

  On the other hand, when a disconnection request is made by the network administrator of the LAN 10 (S216), the disconnection request is transmitted to the relay device 25 (S217), and if a response is received (YES in S218), the TCP The connection is disconnected (S219).

  FIG. 4 is a flowchart focusing on the processing of the relay device 25 in the processing described in FIG. First, the network administrator of the LAN 20 determines whether to prepare for connection with another LAN. When preparing to connect to another LAN, the relay device 25 is operated to enable the relay function. When the relay function is enabled (YES in step S301), a login command is transmitted to the server device 35 (S302). And a response is received from the server apparatus 35 (S303), and the process which validates a relay function is completed.

  In this way, the relay device 15 dynamically establishes a TCP connection to the relay device 25 if the relay destination relay device 25 is in a login state, that is, if the relay device 25 is in a state of accepting a connection, Data can be transmitted and received via the WAN 30 such as the Internet. For example, when traffic constantly occurs like a head office and a branch office of a certain company, a conventionally used VPN may be used to connect LANs fixedly. On the other hand, when it is desired to perform data communication by connecting to a different network via the WAN 30 at an arbitrary timing, the communication system of this embodiment may be used.

  Further, according to the communication system of the present embodiment, even when the connection environment (IP address or port number) of the partner relay device is changed, the relay device first performs negotiation (S111 to S114). It is possible to reliably establish a data relay connection.

  In addition, the relay devices 15 and 25 of the present embodiment can establish TCP connections with a plurality of relay devices. For example, as shown in FIG. 5, the relay device 15 can individually establish a TCP connection with the three relay devices 25, 45, and 55. A method for establishing a TCP connection with the relay devices 45 and 55 is the same as the processing performed for the relay device 25. Each relay device 15, 25, etc. establishes a TCP connection with a plurality of relay devices and relays data to the plurality of relay devices. In the example of FIG. 5, the relay device 15 relays data transmitted from a certain communication device to the relay device 45 and relays data transmitted from another communication device to the relay device 55.

  The method for cutting the TCP connection with each of the relay devices 45 and 55 is the same as the processing performed for the relay device 25. That is, a TCP connection can be individually established with a plurality of relay apparatuses 25, 45, and 55, and the TCP connection can be disconnected individually.

  Conventionally, in a VPN or the like, when a plurality of LANs are connected, the plurality of LANs are connected as one VPN. On the other hand, the communication system according to the present embodiment can be individually connected only to the relay device that wants to communicate, and can be disconnected individually from the relay device that no longer needs to perform communication. An efficient communication system can be constructed without consuming resources.

{Second Embodiment}
Next, a second embodiment of the present invention will be described. In the first embodiment, the relay apparatuses are dynamically connected according to instructions from the network administrator. In the second embodiment, connection between relay devices is performed by designation from a communication device. Specifically, in the first embodiment, the network administrator performs an operation of connecting or disconnecting the relay devices, assuming a state of communication occurring between the communication devices. On the other hand, in the second embodiment, connection / disconnection control between relay apparatuses is more dynamically performed in response to communication processing generated from the communication apparatus. In the following description, the same description as in the first embodiment is omitted.

  FIG. 6 is a configuration diagram of a communication system according to the second embodiment. Although a LAN 40 is added in FIG. 6 in addition to the system configuration of FIG. 1, the basic system configuration is the same as that of the first embodiment. Also for the LAN 40, a communication device 41 and a relay device 45 are connected, and the LAN 40 is connected to the WAN 30 via a gateway 46.

  The relay devices 15, 25, and 45 include relay connection databases 151, 251 and 451, respectively. Table 2 is a table showing a registration example of the relay connection database 151 included in the relay device 15.

  The relay connection database 151 is a database that manages the TCP connection currently established by the relay device 15. In the “client” field, a device name of a communication device that requests connection with the relay device (referred to as a request source communication device in the following description as appropriate) is set. ClientX and ClientY in the table are names of devices assigned to the communication devices 11 and 21, for example. In the “relay destination URL” and “IP address” fields, the URL and IP address of the relay device of the relay destination are set. The port number of the generated TCP connection is set in the “connection number” field, and the time when the TCP connection is generated is set in the “generation time” field.

  In the present embodiment, a TCP connection is established with a communication destination relay device according to the designation from the request source communication device, but communication can be performed using this TCP connection. Only communication equipment. That is, as shown in Table 2, there is a one-to-one correspondence between communication devices and TCP connections.

  The contents of the relay connection databases 251 and 451 are the same as those of the relay connection database 151 shown in Table 2. The state of the TCP connection currently established by each of the relay devices 25 and 45 is registered.

  A flow of communication processing in the communication system having the above configuration will be described with reference to FIGS. FIG. 7 is a diagram showing an overall processing flow of the communication system including the communication devices 11 and 12, the relay devices 15 and 25, and the server device 35. In the following description, communication between the relay devices 15 and 25 and the server device 35 will be described as an example using SIP (Session Initiation Protocol), but other protocols may be used. .

  As in the first embodiment, each of the relay devices 15 and 25 transmits a SIP “REGISTER request message” to the server device 35 at the time of initialization or periodically, and the location information (IP address, port) of the relay device. Number or the like) to the server device 35. In FIG. 7, in the initial state, the relay device 15 and the relay device 25 are logged in to the server device 35. First, the relay device 25 notifies the server device 35 of logout status information (step S401), and the server device 35 responds thereto (S402). The server device 35 executes logout processing of the relay device 25 and updates the “status” field of the relay device 25 in the relay device database 351 to logout.

  In this state, the communication device 11 transmits a data relay transmission request and a status confirmation request specifying the relay device 25 to the relay device 15 (S403). When the relay device 15 makes a status information notification request to the server device 35 (S404), the server device 35 responds (S405), and then notifies that the relay device 25 is in a logout state (S406). . The relay device 15 responds to this notification (S407). Further, the relay device 15 notifies the communication device 11 that the relay device 25 is in a logout state (S408). As a result, the communication device 11 stands by until the relay device 25 enters the login state.

  Next, the relay device 25 notifies login status information to the server device 35 (step S409), and the server device 35 responds to this (S410). The server device 35 executes the login process of the relay device 25 and updates the “status” field of the relay device database 351 to login. Further, the server device 35 notifies the relay device 15 that the relay device 25 has entered the login state (S411). The relay device 15 responds to this notification (S412). Further, the relay device 15 notifies the communication device 11 that the relay device 25 has entered the login state (S413).

  Upon receiving the notification in S413, the communication device 11 that has been waiting makes a relay transmission request specifying the relay device 25 again (S414). In this embodiment, the communication device 11 waits until it receives a notification that the relay device 25 has entered the login state. However, the communication device 11 does not wait for such notification and periodically issues a relay transmission request. A mode of transmitting to the relay device 15 may be possible.

  When receiving the relay transmission request from the communication device 11, the relay device 15 transmits a connection request for the relay device 25 to the server device 35 (S415). This connection request is an SIP “INVITE request message” as described in the first embodiment, and includes TCP connection information. The server device 35 relays this connection request to the relay device 25 (S416). In response to this request, the relay device 25 transmits a response to permit connection to the server device 35 (S417). As described in the first embodiment, this response is a SIP “200 OK response message” and includes TCP connection information. The server device 35 relays this response to the relay device 15 (S418). In this way, the relay device 15 and the relay device 25 exchange TCP connection information. In response to this response, the relay device 15 transmits a TCP connection request to the relay device 25 (S419). Thereby, a TCP connection is established between the relay device 15 and the relay device 25.

  The above processing is dynamically processed when, for example, communication processing from the communication device 11 to the communication device 21 occurs. In other words, the relay apparatuses are not fixedly connected but are connected with the occurrence of traffic as a trigger. However, in order to prepare for a connection request from the partner relay device, the network administrator needs to log in and prepare the relay device in the network as shown in step S409. .

  In the present invention, in response to an instruction from the communication device 11, the relay device 15 transmits a SIP INVITE request via the server device 35 to establish a TCP connection (media session) for relay. That is, when a connection request from a communication device is generated, a relay path as a media session is generated using a call control protocol, so that a relay communication path can be dynamically established.

  When a TCP connection is established between the relay device 15 and the relay device 25 in this way, the relay device 15 and the relay device 25 hold the TCP connection. Then, when the communication device 11 transmits data to the communication devices 21, 22 and the like (S421), the relay device 15 relays the data to the relay device 25 (S422). The relay device 25 further relays the relayed data to the communication devices 21, 22 and the like. Similarly, data transmitted from the communication devices 21 and 22 are relayed to the relay device 15 via the relay device 25 (S423), and further relayed to the communication device 11 via the relay device 15 (S423). S424).

  When the relay transmission using the relay device 25 is completed, the communication device 11 transmits a disconnection instruction to the relay device 15 (S425). The relay device 15 transmits a disconnection request to the relay device 25 to the server device 35 (S426). The server device 35 relays this request to the relay device 25 (S427). The response from the relay device 25 is transmitted to the server device 35 (S428) and relayed to the relay device 15 (S429). As a result, the TCP connection between the relay device 15 and the relay device 25 is disconnected, and the relay device 15 notifies the communication device 11 that it has been disconnected (S430).

  In this state, when another communication device 12 makes a relay transmission request specifying the relay device 25 again (S431), a connection request is transmitted from the relay device 15 to the server device 35 (S432). If the relay device 25 is in the logout state at this point, the server device 35 notifies the logout state (S433), and notifies the communication device 12 that the partner relay device 25 is in the logout state. Similar to the processing of the communication device 11 described above, the communication device 12 makes a relay transmission request to the relay device 25 again when the relay device 25 enters the login state. Thereby, a TCP connection is established between the relay device 15 and the relay device 25.

  FIG. 8 is a flowchart focusing on the processing of the relay device 15 in the processing described in FIG. First, the relay device 15 confirms whether or not a relay instruction is generated from the communication devices 11 and 12 (step S501), and if so, confirms whether or not a state confirmation instruction is generated. (S502). If a status confirmation instruction has occurred, it is checked whether or not the relay device at the relay destination is logged in (S503). If it is determined that the relay device at the relay destination is logged out (NO in S503), the process waits until a login notification is received (S504).

  When a notification that the relay device at the relay destination is in the login state is received from the server device 35, the request source communication device is notified that the relay destination has logged in (S505). Then, it waits again until it receives a relay instruction from the communication devices 11, 12, etc. (S506). If a relay instruction is received, the process proceeds to S508. In S503, if it is determined that the relay device as the relay destination is logged in, the process immediately proceeds to S508. If the request from the communication device does not include a state monitoring instruction (NO in S502), if the relay destination is logged in (YES in S507), the process proceeds to S508, and the relay destination is logged in. If not, the process returns to S502 and repeats the process. In other words, if a status monitoring instruction is received from the request source communication terminal, monitoring is performed until the relay destination relay device logs in, and when the login status notification is received, the information is also sent to the request source communication device. Notify.

  Next, the relay device 15 generates TCP connection information (S508) and transmits a connection request (S509). Then, it waits for a response from the relay device 25 (S510), and if there is no response, notifies the requesting communication device of an error (S511), returns to S501, and repeats the processing. When the response is received, the TCP connection information in the response is analyzed (S512). That is, the port number information included in the response transmitted from the relay device 25 is acquired. Then, a TCP connection is made to the relay device 25 (S513). The request source communication apparatus is notified that the connection with the relay destination is completed (S514). Then, information on the newly created TCP connection is registered in the relay connection database 151 (S515).

  Turning to the flowchart of FIG. If relay data is transmitted from the communication device 11 or the like with the TCP connection established and held (YES in S516), the data is relayed and transmitted to the communication device 21 or the like (S517). If relay data for the communication device 11 or the like has been received (YES in S518), the data is relay-transmitted to the relay destination communication device 11 or the like (S519). When a disconnection request is received from the relay device 25 (YES in S520), a response is transmitted (S521), and the TCP connection is disconnected (S522). If a disconnection request is made by the request source communication device (YES in S523), a disconnection request is transmitted to the relay device 25 as a relay destination (S524), and if a response is received (YES in S525), TCP The connection is disconnected (S526). Then, the request source communication apparatus is notified that the connection with the relay destination has been disconnected (S527), and the TCP connection information registered in the relay connection database 151 is deleted (S528).

  As described above, according to the second embodiment, when a relay instruction is issued from a communication device, a TCP connection is dynamically established with a relay destination relay device, and communication between private networks is possible. Become. Unlike a conventional fixed VPN or the like, when a communication request occurs, a connection necessary for the communication is established, so that resources can be used efficiently.

  In the second embodiment, only a request source communication device can use a communication connection generated in response to a request from a communication device. For example, when a communication request is generated from the communication device 11 to the communication device 21 and a TCP connection is established between the relay device 15 and the relay device 25 in response to the request, the TCP connection is 11 and the communication device 21 are used only for communication. In other words, the relay device 15 and the relay device 25 relay only data transmitted and received between the communication device 11 and the communication device 21 in this TCP connection. Therefore, the connection generated by the request generated from the communication device can be occupied by the communication device.

  In the example shown in FIG. 6, it is assumed that the relay device 15 and the relay device 25 are connected by a request from the communication device 11, and that the relay device 15 and the relay device 45 are further connected by a request from the communication device 12. To do. In this case, it has been described with reference to FIG. 5 that an individual data relay connection is generated. Therefore, the communication device 11 and the communication device 12 perform relay transmission using different TCP connections. On the other hand, when the communication apparatus 11 performs relay transmission designating the relay apparatus 25 and the communication apparatus 12 also performs a relay instruction designating the same relay apparatus 25, the communication apparatus 11 is also generated in this case. Since the TCP connection is dedicated by the communication device 11, another communication connection is formed.

{Third embodiment}
Next, a third embodiment of the present invention will be described. Also in the third embodiment, similarly to the second embodiment, connection between relay devices is performed in response to a request from a communication device. However, the third embodiment is different from the second embodiment in that when a connection between relay devices is already formed, other communication devices also share the connection. In the following, differences from the second embodiment will be mainly described.

  Table 3 is a table showing a registration example of the relay connection database 151 included in the relay device 15 in the third embodiment. As shown in the table, a plurality of clients (communication devices) are associated with one TCP connection. In the example of this table, a relay transmission request is generated from two communication devices (ClientX, ClientY), and both communication devices specify the same relay device (Relayserver1@sample.net). The TCP connection is shared.

  The contents of the relay connection databases 251 and 451 included in the relay devices 25 and 45 are the same as those of the relay connection database 151 shown in Table 3. The state of the TCP connection currently established by each of the relay devices 25 and 45 is registered.

  A flow of communication processing in the communication system having the above configuration will be described with reference to FIGS. FIG. 10 is a diagram showing the overall processing flow of the communication system including the communication devices 11 and 12, the relay devices 15 and 25, and the server device 35. In the following description, communication between the relay devices 15 and 25 and the server device 35 will be described as an example using SIP (Session Initiation Protocol), but other protocols may be used. .

  In FIG. 10, the processing from step S701 to step S724 corresponds to step S401 to step S424 in FIG. That is, a relay transmission request specifying the relay device 25 is generated from the communication device 11, and a TCP connection is established between the relay device 15 and the relay device 25. Data is transmitted and received between the communication device 11 and the communication device 21 and the like.

  In such a state, another communication apparatus 12 makes a relay transmission request specifying the relay apparatus 25 again (S725). Since the TCP connection is currently established with the relay device 25, the relay device 15 notifies the communication device 12 that the data relay transmission is OK (S726). Thus, when data is transmitted from the communication device 12 (S727), the relay device 15 relays the data transmitted from the communication device 12 to the relay device 25 using the TCP connection that has already been established. Yes (S728). The relay device 25 also relays data transmitted from the communication device 21 or the like to the communication device 12 to the relay device 15 using the already established TCP connection (S729). The relay device 15 further transmits the received data to the communication terminal 12 (S730).

  As described above, in the third embodiment, when a TCP connection has already been established between relay apparatuses, and the TCP connection can be used for the generated relay transmission request, a new TCP connection is established. do not do. Multiple communication terminals share the same TCP connection. As a result, it is possible to reduce the load required for establishing a TCP connection and speed up communication between different networks. Further, it is possible to save resources of the relay device. For example, when a large number of communication terminals connected to the LAN 10 and a large number of communication terminals connected to the LAN 20 communicate via the Internet, the processing speed can be increased and resources can be saved, which is effective. . It is also effective when the amount of data relayed from one communication device is small.

  In a state where the communication device 11 and the communication device 12 perform data communication by sharing the TCP connection as described above, the communication device 11 sends a disconnection instruction to the relay device 15 (S731). Since the communication device 12 uses the same TCP connection, the relay device 15 does not particularly process the instruction in S731, but performs only a response (S732).

  Thereafter, when the relay transmission using the relay device 25 is completed, the communication device 12 transmits a disconnection instruction to the relay device 15 (S733). Since the relay device 15 has already received a disconnection instruction from the communication device 11 and can determine that the shared TCP connection is no longer necessary, the relay device 15 transmits a disconnection request to the relay device 25 to the server device 35 (S734). The server device 35 relays this request to the relay device 25 (S735). The response from the relay device 25 is transmitted to the server device 35 (S736) and relayed to the relay device 15 (S737). Thereby, the TCP connection between the relay device 15 and the relay device 25 is disconnected, and the relay device 15 notifies the communication device 11 that it has been disconnected (S738).

  FIG. 11 is a flowchart focusing on the processing of the relay device 15 in the processing described with reference to FIG. First, the relay device 15 confirms whether or not a relay instruction has been issued from the communication devices 11, 12, etc. (step S801). If a relay instruction has been issued, it is checked whether a TCP connection has already been established with the relay destination relay device (S802). That is, it is confirmed whether the same relay apparatus has already been designated by another communication apparatus and a communication is established with the relay apparatus.

  If it is already connected to the instructed relay destination (YES in S802), the request source communication apparatus is notified that data relay is possible (S815). Then, the information in the relay connection database 151 is updated (S816). That is, since the TCP connection is already registered in the database, a client (communication device) is added. In the example shown in Table 3, for example, assuming that ClientX and the TCP connection with the connection number 49583 are first registered in association with each other, processing for adding ClientY to the client field of this record is performed.

  If the connection with the relay destination designated in S802 has not been established yet, the processing of S803 to S814 is executed. This process corresponds to the processes of S502 to S513 in FIG.

  Turning to the flowchart of FIG. If relay data is transmitted from the communication device 11 or the like with the TCP connection established and held (YES in S817), the data is relayed and transmitted to the communication device 21 or the like (S818). If relay data for the communication device 11 or the like has been received (YES in S819), the data is relay-transmitted to the communication device 11 or the like that is the relay destination (S820). When a disconnection request is received from the relay destination relay device 25 (YES in S821), a response is transmitted (S822), and the TCP connection is disconnected (S823). As described above, when the TCP connection is disconnected from the relay device 25 of the relay destination, the communication device that is performing relay transmission is notified that the connection with the relay destination is disconnected (S824). When the disconnected TCP connection is shared by a plurality of communication devices, the disconnection is notified to all the communication devices (S824, S825).

  When the disconnection request is made by the request source communication device (S826), the relay device 15 checks whether the TCP connection instructed to disconnect is shared with other communication devices (S827). If it is shared with other communication apparatuses, a formal disconnection notification is sent to the instructing communication apparatus without disconnecting the instructed TCP connection (S828). Then, the information in the relay connection database 151 is updated (S829). That is, the information of the client (communication device) that requested the disconnection instruction is deleted from the information of the TCP connection that has been shared. In this way, the relay device 15 always manages the currently established TCP connection and the communication device sharing the TCP connection.

  If the TCP connection instructed to be disconnected is not shared with other communication devices (NO in S827), a disconnection request is transmitted to the relay device 25 (S830), and if a response is received (YES in S831) ), The TCP connection is disconnected (S832). Then, the request source communication apparatus is notified that the connection with the relay destination has been disconnected (S833), and the TCP connection information registered in the relay connection database 151 is deleted (S834).

  As described above, according to the third embodiment, when a relay instruction is issued from a communication device, a TCP connection is dynamically established with a relay destination relay device, and communication between private networks is possible. Become. Further, when a relay instruction is generated, if a TCP connection has already been established with the relay destination, the connection is shared. As a result, high-speed processing and effective use of resources are realized.

It is a block diagram of the communication system which concerns on 1st Embodiment. It is a figure which shows the processing flow of the communication system which concerns on 1st Embodiment. It is a flowchart which paid its attention to the relay apparatus. It is a flowchart which paid its attention to the relay apparatus. It is a figure which shows the image in which a some relay connection is established. It is a block diagram of the communication system which concerns on 2nd Embodiment. It is a figure which shows the processing flow of the communication system which concerns on 2nd Embodiment. It is a flowchart which paid its attention to the relay apparatus. It is a flowchart which paid its attention to the relay apparatus. It is a figure which shows the processing flow of the communication system which concerns on 3rd Embodiment. It is a flowchart which paid its attention to the relay apparatus. It is a flowchart which paid its attention to the relay apparatus.

Explanation of symbols

10 LAN
11 Communication device 15 Relay device 16 Gateway 20 LAN
21 Communication device 25 Relay device 26 Gateway 30 WAN
35 Server device

Claims (9)

A relay device capable of communicating with the first communication device,
Relay means for relaying data transmitted from the first communication device to another relay device;
The server device is inquired about the status of the other relay device, and when the other relay device is in a state of accepting the connection, a connection request is made to the other relay device and the connection with the other relay device is made. Holding means for dynamically establishing and holding a relay connection in
When a relay connection is established, a list of device names of communication devices connected to the LAN to which the relay device belongs is transmitted to the other relay device, and communication connected to the LAN to which the other relay device belongs. Means for exchanging a list of device names by receiving a list of device names of devices from the other relay device ;
The second communication device is connected to the LAN to which the other relay device belongs, and a data transmission request specifying the device name of the second communication device associated with the other relay device in the exchanged list as the destination Means for receiving from the first communication device;
Equipped with a,
A relay device, wherein the data transmitted from the first communication device is relayed to the other relay device, whereby the data is further relayed to the second communication device. The relay device according to claim 1,
The holding means is
Means for connecting and holding relay connections with a plurality of relay devices;
Including
The relay means is
Means for relaying data to a plurality of relay devices using a plurality of relay connections;
A relay device comprising: The relay device according to claim 2,
The holding means is
Means for individually disconnecting relay connections held between a plurality of relay devices;
A relay device comprising: The relay device according to claim 1,
  The holding means is
  Means for connecting and holding a relay connection with another relay device as specified by the communication device;
A relay device comprising:   The relay device according to claim 1,
  The holding means is
  Means for connecting and holding a relay connection with another relay device as specified by the communication device;
Including
  When a connection specification for a relay connection to a specific relay device is received from the communication device, if the relay connection is already held with the specific relay device, the relay connection already formed A relay device characterized in that it is shared. A communication system that relays data between terminals,
A first relay device capable of communicating with the first communication device;
A server device;
A second relay device capable of communicating with the second communication device;
With
The first relay device
The server device is inquired about the state of the second relay device, and when the second relay device is in a state of accepting connection, a connection request is made to the second relay device and Holding means for dynamically establishing and holding a relay connection in
When a relay connection is established, a list of device names of communication devices connected to the LAN to which the first relay device belongs is transmitted to the second relay device and connected to the LAN to which the second relay device belongs. Means for exchanging the list of device names by receiving a list of device names of the communication devices received from the second relay device ;
The second communication device is connected to the LAN to which the second relay device belongs, and the data transmission that designates the device name of the second communication device associated with the second relay device in the exchanged list as the destination Means for receiving a request from the first communication device;
Equipped with a,
The first relay device relays and transmits data transmitted from the first communication device to the second relay device, so that the second relay device further relays data to the second communication device. A communication system.   The communication system according to claim 6,
  The first communication device and the second communication device are arranged in different private networks, and an external network issues a connection request for a TCP connection to the first communication device and the second communication device. A communication system characterized by having a network configuration that cannot be performed. The communication system according to claim 6,
  The holding means is
  Means for connecting and holding a relay connection with another relay device as specified by the communication device;
A communication system comprising:   The communication system according to claim 6,
  The holding means is
  Means for connecting and holding a relay connection with another relay device as specified by the communication device;
Including
  A communication system characterized in that, when a relay connection is already formed between relay devices corresponding to a request from a communication device, the other communication devices also share the connection.

Images