JP2011147061A - Relay communication device, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To interpret an error notification from a global network even in a terminal or server which does not correspond to a call control protocol when any error is generated in a global network which corresponds to the call control protocol. <P>SOLUTION: This relay communication device is configured to connect a global network which corresponds to a call control protocol with a private network including a terminal or server which does not correspond to the call control protocol, and provided with: a session control section 503 for receiving a communication request from the terminal or server and establishing a call in a global network; and an error responding section 506 for receiving the error notification based on the call control protocol from the global network, converting it into another error notification based on a communication protocol which can be interpreted by the terminal or server, and then transmitting it to the terminal or server. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a relay communication device that connects different networks, and a communication control method using the relay communication device.

  In general, high-speed and low-cost communication is possible in a private network to which a terminal belongs, but communication in a global network that connects private networks is low-speed and high-cost. For this reason, in the global network, various systems such as a call control protocol are used to increase the speed. On the other hand, since a private network does not necessarily require strict bandwidth control, a communication method that does not support a call control protocol may be employed. Therefore, different communication methods are often employed in the private network and the global network, and a conversion device for relaying between different communication methods is required. Therefore, in a conventional communication apparatus, when a communication request from a terminal that does not support call control, for example, a connection request by TCP (Transmission Control Protocol) / UDP (User Data Protocol) arrives at the gateway apparatus, the gateway apparatus performs call control of the communication. If it is determined that the communication is to be performed, the terminal establishes a call control session suitable for the communication from the terminal and establishes the service (bandwidth or priority) established by the call control. Thus, even a terminal that does not support the call control protocol can be applied to the call control network. (For example, see Patent Document 1)

International Publication No. 2006/051594 Pamphlet (Figure 1, pages 8 to 11)

  When communication from the terminal side to the global network is performed using a conventional communication device, normally, bandwidth reservation and priority control are performed as they are by the call control protocol, but due to errors in the global network, If the error is returned to the relay communication device such as the gateway device without securing the priority control, the relay communication device can interpret the error, but the terminal that does not support the call control protocol The error cannot be interpreted. For this reason, even though an error still occurs in the global network, retransmission by the retransmission timer is repeated many times, resulting in unnecessary re-requests for communication, which may cause traffic congestion on the network.

  The present invention was made to solve the above problems, and when an error occurs in a global network that supports a call control protocol, even in a terminal or server that does not support the call control protocol, The purpose is to be able to interpret error notifications from the global network.

  A relay communication apparatus according to the present invention is a relay communication apparatus that connects a global network that supports a call control protocol and a private network that includes a terminal or server that does not support the call control protocol, and communicates from the terminal or server. When a request is received and a session control unit that establishes a call in the global network and an error notification using a call control protocol is received from the global network, the error is converted to a communication protocol error notification that can be interpreted by the terminal or server. And an error response unit to be transmitted.

  The relay communication apparatus according to the present invention is a relay communication apparatus that connects a global network that supports a call control protocol and a private network that includes a terminal or server that does not support the call control protocol, An error that brings down the link with the terminal or server when receiving a communication request signal from the server and receiving an error notification from the global network with the session control unit that establishes a call to the global network side and communicates And a response unit.

  Further, the communication control method according to the present invention includes a session control step in which the relay communication apparatus receives a communication request from a terminal or server that does not support the call control protocol, and establishes a call in a global network that supports the call control protocol; An error response step of generating an error notification of a communication protocol interpretable by the terminal or the server and transmitting the error notification to the terminal or the server when the relay communication device receives the error notification by the call control protocol from the global network. It is characterized by.

  According to the present invention, even when an error occurs in the global network, an error notification from the global network can be interpreted by a terminal or server that does not support the call control protocol.

1 is a basic configuration diagram of a network using a gateway device according to Embodiment 1 of the present invention. It is a block diagram of the gateway apparatus which concerns on Embodiment 1 of this invention. It is a sequence diagram at the time of the successful application shown in Embodiment 1 of this invention. It is a sequence diagram at the time of the occurrence of an error when the conventional gateway device shown in the first embodiment of the present invention is used. It is a block diagram of the conventional gateway apparatus shown in Embodiment 1 of this invention. It is a sequence diagram which shows the example of the error notification performed to the client terminal shown in Embodiment 1 of this invention. It is a sequence diagram which shows the example of the error notification performed to the client terminal shown in Embodiment 1 of this invention. FIG. 10 is a sequence diagram when an error occurs when a conventional gateway device is used. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 2 of this invention. It is a block diagram of the gateway apparatus which concerns on Embodiment 3 of this invention. It is a flowchart showing operation | movement of the gateway apparatus which concerns on Embodiment 3 of this invention. It is a sequence diagram which shows the example of the error notification performed to the client terminal shown in Embodiment 3 of this invention. It is a sequence diagram which shows the example of the error notification performed to the client terminal shown in Embodiment 3 of this invention. It is a sequence diagram which shows the example of the error notification performed to the client terminal shown in Embodiment 3 of this invention. It is a sequence diagram which shows the example of calculation of the retransmittable time described in the error notification shown in Embodiment 3 of this invention. It is a flowchart showing operation | movement of the gateway apparatus which concerns on Embodiment 4 of this invention. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 4 of this invention. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 4 of this invention. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 4 of this invention. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 4 of this invention. It is a sequence diagram which shows the example of the error notification performed to the server shown in Embodiment 4 of this invention. It is a sequence diagram which shows the example of calculation of the retransmission possible time described in the error notification shown in Embodiment 4 of this invention. It is a sequence diagram in the case of stopping retransmission by the client terminal due to link down shown in Embodiment 5 of the present invention. It is a sequence diagram which shows the example of the error notification at the time of using the radio | wireless communication shown in Embodiment 6 of this invention.

Embodiment 1 FIG.
FIG. 1 shows a basic configuration diagram of an IP (Internet Protocol) network using a relay communication apparatus according to Embodiment 1 of the present invention. In FIG. 1, private networks 10, 20, and 30 are connected by a global network 40, and gateway devices 50, 51, and 52 are installed between the private network and the global network. Further, client terminals 11 and 12 are arranged in the private network 10, a server 21 is arranged in the private network 20, and a server 31 is arranged in the private network 30, respectively. Here, the client terminal 11 and the server 31 do not support SIP (Session Initiation Protocol) which is a call control protocol. The global network 40 is provided with a SIP server 41 as a server via SIP.

  FIG. 2 shows a configuration diagram of the gateway device according to Embodiment 1 of the present invention. In FIG. 2, a LAN (Local Area Network) interface 501 is an interface for connecting to a LAN that is a private network, and a WAN (Wide Area Network) interface 502 is an interface for connecting to a WAN that is a global network. The session control unit 503 makes a bandwidth application to the global network 40 configured by NGN (Next Generation Network) or the like to establish a call connection. A communication protocol analysis unit 504 analyzes a protocol used for communication from a terminal or a server. The error analysis unit 505 analyzes an error notification from the global network 40. An error response unit 506 notifies an error to a client terminal or server on the private network side.

  Next, the operation of the gateway device will be described using a sequence diagram. FIG. 3 shows a sequence diagram when normal communication is performed without an error occurring in the global network. When the gateway device 50 receives a TCP SYN packet as a communication request transmitted from the client terminal 11, the communication protocol analysis unit 504 confirms the source IP address, port number, destination IP address, port number, and the like. Then, the session control unit 503 transmits an INVITE packet as a call connection request packet by SIP to the global network for bandwidth application and priority control application according to the application. When the SIP server 41 provided in the global network 40 receives the INVITE packet from the gateway device 50, the SIP server 41 transfers the INVITE packet to the destination gateway device 51. At this time, the SIP server 41 returns a preparation response message 100 Trying message to the gateway device 50. The gateway device 51 that has received the INVITE packet transferred from the SIP server 40 sends 100 Trying indicating that the INVITE packet has been received and 200 OK, which is an acceptance response to the INVITE packet, to the SIP server 41. When the application by SIP is completed, the TCP SYN packet that has been waiting in the gateway device 50 is transferred to the destination server 21 using the bandwidth and priority control secured by the SIP, and the server 21 that has received the TCP SYN Returns SYN / ACK. The client terminal 11 that has received SYN / ACK returns ACK, and a TCP session is established between the client terminal 11 and the server 21. Once the application is completed through the SIP session, the operation is the same as normal communication, and the client terminal 11 starts communication such as HTTP GET.

  Next, the operation of the gateway device when an error occurs in the global network will be described. Here, an error in the global network refers to a case in which a signal transmitted from the private network does not reach the destination gateway device for some reason. For example, a global network failure or a communication flow temporarily increases, This is a case where the simultaneous application is restricted and the communication request from the private network to the global network is rejected.

  FIG. 4 is a sequence diagram when a conventional gateway device is used. FIG. 5 shows the configuration of a conventional gateway device. 5, the same reference numerals as those in FIG. 2 denote the same or similar parts. A TCP SYN packet as a TCP communication request arrives at the gateway device 50 from the client terminal 11, and the gateway device 50 analyzes the communication request by the communication protocol analysis unit 504. Based on the analysis result, the session control unit 503 transmits an INVITE packet as a call connection request by SIP to the global network 40 and applies for bandwidth and priority control. However, because an error has occurred in the global network 40, the application failed and a 4xx request error, which is a SIP error notification, is returned to the gateway device 50. The gateway device can interpret the SIP error notification. However, since the client terminal does not support SIP, the error notification cannot be interpreted. For this reason, error notification is not sent to the client terminal, and the communication request is retransmitted many times by the retransmission timer, and an unnecessary communication request is generated.

  FIG. 6 is a sequence diagram when an error occurs in the global network when the gateway device according to the first embodiment of the present invention is used. As in the case of using the conventional gateway device shown in FIG. 4, a SIP error notification is returned from the global network 40 in response to the SIP application transmitted from the gateway device 50. In the gateway device according to the first embodiment, the error analysis unit 505 reads the received SIP error notification, reads the content, for example, a message such as a response code or Retry After included in the error notification, and the error in the global network. Is notified to the error response unit 506. Upon receiving the notification, the error response unit 506 converts the SIP error notification received from the global network into a TCP RST and transmits it to the client terminal 11 as an error notification. Since the TCP RST can be interpreted by a client terminal that does not support SIP, the client terminal 11 that has received the TCP RST stops communication and does not cause retransmission.

  Since the gateway device according to the first embodiment has the above-described configuration, even if the client terminal that requests communication does not support the call control protocol, an error notification on the global network side is sent. As a result, it is possible to recognize the unnecessary communication re-request.

  Here, a case where the gateway device 40 returns a TCP RST to the client terminal 11 has been shown, but as shown in FIG. 7, an ICMP (Internet Control Message Protocol) Network Unreachable which is an error message by IP is returned. Then, it is possible to stop communication from the client terminal 11 and prevent retransmission of the communication request.

  Further, although a case where a gateway device is used as a relay communication device has been described, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Furthermore, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used. Moreover, although the case where the error notification for stopping the retransmission of the communication request is performed to the client terminal has been described, when the client terminal is connected to a plurality of networks, it is based on a different network (for example, a wireless communication network). An error notification to be changed to communication may be used.

Embodiment 2. FIG.
In the first embodiment, the case where the communication request is transmitted from the client terminal is shown. However, in the second embodiment, the case where the communication request is transmitted from the server side is shown. A basic configuration diagram of an IP network using the gateway device according to the second embodiment of the present invention is the same as that of the first embodiment, as shown in FIG. The configuration of the gateway device according to the second embodiment of the present invention is the same as that of the gateway device according to the first embodiment, as shown in FIG.

  FIG. 8 shows a sequence diagram when a conventional gateway device is used. When the server 31 transmits an RTP (Real-time Transport Protocol) packet used for moving images or the like to the client terminal 12 and reaches the gateway device 52, the gateway device 52 is the same as in the first embodiment. The source and destination IP addresses and port numbers are analyzed, and an INVITE packet as a SIP call connection request is transmitted to the global network 40. However, there is an error in the global network, and a SIP error notification 4xx request error is returned to the gateway device. The gateway device 52 can interpret the SIP error notification. However, since the server 31 does not support SIP, the error notification cannot be interpreted. Therefore, no error notification is sent to the server 31, and RTP packets are always transmitted from the server.

  FIG. 9 is a sequence diagram when an error occurs in the global network when the gateway device according to the second embodiment of the present invention is used. As in the case shown in FIG. 8, a communication request and a call connection request are transmitted, and an error notification 4xx request error is returned due to an error in the global network. The gateway device 52 that has received the error notification analyzes the error notification received by the error analysis unit 505, and returns a Network Unreachable that is an error notification by IP to the server 31 by the error response unit 506 based on the analysis result. This error notification is an error notification that can be interpreted even by a server 31 that does not support SIP, and the server 31 that has received the error notification stops communication from the server.

  Since the gateway device according to the second embodiment is configured as described above, it recognizes an error on the global network side even when the server that requests communication does not support the call control protocol. Thus, it is possible to make a judgment at the time of an error similar to normal communication. Therefore, there is an effect that unnecessary communication re-request is not performed.

  Here, a case where a gateway device is used as a relay communication device has been described. However, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Also, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used. Furthermore, the case where an error notification for stopping the retransmission of the communication request is given to the server has been shown. However, when the server is connected to a plurality of networks, the communication is performed by a different network (for example, a wireless communication network). An error notification to be changed may be used.

Embodiment 3 FIG.
In the first embodiment, when the gateway apparatus receives an error notification, the same error notification is returned regardless of the communication method of the client terminal. However, in the third embodiment, an error is generated according to the communication method of the client terminal. A method for changing the type of notification will be described. The basic configuration diagram of the IP network using the gateway device according to the third embodiment of the present invention is the same as that of the first embodiment, as shown in FIG.

  FIG. 10 shows the configuration of the gateway device according to the third embodiment. In FIG. 10, the timer calculation unit 507 calculates the retransmittable time of the communication request after stopping communication due to an error response. The same reference numerals as those in FIG. 2 denote the same or similar parts.

  FIG. 11 is a flowchart showing the operation of the gateway device according to Embodiment 3 of the present invention. A TCP communication request is generated by the client terminal 11 (step S1), and the gateway device 50, which is a relay communication device existing between the private network and the global network, receives this communication request (step S2). Upon receiving the communication request, the gateway device 50 interprets the content of the communication request by the communication protocol analysis unit 504, and uses the communication request as a trigger to apply a bandwidth application by SIP to the global network 40 by the session control unit 503. Priorities are applied (step S3). In step S4, the session control unit 503 determines whether or not the SIP application is successful. If the SIP application is successful, the process proceeds to step S5. In step S5, as in the case shown in FIG. 3, the communication request is transferred to the global network side, and normal communication is started with the applied service applied.

  On the other hand, when an error occurs in the global network, when the SIP application fails and an error notification is returned from the global network side, the gateway device 50 returns a provisional response to the communication request to the client terminal 11 (step S6). The client terminal 11 that has received the provisional response then starts communication of an application such as HTTP (step S7). The gateway device receives the communication of this application (step S8), and analyzes the type of communication received by the protocol analysis unit 504 (step S9). Based on the analysis result, the error response unit 506 changes the response type in accordance with each communication method, and returns an error notification to the client terminal 11 that has made the communication request. Thereby, notification according to the communication method from the client terminal can be performed, and detailed error notification such as retransmission possible time can be performed. Here, if a notification is received from the global network about the response time when performing error notification, the error notification is also added and responded (steps S10 to S13).

  FIG. 12 is a sequence diagram when the client terminal 11 accesses the server 21 using HTTP as a communication method. When a TCP SYN packet as a communication request arrives from the client terminal 11 to the gateway device 50, the gateway device 50 receives it and sends an INVITE packet as a SIP call connection request to the global network 40 to apply for a bandwidth and the like. I do. When an error occurs in the global network 40 and the SIP error notification 4xx request error is returned from the global network 40, the gateway device 50 causes the error analysis unit 505 to send the error notification content, for example, a response code included in the error notification. And a message such as Retry After, and the read content is notified to the error response unit 506. The error response unit 506 that has received the notification returns a TCP SYN / ACK as a provisional response to the client terminal 11. The client terminal 11 that has received the provisional response starts communication using HTTP such as HTTP GET, and the gateway device 50 receives this communication. The gateway device 50 uses the communication protocol analysis unit 504 to analyze the communication method of communication from the client terminal 11 and notifies the error response unit 507 of the analyzed communication method. When the communication method is HTTP, HTTP communication from the client terminal 11 does not pass through the global network 40. As a response, the error response unit 507 sends a SIP error notification to the HTTP error notification (503 Service). (Unavailable) and return to the client terminal 11.

  Here, the error analysis unit 505 notifies the error response unit 506 of the time when SIP reception time is described in the error notification from the global network 40. The error response unit 506 describes the time in the error notification by HTTP and returns an error notification to the client terminal 11. On the other hand, when there is no description of the SIP reception time, the timer calculation unit 507 is notified of the content of the error notification from the global network 40, and the timer calculation unit 507 calculates based on the content of the error notification from the global network 40. The reconnect request possible time is described in the error notification, and the error notification is returned to the client terminal 11 (steps S10b to S13b). Here, by describing Retry-After that sets the reconnection request time in the 503 Service Unavailable message, an error notification in which the reconnection request time is set can be performed. Further, the content of the error notification is a SIP response code, and is defined as, for example, 400 Bad Request. The time until reconnection can be set according to the content of the error notification. Thereby, it is possible to notify the client terminal of the reconnection request time according to the content of the error that has occurred in the global network, and efficient communication can be performed.

  The client terminal 11 can interpret the HTTP error notification, and transmits a FIN packet to disconnect communication with the gateway device 50. Then, reconnection is attempted after the time described in Retry-After. In FIG. 12, Retry-After 30 is set in the error notification by HTTP, and the client terminal 11 receiving the error notification retransmits the communication request 30 seconds after receiving the error notification. At the time of retransmission of the communication request, the error in the global network has been eliminated, and a TCP session can be established and HTTP communication can be performed as in the case shown in FIG. 3 of the first embodiment.

  Although FIG. 12 shows the case where the time until reconnection is described in the 503 Service Unavailable Retry-After from the gateway device 40, as shown in FIG. 13, the GMT (Greenwich Mean Time) time is described. May be. By describing the GMT time, the client terminal attempts to reconnect at that time.

  Next, a case where FTP (File Transfer Protocol) is used as a communication method will be described. FIG. 14 shows a sequence diagram when the client terminal 11 accesses the server 21 using FTP as a communication method. 14, when an FTP communication request is generated from the client terminal 11, the gateway device 50 transmits an INVITE packet as a SIP call connection request to the global network 40 as in the case of the HTTP communication illustrated in FIG. 12. Apply for bandwidth and priority control. When there is an error notification from the global network 40, the gateway device 50 returns a TCP SYN / ACK to the client terminal as a provisional response by TCP. The client terminal 11 that has received the provisional response from the gateway terminal 50 performs FTP communication. The gateway device 50 analyzes the communication from the client terminal 11 in the communication protocol analysis unit 504 (step S9). If it is recognized that the communication from the client terminal 11 is based on FTP, the response code 120 is returned to the client terminal 11 for the communication based on FTP (step S13a). Here, if there is a description of the SIP reception time in the error notification from the global network, that time is designated in the response code 120, and if not, the retransmittable time calculated by the timer calculation unit 507 is designated in the response code 120 (step S11a, S12a) By notifying the client terminal 11 how many minutes later the server can be prepared, it becomes possible to simultaneously stop requests from the client terminal. In FIG. 14, “Service ready in 5 minutes” is set, and the communication request is retransmitted 5 minutes after the response code 120 is received. When the communication request is retransmitted, the error in the global network 40 is eliminated, and a TCP session is established and FTP communication is performed as in the case shown in FIG. 3 of the first embodiment.

  Further, when communication is performed using a communication method other than FTP and HTTP, as in the case of the first embodiment, a TCP RST that can be interpreted by a terminal that does not support SIP is returned (step S13c). ).

  FIG. 15 is an example of a method for calculating the time until reconnection (Retry-After) in the timer calculation unit 507. In a system using SIP, the time from the end of communication to the disconnection of the SIP connection is not immediate, and may end after waiting for a certain time. Here, as a restriction on the global network side, it is assumed that only a certain number of applications by SIP are accepted. The TCP FIN packet is transmitted from the client terminal 11, and the TCP FIN / ACK and ACK packets, which are response messages, are returned from the gateway device 50 and the client terminal 11, respectively, and the existing communication ends. Then, BYE is transmitted by the gateway device 50 after a predetermined time has elapsed, and transferred to the destination gateway device 52 by the SIP server 41. When the gateway device 52 and the SIP server 41 return 200 OK, the SIP connection is disconnected. In the meantime, if another new communication occurs, the new communication is rejected by the global network 40 and an error notification is returned. Receiving the error notification, the gateway device 50 calculates the time until the SIP application for the existing communication is disconnected to the client terminal 11 by using Retry-After, and notifies it. The time until the retransmission in FIG. 15 is the preset time (Y in FIG. 15) from the transmission of the FIN packet indicating the end of the communication to the BYE that actually disconnects the SIP application, Is calculated from the elapsed time (X in FIG. 15) from the transmission of the FIN packet in the communication performed to the gateway terminal returning an error notification to the client terminal, and the time until the communication request is retransmitted (FIG. 15). Z) in 15 is obtained by Z = YX. By notifying the client terminal 11 of the determined time Z, the communication request can be retransmitted after that time. Note that it is possible to shift the notification time by Retry-After by several seconds in consideration of some processing difference.

  In addition, when the user of the client terminal performs communication using the browser (HTTP) and an error is returned from the global network, the current status (error status and It may be possible to display a Retry-After information indicating how many seconds later to return, and to reconnect to the user himself / herself.

  Since the gateway device according to the third embodiment of the present invention has the above-described configuration, it notifies an error corresponding to the communication method even to a client terminal that does not support the call control protocol. In addition, it is possible to notify the retransmittable time of the communication request. As a result, efficient communication is possible without re-requesting unnecessary communication.

  Here, a case where a gateway device is used as a relay communication device has been described. However, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Also, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used.

  Also, here, a method of returning a provisional response to the client terminal from the gateway apparatus that has received the error notification has been described. Steps S6 to S8 in the flowchart can be omitted. Thereby, although the detailed content of the communication from the client terminal cannot be analyzed, the communication from the client terminal can be reduced.

Embodiment 4 FIG.
In the third embodiment, a case where a communication request is transmitted from a client terminal is shown. However, in a fourth embodiment, a case where a communication request is generated from a server is shown. A basic configuration diagram of an IP network using the relay communication apparatus according to the third embodiment of the present invention is the same as that of the first embodiment, as shown in FIG. The configuration of the gateway device is the same as that of the third embodiment and is as shown in FIG.

  FIG. 16 is a flowchart when communication by the UDP from the server 31 to the client terminal 12 occurs. When a new communication request by UDP is generated from the server 31 accommodated in the private network 30 (step S1), the gateway device 52 existing between the private network 30 and the global network 40 receives this communication (step S1). S2). The gateway device that has received this new communication interprets the contents of the communication (destination IP address, destination port number, transmission source IP address, transmission source port number, etc.), and applies to the global network 40 for SIP bandwidth application and priority. Application is performed (step S3). In step S4, it is determined whether or not the SIP application is successful. If the SIP application is successful, the process proceeds to step S5, and communication is performed in a state where the service for which new communication is applied is applied as usual.

  On the other hand, when the SIP application fails and an error is returned from the global network side, the gateway returns an RTSP (Real Time Streaming Protocol) message / RTCP (Real-time Transport Control Protocol) response to the server. At that time, if the SIP reception time is notified from the global network 40, the time is added to the message. If not, the retransmission response time is calculated, and the calculated time is added to the message. And responds (steps S10d to S13d).

  FIG. 17 is a sequence diagram when communication by RTP is performed from the server 31 to the client terminal 12. When the RTP packet arrives at the gateway device 52 from the server 31, the gateway device 52 transmits an INVITE packet as a SIP call connection request, and applies for a bandwidth and the like. When an error occurs in the global network and an error notification is returned, the error analysis unit 505 of the gateway device 52 analyzes the error content and notifies the error response unit 506 of the error content, as shown in FIG. To do. The error response unit 506 returns an RTSP ANNOUNCE method to the server 31. Here, when the SIP reception time is described in the error notification from the global network 40, the error analysis unit 505 notifies the error response unit 506 of the time, and the error response unit 506 notifies the error notification of the time. And an error notification is sent to the server 31. On the other hand, when there is no description of the SIP reception time, the timer calculation unit 507 is notified of the content of the error notification from the global network 40, and the timer calculation unit 507 calculates based on the content of the error notification from the global network 40. The time during which reconnection can be requested is described in the error notification, and an error notification is sent to the server 31 (steps S10b to S13b). The description of the retransmission response time is performed by designating the t line in the SDP (Session Description Protocol) of the ANSPUNC method of RTSP and designating the start time. This error notification can be interpreted even by a server that does not support SIP, stops communication by RTP, and starts re-communication from the server at the start time. At this time, the ANNOUNCE method stops the target RTP packet by designating the port number that transmits the server's RTP packet. In this example, the ANNOUNCE method is used, but any RTSP message that can specify the t-line of SDP may be used.

  FIG. 17 shows a case where an RTSP ANNOUNCE method is returned as an error notification. However, in FIG. 18, when RTP communication is performed from the server to the client terminal 11, the RTSP PAUSE method is used. A method for stopping communication will be described. When an error is returned from the global network 40 to the gateway device 51, an RTSP PAUSE method is sent to the server 31 to stop the RTP packet from the server and apply to the global network 40. Then, communication from the server 31 is resumed using the PLAY method of RTSP. In this case as well, the RTSP port number is designated as the port number on which the RTP of the server 31 is flowing.

  As in FIG. 17, FIG. 19 uses RTSP ANNOUNCE as an error notification. In FIG. 19, by specifying line b in the SDP of the RTSP ANNOUNCE method and setting the usage bandwidth to 0.0 (b = 0.0), it is shown that the usage bandwidth is small relative to the server. 31 is urged to stop communication. When restarting, a value greater than 0 is entered in the b line of the ANNOUNCE SDP to prompt the restart of communication again. FIG. 19 shows a case where the b line of the ANNOUNCE SDP at the time of restart is 1.0. In this example, the ANNOUNCE method is used, but any RTSP message that can specify the b line of SDP may be used.

  In the RTSP message, it is determined which message the response is based on the Cseq number. When the gateway device 52 independently transmits an RTSP message to the server 31, there is a possibility that the Cseq number between the client terminal 12 and the server 31 is shifted. Therefore, by terminating the RTSP message once in the gateway device 50 or 52 and changing the Cseq number and then sending it to the server 31, communication can be performed without any problem even when the Cseq number is shifted. FIG. 20 shows a sequence diagram when the Cseq number is changed by the gateway device 52. In FIG. 20, as in the case shown in FIG. 19, a UDP connection is established by retransmission of RTP, and an RTSP message is transmitted from the client terminal 12 with Cseq = 1. The gateway device 52 that has received the RTSP message terminates this message, replaces it with Cseq = 100, and transmits it to the server 31. The gateway device that has received the response from the server 31 terminates this message, changes it to Cseq = 100, and transmits it to the client device 12.

  FIG. 21 shows a sequence diagram when an error notification is returned from the gateway device by RTCP RR (Receive Report) which is a standard RTP response. When RTP communication occurs from the server 31 and an error notification is received from the global network 40, the gateway device 52 notifies the server 31 of a missing rate of 100% by RTCP RR, which is a standard RTP response. To do. This suggests that the packet does not reach the server 31 to the global network side, and suppresses RTP communication from the server side. When resuming communication, the RTCP RR notifies the missing rate of 0%, which suggests that the server 31 can transmit packets to the global network side.

  FIG. 22 is an example of a method for setting the time until reconnection to the server 31 (in FIG. 22, the t line of the RTSP message is used). As in the case shown in FIG. 15, if another new communication request is generated within a certain period of time until the existing communication from the server 31 is terminated and the SIP application is actually disconnected, the global network 40 Communication is rejected and an error notification is returned. The gateway device 52 that has received the error notification sets the set time such as the t row of the RTSP message to be notified to the server as the elapsed time from the last RTP packet arrival time of other communication to the current time (X in FIG. 22). ) And the time from the last RTP packet of the gateway device to the BYE transmission (Y in FIG. 22) set in advance, and the set time for the start time is set to the current time + (Y−X) And notify it. In consideration of some processing difference, the notification time in t rows or the like may be shifted by several seconds.

  Since the gateway device according to the fourth embodiment of the present invention has the above-described configuration, even a server that does not support the call control protocol can be notified of an error according to the communication method. In addition, by notifying the retransmittable time of the communication request, efficient communication is possible without performing unnecessary communication re-request.

  Here, a case where a gateway device is used as a relay communication device has been described. However, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Also, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used.

Embodiment 5 FIG.
In the third embodiment, a method has been described in which the gateway device that has received the error notification performs an error notification that can be interpreted by the client terminal to the client terminal. However, in the fifth embodiment, the gateway device that has received the error notification A method for bringing down the link with the client terminal will be described. The basic configuration diagram of the IP network using the gateway device according to the third embodiment of the present invention is the same as that of the first embodiment, as shown in FIG. The configuration of the gateway device according to the fifth embodiment is the same as that of the first embodiment and is as shown in FIG.

  FIG. 23 is a sequence diagram when the gateway apparatus that has received the error notification brings down the link with the client terminal. In FIG. 23, the gateway device 50 transmits a TCP RST to the client terminal 11 in response to an error notification from the global network, as in the case shown in FIG. 6 in the first embodiment. After transmitting the TCP RST, the gateway device 50 causes the error response unit 506 to link down the physical port corresponding to the client terminal 11. Since the link is down, communication from the client terminal 11 does not occur. When the SIP application to the global network 40 becomes possible, the gateway device 50 re-accepts the request from the client terminal 40 by raising the link that has been linked down, as shown in FIG. A TCP connection is established and communication is performed. This method can be similarly performed not only on the client terminal side but also between the server 31 and the gateway device 52.

  In the gateway device according to the fifth embodiment of the present invention, since it is configured as described above, even if the client terminal does not support the call control protocol, it does not perform unnecessary communication re-requests. An effect is obtained.

  Here, a case where a gateway device is used as a relay communication device has been described. However, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Also, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used.

Embodiment 6 FIG.
In the fifth embodiment, the case where wired communication is used has been described, but in the sixth embodiment of the present invention, a method using wireless communication will be described. The configuration of the gateway device according to the sixth embodiment is the same as that of the first embodiment, as shown in FIG.

  FIG. 24 shows an example in which wireless communication is used between the client terminal 11 and the gateway device 50. As in FIG. 23, the communication from the client terminal is refused and the communication from the client terminal is generated by changing the SSID (Service Set Identifier) that is the identifier of the access point in the wireless LAN in the sense of performing the link down. Do not let it. After the application becomes ready for the global network 40 again, the SSID from the client terminal 11 is changed back to the original, and the request from the client terminal 11 is accepted again. Then, similarly to the case shown in FIG. 3, a TCP connection is established and communication is performed. This method is the same not only on the client side but also between the server side 31 and the gateway device 52.

  Since the gateway device according to Embodiment 6 of the present invention has the above-described configuration, useless communication is possible even when the client terminal does not support the call control protocol in a network using wireless communication. The effect of not implementing the re-request is obtained.

  Here, a case where a gateway device is used as a relay communication device has been described. However, the same effect can be obtained even in a device (for example, a router) that can relay an IP packet in addition to the gateway device. Also, the case where SIP is used as the call control protocol has been shown. Protocols such as H.323 and MGCP may be used.

10 private network, 11, 12 client terminal, 20 private network, 21 server terminal, 30 private network, 31 server terminal, 40 global network, 41 SIP server, 50-52 gateway device, 501 LAN interface, 502 WAN interface, 503 session Control unit, 504 Communication protocol analysis unit, 505 Error analysis unit, 506 Error response unit, 507 Timer calculation unit

Claims (7)

A relay communication device that connects a global network corresponding to a call control protocol and a private network including a terminal or a server not corresponding to the call control protocol,
A session control unit that receives a communication request from the terminal or server and establishes a call in the global network;
When an error notification by the call control protocol is received from the global network, an error response unit that converts the error notification of a communication protocol that can be interpreted by the terminal or server and transmits the error notification to the terminal or server;
A relay communication device comprising:   The relay communication apparatus according to claim 1, wherein the error response unit notifies the terminal or the server of an error for stopping retransmission of a communication request signal.   The relay communication apparatus according to claim 2, wherein the error response unit notifies the terminal or server of a time during which a communication request signal can be retransmitted. A preset time from the end of communication of the terminal or server until a call disconnection request in the global network occurs; and
From the end of communication of the terminal or server until the error response unit receives an error notification from the global network,
The relay communication apparatus according to claim 3, further comprising a timer calculation unit that calculates the retransmittable time. The error notification from the global network includes error information indicating the content of the error,
The error response unit notifying the retransmittable time based on the error information;
The relay communication apparatus according to claim 3. A relay communication device that connects a global network corresponding to a call control protocol and a private network including a terminal or a server not corresponding to the call control protocol,
A session control unit that receives a communication request signal from the terminal or server, establishes a call to the global network side, and performs communication;
When receiving an error notification by a call control protocol from the global network, an error response unit that brings down the link with the terminal or server;
A relay communication device comprising: A session control step in which the relay communication device receives a communication request from a terminal or server that does not support the call control protocol, and establishes a call in the global network corresponding to the call control protocol;
When the relay communication device receives an error notification by a call control protocol from the global network, an error response step of generating an error notification of a communication protocol interpretable by the terminal or server and transmitting the error notification to the terminal or server;
A communication control method comprising:

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