JP2009296419A - Communication relay apparatus, communication system, communication method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication relay apparatus that carries out an address translation relating to real-time Internet FAX communication specified in the ITU-T recommendation T.38. <P>SOLUTION: A communication relay apparatus 20 includes: a processing means 108 which is connected to both a first network 36 of a first address space, where a first communication device is connected, and a second network 40 of a second address space, where a second communication device is connected, and performs relay processing upon a message exchanged between the communication devices in accordance with a call control protocol of FAX communication; a determination means 110 for determining a relay address to be used for relay between the networks for a communication channel to be used for transmitting FAX data of FAX communication; a rewriting means 112 for rewriting an address of the communication channel contained in a message received from a communication device into the relay address on the corresponding address space; and a registration means 114 for registering a permission of relay of FAX data via a communication channel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to address translation technology, and more particularly, to ITU-T Recommendation T.30. The present invention relates to a communication relay apparatus, a communication system, a communication method, and a program for performing address conversion related to real-time Internet facsimile (hereinafter referred to as facsimile) as defined in H.38.

  In recent years, with the broadbandization of the Internet, a FAX apparatus having a real-time Internet FAX communication function that realizes FAX communication in real time via the Internet is becoming widespread (Patent Document 1). ITU-T recommendation The Internet FAX conforming to the standard 38 is the same as the recommendation T.37. The Internet FAX conforming to 37 is referred to as a storage type because it transmits data via a mail server, whereas it is referred to as a real-time type because it directly transmits data while connected to a partner device in the same way as G3 FAX. ing.

  In this real-time type Internet FAX, capability exchange and delivery confirmation can be performed immediately, and functions equivalent to those of FAX communication via a conventional PSTN (Public Switched Telephone Networks) can be realized. In the real-time Internet FAX, call control is performed according to ITU-T recommendation H.264. It is performed using a protocol stack conforming to H.323 or SIP (Session Initiation Protocol) of the IETF standard. In addition, MGCP (Media Gateway Control Protocol) is also recommended as a protocol used for call control.

  In the real-time Internet FAX, the port number used in the data communication channel for transmitting actual FAX data is dynamically determined by the call control protocol. There is a problem that NAT (Network Address Translation) for performing address exchange for connecting to a network cannot be transmitted.

  As a technique for coping with a problem caused by address conversion in such network communication, the above-mentioned Japanese Patent No. 3875453 (Patent Document 1) is connected to a packet network, and the ITU-T recommendation T.264. 38, when it is detected that the counterpart device supports data transfer using the call control channel in the network FAX that exchanges FAX messages with the counterpart device via the packet network according to the procedure based on No. 38. A network FAX apparatus comprising a communication control means for performing data transfer with a partner apparatus using a call control channel without establishing a new data channel is disclosed.

  In addition, for example, Japanese Patent Laid-Open No. 2006-246385 (Patent Document 2) stores a conversion table in which a transmission destination address and a transmission source address are associated with each other in advance in a storage device and receives data from a server via a global network. The source address included in the received data is extracted, the destination address corresponding to the source address is extracted from the conversion table, and the data is relayed to the client indicated by the destination address via the private network. A routing device is disclosed.

  Japanese Patent Laid-Open No. 2000-341337 (Patent Document 3) is a system for connecting private networks via the Internet, provided in each private network, having an IP masquerade function, and connecting to the Internet Sometimes, a plurality of reserved host names of terminals that are required to be connected in advance, a plurality of internal reserved port numbers corresponding to each of the reserved host names, and a port number reservation table that holds in common among the routers, The internal reserved port number is used as the source port number. On the other hand, when connecting to the private network, the reserved host name is obtained from the internal reserved port number used as the source port number of the packet by referring to the port number reservation table. A route that recognizes and passes the packet to the terminal with the recognized reserved host name. It discloses a system comprising a.

Further, Japanese Patent No. 3522118 (Patent Document 4) has a registration table for registering the IP address of the computer in the own station, the telephone number of the corresponding telephone of the computer, and the receivable state of the computer. If the destination address included in the phone number is a telephone number in the local station, the IP address of the computer corresponding to the telephone number is obtained by searching the registration table, and the IP address is obtained when the computer is in a receivable state. An IP telephone gateway device is disclosed, which performs outgoing processing to a computer having an IP address. In addition, Japanese Patent No. 3501269 (Patent Document 5) is characterized by changing a timer value which is a normal maximum response time of a signal received from a counterpart facsimile machine when a packet delay occurs in a packet network. Is disclosed.
Patent No. 3875453 JP 2006-246385 A JP 2000-341337 A Japanese Patent No. 3522118 Patent No. 3501269

  The prior art disclosed in Patent Document 1 also executes data transfer using the channel used for call control without establishing a data channel separately in order to improve the transparency in the firewall and NAT. It is to try. However, both facsimile apparatuses need to support data transfer using a call control channel, which is not sufficient from the viewpoint of versatility.

  Moreover, although the conventional techniques disclosed in the above-mentioned Patent Documents 2 to 5 extend the NAT technique, the recommendations T. In communications conforming to US Pat. No. 38, it was not possible to establish a data channel that uses a port number determined by a call control protocol across the NAT. Further, in the above prior art, it is difficult to maintain stable facsimile communication when the load increases due to multiplex communication.

  The present invention has been made in view of the above problems, and makes it possible to establish a communication channel used for transmitting facsimile data of facsimile communication between communication devices connected to networks in different address spaces. An object of the present invention is to provide a communication relay device, a communication system, a communication method, and a program.

  In the present invention, in order to solve the above problems, the communication relay device relays messages exchanged between the communication devices in accordance with a call control protocol of facsimile communication. At that time, the communication relay apparatus determines a relay address to be used for relaying between networks for the communication channel used for facsimile data transmission of the facsimile communication, and determines the communication channel included in the message received from each communication apparatus. The address is rewritten to the relay address in the corresponding address space. Then, the communication relay device registers permission for relaying facsimile data via the communication channel.

  With the above configuration, since the address included in the message conforming to the call control protocol is rewritten, between the first communication device of the first network in the first address space and the second communication device of the second network in the second address space. Thus, regardless of the difference in address space, it is possible to establish a transmission path for facsimile data via a communication relay device corresponding to the relay address. Further, since the transmission path can be established even if the network address space to which the communication devices at both ends are connected is different, facsimile communication with high security is possible.

  In the present invention, at least one data communication relay device connected to both the networks is provided, and the relay address can be determined by referring to a table in which the address of the data communication relay device is registered. This data communication relay device can register channel configuration information at both ends for a communication channel and relay corresponding packets. Since transmission of facsimile data including image information is distributed to other data communication relay devices, the load is distributed, and highly stable facsimile communication is possible.

  Further, in the present invention, the relay address can be determined according to the number of relays maintained by each communication relay device, whether the communication device is a gateway device or a direct connection type facsimile device, a communication channel May be determined in consideration of whether it is configured by a UDP port or a TCP port.

  With a configuration in which a relay channel is determined according to the number of relays maintained, a relay address of a communication relay device with a relatively small load is selected during call control, and highly stable facsimile communication is possible. . In addition, it is a communication and connectionless protocol including gateway devices that are prone to packet delay and loss, and has a relatively low load in advance for communication that uses UDP, which is also prone to packet delay and loss, as a transport layer protocol. It is possible to select a communication relay device from the group set as described above, and more stable facsimile communication is possible.

  Hereinafter, although it demonstrates using embodiment of this invention, embodiment of this invention is not limited to the following embodiment.

  FIG. 1 is a schematic diagram illustrating an embodiment of a network environment. A network environment 10 shown in FIG. 1 includes an Internet 36 for interconnecting nodes using an appropriate transport layer / network layer protocol such as TCP (Transmission Control Protocol) / IP (Internet Protocol), for example, Ethernet (registration). And an internal network 40 configured as a local area network (hereinafter referred to as a LAN).

  The network environment 10 is further connected directly to the Internet 36, and the ITU-T recommendation T.30. 38, a direct connection type Internet FAX apparatus (Internet Aware Fax: hereinafter referred to as an IAF apparatus) 38 that executes FAX image communication conforming to the standard 38, and a multi-function device 42 that is connected to the internal network 40 and similarly executes FAX image communication. And T. And a G3 FAX device 48 connected to the internal network 40 via a 38 gateway device 44 and a telephone network 46. T.A. The 38 gateway device 44 is a device that connects a FAX device that performs communication via a telephone network such as G3 to the packet network.

  In the network environment 10 of the present embodiment, a node connected to the Internet 36 is assigned a global IP address that is managed by an IANA (Internet Assigned Numbers Authority) and uniquely identified on the Internet 36. On the other hand, a node connected to the internal network 40 is assigned a private IP address that uniquely identifies the node on the internal network 40.

  A network address translation (NAT) server group 12 constituting a communication system is installed between the Internet 36 and the internal network 40. The NAT server group 12 is a network between the addresses on the global IP address space of the Internet 36 and the addresses on the private IP address space of the internal network 40. 38, address translation processing related to communication is executed, and packet transmission across networks is relayed. In the present embodiment, the NAT server group 12 statically associates the private addresses of the MFP 42 and the gateway device 44 on the internal network 40 with the global address. These FAX apparatuses are configured to be able to receive calls from outside the internal network 40.

  More specifically, the NAT server group 12 includes T.D. 38, the call control server 20 that exclusively relays messages related to call control, and the data communication server 30-1 to the data communication server that exclusively relays IFP (Internet Facsimile Protocol) packets of data channels that transmit FAX data 30-N (hereinafter referred to as the data communication server 30 except when a specific server is specified).

  The call control server 20 is configured to include two NICs: a network interface card (hereinafter referred to as a NIC) 22 connected to the Internet 36 and a NIC 24 connected to the internal network 40. Similarly, each data communication server 30 is configured to include two NICs: a NIC 32 connected to the Internet 36 and a NIC 34 connected to the internal network 40. Each of the NICs 22 and 32 and the NICs 24 and 34 is assigned a global IP address and a private IP address, respectively.

  In the NAT server group 12 of the present embodiment, a packet transmitted from the Internet 36 to a node of the internal network 40 or a packet directed from the internal network 40 to the Internet 36 is routed so as to pass through the call control server 20. ing. On the other hand, the data transfer server 30 is connected to the T.C. It is configured to relay an IFP packet in FAX communication conforming to H.38. By the relay of the NAT server group 12, a data channel for transmitting an IFP packet is established from the Internet 36 to the internal network 40 or from the internal network 40 to the Internet 36.

  Although not shown in FIG. 1, address resolution between an IP address and an address such as a telephone number or mail address format is performed. A gatekeeper in H.323 or a SIP server in SIP may be separately installed in the Internet 36 or the internal network 40, or may be included in the function of the NAT server group 12.

  Details of the call control server 20 configured as a communication relay device will be described below. FIG. 2 is a block diagram illustrating a schematic hardware configuration of the call control server 20 according to the present embodiment. The call control server 20 includes a central processing unit (CPU) 52, a cache memory 54 that enables high-speed access to data used by the CPU 52, and a solid-state memory device such as RAM and DRAM that enables the CPU 52 to perform processing. System memory 56 to be formed. The CPU 52, cache memory 54, and system memory 56 are connected via a system bus 58 to other devices or drivers, such as the graphics driver 60, the private NIC 24, and the global NIC 22.

  The graphics driver 60 is connected to the display 64 via the system bus 58, and can display the processing result by the CPU 52 on the display screen. The NICs 22 and 24 connect the call control server 20 to an external network at the physical layer and data link layer levels. In the present embodiment, the private NIC 24 is connected to the internal network 40 shown in FIG. 1, and the global NIC 22 is connected to the Internet 36 shown in FIG.

  An I / O bus bridge 66 is further connected to the system bus 58. On the downstream side of the I / O bus bridge 66, a hard disk device (hereinafter referred to as HDD) is referred to by IDE, ATA, ATAPI, serial ATA, SCSI, USB, etc. via an I / O bus 68 such as PCI. ) A storage device such as 70 is connected. Further, an input device 72 such as a keyboard is connected to the I / O bus 68, and receives inputs and commands from an operator such as a system administrator.

  The data communication server 30 shown in FIG. 1 can also have the same configuration as that shown in FIG. Further, the multi-function device 42, the facsimile machine 48, the T.P. The 38 gateway device 44, the IAF device 38, and the like can be configured in the same manner as shown in FIG. 2 by appropriately adding and deleting hardware and changing connections. When configured as an image communication apparatus such as the IAF apparatus 38, an image processing driver 74 and an image processing device 76 can be connected to the system bus 58. The image processing driver 74 and the image processing device 76 can be used when image processing / image output is performed by driving an image processing engine using an ADF (Automatic Document Feeder), an image scanner, and electrophotography (not shown). .

  Hereinafter, functions realized by the NAT server group 12 will be described. FIG. 3 is a functional block diagram realized on the call control server 20 and the data communication server 30. The call control server 20 shown in FIG. 3 includes a first network control unit 102 that controls packet exchange with the Internet 36 side, a second network control unit 104 that controls packet exchange with the internal network 40 side, and address translation. And a processing unit 100.

  Each network control unit 102, 104 processes a packet at the network layer and transport layer level, and determines a functional unit that passes the packet according to a port number specified in the packet. Packets in which port numbers used in call control, such as TCP / UDP Nos. 1720 and 5060, are passed to the call connection processing unit 108, while packets in which other port numbers are designated are address-translated It is passed to the processing unit 100.

  The address translation processing unit 100 refers to the address translation table 106 that registers the private IP address and port number of a node connected to the internal network 40 and the global IP address and port number in association with each other, and The address conversion process is performed by rewriting the IP address and the port number in the packet as appropriate. The packet whose address has been converted is transferred to the network control units 102 and 104 on the destination side and transmitted to the destination. In addition, packets with IP addresses and port numbers that are not registered in the address conversion table 106 are discarded.

  The call connection processing unit 108 receives the H.264 from the network control units 102 and 104. A packet for which processing according to H.323 or SIP protocol is designated is decoded, and a call connection message such as a call setting request or a response is extracted and stored in a storage area such as the system memory 56. When the call connection processing unit 108 extracts the call connection message, the call connection processing unit 108 requests the relay address determination unit 110 to determine the relay address. This relay address is an address of a server for relaying an IFP packet between the Internet-side FAX device and the internal network-side FAX device.

  In response to the request, the relay address determination unit 110 determines a relay address by referring to the server registration table 116 that registers in advance IP addresses of servers that can relay IFP packets. The relay address depends on, for example, the current number of relays of each server, whether the data channel is TCP or UDP, communication settings of each server, device information of FAX apparatuses on the Internet side and the internal network side, etc. Can be determined. Details of the relay address determination process will be described later.

  In the network environment 10 shown in FIG. 1, the servers that can be relayed include the data communication server 30-1 to the data communication server 30-N, and the call control server 20 also serves as the data communication server. Can include the call control server 20 itself. The determined relay address includes a global IP network and private IP addresses set in the two NICs of the servers 20 and 30 as a set. After the determination, the relay address determination unit 110 requests the address rewriting unit 112 to rewrite the IP address information described in the call connection message, and requests the data channel registration unit 114 to perform data channel registration processing.

  The address rewriting unit 112 rewrites the description of the information related to the data channel of the call connection message stored in the memory (hereinafter referred to as channel configuration information) to the corresponding relay address, and completes the rewriting to call connection processing. To the unit 108. Here, the corresponding relay address means a relay address in the address space of the destination network. For example, a call connection message from the Internet 36 to the internal network 40 is rewritten with the private IP address of the relay address.

  The channel configuration information to be rewritten can include the IP address and port number of the calling FAX device or the called FAX device. For example, the address rewriting unit 112 performs H.264. In the case of the H.323 first connect procedure, the IP address information set in the reverseLogicalChannelParameters in the SETUP fastStart element or the forwardLogicalChannelParameters in the CONNECT faststart element is rewritten to the relay address. Alternatively, for example, in the case of SIP, the address rewriting unit 112 rewrites the IP address information set in SDP (Session Description Parameters) to a relay address.

  After the rewriting is completed, the call connection processing unit 108 encodes the call connection message in which the address information is rewritten, and requests the address conversion processing unit 100 to perform address conversion processing and relay processing on the header portion of the packet. The address conversion processing unit 100 converts the IP address of the internal node and an appropriate port number of the IP packet header into addresses in the address space on the destination side network, and passes them to the destination side network control units 102 and 104. Then, the packet is transmitted to the destination.

  On the other hand, the data channel registration unit 114 that has received the request for registration processing notifies the device corresponding to the determined relay address of the channel configuration information at both ends of the data channel, and requests registration of relay of the IFP packet. . This registration request may be notified via either the internal network 40 or the Internet 36.

  Similar to the call control server 20, the data communication server 30 shown in FIG. 3 includes a first network control unit 122 that controls packet exchange with the Internet 36 side and a packet exchange with the internal network 40 side. 2 network control unit 124. The data communication server 30 further includes a relay processing unit 120 that relays the IFP packet and a data channel registration receiving unit 126.

  Each network control unit 122, 124 passes the received packet to the relay processing unit 120. The relay processing unit 120 refers to the data channel registration table 128 that registers the channel configuration information at both ends of the data channel that it relays in association with each other, and refers to the IP address of the header of the packet to be sent, The port number is rewritten and passed to the network control units 122 and 124 on the destination side. The packet is discarded if the IP address and port number are not registered in the data channel registration table 128.

  The data channel registration receiving unit 126 receives a data channel relay registration request from the call control server 20 and causes the relay processing unit 120 to set the requested data channel relay. The relay processing unit 120 registers the channel configuration information of the data channel in the data channel registration table 128 and opens the port. Thereafter, the registration is maintained until the disconnection of the data channel is reported, for example, when the FAX image communication is completed.

  FIG. 4 is a diagram showing a data flow of relay processing by the NAT server group 12. FIG. 4 shows a state where the Internet-side FAX device 130 and the internal network-side FAX device 140 are communicating via the call control server 20 and the data communication server 30. In the following description, it is assumed that the global IP address X is assigned to the FAX apparatus 130, the private IP address A is assigned to the FAX apparatus 140, and the FAX apparatus 130 calls the FAX apparatus 140. The data communication server 30 is assigned a global IP address Fg and a private IP address Fp, and the call control server 20 assigns the global IP address G to the FAX apparatus 140 and uses the addresses Fg and Fp as relay addresses. Shall be determined.

  T.A. In establishing 38 communication, first, a call connection message is exchanged between the FAX apparatus 130 and the FAX apparatus 140. The call control server 20 replaces the address X of the calling side device contained in the call connection message 200 transmitted from the calling side FAX device 130 with the determined relay address Fp, and receives the incoming call as the message 202 after rewriting. Relay to side FAX apparatus 140. In addition, the call control server 20 replaces the address A of the called device included in the call connection message 204 transmitted from the called FAX device 140 with the determined relay address Fg, and uses the called FAX as the message 206. Relay to device 130.

  Then, the call control server 20 corresponds to the determined relay address with the address X of the calling FAX device 130 and the address A of the called FAX device 140 together with the port number specified in the call connection message. The data communication server 30 is notified. Through the above-described call connection message relay process, each of the FAX apparatuses 130 and 140 can specify the data communication server 30 as the transmission destination of the IFP packet.

  When the data channel is established, IFP packets are exchanged between the FAX apparatuses 130 and 140 via the data communication server 30. The data communication server 30 converts the source address X into the relay address Fp for the IFP packet 208 from the Internet-side FAX device 130, while the relay address Fg that is the destination is converted to the IP address of the FAX device 140. The address is converted to address A and transmitted to the FAX apparatus 140 as an IFP packet 210.

  Further, the data communication server 30 converts the transmission source address A into the relay address Fg for the IFP packet 212 from the FAX device 140 on the internal network side, and sets the destination relay address Fp to the FAX device 130 address X. The data is converted and transmitted as an IFP packet 214 to the FAX apparatus 130. By the relay process of the IFP packet, the data channel for transmitting FAX data is exchanged between the FAX apparatuses 130 and 140 without any delay.

  Hereinafter, the relay process of the call control message will be described with reference to a flowchart. FIG. 5 is a flowchart showing the relay processing executed by the call control server 20 of this embodiment. The process shown in FIG. 5 is started from step S100 in response to the activation of the call control server 20, for example.

  In step S101, the network control units 102 and 104 that have received the packet refer to the port number specified in the packet to determine whether the incoming call is to the 5060 port corresponding to SIP. If it is determined in step S101 that the incoming call is to port 5060 (YES), the process branches to step S111. On the other hand, if it is determined in step S101 that the incoming call is not to the 5060 port (NO), the process branches to step S102.

  In step S102, the network control units 102 and 104 perform the H.264 operation. It is determined whether the incoming call is to the 1720 port corresponding to H.323. If it is determined in step S102 that the incoming call is to the 1720 port (YES), the process branches to step S103. On the other hand, if it is determined that the incoming call is not to the 1720 port (NO), The process branches to step S101 and waits until an incoming call is received at the 5060 port or 1720 port.

  In FIG. 5, the processing from step S103 to step S109 is H.264. The process corresponding to the H.323 protocol stack is shown. In step S103, the call connection processing unit 108 decodes the received packet. It is determined whether the call connection message conforms to H.323. In step S103, H.D. If it is determined that the message is not the H.323 message (NO), the process branches to step S117. In step S117, the packet is discarded, and the process passes again to step S101 via point A, and waits for an incoming call for the next 5060 port or 1720 port.

  On the other hand, in step S103, the received packet is H.264. If it is determined that the call connection message conforms to H.323 (YES), the process branches to step S104. In step S104, the call connection processing unit 108 determines whether or not a faststart element is included in the call connection message. If the faststart element is not included in step S104 (NO), the process branches to step S110 via point B. In step S110, the packet is transmitted as it is, and the processing is looped until the next 5060 port or 1720 port is received.

  On the other hand, if a faststart element is included in step S104 (YES), the process branches to step S105. In step S105, the call connection processing unit 108 determines whether the call connection message is from the calling side corresponding to SETUP or from the called side corresponding to CONNECT.

  If it is determined in step S105 that the caller is the calling party (YES), the process branches to step S106, the relay address determination process is called, and the relay address is acquired. In step S107, the IP address set in the reverseLogicalChannelParameters of the SETUP is rewritten with the determined corresponding relay address. More specifically, if it is an incoming call from the Internet side, it is rewritten to a private IP address, whereas if it is an incoming call from the internal network side, it is rewritten to a global IP address.

  In step S109, the server corresponding to the determined relay address is notified of the channel configuration information on the calling side to request registration of the data channel. In step S110, the rewritten call connection message is encoded, the packet is transmitted to the destination, the process returns to step S101, and the process is looped until the next 5060 port or 1720 port is received.

  On the other hand, if it is determined in step S105 that the call is on the called side (NO), the process branches to step S108. In step S108, the IP address set in forwardLogicalChannelParameters is rewritten with the corresponding relay address determined by the call connection message on the calling side. In step S109, the server corresponding to the relay address is notified of the channel configuration information on the called side and requests registration of the data channel. In step S110, the rewritten call connection message is encoded, the packet is transmitted, and the process returns to step S101.

  The processing from step S111 to step S116 shows processing in the case of the SIP protocol. In step S111, the call connection processing unit 108 determines whether or not the received packet is a call connection message according to SIP. If it is determined in step S103 that the message is not a SIP message (NO), the process branches to step S117, the packet is discarded, and the process returns to step S101 again via point A.

  On the other hand, if it is determined in step S111 that the received packet is a call connection message according to SIP (YES), the process branches to step S112. In step S112, the call connection processing unit 108 determines whether or not SDP is included in the call connection message. If SDP is not included in step S112 (NO), the process branches to step S110 via point B. In step S110, the packet is transmitted as it is, and the processing is looped until the next 5060 port or 1720 port is received.

  On the other hand, if SDP is included in step S112 (YES), the process branches to step S113. In step S113, the call connection processing unit 108 determines whether the call connection message is INVITE and is from the calling side, or is a response to INVITE such as 200OK and is from the called side. .

  If it is determined in step S113 that the caller is the calling party (YES), the process branches to step S114, the relay address determination process is called, and the relay address is acquired. In step S115, the IP address set in the SDP of the SIP message is rewritten with the determined corresponding relay address. In step S116, the caller side channel configuration information is notified to the server corresponding to the determined relay address, and the registration of the data channel is requested. In step S110, the rewritten call connection message packet is transmitted to the destination, the process returns to step S101, and the process is looped until the next 5060 port or 1720 port is received.

  On the other hand, if it is determined in step S113 that the call is on the called side (NO), the process branches to step S115. In step S115, the IP address set in the SDP of the SIP message is rewritten with the corresponding relay address determined by the call connection message on the calling side. In step S116, the server 30 corresponding to the relay address is notified of the channel configuration information on the called side to request registration of the data channel. In step S110, the rewritten call connection message packet is transmitted, and the process returns to step S101.

  Hereinafter, the relay address determination process called in steps S106 and S114 shown in FIG. 5 will be described. FIG. 6 is a flowchart showing a relay address determination process executed by the relay address determination unit 110. The process shown in FIG. 6 is called in steps S106 and S114 shown in FIG. 5, and is started from step S200. In step S201, the server registration table 116 is referred to and it is determined whether or not the data communication server 30 is registered.

  Here, the server registration table referred to in step S201 will be described with reference to FIG. FIG. 8 shows an embodiment of the data structure of the server registration table 116. The server registration table 116 shown in the figure includes a field 116a in which the server identification value of the registered data communication server 30 is input, a field 116b in which the global IP address of the data communication server 30 is registered, and a private IP. And a field 116c in which an address is registered.

  Further, the server registration table 116 includes a field 116d in which an upper limit value of the number of relays permitted to be relayed to the server, a field 116e in which a group divided according to the load is input, and the current number of relays of the server. Field 116f for registering the number of relays of each server. The server registration table 116 is registered in advance through a user interface by an administrator or the like, and updated by data channel registration or the like.

  Refer to FIG. 6 again. If it is determined in step S201 that the data communication server 30 is not registered (NO), the process branches to step S202. In step S202, a set of the relay global IP address and private address of the call control server 20 itself is determined as a relay address, the process is terminated in step S206, and the original process shown in FIG. 5 is controlled. hand over.

  On the other hand, if it is determined in step S201 that there is at least one registration of the data communication server 36, the process branches to step S203. In step S203, it is determined whether or not there is only one registration of the data communication server 30. If it is determined in step S203 that there is only one registration (YES), the process branches to step S204. In step S204, the set of only one registered global IP address and private address of the data communication server 30 is determined as a relay address, and in step S206, the process is terminated, and the original process shown in FIG. Pass control to.

  On the other hand, if it is determined in step S203 that there are a plurality of registrations (NO), the process branches to step S205. In step S205, the search process for the most optimal relay address is called, the server with the smallest number of relays is searched within the search range, and the set of the searched global IP address and private IP address is determined as the relay address. In step S206, the process is terminated, and control is passed to the original process shown in FIG.

  Hereinafter, the search process called in step S205 shown in FIG. 6 will be described. FIG. 7 is a flowchart showing search processing executed by the relay address determination unit 110. The process shown in FIG. 7 is called in step S205 shown in FIG. 6, and is started from step S300. In step S301, the field 116d and the field 116f of the server registration table 116 are compared to determine whether or not there is at least one data communication server whose current number of relays is equal to or less than the upper limit value.

  If it is determined in step S301 that there is no data communication server with the current number of relays equal to or less than the upper limit, the process branches to step S310. In step S310, the call control server 20 itself is set for the data channel, and the value of the number of relays of the own device is added. In step S306, the relay global IP address and private address set is determined as the relay address, the search process is terminated in step S307, and the process returns to the process shown in FIG.

  On the other hand, if it is determined in step S301 that there is at least one data communication server with the number of relays equal to or less than the upper limit (YES), the process branches to step S302. In step S302, either one of the calling side and the called side is set to T.P. It is determined whether or not 38 gateway devices are included. This determination is made, for example, by acquiring the identification information of the called side and the calling side FAX device included in the message when exchanging the call connection message and registering the identification information of the gateway device or the IFA device in advance. It can be implemented by reference.

  In step S302, T. If it is determined that 38 gateway devices are included (YES), the process branches to step S309. In step S309, the field 116e of the server registration table 116 is referred to, and the server entry grouped with the load “low” is set in the search range. In step S305, the search range set in the server registration table 116 is set. The server for data communication with the smallest number of relays is searched, the searched server is set for the data channel, and the value of the number of relays of the server is added. In step S306, the set of the global IP address and private address of the server is determined as a relay address, the search process is terminated in step S307, and the process returns to the process shown in FIG.

  On the other hand, in step S302, T. If it is determined that 38 gateway devices are not included (NO), the process branches to step S303. In step S303, it is determined whether the transport layer of the data channel is established by UDP. If it is determined in step S303 that it is UDP (YES), the process branches to step S308.

  In step S308, referring to the field 116e of the server registration table 116, the server entry grouped with the load “medium” is set in the search range, and in step S305, the current number of relays in the set search range. The data communication server 30 having the smallest number is searched, the searched server is set for the data channel, and the number of relays of the server is added. In step S306, the set of the global IP address and private address of the server is determined as a relay address, the search process is terminated in step S307, and the process returns to the process shown in FIG.

  On the other hand, if it is determined in step S303 that TCP is not UDP (NO), the process branches to step S304. In step S304, referring to the field 116e of the server registration table 116, the server entry grouped with the load “high” is set in the search range, and in step S305, the current number of relays in the set search range. The data communication server 30 having the smallest number is searched and set for the data channel, and the value of the number of relays is added. In step S306, the set of addresses of the server is determined as a relay address, the search process is terminated in step S307, and the process returns to the process shown in FIG.

  Hereinafter, processing on the data communication server side that receives a notification from the call control server 20 will be described. FIG. 9 is a diagram illustrating an embodiment of a data channel registration process executed by the data communication server 30. The process shown in FIG. 9 is started from step S400 in response to the activation of the data communication server 30, for example. In step S401, the data channel registration receiving unit 126 waits for a data channel registration request, and loops the process in step S401 until the registration request is received.

  On the other hand, if it is determined in step S401 that a data channel registration request has been made, the process branches to step S402. In step S402, the data channel registration receiving unit 126 sets the IP channel and the port number to the data channel so as to permit the relay processing unit 120 to relay the data channel requested for registration according to the notified channel configuration information. Register in the registration table 128 and loop the process again to step S401.

  5, 6, 7, and 9 described above, the address information included in the call connection message is rewritten to the corresponding address of the data communication server 30 that relays the data channel. . As a result, the FAX data via the relay address server between the FAX device 130 on the Internet side in the global IP address space and the FAX device 140 on the internal network side in the private IP address space regardless of the address space difference. Data channels can be established. Even if the address spaces of the addresses assigned to the FAX apparatuses 130 and 140 at both ends are different, the data channel can be established. On the other hand, since a packet not registered is discarded, facsimile communication with high security is possible.

  Further, in the above embodiment, depending on the number of relays currently maintained by each server, the devices at both ends are either gateway devices or IAF devices, and the communication channel is configured by either a UDP port or a TCP port. The relay address is determined in consideration of whether it is set. Therefore, a server having a relatively small load is automatically selected during call control, and highly stable facsimile communication is possible. In addition, it is a communication and connectionless protocol that includes a gateway device that is prone to packet delay and loss, and has a relatively low load in advance for communication that uses UDP that is likely to cause packet delay and loss as a transport layer protocol. It becomes possible to determine the relay address from the group set so as to enable more stable facsimile communication according to the characteristics of individual communication.

  In the above description, the processing for registering the data channel has been mainly described. However, when the facsimile image communication is completed and the data channel is closed, it is needless to say that the registration of the unnecessary channel can be appropriately deleted from the data channel registration table.

  As described above, according to the embodiment of the present invention, it is possible to establish a communication channel used for facsimile data transmission of facsimile communication between communication devices connected to networks in different address spaces. A communication relay device, a communication system, a communication method, and a program can be provided.

  The above function can be realized by a device executable program described in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark), an object-oriented programming language, or the like. ROM, EEPROM, EPROM, It can be stored in a device-readable recording medium such as flash memory, flexible disk, CD-ROM, CD-RW, DVD, SD memory, MO, and distributed.

  The communication relay device can be configured as any network communication device such as a personal computer, a workstation, a blade server, an appliance server, a mainframe, or any other computer device, a router, or a gateway.

  Although specific embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and those skilled in the art will conceive other embodiments, additions, modifications, deletions, and the like. It can be changed within the range that can be achieved, and any aspect is included in the scope of the present invention as long as the effects and effects of the present invention are exhibited.

1 is a schematic diagram illustrating an embodiment of a network environment. The block diagram which shows the schematic hardware constitutions of the server for call control of this embodiment. The functional block diagram implement | achieved on the server for call control, and the server for data communication. FIG. 4 is a data flow diagram of relay processing by a NAT server group. The flowchart which shows the relay process which the server for call control of this embodiment performs. The flowchart which shows the determination process of the relay address which a relay address determination part performs. The flowchart which shows the search process which a relay address determination part performs. The figure which shows embodiment of the data structure of a server registration table. The flowchart which shows embodiment of the data channel registration process which the server for data communication performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Network environment, 12 ... NAT server group, 20 ... Call control server, 22, 24 ... NIC, 30 ... Data communication server, 32, 34 ... NIC, 36 ... Internet, 38 ... IAF apparatus, 40 ... Internal network , 42 ... MFP, 44 ... gateway device, 46 ... telephone network, 48 ... G3 FAX device, 52 ... CPU, 54 ... cache memory, 56 ... system memory, 58 ... system bus, 60 ... graphics driver, 64 ... Display, 66 ... I / O bus bridge, 68 ... I / O bus, 70 ... HDD, 72 ... Input device, 74 ... Image processing driver, 76 ... Image processing device, 100 ... Address conversion processing unit, 102 ... First network control unit 104 ... Second network control unit 106 ... Address conversion table 108 ... Call Subsequent processing unit 110 ... relay address determination unit 112 112 address rewriting unit 114 data channel registration unit 116 server registration table 120 data relay processing unit 122 first network control unit 124 second network Control unit 126... Data channel registration acceptance unit 128 128 data channel registration table 130 130 140 FAX device 200 202 202 204 206 message 208 210 210 212 214 IFP packet

Claims (12)

A communication relay device connected to both the first network in the first address space to which the first communication device is connected and the second network in the second address space to which the second communication device is connected,
Processing means for relaying messages exchanged between the communication devices in accordance with a call control protocol for facsimile communication;
Determining means for determining a relay address used for relaying between the networks for a communication channel used for transmitting facsimile data of the facsimile communication;
Rewriting means for rewriting the address of the communication channel included in the message received from each of the communication devices to the relay address on a corresponding address space;
Registration means for registering permission for relaying the facsimile data via the communication channel.   The determining means determines the relay address with reference to a table for registering addresses of at least one data communication relay device connected to both the networks, and the registering means determines the determined relay address. 2. The communication relay device according to claim 1, wherein information corresponding to the communication channel is notified to a corresponding communication relay device, and permission for relaying the facsimile data is registered.   The communication relay device according to claim 1, wherein the determination unit determines the relay address according to the number of relays maintained by each communication relay device.   The communication relay device according to claim 1, wherein the determining unit determines the relay address according to whether the communication device is a gateway device or a direct-coupled facsimile device.   The communication relay device according to claim 1, wherein the determination unit determines the relay address according to whether the communication channel is configured by a UDP port or a TCP port.   The rewriting means sets the address on the first communication device side of the communication channel described in the message relayed from the first communication device to the second communication device as the relay address in the second address space. Rewriting, rewriting the address on the second communication device side of the communication channel described in the message relayed from the second communication device to the first communication device to the relay address in the first address space. Item 6. The communication relay device according to any one of Items 1 to 5.   The first address space or the second address space is a private IP address space or a global IP address space, and the communication channel includes an IP address and a port number. The communication relay device according to 1. The communication relay device according to any one of claims 1 to 7,
One or more data communication relay devices connected to both of the networks and relaying data transmission of communication channels. A communication method executed by a communication relay device connected to both a first network in a first address space to which a first communication device is connected and a second network in a second address space to which a second communication device is connected. ,
Receiving a message exchanged between the communication devices in accordance with a facsimile communication call control protocol;
Determining a relay address used for relaying between the networks for a communication channel used for transmitting facsimile data of the facsimile communication;
Rewriting the address of the communication channel included in the message received from each communication device to the relay address on the corresponding address space;
Sending the rewritten message; and
Registering permission to relay the facsimile data via the communication channel. The step of determining includes a sub-step of referring to a table for registering an address of at least one data communication relay device connected to both of the networks;
The communication method according to claim 9, wherein the registering step includes a sub-step of notifying information constituting the communication channel to a communication relay device corresponding to the determined relay address.   In the rewriting step, when the message is directed from the first communication device to the second communication device, the address on the first communication device side of the communication channel described in the message is changed to the first communication device. If the message is directed from the second communication device to the first communication device, the second communication device side of the communication channel described in the message is rewritten to the relay address in a two-address space. The communication method according to claim 9 or 11, wherein the address is rewritten to the relay address in the first address space.   An apparatus-executable program for causing a communication relay apparatus to function as each unit according to any one of claims 1 to 7.

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