JP4642649B2 - Relay device - Google Patents

Description

  The present invention relates to a relay device for relaying data exchanged between a plurality of networks.

  As is well known, organizations such as government offices have constructed and operated a system for remotely monitoring a route to be monitored such as a river or a road. In this type of system, stream content data generated by a plurality of monitoring cameras installed at each point on the monitoring target path can be received by a host on the private network. For this reason, the supervisor can remotely monitor the monitoring target route centrally through several stream contents reproduced on the host.

  In the field of the remote monitoring system described above, a private multicast network is often used as a communication network for stream content data. A multicast network distinguishes each video resource (stream content) in units of groups, and for each router that configures the network, to which router multicast packets from the source (encoder connected to the surveillance camera) are sent. When the participation of a group from a listener (host) on the network is declared to a router or source, video of the group along the defined route from the source to that listener is declared. It is to deliver resources.

  Recently, there is a demand from organizations operating a stream distribution service in such a private multicast network to provide each other's video resources. In order to provide each other's video resources, private networks must be connected by some means, but since multicast networks are operated by a single address system, private networks are simply connected. There was a situation that could not be done.

  Under such circumstances, the present applicant has previously proposed a relay device for connecting private multicast networks (see Patent Document 1). When this relay device relays a multicast packet between multicast networks, a multicast group address described in the packet and a private IP [Internet Protocol] address of the source are virtualized from the source to the source. The process of rewriting to what is set automatically is performed. This relay device internally holds a table defining address correspondences for such rewrite processing.

JP 2005-244904 A

  In the multicast network described above, all multicast group addresses are managed in a server or a router. Therefore, if video resources are mutually used by the technique previously proposed by the present applicant, both groups' multicast networks must manage all of the multicast group addresses of both groups. That is, in one multicast network, all of its own multicast group addresses and all of the multicast group addresses in the other multicast network must be managed together.

  However, in the multicast networks of these organizations, when the size of the video resources is too large, for example, when the number of video resources of one organization is 5000 and the number of video resources of the other organization is 50, In a multicast network with a smaller number of video resources, the number of multicast group addresses to be managed becomes enormous, and the amount of stream content data (multicast packets) flowing through the network also becomes enormous. You need to switch to something. As a result, especially in a small-scale multicast network, the introduction cost for mutual use of video resources increases, so organizations using small-scale multicast networks had to reduce mutual use of video resources. .

  The present invention has been made in view of the problems of the prior art as described above, and the problem is that a heavy load is applied to two private multicast networks having different video resource scales. It is to make it possible to mutually use video resources between these multicast networks without improving the performance of the network.

A relay device devised to solve the above problem is a relay device for connecting first and second multicast networks configured by several PIM-compatible routers so as to be capable of multicast communication. A plurality of network interfaces respectively connected to the routers of the first and second multicast networks, and a multicast group respectively assigned to the stream contents so that a listener receives the stream contents from the source in the second multicast network The listener of the first multicast network receives the stream contents to which the multicast group address is assigned for each of several multicast group addresses. A first storage unit for storing a first virtual group address in association with the first virtual group address, and the network interface receives a multicast packet addressed to the first virtual group address from a router of the first multicast network When received, the first storage unit reads the multicast group address corresponding to the first virtual group address, and rewrites the first virtual group address in the multicast packet with the read multicast group address. An address conversion unit, a first transmission unit configured to transmit a multicast packet whose address has been rewritten by the first address conversion unit to the router of the second multicast network through the network interface; When the network interface receives the multicast packet from the router of the second multicast network as a response from the source in the second multicast network to which the multicast packet is transmitted from the transmission unit, from the first storage unit, Read the first virtual group address corresponding to the multicast group address described in the multicast packet, and rewrite the multicast group address in the multicast packet with the read first virtual group address. A multicast packet whose address has been rewritten by the translation unit and the first address reverse translation unit is routed through the network interface to the route of the first multicast network. When the second transmission unit that transmits data to the network and the network interface receives a request from any listener in the first multicast network, the first storage unit associates the request with the virtual group address. A first list generation unit that generates list information for displaying a list of stream contents assigned to a multicast group address, and when the first list generation unit generates the list information, the generated list information is The first list information transmission unit that transmits to the listener that has transmitted the request in the first multicast network through the network interface, and the network interface receives an instruction to change the list contents from the listener. If, luma put a multicast group address associated with the first virtual group address in the first storage portion, another not associated with the first virtual group address, the second multicast network It is characterized by comprising a first dynamic address changing unit that changes to a multicast group address and causes the first list generating unit to generate list information.

  In this way, for the first multicast network, a virtual group address smaller than the number of multicast group addresses set in the second multicast network is set, and multicast between one multicast network and the other multicast network is set. If the packet is relayed and the multicast group address assigned to the virtual group address is changed to another multicast group address when a request is received from the listener, the first multicast All the video resources of the second multicast network can be used while limiting the number of virtual group addresses used in the network to such an extent that congestion does not occur.

  Therefore, according to the present invention, video resources can be mutually exchanged between these multicast networks without imposing a heavy load on the two private multicast networks having a difference in the size of the video resources or improving the performance. It becomes available.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram of a computer network system according to the present embodiment.

  The computer network system according to the present embodiment includes a private multicast network A, a private multicast network B, and the relay device 10.

  The private multicast network A is a network formed by communicatively connecting a plurality of computers, and an address system independent of an external network is set for each computer. Specifically, the multicast network A according to the present embodiment includes two encoders (ENC_A1, ENC_A2), three layer 3 switches (RP_A1, RP_A2, BSE_A), and one layer 2 switch (L2SW_A2).

  Each of the two encoders (ENC_A1, ENC_A2) is a device that converts a video signal output from the surveillance camera into stream content data and outputs it to the network, and is connected to the surveillance cameras 21 and 22, respectively. .

  Each of the three layer 3 switches (RP_A1, RP_A2, and BSR_A) is a communication computer that relays an IP [Internet Protocol] packet according to a TCP / IP [Transmission Control Protocol / Internet Protocol] protocol suite. These three layer 3 switches (RP_A1, RP_A2, and BSR_A) are communication computers that also relay multicast packets according to the PIM-SM (Protocol Independent Multicast-Sparse Mode) module that constitutes the TCP / IP suite. ing. Of the three layer 3 switches (RP_A1, RP_A2, and BSR_A), one layer 3 switch (BSR_A) determines the rendezvous point (RP) from among the PIM-compatible routers in the network A. It has a function as a router. The remaining two routers (RP_A1, RP_A2) are layer 3 switches determined as rendezvous points by the bootstrap router (BSR_A), and both are connected to the bootstrap router (BSR_A).

  One layer 2 switch (L2SW_A2) is a communication device that relays frames according to the Ethernet [Ethernet: Trademark of Xerox Corporation, Intel Corporation, Compaq Computer Corporation] standard. This layer 2 switch (L2SW_A2) connects each encoder (ENC_A1, ENC_A2) and rendezvous point router (RP_A2).

  Further, in this multicast network A, the receiving terminal devices 23 and 24 for decoding the stream content data and receiving the stream content by receiving the multicast packet are respectively a rendezvous point router (RP_A1) and a rendezvous point router ( RP_A2).

  For the sake of explanation, private IP addresses 10.0.1.1 and 10.0.1.2 are set for the two encoders (ENC_A1 and ENC_A2), respectively, and the two rendezvous point routers (RP_A1 and RP_A2) are The private IP addresses 10.0.0.1 and 10.0.0.2 are set, the private IP address 10.0.0.3 is set in the bootstrap router (BSR_A), and 10.1.1.1, Assume that a private IP address of 10.1.2.1 is set.

  In addition, it is assumed that multicast group addresses 230.1.1.1 and 230.1.1.2 are set for stream contents (video resources) distributed by multicast from the two encoders (ENC_A1 and ENC_A2), respectively.

  On the other hand, the private multicast network B is also a network in which a plurality of computers are communicably connected, and an address system independent of an external network is set for each computer. Specifically, the multicast network B of this embodiment includes six encoders (ENC_B1 to ENC_B6), four layer 3 switches (RP_B1 to RP_B3, BSE_B), and three layer 2 switches (L2SW_B1 to L2SW_B3). Become.

  Each of the six encoders (ENC_B1 to ENC_B6) is a device that converts a video signal output from the surveillance camera into stream content data and outputs it to the network, and is connected to the surveillance cameras 31 to 36, respectively. .

  Each of the four layer 3 switches (RP_B1 to RP_B3, BSR_B) is a communication computer that relays IP packets according to the TCP / IP protocol suite. The four layer 3 switches (RP_B1 to RP_B3, BSR_B) are communication computers that also relay multicast packets in accordance with the PIM-SM modules that constitute the TCP / IP suite. Of the four layer 3 switches, one layer 3 switch (BSR_B) is a bootstrap router, and the remaining three routers (RP_B1 to RP_B3) are rendezvous point routers. . The rendezvous point routers (RP_B1 to RP_B3) are connected to each other, and the bootstrap router (BSR_B) is connected to the rendezvous point router (RP_B2).

  The three layer 2 switches (L2SW_B1 to L2SW_B3) are all communication devices that relay frames according to the Ethernet standard. Among these, the layer 2 switch (L2SW_B1) connects the encoder (ENC_B1, ENC_B2) and the rendezvous point router (RP_B1), and the layer 2 switch (L2SW_B2), the encoder (ENC_B3, ENC_B4) and the rendezvous point router (RP_B2). The layer 2 switch (L2SW_B3) connects the encoder (ENC_B5, ENC_B6) and the rendezvous point router (RP_B3).

  Further, in this multicast network B, the receiving terminal device 37 is connected to the bootstrap router (BSR_B).

  Here, for the sake of explanation, private IP addresses of 10.2.1.1, 10.2.2.1, 10.3.1.1, 10.3.2.1, 10.4.1.1, and 10.4.2.1 are set for the six encoders (ENC_B1 to ENC_B6), respectively. The three rendezvous point routers (RP_B1 to RP_B3) have 10.0.0.4, 10.0.0.5 and 10.0.0.6 private IP addresses, respectively, and the bootstrap router (BSR_B) has 10.0.0.7 private IP addresses. It is assumed that an IP address is set and the receiving terminal device 37 is set with a private IP address of 10.5.1.1.

  In addition, it is assumed that multicast group addresses of 230.1.1.1 to 230.1.1.6 are set for stream contents (video resources) distributed by multicast from the six encoders (ENC_B1 to ENC_B6), respectively.

  FIG. 2 is a configuration diagram of the relay apparatus 10.

  The relay apparatus 10 is a communication computer that relays multicast packets exchanged between apparatuses on the multicast network A and apparatuses on the multicast network B according to PIM-SM between the networks A and B.

  The relay device 10 includes a multicast interface (IF) 10a for A, a multicast interface (IF) 10b for B, a CPU [Central Processing Unit] 10c, a DRAM [Dynamic Random Access Memory] 10d, and a storage 10e. Yes.

  Among them, the A IF 10a is connected to the bootstrap router (BSR_A) of the multicast network A, and the B IF 10b is connected to the bootstrap router (BSR_B) of the multicast network B. For the sake of explanation, it is assumed that a private IP address 10.0.1.1 is set in the IF IF 10a and a private IP address 10.0.1.2 is set in the IF IF 10b.

  Further, the storage 10e stores several programs that are expanded in the DRAM 10d by the CPU 10c. The program stored in the storage 10e includes a TCP / IP protocol suite 11 and a content list providing application 12.

  The TCP / IP protocol suite 11 is a program group for realizing the IP packet relay function on a computer. The TCP / IP protocol suite 11 includes a PIM-SM module (program) 11a, and the PIM-SM module 11a includes an address setting program and an address conversion program described later. .

  On the other hand, the content list providing application 12 is software for realizing functions described later on a computer. The content list providing application 12 includes an HTTP [HyperText Transfer Protocol] server module (program). This HTTP server module is software for transmitting a web page at a specified URL [Uniform Resource Locator] to the HTTP client when a request is received from the HTTP client.

  Further, the storage 10e stores table groups 13a to 15a and 13b to 15b used by the program group in the PIM-SM module 11a for processing.

  FIG. 3 is a diagram illustrating an example of a data structure of the A RP information management table 13a.

  The A RP information management table 13a is a table for managing the RP information that the relay apparatus 10 should have as a rendezvous point of the multicast network A. When the A RP information management table 13a is selected as a rendezvous point from the A side bootstrap router (BSR_A). Is created based on information (bootstrap message) notified to the user.

  The A-use RP information management table 13a has the same number of records as the multicast group address set in the multicast network A. Each record has fields of “multicast group address” and “RP”. The “multicast group address” field is a field in which the multicast group address is recorded, and the “RP” field is the private IP address of the rendezvous point router closest to the video content distribution source to which the multicast group address is assigned. The field to be recorded.

  FIG. 4 is a diagram illustrating an example of the data structure of the B RP information management table 13b.

  The B RP information management table 13b is a table for managing RP information that the relay apparatus 10 should have as a rendezvous point of the multicast network B. When the B RP information management table 13b is selected as a rendezvous point from the B-side bootstrap router (BSR_B). Is created based on information (bootstrap message) notified to the user.

  The B-use RP information management table 13b has the same number of records as the multicast group address set in the multicast network B. Each record has fields of “multicast group address” and “RP”, and the meaning of these fields is the same as that of the A-use RP information management table 13a of FIG.

  FIG. 5 is a diagram illustrating an example of a data structure of the content information management table for A 14a.

  The content information management table 14a for A is a table for managing content information used when providing a list of video contents to the receiving terminal devices 23 and 24 in the multicast network A.

  The content information management table 14a for A has the same number of records as the multicast group address set in the multicast network A, and is set for some of the video contents in the multicast network B. It has the same number of records as the virtual group address. Each record has fields of “multicast group address” and “title”. The “multicast group address” field is a field in which a multicast group address or a virtual group address is recorded. The “title” field is a field in which the title of the video content in which the multicast group address is set is recorded. As will be described later, since the video content of the multicast network B is dynamically assigned to the virtual group address for the receiving terminal devices 23 and 24 of the multicast network A, a corresponding title is not determined. Accordingly, in the record of the virtual group address, the “title” field is blank.

  FIG. 6 is a diagram illustrating an example of a data structure of the content information management table for B 14b.

  The content information management table for B 14b is a table for managing content information used when providing a list of video content to the receiving terminal device 37 in the multicast network B.

  The content information management table for B 14b has the same number of records as the multicast group address set in the multicast network B, and further, virtual group addresses set for all video contents in the multicast network A Have the same number of records. Each record has fields of “multicast group address” and “title”. The “multicast group address” field is a field in which a multicast group address or a virtual group address is recorded. The “title” field is a field in which the title of the video content in which the multicast group address is set is recorded. Since the video content of the multicast network B assigned to the virtual group address for the receiving terminal device 37 of the multicast network B is fixed, the corresponding title is determined. Therefore, also in the record of the virtual group address, the title of the corresponding video content is recorded in the “title” field.

  FIG. 7 is a diagram illustrating an example of the data structure of the multicast group address translation definition table 15a for A.

  The multicast group address conversion definition table 15a for A converts the multicast group address described in the multicast packet to that of the multicast network B when the multicast packet destined for the virtual group address arrives from the multicast network A. It is a table for managing address correspondence information used at the time.

  The multicast group address conversion definition table 15a for A has the same number of records as the virtual group addresses for the receiving terminal devices 23 and 24 of the multicast network A. Each record has fields of “A”, “B”, and “fixed”. The “A” field is a field in which a virtual group address is recorded, and the “B” field is a field in which a multicast group address of the multicast network B associated with the virtual group address is recorded. The “fixed” field is a field in which flag information indicating whether multicast packets are distributed from any source (encoder (ENC_B1 to ENC_B6)) of the multicast network B using the virtual group address is recorded. When a multicast packet is distributed from the source on the B side using the virtual group address, information indicating that (“◯” in FIG. 7) is recorded in the “fixed” field.

  The multicast group address translation definition table 15a for A corresponds to the first storage unit described above.

  FIG. 8 is a diagram illustrating an example of a data structure of the multicast group address translation definition table 15b for B.

  The multicast group address conversion definition table 15b for B converts the multicast group address described in the multicast packet into that of the multicast network A when the multicast packet destined for the virtual group address arrives from the multicast network B. It is a table for managing address correspondence information used at the time.

  The multicast group address conversion definition table 15b for B has the same number of records as the virtual group address for the receiving terminal device 37 of the multicast network B. Each record has fields “A” and “B”. The “A” field is a field in which a multicast group address of the multicast network A is recorded, and the “B” field is a field in which a virtual group address associated with the multicast group address is recorded.

  The multicast group address translation definition table 15a for A corresponds to the second storage unit.

  FIG. 9 is a diagram illustrating a flow of processing performed in the system when the relay apparatus 10 is selected as a rendezvous point from the B-side bootstrap router (BSR_B).

  First, the bootstrap router (BSR_B) periodically sends a bootstrap message to all PIM-compatible routers that are candidates for rendezvous points as a function according to the PIM-SM (steps). S101). In the bootstrap message, multicast group addresses are listed, and private IP addresses of rendezvous point candidate routers corresponding to each multicast group address are listed.

  When such a bootstrap message is sent from the bootstrap router (BSR_B) to the relay device 10, the CPU 10c of the relay device 10 executes the address setting program included in the PIM-SM module 11a using the reception as a trigger. . Then, the CPU 10c performs a process of generating a candidate RP advertisement message based on the content of the received bootstrap message (step S201), and then the generated candidate RP advertisement message is sent to a router other than the router that sent the bootstrap message. Is transmitted to all the PIM compatible routers (that is, the PIM compatible router on the A side) (step S202).

  At this time, if the candidate RP advertisement message is generated in a normal rendezvous point router, the multicast group address included in the bootstrap message is listed in the candidate RP advertisement message. In the form, the candidate RP advertisement message generated by the relay device 10 is a list in which only virtual group addresses are listed. Further, in this candidate RP advertisement message, the private IP address of the A IF 10a of the relay apparatus 10 is described as an IP address to be advertised to the A-side PIM compatible router as a rendezvous point candidate.

  Then, after transmitting the candidate RP advertisement message, the CPU 10c generates the B RP information management table 13b of FIG. 4 based on the content described in the received bootstrap message, and stores it in the storage 10e. (Step S203). Thereafter, the CPU 10c ends the process according to FIG.

  By performing such processing, the relay device 10 holds the B RP information management table 13b, and the relay device 10 functions as a rendezvous point of the multicast network B.

  Although not shown, a bootstrap message is periodically sent from the bootstrap router (BSR_A) of the multicast network A to the relay device 10. In this case, as shown in FIG. 9, the CPU 10c lists the virtual group addresses (the lower two addresses in FIG. 6) without using the contents of the received bootstrap message. A candidate RP advertisement message in which the private IP address of the IF 10b is described is generated and transmitted to the B-side bootstrap router (BSR_B). Thereafter, based on the contents described in the bootstrap message, FIG. RP information management table 13a for A is generated and stored in the storage 10e. Through such processing, the relay device 10 functions as a rendezvous point of the multicast network A.

  FIG. 10 is a diagram illustrating a flow of processing performed in the system when the receiving terminal devices 23 and 24 of the multicast network A acquire video content.

  In the receiving terminal devices 23 and 24 of the multicast network A, when the web browser is activated and a URL including the domain of the relay device 10 and the activation command of the content list providing application 12 is input, the web browser transmits a request message. Processing to transmit is performed (step S301), and the system waits until a response message returns.

  On the other hand, in the relay device 10, when a request message is sent from the web browser of the receiving terminal device 23 (or 24) of the multicast network A, the content list providing application 12 is activated, and the CPU 10c receives the request message. Is performed (step S401).

  Then, the CPU 10c performs processing for generating web page data based on the content information management tables 14a and 14b and the multicast group address conversion definition table 15a (step S402). Specifically, the CPU 10c first reads the title corresponding to the multicast group address in the content information management table 14a for A in FIG. Subsequently, the CPU 10c reads the multicast group address of the multicast network B corresponding to the virtual group address in the table 14a from the multicast group address conversion definition table 15a for A in FIG. 7 and reads the title corresponding to the read multicast group address. , Read out from the content information management table 14b for B in FIG. Then, the CPU 10c generates web page data for displaying the web page in which the read titles are listed.

  The CPU 10c executing step S402 corresponds to the first list generation unit described above.

  After generating the web page data, the CPU 10c generates a response message including the data in the body, and transmits the response message to the web browser of the requesting receiving terminal device 23 (or 24) (step S403), and the request message is transmitted again. It waits until it times out or times out (step S404; NO, S405; NO).

  The CPU 10c executing step S403 corresponds to the first list information transmission unit described above.

  On the other hand, the web browser of the requesting receiving terminal device 23 (or 24) in the multicast network A performs the process of receiving the response message (step S302), and then performs the process of displaying the web page on the display device. (Step S303).

  FIG. 11 is a diagram illustrating an example of a web page 41 in which a title list of video content is described.

  As shown in FIG. 11, the web page 41 includes a clickable button 41a in which title names are respectively described. The web page 41 includes a next list button 41b clicked by a user who wants to obtain the next title list and an end button 41c clicked by the user who wants to finish obtaining the content list. It is shown.

  Then, after displaying the web page 41 as shown in FIG. 11 on the display device, the web browser of the receiving terminal device 23 (or 24) waits until any of the buttons 41a to 41c in the page 41 is clicked. To do.

  When the next list button 41b is clicked among the buttons 41a to 41c (step S304; YES), the web browser of the receiving terminal device 23 (or 24) displays the command information incorporated in the next list button 41b. Is sent to the relay device 10 (step S305), and the system waits until a response message is sent.

  On the other hand, when the CPU 10c of the relay device 10 receives the response message (step S404; YES) before the timeout occurs (step S405; NO), the multicast group address conversion definition table 15a for A in FIG. It is determined whether or not the information indicating the distribution (“◯” in FIG. 7) is recorded in the “fixed” field of all records (step S406).

  If the information indicating that the distribution is in progress is not recorded in the “fixed” field of all the records (step S406; YES), the CPU 10c determines that the distribution in the multicast group address conversion definition table 15a for A in FIG. For the records whose information is not recorded in the “fixed” field, the multicast group address in the “B” field of those records is rewritten to another one not associated with the virtual group address (step S407). In the example of FIG. 7, when the multicast group address 230.1.1.1 of the multicast network B associated with the virtual group address of 230.1.1.1 is different from another multicast group address (for example, 230.1.1.2 that requires fixing) , The multicast group address in the table 13b of FIG. 4 is rewritten to 230.1.1.3). FIG. 12 is a diagram showing an example of the multicast group address translation definition table 15a for A after the rewriting.

  The CPU 10c that executes these steps S404, S406, and S404 corresponds to the above-described first dynamic address changing unit.

  In this way, after the multicast group address of the multicast network B corresponding to the virtual group address in the multicast group address translation definition table 15a for A in FIG. 7 is switched to another, the CPU 10c determines that the A in FIG. Web page data is created based on the destination multicast group address conversion definition table 15a and the content information management tables 14a and 14b (step S402), and a response message including the web page data in the body is sent as a request in the multicast network A. It transmits to the original receiving terminal device 23 (or 24) (step S403).

  After receiving the response message (step S302), the receiving terminal device 23 that is the request source performs processing for displaying the web page on the display device (step S303). FIG. 13 is a diagram showing an example of the web page 41 generated based on the table 15a after the address conversion shown in FIG. As apparent from the comparison with FIG. 11, the contents of the title list are partially changed.

  In the relay device 10, after receiving the response message (step S404), in the multicast group address translation definition table 15a for A in FIG. 7, information indicating that delivery is in progress is recorded in the “fixed” field of all records. In the case (step S406; NO), the CPU 10c generates web page data and transmits a response message without rewriting the multicast group address corresponding to the virtual group address in the table 15a (steps S402 and S403). . Therefore, in this case, the title list of the video content listed as a clickable button on the web page 41 is not different from that displayed before (FIG. 11).

  Then, when the title list of the video content is presented through the web page 41 as shown in FIGS. 11 and 13 (step S303), when one of the clickable buttons 41a is clicked (step S304). NO, step S306; NO), the web browser of the receiving terminal device 23 (or 24) executes a process to be described later for displaying the stream content (step S307). Is requested to the relay device 10 for displaying the web page 41 in which is listed (step S301). If the end button is clicked on the web page 41 as shown in FIGS. 11 and 13 (step S306; YES), the web browser of the receiving terminal device 23 (or 24) ends the processing according to FIG.

  On the other hand, in the relay device 10, before the request message arrives (step S404; NO), if the timeout occurs (step S405; YES), the CPU 10c ends the processing (content list providing application 12) according to FIG.

  FIG. 14 is a diagram illustrating a flow of processing performed in the system when the receiving terminal device 23 (or 24) of the multicast network A acquires stream content.

  In executing step S307 of FIG. 10 described above, the receiving terminal device 23 (or 24) first transmits a multicast membership report (IGMP [Internet Group Management Protocol] Join) to a nearby rendezvous point router or bootstrap router. To do.

  Then, the rendezvous point router or the bootstrap router transmits a Join message including the multicast group address and the IP address as designation information to the upstream node (step S501). Note that the IP address specified by the specification information included in this Join message is set in the multicast network A when the video content provided by the source (encoder (ENC_A1, ENC_A2)) in the multicast network A is selected. The private IP address of the rendezvous point router or bootstrap router closest to the existing source (10,0.1.1, 10.0.1.2 in Fig. 1), but the source in the multicast network B (encoder (ENC_B1 to ENC_B6)) ) Is selected (when the lower two of the title lists are selected in FIGS. 11 and 13), the private IP address of the A IF 10a of the relay device 10 is selected. Become. In the following, processing when a Join message is sent to the relay device 10 will be described.

  In the relay device 10, when a Join message is sent from within the multicast network A, the CPU 10c executes the address conversion program included in the PIM-SM module 11a with the reception as a trigger. Then, the CPU 10c performs a process of converting the address described in the received Join message (step S601). Specifically, the CPU 10c rewrites the virtual group address in the Join message with the corresponding multicast group address based on the multicast group address conversion definition table 15a for A in FIG.

  The CPU 10c that executes step S601 corresponds to the first address conversion unit described above.

  After performing such address translation, the CPU 10c transmits a Join message from the B IF 10b to the source of the multicast network B (step S602).

  Note that the CPU 10c that executes step S602 corresponds to the first transmission unit described above.

  Then, in the multicast group address translation definition table 15a for A in FIG. 7, the CPU 10c switches the value of the “fixed” field of the multicast group address record described in this Join message to information indicating that delivery is in progress. (Step S603) Waits until a multicast packet is sent from the source.

  The source of the multicast network B that has received this Join message starts the process of sequentially transmitting the multicast packets constituting the stream content data to the receiving terminal device 23 (or 24) (step S701).

  Then, in the relay apparatus 10, the CPU 10c repeatedly performs processing such as reception of multicast packets from the source side, address translation, and transmission of multicast packets to the listener side (step S604). In the address conversion, the CPU 10c performs a process opposite to the process in step S601. That is, the CPU 10c rewrites the multicast group address in the multicast packet with the corresponding virtual group address based on the multicast group address translation definition table 15a for A in FIG.

  The CPU 10c that executes step S604 corresponds to the first address reverse conversion unit and the second transmission unit described above.

  When such a multicast packet is sent from the relay device 10, the rendezvous point router or bootstrap router of the multicast network B performs a process of delivering it between the receiving terminal devices 23 (or 24) (step S502). .

  In the receiving terminal device 23 (or 24), stream content data is generated from the received multicast packet, the data is decoded, and the stream content is reproduced and displayed.

  When an instruction to stop reproduction / display of stream content is input in the receiving terminal device 23 (or 24), the rendezvous point in which the leave group message (IGMP Leave) is near from the receiving terminal device 23 (or 24). Sent to a router or bootstrap router. Then, the rendezvous point router and the bootstrap router transmit a message instructing to stop the stream transmission of the multicast packet toward the source. Also when this message is sent to the source of the multicast network B, the relay device 10 performs address translation based on the multicast group address translation definition table 15a for A in FIG.

  In the present embodiment, the relay device 10 that connects the private multicast networks A and B includes a virtual group address that is less than the number of multicast group addresses set in the multicast network B for the multicast network A with a small video resource. (Corresponding to the first virtual group address described above) is set (tables 14a and 15a in FIG. 4 and FIG. 6). In such a setting state, the relay device 10 is connected from one network to the other network. Multicast packets are relayed to (steps S501, S502, S601 to S604, S701).

  As described above, when there is a request from the receiving terminal device 23 (or 24) that is a listener of the multicast network A (step S304; YES, S305), the relay device 10 The multicast group address of multicast network B assigned to the virtual group address is changed to another multicast group address (steps S404; YES, S406; YES, S407).

  For this reason, the listener of the multicast network A can use all the video resources of the multicast network B while limiting the number of virtual group addresses used in the multicast network A to such an extent that congestion does not occur. As a result, in the multicast network A, it is not necessary to change the communication device such as the layer 3 switch to a high-performance device, so that the multicast network B having a large number of video resources and the video resources can be used mutually. The introduction cost is not increased.

  In the present embodiment, the virtual group address (corresponding to the second virtual group address) set so that the receiving terminal device 37 of the multicast network B can use the video resources of the multicast network A is the multicast network. Since the number of video resources in A is small, the same number as the multicast group address of multicast network A is prepared and fixed without being dynamically changed (see FIGS. 6 and 8). Although not shown, the same processing as the processing shown in FIG. 14 (except for step S603) is performed (second address conversion unit, third transmission unit, second address). Equivalent to an inverse conversion unit and a fourth transmission unit). However, this virtual group address may also be set to be smaller than the number of multicast group addresses of the multicast network A. In this case, the same processing as the processing shown in FIG. 10 is also performed by the receiving terminal device 37 of the multicast network B, so that the multicast group address of the multicast network A is dynamically assigned to these virtual group addresses. Can be assigned (corresponding to a second list generation unit, a second list information transmission unit, and a second dynamic address change unit).

Configuration diagram of the computer network system of the present embodiment Configuration diagram of relay device The figure which shows an example of the data structure of RP information management table for A The figure which shows an example of the data structure of RP information management table for B The figure which shows an example of the data structure of the content information management table for A The figure which shows an example of the data structure of the content information management table for B The figure which shows an example of the data structure of the multicast group address translation definition table for A The figure which shows an example of the data structure of the multicast group address translation definition table for B The figure which shows the flow of the process performed in the said system, when a relay apparatus is selected as a rendezvous point from the bootstrap router of the B side. The figure which shows the flow of the process performed in the said system, when the receiving terminal device of the multicast network A acquires video content The figure which shows an example of the web page where the title list of the video contents is described The figure which shows the example of the multicast group address translation definition table for A after address rewriting The figure which shows the example of the web page produced | generated based on the table after the address conversion shown by FIG. The figure which shows the flow of the process performed in the said system, when the receiving terminal device of the multicast network A acquires stream content

Explanation of symbols

10 Relay device 10a IF for A
IF for 10b B
10c CPU
11 TCP / IP protocol suite 11a PIM-SM module 12 Content list providing application 13a RP information management table for A 13b RP information management table for B 14a Content information management table for A 14b Content information management table for B 15a Multicast group address for A Conversion definition table 15b Multicast group address conversion definition table for B

Claims (4)

A relay device for connecting first and second multicast networks configured by several PIM-compatible routers so as to be capable of multicast communication,
A plurality of network interfaces respectively connected to the routers of the first and second multicast networks;
In the second multicast network, the multicast group address is assigned to each of several multicast group addresses among the multicast group addresses assigned to the stream content in order for the listener to receive the stream content from the source. A first storage unit that stores a first virtual group address in association with each other so that a listener of the first multicast network can receive the stream content being stored,
When the network interface receives a multicast packet addressed to the first virtual group address from a router of the first multicast network, a multicast group address corresponding to the first virtual group address is obtained from the first storage unit. A first address conversion unit that reads and rewrites the first virtual group address in the multicast packet with the read multicast group address;
A first transmission unit for transmitting the multicast packet whose address has been rewritten by the first address translation unit to the router of the second multicast network through the network interface;
When the network interface receives a multicast packet from a router of the second multicast network as a response from a source in the second multicast network to which the multicast packet is transmitted from the first transmitter, the first A first virtual group address corresponding to the multicast group address described in the multicast packet is read from the storage unit, and the multicast group address in the multicast packet is rewritten to the read first virtual group address. 1 address reverse conversion unit,
A second transmission unit for transmitting the multicast packet whose address has been rewritten by the first address reverse conversion unit to the router of the first multicast network through the network interface;
When the network interface receives a request from any listener in the first multicast network, the stream assigned to the multicast group address respectively associated with the virtual group address in the first storage unit A first list generation unit for generating list information for displaying a list of contents;
When the first list generation unit generates list information, first list information transmission that transmits the generated list information to the listener that has transmitted the request in the first multicast network through the network interface. Part and
When the network interface receives an instruction to change the list contents from the listener , the multicast group address associated with the first virtual group address in the first storage unit is associated with the first virtual group address. is another not, change the luma multicast group address put in the second multicast network, comprising: a first dynamic address changing unit for generating the list information to the first list creation unit A relay device. The dynamic address changing unit
Of the multicast group addresses associated with the virtual group address in the first storage unit, when there is a multicast group address being used for multicast packet distribution, the virtual group associated with the multicast group address 2. The relay apparatus according to claim 1, wherein the multicast group address is changed for the remaining virtual group addresses excluding the addresses. In the first multicast network, for each of the multicast group addresses assigned to the stream contents so that the listener receives the stream contents from the source, the stream contents to which the multicast group address is assigned are sent to the second multicast network. A second storage unit for storing a second virtual group address for reception by a network listener in association with each other;
When the network interface receives a multicast packet addressed to the second virtual group address from a router of the second multicast network, a multicast group address corresponding to the second virtual group address is obtained from the second storage unit. A second address conversion unit that reads and rewrites the second virtual group address in the multicast packet with the read multicast group address;
A third transmitter for transmitting the multicast packet whose address has been rewritten by the second address translator to the router of the first multicast network through the network interface;
When the network interface receives a multicast packet from a router of the first multicast network as a response from the source in the first multicast network to which the multicast packet is transmitted from the third transmission unit, the second packet A second address reverse conversion unit that reads a second virtual group address corresponding to the multicast group address from the storage unit and rewrites the multicast group address in the multicast packet with the read second virtual group address;
2. The fourth transmission unit according to claim 1, further comprising: a fourth transmission unit configured to transmit the multicast packet whose address has been rewritten by the second address reverse conversion unit to the router of the second multicast network through the network interface. 2. The relay device according to 2. The second storage unit stores a second virtual group address in association with each of several multicast group addresses among the multicast group addresses of the first multicast network,
Furthermore,
When the network interface receives a request from any listener in the second multicast network, the stream assigned to the multicast group address respectively associated with the virtual group address in the second storage unit A second list generation unit for generating list information for displaying a list of contents;
When the second list generation unit generates list information, second list information transmission that transmits the generated list information to the listener that has transmitted the request in the second multicast network through the network interface. Part and
When the network interface receives an instruction to change the list contents from the listener , the multicast group address associated with the second virtual group address in the second storage unit is associated with the second virtual group address. is another not, change the luma multicast group address put on the first multicast network, characterized in that it comprises a second dynamic address changing unit for generating the list information to the second list generating unit The relay apparatus according to claim 3.