JP4852027B2 - Multicast communication system, storage device used in multicast communication system, and multicast communication method - Google Patents

Description

  The present invention relates to a multicast communication system, a storage device used in the multicast communication system, and a multicast communication method.

  Multicast means that communication data is transmitted from a source terminal to a specific IP address between terminals that perform IP communication, and a plurality of routers connecting the terminals transfer the communication data to receive the data. This is a data transmission method for distributing communication data to a terminal.

  Conventionally, in IP multicast communication, data transmitted from a transmission source terminal is duplicated at each router and transferred between routers to reach a reception terminal that desires reception. Packets lost during transfer are compensated for by restoration at the receiving terminal side, retransmission at the source terminal or relay router, and the like.

  However, in this situation, when there is a receiving terminal connected to a network with poor communication quality, the transmission source terminal needs to hold a considerable amount of transmitted data for a certain receiving terminal. . When multiple source terminals transmit data to the same multicast destination at the same time, it is connected to one or more lines connecting the router as the destination node of the multicast transfer path and the router on the upstream side of this router. Requires a band according to the number of transmission source terminals.

  For this reason, multicast using a method that aggregates information of the same content is also performed, but this method uses a reception completion message (ACK) or reception failure message (NACK) that the receiving terminal throws to the source terminal or relay router. The purpose is to reduce as much as possible.

  As for multicast routing methods, PIM-DM (Protocol Independent Multicast-Dense Mode) method that creates a large tree for each sender with the sender as the root and the relay as a rendezvous point (RP) A PIM-SM (Protocol Independent Multicast-Sparse Mode) method is known in which a multicast message to a certain destination is always routed through the router.

  There are advantages and disadvantages to these methods. In short, the PIM-DM scheme requires a certain amount of resources to form and maintain a tree, but has the advantage that the shortest path from each source terminal to the receiving terminal can be set.

  On the other hand, in the PIM-SM system, a multicast packet of a receiving terminal that exists within a transfer distance of 1 hop from the transmission source terminal always passes through the rendezvous point, so there is a possibility that the route becomes a detour. On the other hand, the router only needs to maintain one tree information with the rendezvous point as the root and the receiving terminal as the leaf, and even if multiple source terminals are provided, packets transferred between routers under the rendezvous point are not Since it is transferred along the same route, there is an advantage that an intuitive estimation of the amount of information flowing through the route becomes easy.

As for the multicast packet forwarding method in the router device, conventionally, a multicast packet forwarding method has been proposed which can efficiently handle multicast packet forwarding and discarding and can efficiently perform management control of multicast packets to be discarded. (See Patent Document 1).
JP 2006-324981 A

  However, in the conventional multicast communication system using the PIM-SM method, if the communication quality of the network in the middle of transfer is poor, it takes time for retransmission control, and sufficiently high-quality image, audio, and video data is sent. There is a problem that can not be.

  In various sites such as a blog describing a diary, a web page where news and articles can be viewed, or a web page where posted videos can be viewed, a large number of receiving terminals join the multicast group to obtain information from the site. Will be delivered. When receiving terminals receive data by multicast from a plurality of sites that distribute similar articles, the receiving terminals receive substantially the same text, the same image, or the same video from these sites. When the number of senders increases, the terminal receiving terminal receives a plurality of pieces of information having the same contents but different titles. Transfer of information data having substantially the same contents is redundant and places a heavy burden on the network.

  Accordingly, in view of the above-described problems, the present invention provides a multicast communication system and a multicast communication system capable of preventing unnecessary information from being generated in a receiving terminal and reducing a load on the network in the multicast communication system. It is an object of the present invention to provide a storage device and a multicast communication method used for the above-mentioned.

In order to solve such a problem, according to one embodiment, a first packet is transmitted to a multicast address that includes one or more types of data among text data, image data, audio data, and video data as information data . And a plurality of second terminals respectively registered in the multicast group, and the information data from the first terminal is accumulated and a multicast packet including the information data is addressed to the plurality of second terminals A router device that transmits the same transfer path as a distribution point for the multicast address via a network, the router device receiving the packet from the first terminal, and a lack of received data A retransmission request unit that determines the presence or absence of the packet and requests retransmission to the first terminal; A summary of the information data is created by reducing a part of the text data, creating thumbnails obtained by reducing the image data and the video data, and extracting metadata from the image data, the audio data, and the video data. Summarizing means, the information data received by the receiving unit, the storage device storing the summary created from the information data by the summary generating means, and the received data by the receiving unit are stored in the storing device A comparison unit for comparing whether or not the information data is duplicated, multicast means for multicasting the summary to the multicast address, and receiving a multicast summary of the plurality of second terminals Based on the distribution request from the second terminal The information data stored in the storage device to respond, from the second sending means for sending to the terminal, wherein the router device of redundant data having the substantially same content to the plurality of second terminals There is provided a multicast communication system characterized in that transmission to the network is stopped .

According to another embodiment, a first terminal that transmits text data, image data, a packet to multicast address to one or more of data among the audio data and video data is included as the information data, respectively A plurality of second terminals registered in the multicast group, and the information data from the first terminals is accumulated, and multicast packets including the information data are distributed to the plurality of second terminals to the multicast address. A transmission / reception unit that transmits / receives data to / from a router device that transmits via the network on the same transfer path as a point, and a retransmission request that determines whether the received data is missing and requests retransmission to the first terminal And part of the text data from the packet received by the transceiver A summary creation means for creating a summary of the information data by creating a thumbnail by reducing the image data and the video data, and extracting metadata from the image data, the audio data, and the video data; The information data received by the storage unit and the storage device that stores the summary created from the information data by the summary creation means, and the reception data received by the transmission / reception unit overlaps the information data stored in the storage device A comparison unit for comparing whether or not the data is to be transmitted, wherein the transmission / reception unit multicasts the summary to the multicast address and receives the multicast summary of the plurality of second terminals. The distribution request from the second terminal was received and received by the second terminal It sends the information data stored in the storage device corresponding to the Mali to the second terminal of this, from the router device of redundant data having the substantially same content to the plurality of second terminals to the network There is provided a storage device used in a multicast communication system characterized in that transmission is stopped .

According to another embodiment , the first terminal is one of text data, image data, audio data, and video data addressed to a multicast address of a multicast group registered by a plurality of second terminals. Transmitting a packet including the above data as information data, a step in which a router selected as a distribution point for the multicast address determines whether or not the received data is missing, and the router in the network A part of the text data from the packet received from the first terminal, a thumbnail created by reducing the image data and the video data, and the image data, the audio data and the video data from Create a summary of the information data by extracting metadata A step, a step of storing the information data and the summary in the storage device, the method comprising receiving data to compare whether the data overlaps with the information data stored in the storage device, the router device, Multicasting the summary to the multicast address; receiving the distribution request from the second terminal from which the router device has received the multicast summary among the plurality of second terminals; Based on the distribution request, the router device sends the information data stored in the storage device corresponding to the summary received by the second terminal to the second terminal via the network through the same transfer path. the router of redundant data and step comprises, with the substantially same contents to the plurality of second terminals Multicast communication method characterized by stopping the delivery to put al the network is provided.

  According to the present invention, in a multicast communication system, generation of useless information is prevented in terminals registered in a multicast group, and the load on the network is reduced.

  Hereinafter, a multicast communication system, a storage device used in the multicast communication system, and a multicast communication method according to an embodiment of the present invention will be described with reference to FIGS. In the drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram of a multicast communication system according to an embodiment of the present invention. This multicast communication system extracts data from received packets by transmitting terminals 1a to 1e that transmit packets, routers 2a to 2g that relay and forward packets transmitted from these terminals 1a to 1e, and this data Routers 3a and 3b that transfer packets containing copied data and receiving terminals 4a to 4i that receive multicast packets and receive data.

  These routers 3a and 3b are router devices. An IP network 5 is formed by the routers 3a and 3b and the routers 2a to 2g, and messages are exchanged by IP multicast in the IP network 5.

  The transmission source terminals 1a to 1e are all first terminals, and a personal computer or a workstation is used for them. The transmission source terminals 1a to 1e are connected to the transmission source terminals 1a to 1e, respectively, with multicast packets including one or more types of data among text data, image data, audio data, and video data as information data. Send to the router.

  Each of the receiving terminals 4a to 4i is a second terminal. A personal computer or a portable terminal is used as the receiving terminals 4a to 4i. Of the receiving terminals 4a to 4i, the receiving terminals 4a, 4b, and 4c have registered in advance in the routers 3a and 3b that they wish to distribute the edited multicast data.

  FIG. 2 is a functional block diagram of the router 3a having the storage device according to the present embodiment. The router 3a includes a data transmitting / receiving unit 7 for exchanging data with an external device via an interface unit (I / F unit) 6, a process for transferring received data to another router as it is, and received data Is provided with a data identification unit 8 that determines whether to perform one of the processes to be accumulated after performing the aggregation process, and a storage device 9 that stores the data subjected to the aggregation process.

  The data identification unit 8 is data for which transfer processing is immediately performed without performing storage processing on received data, or data for which storage processing including aggregation processing of this data is performed on received data. To identify. The data identified by the data identifying unit 8 as not being accumulated is transferred as it is as shown in FIG. The data identification unit 8 reads the extension of the received data that has been determined to be stored, and the received data is text data or multimedia data other than text data such as image data, audio data, or video data. I try to determine if it exists. The data type is determined by determining whether the data identification unit 8 can extract the text of the text. Alternatively, this determination is also made by determining whether or not only a data string is listed.

  The storage device 9 includes a storage device that stores data, a CPU (Central Processing Unit), a ROM, and a RAM. These CPU, ROM, and RAM realize the function of summary creation means for performing data processing such as summary creation and data aggregation described below. The data transmission / reception unit 7 and the CPU, ROM, and RAM realize the function of multicast means for multicasting the summary. The function of the sending means is realized by the data transmitting / receiving unit 7 and the function of storing and managing information on the transfer path stored in the router 3a. The storage device 9 also has a retransmission control function for managing the received data sequence and performing retransmission control.

  The storage device of the storage device 9 stores, as text data, a sentence such as a news article, a sentence such as a blog, or a source code described using XML or HTML. The storage device also stores metadata indicating the size of the file, when the text file was created, and who created the text file. The storage device stores image, audio, and video data. The storage device also stores metadata including the size, creation date and time, summary created by the creator, or the like for each of the image, audio, and video data. The metadata is received together with data such as text data and images.

  Text data, image data, audio data, or video data stored in a storage device is stored for a certain period for retransmission after an expiration date is set.

  Further, the storage device 9 generates summary data that represents a summary of the contents of the received data, and this summary data is also stored in the storage device of the storage device 9. The summary about text data refers to a part of text data. The summary about images and moving images refers to thumbnail images obtained by reducing the metadata itself or the original data of images and moving images. The summary about audio and music refers to the metadata itself and a summary created by the creator. The data identification unit 8 aggregates received data by generating summary data having a data amount smaller than the data amount of the received data. That is, the storage device 9 stores original information data and summary data aggregated from the information data.

  The router 3a compares the received data with data that overlaps the information data stored in the storage device 9. The router 3 a includes a text comparison unit 10 that compares the received data determined as text data by the data identification unit 8 and the text data stored in the storage device 9, and an image, video, or the like other than text by the data identification unit 8. A metadata comparison unit 11 that compares the received data determined as the data of the image and data such as images and videos stored in the storage device 9. The text comparison unit 10 compares whether or not the accumulated text is included in the text of the received text data. This comparison is performed, for example, by searching for text data in the storage device and a part of the received text data. The metadata comparison unit 11 compares whether there is metadata that matches the accumulated metadata in the metadata of the received data. This comparison is performed by calculating a hash value such as MD5 for both, and comparing the results obtained by the calculation. The functions of the text comparison unit 10 and the metadata comparison unit 11 are realized by a CPU, a ROM, and a RAM.

  As a result, the received data determined to be stored in the data identification unit 8 is further checked for its extension, and divided into whether to perform text comparison or metadata comparison, and can be aggregated respectively. It is checked whether it exists. As shown in (ii) of FIG. 2, it is determined whether there is a duplicate sentence in the text data. As shown in (iii) of FIG. 2, it is determined whether image or video data has duplicate metadata. As a result, when multiple copies of the same video are sent, redundant videos are deleted, duplicate redundant videos are accumulated, and the same video data is not transferred excessively. ing.

  Each stored data is transmitted to the receiving terminals 4a to 4i periodically, and is transmitted in response to a request from the receiving terminals 4a to 4i.

  Further, when it is determined that the data received from the transmission terminals 1a to 1e is missing, the router 3a sets a transmission request unit (retransmission request unit) 12 that requests the transmission terminals 1a to 1e to retransmit the missing data. I have. The determination of whether or not the received data is lost is performed by the retransmission control unit in the storage device 9. The transmission request unit 12 determines that the data that has reached the storage device 9 is incomplete due to occurrence of packet loss or the like between any of the transmission source terminals 1a to 1e and the router 3a, and from the storage device 9 In each case of receiving a command requesting retransmission of necessary data and receiving a reception request sent irregularly from the receiving terminals 4a to 4i, the other terminal is notified in accordance with each case. On the other hand, the data stored in the storage device 9 is transmitted. Both when a packet loss is detected and when a command from the storage device 9 is notified, a retransmission request is transmitted to one of the transmission source terminals 1a to 1e as shown in (iv) of FIG. It has become so. When a reception request is received from any of the receiving terminals 4a to 4i, as shown in (v) of FIG. 2, the accumulated data is transmitted to any of the receiving terminals 4a to 4i. .

  The configuration of the router 3b in FIG. 1 is the same as the configuration of the router 3a. The configuration of a router having a storage function (not shown) is the same as that of the router 3a.

  In the multicast communication system according to the present embodiment, these routers 3a and 3b are determined so that the routers 3a and 3b function as rendezvous points. The routers 3a and 3b, together with the routers 2a to 2g, perform PIM-SM routing between these routers.

  FIG. 3A is a diagram for explaining PIM-SM. Elements having the same reference numerals as those described above among the reference numerals shown in this figure represent the same elements. A distribution tree having the router 3a as a root and a plurality of receiving terminals including the receiving terminals 4d, 4e, 4a, and 4b as leaves is determined by the router 3a, and information on this distribution tree constitutes the network 5 from the router 3a. Distributed to other routers. The router 3a is notified that the receiving terminal 4b desires to receive data. When the source terminal 1a transmits data to a specific multicast address, the router 3a transfers the data only to the receiving side terminal registered in the multicast group by the multicast member management protocol. From the source terminal 1a to the router 3a, the packet passes through an arbitrary transfer path. Since all packets pass through the same transfer path between routers 3a and downstream routers, an increase in the transfer path is suppressed.

  There are two types of terminals or devices that perform multicast communication: IPv4 terminals that use the IPv4 scheme as communication protocols and IPv6 terminals that use the IPv6 scheme as communication protocols. In the multicast communication system according to this embodiment, these two types are used. A mixture of terminals is available.

  FIG. 3B is a diagram showing a multicast address system in IPv6. The total number of bits of the IP address in IPv6 is 128 bits. If the upper 8 bits of the IP address are all 1, this means that this IP address is a multicast address. In short, this IP address is an address starting with FFxx ::. In the current version of the protocol, the meaning of the address is determined using only the 12th bit out of the 4th bit from the 9th bit to the 12th bit. If the 12th bit is 0, it is permanent. Means that the address is temporarily assigned if the bit is “1”. Four bits from the 13th bit to the 16th bit represent a scope and represent an effective range of the multicast address.

  The 112th bit after the 17th bit is a group ID, and a multicast address is identified in the same scope by this group ID. As for an IP address in IPv4, an address whose upper 4 bits are 1110 out of the total number of 32 bits is assigned as a multicast address.

  In the multicast communication system according to the present embodiment, when two routers 3a and 3b including the storage device 9 or more routers are provided, one database is shared and managed between the routers. The data is stored in a data space defined on the same database. This data space is a storage area shared between the storage device 9 of the router 3a and the storage device 9 of the router 3b. Data is exchanged between the storage devices 9 due to a change such as increase / decrease of members participating in multicast, and the contents of the data space can be changed.

  In this multicast communication system, a single destination is used as a multicast destination in multicast using a data space. At that time, the data type and the name of this data are designated and transmitted between the terminals or routers. This makes it possible to distinguish information stored in a database defined in the data space using the data type and data name, so that information can be easily aggregated and integrated. Has been.

  The router 3a of the multicast communication system according to the present embodiment having such a configuration handles the arrived data according to the following flowchart.

  FIG. 4 is a flowchart for explaining the data processing operation of the router 3a. In step S1, the interface unit 6 receives data from any of the transmission source terminals 1a to 1e. In step S2, the data identification unit 8 determines whether the received data is data to be transferred as it is without performing processing such as accumulation, and the data identification unit 8 determines that the data is to be transferred as it is In step S3, the data transmitting / receiving unit 7 transfers the received data as it is.

  If the data identification unit 8 determines in step S2 that the received data is not data to be transferred as it is, it passes through the No route, and in step S4, the retransmission control unit of the storage device 9 determines whether the data is missing. Determine. If it is determined in step S4 that the data is missing, it passes through the Yes route, and in step S5, the transmission request unit 12 transmits a retransmission request to one of the transmission source terminals 1a to 1e. While it is determined that there is a missing data, the processes of step S4 and step S5 are performed.

  If it is determined in step S4 that there is no missing data, the route is No, and in step S6, the data identification unit 8 identifies the data type from the extension of the received data. If the data identification unit 8 determines that the received data is text data, the text data comparison unit 10 compares the received text data with the stored text data in step S7 through the route attached to the text data. . In step S6, if the data identification unit 8 determines that the received data is image data, video data, or audio data, the metadata comparison unit 11 passes the route attached with the image, video, and audio data in step S8. The received metadata is compared with the accumulated metadata.

  Subsequently, in step S9, the storage device 9 stores received data, creates a summary, or collects data based on the comparison results in the processes in steps S7 and S8. Further, the generated summary is periodically distributed from the storage device 9 (step S10).

  After step S3 and step S10, in the IP network 5, data is transferred according to a multicast tree with the storage device 9 as a rendezvous point, and multicast is performed (steps S11 and S12).

  In step S13, the data transmitting / receiving unit 7 of the router 3a monitors whether or not the received data loss notification is received from any one or more of the receiving terminals 4a to 4i. As such, the process ends. In step S13, when the data transmitting / receiving unit 7 receives a notification of the loss of received data from any of the receiving terminals 4a to 4i, the Yes route is passed, and in step S14, the transmission requesting unit 12 determines the receiving terminals 4a to 4i. A packet is generated for resending data that is missing from either. This packet is transmitted by unicast (step S15). After being unicast, the data transmission / reception unit 7 of the router 3a continues to monitor whether or not the notification of the lack of received data has been received from any of the receiving terminals 4a to 4i through the route labeled A (step) S13).

  The operation of the router 3b and other routers having a storage function (not shown) are the same as the operation of the router 3a.

  Since the routers 3a and 3b distribute this data after the received data is completely prepared, an increase in the number of retransmission requests is prevented. Accordingly, the amount of data on the transfer path from the receiving terminals 4a to 4i to the router 3a can be reduced.

  In the multicast communication system according to the present embodiment, first, any one of the transmission source terminals 1a to 1e transmits data to the multicast address defined by FIG. Then, one of the routers 3a and 3b having a storage function on the network 5 is designated as a rendezvous point and received.

  FIG. 5 is a diagram showing an example of a transfer path when data is stored in the storage device 9 according to the present embodiment. Data is transmitted from each of the transmission source terminals 1a to 1e to the multicast address of the router 3a having a storage function. Each data is transferred between routers and stored in the storage device 9 of the router 3a. Thereby, data aggregation and integration are performed.

  Depending on the designation of the transmission source, the message is directly transferred as a multicast message without being accumulated, or accumulation or aggregation processing is selected. Data that is allowed to be stored is processed in the storage device 9 by creating a summary, deleting similar information by metadata, and the like.

  FIG. 6 is a diagram illustrating an example of a transfer path when data is transmitted from the router 3b to the receiving terminals 4a to 4i. The connection example is appropriately changed from the example of FIG. The summary created based on the accumulated data is periodically multicast toward the receiving terminals 4a to 4i of the multicast group.

  The receiving terminals 4a to 4i that have received the summary can acquire the multicast stored in the storage device 9 as needed, and can also request periodic multicast distribution. The data is also sent to the receiving terminals 4a to 4i by receiving a request from the recipient.

  Next, a method for changing a router having a storage function will be described.

  The multicast routing used in the multicast communication system according to the present embodiment can be considered as an existing PIM-SM system. This method is a type in which one of the transmission source terminals 1a to 1e designates a router through which data always passes, and forms a multicast tree from the designated router to a plurality of routers under the router. This is a path control method.

  On the data space, the router having a storage function as a rendezvous point in the PIM-SM is determined by the receiving terminals 4a to 4i that desire to distribute information. When a plurality of routers having a storage function are provided, among these routers, a router that can form the most efficient distribution tree for the transfer path between the receiving terminals 4a to 4i is designated as a rendezvous point. . The rendezvous point dynamically changes depending on the joining status of the receiving terminals 4a to 4i to the multicast group, and distribution data is transmitted and received between routers having a storage function. In addition, the rendezvous point installation points are intentionally distributed so that the rendezvous points for sending a plurality of multicast messages are not biased toward a single router with a storage function.

  FIG. 7 is a diagram for explaining a change from the router 3b to the router 3c. The connection paths between the routers 3a to 3c and the routers 2a to 2c are appropriately changed from the example of FIG.

  First, the transmission source terminal 1 a transmits data to the multicast address assigned to the router 3 b having the storage device 9. When the number of transmission-side terminals that transmit data to the same multicast address (router 3b) increases, congestion may occur in the transmission path near the router 3b. The transmission source terminal 1a and the router 3b measure RTT (Round Trip Time), which is a round trip time between the transmission terminal 1a and the reception terminals 4a to 4f, and detect communication quality. RTT and communication quality values are exchanged. When these values deteriorate below a predetermined threshold, the transmission source terminal 1a determines that the route to the router 3b used so far is congested, and the transmission source terminal 1a is a router having another storage device 9. The multicast address that has been used up to that point is assigned to 3c, and data accumulation and transfer are continued. As a result, the router having the storage function is dynamically changed.

  The selection of a router having a storage function as to which router to select is that the storage devices 9 in the router corresponding to this multicast communication system send control data to each other and select a router that is not affected by congestion. Is done by. Even if the transfer path is a detour, communication efficiency is ensured by balancing the line utilization rate across the entire network.

  For example, when a situation occurs in which the moving image data cannot reach the storage device 9, the cause may be network disconnection, traffic volume, access line status, and the like. In the multicast communication system according to the present embodiment, a multicast address is assigned to each router having a storage function, and the storage devices 9 exchange data with each other's storage device 9 to exchange data addresses. change. The correspondence between the multicast address and the device address of the router having the storage function is not uniquely determined, and this correspondence is dynamically changed.

  In the multicast communication system according to the present embodiment, the transmission source terminal 1a and the reception terminals 4a to 4f can be completely disconnected. The transmission source terminal 1a multicasts this data only by managing the arrival of data to the router having the storage function. Communication between the routers 3a, 3b and 3c having the storage function and the receiving terminals 4a to 4f is performed by these routers 3a, 3b and 3c. In order to realize that the data surely reaches the receiving terminals 4a to 4f, the multicast has a function of retransmission control in which a necessary packet is sent again. In this multicast communication system, two-stage retransmission control is performed between the transmission source terminal 1a and the storage device 9 in the router and between the storage device 9 and the reception terminals 4a to 4f. More reliable data arrival is realized.

  FIG. 8 is a diagram for explaining a retransmission control method performed when data is accumulated from the transmission source terminal 1a to the router 3b. FIG. 9 is a diagram for explaining a retransmission control method performed when data is distributed from the router 3b to the receiving terminals 4a to 4f. In the transmission section between the transmission source terminal 1a of FIG. 8 and the router 3b having the storage device 9, the transmission source terminal 1a waits for an ACK from the router 3b after transmitting data, and this ACK does not come. Resend periodically. When the router 3b detects a packet loss or the like, the router 3b transmits a NACK to the transmission source terminal 1a and requests the transmission source terminal 1a for necessary missing portion data. When receiving the reception failure message, the transmission source terminal 1a performs retransmission. When the reception of the message is completed, the router 3b transmits an ACK to the transmission source terminal 1a. In FIG. 9, the example of the retransmission control in the transmission section between the router 3b having the storage device 9 and the receiving terminal 4c is the same as the example of the retransmission control in FIG.

  As a result, when a message with the total number of packets of 1 is lost during transmission, it is dealt with by performing periodic transmission. When a message with a large total number of packets is lost during transmission, the loss of data is detected by monitoring the sequential number.

  Further, the routers having the storage function exchange information with each other, whereby the transfer route is managed in the entire network. That is, the transmission source terminals 1a to 1e do not need to know the transfer path from the transmission source terminals 1a to 1e to the router built in the storage device 9 as a temporary destination. It is only necessary to add to the packet data metadata for categorizing each type of data such as the type of data, the name of the data, and data indicating what the information content relates to. The destination setting is performed by the storage device 9. One that actually functions as a multicast address is sufficient when viewed from the transmission source terminal, and the contents described in the metadata are used as a destination to substitute for the multicast address.

  FIG. 10 is a diagram illustrating an example of metadata attached to data handled by the router device having the storage function according to the present embodiment. The types of data handled include simple text data, HTML format files, XML format files, audio data and video data that can be identified by extension. When text data having the same type and the same name is sent to the same destination, a summary is created by extracting several lines of data from the text data. When multimedia data with the same type and name is sent to the same destination, ie, image, video, and audio data, a summary is created by extracting metadata from this multimedia data. . Each time new information is stored in the storage device 9, the summary is updated. The updated summary is periodically multicast from the storage device 9 to the receiver side. The receiving terminals 4a to 4i acquire the summary, and the receiving terminals 4a to 4i transmit a request to the storage device 9 in order to acquire necessary information.

  Information integration is performed by designating in advance the type of data received by the receiving resource such as the receiving address or the model of the receiving terminals 4a to 4i, and handling only the same type of data.

  As an example of information integration, a mechanism for determining image data based on metadata will be described with reference to FIGS. FIG. 11 is a diagram for explaining a mechanism for determining the identity of a file using metadata.

  FIG. 11 shows images of three files. As indicated by the balloon, these three files 13, 14, and 15 each have metadata. These files 13 to 15 have the same file name. The file size of the file 13 and the file size of the file 15 are the same, and the file size of the file 14 is different from the file sizes of the files 13 and 15. The file name of the file 13 and the file name of the file 14 are the same, and the file name of the file 15 is different from the file names of the files 13 and 14. Here, when determining whether the files 13 to 15 match or not using metadata other than the file name, the file 13 and the file 15 are regarded as the same, and the two files 13 and 15 are more The old file 15 is deleted. Only the newer file 13 is stored in the storage device 9 as transmission data.

  Accordingly, the storage device 9 performs a process of aggregating duplicate data among data of the same data type.

  In addition, the routers 3a and 3b provide a mechanism that not only summarizes the same type of information but also does not reduce the content to be transmitted and reduces the total amount of information. FIG. 12 is a diagram for explaining a mechanism for transmitting a summary using metadata.

  The storage device 9 reduces the size of text data by reducing data in which the same sentence is listed, such as a summary of a certain site or citations of articles on some site. As for data with a large file size such as images and videos, as shown in FIG. 12, only metadata or thumbnail data is transmitted as a summary during periodic information distribution, and the receiving terminals 4a to 4i receive the summary. When it is necessary to receive the actual data after acquiring the data, it is possible to prevent a large amount of data from periodically flowing through the IP network 5 by executing the procedure of requesting the storage device 9 to distribute the data again. .

  Accordingly, the storage device 9 performs processing for reducing the amount of information data, such as partial text reduction, image thumbnail creation, and metadata extraction for data with a large amount of information.

  As described above, according to the multicast communication system according to the present embodiment, when the contents of articles such as news information on a web site and diary pages such as blogs can be distributed innumerably, the storage device 9 is The routers 3a and 3b having the distribution data temporarily store the distribution data and reduce the data amount in the storage device 9 to some extent, and then the routers 3a and 3b notify the receiving terminals 4a to 4i. The original data itself is not sent to the recipient, but data with a smaller amount of data is sent in the form of a notification. Then, the original data is sent from the storage device 9 to the receiving terminals 4a to 4i that wish to be distributed again.

  As an example to which this multicast communication system is applied, it is used for a system that distributes various kinds of recommended information, notifications of changes such as changes in the contents of a specific site, etc. that do not always need to be continuously viewed by the receiver. it can. In other words, this multicast communication system can be used in such a way that the receiver only has to obtain the desired information when the receiver wants.

  Thus, according to the multicast communication system, the storage device 9 used in the multicast communication system, and the multicast communication method according to the present embodiment, it is possible to stop a large amount of extra information from flowing through the IP network 5, and In a summarized form, data is transmitted only when the receiver wants it, so that it is possible to reduce the receiving terminals 4a to 4i from receiving redundant data.

  Further, according to the multicast communication system according to this embodiment, stable network line quality can be maintained, so that the load on the IP network 5 can be reduced and a sufficiently high-quality image can be sent to the receiver. become.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. The number of routers having the storage device 9 may be one for one IP network 5 or three or more for one IP network 5. When a plurality of routers with storage devices are provided in the IP network 5, these routers with storage devices are provided so as to be distributed at respective locations. In this case, the handled multicast address can also be exchanged among the plurality of storage devices 9. By doing so, it is possible to prevent a plurality of multicast messages from concentrating on one router with a storage device, and to distribute the load of the IP network 5.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a block diagram of the multicast communication system which concerns on one Embodiment of this invention. It is a functional block diagram of a router device having a storage device according to an embodiment of the present invention. (A) is a figure for demonstrating PIM-SM, (b) is a figure which shows the system of the multicast address in IPv6. It is a flowchart for demonstrating the operation | movement of the data processing of a router apparatus. It is a figure which shows an example of the transfer path | route when data are accumulate | stored in the router apparatus which has an accumulation | storage apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the transfer path | route when data are transmitted to a receiving terminal from the router apparatus which has an accumulation | storage device concerning one Embodiment of this invention. It is a figure for demonstrating the change from the router apparatus which has an accumulation | storage apparatus which concerns on one Embodiment of this invention to another router apparatus. It is a figure for demonstrating the retransmission control method performed when data are accumulate | stored from a transmission source terminal to a router apparatus. It is a figure for demonstrating the retransmission control method performed when data are delivered from a storage device to a receiving terminal. It is a figure which shows an example of the metadata provided to the data which the router apparatus which has a storage apparatus which concerns on one Embodiment of this invention handles. It is a figure for demonstrating the mechanism in which a router apparatus judges the identity of a file using metadata. It is a figure for demonstrating the mechanism in which a router apparatus transmits a summary using metadata.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a-1e ... Transmission source terminal (1st terminal), 2a-2g ... Router, 3a, 3b ... Router (router apparatus), 4a-4i ... Receiving terminal, 5 ... IP network (network), 6 ... Interface part, DESCRIPTION OF SYMBOLS 7 ... Data transmission / reception part, 8 ... Data identification part, 9 ... Storage apparatus, 10 ... Text comparison part, 11 ... Metadata comparison part, 12 ... Transmission request part, 13-15 ... File.

Claims (5)

A first terminal that transmits a packet including text data, image data, audio data, and video data as information data to a multicast address , and a plurality of second terminals that are respectively registered in the multicast group And the multicast packet including the information data is transmitted to the plurality of second terminals as a distribution point for the multicast address through the same transfer path via the network. A router device,
This router device
A receiving unit for receiving the packet from the first terminal;
A retransmission request unit that determines whether or not the received data is missing and requests retransmission to the first terminal;
Summary of the information data by reducing a part of the text data from the packet, creating a thumbnail in which the image data and the video data are reduced, and extracting metadata from the image data, the audio data, and the video data A summary creation means for creating
A storage device for storing the information data received by the receiving unit and the summary created from the information data by the summary creation means;
A comparison unit for comparing whether the data received by the reception unit is data that overlaps the information data stored in the storage device;
Multicast means for multicasting this summary to the multicast address;
Based on the distribution request from the second terminal that has received the multicast summary among the plurality of second terminals, the information data stored in the storage device corresponding to the summary is stored in the second terminal. Delivery means for delivering to , and
A multicast communication system characterized in that transmission of redundant data having substantially the same contents to the plurality of second terminals from the router device to the network is stopped .   The multicast communication system according to claim 1, wherein the summary creation unit performs a process of collecting duplicate data among data of the same data type or a process of reducing an information amount of the information data. A first terminal that transmits a packet including text data, image data, audio data, and video data as information data to a multicast address , and a plurality of second terminals that are respectively registered in the multicast group And the multicast packet including the information data is transmitted to the plurality of second terminals as a distribution point for the multicast address through the same transfer path via the network. A transmission / reception unit for transmitting / receiving data to / from the router device,
A retransmission request unit that determines whether or not the received data is missing and requests retransmission to the first terminal;
Reduction of part of the text data from the packet received by the transmission / reception unit, creation of thumbnails obtained by reducing the image data and the video data, and metadata from the image data, the audio data, and the video data Summary creation means for creating a summary of the information data by extraction;
A storage device for storing the information data received by the transceiver and the summary created from the information data by the summary creation means;
A comparison unit that compares whether the data received by the transmission / reception unit is data that overlaps the information data stored in the storage device ,
The transmission / reception unit multicasts the summary to the multicast address, receives a distribution request from the second terminal that has received the multicast summary among the plurality of second terminals, and receives the second request. It sends the information data stored in the storage device corresponding to the summary terminal receives the second terminal of this, from the router device of redundant data having the substantially same content to the plurality of second terminals A storage device used in a multicast communication system, wherein transmission to the network is stopped . A packet in which at least one type of data among text data, image data, audio data, and video data is included as information data is addressed to a multicast address of a multicast group registered by a plurality of second terminals. Sending, and
A router device selected as a distribution point for the multicast address determines whether there is a lack of received data;
The router device reduces a part of the text data from the packet received from the first terminal via the network , creates a thumbnail obtained by reducing the image data and the video data, and the image data and the audio. Creating a summary of the information data by extracting data and metadata from the video data;
Storing the information data and the summary in a storage device ;
Comparing whether received data is data that overlaps the information data stored in the storage device;
The router device multicasts the summary to the multicast address;
The router device receiving a distribution request from a second terminal that has received a multicast summary of the plurality of second terminals;
Based on the distribution request, the router device transfers the information data stored in the storage device corresponding to the summary received by the second terminal to the second terminal via the network through the same transfer path. comprising a step of transmitting, a,
A multicast communication method characterized in that transmission of redundant data having substantially the same contents to the plurality of second terminals from the router device to the network is stopped .   The multicast communication method according to claim 4, wherein the router device periodically transmits the summary to the multicast address.

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