KR20060023687A - Method and system for voting optimum route in multicasting - Google Patents

Abstract

According to the present invention, when an abnormality such as delay or interruption of a video stream occurs while receiving multimedia data of a predetermined size or more multicasted from a main server, an audio transmission path having the fastest transmission speed among a plurality of audio transmission paths is generated. Is set as a video transmission path, but the transmission path is set through level up, level down, and level shift according to the delay value and the threshold value of each transmission path, so that a large capacity multimedia stream can be transmitted quickly and seamlessly. A method and system for optimal path bowing in

According to the present invention, an optimal transmission path is always waiting for transmitting a multimedia stream, thereby enabling faster and more stable transmission. In addition, when there is an error in receiving the video stream, by setting the fastest transmission path among the plurality of audio reception paths as the video reception path, the video stream can be continuously received without delay or interruption at all times. The transmission path can be leveled up or down and level shifted according to the delay value of.

Multicasting, optimal path, bowing, delay, level, router, relay, network

Description

Method and System for Voting Optimum Route in Multicasting             

1 is a conceptual diagram of a multicast network applying a conventional peer-to-peer transmission scheme;

2 is a schematic view showing the configuration of an optimal path bowing system according to an embodiment of the present invention;

3 is a configuration diagram schematically showing the internal configuration of the relay broker terminal 220,

4 is a configuration diagram schematically showing an internal configuration of a bowing relay broker terminal 230;

FIG. 5 is a flowchart illustrating a process of leveling down a transmission path between an upper parent terminal and a lower child terminal in an optimal path bowing method in multicasting according to an embodiment of the present invention.

6 is a flowchart illustrating a process of leveling up an abnormal transmission path between an upper parent terminal and a lower child terminal in a method for optimal path bowing in multicasting according to an embodiment of the present invention;

FIG. 7 is a flowchart illustrating a process of level shifting due to an abnormal transmission path between an upper parent terminal and a lower child terminal in a method for optimal path bowing in multicasting according to an embodiment of the present invention.

※ Explanation of codes for main parts of drawing

105: data source 107: data transmission server

109: router 1 110: data source side network

120: Internet 130: client side network

132: Router 2 134 ~ 138: Client

200: optimal path bowing system 210: main server

220-228: relay broker terminal

230-238: bowing-relay broker terminal

240 248: botting terminal 310: connection information management unit

320: data transmission and reception control unit 330: media channel management unit

340: lower list management unit 350: data transmission unit

410: data receiving unit 420: upper list management unit

The present invention relates to the field of multicasting technology in an internet broadcasting system, and more particularly, when an abnormality such as delay or interruption of a video stream occurs while receiving multimedia data of a predetermined size or more multicasted from a main server in the form of a stream. For example, the audio transmission path having the fastest transmission speed among the plurality of audio transmission paths may be set as a video transmission path, and the transmission path may be set through level up, level down, and level shift according to the delay value and the threshold value of each transmission path. By setting up, the present invention relates to a method and system for optimal path bowing in multicasting to enable a fast and seamless transmission of a large multimedia stream.

As it is very difficult to modify the configuration of the router in the Internet transmission, recently, a client receiving data from the sender as unicast without uploading the router at all uploads the received data. By relaying, a multicast scheme has been developed that allows other clients to receive data.

1 is a conceptual diagram of a multicast network using a conventional peer-to-peer transmission scheme.

As shown in FIG. 1, the multicast scheme allows uploading data received from the data transmission server 107 of the network 110 where the data source 105 is located to the network 130 to which the client 134 belongs. The other clients 136 and 138 of the network 130 will then receive data from the client 134. That is, when the relay client in the network receives the data, the relay client performs a function as a repeater so that the relayed client can deliver the received data to other clients in the same network. At this time, the relay client is provided with a relay function execution program, and the multimedia stream is transmitted to another client by the relay function execution program.

Meanwhile, in order to receive a large amount of data, another client receiving a multimedia stream through the relay client should select a relay client having the fastest transmission path. Common methods of finding the fastest transmission path include the "Nearest" method, which passes the least number of routers, and the "Fastest" method, which checks the response speed while transmitting the "Ack" signal through communication and finds the path that responds the fastest.

In the case of the "Nearest" method, the data is streamed by setting the transmission path by adopting the least number of router paths transmitted from the media server. In this case, if the number of routers is reduced to reduce the load and the router speed is fast, smooth streaming by fast data transmission is provided. However, since the speed of streaming according to data transmission is not absolutely proportional to the number of hops (hops), the route is selected by selecting four routers that are faster than passing through three routers that are degraded. And transferring data may be effective.

In the "Fastest" method, only the routers with the fastest response speed among the routers transmitted from the media server are selected, and only the routers are routed to transmit data and stream the data. In this case, there is an advantage that the data transmission rate is much more reliable and faster than that of the "Nearest" method.

However, the "Fastest" method is not absolute either, because the response speed alone is not suitable for transmitting a large amount of data. In other words, because the response speed of a small bandwidth is fast, as the size of a transmission varies according to the size of the bandwidth, it is not considered that a large amount of data is transmitted than a large bandwidth. Also, because the speed of the network is constantly changing, this path is not absolute.

In order to solve the above problems, the present invention is directed to a plurality of audio transmission paths when an abnormality such as delay or interruption of a video stream occurs while receiving multimedia data multicasted from a main server in a stream form. Set the fastest audio transmission path as the video transmission path, and set the transmission path through level up, level down, and level shift according to the delay value and the threshold value of each transmission path. It is an object of the present invention to provide a method and system for optimal path bowing in multicasting to enable fast transmission.

In order to achieve the above object, the present invention provides an optimal path bowing system for routing a path for receiving the most multimedia streams that are multicasted from the main server most quickly and stably. A plurality of delivery terminals that receive and relay to lower-level terminals; An optimal path bowing program is installed, and receives a video stream from the delivery terminal directly connected to itself, receives an audio stream from the other delivery terminal, and if there is an error in the receiving path of the video stream, each audio A plurality of broker terminals configured to compare the reception volume and the transmission speed with respect to the transmission path, set the newest video transmission path by bowing the fastest transmission path, and relay the received multimedia stream to a lower level terminal; The optimal path bowing program is installed, and receives the multimedia stream from the broker terminal, receives the video stream from the broker terminal directly connected thereto, and receives the audio stream from the other broker terminals. And a bowing terminal receiving the video stream by bowing the audio transmission path having the fastest transmission among a plurality of audio transmission paths and setting the video transmission path when there is an error in the transmission path of the video stream. An optimal path bowing system for multicasting is provided.

According to another object of the present invention, a broker terminal for receiving a multimedia stream from a main server through a delivery terminal and relaying to lower level terminals, and a bowing for receiving the multimedia stream relayed from the broker terminal. An optimal path bowing method for a system including a terminal, comprising: a first step of receiving the multimedia stream including video and audio from a main server through a transmission path; A second step of comparing the reception amount and the speed for each audio transmission path and storing the transmission path upper list and the transmission path lower list; A third step of determining whether an abnormality including a delay or a truncation occurs in the reception of the video stream; A fourth step of determining whether the average delay value exceeds a threshold setting value through the delay values of the respective audio transmission paths to determine whether there is an error in one transmission path or an error in the overall transmission path; And a fifth step of comparing the reception amount and the transmission rate among the respective audio transmission paths and bowing the fastest transmission path to set the reception path of the video stream. to provide.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings.

In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

First, in order to help understanding according to the present invention, the basic concept of the present invention and the term 'voting' described in the embodiments will be described.

In the present invention, a plurality of terminals that initially receive the multimedia stream transmitted from the main server (Dispatcher: Cast 365 Plus Server) and relay it to a lower level terminal are called first level parent terminals, and are first level parent terminals. A terminal receiving a multimedia stream through the terminal is called a two-level child terminal.

In addition, when the 2nd level child terminal receives the multimedia stream from the 1st level parent terminal and relays it to the lower level 3rd level terminal, the 2nd level child terminal becomes a 2nd level parent terminal, and through the 2nd level parent terminal The terminal receiving the multimedia stream becomes a three-level child terminal.

Here, the first level parent terminal receives the multimedia stream through the optimal path from the main server and transmits the multimedia stream to the lower level 2 terminal, or the lower level 3 child by receiving the multimedia stream through the bowing path from the first level parent terminal. A two-level parent terminal or the like for relaying to a terminal is referred to as a "broker terminal" in the sense of receiving a multimedia stream and relaying it to a lower level terminal.

Meanwhile, the present invention basically provides about 10 second audio data of the second largest capacity among data constituting a transport stream composed of video and audio data in a tree-based multimedia transmission relay system. By constantly receiving data from the relay candidates and updating its status, the list is maintained to always find the best relay candidate. Here, the number of candidates can be arbitrarily adjusted in the configuration file.

In this case, when the connection delay or disconnection of the received video stream is performed, a superior value having the highest value is obtained by comparing 'receive amount' and 'transmission rate' among a plurality of candidate relay lists being received as existing audio data packets. Determining the audio path as the video transmission path is called 'voting'.

Therefore, the broker terminal of one level receives the multimedia stream from the main server (Dispatcher) unilaterally and relays it to the broker terminals of the lower two levels, which is called a "relay broker terminal" because it is a terminal that emphasizes a relay function.

In addition, the second level broker terminal receives the multimedia stream in the fastest transmission path through the bowing process from the upper level 1 parent terminal, and also relays the transmission to the lower level 3 child terminals according to the relay function. It is called a "bowing-relay broker terminal" which also functions as a relay.

The three-level broker terminal is called a "bowing broker terminal" that emphasizes the bowing function, because the terminal terminal of the final level does not have a relay function but only receives the multimedia stream through the bowing path.

As described above, when the terminal receives a multimedia stream from a higher level broker terminal, the terminal becomes a child terminal. When the terminal receives the multimedia stream to a lower level broker terminal, the parent terminal of that level The same applies to an N level transmission path.

Hereinafter, an embodiment of the present invention will be described using three levels of transmission paths as an example, but the present invention can be equally applicable to transmission levels of N level levels.

2 is a schematic view showing the configuration of an optimal path bowing system 200 in multicasting according to an embodiment of the present invention.

Optimal route bowing system 200 according to an embodiment of the present invention, the main server (Dispatcher) 210, relay broker terminal (220 to 228), bowing-relay broker terminal (230 to 238), bow And configured brokering terminals 240 to 248 and the like.

The main server 210 is a 'Cast 365 Plus Server' and multicasts broadcasting multimedia data including video, video, and audio in a stream form.

The relay broker terminals 220 to 228 first receive the multicasted multimedia stream from the main server 210 and perform tunneling to the client terminals or lower level broker terminals connected to the network through a multicasting router. do. That is, the terminal emphasizing the relay function in the broker terminal of the multimedia transmission.

The optimal route bowing program is installed in the bowing-relay broker terminals 230 to 238, and receives a video stream from the relay broker terminal 220 directly connected to itself, and the remaining relay broker terminals 222 to 228. Receives an audio stream from the audio stream, but if there is an error in the transmission path of the video stream, the video stream is received by setting the fastest audio transmission path as the video transmission path through the above-described bowing process, and the relay broker terminal. It relays the multimedia stream received from the lower level boating broker terminals 240 to 248.

The bowing broker terminals 240 to 248 are equipped with an optimal path bowing program, and receive the multimedia stream from the bowing relay broker terminals 230 to 238 through a multicasting router, but are directly connected to the bowing. In the case where the video stream is received from the relay broker terminal 230, the audio stream is received from the remaining bowing relay broker terminals 232 to 238, and there is an abnormality or an error in the transmission path of the video stream. Through the bowing process, the video transmission path is received by setting the fastest audio transmission path among a plurality of audio transmission paths.

The main server 210 is provided with a multicasting relay program, and the main server 210 downloads a relay function performing program for communicating between the multicasting relay program and each client terminal to each client terminal. The relay broker terminals 230 to 238 and the bowling broker terminals 240 to 248 are provided with a relay function execution program downloaded from the main server 210.

The relay function performing program receives the multimedia stream provided from the main server 210 by communicating one-to-one with the multicasting relay program mounted in the main server 210 via a plurality of multicasting routers.

3 is a configuration diagram schematically showing an internal configuration of the relay broker terminal 220.

As shown in FIG. 3, the relay broker terminal 220 is configured to transmit target level information and a speed information value of a current connection to transmit a multimedia stream. Data transmission / reception control unit 320 for processing various messages required, processing for latency, and controlling the dynamic routing (processing when reaching maxAccumLatency), a corresponding channel ( A media channel manager 330 for managing connections for each sub stream, a lower list manager 340 for storing route list information for transmitting the multimedia stream to lower-level terminals, and transmitting the multimedia stream to the outside; It has a configuration including a data transmitter 350 and the like.

In this case, the data transmitter 350 checks the connection state with the lower level child terminal so as to perform dynamic routing.

4 is a configuration diagram schematically showing an internal configuration of the bowing-relay broker terminal 230.

The bowing-relay broker terminal 230 of FIG. 4 includes a data receiver 410 for receiving a multimedia stream transmitted from the relay broker terminal 220 in the same internal component as the relay broker terminal 220; And further comprising a senior list manager 420 storing transmission path list information for receiving a multimedia stream from higher level terminals.

Here, the lower list manager 340 and the upper list manager 420 store a plurality of audio transmission paths in addition to the video transmission paths. The lower list manager 340 and the upper list manager 420 compare the transmission speeds of the audio streams obtained as in Equation 1 below. List information is sorted and stored.

Therefore, the lower list manager 340 and the upper list manager 420 compare the speed with the existing linked list and sort the speed in descending order to update the list when a new connection is made.

When a connection delay or disconnection occurs while receiving the multimedia stream, the data receiver 410 reads the highest value, that is, the fastest value, from the current list of the upper list manager 420 and sets the transmission path. In addition, for the transmission path set as the connection path, the rate value is lowered to 1/2 to update the candidate list.

Next, an operation of the optimal path bowing system 200 according to the embodiment of the present invention configured as described above will be described.

In an embodiment of the present invention, the latency represents a delay for the transmission of a packet between a parent terminal of one level and a child terminal of two levels. In addition, the reception delay value (Receive Latency) represents the difference between the time that the child terminal should receive the packet and the actual received time. In addition, the send delay value represents a difference between the time at which the packet should be transmitted and the time at which the packet is actually transmitted. The calculation delay value (Accumulate Latency) is an accumulation value of delay, and dynamic routing occurs when this value exceeds a set value.

Meanwhile, in the present invention, the senior list is a list of broker terminals transmitting a multimedia stream to the child terminal, and the lower list is a broker terminal receiving the multimedia stream from the parent terminal. List

Therefore, when the broker terminal level down from the child terminal point of view, the newly connected parent terminal requests a lower list from the parent terminal of the child terminal, and the new parent terminal newly connects the child terminal. Pass the sublist to. At this time, the child terminal becomes an upper list.

In addition, audio packets for upper and lower connections are transmitted over the stream connection, and the response is transmitted in order of one packet first.

FIG. 5 is a flowchart illustrating a process of leveling down a transmission path in an optimal path bowing method in multicasting according to an embodiment of the present invention.

First, the level down means that the path with the self occurs while the bowing-relay broker terminal 230 receives the multimedia stream from the relay broker terminal 220 of the upper parent level. Step down method.

The child level bowling-relay broker terminal 230 receives the multimedia stream from the main server 210 through the parent level relay broker 220, but the video stream is the first relay broker terminal 220. And the audio stream is received from the other relay broker terminals 222 to 228 (S502).

As the child terminal, the bowing-relay broker terminal 230 compares the transmission amount and the speed for each audio transmission path received in the sub-stream, and stores and manages it in the upper list manager 420 as the path list from the best path. (S504).

Thereafter, the bowling-relay broker terminal 230 determines whether there is an abnormality such as latency or disconnection while receiving the multimedia stream (S506).

If an error occurs while receiving the multimedia stream, the bowing- broker type broker terminal 230 obtains a delay value for each path for all other audio transmission paths, including the transmission path of the video stream, and then obtains an overall delay average value. (Average Latency) is obtained, the flag value (DownCount) is increased to determine whether the threshold setting value is exceeded, and it is determined whether or not there is an abnormality between the upper parent terminal and itself or the entire receiving path (S508). Here, it is recognized that the delay average value is not good overall when it is more than 1/2 of all transmission paths.

When it is determined that the abnormal level between the relay broker terminal 220 of the parent level and the child-level bowling-relay broker terminal 220 itself (S510), the child-level bowling-relay broker terminal 230 The lower level connection information of the fast transmission path is received from the relay broker terminal 220 of one level (S512). That is, when an abnormality occurs in the transmission to the lower child level, the relay broker terminal 220 of the first level reads the lower connection information from the lower list manager 340 and outputs the two-level relaying broker terminal 230. Provide).

Accordingly, the two-level child's bowling-relay broker terminal 230 terminates the connection with the one-level parent relay broker terminal 220 and has a three-level child-leveling broker terminal 242. (S514). That is, when the threshold value is exceeded by comparing the threshold value of the setting value, the level down of the transmission path setting occurs.

Subsequently, the bowing broker terminal 242 stores the lower connection information received from the relay broker terminal 220 as the upper connection information in the upper list manager 420, and the parent terminal of the second level based on the upper connection information. In step S516, a new connection is established with the bowing-relay broker terminal 232 of the fastest transmission path.

Accordingly, the bowing broker terminal 242 can safely receive the multimedia stream through the new bowing-relay broker terminal 232 of the fastest transmission path.

6 is a flowchart illustrating a process of leveling up a transmission path in an optimal path bowing method in multicasting according to an embodiment of the present invention.

First, in the level up, an abnormality such as a delay or a disconnection occurs in a path where the child level bowling broker terminal 240 receives the multimedia stream from the high parent level bowling-relay broker terminal 230, This is a method of leveling up the transmission path with the upper parent terminal when the above is 1/2 or more of the entire paths.

The child level bowling broker terminal 240 receives a multimedia stream from the main server 210 through the relay broker terminal 220 and the parent level bowling-relay broker terminal 230 (S602).

As the child terminal, the bowing broker terminal 240 compares the transmission amount and the speed for each audio transmission path received in the sub-stream, and stores and manages it in the upper list manager 420 as a path list from the best transmission path. (S604).

Thereafter, the bowling broker terminal 240 determines whether there is an abnormality such as latency or disconnection while receiving the multimedia stream (S606).

In case of an abnormality in the reception of the multimedia stream, the bowing broker terminal 240 obtains a delay value for each path with respect to all other audio transmission paths including the transmission path of the video stream, thereby obtaining an overall average latency. It is determined whether the threshold value is exceeded by increasing the flag value UpCount, and it is determined whether there is an abnormality between the upper parent terminal and itself or whether there is an abnormality in the entire reception path (S608). Here, when the delay average value is 1/2 or more of the entire transmission path, it is recognized that the connection situation of the overall reception path received through the parent-level bowing- broker type broker terminal 230 is not good.

If the flag value is increased and the threshold value is exceeded in comparison with the threshold setting value (S610), the child-level boating broker terminal 240 transmits quickly from the two-level parenting-relay broker terminal 230. The upper connection information of the path is received (S612). That is, when an abnormality occurs in the transmission to the lower child level, the two-level bowling-relay broker terminal 230 reads the upper connection information from the upper list management unit 420 and performs the three-level bowling broker terminal 240. )

Accordingly, the three-level child's bowling broker terminal 240 terminates the first bowling of the two-level parent-connection with the relay broker terminal 230 and the second-level second bowling, which is the parent level to itself. Switch to the relay broker terminal 232 (S614).

Subsequently, the new bowing-relay broker terminal 232 is the new relay type of the fastest transmission path among the 1-level relay broker terminals based on the senior connection information received from the previous relay broker terminal 220. A new connection is established with the broker terminal 222 (S616).

Thus, the lowest child level bowling broker terminal 240 is leveled up to the high parental level bowling-relay broker terminal 232 and has been the child level for the upper one level, the bowling-relay broker terminal. 230 determines dynamic relationship with the relay broker terminal 222 after determining the relationship with the upper parent level.

FIG. 7 is a flowchart illustrating a process of level shifting a transmission path in an optimal path bowing method in multicasting according to an embodiment of the present invention.

First, the level shift is an operation that occurs when the above level down or level up conditions do not correspond, and the child level bowling-relay broker terminal 230 is the first relay broker terminal 220 of the upper parent level. In this case, a delay or disconnection occurs in a path for receiving a multimedia stream, and the transmission path with the upper parent terminal is shifted. Therefore, the threshold of level shift is always smaller than the threshold of level up or level down.

The child level bowling-relay broker terminal 230 receives the multimedia stream from the main server 210 through the parent level relay broker 220, but the video stream is the first relay broker terminal 220. Received through, and receives the audio stream through the other relay broker terminal (222 ~ 228) (S702).

As the child terminal, the bowing-relay broker terminal 230 compares the transmission amount and the speed for each audio transmission path received in the sub-stream, and stores and manages it in the upper list manager 420 as a path list from the best transmission path. (S704).

Thereafter, the bowling-relay broker terminal 230 determines whether there is an abnormality such as latency or disconnection while receiving the multimedia stream (S706).

If an abnormality occurs while receiving the multimedia stream, the bowing- broker type broker terminal 230 obtains an average latency of the transmission path of the video stream, increases the flag value, and sets a level shift threshold. It is determined whether the value is exceeded (S708).

If it is determined that the flag value exceeds the level shift threshold setting value (S710), the child-level bowing- broker broker 230 terminates the connection with the one-level parent relay broker 220. In step S712, a new connection is established by selecting a transmission path having the fastest transmission path from the upper list of the upper list management unit 420.

Accordingly, when an abnormality occurs while receiving the multimedia stream, the bowing- broker type terminal 230 obtains a delay average value for the video path and increases the flag value to exceed the level shift threshold. By shifting a higher level parent terminal to establish a new connection, it is possible to continuously and continuously receive a multimedia stream.

In addition, when the reception path of the multimedia stream is in a network address translator (NAT) or firewall (Firewall) environment, the multimedia stream provided from the main server 210 is transmitted by TCP tunneling, and the main server 210 which is a central server. You can keep your connection with you. That is, since a broker terminal having a public IP cannot directly connect to a broker terminal in a NAT, first, when a request for reverse connection is made by transferring its connection information to the main server 210, the main server 210 is requested. ) Informs the broker terminal in NAT that there is a reverse connection request and delivers the connection information of the broker terminal that requested the reverse connection, and allows the broker terminal in the NAT to connect to the public IP broker terminal using the connection information. Will be.

Meanwhile, if one audio transmission path is switched to the video transmission path, the relay broker terminal or the bowling broker terminal adds one of the remaining spare paths to the audio transmission path to receive the audio data. Therefore, it is possible to receive a large amount of data of the multimedia stream faster by always waiting for the optimal repeater candidate.

As described above, according to the present invention, when an abnormality such as delay or interruption of a video stream occurs while receiving multimedia data of a predetermined size or more multicasted from the main server in the form of a stream, the transmission rate among the plurality of audio transmission paths is the highest. Sets the fastest audio transmission path as the video transmission path, but sets the transmission path through level up, level down, and level shift according to the delay threshold of each transmission path, so that a large amount of multimedia streams can be transmitted quickly and seamlessly. A method and system for optimal path bowing in multicasting can be realized.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, it is possible to transmit the multimedia stream more quickly and stably by always waiting for the optimum transmission path. In addition, when there is an error in receiving the video stream, by setting the fastest transmission path among the plurality of audio reception paths as the video reception path, the video stream can be continuously received without delay or interruption at all times.

In setting the fastest optimal path, the transmission path can be leveled up, down, and level shifted according to the delay value of each transmission path.

In addition, if there is a delay of data for a predetermined cumulative time in advance automatically prepared for a traffic situation that occurs frequently, there is an advantage that the continuity of data transmission is guaranteed to the maximum by switching to the next optimal path among the candidate candidates.

Claims (16)

In the optimal path bowing system for bowing the path that receives the multimedia stream that is multicasted from the main server fastest and reliably, A relay broker terminal which first receives the multimedia stream multicasted from the main server and relays the multimedia stream to lower level terminals; Receive a video stream from the relay broker terminal directly connected to itself, and receives the audio stream from the other relay broker terminal, if there is an error in the receiving path of the video stream and the amount of reception for each audio transmission path A bowing-relay broker terminal configured to compare the transmission speeds, bow the fastest transmission path, set a new video transmission path, and relay the received multimedia stream to a lower level terminal; Receive the multimedia stream from the bowing-relay broker terminal, receive the video stream from the bowing-relay broker terminal directly connected to it, and the audio stream from the other bowing-relay broker terminals. And a bowing broker terminal receiving the video stream by bowing the audio transmission path which is the fastest among a plurality of audio transmission paths and setting the video transmission path when there is an error in the transmission path of the video stream. Optimal path bowing system for multicasting comprising a. The method of claim 1, The relay broker terminal may include: a connection information manager configured to store target level information and a speed information value of a current connection to transmit the multimedia stream; A data transmission / reception control unit for processing various messages required for data transmission, processing a delay value, and controlling a dynamic routing; A media channel manager managing a connection for each channel (Sub Stream); A lower list manager which stores route list information for transmitting the multimedia stream to lower-level terminals; And a data transmitter for transmitting the multimedia stream to the outside. The method of claim 1, The bowling-relay broker terminal may include: a data receiver configured to receive the multimedia stream transmitted from the relay terminal; A senior list manager configured to store transmission path list information for receiving the multimedia stream from upper level terminals; A connection information manager configured to store target level information and a speed information value of a current connection to transmit the multimedia stream; A data transmission / reception control unit for processing various messages required for data transmission, processing a delay value, and controlling a dynamic routing; A media channel manager managing a connection for each channel (Sub Stream); A lower list manager which stores route list information for transmitting the multimedia stream to lower-level terminals; And a data transmitter for transmitting the multimedia stream to the outside. The method of claim 1, The audio speed of the audio transmission path is obtained by the total number of packet size * 256 / (current time-packet transmission time) / sub-level (Child). The method of claim 1, Optimal route bowing system for multicasting, characterized in that an optimal route bowing program is installed in the relay broker terminal, the bowing-relay broker terminal and the bowing broker terminal. The method of claim 3, wherein And the lower list manager and the upper list manager update the list by comparing speeds in descending order by comparing speeds with existing linked lists when establishing a new connection. The method of claim 3, wherein If a connection delay or disconnection occurs while receiving the multimedia stream, the data receiver reads the highest value of the fastest value from the current list of the upper list manager and sets the transmission path, and sets the transmission path. An optimal path bowing system for multicasting, wherein the path value is reduced to 1/2 to update the candidate list. The method of claim 6, When the reception path of the multimedia stream is in a network address translator (NAT) or firewall environment, the multimedia stream provided by the main server is transmitted by TCP tunneling and continues to connect with the main server as a central server. Optimal path bowing system in multicasting, characterized in that it is maintained. Receiving the multimedia stream through the relay broker terminal from the main server and relayed to the lower-level terminals, and receiving the multimedia stream relayed from the bowling-relay broker terminal In the optimal path bowing method of a system including a bowing terminal, A first step of receiving the multimedia stream including video and audio from the main server through a transmission path; A second step of storing the transmission paths as an upper list and a lower list by comparing a reception amount and a speed for each audio transmission path; A third step of determining whether an abnormality including a delay or a truncation occurs in the reception of the video stream; Obtaining a delay average value of the video transmission path and increasing a flag value to determine whether a threshold setting value is exceeded; And And when the flag value exceeds the threshold setting value, comparing the received amount with the transmission rate among the respective audio transmission paths, bowing the fastest transmission path and setting it as a reception path of the video stream. Optimal Path Bowing Method in Multicasting. The method of claim 9, As a result of the determination in the fourth step, when there is an error in one transmission path between the bowling-relay broker terminal and the relay terminal based on the bowing-relay broker terminal, the bowing-relay broker The terminal receives the lower connection information of the fast transmission path from the relay terminal, terminates the connection with the relay terminal, switches to the bowing terminal at a lower level, and sets the lower connection information as upper connection information. Optimal route bowing in multicasting characterized by performing a level down of the transmission path by establishing a new connection with another bowing-relay broker terminal of the fastest transmission path based on the upper connection information. Way. The method of claim 9, As a result of the determination of the fourth step, when the bowing broker terminal receives the multimedia stream through the bowing-relay broker terminal, an overall transmission path between the bowing broker terminal and the bowing-relay broker terminal If there is an error, the bowing broker terminal receives higher connection information from the bowing-relay broker terminal and terminates the connection with the bowing-relay broker terminal based on the higher connection information. Switching to a bowing-relay broker terminal and establishing a new connection with another relay broker terminal of the fastest transmission path, thereby performing a level up of the transmission path. How to bow. The method of claim 9, As a result of the determination in the fourth step, there is an error in the transmission path between the bowling-relay broker terminal and the relay broker terminal based on the bowing-relay broker terminal, but there is an error in one transmission path. If there is no abnormality in the overall transmission path, the connection with the relay broker terminal is terminated, and the transmission path having the fastest transmission path is selected from the upper list of the upper list manager so that the other relay broker terminal may be newly connected. Optimal path bowing method in multicasting, characterized by performing level shift of a transmission path by establishing a connection. The method of claim 9, The audio rate of the audio transmission path is obtained by the total number of packet size * 256 / (current time-packet transmission time) / sub-level (Child). The method of claim 9, When the reception path of the multimedia stream is in a network address translator (NAT) or firewall environment, the multimedia stream provided by the main server is transmitted by TCP tunneling and continues to connect with the main server as a central server. Optimal path bowing method in multicasting, characterized in that it is maintained. The method of claim 9, The method for optimal path voting in multicasting, wherein the transmission path list is updated by reducing the speed value to 1/2 for the transmission path set as the connection path. The method of claim 9, The relay broker terminal, the bowling-relay broker terminal and the bowling broker terminal are one-to-one with a multicasting relay program mounted in the main server via a plurality of multicasting routers according to a relay function execution program. And receiving the multimedia stream provided from the main server by communicating with the main server.

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