KR20080055202A - System for transfering a large-sized digital content to multi-point using ip-multicast and method thereof - Google Patents

Abstract

A high-capacity digital content multipoint transmission system using IP(Internet Protocol) multicast and a method therefor are provided to prevent retransmission as possible through processing functions such as file partitioning, shuffling, and FEC(Forward Error Correction) in case of high-capacity digital content transmission, thereby improving transmission efficiency. Contents are partitioned on the basis of an MFTP(Multicast File Transfer Protocol) of an IETF(Internet Engineering Task Force), and an FEC is applied to the divided contents, then shuffling of an MFTP block is performed to send the contents(S101-S106). Order recovery and the FEC are carried out within the MFTP block of the received contents, and the partitioned contents are combined together(S107-S110).

Description

System for multi-capacity digital content multipoint transmission using IP multicast and its method {SYSTEM FOR TRANSFERING A LARGE-SIZED DIGITAL CONTENT TO MULTI-POINT USING IP-MULTICAST AND METHOD THEREOF}

1 is a system diagram for multi-point digital content transmission in large capacity according to an embodiment of the present invention.

2 is a flowchart specifically illustrating a transmission processing method of a digital content transmission server of FIG. 1.

FIG. 3 is a flowchart specifically illustrating a receiving processing method of the digital content receiving server of FIG. 1. FIG.

<Description of Symbols for Main Parts of Drawings>

101: digital content transmission server 102: RP (Rendezvous Point)

103: public Internet network 104: general remote worker

105: premium Internet network 106, 109: PE router

107, 110, 113: network switch 112: inter-regional transmission equipment

108, 111, 114: Digital Content Receiving Server

The present invention relates to a large-capacity digital content multi-point transmission system and method using IP (internet protocol) multicast, and more particularly, file division, shuffling, omnidirectional error recovery, etc. It is a technology that improves transmission efficiency and guarantees time and stability by preventing retransmission as much as possible through processing of.

Conventionally, when the content is transmitted to n points by unicast of UDP (User Datagram Protocol) including transmission control protocol (TCP) or retransmission on the public Internet, the integrity of transmission is guaranteed, but compared to one point of transmission. There was a problem that takes n times.

Even in the case of IP multicast transmission to reduce the time of n times, since packet delivery is not guaranteed due to the characteristics of the network having the best effort property, partial or full retransmission is required depending on the network state. There was a problem that the time can not be measured, and in the worst case, it may take longer than the unicast transmission time.

Accordingly, the present invention to solve the above-mentioned problem is to prevent retransmission as much as possible through the process of file division, shuffling, omnidirectional error recovery, etc. in the MFTP transmission method when transmitting large-capacity digital content to improve the transmission efficiency and time and stability The purpose is to ensure

In order to achieve the above object, a multi-point digital content multi-point transmission method using IP multicast according to an embodiment of the present invention divides content based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF). And applying a forward error recovery (FEC) to the divided content, performing a shuffling of the MFTP blocks to transmit the content, and recovering the order in the MFTP block of the received content and the forward error. And a second process of combining the divided contents after performing the recovery.

In addition, the large-capacity digital content multi-point transmission system using IP multicast according to an embodiment of the present invention, the content is divided based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF), the divided content After applying the FEC to the forward error recovery (FEC), and for transmitting the content by performing the ordering of the MFTP block, and the partitioning after performing the forward recovery of the MFTP block and the forward error recovery of the received content And a receiving device for combining the content.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a system configuration diagram for multi-point digital content transmission in accordance with an embodiment of the present invention.

Content multi-point transmission system of the present invention is a digital content transmission server 101, RP (Rendezvous Point; 102), public Internet network 103, general remote worker 104, premium Internet network 105, PE router (Premium) Provider Edge Router (106, 109), network switch (107, 110, 113), digital content receiving server (108, 111, 114), and inter-regional transmission equipment (112).

The digital content transmission server 101 serves to transmit digital content to the reception servers 108 and 111. The digital content transmission server 101 is a public Internet network 103 for connection of a general remote worker 104 and a premium Internet network 105 for content transmission and control through the RP 102 which is a central router for sharing tree support. ).

Here, the premium Internet network 105 is a service provider and a CSPs (Content Service Provider) to provide a premium service by introducing a new hierarchy to the Internet model, when the introduction of the packet priority is applied to the QoS ( Quality of Service can be guaranteed. Therefore, when the premium Internet network 105 is used, since the packet delivery can be guaranteed in the backbone section where packet loss occurs most, the rate of retransmission according to an error can be greatly lowered. It can be applied to the Internet network, but can be more effective in the premium Internet network (105).

The connection from the premium internet network 105 to the digital content receiving servers 108 and 111 is made through the PE routers 106 and 019 and the network switches 107 and 110.

If the digital content receiving server 114 is too far away and cannot be directly accommodated from the PE router 109, the PE router (eg, a local router (WDM) device, such as a conventional WDM (Wavelength Division Multiplexing) device, may be configured). 110 and the network switch 113 is connected to ensure the economics.

Hereinafter, a mass digital content transmission procedure in the digital content transmission server 101 according to an embodiment of the present invention will be described in detail.

Content transmission according to the present invention is performed through the following modifications and preprocessing based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF), which enables multicasting transmission.

First, the digital content transmission server 101 applies Forward Error Correction (FEC) to content to be transmitted (S101). Through this, even if some packet loss or error occurs in the received content, the original can be recovered without re-receipt.

Accordingly, the digital content transmission server 101 divides the file to which the FEC is applied in step S101 (S102). In the worst case, the divided content can be retransmitted to only part of the divided file, thereby preventing the retransmission of the entire file. At this time, even if a part of the divided file is lost, it is preferable to determine the content FEC bit rate so that recovery is possible through the immediately applied FEC.

When the file division is completed through the above process, the digital content transmission server 101 controls the digital content reception servers 108 and 111 and joins the reception servers to the MFTP reception group so as to enable IP multicast (S103). ).

The digital content transmission server 101 applies the FEC in units of MFTP blocks to prevent retransmission due to the loss of the data transmission unit (DTU) that is adjusted to the size of the maximum transmission unit (MTU) prior to the start of transmission (S104). Here, the MFTP block refers to a group of MFTP data messages, and the client reports the reception status of the data message in units of blocks. In addition, the DTU is a data transmission unit and means a protocol message including data transmitted from a server to a client. For example, when the content "A" is divided into 10 files in step S102, the MFTP block is composed of several MFTP blocks for transmitting the divided files to the MFTP, and the DTU transmits one block with a predetermined transmission. It is a unit to transmit by dividing by unit.

Thereafter, the digital content transmission server 101 mixes the order inside the FEC-applied block in order to increase the resistance to the BURST ERROR (S105). Here, the multiple error is, for example, assuming that one block is transmitted to 100 DTUs, and the first to fifth DTUs are sequentially lost among the transmitted DTUs. In the case of errors occurring in contiguous areas, it is difficult to recover through FEC, so the order of blocks is shuffled to enable recovery from multiple errors.

In step S105, when the internal block mixing is completed, the DTU is transmitted (S106). At this time, it is preferable to transmit the DTU until one block is completed by dividing the block unit according to the MFTP standard.

Thereafter, when block transmission is completed, it is checked whether there is a retransmission request from the receiving side (S107), and if there is a request, the corresponding DTU is retransmitted (S108). It is checked whether the transmission is completed, that is, whether the corresponding split file is completed (S109).

If the transmission is not completed in step S109, the process moves to step S106 to repeat block-by-block transmission, and if it is completed, it is checked whether all the divided files are transmitted, that is, whether the entire content has been transmitted (S110).

Thereafter, if the transmission is not completed in step S110, the process moves to step S103 to transmit the next divided file, and if so, the transmission ends.

Hereinafter, referring to FIG. 3, a procedure for receiving a large amount of digital content in the digital content receiving server 108 or 111 according to an embodiment of the present invention will be described in detail.

Receiving a large amount of digital content of the present invention is performed through the following modifications and post-processing based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF) capable of multicasting transmission.

Accordingly, when the digital content receiving servers 108 and 111 are requested to receive the content, they participate in the receiving group of the MFTP of the transmitting server 101 (S201). The DTU is received to the receiving servers 108 and 111 participating in the receiving group according to the MFTP standard (S202).

As such, when the DTUs are received, the digital content receiving servers 108 and 111 check whether all DTUs for one block have been received, that is, whether one block has been received (S203).

At this time, if it is not completed, the process moves to step S202 and continues to receive the DTU even. On the other hand, when one block is received, the original order of the block is restored, and the DTU loss is recovered through the FEC of the block (S204).

Thereafter, the digital content receiving servers 108 and 111 confirm whether the recovery is successful through the FEC applied to the block (S205), and if the recovery fails, the digital content receiving server 108 requests a retransmission for the unreceived DTU to the digital content transmitting server 101. After receiving again (S206), the processes S204 and S205 are repeated.

On the other hand, if the recovery is successful through the process S205, check whether there is an unreceived DTU (S207), and if there is an unreceived DTU, the reception error count is reduced by the number of unreceived DTUs (S208). In this way, if the reception error count is reduced, even if packet loss occurs, an error threshold (error threshold) can be reached and the probability of being excluded from the reception group can be lowered.

Thereafter, it is checked whether all blocks of all divided files have been received, that is, whether reception of the divided files has been completed (S209), and as a result, if the reception of the divided files is not completed, the process moves to step S202 and continues DTU reception.

On the other hand, when the reception of the divided file is completed, it is checked whether all the divided files have been received, that is, whether the entire content has been received (S210). As a result, if the entire content has not been received, the process moves to step S201 to continue the reception.

Meanwhile, when the entire content reception is completed, the divided files are combined into one file (S211), and the combined files are FEC recovered (S212).

Thereafter, it is checked whether the content FEC recovery is successful (S213). If it fails, the unicast transmission request is received separately for one of the unreceived divided files, and then the process moves to step S211. On the other hand, if the FEC recovery is successful, the content reception is terminated.

In this way, the present invention changes the pre- and post-processing and error threshold calculation methods such as file splitting, shuffling, omnidirectional error recovery, etc. to the quality assurance multicast transmission and the MFTP transmission method using the premium Internet backbone. Efficiently transmit large amounts of digital content to multi-point receiving servers

As described above, the present invention has an effect of efficiently providing a seamless transmission within a short transmission time in transmitting a large amount of digital content that must be guaranteed time and stability to multiple points.

In addition, the preferred embodiment of the present invention for the purpose of illustration, those skilled in the art will be able to various modifications, changes, replacements and additions through the spirit and scope of the appended claims, such modifications and changes are the following claims Should be seen as belonging to.

Claims (9)

Content is divided based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF), and after forward error recovery (FEC) is applied to the divided content, the content is mixed by performing an ordering of MFTP blocks. A first process of transmitting; And And a second process of combining the divided contents after performing the order recovery within the MFTP block of the received content and the omnidirectional error recovery. The method of claim 1, wherein the first process comprises: Applying first forward error recovery to content to be transmitted and dividing the content; Connecting the receiving servers to the MFTP receiving group to enable IP multicast; A first to third process of applying forward error recovery on a block-by-block basis to the divided content and then mixing the internal order of the block units; And And a first to fourth process of transmitting a mixed block data transmission unit (DTU) to the receiving servers. The method of claim 2, wherein the first process comprises: 1-5 to check if there is a retransmission request from a receiver when the data transmission unit (DTU) transmission is completed; Retransmitting the corresponding data transmission unit (DTU) when the retransmission request is made, and checking whether the divided content transmission is completed when there is no retransmission request; And The method of claim 1, further comprising the steps 1-7 of checking whether the entire content transmission is completed when the divided content transmission is completed. The method of claim 2, wherein the second process comprises: Step 2-1 of receiving the data transmission unit (DTU) after joining the receiving server to the receiving group; Step 2-2 of receiving all the data transmission unit (DTU) to recover the order in the block and to perform omnidirectional error recovery; Checking whether the omnidirectional error recovery succeeds and checking whether there is an unreceived data transmission unit (DTU) if successful; A step 2-4 of reducing a reception error count by the number of unreceived data transmission units (DTUs) when the non-received data transmission units (DTUs) are present; and checking whether reception of the divided content is completed if not. ; A step 2-5 of checking whether the reception of the entire content is completed when the reception of the divided content is completed, and combining the divided content when the reception of the entire content is completed; And a second to sixth step of performing omnidirectional error recovery on the combined content. The method of claim 4, wherein the second process, Check whether the omnidirectional error recovery is successful, and if it fails, request and receive the unreceived divided file in a unicast manner, and repeat the steps 2-5 to 2-6 when the reception is completed. The multi-point digital content multi-point transmission method using IP multicast, characterized in that it further comprises steps 2-7. Content is divided based on the Multicast File Transfer Protocol (MFTP) of the Internet Engineering Task Force (IETF), and after forward error recovery (FEC) is applied to the divided content, the content is mixed by performing an ordering of MFTP blocks. A transmitting device for transmitting; And And a receiving device for combining the divided content after performing the order recovery within the MFTP block and the forward error recovery of the received content. The method of claim 6, wherein the transmitting device, Applying forward error recovery to the content to be transmitted, partitioning the content, joining the receiving servers to the MFTP receiving group to enable IP multicasting, and then performing forward error recovery on a block-by-block basis for the divided content. The multi-point digital content multi-point transmission system using IP multicast, characterized in that for applying, the internal order of the block unit, and transmits the block-specific data transmission unit (DTU) to the receiving server in a mixed order. The method of claim 6, wherein the receiving device, When receiving the data transmission unit (DTU) from the transmitting apparatus, in-block order recovery and omnidirectional error recovery are performed. If the omnidirectional error recovery succeeds, it is checked whether there is an unreceived data transmission unit (DTU). When the multi-point digital content transmission system using IP multicast, the reception error count is reduced by the number of unreceived data transmission units (DTUs), and if it is not present, the reception of the divided content is completed. . The method of claim 8, wherein the receiver, When the reception of the divided content is completed, it is checked whether the reception of the entire content has been completed, and when the reception of the entire content is completed, the divided content is combined, and whether the omnidirectional error recovery is successfully performed, and if it fails, the unreceived divided file The multi-point digital content multi-point transmission system using IP multicast, characterized in that for requesting and receiving transmission in a unicast manner.

Images