WO2002078263A1

WO2002078263A1 - Method and system for multicasing cycle transmission data in data network

Info

Publication number: WO2002078263A1
Application number: PCT/CN2002/000184
Authority: WO
Inventors: Hongbo Gu
Original assignee: Hongbo Gu
Priority date: 2001-03-22
Filing date: 2002-03-21
Publication date: 2002-10-03
Also published as: CN1312633A; CN1122390C

Abstract

Method and system for multicasting circular transmission data in data network, which including following steps : a. A server transmits a group of data to one or more segments with 'scale' which is stored in the memory ; b. Providing catalogue information for client machines ; c. Separately and circularly transmitting data which is need to be transmitted by network to respective multicasting packet ; d. The client machine randomly adds one or more multicasting packets for receiving data according to the received catalogue information, and register the origin point at the time of starting receiving according to the scale of data segment, then checking and connecting data. The system which used said method can relieve the load of servers and the backbone of network, moreover, it can download data momentary, immediately and reliably, and it can also use data as soon as possible, so that the user who used the client machine timely, conveniently and reliably feels like unicasting.

Description

Method and system for cyclically transmitting data by using multi-eye transmission in data network

The present invention relates to a method and system for data transmission in a data network, and in particular, to a method and system for sending and receiving data in a data network using a multicast transmission method. Background technique

The transmission method commonly used in current data networks is usually a monocular transmission method, as shown in FIG. 1, that is, one-to-one transmission of data between the server 100 and the client 201, and each client requests data from the server 100, The server 100 sends a corresponding data specifically to the client. For example, the current browsing of web pages or video on demand through the Internet. The operation process of this method is roughly that an unspecified client sends a request to the server based on the IP address on the Internet, and the server transmits the corresponding file to the client according to the request. On the computer, the browser program reads the file according to the agreed-upon language format, such as HTML, etc. This data transmission method is characterized in that when the data transmission amount is not large, the duration that each client occupies the server bandwidth is generally short, so When the server load is not heavy, the server responds to the data transmission request in a timely manner and sends it at any time. Due to one-to-one transmission, the communication bandwidth (rate) between the server and the client can be adjusted according to the situation of the two parties. There is an error packet retransmission mechanism. Errors and lost data packets can be retransmitted in time.

However, since the monocular transmission method must occupy the transmission bandwidth of the server and the backbone network in real time during the data transmission process, when a large number (tens of thousands, millions) of clients request data from the server in the same period of time, the server responds to these The client needs to send a large amount of the same data, which increases the load on the server and the network backbone; and the more the client requests, the larger the load. The server sends video service data according to the requests sent by each client to the server, so that the client can request the programs that they are interested in at any time. However, due to the large data volume of video on demand, in the existing technology, first, the server is insufficient. At present, the best video on demand server can provide video on demand services to a maximum of 1,000 customers. For programs such as CCTV Spring Festival Gala or News Hookup, under the monocular transmission technology, if video on demand services are provided, hundreds of thousands of units are required. To The upper server provides services; secondly, even if there is a high-speed large-capacity server, the data network anywhere cannot carry the burden of the data transmission.

Therefore, for the case where a large number of customers need to download the same data, a multi-mode transmission mode should be used. As shown in FIG. 2, when the server 110 sends data in a multi-mode transmission mode, all the clients 211 and 212 that have joined the multi-mode transmission group. Both, 213 can receive this data at the same time. With multi-eye transmission, the server sends only one copy of the data, so the server load is not heavy. Only one copy of data is transmitted in the network backbone, and the distribution is replicated and distributed in the branch part of the network, so the burden on the network backbone is greatly reduced.

For example, the Cisco I0S network protocol provides a solution based on Mulcica and Unicast technologies. Its Network Engineering Series: Cisco I0S Network Protocol Solution Volume 1 : IP »(CISCO IOS SOLUTIONS FOR NETWORK PROTOCOLS VOLUME I: IP, [US] Ci sco Syetems company, published by the Electronic Industry Press in February 1999) The following explanation is given on page 828:

Traditional IP protocol communication only allows one host to send packets to a single host (ie, monocular transmission), or to send packets to all hosts (ie, broadcast transmission). IP multicasting provides a third solution—allowing a host to send packets (ie, group transmissions) to a subset of all hosts. The hosts in a subset are called group members. Packets sent to group members are identified by a single multicast group address. Multicast packets are delivered to the group with the best reliability, similar to monocasting.

The multicast network environment consists of senders and receivers. Any host, whether it is a group member or not, can be a sender, but the receiver can only be a group member.

All recipients of the multicast group are assigned to the same multicast address, and the sender uses this address as the destination address to deliver the packet to all members of the group.

The group membership of a multicast group is dynamically changed, and the host can join or leave the group at any time. There is no limit to the number and location of members of the multicast group. The same host can be a member of more than one different multicast group at the same time.

The composition and activity of the different groups are different and change with time. A group can be active for a long time or for a very short time. The members of a group are constantly changing. Groups containing members may also be inactive. The Manual of Network Interconnection Technology (Network Engineering Series, published by the Electronic Industry Press in April 1998) also introduces the multicast transmission method: The single-multicast transmission routing protocol (SMRP) is a transport layer protocol. It provides routing for multi-media data streams on the AppleTalk network. It supports Apple Computer Quick Negotiation (QTC) technology. SMRP relies on protocol services below the network layer to provide connectionless optimal transmission for multicast datagrams. In particular, SMRP simplifies the transmission of data from a single source to multiple destinations.

At present, the term Multicast (Mul t icas t) protocol mainly refers to the transmission mode in which the TCP / IP protocol group allows a host to send packets (ie, group transmission) to a subset of all the hosts, but as described in the AppleTalk Other protocol families such as SMRP also have protocols with similar functions, such as the IPX / SPX protocol family; the Ethernet protocol ERTHERNET among the second layer protocols of the network; C should be mainly used for wireless transmission and satellite data transmission protocols. This protocol not only It can be grouped by its address, and it can be grouped by the carrier frequency. The monocular transmission function (point-to-point transmission) is a function that almost all protocol families already have.

However, the current multicast transmission methods have the following disadvantages:

First, the multicast transmission server sends data once, so that when the server starts to send data, all clients that need this data must know the start time of the server to send data in advance, and join the multicast transmission group in advance or at the same time. Only when you receive data from the beginning can you receive a complete data. If one or more clients fail to join this multicast group in time, they will not receive complete data. Like the video-on-demand system mentioned above, due to the requirement to download and use data in a timely manner, the current multicast transmission methods cannot meet the requirements.

Secondly, the bandwidth used by the server to send data cannot be adjusted for the bandwidth owned by each client. However, if the existing multi-purpose transmission technology is used, the bandwidth used by all clients to receive data must be greater than or equal to the bandwidth sent by the server. Otherwise, the client cannot completely receive the data sent by the server, and it is impossible for all clients in the data network to receive data with a bandwidth greater than or equal to the bandwidth sent by the server.

Again, the multicast server does not have a retransmission mechanism for error packets. In this way, when the client receives an incorrect data packet, it cannot request the server to retransmit the data packet, and it cannot guarantee the complete and correct transmission of data. Summary of the invention

An object of the present invention is to provide a method and a system for cyclically transmitting data by using a multi-eye transmission method based on network data transmission in accordance with the foregoing shortcomings of the prior art. You can set the scale for each piece of data, and send the piece of data to at least one multicast transmission group. Use the multicast transmission method to reduce the load on the server and the backbone network, and make the client join the multicast anytime. The transmission group starts to receive data, and can all receive the piece of data completely. The client can automatically choose to join multiple multi-eye transmission groups of the corresponding bandwidth according to its own bandwidth and other factors to start the reception of multiple pieces of data at the same time. The client is receiving When erroneous data is obtained, the start time of receiving the corresponding segment of data can be calculated according to the ruler to correct the error to ensure the complete and correct reception of the data.

A further object of the present invention is to provide a method and system for cyclically transmitting data by using a multi-eye transmission method, combined with a mono-eye transmission method to receive data at the beginning, and utilizing the characteristics of its real-time response to implement a video-on-demand system server The features of real-time response and large amount of repeated data transmission effectively complete online real-time viewing.

The technical solution of the present invention is as follows:

A method for circularly transmitting data in a data network by using a multicast transmission, wherein a server that sends data takes the following steps:

a. The server stores at least a piece of data with a "ruler" to be transmitted in its memory; b. The server provides a directory letter about the data to be transmitted in a single-shot or multi-shot transmission c. The data to be transmitted by the server Send to the corresponding multicast group through the network respectively; d. During the data transmission period, the server starts to transmit again from the beginning after each multicast group is transmitted, and so on; or when at least one client is receiving The data is transmitted cyclically when the data is not transmitted; otherwise, the loop is terminated, and the data is transmitted cyclically again when at least one client needs to receive the data again.

The method, wherein the step a further comprises:

al. The server divides a set of data to be sent into several data segments with a "ruler", and Stored in its memory and transmitted to the corresponding multicast group.

In the method, the server transmits at least one piece of data with a "ruler" to multiple multicast transmission groups, and the time when each multicast transmission loops to the starting point of the data is staggered with each other.

The method described above, wherein: when the server transmits a group of data fragments that are divided into a number of "scales", the server transmits the first data fragment or the first several data fragments of the group of data to multiple multicast transmission groups, And the time when the multicast transmission group transmitting the same data segment is cycled to the starting point of this segment of data is interleaved.

The method, wherein: during the multicast transmission of a certain piece of data, the server can respond to the request of the client to transmit a part or all of this piece of data to the client in a monocular transmission manner.

The method, wherein: the "scale of the data" uses the sequence number of the data packet as the scale of the scale.

The method, wherein: when a piece of data to be transmitted is divided into a plurality of small files, the "scale" of the data uses the plurality of small files as a scale scale.

The method, wherein: the "scale" of the data uses the number of bytes or digits from a certain data point to the beginning or the end of the data segment as a scale.

A method for receiving data in a data network by using a cyclic multicast transmission, wherein a client receiving the data takes the following steps:

a. Clients who need to receive a certain piece of data, obtain the directory information related to this set of data from the multicast transmission group or directly from the server;

b. According to the directory information, the client receives this piece of data from one or several multicast transmission groups that transmit this piece of data, and records the "receiving start point" from which it starts to receive; It transmits data;

c. When the data received by the client from a multicast transmission group or a single transmission reaches or exceeds a corresponding "receiving start point" of this segment of data, stop receiving data from the multicast transmission group or a single transmission;

d. If the "receiving start point" is not the starting point of this piece of data, connect the same piece of data received at the "receiving start point". In the method, when: the received multiple pieces of data are each data piece after a set of data is divided into several data pieces, the client receives multiple pieces of data at the same time, and connects adjacent data pieces as a whole for use.

The method, wherein: the client loops to the start time of this piece of data according to the data transmitted cyclically, and uses the start point or end point of this piece of data as the "receiving start point", so that it is not necessary after receiving this piece of data Connect it at the starting point of reception.

The method, wherein: the client receiving the data verifies the data that has been received, and if the data is found to be incorrect or missing, the error or missing data fragments are positioned using the "scale," and the scale is positioned, and According to the directory information, calculate the time when a multi-eye transmission group will cycle to this scale next time, and join this transmission group to receive data in time to correct or supplement some errors or missing data.

The method, wherein: the client receiving the data verifies the received data, and if the data is found to be wrong or missing, the wrong or missing data segment is positioned with its "scale", and then the server is requested to monocularly Send some of the data described as erroneous or missing.

A server system for implementing cyclic transmission of data by using multi-mesh transmission includes a memory, a central processor, and a network adapter, and the server is configured to send data, where:

a. The server stores at least a piece of data with a "ruler" to be transmitted in its memory; b. The server provides directory information about the data to be transmitted in a single-shot or multi-shot transmission manner;

c. The server transmits the data to be transmitted to the corresponding multicast group through the network respectively. d. During the data transmission period, the server retransmits from the beginning again after the transmission of each multicast group is completed. At least one client transmits data cyclically when receiving data, otherwise the loop is terminated, and data is transmitted again until at least one client needs to receive data again.

A client system that implements cyclic transmission of data using multi-mesh transmission includes a memory, a central processor, and a network adapter, and the client system is configured to receive data, where:

a. The client that needs to receive a certain piece of data obtains the directory information related to this set of data from the multicast transmission group or directly from the server;

b. According to the directory information, the client transmits the multicast data group from one or several groups. Receive this piece of data and record the "receiving start point" of receiving it; or at the same time require the server to send data to it in a single transmission;

C. When the client receives data from a multicast transmission group or a single transmission, the client stops receiving data from the multicast transmission group or a single transmission when the data reaches or exceeds a corresponding "reception start point" of the data;

d. If the "receiving start point" is not the starting point of this section of data, connect the same piece of data received at the "receiving start point".

In the client system, when the received multiple pieces of data are each data piece after a set of data is divided into several data pieces, the client system receives at least one piece of data at the same time and connects adjacent data pieces, Or it can be used as a whole.

The client system, wherein the client system loops to the start time of the data according to the data transmitted cyclically, and uses the start or end point of the data as the "receiving start point" to complete the reception of the data. It is not necessary to connect the data at the starting point after receiving the data. Compared with the conventional monocular transmission method for browsing webpages, using the present invention greatly reduces the load on the server and the network backbone, and also makes it difficult for a hacker to attack the server, because the client only enters a certain multicast transmission group. And get a copy of the data, its request does not necessarily need to be sent to the server, all servers can be more strict management of its entrance.

The method and system for cyclically transmitting data in a data network by using multi-eye transmission, and utilizing the characteristics of the multi-eye transmission method itself to reduce the load on the network backbone, and by dividing the data to be sent by the server, each segmented data is set The scale is fixed, and the server sends the data to at least one multicast transmission group cyclically. According to the scale, any client can choose any time to join a multicast transmission group, and the scale is used to determine whether the data is complete and correct. The client can The multicast transmission group corresponding to its bandwidth is automatically selected, and the error data can be calculated and added to the reception time according to the scale, thereby effectively achieving low-load and large-capacity data transmission of the network backbone and server.

The present invention provides a method and system for transmitting data in a cyclic manner using multi-eye transmission in a data network. In combination with the mono-eye transmission method, when receiving data at the beginning, it utilizes the characteristics of its real-time response, thereby realizing When data is transmitted, it can respond to the client's request quickly, as well as It enables a large amount of data to be transmitted to realize video on demand, and has little impact on the bandwidth of the network backbone and the server. Compared with the prior art, which simply uses the multi-eye transmission method to transmit data, the present invention can download data quickly and reliably; download the data at any time and in time; start using the data as early as possible; the client on the client side feels like using Monocular transmission is as timely, convenient and fast. Brief description of the drawings

The technical solution of the present invention and its beneficial effects will be apparent from the following detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

In the drawings,

FIG. 1 is a schematic diagram of a data flow when downloading data or video-on-demand by using a monocular transmission method in the prior art Internet, and the clients 201, 202, and 203 are shown downloading the same set of data from the server 100;

FIG. 2 is a schematic diagram of a data flow for downloading data or opening a video conference by using a multi-mode transmission method in the prior art Internet. The figure shows clients 211, 212, and 213 downloading the same group of data from a multi-mode transmission group, respectively;

FIG. 3 is a schematic diagram of a data flow of a method for transmitting data in a multicast network in a data network according to the present invention. The diagram shows clients 221, 222, and 223 downloading required data from different multicast delivery groups. The client The machine 221 also downloads data from the server in a monocular transmission mode at the same time;

FIG. 4A shows the nth and 11 + 1th cycles of a segment of data that the server cyclically sends to a certain multicast transmission group in the first preferred embodiment of the present invention;

FIG. 4B shows a way for a client to receive data from the data sent by the server shown in FIG. 4A: a complete cycle of the start receiving point from the beginning to the next cycle;

FIG. 4C shows another way for a client to receive data from the data sent by the server shown in FIG. 4A: from the beginning of receiving to the next cycle, after the start receiving point, continue to receive a piece of redundant data;

FIG. 4D is a schematic diagram of calculating and receiving correct data in a subsequent cycle after an error is found in the data received by the client shown in FIG. 4B or FIG. 4C;

FIG. 5 shows a method for transmitting data using a multi-drop transmission cycle in a data network of the present invention. Schematic diagram of receiving data cyclically when the client has a small bandwidth;

FIG. 6 is a schematic diagram of a method for transmitting data in a multicast network using a multicast transmission in the data network of the present invention. When a client has a large bandwidth, it simultaneously joins multiple multicast transmission groups to receive data;

FIG. 7 is a schematic diagram of a method for transmitting data by using multi-eye transmission in a data network according to the present invention. A client with a larger bandwidth simultaneously combines a single-eye transmission mode and multiple multi-eye transmission groups to receive data; FIG. 8 is In the method for cyclically transmitting data in a data network of the present invention by using multi-eye transmission, a client with a larger bandwidth receives a part of data of a group of data by using single-eye transmission, and simultaneously receives the remaining data by using multiple multi-eye transmission groups. Schematic diagram

9A and 9B are schematic diagrams of a method for transmitting data using multiple S transmission cycles in a data network according to the present invention. The server uses multiple multicast transmission groups (a)-(e) to transmit the same piece of data and the client receives the schematic diagram. 9A is a schematic diagram of the receiving method used by a client with a smaller bandwidth. The client only joins a multicast transmission group to receive it. Figure 9B is a receiving method that can be selected by a client with a larger bandwidth. It uses multiple multicast transmission groups at the same time. Receive different parts of the same piece of data;

FIG. 10 shows another preferred embodiment of a method for cyclically transmitting data using a multicast transmission in a data network of the present invention. It shows that a client with a larger bandwidth receives multiple sets of data using multiple multicast transmission groups. Schematic

FIGS. 11A and 11B show a method for transmitting data in a cyclic manner in a data network according to the present invention. When a server uses multiple multicast transmission groups and a single transmission to transmit the same piece of data at the same time, the client receives the data. Schematic diagram, where FIG. 11A is the receiving method adopted by the client with a smaller bandwidth, and the client only joins a multicast transmission group and receives the data in a single transmission. FIG. 11B is a method that the client with a higher bandwidth can choose , Using multiple multicast transmission groups and monocular transmission to receive different parts of the same piece of data at the same time;

FIG. 12 is a transmission schematic diagram of the server transmitting two sets of data of A and B in multiple multicast transmission groups in the present invention, where the data of group A is divided into five data segments, and the first segment of data of group A uses three multi-II The transmission group transmits and 'cycles to the start point in time alternately with each other, and transmits a part of the first segment to the client in a monocular transmission manner. The client receives the data using both monocular transmission and multicast transmission. When receiving data in a multicast transmission mode, it starts to cycle to the starting point according to the multicast transmission group. Receive. detailed description

Hereinafter, the present invention will be described in detail.

Explanation of the concepts involved in the present invention:

1. Multi-eye transmission

At present, the term Multicast (Mul ticas t) protocol mainly refers to the transmission mode of the TCP / IP protocol group that allows a host to send packets to a subset of all hosts (that is, group transmission), but it is similar to TCP / IP. Other protocol groups such as the AppleTalk protocol group also have protocols with similar functions, called "simple multicast routing protocol (SMRP)". In addition, other protocol groups can also develop the same or similar functions as Multicast (Mul ticas t), for example: IPX / SPX protocol group; CDMA mainly used for wireless transmission; Ethernet in the second layer protocol of the network Network protocol (ETHERNET) and so on. Almost all protocol groups already have the function of monocular transmission (point-to-point transmission).

Therefore, the “multi-eye transmission” in the present invention is not limited to the multi-eye transmission (Mul t icas t) and unicast transmission (Unicas t) protocols based on the TCP / IP protocol group. A data network with head and mono functions.

Each port of a multicast IP address can transmit different content, so in the present invention, each port of the same multicast IP address can also be regarded as a different multicast group, which is used to transmit different data.

Server

In the present invention, a server refers to: a device capable of responding to a client's request and transmitting its required data to the client through a data network, which may be a device physically, or a group of devices that are far apart but can cooperate with each other A device that completes the method, for example, may send directory information and each data segment of a set of data to different devices, respectively.

3. Client

In the present invention, a client refers to a device that requires data, can send a request to a server through a data network, and can receive data transmitted by the server through a network. The same device can be both a client and a server, such as a proxy server in a forwarding role. 4.A set of data

In the present invention, a group of data refers to one or more data blocks that must be used as a whole in most cases. They can be one file or multiple files (for example, a web page consists of multiple Files), which can be data stored in the form of files, or data stored in other forms. The client does not necessarily download all of a set of data, for example, an interactive movie, it needs to determine its plot to develop (download this piece of data), or develop (download that piece of data) according to the choice of the audience.

5.Data fragments

In the present invention, the data segment refers to a plurality of segments formed by dividing the foregoing group of data in order to facilitate the client to flexibly receive data.

6.A piece of data

In the present invention, a piece of data generally refers to the above-mentioned set of data and a piece of data. When referring to a piece of data, it may be a set of data or a piece of data.

7, ruler and data with ruler

Due to the particularity of the present invention, when a client joins a multicast transmission group and starts to receive a piece of data, it may start receiving from any part of the data. Therefore, the client needs a ruler to locate the starting point where it starts to receive data. The ruler is One of the best methods; In addition, if there is an error in the data received by the client, a ruler is also needed to determine the start and end positions of the error data.

The data scale can be set in the following ways, but is not limited to the ways listed below:

(1), adding data that functions as a ruler scale every certain byte in the data;

(2). Use the sequence number of the data packet (the sender must pack and transmit the data in sequence when the data needs to be transmitted in the network) as the scale;

(3) The data is divided into a series of small files, and each small file is a ruler scale;

(4) using the number of bytes or digits of a data point to the beginning or end of the data segment as its scale;

(5) The time of the transmission process can be used as its natural scale, but at this time, the server needs to transmit data at a steady rate;

(6) A synchronization signal such as "hear tbea t" can be used as a scale. (7) The data scale can also be set by combining the above several methods.

Directory information

In the present invention, the directory information refers to the information provided by the server to the client in order to enable the client to receive data quickly and conveniently. The information may include, but is not limited to, the following information or a part thereof:-Whether the group data is divided into multiple How many pieces of data are divided into two pieces of data in total; which piece of data can be transmitted using the monocular transmission method, its address and port; which piece of data can be transmitted using the multicast transmission method, and which multicast transmission group is used; Each piece of data is transmitted using several multicast transmission groups, which multicast transmission group is used; the length of a group of data or a data segment; the current transmission progress of a multicast transmission group; which multicast transmission group can be used Fastest cycle to the beginning of this data.

The server may not provide the complete directory information for the client to choose, but recommends the client to use one or several multicast transmission groups according to the situation of the data it sends, or use a combination of monocular transmission and multicast transmission.

Many methods can be used to reduce the amount of transmission of directory information, and the method of contracting directory information can be used. For example, the server transmits daily news syndicated programs relatively fixedly using a certain and several multicast transmission groups. In this way, the client only needs one time To obtain all or a relatively fixed part of the relevant directory information and store it in the memory for a long time, so that the client does not have to accept the directory information every time it requests this program, or only receives the relatively changed part each time Just fine.

The server and client can use some algorithm to reduce the amount of information in the directory information. For example, the address of the multicast group used by each segment of a group of data is an IP address or port number that increases or decreases in order.

It is also possible to distribute the directory information in a certain section or sections of data and gradually transmit it during the process of receiving data.

9. Receiving starting point

In the present invention, because a process in which a server sends data to a multicast group is not necessarily synchronized with each client that receives data, most cases are: When a client starts receiving data from a multicast group, the server It is in the process of transmitting this data, so the data received by the client when it starts receiving data is not the starting point of this data itself. So the client may need to record its "access "Receiving start point", for example: You can record a series of data received at the beginning of reception and then use data string comparison to confirm, or you can use the "rule" or "ruler plus offset" method to record the "receiving start point" , Or book a "receiving start point" according to the directory information and record it. As shown in Figure 4B, a client starts to receive data at time t1 and records the position of the starting point of reception. At time t2, the client receives these five pieces of data. At the end, but does not stop, continue to receive the previous part of the same piece of data sent immediately by the loop. At time t 3, the data received by the client loops to the receiving starting position again. In this way, the data received from t1 to t2 It is the latter part of the data. From t2 to t3, the front part of the data is received. The client connects the two parts at the starting point of the reception to complete the data. When the transmission group receives the same piece of data, the client can stop the multicast transmission from this multicast transmission group when it receives another "receiving start point" from another multicast transmission group. The group receives data, because the data after another "receive start point" has been received from another multicast group or even received. Of course, the client can also set the starting point of this piece of data as special The starting point. In this case, it is not necessary to record the "receiving starting point". As for the connection at the "receiving starting point", it is even more unnecessary.

10.Memory

15 In the present invention, the memory means all devices capable of storing or temporarily storing information, and it may be an opposite storage device or a part of other devices.

11.Join and receive data from the multicast group

Joining and receiving data from a multicast group in the present invention may be direct or indirect. The classic multicast transmission protocol completes the functions of data replication and distribution. It requires all

20 The client receiving the multicast group data changes its address to this group address to receive a copy of the data stream, but now there is a new multicast network device that does not require the client to change its address to Group address, this device still completes the function of copying and distributing data according to the needs of each client, but this device converts the original destination address to the address of each client that requires this data. Its advantage is that it does not support classic Adding such a device to a multicast network

25 to transfer data from one point to multiple destinations. This situation can be considered as the client indirectly joining and receiving data from the multicast group.

The present invention is divided into a server sending method and system and a client receiving method and system. These two methods and systems are implemented relatively independently step by step, but must be technically coordinated with each other. Just Like the transmitting equipment (corresponding to the server) and television (corresponding to the client) of a television station, a server can send a group of data or multiple groups of data at the same time, and a client can also receive one or more groups of data at the same time. However, in order to facilitate understanding, the following describes a combination of sending and receiving one or more sets of data.

The process for transmitting data in a data network by using multi-mode transmission is:

1. The data is processed into a format convenient for this method and stored in the server's memory: a. The server divides a group of data to be sent into multiple data fragments (this work can also be completed by other computers in advance, even in The process of producing data is completed together), and various segmentation forms can be used. It is not necessary to split for a smaller set of data.

b. You can add a "ruler" to each piece of data (this work can also be completed by other computers in advance, completed in the process of making data, or you do not add a "ruler" before storing it in internal or external memory (It is added before the server sends the data to the network.) You can also use natural rulers such as time.

c Store the processed data in the server's memory.

2. Each piece of data that the server will need to transmit can be an undivided group of data, or it can be the divided data fragments, which are transmitted to different multicast transmission groups respectively, so that the client can flexibly choose the same time. Receive one or more pieces of data. Figure 3 shows the data flow when the present invention uses three multicast transmission methods to download data or perform video on demand in the Internet network (the present invention is not limited to three multicast transmission groups, and any number of multicasts can be used according to the actual situation). Destination transmission group), and clients 221, 222, and 223 download the same set of data from the multicast transmission group, respectively. Both basic modes of the invention can be shown in the figures.

a. The server 120 cyclically transmits the same piece of data to three multicast transmission groups, and the time when each multicast transmission cycle reaches the starting point of this segment of data is interleaved. The client chooses to receive according to the actual situation.

b. The server 120 cyclically transmits a group of data divided into three data segments to three multi-eye transmission groups, and the client chooses to receive it according to the actual situation. Or it also allows the server to provide data to the client in a unicast mode, so that the client can use a more flexible receiving mode, or repair the data with errors in a unicast mode. 3. During the data transmission provided by the server, each data segment is transmitted again after the transmission is completed, and so on. The client that needs data can start receiving data fragments and complete a complete loop at any time, as shown in Figure 4A. Or, at least one client transmits data cyclically when receiving data, otherwise the loop is terminated, and the number of transmission groups transmits data cyclically until at least one client needs to receive data again.

4. If a client needs to obtain a group of data, it must first know whether this group of data is divided into multiple data fragments; it is divided into several data fragments; each segment is transmitted using several multi-eye transmission groups; Which multicast group is used to transmit each segment; and other related directory information. Therefore, it is required that the server be able to provide the directory information to the client in a unicast or multicast or other form.

5. Because the server transmits the data to be transmitted in a cyclic manner by using multi-purpose transmission, when the client needs to obtain the data, it can immediately join the corresponding multi-purpose transmission group, or wait for the cycle to the starting point of this segment of data. Add a multi-eye transmission group, or join the multi-eye transmission group at another appropriate time. For example, the client can receive and store the first part or the first or the first few clips of a certain type of program that the customer is interested in. The next part is only received when the program is actually on demand. If the "receiving start point" is not the starting point of this piece of data, the client records the "receiving start point" that starts to receive data at the same time, until it loops to a "receiving start point" of the client; Received or received by a multicast group. If the client uses the start or end point of this piece of data as the "reception start point", it is allowed not to make another record of this "reception start point". It is also possible to exceed the "Receive Start Point" for verification.

FIG. 4B shows how the client records the "receiving start point" in the present invention to cyclically receive data and correct errors. The client starts to receive data at tl time and records the "receiving start point". After receiving the end of this data, the client does not stop receiving until it loops to this "receiving start point" again. It can also exceed the "receiving start point". In order to verify the reception of the entire cyclic transmission data, as shown in FIG. 4C. The time point for looping again to the "reception start point" is t 3. If the client finds some errors (or missing) in the received data, it locates the data with errors (or missing), calculates the time to next cycle to this scale, and joins the transmission group to receive data in time To correct (or supplement) part of the data with errors (or missing), use the ruler to locate the "reception point" or errors, or "Ruler plus offset", or data string comparison, can also be used in other ways.

There is one point that needs special explanation. In order to facilitate understanding, the scale of the ruler is drawn under the bands that partially represent the transmitted data in Figs. 4A to 4D and Figs. 9A and 9B. Failure to draw the ruler ~ does not necessarily mean that the data does not have a ruler.

6. The client determines to receive data in a certain method or a certain combination according to its available network bandwidth, the processing capacity of the machine, and the actual needs. Several methods are exemplified below, but the invention is not limited to the following methods:

a. Only one segment is received at a time, and the complete segment data is gradually received; as shown in FIG. 5. The shaded part in Fig. 5 shows how a client with a smaller bandwidth in the present invention uses the positioning "receiving start point" to receive data in a loop. A group of data A is divided into five data segments Al ~ A5. The server transmits the five data segments to five multi-eye transmission groups in a cyclic manner. The client only joins one multi-eye transmission group at the same time, and gradually receives these five data. Data fragments. Of course, the client can also wait for the multicast group to join the multicast group when the cycle reaches the starting point, for example: receiving A1-2, A2-3, A3-4 in sequence, if the server sends the time of the starting point of each data segment cyclically Aligned with each other, the receiving effect will be better.

b. Receive several segments at the same time, and gradually receive the complete segment of data. At the same time, it can also receive certain segments of another set of data (requires larger bandwidth and strong processing capability) as shown in Figure 6. The shaded part in Fig. 6 shows how a client with a larger bandwidth in the present invention receives data in cycles using multiple multi-eye transmission groups. Among them, there are three groups of data people, B, C, and group A is divided into five data segments Al-A5, which are transmitted using multi-purpose transmission groups (a)-(e). Group B is divided into two data fragments Bl ~ B2, and transmitted using multi-eye transmission groups (f)-(g). Group C is divided into 4 data segments C1 ~ C4, and is transmitted using the multicast transmission group Oi)-(k). The server cyclically sends 11 data fragments to 11 multicast transmission groups. The client joins only a few (4 or 3) multicast transmission groups at the same time, and gradually receives all the data fragments described. Of course, the client can also wait for the multicast group to cycle to the starting point of this segment of data before joining the multicast group, for example: Receive A1- 2, A2-2, A3- 2, A4-2 in order.

A5-3, Bl_3, B2-3, CI-3, if the time of the starting point of the cyclic sending of each data segment is aligned with each other, the receiving effect will be better.

c. Receive all fragments at the same time, and also receive some fragments of another set of data, but A larger bandwidth and a stronger processing capability are required. As shown in the shaded part of FIG. 6, the client can receive two data segments of the B-group data in one cycle. Of course, the client can also wait for the multicast transmission group to join the multicast transmission group when it reaches the starting point of this segment of data.

d. Use a single transmission and a multiple transmission to receive each data segment of a group of data, as shown in Figure 7. The shaded part in Fig. 7 shows how a client with a larger bandwidth in the present invention uses a combination of unicast and multicast transmission groups to receive data cyclically. The client receives the first piece of data A1 by using the monocular transmission. Because the monocular transmission can be downloaded from the beginning of a piece of data, the client can use the data in time from the beginning of the data and receive it at the client. Within the time of using the data of the first data segment transmitted by the monogram, the client has received the data of the second, third, and fourth data segments A2 ~ A4 in the multi-eye transmission group (a)-(c) And stored in the client, while using the data of the second data segment, it can continue to receive subsequent data segments and several other sets of data. Of course, the client can also wait for the multicast group to cycle to the starting point of this segment of data and then join the multicast group, or receive A1 in the monocular transmission mode, and then receive other data fragments in the multicast transmission mode.

e. The use of monocular transmission and multi-eye transmission to receive a piece of data can be an independent piece of data or a piece of data of a group of data. The shaded part in Fig. 8 shows how a client with a large bandwidth in the present invention uses a unicast transmission and multiple multicast transmission groups to receive data cyclically. The monocular transmission is used to receive part of the data A1 of the first data segment of a group of data, and the multiple data transmission groups are used to receive the data segments A1-A4 at the same time. Because the monocular transmission can be downloaded from the beginning of a piece of data, the client can use the data from the beginning of the data in a timely manner. At the same time, the client receives the A2 ~ A4 data fragments at the same time by using the multi-eye transmission method, and records Start receiving

"Receiving start point", it can be seen from the figure that when the client starts to receive the first data segment A1 with the multi-cast transmission group (a), the server is in the process of transmitting this data, so when the client starts receiving data, In most cases this is not the starting point for this piece of data itself. So the client needs to record its

"Receiving Start". When the data received by the client through the monocular transmission reaches or exceeds this "receiving start point", it can stop receiving data through the monocular transmission, because the subsequent data has been received and stored to the client through the multicast transmission. Machine, and this can also save server bandwidth. This method can not only be used to receive a piece of data in a group of data, but also can be used to receive Receive a separate piece of data. In FIG. 8, A1 can be regarded as an independent piece of data. Of course, for a multicast transmission group other than the multicast transmission group (a), the client can wait for the multicast transmission group to cycle to the starting point of this segment of data before joining the multicast transmission group; or receive A1 in a single transmission first. Part of the data until the expected "receiving start point" that can be connected to the data of a multicast transmission group, and then start receiving another part of the data segment at the expected "receiving start point" in the manner of multicast transmission. f. Select receiving data from multiple multicast transmission groups transmitting the same piece of data, as shown in Figures 9A and 9B. 9A and 9B show that in the present invention, the server transmits a piece of data to a plurality of multicast transmission groups, and the time when each multicast transmission loops to the starting point of the data is staggered with each other.

In FIG. 9A, it can be seen that when the time is tl, the data transmitted by the multicast transmission group (a) is exactly cycled to the starting point of the data, and when the time is t2, the data transmitted by the multicast transmission group (b) is exactly Cycle to the starting point of this segment of data. When the time is t 3, the data transmitted by the multicast transmission group (c) is exactly cycled to the starting point of this segment of data. When the time is t4, the multicast transmission group (d) transmits. The data is looped to the start point of this segment of data. When the time is t5, the multicast transmission group (e) is transmitted to the start point of this segment of data. When the time is t6, the multicast transmission group (a) The transmitted data is cycled to the starting point of the data again. Therefore, the client chooses to receive data from the multicast transmission group (a) that can receive the starting point of this piece of data at the earliest. Of course, the client can also choose other multicast transmission groups. For example, some people do not like to watch the movie title, they can choose Multicast transmission group (e).

In the shaded part of FIG. 9B, it is seen that the client decides to receive data from the three multicast transmission groups at the same time according to the network bandwidth it has. Receive data. When the client receives data from the multicast transmission group (a) to the tl time point, the data is looped to the "reception start point" of the data received by the client from the multicast transmission group (e), so the client is after the tl time point It is then possible to stop receiving data from the multicast transmission group (a). When the client receives data from the multicast group (e) to the time point t2, the data is cycled to the "reception start point" of the data received by the client from the multicast group (c), so the client is after the time point t2 It is then possible to stop receiving data from the multicast group (e). When the client receives data from the multicast transmission group (c) to the time point t2, the data is cycled to the "receiving start point" of the data received by the client from the multicast transmission group (a), so it is possible after the time point t2 Stop receiving data from the multicast group (c). In this way, connecting these 3 parts of data is exactly A complete cycle is a complete piece of data. The reason why the multicast group (a) is selected is because the client can receive the starting point of this piece of data as early as possible. It can be seen from the figure that the multicast group (a) is cyclically transmitted to this piece of data at time t Q Starting point, if the client receives a video program, then the client can start watching the video on demand. Of course, the client can also wait for the multicast group (a) to join the multicast group when the multicast group circulates to the starting point of the data (t O), and it does not affect the timeliness of user viewing.

This method can be used not only to receive a piece of data as a whole, but also to receive one or more data fragments in a group of divided data, as shown in FIG. 10. FIG. 10 shows that in the present invention, the server sends the first piece of data A1 in more than three multicast transmission groups (a. B. C), and the client with a larger bandwidth receives data in multiple multicast transmission groups. It can be seen from the figure that the client receives a total of two sets of data A and ^ The server divides a set of data A into 5 data fragments A1 to A5, and divides a set of data B into 2 data fragments B1. B2, each data fragment Use separate multicast groups for transmission. The server transmits one of the data A, the first data segment A1 in three multicast transmission groups (a)-(c), and the time when each multicast transmission loops to the starting point of this data segment is interleaved It's open. Because the client has a large network bandwidth, the client can receive four data segments at the same time. When the client is ready to start receiving the first data segment A1 of the data, it can send packets from three multicast groups (a), (b), (c) Select one or more multicast transmission groups to receive data. In this figure, if the client uses the multicast group (a) to download the data, the data can be used from the time point; if the client uses the multicast group (b) to download the data, it can be used from the tl time point Data; if the client downloads the data using the multicast group (c), the data can be used from time t 3; if the client uses a suitable data stream, the data can be used from the beginning as soon as possible. In the figure, "a client" uses the multicast group (b) to start using the data as early as possible (at time t1). So the client selects the multicast group (b) to receive the first data segment. Receive the second, third, and fourth data segments at the same time. After that, a fifth data segment of a group of data A and two data segments of a group of data B are received. Of course, the client can also wait for the multicast group to join the multicast group when the cycle starts to the starting point of the data.

g. The above methods can be used in combination, for example, the two methods e and f are used in combination, as shown in FIG. 11A and FIG. 11B, which shows that in the present invention, the client uses multiple multicast transmission groups to receive the same A piece of data (the starting points are interleaved with each other) uses the monocular transmission method at the same time. It can be seen from FIG. 11A that the Yueliang server transmits one piece of data A with five multi-eye transmission groups, and the time when each multi-eye transmission loops to the starting point of this data segment is interlaced. The client receives the data using the monocast transmission method, and also uses one of the multicast transmission groups to receive the data and records the "reception start point". As can be seen from the figure, the client starts receiving the multicast transmission group (e). When a piece of data is transmitted, the server is in the process of transmitting this piece of data, so the data received by the client when it starts to receive the data (referred to as: "reception point") is not the starting point of the piece of data itself in most cases. So the client needs to use the "ruler" to record its "receiving start point". When the client receives data from the starting point of this piece of data in the monocular transmission mode and receives this "receiving start point", it can stop receiving data in the monocular transmission mode, because the subsequent data has been transmitted in the manner of multicast. Received and stored in the client, and this also saves server bandwidth. The client selects the multicast group (e) because using this multicast group can minimize the transmission volume of the monocular transmission, thereby saving the bandwidth of the server.

It can be seen from FIG. 11B and FIG. 11B that the server transmits one of the data A in five multi-eye transmission groups (a) to (e), and the time when each multi-eye transmission cycle reaches the start point of this data segment is Intertwined. The client receives data in a monocular transmission mode and also uses three of them to receive the data and record the "reception point". As can be seen from the figure, the client decides according to its own network bandwidth Receive data using the monocular transmission method, and simultaneously receive data from the three multi-eye transmission groups. Based on the directory information, it is decided to receive data from the multi-eye transmission groups (a), (c), and (e) first. When the client receives data from the start of this piece of data in a unicast transmission to the time t1, the "receiving start point" of the data received by the client and the data received by the client from the multicast transmission group (e) "Coincidence, the client can stop receiving data in a unicast mode after t1. When the client receives data from the multicast group (e) to the time point t2, the data is cycled to the "reception start point" of the data received by the client from the multicast group (c), so the client is at time t2 After that, you can stop receiving data from the multicast group (e). When the client receives data from the multicast transmission group (c) to the time point t2, the data is looped to the "receiving start point" of the data received by the client from the multicast transmission group (a), so it is possible after the time point t2 Stop receiving data from the multicast group (c). When the client receives data from the multicast transmission group (a) to the time t1, the data is cycled to the end of the data. Like this The connection of 4 parts of data is exactly a complete cycle, that is, a complete piece of data. In this way, by comprehensively using this method, clients with different network bandwidths can make full use of their bandwidth to receive data as quickly as possible, and meet other needs of customers. In the above example, the client mostly selects the receiving scheme based on receiving a group or a complete set of data in a timely manner as the main requirement. In practice, a more flexible selection scheme can be made according to the demand. For example, some people do not like watching movies or TV shows. At the beginning of the film, some people started to receive previously unfinished movies, etc. from the middle.

7. After receiving the data, the client performs validation on the received data. If the data is found to be wrong or missing, it can be corrected using the following methods:

a. Use the ruler of the data segment to locate the erroneous or missing data, and ask the server to resend one or more partial data with errors.

b. Locate and record erroneous or missing data. Immediately or at certain intervals, such as time, data volume, and number of segments, the server is required to resend part of the data with errors by means of monocular transmission.

c. Locate the erroneous or missing data and calculate the time when a multicast group will next cycle to this point and record it. Depending on the positioning of time or re-receiving some of the data with errors in advance, the relevant parts before and after can also be accepted as redundancy, as shown in Figure 4D. It is also possible to require the server to send part of the data with errors using the unicast transmission method.

8. The client can remove the "ruler" after receiving the correct data, merge multiple data fragments of the divided set of data, restore the original format of this set of data, or do not remove the "ruler" when storing. ", Does not do the physical operation of merging the fragments, but the client ignores the" ruler "when using these data, and connects the fragments, as long as the effect is the same as using the original continuous set of data, for example: Normal web pages are not connected when stored, but only used as a whole when they are read by the browser.

9. Considering the geographical bottleneck of the network or the country or administrative division, a proxy server can be set up in some places. The proxy server can either obtain data from the server or other proxy server using the receiving method or other methods in this method, or send data to the client using the transmitting method or other methods in this method.

In order to achieve the task of the present invention, the following innovative transmission methods are used comprehensively on the server side: (1) Multiple cyclic transmission of data The server transmits cyclically, and the client receives data from the multicast transmission group at any time. The server repeatedly sends a piece of data to certain multicast groups, and the starting times are staggered with each other. The client waits for the multicast transmission group to cyclically send to the start point of this piece of data to start receiving data, or can receive data from these multicast transmission groups at any time, as long as the client records the "reception start" record when it starts to receive data, The client can stop receiving data from this multicast group when it receives the "receiving start point" received from this multicast group again, or when the client receives from a multicast group You can stop receiving data from this multicast group when you reach another "receive origin" of another multicast group, because the data after the other "receive origin" is already expected to be received or even received from another multicast group pass. Because the client can choose a multicast group that is closest to the starting point of a piece of data, it solves the problem of real-time viewing of video on demand. Because the client can choose to join the number of multicast groups, it also solves the problem that different customers make full use of it. Problems with network bandwidth.

(2) Add a ruler to the data

Due to the particularity of the present invention, when a client joins a multicast transmission group and starts to receive a group or a piece of data, it does not necessarily start from the beginning of the data, so the client needs to be able to locate where it started to receive data. Starting point, using a ruler is one of the best ways to solve this problem.

In addition, if there is an error in the data received by the client, you also need to use a ruler to locate the position of the erroneous data in a piece of data in order to re-receive this part of the data.

(3) Segmentation of a group of data

If the server only uses the circular transmission method with a ruler to transmit data, the client can already receive data at any time, but this is not enough for some large data that requires real-time use. In addition, if All clients receive data from the same multicast group. This multicast group cannot take into account the network bandwidth of each client. Therefore, in the present invention, a group of data used as a whole can be divided into a plurality of data fragments and transmitted separately. In this way, the client can flexibly choose to receive data according to its actual situation. During the division, a repeated division transmission method may be adopted. For example, a group of data is divided into two data segments A and B, and the two multi-purpose transmission groups are transmitted respectively, and then the data segment A is divided into two data, Al and A2. The segments are respectively transmitted to two multicast transmission groups, and the entire group of data may also be transmitted to a certain multicast transmission group. Segmented data The content of the fragment is allowed to repeat each other. For example, the content of the previous part of A2 in the above example can be compared with

The contents of the latter part of A1 are repeated with each other.

In the present invention, data can be divided from multiple angles and in various ways. The following examples illustrate but are not limited to the following methods.

a. Divide according to the order of the data: For example, a group of 100M video data is divided into 10 segments according to the order of the data, each segment is 10M.

b. Segment by video data: For example, there is a set of video data, the resolution of each frame is 800 600. If we take the horizontal direction of this picture, one pixel is taken every other pixel, and the horizontal direction is taken every other line. Taking one method, this picture can be divided into four pictures with a resolution of 400 X 300 which are basically the same. In this way, a set of video data can be divided into 4 data segments. If one of the data segments is received and used, a video program with a resolution of 400 300 can be viewed, and if all four data segments are received and used in combination, a video program with a resolution of 800 600 can be viewed.

c Divide by the frame of video data: For example, there is a set of video data. Let's take the video composed of frame 1, frame 4, frame 7 as a data segment, and frame 2 and frame 5. Frame, 8th frame ... as a data segment, and 3rd frame, 6th frame, 9th frame ... as a data segment, if received separately And using one of the data segments, you can view a fast-forward video program at a rate three times the original video program. If you receive and use the three data segments together, you will see a video program playing at normal speed.

d. Split according to the left and right eye videos of the stereo video: Stereo video programs rely on the parallax of the left and right eyes to achieve the stereo effect. The left eye video and the right eye video are divided into two data segments. If one of the data is received and used separately Clips, you can watch general video programs. If you receive 2 data clips and use them in conjunction with corresponding equipment, you can watch stereo video programs.

e. Divide according to the content of the program: For example, take a picture of a program as a segment, background sound as a segment, character dialogues of different languages as optional segments, and subtitles of character dialogues of different different languages as optional segments. Clip, so the client can flexibly choose different language dubbing and subtitles.

f · Divide the data according to some mathematical algorithm. g. Use the above methods in combination: For example, you can use a, b, c, and d together. Customers who watch video programs can watch small-resolution, fast-forward, non-stereoscopic video programs first. Part of the conversion method, watching large-resolution, normal playback speed, three-dimensional video programs.

(4) Combined use of multi-eye transmission and single-eye transmission:

Using the unicast transmission mode, the server can respond to a client's request in real time and send data to the client from the starting point of a certain piece of data, or send a part or parts of data to the client as required. Therefore, the current video-on-demand systems use monocular transmission. The present invention utilizes this feature of the monocular transmission method, and transmits the data of the previous part by the monocular transmission method to meet the client's requirements for real-time performance. At the same time, the data of the latter part is transmitted by using the multi-eye transmission mode to reduce the load of the server and the network backbone. However, to successfully connect the two parts, it needs to be positioned in some way. For example, a data string comparison method may be used, that is, a part of the data at the "receiving start point" of the later part of the data is continuously compared with the newly received data, and if the data overlaps, the received data is determined to be

"Receive start point" coincides. You can also use the "ruler" to record the "receiving start point" of the data in the later part and connect it here. You can also use data segments to connect, that is, one or more of the previous data segments are transmitted by monocular transmission, and the subsequent data Clips are transmitted using a multi-drop transmission.

Industrial applicability

The following is a practical example to illustrate the application effect of the present invention in an actual environment.

In the following example, the server provides the transmission of a movie program or a news program, and the client needs to receive and watch the program. Of course, in actual applications, one server (or virtual server) can transmit multiple programs at the same time, and the client can also receive multiple programs at the same time or receive multiple programs in succession; it can also receive programs and other data at the same time or in succession.

If you use the traditional video on-demand method of monocular transmission, the time required to watch a video news is 1 minute; the time required to watch a movie program is 90 minutes. The client ordering a video news program needs to continuously occupy its 1M internet bandwidth within 1 minute of watching the video news, and the client ordering a movie program needs to continuously occupy its 1M internet bandwidth within 90 minutes of watching a movie. In order to support the on-demand of the client, the server also needs to occupy 1M Internet bandwidth, and each additional user occupies 1M more bandwidth. According to this calculation, this 100M bandwidth server The server can support up to 100 clients to request this movie program at the same time.

In the following example, the server also has 100M Internet bandwidth, and the client has 10M Internet bandwidth. The Internet between the server and the client supports multicast transmission. The server transmits data to each multicast transmission group with a bandwidth of 2M. The machine uses a multi-eye transmission group to receive data at the same time. It only takes 30 seconds to receive a 1-minute video program. In the following example, the delay in data transmission, the time in which directory information is transmitted, and the time in which clients and servers process data are ignored in calculating time.

Through the following examples, we will see what effect will be produced after the present invention is flexibly applied. For a group of data with a small amount of data, such as a video news, the server only needs to cyclically transmit the entire group of data with a ruler to one or more multicast transmission groups. If the server only transmits to a multicast group cyclically, the minimum waiting time from when the client selects this news to when it can be watched is greater than Q seconds, the longest is 30 seconds, and the average waiting time is 15 seconds . If the server cyclically transmits to five multicast transmission groups respectively, and the time when each multicast transmission cycle reaches the starting point of this piece of data is interlaced with each other, as shown in Figure 9A and Figure 9B, The minimum waiting time for the machine to select this news to be able to watch the news is greater than 0 seconds, the longest is 6 seconds, and the average waiting time is 3 seconds. This kind of waiting is still tolerable for people watching. The advantage of this method is that this server can support more than 100,000 clients to watch at the same time.

However, if the on-demand program is a movie program, simply using this method will not work. If the server cyclically transmits to 5 multicast transmission groups respectively, and the time when each multicast transmission loops to the starting point of this segment of data is If they are staggered with each other, the maximum waiting time from the client's selection of the movie program to the time when the movie program can be watched is 9 minutes, the shortest time is greater than Q seconds, and the average waiting time is 4 minutes 30 seconds. Such waiting is unbearable for people watching.

Therefore, for a group of data with a large amount of data, it is necessary to comprehensively use the method of looping, interleaving, dividing, and using the monocular transmission method in the present invention to reduce the waiting time of viewers.

1. The server processes a movie program (a set of data) in a data format into a format convenient for this mode and stores it in the server's memory:

a. The server divides the movie program to be sent into multiple fragments, for example, 10 The minute video is taken as the first clip, and every subsequent 20 minutes of video data is taken as a data clip. In this way, a movie will be divided into about 5 clips. This work can also be done in advance by other computers, even in the production of data Completed in the process;

b. Add a ruler to the data segment. This work can also be completed by other computers in advance; or it can be completed in the process of making data; or the ruler is not added when storing, but before the server sends the data to the network. Add ruler

c. Store each segment of the processed video data in the memory of the video server.

2. The server transmits each scaled data segment of the movie program to be transmitted to one or more multicast transmission groups. In this example, at least 5 multicast transmission groups are required to transmit this movie program, as shown in Figure 5 or The program A shown in FIG. 6 occupies the network bandwidth of the server 10M. Whether there is only one client or 100,000 clients, this program is requested. In this way, the client can flexibly choose to receive one or several data segments at the same time according to its needs, network bandwidth and processing capacity; greatly reducing the waiting time between the client from the on-demand program to the time the program can be watched, and the maximum waiting time is 5 Minutes, average wait time 2 minutes 30 seconds. In contrast, although traditional video-on-demand can be viewed at any time, it can only provide programs to 10 clients using 10M server network bandwidth, and can only provide 100 clients even if the entire 100M network bandwidth of the server is occupied. Section.

3. During the period that the server provides the movie program, the server transmits again after each video data segment is transmitted, so the cycle is repeated, so that the client that needs data can start receiving the data segment at any time and complete a complete cycle. As shown in FIG. 5 or FIG. 6, because the reception starting point when a client starts to receive a certain video data segment is not the starting point of the video data segment in most cases, but the reception starts from a certain point in the middle of the video data segment. So when the client receives the end of this video data segment, what it receives and stores is not a complete video data segment, but the second half of this video data segment. However, because the server transmits video data fragments in a circular manner, that is, the video data fragments are transmitted from the beginning again after the end of the video data fragments, so the client can continue to receive this after receiving the end of a video data fragment The first half of the video data segment is until reaching or exceeding that reception starting point, as shown in FIG. 4B or 4C.

4. If a client needs to request this movie program, it must first know the movie program Is divided into several video data fragments; which multicast group is used to transmit each video data fragment; if a video data fragment is transmitted using multiple multicast groups, the client also needs to know which multicast group to use Only the starting point of this video data clip can be downloaded first; or other related directory information. Therefore, the server is required to be able to transmit the directory information to the client in a single or multi-view transmission or other forms.

5. Because the server transmits the data segments that need to be transmitted in a cyclic manner using multi-mesh transmission, when the client needs to obtain some video data fragments, it can immediately join the corresponding multi-memory transmission group according to the directory information and use the data ruler. Record the starting point of the reception, until it is cycled to this starting point again or it can exceed the starting point of the reception, to further verify that the entire cyclic transmission of data has been received and assembled into a complete data segment, as shown in Figure 4B or Figure 4C.

6. According to the actual conditions such as the available network bandwidth, the processing capacity of the machine, and the actual requirements, the client can be automatically detected by software and hardware or manually defined to determine its simultaneous receiving mode:

E.g:

a. Only one video data segment is received at a time, and the entire program is gradually received, as shown in Figure 5.

b. Receive several video data segments at the same time, gradually receive the entire program, and also receive certain segments of another set of data, but require larger bandwidth and strong processing capabilities, as shown in Figure 6 programs A and B As shown.

c. Receive all video data segments at the same time, and also receive some segments of another set of data, but require larger bandwidth and strong processing capabilities, as shown in programs B and C of Figure 6.

In this way, clients with different network bandwidths can make full use of their bandwidth to receive programs as quickly as possible.

7. After receiving the video data, the client performs validation on the received data. If the data is found to be incorrect or missing, it can be corrected using one of the following methods or a combination of the following methods: a. Use the ruler of the data segment Positioning the wrong or missing video data in a monocular transmission mode requires the server to resend some of the video data with errors.

b. Use the ruler of the data segment to locate and record the error or missing video data. At a certain interval (such as time, data amount, number of segments), request the server to resend Incorrect part of the video data.

C. Use the ruler of the data segment to locate the erroneous or missing video data and calculate the time when a certain multi-purpose transmission group will cycle to this point next time, and record it. According to the positioning of the time or re-accept the part with errors in advance Video data, or accept the relevant parts as redundancy, as shown in the figure

As shown in 4D, the server may also be required to send part of the data with errors using a monocular transmission method.

8. After receiving the correct data, the client can remove the ruler and merge multiple video data segments to restore the original format of this group of video data. Or you can not remove the ruler and not merge the segments. Ignore when using these video data and combine the clips together, as long as the effect is the same as using the original set of data.

9. The basic functions of the present invention can be realized according to the above points, but there are still some shortcomings. Although the basic method described above can enable the client to greatly shorten the interval from when data is received to when it can be used, the client still needs to wait for a period of time to start using the data, because the client must wait at least until it sends The server of the first data segment can only receive the start of this set of data when it is sent to the beginning of the data segment in a loop. (The average waiting time depends on the size of the data segment. The smaller the data segment, the smaller the average waiting time. 1/2 of the time this piece of data takes. In this example, the client needs to wait up to 5 minutes, with an average waiting time of 2 minutes and 30 seconds (of course, during this time, the client can browse other online content or watch advertisements stored in the client in advance). Improve:

1) The server is allowed to transmit the first segment or the first several segments of a group of data in a monocular transmission mode while the data starting from the second segment is allowed to be transmitted in a multi-mode transmission mode, as shown in FIG. 7, because the client When downloading data in a single transmission mode, the data can be used from the beginning of the data in a timely manner, so when the client downloads the data that needs to be used immediately from the beginning, the server allows the client to start the download in a single transmission. One clip or several clips, while using the data of the first clip while downloading, and downloading the second clip or the last several clips at the same time. The time for the client to receive and use the data of the first segment transmitted by the monocular is sufficient to download the second segment of data to the client in a multi-mode transmission mode. While using this segment of data, it can continue Use this Way to download subsequent clips. In this way, the client can immediately watch the program after ordering it, but it increases the network load of the server. If the load of the directory information is not included, the server can support an average of 810 clients watching the program.

2) Allow the server to transmit the first fragment or the first few fragments of a group of data in a monocular transmission mode while allowing all data fragments to be downloaded in a multi-eye transmission mode, as shown in FIG. 8, because the client is When downloading data using the eye transfer method, the data can be used from the beginning of the data in a timely manner, so when downloading the data that needs to be used immediately from the beginning, it is allowed to send a fragment or several fragments of the download in a single eye. Use the data of the first clip while downloading, and download the first clip and the subsequent data clips in multiple transmissions. The client downloads and uses the first segment of data in a monocular transmission mode and also downloads and stores the first segment of data in a multicast transmission mode. In most cases, the server is sending data when the client starts receiving data. During a certain data segment, the starting point of the client's reception is not the starting point of this data segment. The client can use this receiving starting point as a boundary. When the client receives this receiving starting point by using the monocular transmission, the client can stop using the monocular. The data is received in the transmission mode, because the client has received part of the data after the start of the reception in the manner of multicast transmission and stored it in the memory, so that the client can immediately watch the program after ordering a program, but the resulting The network load is reduced by half compared to the previous method. If the load of the directory information is not included, the server can support an average of 1620 clients watching the program.

3) When the server transmits the first segment or the previous several segments to the outside, each segment uses several multiple transmissions and the time of its starting point is staggered with each other, so that the client can choose (this option can also be selected by the server Help the client) A multi-eye transmission group can download the movie program to the starting point of the loop more quickly, so that the client can start watching the movie program as soon as possible. As shown in FIG. 10, the server uses the first piece of video data of program A for three times. Multicast transmission group (a), (b), (c), transmission. If the client downloads data using the multicast transmission group (a), the data can be used from the U point of time; if the client uses multicast transmission If group (b) downloads data, the data can be used from time t1; if the client downloads data using multicast (c), then data can be used from time t3; if the client uses a suitable multi-mesh The transmission group can start using data from scratch as early as possible. FIG. 5 shows that a client uses a multicast group (b), and data can be used as early as possible at t1. If other customers If the client computer starts downloading at another time, you may choose another multicast group to start using the data as soon as possible. After this improvement, the client needs to wait at most 1 minute and 40 seconds, with an average waiting time of 50 seconds. This method allows more than 100,000 clients to order programs, but the server only increases the network load by 4M. If the first segment is transmitted using 20 multicast groups in this way, the client needs to wait up to 15 seconds, with an average waiting time of 7.5 seconds, and the server adds 3 network loads, that is, the total server load is about 48M .

4). You can also use the above points in a comprehensive way, so that the client can watch the program in real time without increasing the load on the server. As shown in Figure 12, the server transmits two sets of data A and B in multiple multicast transmission groups. Group A data is divided into 5 data segments. The first segment of Group A data is transmitted using three multicast transmission groups and the time to cycle to the starting point is interleaved with each other. Part of a fragment. The client receives the data using both monocular transmission and multicast transmission. When receiving data in a multicast transmission mode, the client starts to receive data according to the multicast transmission group to the starting point. It can be seen from the figure that because the multi-eye transmission group C is selected, the amount of data transmitted by a single eye can be minimized, and the server traffic for a large number of clients is greatly reduced.

5). When the first data segment is in the downloading process or the previous data segment has been used but the subsequent data segment download has not kept up, the client can be allowed to use other data that has been downloaded in advance, such as playing an advertisement Continue to use after downloading data during this period.

Considering geographical distance or national or administrative divisions, proxy servers can be set up in some places. The proxy server can obtain data from the server or other proxy server by the receiving method or other methods in this method, and can also send data to the client by the transmitting method in the present invention.

It should be understood that for a person of ordinary skill in the art, various possible changes or substitutions can be made according to the inventive concept and technical solution of the present invention, and all these changes or substitutions should belong to the appended claims of the present invention. Scope of protection.

Claims

Claim

1. A method for transmitting data in a cyclic manner using a multi-eye transmission in a data network, characterized in that the server transmitting the data takes the following steps:

a. The server stores at least a piece of data with a "ruler" in its memory to be transmitted; b. The server provides a catalog message about the data to be transmitted in a single-shot or multi-shot transmission mode.

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c. The server transmits the data to be transmitted to the corresponding multicast group through the network respectively. d. During the data transmission period, the server retransmits from the beginning again after the transmission of each multicast group is completed. At least one client only transmits data cyclically when receiving data, otherwise the loop is terminated, and data is not transmitted again until at least one client needs to receive data again.

2. The method according to claim 1, characterized in that the step a further comprises: a. The server stores a plurality of data segments with a "ruler" in a group of data to be transmitted in its memory, and respectively sends the data segments to at least A multicast transmission group.

3. The method according to claim 1, characterized in that: the server transmits at least one piece of data with a "ruler" to a plurality of multicast transmission groups, and each multicast transmission cycle to the starting point of the data in this segment The times are intertwined.

4. The method according to claim 1 or 2 or 3, characterized in that: when the server transmits a group of data fragments that are divided into a number of "scales", the server transmits the first data fragment or the first few data of the group of data Each data segment is transmitted to multiple multicast transmission groups, and the time when the multicast transmission group transmitting the same data segment is cycled to the start point of this segment of data is mutually staggered.

5. The method according to claim 1 or 2 or 3, characterized in that: during the multicast transmission of a certain piece of data, the server can respond to the request of the client by transmitting a part of this piece of data to the client in a monocular manner or All.

6. The method according to claim 1, wherein: the "scale" of the data uses the sequence number of the data packet as the scale scale.

7. The method according to claim 1, wherein: when a piece of data to be transmitted is When a number of small files are divided, the "scale" of the data uses the number of small files as a scale.

8. The method according to claim 1, wherein: the "scale" of the data uses the number of bytes or digits from a certain data point to the beginning or end of a data segment as a scale.

9. A method for receiving data in a data network by using a multiplex transmission loop, characterized in that the client receiving the data takes the following steps:

a. The client that needs to receive a piece of data fetches the directory information related to this set of data from the multicast transmission group or directly from the server;

b. According to the directory information, the client receives this piece of data from one or several multicast transmission groups that transmit this piece of data, and records the "reception point" at which it starts to receive; or requires the server to use the monocular transmission mode. Transfer data to it;

10. The method according to claim 9, characterized in that: when the received multiple pieces of data are each data piece after a set of data is divided into a plurality of data pieces, the client receives at least one piece of data at the same time and connects adjacent Data fragments, or to make them available as a whole.

11. The method according to claim 9, characterized in that: the client loops to the start time of the data segment according to the data transmitted cyclically, and uses the start point or the end point of the data segment as the

"Receiving origin", so that after receiving this piece of data, it is not necessary to connect it at the receiving origin.

12. The method according to claim 9, characterized in that: the client receiving the data verifies the data that has been received, and if the data is found to be wrong or missing, the wrong or missing data fragments are used by the The "ruler" is used to locate the scale, and calculates the time when a multi-eye transmission group will cycle to this scale next time according to the directory information, and joins the transmission group to receive data in time to correct or supplement some of the errors or missing data.

1. The method according to claim 9, characterized in that: the client receiving the data has After the received data is verified, if the data is found to be wrong or missing, the wrong or missing data segment is positioned with its "ruler", and then the server is requested to unilaterally send the part of the data with errors or missing.

14. A server system that realizes cyclic transmission of data using multi-eye transmission, including a memory, a central processing unit, and a network adapter. The server is used to send data, and is characterized by:

15. A client system that realizes cyclic transmission of data using multi-eye transmission, including a memory, a central processing unit, and a network adapter. The client system is used to receive data, and is characterized by: a. A client that needs to receive a certain piece of data To obtain directory information related to this group of data from the multicast group or directly from the server;

b. According to the directory information, the client receives this piece of data from one or several multicast transmission groups that transmit this piece of data, and records the "receiving start point" from which it starts to receive; or requires the server to send it to it in a single-shot manner. Transmit data

16. The client system according to claim 15, wherein, when the received multiple pieces of data are each data piece after a set of data is divided into a plurality of data pieces, the client system receives at least one piece of data at the same time, And connect adjacent pieces of data, or make it a whole Body to use.

17. The client system according to claim 15, wherein the client system loops to the start time of this piece of data according to the data transmitted cyclically, and uses the start point or connection of this piece of data.