Explanation of the principles and processes of video CDN technology

Video CDN is a set of self-developed distributed platform tailored for mobile Internet video content distribution. The platform is centered in Shenzhen, and servers distributed in BGP computer rooms across the country are edge nodes, bringing together China Telecom, China Unicom, and China Mobile. , China Education Network and other operators' network resources, build a nationwide network coverage network, cache or mirror video content to these node edge servers, and provide video content acceleration services for different users in different regions. Realize nearby access, thereby speeding up the access speed, improving the user's access experience, and avoiding the problems of excessive server load and insufficient bandwidth resources caused by the excessive traffic of the source site, solving network congestion, and improving the response speed of users accessing the website. Effectively guarantee user experience.

The http request processing flow after using CDN is as follows:

Node cache: combine multiple JavaScript/CSS files into one request, thereby reducing the number of requests (Lua)

Taking the video CDN product of Yunzhou Multimedia Technology Co., Ltd. as an example, its technical architecture and workflow are explained as follows:

Based on the regional characteristics of media content and real-time streaming media programs, unlike ordinary CDNs, Yunzhou Video CDN adopts a distributed multi-source architecture, which allows edge nodes located in different geographic locations to publish their own media content and real-time programs independently. That is, each edge node can also be used as a source station to some extent, and can also distribute these contents and programs to sub-nodes located in other places, so each node can exist as a system center source station, and at the same time, it can realize edge The function of the node. The source site can also be used as an edge node to receive fast response services for user video content. For ordinary Internet users, each CDN edge node is equivalent to a Web site placed around it, controlled by the load balancing system , the user's request is transparently directed to the node closest to the user and with the best network status. The WebServer server in the node will respond to the user's request quickly just like the original server of the website.

Website/Application Acceleration:

Users can pre-define the rules of content distribution, add permissions and priorities to the uploaded content, after the content is uploaded, they can choose to deploy the hot content with high priority to other nodes in advance, and those with low priority can not be synchronized first , only stored in the local source station, the system establishes a global content retrieval query index, once a user accesses, the system intelligently judges the application layer access request, according to the actual geographical location of the real user, the operator, and the distribution Information such as node health status, network traffic, load status, and distance to users in the entire network, according to various optimization strategies, through dynamic content distribution of the network and global load balancing, redirect user requests to the closest and healthy and available On the node cache server, users can obtain the required content nearby. If the required content does not exist in this node, the system will automatically start the content retrieval function, and return to the source to obtain the required content source in real time and provide it to the user.

Utilizing Yunzhou Multimedia's video CDN network, network content providers do not need to invest in various expensive servers or set up sub-sites. Its basic video service has massive storage and distribution capabilities, which can help video websites save traffic. Especially for video streaming information, distance learning courseware and other network application services that consume a lot of bandwidth resources, CDN technology is used to copy the content to the edge of the network, so that the distance between the content request point and the delivery point is minimized. The improvement of Web site performance is of great significance. After the website uses CDN, the CDN service provider is responsible for the transmission of information to ensure the transmission of information, while the website only needs content maintenance, and no longer needs to consider bandwidth server issues. CDN can provide guarantees for the speed, security, stability, and scalability of the network.

Acceleration of video and audio on demand/large file download and distribution:

At present, the cloud video CDN network system can provide services such as video content on-demand acceleration, live broadcast acceleration, website content cache acceleration, and mirror deployment. Wanshi Wuyou video hosting platform of Yunzhou Company relies on the powerful video CDN product independently developed by the company, breaks the technical model of acceleration solutions provided by traditional CDN equipment manufacturers, and creates a CDN technology that meets the conditions of China's Internet/mobile Internet , can eliminate the huge basic investment and R & D and operation and maintenance investment of video content customers, and at the same time make the effect of video content distribution reach professional fluency and expressiveness in heterogeneous networks. It effectively reduces operating costs and adapts to the complex network environment of China's national conditions. Provide high-performance Internet and mobile Internet video cloud services according to customer needs, so that customers can enjoy broadcast-level audio-visual content with only the lowest cost investment.

Yunzhou Video CDN is mainly composed of five parts: global intelligent analysis system, load balancing scheduling system, content routing synchronization system, distributed storage management system, background management system, etc.

The technical architecture of Yunzhou Video CDN is shown in the figure below:

The service process of Yunzhou Video CDN:

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When an end user accesses streaming video content, the load balancing system first determines the best edge node closest to the user, and at the same time directs the end user's request to this node. When the end user's request reaches the designated node, the edge node server is responsible for providing the requested content to the end user.

The basic service flow for end-user access is as follows:

1. End users access the video content specified by the website through the domain name, and the user request will be finally processed by the local DNS to the cloud video CDN load balancing system;

2. The load balancing system intelligently judges the geographical area and operator of the visiting user, and collects the load and health status of the relevant nodes, and returns the optimal and nearest network edge node IP to the user;

3. The end user sends a media request to the corresponding network edge node to request content according to the returned IP address;

4. Network edge nodes receive customer requests, and select appropriate server equipment to provide services to customers according to the actual capabilities and load conditions of each device in the node;

5. If the content requested by the user exists in the local edge node, the media content requested by the user is directly sent to the end user.

6. If the content requested by the user does not exist in the local edge node, search the corresponding program list database to find the best node with the target content;

7. The edge node redirects the user request to the node that stores the target content, and the node completes the response service to the user request;

8. The local edge node starts the function of pulling the target content, and synchronizes the target content from the redirection node for subsequent users to visit nearby;