I. Introduction
I believe that those who have learned the information collection module must come into contact with a concept when they search for real IP-related knowledge points in learning Web information collection: CDN acceleration. So what are CDNs? Why do enterprises use CDN? Just to hide your real IP? Obviously not. There is a concept in economics called opportunity cost. The use of CDN acceleration requires cost, so companies will definitely not use such high-priced and low-efficiency technologies in order to hide their real IP.
Of course, many partners have also heard of another concept: load balancing technology. Friends who have been exposed to both concepts will definitely be confused by them: Isn’t CDN and load balancing a technology? Don't they all solve the same problem? After all, they can all solve problems such as large user visits, high concurrency, tight server resources, and network delays. With such questions in mind, we discuss CDN acceleration and load balancing technologies through this article.
Two: CDN acceleration and load balancing technology
(1) CDN Acceleration Technology
CDN (Content Delivery Network) is called content distribution network in Chinese, and its essence is a technology that caches part of the content of the source site on a server near the end user. CDN technology is an intelligent virtual network built on the basis of the existing network. Relying on the edge servers deployed in various places, through the load balancing, content distribution, scheduling and other functional modules of the central platform, users can obtain the required content nearby and reduce network congestion. , Improve user access response speed and hit rate. The key technology of CDN mainly includes content storage and distribution technology. This conceptual explanation can be understood with real-life examples: Assume that a user places an order for a product with the JD app in Shenzhen, and the JD headquarters in Beijing receives the order information. If the product is sent from the Beijing main warehouse, it may take 3 days to reach the user, so the user experience will be poor. In order to solve this problem, JD.com has set up edge warehouses in Shenzhen or other regions. After the user places an order for the product, the server starts to use the algorithm to find out whether the edge warehouse closest to the user has the product ordered by the user, and if so, it will directly deliver the product from the edge warehouse closest to the user. 1 day. If the product is not available in the few edge warehouses closest to the user, the server will automatically transfer the goods from other warehouses or ship directly from the main warehouse in Beijing.
CDN technology is a technology that utilizes distributed nodes to cache and distribute static content on a global scale. CDN provides faster download speed and lower latency by storing static content (such as pictures, videos, script files, etc.) on servers closer to users. When a user visits a website, the content will be obtained from the closest CDN node instead of directly from the source server, thereby reducing the load on the source server and network pressure. To put it simply, some static files (css, html, pictures, media files, etc.) are stored on the major CDN node servers by copying, caching, etc. If the user is far away from the source server, and the requested content is transmitted from the source server to the user Delay may be caused by channel transmission distance, operators, bandwidth and other factors, resulting in poor user experience. The use of CDN technology can allow users to request content nearby, respond quickly, and improve user experience.
(2) Load balancing technology
Load Balance (Load Balance) is a technology for distributing network requests in a high-traffic or high-load environment. Its main purpose is to evenly distribute requests to multiple servers or computing resources to ensure that the load on each server is relatively balanced. Through load balancing, the throughput and response speed of the system can be improved, and individual servers can be prevented from crashing or being overloaded due to high load. Load balancing is a server cluster composed of multiple servers in a symmetrical manner. Each server has an equivalent status and can provide external services independently without the assistance of other servers.
Using real-life examples, it can be understood as follows: some time ago, Zibo barbecue was popular all over the country, and a large number of tourists poured into Zibo for a while. In order to solve the contradiction between the influx of people and the reception capacity, the local streets have implemented the method of dividing street functions [this is the author's nonsense, Zibo did not have such a policy at the time, and the author here is only to explain the technical principles]. That is, the 1st street is all the mutton barbecue area, the 2nd street is the beef barbecue area, the 3rd street is the XX barbecue area, and so on. When tourists get off the expressway intersection, according to the needs of tourists, the street function allocation system guides tourists to 1st street, 2nd street or other streets. This solves the problem of tourists getting together on a certain street and causing street congestion.
Load balancing technology is to use some kind of load sharing technology (load balancing algorithm: polling, weighted polling, minimum number of connections, etc.), to evenly distribute the requests sent from the outside to a certain server in the symmetrical structure, and receive The requesting server independently responds to the client's request. The essence of load balancing technology is to balance and distribute the load (working tasks) to multiple operating units for operation.
Three: Summary
Load balancing technology mainly focuses on distributing requests to multiple backend servers in a geographical area to improve performance and reliability. The CDN acceleration technology mainly focuses on caching and distributing static content to nodes closer to users on a global scale, so as to provide faster download speed and reduce the load on the source server.
In practical applications, load balancing technology and CDN acceleration technology can be used in combination to achieve complementary advantages, and cooperate to solve the problem of server access load to further optimize network performance and enhance user experience.