Three technologies of CDN application
The realization of CDN needs to rely on a variety of network technologies, such as load balancing technology, dynamic content distribution and replication technology, caching technology, etc. The following is a brief introduction for you:
1. Load balancing technology
Load balancing technology is to distribute the traffic in the network as evenly as possible to multiple servers or network nodes that can complete the same task, so as to avoid overloading and paralysis of a single or part of the network nodes, affecting normal network access.
2. Dynamic content distribution and replication technology
In most cases, there is a close relationship between website response speed and the distance between the visitor and the website server. If the distance between the visitor and the website is too far, the information transmission between them will have to go through multiple routes, forwarding and processing, and the network delay will be greatly increased. The content distribution and replication technology is to distribute and copy most of the static pages, images, and streaming media data in the main body of the website to the acceleration nodes in various places. Therefore, dynamic content distribution and replication technology is also an important technology required by CDN.
3. Cache technology
Caching technology is not a new technology. Web caching services improve user response time in several ways, such as proxy caching services, transparent proxy caching services, transparent proxy caching services using redirection services, and so on. Through the Web cache service, users can minimize the traffic of the WAN when accessing web pages. For corporate intranet users, this means caching content locally without retrieving pages across a dedicated WAN. For Internet users, this means storing content in their ISP's cache without retrieving web pages over the Internet. This will undoubtedly increase the user's access speed.
CDN service mode
Content distribution network (CDN) is a strategically deployed overall system, including distributed storage, load balancing, network request redirection, and content management. Content management and global network traffic management (Traffic Management) are The core of CDN.
By judging by user proximity and server load, CDN ensures that content is served to user requests in an extremely efficient manner. In general, the content service is based on the cache server, also known as the proxy cache (Surrogate), which is located at the edge of the network, only "one hop" (Single Hop) away from the user.
At the same time, the proxy cache is a transparent mirror of the source server of the content provider (usually located in the data center of the CDN service provider). Such an architecture enables CDN service providers to provide the best possible experience on behalf of their customers, content providers, to end users who cannot tolerate any delay in request response time.
Five advantages of CDN
1. Local Cache acceleration, which improves the access speed of enterprise sites (especially sites with a lot of pictures and static pages);
2. Network acceleration across operators to ensure that users of different networks get good access quality;
3. Remote access users intelligently and automatically select Cache servers according to DNS load balancing technology
4. Automatically generate the remote Mirror (mirror) cache server of the server, read data from the cache server when remote users access, reduce the bandwidth of remote access, share network traffic, reduce the load of the web server of the original site, etc.;
5. Widely distributed CDN nodes and intelligent redundancy mechanism between nodes can effectively prevent hacking.